Aleph J illustrated build guide
An illustrated guide to building the Aleph J
This is a guide to building the Nelson Pass / Firstwatt 'Aleph J' amplifier.
A few links to start off -
Aleph J Manual (From firstwatt.com) http://firstwatt.com/pdf/prod_aj_man.pdf
Amplifier PCB (From DIYaudio) Aleph J (2 PCBs included, which makes 2 channels) - Circuit Boards
Discussion thread - Aleph J for Universal Mounting Spec - diyAudio
Bill of Materials (BOM) - diyAudio
Schematic -
Ok!
The bulk of this guide is going to show the green PCB, which were proof-of-concept prototypes. The boards worked great and we needed to make very minor changes to the production boards, which are blue. There is effectively no difference between the prototype and production boards. Also worth note, the photos of the PCB will be from two different builds, mine (6L6), and Grimberg's. There are no significant differences in how the PCB was stuffed or utilized. I think Grimberg did a prettier job stuffing the PCB than I did. 🙂
Also, this build will show a 5U 'Big Amp Chassis' from the DIYaudio store. (Because that's what I have on hand.) The Aleph J can be made into the 4U 'Jack of all Chassis', everything will fit and the heatsinks are (just) big enough. All the specifics surrounding the 'premium' chassis (back panel, perforated base, pre-drilled heatsink, etc…) are functionally identical, the differences between the 4U and 5U are mainly just size. Regardless of the chassis you use, this amp does get quite hot, and good ventilation will be required around the entire chassis.
On to the guide.
Here is the PCB. It's a great layout, please thank member Didiet78 for his work making this. 😀
Front
Back
Stuffing the PCB
The normal order of operations is to do the little things first and place the bigger things as you proceed.
This PCB has 4 connections that are normally going to be jumpers. (R6, R30, J1, J2) You can see them here. These connections can be jumpered with little bits of wire or cut-off resistor leads, your choice.
These 4 pads are there in case you need to add some resistors in case of oscillation, which may happen to some builds. It's rare, but if you need it, there is place on the PCB to add some compensating devices.
R27. SEE TEXT
Let's talk about this - as it is somewhat confusing.
There are 3 places for R27 on this PCB. The first is the pad next to the cap C2. (in the above photo it is empty) I suggest making that one a jumper.
Where the jumper is placed in the photo should be open, and under the green insulation you will find the place for a pot.
SO - place a 100K pot where the pot will fit and jumper the vertical 'R27'. Set the pot to 68K before you turn the amp on the first time.
Here you can see how the pads for the pot are arranged - (underneath where it says "LTP Bias" and similarly under "offset")
The small oval pads are where the pot connects. The larger round pads outboard of the silkscreen are for a resistor if you choose to put it there in lieu of the pot, or can be used to measure across the pot in circuit. Cool, huh?
Also, it does not matter which of the center pads you use - some pots have all three pins in a row, some have the center pin offset. Either type will be fine.
Add the resistors. Shown here are big-bodied Dale RN60. If these fit, and they do, most other resistors will as well. Use whatever parts suit your fancy.
Now add the bigger (3Watt) resistors. It's a good idea to leave some room between the PCB and the body to let air circulate. As shown here -
The best advice I can give you is this - measure every resistor before inserting into the board.
Continue on with caps and the small transistors
Eventually the board will look something like this -
For reference, know that the Power Mosfets (obviously not mounted yet…) on the Left side of the PCB, near the electrolytic capacitors are for the Constant Current Source, and the Mosfets on the Right side, closer to the red input film capacitor, are the Outputs.
Note that in this photo, the vertical R27 is jumpered, and there is a 68K resistor in the horizontal spot. I later replaced the resistor with a pot.
Here is the pot in that position. I used a single-turn because I had one on hand... I strongly suggest multi-turn pots on all of these projects.
Yes, have my LED colors reversed. The V+ should be red. I've even had it marked backwards in the schematic. Lol. 🙂 You could make them all blue, this is a Pass amp, after all… 🙂
The LED on the PCB are there to show that you have the rails connected and the amp PCB is getting voltage. If you want to extend the leads on one of these and make it a panel light, feel free.
Power Supply
The power supply for the Aleph J is going to follow the basic pattern of the Pass/Firstwatt DIY amplifiers. Please look at the following schematic --
The basic topology is this. 18+18V transformer, of at least 300VA, CRC filter with 8 15,000uF 25V capacitors and 8 (4 per rail) 0.47ohm 3W resistors.
May you use a transformer with more VA? Yes, of course.
May you use larger Capacitors? (more uF) Yes.
May you use capacitors with a different voltage rating? Yes, as long as you have 25V or more. (25V, 50V, etc…)
Remember that the factory Firstwatt amps use 300VA transformers and (8) 15,000uF 25V caps. If that's good enough for Papa… It should be good enough for you. But almost everybody makes it bigger. No problem at all. It's easy, so you might as well... 🙂
In this build I am using the old (smaller) DIYaudio PSU board. This particular one has no blue soldermask on the top of the PCB. It is otherwise identical. The section for the discrete diode bridges has been snapped off.
IMG_0822 - My Photo Gallery
Here shown with the Filter resistors (0.47Ohm, 3W, light blue), the Bleeder (2.2Kohm, 3W, dark blue) and LEDs.
For some reason I can get the LED color correct on this PCB… Red for V+, Green for V-
The PCB can accept (8) caps with 10mm lead spacing and 30mm diameter, or (4) of 35mm diameter. These are 33,000uF 35V Panasonic T-UP series caps.
I prefer to use diode bridges in these monolithic blocks.
Bridge connections.
IEC inlet.
120V AC wiring shown - this is the primaries of the transformer. AC will attach to the center terminals.
You are free to comment or question. 😀
This is a guide to building the Nelson Pass / Firstwatt 'Aleph J' amplifier.
A few links to start off -
Aleph J Manual (From firstwatt.com) http://firstwatt.com/pdf/prod_aj_man.pdf
Amplifier PCB (From DIYaudio) Aleph J (2 PCBs included, which makes 2 channels) - Circuit Boards
Discussion thread - Aleph J for Universal Mounting Spec - diyAudio
Bill of Materials (BOM) - diyAudio
Schematic -
Ok!
The bulk of this guide is going to show the green PCB, which were proof-of-concept prototypes. The boards worked great and we needed to make very minor changes to the production boards, which are blue. There is effectively no difference between the prototype and production boards. Also worth note, the photos of the PCB will be from two different builds, mine (6L6), and Grimberg's. There are no significant differences in how the PCB was stuffed or utilized. I think Grimberg did a prettier job stuffing the PCB than I did. 🙂
Also, this build will show a 5U 'Big Amp Chassis' from the DIYaudio store. (Because that's what I have on hand.) The Aleph J can be made into the 4U 'Jack of all Chassis', everything will fit and the heatsinks are (just) big enough. All the specifics surrounding the 'premium' chassis (back panel, perforated base, pre-drilled heatsink, etc…) are functionally identical, the differences between the 4U and 5U are mainly just size. Regardless of the chassis you use, this amp does get quite hot, and good ventilation will be required around the entire chassis.
On to the guide.
Here is the PCB. It's a great layout, please thank member Didiet78 for his work making this. 😀
Front
Back
Stuffing the PCB
The normal order of operations is to do the little things first and place the bigger things as you proceed.
This PCB has 4 connections that are normally going to be jumpers. (R6, R30, J1, J2) You can see them here. These connections can be jumpered with little bits of wire or cut-off resistor leads, your choice.
These 4 pads are there in case you need to add some resistors in case of oscillation, which may happen to some builds. It's rare, but if you need it, there is place on the PCB to add some compensating devices.
R27. SEE TEXT
Let's talk about this - as it is somewhat confusing.
There are 3 places for R27 on this PCB. The first is the pad next to the cap C2. (in the above photo it is empty) I suggest making that one a jumper.
Where the jumper is placed in the photo should be open, and under the green insulation you will find the place for a pot.
SO - place a 100K pot where the pot will fit and jumper the vertical 'R27'. Set the pot to 68K before you turn the amp on the first time.
Here you can see how the pads for the pot are arranged - (underneath where it says "LTP Bias" and similarly under "offset")
The small oval pads are where the pot connects. The larger round pads outboard of the silkscreen are for a resistor if you choose to put it there in lieu of the pot, or can be used to measure across the pot in circuit. Cool, huh?
Also, it does not matter which of the center pads you use - some pots have all three pins in a row, some have the center pin offset. Either type will be fine.
Add the resistors. Shown here are big-bodied Dale RN60. If these fit, and they do, most other resistors will as well. Use whatever parts suit your fancy.
Now add the bigger (3Watt) resistors. It's a good idea to leave some room between the PCB and the body to let air circulate. As shown here -
The best advice I can give you is this - measure every resistor before inserting into the board.
Continue on with caps and the small transistors
Eventually the board will look something like this -
For reference, know that the Power Mosfets (obviously not mounted yet…) on the Left side of the PCB, near the electrolytic capacitors are for the Constant Current Source, and the Mosfets on the Right side, closer to the red input film capacitor, are the Outputs.
Note that in this photo, the vertical R27 is jumpered, and there is a 68K resistor in the horizontal spot. I later replaced the resistor with a pot.
Here is the pot in that position. I used a single-turn because I had one on hand... I strongly suggest multi-turn pots on all of these projects.
Yes, have my LED colors reversed. The V+ should be red. I've even had it marked backwards in the schematic. Lol. 🙂 You could make them all blue, this is a Pass amp, after all… 🙂
The LED on the PCB are there to show that you have the rails connected and the amp PCB is getting voltage. If you want to extend the leads on one of these and make it a panel light, feel free.
Power Supply
The power supply for the Aleph J is going to follow the basic pattern of the Pass/Firstwatt DIY amplifiers. Please look at the following schematic --
The basic topology is this. 18+18V transformer, of at least 300VA, CRC filter with 8 15,000uF 25V capacitors and 8 (4 per rail) 0.47ohm 3W resistors.
May you use a transformer with more VA? Yes, of course.
May you use larger Capacitors? (more uF) Yes.
May you use capacitors with a different voltage rating? Yes, as long as you have 25V or more. (25V, 50V, etc…)
Remember that the factory Firstwatt amps use 300VA transformers and (8) 15,000uF 25V caps. If that's good enough for Papa… It should be good enough for you. But almost everybody makes it bigger. No problem at all. It's easy, so you might as well... 🙂
In this build I am using the old (smaller) DIYaudio PSU board. This particular one has no blue soldermask on the top of the PCB. It is otherwise identical. The section for the discrete diode bridges has been snapped off.
IMG_0822 - My Photo Gallery
Here shown with the Filter resistors (0.47Ohm, 3W, light blue), the Bleeder (2.2Kohm, 3W, dark blue) and LEDs.
For some reason I can get the LED color correct on this PCB… Red for V+, Green for V-
The PCB can accept (8) caps with 10mm lead spacing and 30mm diameter, or (4) of 35mm diameter. These are 33,000uF 35V Panasonic T-UP series caps.
I prefer to use diode bridges in these monolithic blocks.
Bridge connections.
IEC inlet.
120V AC wiring shown - this is the primaries of the transformer. AC will attach to the center terminals.
You are free to comment or question. 😀
Another EMI filter
- Power Supplies
- 143 Replies
The most important thing in an EMI filter are the coils, these must have a particularly high permeability and a very low internal resistance, smaller coil values and very large X2 capacitors are best in order to achieve a lower cutoff frequency of the filter, be careful with Y capacitors, too high values can trigger the FI!
The last picture shows a Chinese DC filter and EMI filter board, which sits directly in front of the transformer in a ChipAmp amplifier.
The last picture shows a Chinese DC filter and EMI filter board, which sits directly in front of the transformer in a ChipAmp amplifier.
Determining heatsink size for P3A
- By delverboy
- Solid State
- 9 Replies
Rod's instructions say "a 0.5°C/W heatsink for normal hi-fi use if the quiescent current is maintained at the minimum recommended of 20mA."
I don't know what to do with that.
This is the heatsink I was considering and I found this calculator, but I'm not sure what value to use for Ts (max).
I don't know what to do with that.
This is the heatsink I was considering and I found this calculator, but I'm not sure what value to use for Ts (max).
DAC design based on PCM5102A
- By kiks64
- Electronic Design
- 68 Replies
Hi there !
After an attempt to design a bluetooth DAC, with questionable technical choices, I decided to be reasonable and make an S/PDIF version.
The DAC is still based on the PCM5102A chip, without additional preamplification stage, and the 100x50mm 4-layer PCB receives one ground plane per layer, connected together by vias.
I will use this module for S/PDIF to I2S conversion: https://www.audiophonics.fr/en/inte...spdif-to-i2s-dir9001-24bit-96khz-p-17274.html
For volume control, I'll use this: https://www.audiophonics.fr/en/preamplifier-modules/motorized-volume-control-board-50k-p-15006.html
From what I understand, the DIR9001 module will synchronize to the S/PDIF clock, and the PCM5102A will also synchronize via the I2S bus. I still connected the MCK pin of the DIR9001 module to an oscillator, so the DAC should keep running correctly without an S/PDIF signal, because my Tripath amp does not like to operate without a source.
I placed an LC filter at the 12V input because the DAC will be powered by an external SMPS power supply. Please tell me if the values of this filter are correct.
As advised for my previous design, the low noise 3.3V LDO is cascaded to a much larger 5V LDO to lighten its workload.
As this design was quite conventional, I couldn't resist adding a quirk, a high pass RC filter, for optional use.
Indeed, I chose the PCM5102A because it is the only decent DAC chip that I felt capable of implementing, being a beginner. But I know that it tends to be a little too generous in low frequencies.
So I added this high pass RC filter which cuts at 48Hz in the hope of being able to obtain more controlled and clean bass, if the need arises. I can use capacitors with significantly different values to fine-tune the filter. Let me know if this is a bad idea 🙂
EDIT : I just saw a big error on my high pass filter which in reality is a low pass 🤣. I am going to correct this and I am thinking of using a relay in order to be able to bypass this filter easily.
And here are the pictures :
After an attempt to design a bluetooth DAC, with questionable technical choices, I decided to be reasonable and make an S/PDIF version.
The DAC is still based on the PCM5102A chip, without additional preamplification stage, and the 100x50mm 4-layer PCB receives one ground plane per layer, connected together by vias.
I will use this module for S/PDIF to I2S conversion: https://www.audiophonics.fr/en/inte...spdif-to-i2s-dir9001-24bit-96khz-p-17274.html
For volume control, I'll use this: https://www.audiophonics.fr/en/preamplifier-modules/motorized-volume-control-board-50k-p-15006.html
From what I understand, the DIR9001 module will synchronize to the S/PDIF clock, and the PCM5102A will also synchronize via the I2S bus. I still connected the MCK pin of the DIR9001 module to an oscillator, so the DAC should keep running correctly without an S/PDIF signal, because my Tripath amp does not like to operate without a source.
I placed an LC filter at the 12V input because the DAC will be powered by an external SMPS power supply. Please tell me if the values of this filter are correct.
As advised for my previous design, the low noise 3.3V LDO is cascaded to a much larger 5V LDO to lighten its workload.
As this design was quite conventional, I couldn't resist adding a quirk, a high pass RC filter, for optional use.
Indeed, I chose the PCM5102A because it is the only decent DAC chip that I felt capable of implementing, being a beginner. But I know that it tends to be a little too generous in low frequencies.
So I added this high pass RC filter which cuts at 48Hz in the hope of being able to obtain more controlled and clean bass, if the need arises. I can use capacitors with significantly different values to fine-tune the filter. Let me know if this is a bad idea 🙂
EDIT : I just saw a big error on my high pass filter which in reality is a low pass 🤣. I am going to correct this and I am thinking of using a relay in order to be able to bypass this filter easily.
And here are the pictures :
New topology for current limiter
- By stigigemla
- Solid State
- 3 Replies
Looking in another thread whith an unusual current limiter an idea struck me.
Here is a simple current limiter working on the base current of the output transistors.
Of course there is some potential problems. We must have output transistors with a known current gain jus as well as the drivers and the limiters.
And when the base current is limited the fast switching will also be limited. But it is simple and nearly fits a SOA with max current at low voltage for the output tranistor and 0 current with max voltage. If the current gain is 100 for all transistors max current is about 15 ohm from full voltage. Max current 5,3 A in this case and the half with the output short to ground.
The IS 1 and 2 is just for DC simulation.
Here is a simple current limiter working on the base current of the output transistors.
Of course there is some potential problems. We must have output transistors with a known current gain jus as well as the drivers and the limiters.
And when the base current is limited the fast switching will also be limited. But it is simple and nearly fits a SOA with max current at low voltage for the output tranistor and 0 current with max voltage. If the current gain is 100 for all transistors max current is about 15 ohm from full voltage. Max current 5,3 A in this case and the half with the output short to ground.
The IS 1 and 2 is just for DC simulation.
Crossover schematic potentiometer/rheostat question
- Multi-Way
- 4 Replies
I'm planning to build the above crossover and have a 25ohm rheostat I'm hoping that there is some way to use for P1.
Is it possible to sand a portion of the metal rheostat body and solder the 15ohm resistor to it as a 3rd lug, or do I just
need to purchase a wire wound 25ohm potentiometer with 3 lugs? Rheostat in question is pictured below.
Thank for your help.
2-Way MEH build
After months of research on Multiple Entry Horns, I’ve decided to build my own. While there are some excellent designs available, I’ve decided to design my own due to size constraints and budget limitations. My goal is to build a complete system for under €2000, including drivers, amplifiers, DSP, materials etc.
I’ll be documenting the journey and sharing the lessons I learn along the way. Since I’m new to this, I’d greatly appreciate any feedback or suggestions for improvement.
For those unfamiliar with Multiple Entry Horns (also known as Synergy or Unity Horns), I’ll include some resources below. In this post, I’ll refer to them as MEHs.
Why Synergy horns?
Synergy Calc V5
Synergy Patent
SynTripP: 2-way 2-part Virtual Single Point Source Horn | diyAudio
Scott Hinson’s MEH
The Design
Designing this project involved plenty of trial and error with drivers, designs, and Hornresp parameters. First I was going to build a 3-way MEH using four 4” drivers and two 10” drivers per horn + big subs using 15” drivers. However, when I discussed this with my better half, she wasn’t happy with the big size. So I changed it to a more compact design: 30x30cm 2-way MEHs paired with subwoofers.
For the 3-way MEH I got ideas and insights from Syn 9/Syn 10 and Cosynes, Scott Hinson’s MEH and SynTripPs. After deciding to go with a smaller horn, I began exploring more compact designs, such as: Two way synergy Horn, Portable Battery Powered MEH Build and others.
Size
Using Synergy Calc , I calculated the size and parameters for Hornresp. According to Bill Waslo: “with horns, bigger is better!”. While I would have preferred larger dimensions, I had to consider WAF, so I settled on a 30x30cm horn with an 80° coverage angle and horizontal pattern control to 850 Hz. After reading this discussion I changed the S1 value to 5.06 to match the CDs opening area to get a more precise Hornresp Simulation..
Drivers
Hornresp is a fantastic tool for modeling speakers, big thanks to David McBean for his contributions! After countless evenings testing various drivers and parameters, I settled on the following components:
Compression Driver - FaitalPRO HF108 (8Ω) I chose it because it works well in short horns and wide dispersion waveguides and people seem to like it a lot. The recommended crossover is 1300 Hz, which is what I’ll go with in my design.
Midrange - 2x FaitalPRO 4FE35 (8Ω) in parallel - they simulated well in Hornresp and have been used in some MEH builds before.
Hornresp parameters
3d printed horn
The inner section of the horn (shown in light grey in the 3D rendering) will be 3D-printed, while the outer flare will be constructed from 2 sheets of 19mm MDF with a dispersion angle of 130 degrees
The HF108 compression driver has a 31-degree exit angle, so the horn starts with a matching 31-degree angle and gradually transitions to an 80-degree angle at the midrange entry point.
To minimize unexpected cancellation notches, the inner corners of the horn are smoothed with 2mm rounded edges.
Mid driver Port location:
From Why Synergy horns?:
I’m crossing between the mid and the compression driver (CD) at 1300 Hz, which means the port holes for the mid drivers should be within 6.596 cm (calculated as 343/1300/4) of the CD’s exit.
I’ve been wondering if the critical distance is measured from the mid ports to the CD’s acoustic diaphragm or its exit. The CD’s exit seems to work well in previous designs posted here, so I decided to go with that. This approach also simplifies placement by allowing the ports to be positioned farther out.
To ensure I stayed within the critical distance, I decided to shorten L12 slightly (the distance between the CD’s exit and the plane of the mid-entry ports). L12 is 4.28 cm, meaning the centre of the mid-entry port is 5.84 cm from the centre of the CD’s exit, so it’s well within the required 6.596 cm for the crossover.
The circumference of the cross-sectional area at the tap-in point is calculated as 6.531*4=26.124, which is close to the wavelength of 1300 Hz.
However, when I model it in Hornresp, the cancellation notch appears well above 1300 Hz, and the mids start to roll off around 2000 Hz. I can increase the distances well above 6.6 cm before I get the cancelation notch near 1300 Hz. I’m not sure if I’ve missed something in my calculations and the measurements may differ when I measure the build speakers.
Mid driver Vrc:
I made the Vrc (closed rear chamber volume) fairly small 2 L in total (1L per driver). I still haven’t figured out how I will limit the chamber volume. Using tubes like those in the Cosynes would be challenging due to the distance between the mids and the compression driver.
Mid driver Vtc:
I didn’t feel like I needed to minimize the Vtc (throat chamber volume) as the mids can play high enough frequency already. Making it smaller using cone plugs seems more beneficial with bigger woofers (like on the SynTripPs) and also the B&C 4NDF34 which have been used in some designs. For now I’ve estimated 50cc per driver, but will measure the volume when I receive them. I might adjust the sizing after doing the final calculations with the correct volume.
Mid driver port size:
There are 2 entry ports per driver, 4 in total. The entry points are frustrumised, 2.76 cm in diameter closest to the driver and 1.95 on the inside of the horn, which translate to Ap1 of 24 cm² and Ap2 of 12 cm².
The ports are relatively small, with port velocity exceeding 17 m/s when played above 105 dB below 200 Hz. These are meant for home hi-fi use, so I don’t plan to play them too loud. I also don’t want to make them too big, so they affect the CD’s output. The ports are placed next to the corners to minimise the effect they have on the CD.
Vertical drivers:
This is something I haven’t seen mentioned often, and it seems to be overlooked in many MEH designs. I will place all the drivers vertically, on the side walls of the horn, to avoid driver sag.
Ported or sealed box:
While I was designing the 3-way MEH with 2x 10” woofers I tried modeling the low drivers in both ported and sealed box. I ended up choosing sealed after reading Arts comment from the SynTripP thread.
Subwoofers:
I haven’t decided on the subwoofers yet.
I’m considering adding two subs within the same enclosure as side-firing woofers in a push-push alignment. For example, two GRS 8SW-4HE drivers in a sealed configuration with a ca 42L volume. Here is a promising recommendation for these woofers.
If I go with this approach, I might decrease the vertical coverage angle of the MEH horn to 60 degrees to make space for the woofers below the horn. I guess it would be good idea to have the woofers close to the horn, within ¼ wavelength of the crossover frequency, but have also read that it doesn’t matter very much for frequencies below 100 Hz.
Adding the subs in the same enclosure would significantly increase the height of the enclosure, which may not pass the WAF. Alternatively, I could build a separate subwoofer placed approximately 1.5 meters away
Is it better to integrate side-firing subwoofers within the same enclosure or should I make a separate enclosure, which would need to be ca 1.5m away? I’d appreciate any feedback or suggestions on driver selection!
Amplifier and DSP:
As I don’t own any of the parts needed I have the opportunity to build the whole system from scratch.
The TPA3255/51 amps seem to offer great value for the money.
I’m looking into: Fosi ZA3, AIYIMA A70, Topping PA5 II and the upcoming 3e audio amps. I haven’t decided yet and would appreciate any recommendations.
Finding a DSP solution that fits the budget has been tricky. High-quality DSPs can be expensive, while the cheaper options often come with limitations.
I’ve decided to go with a Raspberry Pi 5 running CamillaDSP. For the DAC, I’ll start with the cheapest option: the AliExpress cards mentioned in this guide. RPi 5 Quad Stereo Sound with PCM5102A – Simple DIY Electronic Music Projects. User dptucunduva has had good results with it.
The reasons I chose it are:
It’s cheap and has good potential for upgrades. I can switch out the DAC module for a proper sound card like the Motu Ultralite mk5.
It’s a very flexible system, the Raspberry Pi can act as a streamer and allows for lots of add-ons like a remote controller, Those who use CamillaDSP seem very happy with it.
HiFiBerry DAC, which uses the same DAC chip seems to be decent according to the measurements here. I’m not expecting any fantastic results but see it as a cheap solution that has all the active crossover functions needed.
Next steps:
The CD and mid-drivers are on their way, and I plan to begin 3D printing the horn in early January. In the meantime I’ll focus on refining the horn design, adding mounting holes, figure out how to do the right vrc size. I also need to decide which amplifiers to use and start building the Raspberry Pi DSP. Additionally, I’ll work on designing the subwoofers and determining whether side-firing woofers are the best option.
Any suggestions or input would be greatly appreciated!
I’ll be documenting the journey and sharing the lessons I learn along the way. Since I’m new to this, I’d greatly appreciate any feedback or suggestions for improvement.
For those unfamiliar with Multiple Entry Horns (also known as Synergy or Unity Horns), I’ll include some resources below. In this post, I’ll refer to them as MEHs.
Why Synergy horns?
Synergy Calc V5
Synergy Patent
SynTripP: 2-way 2-part Virtual Single Point Source Horn | diyAudio
Scott Hinson’s MEH
The Design
Designing this project involved plenty of trial and error with drivers, designs, and Hornresp parameters. First I was going to build a 3-way MEH using four 4” drivers and two 10” drivers per horn + big subs using 15” drivers. However, when I discussed this with my better half, she wasn’t happy with the big size. So I changed it to a more compact design: 30x30cm 2-way MEHs paired with subwoofers.
For the 3-way MEH I got ideas and insights from Syn 9/Syn 10 and Cosynes, Scott Hinson’s MEH and SynTripPs. After deciding to go with a smaller horn, I began exploring more compact designs, such as: Two way synergy Horn, Portable Battery Powered MEH Build and others.
Size
Using Synergy Calc , I calculated the size and parameters for Hornresp. According to Bill Waslo: “with horns, bigger is better!”. While I would have preferred larger dimensions, I had to consider WAF, so I settled on a 30x30cm horn with an 80° coverage angle and horizontal pattern control to 850 Hz. After reading this discussion I changed the S1 value to 5.06 to match the CDs opening area to get a more precise Hornresp Simulation..
Drivers
Hornresp is a fantastic tool for modeling speakers, big thanks to David McBean for his contributions! After countless evenings testing various drivers and parameters, I settled on the following components:
Compression Driver - FaitalPRO HF108 (8Ω) I chose it because it works well in short horns and wide dispersion waveguides and people seem to like it a lot. The recommended crossover is 1300 Hz, which is what I’ll go with in my design.
Midrange - 2x FaitalPRO 4FE35 (8Ω) in parallel - they simulated well in Hornresp and have been used in some MEH builds before.
Hornresp parameters
3d printed horn
The inner section of the horn (shown in light grey in the 3D rendering) will be 3D-printed, while the outer flare will be constructed from 2 sheets of 19mm MDF with a dispersion angle of 130 degrees
The HF108 compression driver has a 31-degree exit angle, so the horn starts with a matching 31-degree angle and gradually transitions to an 80-degree angle at the midrange entry point.
To minimize unexpected cancellation notches, the inner corners of the horn are smoothed with 2mm rounded edges.
Mid driver Port location:
From Why Synergy horns?:
I’m crossing between the mid and the compression driver (CD) at 1300 Hz, which means the port holes for the mid drivers should be within 6.596 cm (calculated as 343/1300/4) of the CD’s exit.
I’ve been wondering if the critical distance is measured from the mid ports to the CD’s acoustic diaphragm or its exit. The CD’s exit seems to work well in previous designs posted here, so I decided to go with that. This approach also simplifies placement by allowing the ports to be positioned farther out.
To ensure I stayed within the critical distance, I decided to shorten L12 slightly (the distance between the CD’s exit and the plane of the mid-entry ports). L12 is 4.28 cm, meaning the centre of the mid-entry port is 5.84 cm from the centre of the CD’s exit, so it’s well within the required 6.596 cm for the crossover.
The circumference of the cross-sectional area at the tap-in point is calculated as 6.531*4=26.124, which is close to the wavelength of 1300 Hz.
However, when I model it in Hornresp, the cancellation notch appears well above 1300 Hz, and the mids start to roll off around 2000 Hz. I can increase the distances well above 6.6 cm before I get the cancelation notch near 1300 Hz. I’m not sure if I’ve missed something in my calculations and the measurements may differ when I measure the build speakers.
Mid driver Vrc:
I made the Vrc (closed rear chamber volume) fairly small 2 L in total (1L per driver). I still haven’t figured out how I will limit the chamber volume. Using tubes like those in the Cosynes would be challenging due to the distance between the mids and the compression driver.
Mid driver Vtc:
I didn’t feel like I needed to minimize the Vtc (throat chamber volume) as the mids can play high enough frequency already. Making it smaller using cone plugs seems more beneficial with bigger woofers (like on the SynTripPs) and also the B&C 4NDF34 which have been used in some designs. For now I’ve estimated 50cc per driver, but will measure the volume when I receive them. I might adjust the sizing after doing the final calculations with the correct volume.
Mid driver port size:
There are 2 entry ports per driver, 4 in total. The entry points are frustrumised, 2.76 cm in diameter closest to the driver and 1.95 on the inside of the horn, which translate to Ap1 of 24 cm² and Ap2 of 12 cm².
The ports are relatively small, with port velocity exceeding 17 m/s when played above 105 dB below 200 Hz. These are meant for home hi-fi use, so I don’t plan to play them too loud. I also don’t want to make them too big, so they affect the CD’s output. The ports are placed next to the corners to minimise the effect they have on the CD.
Vertical drivers:
This is something I haven’t seen mentioned often, and it seems to be overlooked in many MEH designs. I will place all the drivers vertically, on the side walls of the horn, to avoid driver sag.
Ported or sealed box:
While I was designing the 3-way MEH with 2x 10” woofers I tried modeling the low drivers in both ported and sealed box. I ended up choosing sealed after reading Arts comment from the SynTripP thread.
Subwoofers:
I haven’t decided on the subwoofers yet.
I’m considering adding two subs within the same enclosure as side-firing woofers in a push-push alignment. For example, two GRS 8SW-4HE drivers in a sealed configuration with a ca 42L volume. Here is a promising recommendation for these woofers.
If I go with this approach, I might decrease the vertical coverage angle of the MEH horn to 60 degrees to make space for the woofers below the horn. I guess it would be good idea to have the woofers close to the horn, within ¼ wavelength of the crossover frequency, but have also read that it doesn’t matter very much for frequencies below 100 Hz.
Adding the subs in the same enclosure would significantly increase the height of the enclosure, which may not pass the WAF. Alternatively, I could build a separate subwoofer placed approximately 1.5 meters away
Is it better to integrate side-firing subwoofers within the same enclosure or should I make a separate enclosure, which would need to be ca 1.5m away? I’d appreciate any feedback or suggestions on driver selection!
Amplifier and DSP:
As I don’t own any of the parts needed I have the opportunity to build the whole system from scratch.
The TPA3255/51 amps seem to offer great value for the money.
I’m looking into: Fosi ZA3, AIYIMA A70, Topping PA5 II and the upcoming 3e audio amps. I haven’t decided yet and would appreciate any recommendations.
Finding a DSP solution that fits the budget has been tricky. High-quality DSPs can be expensive, while the cheaper options often come with limitations.
I’ve decided to go with a Raspberry Pi 5 running CamillaDSP. For the DAC, I’ll start with the cheapest option: the AliExpress cards mentioned in this guide. RPi 5 Quad Stereo Sound with PCM5102A – Simple DIY Electronic Music Projects. User dptucunduva has had good results with it.
The reasons I chose it are:
It’s cheap and has good potential for upgrades. I can switch out the DAC module for a proper sound card like the Motu Ultralite mk5.
It’s a very flexible system, the Raspberry Pi can act as a streamer and allows for lots of add-ons like a remote controller, Those who use CamillaDSP seem very happy with it.
HiFiBerry DAC, which uses the same DAC chip seems to be decent according to the measurements here. I’m not expecting any fantastic results but see it as a cheap solution that has all the active crossover functions needed.
Next steps:
The CD and mid-drivers are on their way, and I plan to begin 3D printing the horn in early January. In the meantime I’ll focus on refining the horn design, adding mounting holes, figure out how to do the right vrc size. I also need to decide which amplifiers to use and start building the Raspberry Pi DSP. Additionally, I’ll work on designing the subwoofers and determining whether side-firing woofers are the best option.
Any suggestions or input would be greatly appreciated!
How to - Distortion Measurements with REW
- By xrk971
- Software Tools
- 1945 Replies
I have been using the excellent and free software package called REW and a sound interface card (or DAC/ADC) to measure my amps for years now. It’s fast, easy and really costs nothing if you have a sound interface already. REW is normally used for measurement of speakers with microphones, however, it’s interface, GUI, and math engine are top-notch and lend themselves to an excellent amp measurement tool. I have been asked numerous times via PM’s to assist DIYA members make their own measurement setup using REW. Recently, I was asked again in the M2X thread when I chimed in that one doesn’t need expensive dedicated distortion analyzers from HP/Agilent/etc. all you need is a decent sound interface and REW. Plus a dummy load resistor and some wiring.
First of all, I want to thank member John Mulcahy, the author of REW - what a wonderful gift he has given to the DIY community. He is also always there to answer as technical question on REW.
So what can a sound card and REW do for you in terms of audio distortion measurement? Here is a typical FFT spectrum that I took using a $99 Focusrite Solo USB sound interface and REW with the Alpha 20 amp. This is 2.83vrms into 8ohms:
The plot above tells us several things about this amp: it has a dominant second harmonic distortion signature (sweet sounding), it has a little third order (gives it some bite), it’s devoid of higher orders, or higher odd orders specifically, which can sound fatiguing; it has an overall low level of total harmonic distortion (as seen in onset window); the mains noise at 60Hz and 120Hz is essentially zero - that is, it is very quiet and hum free; finally, the noise floor is about -110dB below the signal so it has very black blacks.
How hard is it to take this data? Well that’s the purpose of this thread. To show you how easy it is to do.
Another example of how REW can tell you how to tune your amp to achieve a harmonic distortion profile of interest. Some amps have this variable knob that lets you tune the type and level of distortion to your liking:
DLH Amplifier: The trilogy with PLH and JLH amps
Here is an example of measuring a preamp driving a 7k ohm load, this is the Aksa Lender putting out 20Vpp into 7kohms:
So where to begin? Let’s start with getting a copy of REW on your computer. Works on PC or Mac but I am only familiar with the PC version. Go here to download REW, and while you are at it, please donate some funds to John Mulcahy to continue his excellent work.
REW - Room EQ Wizard Room Acoustics Software
Once you install it, install software or drivers for your sound interface. I have used even the built in sound card in a PC to do this and it can work. However, those are generally very noisy and you won’t get the nice -130dB noise floor that some standalone interfaces can achieve. I personally use a Focusrite Solo (2nd gen) and 2i4 (2nd gen). They both have the same ADC’s but the 2i4 has a front end that is more flexible. I also think it has slightly better low noise characteristics. But you can use any sound card as long as it is supported by REW - and that includes any Java supported card. I haven’t found one that is not supported yet.
Next step is to connnect your interface by plugging in the USB cable, for example. Some of you might have other interfaces. The go into the setup menu and configure the sound interface. I typically the non-ASIO interface as I find that more finicky to work. Then choose your input device as your sound card and your output device as your sound card. Choose input and output amplitude to be “Master” and set to amplitude of 1.0 - this lets the full signal be generated by the sine wave generator and the full signal be captured by the ADC.
On the input settings choose the channel where you will connect your amp’s load resistor. Channel 1 is typically the “Left” channel and channel 2 is “Right”.
At this point you can see what the inherent self noise of your sound interface is without anything connected. Click on the “RTA” button along the top. In this dialog, click on the gear to adjust the settings. I use something like this:
You can try other settings. Making the averages smaller like 0.88 exponential and choosing 32k points will give you almost real-time updates to the FFT. You need to click on the span button to set your range of measurement from say 20Hz to 20kHz. On the vertical scale button on upper left click on dBFS. Then click on the red button to acquire your FFT spectrum.
You will see a relatively flat spectrum (hopefully) but this will tell you what the noise floor of your setup is. A cheap built in sound card on my pc only gets -110dB. The Focusrite get -130dB. There are ways to achieve better noise floor and much is discussed in threads elsewhere. For many of our SS amps around here the typical noisefloor of the Focusrite is fine as distortion is typically no lower than -100dB abd typically -80dB or so.
This is all fine and good but how do we measure distortion in our amps? Well we first need to make a dummy load resistor to simulate your speaker load. You need a power resistor with the same impedance as your amp that you are testing. Typically 8ohms or 4ohms. It also needs to handle the amp’s power output. A good one is a metal shelled 25w resistor mounted to a heat sink.
Here is an example of one with the wires you will need to make to connect it to a sound interface:
Here is a sketch of how to connect your load resistor to the sound interface and the PC:
For measurements of amp power up to 1w (8Vpp) it’s ok to connect the dummy load to your sound card directly. However, if your amp ever had a burp and hits the interface input preamp with too much voltage it can fry the input stage. I would recommend adding a ~10:1 voltage divider using a 20k and 2k resistor and taking the middle node attenuated output as the signal to your sound interface.
Edit May 10, 2024: circuit for floating balanced input needed for bridged class D amps here https://www.diyaudio.com/community/...ion-measurements-with-rew.338511/post-5925805
Also, if you are using Class D amp, you need a steep filter to keep the high frequency noise out while not distorting the low frequency to prevent aliasing the data. I used the filter suggested by Voltwide/Bucksbunny here: https://www.diyaudio.com/community/...ion-measurements-with-rew.338511/post-6714709
Depending on your sound interface, they may be good for 20v max input so that would give you pretty good protection. Never put full 25wrms (40Vpp) into your sound interface unless you want to fry it.
Now you need a way to generate your 1kHz (or whatever frequency you like) excitation sinewave. You can use the audio output of your sound card and the built in generator in REW. Then connect the audio out of the sound interface to your amp’s input. Adjust the level using the amp’s volume knob if you have one or the knob built into the Focusrite or the level in the generator interface.
Another way is to use an independent reference frequency source. A dedicated low noise high precision generator from HP is expensive. You can use a digital audio player with a good DAC as your source. I use a Cayin N3 which has the excellent AKM4490 DAC. Create a 1kHz sound file in lossless flac format using a program like audacity. Then play that into your amp as the excitation source. Those has the benefit of decoupling your source from your measurement to avoid ground loops. Especially if the source is a battery powered DAP. It’s also typically quieter.
So now connect your audio source to your amp, connect your amp to your dummy load, connect your audio interface to the dummy load, and connect a DVM to the dummy load and set to AC volts. Increase or decrease the amplitude of the 1kHz sine wave until the DVM reads 2.83vac. That’s same as 1w into 8ohms. A typical standard at which distortion measurements are taken.
That’s all for now. I will update later as I did this post with my phone and will get back with more details. But this should get many of you started.
Update June 3, 2019: Here is a loopback using Focusrite Solo gen2 and Akitika 2ppm 1kHz oscillator at 1.0Vpp into 10k:
Update Sept 24, 2020: member Wtnh made a very nice and useful schematic and connection diagram for us to use. Although he used an EMU sound interface, a lot of it applies to other sound interfaces as well (like Focusrite, or any other with combo XLR/TRS balanced inputs):
First of all, I want to thank member John Mulcahy, the author of REW - what a wonderful gift he has given to the DIY community. He is also always there to answer as technical question on REW.
So what can a sound card and REW do for you in terms of audio distortion measurement? Here is a typical FFT spectrum that I took using a $99 Focusrite Solo USB sound interface and REW with the Alpha 20 amp. This is 2.83vrms into 8ohms:
The plot above tells us several things about this amp: it has a dominant second harmonic distortion signature (sweet sounding), it has a little third order (gives it some bite), it’s devoid of higher orders, or higher odd orders specifically, which can sound fatiguing; it has an overall low level of total harmonic distortion (as seen in onset window); the mains noise at 60Hz and 120Hz is essentially zero - that is, it is very quiet and hum free; finally, the noise floor is about -110dB below the signal so it has very black blacks.
How hard is it to take this data? Well that’s the purpose of this thread. To show you how easy it is to do.
Another example of how REW can tell you how to tune your amp to achieve a harmonic distortion profile of interest. Some amps have this variable knob that lets you tune the type and level of distortion to your liking:
DLH Amplifier: The trilogy with PLH and JLH amps
Here is an example of measuring a preamp driving a 7k ohm load, this is the Aksa Lender putting out 20Vpp into 7kohms:
So where to begin? Let’s start with getting a copy of REW on your computer. Works on PC or Mac but I am only familiar with the PC version. Go here to download REW, and while you are at it, please donate some funds to John Mulcahy to continue his excellent work.
REW - Room EQ Wizard Room Acoustics Software
Once you install it, install software or drivers for your sound interface. I have used even the built in sound card in a PC to do this and it can work. However, those are generally very noisy and you won’t get the nice -130dB noise floor that some standalone interfaces can achieve. I personally use a Focusrite Solo (2nd gen) and 2i4 (2nd gen). They both have the same ADC’s but the 2i4 has a front end that is more flexible. I also think it has slightly better low noise characteristics. But you can use any sound card as long as it is supported by REW - and that includes any Java supported card. I haven’t found one that is not supported yet.
Next step is to connnect your interface by plugging in the USB cable, for example. Some of you might have other interfaces. The go into the setup menu and configure the sound interface. I typically the non-ASIO interface as I find that more finicky to work. Then choose your input device as your sound card and your output device as your sound card. Choose input and output amplitude to be “Master” and set to amplitude of 1.0 - this lets the full signal be generated by the sine wave generator and the full signal be captured by the ADC.
On the input settings choose the channel where you will connect your amp’s load resistor. Channel 1 is typically the “Left” channel and channel 2 is “Right”.
At this point you can see what the inherent self noise of your sound interface is without anything connected. Click on the “RTA” button along the top. In this dialog, click on the gear to adjust the settings. I use something like this:
You can try other settings. Making the averages smaller like 0.88 exponential and choosing 32k points will give you almost real-time updates to the FFT. You need to click on the span button to set your range of measurement from say 20Hz to 20kHz. On the vertical scale button on upper left click on dBFS. Then click on the red button to acquire your FFT spectrum.
You will see a relatively flat spectrum (hopefully) but this will tell you what the noise floor of your setup is. A cheap built in sound card on my pc only gets -110dB. The Focusrite get -130dB. There are ways to achieve better noise floor and much is discussed in threads elsewhere. For many of our SS amps around here the typical noisefloor of the Focusrite is fine as distortion is typically no lower than -100dB abd typically -80dB or so.
This is all fine and good but how do we measure distortion in our amps? Well we first need to make a dummy load resistor to simulate your speaker load. You need a power resistor with the same impedance as your amp that you are testing. Typically 8ohms or 4ohms. It also needs to handle the amp’s power output. A good one is a metal shelled 25w resistor mounted to a heat sink.
Here is an example of one with the wires you will need to make to connect it to a sound interface:
Here is a sketch of how to connect your load resistor to the sound interface and the PC:
For measurements of amp power up to 1w (8Vpp) it’s ok to connect the dummy load to your sound card directly. However, if your amp ever had a burp and hits the interface input preamp with too much voltage it can fry the input stage. I would recommend adding a ~10:1 voltage divider using a 20k and 2k resistor and taking the middle node attenuated output as the signal to your sound interface.
Edit May 10, 2024: circuit for floating balanced input needed for bridged class D amps here https://www.diyaudio.com/community/...ion-measurements-with-rew.338511/post-5925805
Also, if you are using Class D amp, you need a steep filter to keep the high frequency noise out while not distorting the low frequency to prevent aliasing the data. I used the filter suggested by Voltwide/Bucksbunny here: https://www.diyaudio.com/community/...ion-measurements-with-rew.338511/post-6714709
Depending on your sound interface, they may be good for 20v max input so that would give you pretty good protection. Never put full 25wrms (40Vpp) into your sound interface unless you want to fry it.
Now you need a way to generate your 1kHz (or whatever frequency you like) excitation sinewave. You can use the audio output of your sound card and the built in generator in REW. Then connect the audio out of the sound interface to your amp’s input. Adjust the level using the amp’s volume knob if you have one or the knob built into the Focusrite or the level in the generator interface.
Another way is to use an independent reference frequency source. A dedicated low noise high precision generator from HP is expensive. You can use a digital audio player with a good DAC as your source. I use a Cayin N3 which has the excellent AKM4490 DAC. Create a 1kHz sound file in lossless flac format using a program like audacity. Then play that into your amp as the excitation source. Those has the benefit of decoupling your source from your measurement to avoid ground loops. Especially if the source is a battery powered DAP. It’s also typically quieter.
So now connect your audio source to your amp, connect your amp to your dummy load, connect your audio interface to the dummy load, and connect a DVM to the dummy load and set to AC volts. Increase or decrease the amplitude of the 1kHz sine wave until the DVM reads 2.83vac. That’s same as 1w into 8ohms. A typical standard at which distortion measurements are taken.
That’s all for now. I will update later as I did this post with my phone and will get back with more details. But this should get many of you started.
Update June 3, 2019: Here is a loopback using Focusrite Solo gen2 and Akitika 2ppm 1kHz oscillator at 1.0Vpp into 10k:
Update Sept 24, 2020: member Wtnh made a very nice and useful schematic and connection diagram for us to use. Although he used an EMU sound interface, a lot of it applies to other sound interfaces as well (like Focusrite, or any other with combo XLR/TRS balanced inputs):
Attachments
Power switch specification - have I chosen the right one?
- By TMK7
- Power Supplies
- 4 Replies
Hi all,
I am building a class D power amplifier and got a bit confused on how to read the specification on the power switch and whether it will actually work for the purpose.
This is a 200W mono construction, 400VA/40V toroid transformer with 200 uF filter caps and a 2 second softstart from the late Newclassd solution
The power switch I have bought is specified to 10A 250V, but got a bit confused on the fuse power specification on 2W for one-pole and 1.6W for 2-pole. Have I bought the wrong switch for this application? Any suggestions to what spec I need - both for the switch and what fuse to use 🙂
The switch: https://docs.rs-online.com/dd66/0900766b81148d4e.pdf
and the specification sheet:
I am building a class D power amplifier and got a bit confused on how to read the specification on the power switch and whether it will actually work for the purpose.
This is a 200W mono construction, 400VA/40V toroid transformer with 200 uF filter caps and a 2 second softstart from the late Newclassd solution
The power switch I have bought is specified to 10A 250V, but got a bit confused on the fuse power specification on 2W for one-pole and 1.6W for 2-pole. Have I bought the wrong switch for this application? Any suggestions to what spec I need - both for the switch and what fuse to use 🙂
The switch: https://docs.rs-online.com/dd66/0900766b81148d4e.pdf
and the specification sheet:
My best discrete preamp with 3 transistors
- By lineup
- Analog Line Level
- 26 Replies
Let me start to say that this is only simulation with SPICE.
But I have no doubt this amplifier should do very well for real.
I challenge you to do something like it or even better 🙂
Design goals:
1. Fully discrete
2. Max 3 transistors
3. Voltage gain 4-5
4. Load 1Vrms into 4.7kOhm
5. Regulated 12V supply
Result in SPICE:
1. Voltage gain 4.6
2. THD 0.00011%
3. Frequency response 5Hz-300kHz -3dB
But I have no doubt this amplifier should do very well for real.
I challenge you to do something like it or even better 🙂
Design goals:
1. Fully discrete
2. Max 3 transistors
3. Voltage gain 4-5
4. Load 1Vrms into 4.7kOhm
5. Regulated 12V supply
Result in SPICE:
1. Voltage gain 4.6
2. THD 0.00011%
3. Frequency response 5Hz-300kHz -3dB
1st MTM build
This will be my 2nd go around at building multi-way speakers and have decided to try a MTM configuration. When designing the crossovers, is there anything I need to do differently than I would do in a TW 2 way crossover? The mids will both be the same make/ model. I've ran some sims through xsim and removed one of the 2 mids after building one to see if it reacted. It did but not in the way I had expected. The SPL actually went up when disconnecting the 2nd driver. 1st pic is with 1 mid. Pic below it has both hooked up. Would that be normal?
Nick Sukhov SU-XXI MM Phono stage -85 dBA SN ratio...
- By Artmaster
- Vendor's Bazaar
- 491 Replies
Attachments
Another 3d printed MEH
- Multi-Way
- 45 Replies
I have been printing another large MEH. Finally got it finished and vaguely measured. It is 630mm wide and 360mm tall. The horn is 350mm long without the comp
Here are the measurements:
The measurements were taken with the mic at the mouth in a small room as in the image above so they aren't ideal but I will try and get some better measurements soon.
With the sims I had managed to get it up to around 2khz however it drops off rapidly above 1.3khz. I have managed to get smaller drivers up to 2khz before so thinking it is cancellations across the cone?
I might try doing some modelling in Akabak of just the front chamber and taps to see what I end up with.
Here are the measurements:
The measurements were taken with the mic at the mouth in a small room as in the image above so they aren't ideal but I will try and get some better measurements soon.
With the sims I had managed to get it up to around 2khz however it drops off rapidly above 1.3khz. I have managed to get smaller drivers up to 2khz before so thinking it is cancellations across the cone?
I might try doing some modelling in Akabak of just the front chamber and taps to see what I end up with.
Audison SR1DK output problem
Hello everyone,
I have an Audison SR1DK with a weird issue. The output at startup is not at full power and it gradually rises to full power. Changing the gain does not affect it much, and the signal is clipped when the gain passes a certain threshold.
Also, does anyone know the value of this capacitor (C128)?
I have an Audison SR1DK with a weird issue. The output at startup is not at full power and it gradually rises to full power. Changing the gain does not affect it much, and the signal is clipped when the gain passes a certain threshold.
Also, does anyone know the value of this capacitor (C128)?
Completely wrong DC bias on output stage
- By iamanerd
- Solid State
- 32 Replies
Hi everyone,
I'm trying to build this amplifier based on the Sanyo STK465 amplifying module (I attached the originals down below).
And this is my version:
I simulated this circuit using LTspice and everything works as I expected. I attached the simulation down below.
The problem is that when I build it in real life the DC bias point of the output stage is not going to 0V DC. It sits close to the positive rail and I can't figure out the reason. I can't proceed further until I get the DC bias point right, so I'm stuck here.
I'm currently using a 10K resistor as the load so i don't fry the output transistors, but the problem persists even with a 10 ohm load. R6 and R7 are there to protect the output transistors as well.
What I tried:
I'm at a loss. Why doesn't the VAS stage bias the Sziklai pairs in the output stage correctly? Do you have any suggestions? Thank you very much for your time and for your help.
I'm trying to build this amplifier based on the Sanyo STK465 amplifying module (I attached the originals down below).
And this is my version:
I simulated this circuit using LTspice and everything works as I expected. I attached the simulation down below.
The problem is that when I build it in real life the DC bias point of the output stage is not going to 0V DC. It sits close to the positive rail and I can't figure out the reason. I can't proceed further until I get the DC bias point right, so I'm stuck here.
I'm currently using a 10K resistor as the load so i don't fry the output transistors, but the problem persists even with a 10 ohm load. R6 and R7 are there to protect the output transistors as well.
What I tried:
- I checked the supply rails and they are fine. They come from a dual power supply I built which uses L7812CV and L7912CV linear regulator.
- I checked the connections a thousand times.
- Tried to remove all capacitors (excluding the decoupling ones and the compensation capacitor C4) in order to focus on the DC response only.
- The circuit was originally built on a breadboard. I've now soldered the amplifier on a perf board, while the rest of the circuit (the input section, the output filter, the feedback) is still on the breadboard.
- I put a 10K potentiometer on the emitter of Q5 and tried to trim it (therefore decreasing the gain of the VAS stage) until I got 0V DC at the output. I couldn't get it to work: as I got closer and closer to zero, the output flipped to the negative rail; I then trimmed the pot on the opposite direction, and the output flipped back to the positive rail. I think this happens because Q5 gets shut completely off, causing the output to swing to the negative rail.
I'm at a loss. Why doesn't the VAS stage bias the Sziklai pairs in the output stage correctly? Do you have any suggestions? Thank you very much for your time and for your help.
Attachments
Measuring audio transformer impedance with LCR meter
- By Mrdouble
- Electronic Design
- 5 Replies
I'm just trying to figure out how to use my fancy LCR meter. All I want to do is measure the impedance of a 1:1 audio transformer and compare against the data sheet.
Data sheet says impedance should be 15K with a 600 ohm load but the LCR is spitting out 3.2k. I have bought the handheld DE-5000 to verify the first LCR but ability meters agree.
All I have to do is hook a 600ohm load up to the secondary, right? I'm totally confused
Data sheet says impedance should be 15K with a 600 ohm load but the LCR is spitting out 3.2k. I have bought the handheld DE-5000 to verify the first LCR but ability meters agree.
All I have to do is hook a 600ohm load up to the secondary, right? I'm totally confused
For Sale 2 Pairs of TW29TXN-B
I am selling 2 pairs of TW29TXN-B satoti tweeters.
Selling as i am moving to be tweeters
Looking to get $300 per pair
Buyer Pays shipping and paypal
Selling as i am moving to be tweeters
Looking to get $300 per pair
Buyer Pays shipping and paypal
2stageEF high performance class AB power amp / 200W8R / 400W4R
- By astx
- Solid State
- 3256 Replies
Attachments
Thoughts about retirement...
- By M Gregg
- The Lounge
- 1124 Replies
Just an interest,
How old do you want to be when you retire?
Any thoughts about jacking in and getting the "Good Life" or is it looking a bit doggy..
Any pitfalls from those that already have...
Thought it might be fun to see what the thoughts are..😱 or
Victor meldrew always comes to mind....
http://www.youtube.com/watch?v=c1qs_eFRXqs&feature=related
Regards
M. Gregg
How old do you want to be when you retire?
Any thoughts about jacking in and getting the "Good Life" or is it looking a bit doggy..
Any pitfalls from those that already have...
Thought it might be fun to see what the thoughts are..😱 or
Victor meldrew always comes to mind....
http://www.youtube.com/watch?v=c1qs_eFRXqs&feature=related
Regards
M. Gregg
Lazy Singing Bush
I forgot how long I have these pcbs; heck, even added (just for giggles) one small cap, just to have a reason to make new gerbers 
Anyway, N-MOS/Schaded N-MOS/SIT source follower, loaded with P-MOS in Mu-Follower arrangement, blatant shameless flipped Xerox of Papa's BAF 2015 amp Mu part
Mosfets are IXYS hockey pucks
SIT can be THF51, 2SK180, 2SK182
Single rail supply, GND up, neg 60Vdc down (remember that GND is State of Mind - I did use +/-30Vdc PSU from my T-Bed 2 accordingly wired, without using center rail)
Iq 3A2
Necessary pictorial info about "main" pcb
(late) edit on Jan 25. 2024. - change of Mu resistors values, as per Ben Mah's suggestion - post #17, https://www.diyaudio.com/community/threads/lazy-singing-bush.388164/post-7069779
in short - 0R2 at SIT side, 0R3 at puck side
Anyway, N-MOS/Schaded N-MOS/SIT source follower, loaded with P-MOS in Mu-Follower arrangement, blatant shameless flipped Xerox of Papa's BAF 2015 amp Mu part
Mosfets are IXYS hockey pucks
SIT can be THF51, 2SK180, 2SK182
Single rail supply, GND up, neg 60Vdc down (remember that GND is State of Mind - I did use +/-30Vdc PSU from my T-Bed 2 accordingly wired, without using center rail)
Iq 3A2
Necessary pictorial info about "main" pcb
(late) edit on Jan 25. 2024. - change of Mu resistors values, as per Ben Mah's suggestion - post #17, https://www.diyaudio.com/community/threads/lazy-singing-bush.388164/post-7069779
in short - 0R2 at SIT side, 0R3 at puck side
Attachments
For Sale 3 pairs of heatsinks for ampilifiers (Europe)
- By Groundloops
- Swap Meet
- 1 Replies
Some pairs of heatsinks for amplifiers, salvaged from dead AVRs:
Two pairs 18,7 x 15,3 x 4,0 cm
One pair 19,7 x 13,5 x 5,0 cm
Make me a fair offer ...
Two pairs 18,7 x 15,3 x 4,0 cm
One pair 19,7 x 13,5 x 5,0 cm
Make me a fair offer ...
Bliesma M74A/B/S buzzing fix
I noticed on some of my Bliesma M74A mids there was an intermittent buzzing sound around Fs (400 - 500 hz) which disappeared when I put pressure on the small WG front flange portion.
Underneath the foam flange sealing gasket on the under side of the driver, there are 4 small allen head screws. I've discovered some these screws have bottomed out in the holes before the full clamping force is imparted on the VC ring asy that is sandwiched between the two metal parts. I did find some excess powerdercoat inside the screw holes, keeping the screws from seating at full depth inside the holes. Chasing the threads with a bottoming tap would likely be the most correct way to fix this, but I don't have an M3/0.5 bottoming tap or thread chaser, so I had to improvise and came up with the following simple fix...
I've inserted a 0.5 mm stainless steel washer under each of the 4 flange screws, which still allows the head of the screw to sit flush with the flange surface.
Important - only deal with one screw at a time !!! You don't want to risk the VC going out of alignment, so be careful. These are precisely aligned components you're dealing with here.
There is a light thread locking compound on these threads, so go slowly and carefully when removing the screws to avoid thread damage. Tighten the screws back to about 4 - 5 inch lbs. (If you need an exact torque figure, this is about right).
You dont need thread locker if you tighten the screws down evenly. Once you mount the driver, it will automatically be compressed together by the baffle screws, so there won't be any chance of the 4 small screws backing out on their own.
The small buzz was completely cured with this fix. It was noticeable on 2 out of my 4 M74As. I'm likely being very picky here, but I didn't want to risk a VC misalignment or shifting with these screws having an uneven clamp load on the VC asy. Again, once you mount the driver, it should no longer be a concern.
Underneath the foam flange sealing gasket on the under side of the driver, there are 4 small allen head screws. I've discovered some these screws have bottomed out in the holes before the full clamping force is imparted on the VC ring asy that is sandwiched between the two metal parts. I did find some excess powerdercoat inside the screw holes, keeping the screws from seating at full depth inside the holes. Chasing the threads with a bottoming tap would likely be the most correct way to fix this, but I don't have an M3/0.5 bottoming tap or thread chaser, so I had to improvise and came up with the following simple fix...
I've inserted a 0.5 mm stainless steel washer under each of the 4 flange screws, which still allows the head of the screw to sit flush with the flange surface.
Important - only deal with one screw at a time !!! You don't want to risk the VC going out of alignment, so be careful. These are precisely aligned components you're dealing with here.
There is a light thread locking compound on these threads, so go slowly and carefully when removing the screws to avoid thread damage. Tighten the screws back to about 4 - 5 inch lbs. (If you need an exact torque figure, this is about right).
You dont need thread locker if you tighten the screws down evenly. Once you mount the driver, it will automatically be compressed together by the baffle screws, so there won't be any chance of the 4 small screws backing out on their own.
The small buzz was completely cured with this fix. It was noticeable on 2 out of my 4 M74As. I'm likely being very picky here, but I didn't want to risk a VC misalignment or shifting with these screws having an uneven clamp load on the VC asy. Again, once you mount the driver, it should no longer be a concern.
AULA02014 8" + Celestion CDX1 CD with Harsch XO sorta
- By AdamThorne
- Multi-Way
- 15 Replies
I bought these drivers back in end August I think it was, and I've finally got a box for 'em. I've measured up the in box response and played around with the results in XSIM. I still have to order XO parts, and do a final sand and finish on the boxes. But I thought I'd share where I'm at.
I kicked out a thread to discuss the drivers when I ordered them, it's https://www.diyaudio.com/community/threads/tymphany-aula02014-0006-pe-buyout.416365/
Woofer (buyout, NLA) is this 8" tymphany pro audio with a big honker magnet
https://www.parts-express.com/Tymph...-Paper-Cone-Woofer-8-Ohms-299-2265?quantity=1
I got 'em for $17 each!
Compression driver is Celestion CDX1-1446
https://www.parts-express.com/Celes...-Compression-Driver-8-Ohm-299-2257?quantity=1
This one is also a buyout but I think the same driver is available regular production.
I've got it on this JBL Selenium HM17-25 https://www.parts-express.com/Selen...al-Horn-60x40-1-3-8-18-TPI-264-308?quantity=1
I have modeled it up in 30 L and ported at 60 Hz. Software wanted to suggest smaller / higher, but I'm trying to get this thing to dig down far enough to cross to my sub. I have 3D printed a port according to geometry in this Harmon paper about optimizing ports. https://www.diyaudio.com/community/attachments/harman-port-study-pdf.893225/
I was trying to conceptualize how I'd put this speaker together, and I thought of trying to time-align the drivers, so I measured the acoustic offsets. The horn+tweeter came out 70mm behind the driver (mounting features in the same plane), which was more than I was expecting. I had a little thread to consider options about that https://www.diyaudio.com/community/...nique-for-horn-out-front.419357/#post-7851615 eventually I remembered that @xrk971 has a crossover topology that wants the tweeter a fair bit delayed WRT the woofer, and that's the Harsch XO, he's got a thread about it here - https://www.diyaudio.com/community/threads/s-harsch-xo.277691/. I was considering a 2kHz XO, and the delay according to the Harsch thing was 85mm, so another sheet of plywood for the woofer to sit on was just about right.
So that's about how I dreamed this one up! Here's how it looks...
Ah... every thread is better with pictures. I've got roundover I think it's 1" on the vertical corners. Boxes made of arauco ply 3/4" from Home Depot, I'm still trying to decide how I'm gonna finish them. I like the lines from the ply on front.
Ground plane, on-axis (spkr tilted down to point at the mic) 2m distance acoustic measurements look like this
THD is good on the woofer, and FR is fine to 3k, but I think that is a low baffle step from 100 to 500? Speaker is 12.5" wide. Anyway that shift ended up being around the upper of the two impedance peaks in low woofer response, that made it kinda tricky to correct passively. FR on the tweeter seems pretty nice, but measurement looks like kinda high 2nd order HD.
I've been fiddling with the XO sim to get something I like.... here's where I'm at.
Initial idea was to have the cross at 2k, but in the course if trying to make it work I have floated up from there. So I think my offset is actually a little too much, and my phase peak is a bit larger than it might have been.
If you go for this sort of XO, it is (quoted from XRK's thread)...
1. Set the low pass filter for the woofer as a 4th order Butterworth at central frequency, fc for the XO centerpoint.
2. Set the high pass filter for the tweeter as a 2nd order Bessel at fc.
3. Set the delay of the tweeter equal to 1/2 of the period of one cycle at fc.
4. Use all positive phase on woofer and tweeter.
Here's what I've learned: 2nd order -acoustic- roll off is pretty slow! 2nd order electrical is normally fine, but when you are looking at the acoustic rolloff that happens naturally that doesn't leave much space to put in electrical protection. So I ended up at higher F than I was initially targeting. It looks like 2nd order electrical on the CD but it's pretty low Q, that inductor is only helping out at lower frequencies. Impedance compensation on the CD can help you get the shape theory wants.
I think I've attached the XSIM file in case anyone wants to play along.
I'm looking forward to hearing these, but I haven't pulled the trigger on XO parts yet. Every time I buy parts a couple days later I'm like "you know what I SHOULDA done...?" so I'm still meditating on it.
What do you think?
- Adam
I kicked out a thread to discuss the drivers when I ordered them, it's https://www.diyaudio.com/community/threads/tymphany-aula02014-0006-pe-buyout.416365/
Woofer (buyout, NLA) is this 8" tymphany pro audio with a big honker magnet
https://www.parts-express.com/Tymph...-Paper-Cone-Woofer-8-Ohms-299-2265?quantity=1
I got 'em for $17 each!
Compression driver is Celestion CDX1-1446
https://www.parts-express.com/Celes...-Compression-Driver-8-Ohm-299-2257?quantity=1
This one is also a buyout but I think the same driver is available regular production.
I've got it on this JBL Selenium HM17-25 https://www.parts-express.com/Selen...al-Horn-60x40-1-3-8-18-TPI-264-308?quantity=1
I have modeled it up in 30 L and ported at 60 Hz. Software wanted to suggest smaller / higher, but I'm trying to get this thing to dig down far enough to cross to my sub. I have 3D printed a port according to geometry in this Harmon paper about optimizing ports. https://www.diyaudio.com/community/attachments/harman-port-study-pdf.893225/
I was trying to conceptualize how I'd put this speaker together, and I thought of trying to time-align the drivers, so I measured the acoustic offsets. The horn+tweeter came out 70mm behind the driver (mounting features in the same plane), which was more than I was expecting. I had a little thread to consider options about that https://www.diyaudio.com/community/...nique-for-horn-out-front.419357/#post-7851615 eventually I remembered that @xrk971 has a crossover topology that wants the tweeter a fair bit delayed WRT the woofer, and that's the Harsch XO, he's got a thread about it here - https://www.diyaudio.com/community/threads/s-harsch-xo.277691/. I was considering a 2kHz XO, and the delay according to the Harsch thing was 85mm, so another sheet of plywood for the woofer to sit on was just about right.
So that's about how I dreamed this one up! Here's how it looks...
Ah... every thread is better with pictures. I've got roundover I think it's 1" on the vertical corners. Boxes made of arauco ply 3/4" from Home Depot, I'm still trying to decide how I'm gonna finish them. I like the lines from the ply on front.
Ground plane, on-axis (spkr tilted down to point at the mic) 2m distance acoustic measurements look like this
THD is good on the woofer, and FR is fine to 3k, but I think that is a low baffle step from 100 to 500? Speaker is 12.5" wide. Anyway that shift ended up being around the upper of the two impedance peaks in low woofer response, that made it kinda tricky to correct passively. FR on the tweeter seems pretty nice, but measurement looks like kinda high 2nd order HD.
I've been fiddling with the XO sim to get something I like.... here's where I'm at.
Initial idea was to have the cross at 2k, but in the course if trying to make it work I have floated up from there. So I think my offset is actually a little too much, and my phase peak is a bit larger than it might have been.
If you go for this sort of XO, it is (quoted from XRK's thread)...
1. Set the low pass filter for the woofer as a 4th order Butterworth at central frequency, fc for the XO centerpoint.
2. Set the high pass filter for the tweeter as a 2nd order Bessel at fc.
3. Set the delay of the tweeter equal to 1/2 of the period of one cycle at fc.
4. Use all positive phase on woofer and tweeter.
Here's what I've learned: 2nd order -acoustic- roll off is pretty slow! 2nd order electrical is normally fine, but when you are looking at the acoustic rolloff that happens naturally that doesn't leave much space to put in electrical protection. So I ended up at higher F than I was initially targeting. It looks like 2nd order electrical on the CD but it's pretty low Q, that inductor is only helping out at lower frequencies. Impedance compensation on the CD can help you get the shape theory wants.
I think I've attached the XSIM file in case anyone wants to play along.
I'm looking forward to hearing these, but I haven't pulled the trigger on XO parts yet. Every time I buy parts a couple days later I'm like "you know what I SHOULDA done...?" so I'm still meditating on it.
What do you think?
- Adam
LM3886 chipamp feedback capacitor, yes or no?
I recently built an LM3886 amp, which I posted here. I read that some prefer the sound without the feedback capacitor (Ci on the datasheet) and was wondering why.
I know the DC offset will be higher without the capacitor and I plan on trying that the next time I open it up as I built mine with the feedback capacitor.
My guess would be different bass response but my training is in repair not engineering.
My question is: Can anyone describe the sound difference with and without the feedback capacitor?
Thanks.
I know the DC offset will be higher without the capacitor and I plan on trying that the next time I open it up as I built mine with the feedback capacitor.
My guess would be different bass response but my training is in repair not engineering.
My question is: Can anyone describe the sound difference with and without the feedback capacitor?
Thanks.
Lowther's New Premium Range
- By ghemml
- Full Range
- 70 Replies
Just got them delivered from the UK. Doing up a Lowther Acousta Enclosure for them pretty soon
What type of glue should be used to re-foam a metal Technics SBX500 honeycomb flat disc woofer?
- By 62vauxhall
- Multi-Way
- 9 Replies
I have spent several hours over the past two days searching for size/shape compatible surrounds. The most likely candidate so far are surrounds from Simply Speakers.
The surrounds attach to the underside of the SBX500 woofer discs which is a shiny metal surface - presumably aluminum.
Two years ago I attempted surround replacement to the undrside of 5" woofers with a poly cone and those surrounds coincidently came from Simply Speakers. That attempt was not successful due to the awkwardess of accessing the underside of the cone and the clear, fast setting adhesive provided by Simply Speakers. I think that clear glue was rubber based. There was not enough time for me to position the surround on the cone before the glue got too stickey to work with. They then sent me some conventional slower setting white glue.
I expect that gluing a surround to the underside of these Technics SBX500 woofer discs will be fiddly and somewhat time consuming. My question is will the conventional white' slower setting glue bond properly with the metal surface of the disc's inderside?
The attached photos are as they are now. The residual old surround material on the disc's underside is still in place. I am debating on attempted removal by blade & scraping or trying some type of solvent.
The surrounds attach to the underside of the SBX500 woofer discs which is a shiny metal surface - presumably aluminum.
Two years ago I attempted surround replacement to the undrside of 5" woofers with a poly cone and those surrounds coincidently came from Simply Speakers. That attempt was not successful due to the awkwardess of accessing the underside of the cone and the clear, fast setting adhesive provided by Simply Speakers. I think that clear glue was rubber based. There was not enough time for me to position the surround on the cone before the glue got too stickey to work with. They then sent me some conventional slower setting white glue.
I expect that gluing a surround to the underside of these Technics SBX500 woofer discs will be fiddly and somewhat time consuming. My question is will the conventional white' slower setting glue bond properly with the metal surface of the disc's inderside?
The attached photos are as they are now. The residual old surround material on the disc's underside is still in place. I am debating on attempted removal by blade & scraping or trying some type of solvent.
![PXL_20231013_150603919[1].jpg](/community/data/attachments/1131/1131011-ec80cfe043857b092db5b615a3ee8a71.jpg?hash=7IDP4EOFew)
![PXL_20231013_150639166[1].jpg](/community/data/attachments/1131/1131012-6f24748e38c9b5f04d87580c2e2e727d.jpg?hash=byR0jjjJtf)
![PXL_20231013_150704988[1].jpg](/community/data/attachments/1131/1131013-b839f7a3dc8fbfb58b11fb98e3c36e17.jpg?hash=uDn3o9yPv7)
Son of HF - Big Flower
Big Flower - the logical sequel to Horn Flower.
Initial design concept study outcome - the stands in the top picture is what I will end up with.
I have had a lot of fun and learnt much from HF. Some things with them are really desirable and I wanted to see if they could be improved on... and a reason to get a 3D printer 😉
Positives: Great clarity, resolution and timing.
Negatives: Small(er) stage (but very precise), limited low bass and som midrange anomalies (comb filtering) due to that the 4 woofers plays quite high (1400 Hz)
Also the bild quality of the "box" was pretty sketchy and despite the cool "hair", it probably generated quite a lot of diffraction.
So to keep the positives and remedy the negatives, enter the Big Flower.
Same concept but with improvements (finger crossed):
Potential new negatives:
The way they where designed and realised was by 3D modelling, molds printed from PETG and casting in concrete. I like concrete - its a varm, nice and strong material 🙂
It was obvious from the beginning that I could not get a printer to make the horns in one cast so it had to be divided and later glued together. I used Sikaflex 291 for this as it had proven very stable and strong when I built my concrete baffle Line Source. All drives were glued to the concrete and still sits there safely.
I did some simulation on speaker level for the Horn FLower which gave some hints that it could work and I think the result mimic'd the simulations quite well. Therefore I didn't do any for the BF because I don't think it is needed - concept works and I feel the new dimensioning can only be better. And then there is CamillaDSP 🙂
Recipe (for a pair):
So these will be prototypes and have a number of known "errors" already. They where identified during the path of design, both in modelling, casting and dry assembly but half way in I decided to go ahead with these "less perfect" aspects as I realised that it will take one round before I get them "perfect" (never!) anyways.
So what are these problems:
- It was harder than I could imagine to make a mold for a 60 degres part when it came to rotate a profile, make 6 of them and assemble them to a full circle unit. Sketchup could not do it. I got a plugin that was better but then I made som assumptions about how to get some room for the glue which I overestimated and got 5mm instead of 1. Next time, calculate please! 🙂 But I didn't find out until I had made 5 and then I decided to continue anyways.
- Perhaps I have made the concrete goods a little to thick - they have been called tanker stoppers 🙂 and they will be heavy - 40kg+ - a challenge for me to handle. Better have some help during first trials.
- and several minor improvements...
To date, I have all components ready to be assembled except the stands but they are waiting order confirmation.
I will continue posting about the assembly process, measuring and dialling in.
Tnx for reading - comments welcome.
//
Initial design concept study outcome - the stands in the top picture is what I will end up with.
I have had a lot of fun and learnt much from HF. Some things with them are really desirable and I wanted to see if they could be improved on... and a reason to get a 3D printer 😉
Positives: Great clarity, resolution and timing.
Negatives: Small(er) stage (but very precise), limited low bass and som midrange anomalies (comb filtering) due to that the 4 woofers plays quite high (1400 Hz)
Also the bild quality of the "box" was pretty sketchy and despite the cool "hair", it probably generated quite a lot of diffraction.
So to keep the positives and remedy the negatives, enter the Big Flower.
Same concept but with improvements (finger crossed):
- 260mm diameter horn -> 520mm
- 4pcs of 4" bass driver -> 6pcs of 5,5
- XO@1400 -> 800 (hopefully, 900/1k still ok)
- Larger volume per driver - > improved lows
- ATH G2 inspired horn at full width should decrease diffraction
- Lower XO should mean less LF drivers c-c distance interference
- Thanks to bass driver placement and stands/mount design, the LF drivers will be much closer to wall and with less c-c despite being larger,
Potential new negatives:
- Only one cavity so now the actual horn is a pressurised surface of the closed/infinite baffle - vibration?
- Using a 1,4" CD instead of a 1" might have impact on top octave
- Increased depth (5cm) gives a longer distance between LF drivers and horn mouth... integration...
- Heavy
The way they where designed and realised was by 3D modelling, molds printed from PETG and casting in concrete. I like concrete - its a varm, nice and strong material 🙂
It was obvious from the beginning that I could not get a printer to make the horns in one cast so it had to be divided and later glued together. I used Sikaflex 291 for this as it had proven very stable and strong when I built my concrete baffle Line Source. All drives were glued to the concrete and still sits there safely.
I did some simulation on speaker level for the Horn FLower which gave some hints that it could work and I think the result mimic'd the simulations quite well. Therefore I didn't do any for the BF because I don't think it is needed - concept works and I feel the new dimensioning can only be better. And then there is CamillaDSP 🙂
Recipe (for a pair):
- Qidi Q1 Pro
- PETG 4-5 rolls (quite some trails, mistakes and re-thinking done - 3rd time a charm...)
- 2x HF SB ROSSO-65CDN-T
- 12x LF SB15nac30-4
- 3,5 x 20kg bags of fibre reinforced floor levelling concrete: Weberflow 120 Reno DR
- 2 tubes of Sikaflex 291
- Div metal parts for the hanger force distribution box
- Rubber mat for horn/basket gasket
- 2x stands out of iron and concrete (of course! 😉)
- 1 pcs of 1977837 ATH A520G2 from Cults3D - even if I wasn't planning to print this exact horn I wanted to contribute to @mabat fantastic project and products. The profile was modified and simulated in ATH/VACS to give a bit wider dispersion.
- Dedicated electronic in one box - 230V in, wifi/eth and 2 pairs / ch of cabling. TBD...
So these will be prototypes and have a number of known "errors" already. They where identified during the path of design, both in modelling, casting and dry assembly but half way in I decided to go ahead with these "less perfect" aspects as I realised that it will take one round before I get them "perfect" (never!) anyways.
So what are these problems:
- It was harder than I could imagine to make a mold for a 60 degres part when it came to rotate a profile, make 6 of them and assemble them to a full circle unit. Sketchup could not do it. I got a plugin that was better but then I made som assumptions about how to get some room for the glue which I overestimated and got 5mm instead of 1. Next time, calculate please! 🙂 But I didn't find out until I had made 5 and then I decided to continue anyways.
- Perhaps I have made the concrete goods a little to thick - they have been called tanker stoppers 🙂 and they will be heavy - 40kg+ - a challenge for me to handle. Better have some help during first trials.
- and several minor improvements...
To date, I have all components ready to be assembled except the stands but they are waiting order confirmation.
I will continue posting about the assembly process, measuring and dialling in.
Tnx for reading - comments welcome.
//
Attachments
Speaker Fantasy Art
- By AE13
- The Lounge
- 134 Replies
For your viewing pleasure.
Speaker fantasy art.
Speaker fantasy art.
Aleph Jzm
- Pass Labs
- 700 Replies
What Is An Aleph Jzm?
The Nelson Pass designed First Watt Aleph J is a classic. @Zen Mod created this version of the Aleph J to make the project more approachable to newer builders while maintaining the characteristics of the original. For more advanced DIYers and those that like to experiment, there are options to use a variety of JFETs and customize the circuit to suit personal tastes. For those that don't know Zen Mod, he was gracious enough to post a video to introduce himself and share a few thoughts. It can be found on YouTube.
What’s In The kit?
All the electronics components needed to complete a pair of amplifier PCBs, including 8 matched JFETs.
What Is Needed To Complete The Full Project?
At this time, a complete kit including everything required to complete an amplifier is not available. You’ll need a power supply, chassis, wiring, and a few other parts. Everything you need can be purchased directly from the diyAudio store and well-known retailers world-wide. Suggestions are included in the build guide, and/or you can customize to your heart’s content.
What Skill Level Is Required?
This project is intended for intermediate to advanced DIYers. It may be the perfect project after an Amp Camp Amp. Newer builders willing to do a little studying should have no trouble following the build guide. However, it is critical that builders know how to identify parts from schematics, match those parts to PCB locations based on the silkscreen, and have good soldering skills. Most importantly, all builders are responsible for their own safety and must understand essential safety practices and precautions when dealing with mains powered electronics.
Feel free to review the Aleph Jzm Build Guide in advance if you're trying to determine if this project might be for you. The guide will continue to be updated. The Aleph Jzm Kit Build Support thread is also available if you have questions.
My Experience at a HIFI Audio Convention - AXPONA 2025
I asked the question some months back: How do our loudspeakers compare to expensive, high end, HIFI brand loudspeakers?"
I have answers.
The Short of it:
For those of you who do not want to read this entire write up I will be kind and put my summary up top in a bullet list. There was 3 of us who went. One musician, one loudspeaker builder, and one wife who only ever listens to the system the former two have and doesn't know how any of it works. We listened to 60 systems in one day. Back to back to back. We then came home and listened to my systems.
The BAD
The good
Lets go through one by one now (I am not going to include most of the bad ones. They sounded so bad I had to just get out of there. If it isn't listed below here and it was at the show, it sounded like crap):
This 4 way was great. It had dynamics and a lightness. Lows were washed out but it was still good
This was ATC. I hear people praise their old mid dome here so I checked them out.
This two way was horrendous. One of the worst speakers at the show. The driver on the table is what they were showing off. Do not buy this thing. It was sticky, like someone covered it in honey. I would guess in your house it'd be covered in dust within a couple weeks. Bad, just all bad.
Morel
These were great. The mid is the one up top and is ported. The woofers down below are also ported. These were REALLY good. I spoke with the engineer about how they don't measure or simulate well. He explained their motor design in detail. It will not simulate right because their design is so different. They have special software they have to use for their motor designs. The price point of morels now looks very attractive to me.
This one wasn't playing. I just thought it was a fun design with the dual AMTs in front of the woofer
MTM Illuminator design. What's not to like? Horrendous upper mid range. So sharp and attacking. Not good. Lows were good, not very dynamic. No idea what they cost but its too much. Feel like the designer dropped the ball here.
I will now never build a line array. This thing just sounded odd. Like a blade of people singing on the left and then a blade of instruments on the right. It was all washed out vertically. Hard to explain. Not a fan. None of us liked this, all of us thought it was just strange sounding. And not strange in a good way.
Full range driver build by Songer. Second best sounding full rang behind a Voight pipe Alpair 11 build. This thing was great. Good dynamics, good upper mid range, very nuetral, good dyanmics. It had it all. It is a giant full range so it beamed like crazy. Move your head left or right and the tone changes. But still very good.
I think these are called frugal horns? Big woofer and a compression driver. Engineer was in the room. Not my cup of tea but the BEST compression driver I have ever heard. He crosses these to the woofer at 700 hz. Pretty impressive and fluid, natural sound out of these. The big woofer lacked dynamics to say the least.
Triangle Art
These were bad. Like just plain bad. Maybe they would sound good if you were 60 feet back in a big room? Crazy directional. Everything sounded muddy. All looks, no beauty.
AudioVideo Artistry
******* AMAZING. What do the Accuton driver's sound like? ******* AWESOME. End game design right here. Nothing topped these except their big brother which will be on this list somwhere. These Accuton drivers are insane. I think he has at least $7k, at LEAST, worth of drivers and crossover components in each of these.
Do expensive drivers sound better? In this case, YES YES YES, they ******* do. I had to shake this man's hand. Can't stop gushing over these.
Alright, we need to chat about these domes. This dome was, BY FAR, the best mid at the entire show. Everything else pales in comparison to these. I asked him if I could buy a set of the mids and he said I could. I just have to call Playback Distribution and ask for a replacement pair. I will be buying a set. Maybe we can get a group buy together? I'm telling you, you haven't heard ANYTHING like this before. These are like sorcery. I will be making a second post where I try to buy these. This is a game changing driver.
As a speaker in totallity these were AWESOME. They are small, but they blow out of the water almost everything else at the show. Another one where the engineer was in the room. I spoke with him 3 times today. Kept coming back.
These were ok. Harsh upper mid. Tweeter were good but they ran them too low. A lot of expensive stuff to sound like garbage. Crazy.
26" dual opposed woofer. It shakes the building. Sounds no different from my coffee table subwoofer in my office. This doesn't hit as low as my coffee table. Impressive...... if you don't have a coffee table that hits to 11 hz.
Tannoy
You like jazz? These are for you. Grainy, poor imaging, you are hyper aware that the sound is coming from the speaker. No low end dynamics. Great for trumpets and a saxophone. Pretty sure they were made for that.
My first taste of open baffle. My buddy liked them. I did not. Sounds all washed out. Someone moved a table and the guy had to jump on the dsp to correct the room again. Not for me. Zero bass
More open baffle. More of the same, washed out and not defined. These had bass because of the horn. That was even a little washed out.
Harsh upper mid. Looks cool, doesn't sound very good.
PS Audio
These are some of the best at the show. If you can tame a mid planar, nothing really compares for silky smooth vocals. Paul did it right. I have half a mind to use a planar mid for every mid I do even though I just gushed over those mid domes.
I have answers.
The Short of it:
For those of you who do not want to read this entire write up I will be kind and put my summary up top in a bullet list. There was 3 of us who went. One musician, one loudspeaker builder, and one wife who only ever listens to the system the former two have and doesn't know how any of it works. We listened to 60 systems in one day. Back to back to back. We then came home and listened to my systems.
The BAD
- Most of them do not sound good
- Most of them have a roughness to the upper mids that just sounds terrible. They use these great drivers but drive them straight into their cone resonances. This was the #1 thing we all found wrong with about 80% of the systems
- I swear they pick their crossover points at random. Their crossover networks are pretty goofy
- A lot of them have phase issues. You stand up and it just sucks. You move to the left and it sucks. You have to sit directly center
- Some of them were amazing. These were generally ones where the loudspeaker designer was right there in the room and you could ask him questions. I will get to these units in a bit
- Anything with DSP had a roughness to it. Every single one of us, by the 3rd floor, could walk into a room blind folded and tell you if it was a DSP system or a passive system. Passive ALWAYS sounded better. We listened to about 60 systems back to back throughout the course of a day. DSP to the 3 of us = no good. Was not really subjective. It was objective.
- A lot of them beam really badly. The ones that don't, have a harsh upper mid range
- Do more expensive drivers sound better? Yes, if you use them properly. Saw some $400 drivers implemented horrendously and some implemented properly. And everything inbetween. But mostly the former.
The good
- A couple of systems were just incredible. All of these except two had the loudspeaker designer in the room.
- The better systems used either bespoke of expensive drivers.
- There were a couple mid tier systems that sounded really good.
Lets go through one by one now (I am not going to include most of the bad ones. They sounded so bad I had to just get out of there. If it isn't listed below here and it was at the show, it sounded like crap):
This 4 way was great. It had dynamics and a lightness. Lows were washed out but it was still good
This was ATC. I hear people praise their old mid dome here so I checked them out.
This two way was horrendous. One of the worst speakers at the show. The driver on the table is what they were showing off. Do not buy this thing. It was sticky, like someone covered it in honey. I would guess in your house it'd be covered in dust within a couple weeks. Bad, just all bad.
Morel
These were great. The mid is the one up top and is ported. The woofers down below are also ported. These were REALLY good. I spoke with the engineer about how they don't measure or simulate well. He explained their motor design in detail. It will not simulate right because their design is so different. They have special software they have to use for their motor designs. The price point of morels now looks very attractive to me.
This one wasn't playing. I just thought it was a fun design with the dual AMTs in front of the woofer
MTM Illuminator design. What's not to like? Horrendous upper mid range. So sharp and attacking. Not good. Lows were good, not very dynamic. No idea what they cost but its too much. Feel like the designer dropped the ball here.
I will now never build a line array. This thing just sounded odd. Like a blade of people singing on the left and then a blade of instruments on the right. It was all washed out vertically. Hard to explain. Not a fan. None of us liked this, all of us thought it was just strange sounding. And not strange in a good way.
Full range driver build by Songer. Second best sounding full rang behind a Voight pipe Alpair 11 build. This thing was great. Good dynamics, good upper mid range, very nuetral, good dyanmics. It had it all. It is a giant full range so it beamed like crazy. Move your head left or right and the tone changes. But still very good.
I think these are called frugal horns? Big woofer and a compression driver. Engineer was in the room. Not my cup of tea but the BEST compression driver I have ever heard. He crosses these to the woofer at 700 hz. Pretty impressive and fluid, natural sound out of these. The big woofer lacked dynamics to say the least.
Triangle Art
These were bad. Like just plain bad. Maybe they would sound good if you were 60 feet back in a big room? Crazy directional. Everything sounded muddy. All looks, no beauty.
AudioVideo Artistry
******* AMAZING. What do the Accuton driver's sound like? ******* AWESOME. End game design right here. Nothing topped these except their big brother which will be on this list somwhere. These Accuton drivers are insane. I think he has at least $7k, at LEAST, worth of drivers and crossover components in each of these.
Do expensive drivers sound better? In this case, YES YES YES, they ******* do. I had to shake this man's hand. Can't stop gushing over these.
Alright, we need to chat about these domes. This dome was, BY FAR, the best mid at the entire show. Everything else pales in comparison to these. I asked him if I could buy a set of the mids and he said I could. I just have to call Playback Distribution and ask for a replacement pair. I will be buying a set. Maybe we can get a group buy together? I'm telling you, you haven't heard ANYTHING like this before. These are like sorcery. I will be making a second post where I try to buy these. This is a game changing driver.
As a speaker in totallity these were AWESOME. They are small, but they blow out of the water almost everything else at the show. Another one where the engineer was in the room. I spoke with him 3 times today. Kept coming back.
These were ok. Harsh upper mid. Tweeter were good but they ran them too low. A lot of expensive stuff to sound like garbage. Crazy.
26" dual opposed woofer. It shakes the building. Sounds no different from my coffee table subwoofer in my office. This doesn't hit as low as my coffee table. Impressive...... if you don't have a coffee table that hits to 11 hz.
Tannoy
You like jazz? These are for you. Grainy, poor imaging, you are hyper aware that the sound is coming from the speaker. No low end dynamics. Great for trumpets and a saxophone. Pretty sure they were made for that.
My first taste of open baffle. My buddy liked them. I did not. Sounds all washed out. Someone moved a table and the guy had to jump on the dsp to correct the room again. Not for me. Zero bass
More open baffle. More of the same, washed out and not defined. These had bass because of the horn. That was even a little washed out.
Harsh upper mid. Looks cool, doesn't sound very good.
PS Audio
These are some of the best at the show. If you can tame a mid planar, nothing really compares for silky smooth vocals. Paul did it right. I have half a mind to use a planar mid for every mid I do even though I just gushed over those mid domes.