Hi everyone,
after a very long time designing this speaker I wanted to share the concept to get reccomendations from yall.
The concept is a 3 way tower, 1236 x 436 x 384 mm. It's supposed to be a big speaker, about 136 L of air inside, port on the front, tuned to make the sb acoustics sb26sfcl38-4 subwoofer get very low. The sub part will be actively amplified and tweaked with a little dsp i have. For the two way side I designed a small box that stays behind the big front baffle, where the sb15cac30-8 midrange would play from 200/300 hz to the crossover point at 2000 hz with the sb29rdc-c000-4 tweeter. This section would be passively amplified.
It's supposed to be a good sounding budget speaker. The port would be 3d printed and the rest of the material would be mdf. I would use better materials, but my budget is limited.
The crossover image is just a simulation, for now I began the construction of the speaker and I will need to take measurements of each driver to design the crossover for the two ways.

If you have any suggestion or consideration about this project please let me know!

Click this for the scientific paper.

This is the Abstract:
Quark movement is almost by the speed of light. Due to this speed their inertial mass-effect increases profoundly. That inertial effect is an accelerating force. Within the nucleon the force is the strong force. As quarks movements are back and forth movements, called zigzag or oscillating movements, there is movement in opposite directions. So the oppositely acting forces annihilate each other. However the force acting on objects receding from each other is a trifle stronger than that acting on objects approaching each other. This small difference between these forces is a “left over” force and “leaks” out of the nucleon. In previous manuscripts, formulae were presented to calculate these forces. In the present paper the “left over”, “leaking” force is estimated, and this force is gravity.

Hello all avid lurker here. Need some help with a amplifer board from an old panasonic surround system. This is purely for learning purposes as I hate to see perfectly working electronics go to waste. Its a amplifer board that relies on TDA8920bj. I wish to try and use it as a basic amplifer. I'm kinda stuck on how to get a signal to pass threw it to speakers. From what I have researched I need to apply 30v+- for power. Then 18v to the fan circuit as this seems to control the signal from what I have seen in the service manual. Also 5v to the mute circuit to get the chip to go into the right mode. I've done all the above but so far all I've gotten is buzzing out the speakers but no music. Any help would be great as this seems to be a great chance to learn from as I've started to jump down the rabbit hole of audio and circuits. I've attached documentation on the circuit but if anything else is needed I have the service manual. The source signal would be either PC or phone. I'm still a newb so I apologize for bad grammar or understanding. Amp was from a panasonic sa-pt650

Hello

I think my D20400A is tired...

You can send me a pm. I am in France.

Thanks a lot

Julien

All:

Here are my final files for my Citation 2024 amp.
Major changes from last posting are, new power transformer and choke. Simplified the power supply. Supply is quieter and really stable.
Posted are schematics, assembly info, Gerber files and pictures of final unit.
VU meter circuits are optional.
With new power transformer output power is now at 40 watts. If you want more power you will need to increase the output form 18.5 VAC to over 22 volts.

Have fun and enjoy.
Remember, two things: This is a high voltage tube amplifier and two you need a shorting stick to discharge the caps on the power supply for safety.
If you build this please let me know what you think of and and any changes you make.

Lee Mitchell

Hi everyone
I am new to circuit design and I wanted to try to make a condenser microphone by starting with an existing circuit. I came across the Russell Technologies version of the Schoeps circuit.
http://russelltechnologies.co.uk/rt-sm01.html
Circuit: http://russelltechnologies.co.uk/images/rt-sm01.sch.pdf

Now, I already had a jli-2555bxz3-gp capsule and 2N4416 JFET lying around (because of that one YouTube video ofc). So I wanted to change the Schoeps circuit to fit the 2N4416 JFET.
Besides that, I wanted to add 2 LEDs to the circuit that turn on when phantom power is engaged. I wanted those LEDs to fade out quicker when phantom power is turned off.

See my circuit attached.

After simulating this circuit, I tried to make the circuit on a breadboard. The LEDs work, but still no signal from the capsule.
Can any of you see where my mistake is? And the more important question: why?




And here is the circuit with SPICE simulation. I changed a few things to make the SPICE simulation work:
1. Removed the ferrite bead;
2. Changed the capsule + and capsule - for a VSIN generator. (dc=1, ampl=7.94mV, f=1k, ac=1);
3. Removed XLR1 to GND, because not necessary for the simulation;
4. Changed XLR2 and XLR3 for VDC 48V generators.



In case you were wondering: The two LEDs are white LEDs.

Thanks a lot for the help!

- Ricardo

I last repaired one of my 8 track tapes 🙂

I got volume 2 of "1950s rock and roll collection" and the pad was no good so I went out to find a good pad...... I found one and last night I went about fixing it....

When I opened the cartridge the tape came off the spool a little and I thought I lost the tape but I managed to get it wound back on the spool and into the cartridge and she plays fine 🙂

Now to get volume 3 of this amazing set.... Its a 4 record set,3 8 track set (Im not sure how many cassettes or CDs in the set)

I enjoy Erin's Audio Corner on YouTube - and he mentions that a flat measured anechoic response would generally result in a gently (downward) sloping in-room response and that's ideal.

I've been configuring an XRK WAW (B80 variant) with my minidsp. For 'reasons' I'm doing it in-situ in a reasonable size room that is very live so I've got plenty of smoothing on, to get the overall tone.
Aside from LR2 at 300, level matching, and a bit of PEQ on the RS225 to flatten it and kill its breakup, there is some subtle input shaping for BS and a slight forwardness between 400 and 1k. The BS is actually more than I expected and may be slightly overdone, I'm going to experiment.

The result is extremely flat - in room. Off axis in room its rather dull but I guess that's expected from the FR driver - there's no PEQ on the B80 itself, the 400/800 is I think a baffle effect.

Is making it this flat on average a good idea? They sound quite different to what I'm used to, mostly in a good way. If anything, I'd think they are a little dull sounding overall.

I have for sale a Hameg HM203-6 20MHz 'scope. It's in working condition and includes the "CT" option - a basic component test that can be helpful for troubleshooting in-circuit devices. This is an analog scope and makes a good first 'scope. I probably have a basic test lead that I will include.

I'm asking $75 but open to offers. Shipping probably about 20 - 25 dollars in the US.

Edit Nov 5, 2022: nice analysis and summary of DML materials and response with python script by @homeswinghome

https://www.diyaudio.com/community/...s-as-a-full-range-speaker.272576/post-7159983

Edit oct 27, 2021: a nice Google drive library of DML publications by vdljev:

DML - Google Drive

Edit April 1, 2020: nice summary of DML patents by Burntcoil

A Study of DML's as a Full Range Speaker

Edit Aug 12, 2019: Nice summary here by BurntCoil on how to maximize performance.



I had some cheap exciters that I got from PE a while back and tested them out a while ago with a full 20x30in FC panel here:

Foam Core Board Speaker Enclosures? - Page 225 - diyAudio

I found that a large 20in x 30in panel can sound quite good with nice bass extension and a snappy transient response:



Impedance:



Frequency Response & Harmonic Distortion:



Impulse Response:



The results were interesting in that it sounded nice - with surprising bass and good midrange. I thought nothing more about it until recently prodded by the master of DML, CLS. He has worked on this extensively and is a treasure trove of good info. I since have discovered that you can really do some cool things with them by playing with driver placement, cutouts, adding mass, adding felt, adding ribs, making them huge, making them multi-way FAST, etc. the options seemed almost limitless. Take for example, a large center channel and a super 40Hz capable multiway that CLS built here: PIEZO NXT type panel - Page 60 - diyAudio and PIEZO NXT type panel - Page 61 - diyAudio

I feel like this technology just isn't getting enough attention. There are several very large threads on this on the web. It might be tough for a newbie to comb through. I am a newbie at this so thought I would document my journey for the Full Range forum to follow. I think it really could be a great full range speaker with some careful experiments. This will be really useful with some modeling using CAD and FEA modal analysis - such as available in many CAD packages like SolidWorks. One can play with shapes, cutouts, mass loading, variation in thickness and materials, boundary clamping conditions, etc. The idea is to spread the modes evenly with not any one mode dominating and causing a spike.

First thing is to play with it to get a feel of what we are dealing with. What is nice is that it is relatively cheap to play with. Exciters cost $3 to $20 ea and can be made by removing or cutting out large holes in the cone from an old driver and leaving the spider and VC to attach to the panel. Foam core or corrugated cardboard doped with shellac or PVA seems to be the materials of choice.

Some interesting facts:

1. Although it has no baffle, it is not an open baffle (OB) dipole in behavior - that is, there is no huge bass rolloff and it hits surprisingly low (40 to 50Hz is easy) for a zero baffle driver.

2. It is not a dipole but behaves more like a bipole or an omni.

3. It has very quick snappy transient response - nice drum sounds.

4. It is sensitive to how you mount it or frame it or hold it.

5. You are building a driver in reality - a driver and zero enclosure.

6. You want to avoid symmetric shapes and symmetric exciter placement in order to reduce the effects of the main symmetric transverse drum head eignmodes. Think reflection anti-symmetric shapes like uneven trapezoids, pentagons, blobs, etc.

7. It operates more by having high velocities and large areas for good efficiency vs large displacements - thus small drivers and large panels can be surprisingly loud.

8. The impedance is essentially "flat" relative to normal drivers in that there are modal peaks (many of them) but they range from nominal Re value (say 6 ohms to maybe 8 or 9 ohms throughout the 40Hz to 20kHz range - this presents a very flat load to an amplifier.

Here is a photo of a basic panel I was testing (right before I cut off some edges to form a trapezoid) - panels is about 1 square ft in size and made of standard dollar store foam core board. I suspended it with two pieces of twine from the top corners between a ladder to reduce the effects of edge boundary clamping:



Then I started to play with mass loading by adding blobs of modeling clay (8, 5, 4, 2, 1, 0) so you can see the effect on the resonance modes and the harmonic distortion. What is neat with this test is you can do it live while playing music and immediately hear what sounds more pleasing to the ear. Note the 50Hz bass extension. It is also surprisingly efficient with 85dB and a puny little voice coil. These are 0.5m and 0.71v for equivalent SPL at 2.83v and 1m.

Frequency Response and Harmonic Distortion for...

No added mass:



8 pieces of added mass:



5 pieces of added mass:



4 pieces of added mass:



2 pieces of added mass:



1 piece of added mass:



Impulse Response of 1 piece of added mass, note the sharp transient capability with relatively low after pulse or ringing:



I liked the sound of the 5 and 1 mass the best and for a FAST with a 200Hz XO, the 5 mass might actually do fairly well. Of course, sound clips to follow once I have more time to work on this. Just to demonstrate how quick and easy this is, I did all these experiments in less than an hour including making the DML.

A thread for discussion on all purifi driver builds.

A place to brainstorm and speculate on drivers and potential speaker builds for arguably, objectively, the best no-nonsense engineering-first traditional speaker drivers' money can buy - If you have a complete project underway, please start your own thread and post a link to it in here. Otherwise posting occasional random progress pics and info here is fine but we will keep full build discussion elsewhere.

We are also pleased to have @lrisbo of purifi occasionally check in and post here of which is much appreciated.

A tweeter is on the way 🤓

Updated 26/01/23: Added more build links and intro - (I may stop updating commercial builds moving forward as they are now coming in thick and fast)
Updated 16/06/22: Added builds and review links, updates to builds
Update 17/03/22: below

Time for a bit of consolidation due to this thread getting some hits, and purifi has now released quite a few scrunchy woofers

Links to known projects & commercial speakers using the Purifi drivers (please PM me if I need to add any)

Of course - www.purifi-audio.com , and the team behind the drivers here


Full DIY:

DIYA user @spresto9 has come up with these beauties with the 8" purifi woofer like to details and more pics HERE




Check out this 4" pocket rocket proof of concept build from the Purifi team - all the info you need to DIY!

Spk8 appnote download (.pdf)



@lrisbo Proof of concept Purifi SPK4 (superseded) - Passive stand-mount



@lrisbo Proof of concept Purifi SPK5 - Passive stand-mount - I believe these were at some point being made and sold commercially but have since been discontinued - there may be some floating around second hand market see here Celuaris SPK5 review ASR



@xrk971 PTT6.5/RS28F Waveguide Harsch XO - Passive stand-mount later evolved into a nice Stand mount and Floor standing Transmission Line



@Joe Rasmussen Somewhat Legendary 'Elsinore' - Has been given an (expensive) purifi remodeling. Wow. Skip ahead to post #4,746 for the juicy bits.




Rick Sykora and team's Directiva - Active stand-mount with excellent (objective) reviews, requires external amplification for each driver and an external DSP crossover.





@xrk971 's Raal 70-20xr and PTT6.5 - this one the tweeter is not readily available to DIYers but there may be ways to get it if you're crafty.

(sorry X, couldnt find a finished pic, and I'm out of attachments for this post)


User tktran303's Collection of DIY designs here looking great




Some mindfood for the 8" - a concept by Purifi.



Paul Carmody's Virage - a full design, light on measurements but a fairly reputable designer.



.....and many more concepts within this thread, start reading. Most not fully documented or taken to finished stage though I suspect a few people are still perfecting their builds before showing them off. Remember you can drop people a friendly private message asking about how their progress is going.





DIY-Kits/Semi Commercial:


Yevgeniy’s PuriWave - 2-way stand mount with dual purifi passive radiators



Troels Gravesen Purifi 6661 - Semi-passive/Active plate amplified floor-stander



Troels Gravesen Purifi 6R - Passive bookshelf




Troels Gravesen Purifi Be - Looks like a revision to the above due to ribbon tweeter supply issues.




hificompass Puri Bliss BeWg - Passive bookshelf - I believe the plans are/were for sale.



Joseph Crowe's 1198 - I believe you have to get in touch via the webpage - floor-stand transmission line








Full Commercial:

March Audio Sointuva - arguably where "the bar has been set" for the Purifi 6.5 in a bookshelf chassis.



Jones Scanlon Baby Reds - self powered studio mixing monitors.



The Late Rick Craig's Selah Audio Purezza - A nice stand mount ribbon tweeter design, was available commercially but afaik discontinued, check SH market



Jachim Gerhard Surveyor's - stand-mounts , I believe there is/was a floor-stander made too



Dennis Murphy & Jim Salk's BePure2 - Floor stander - The legends behind the philharmonic BMR and BMR tower



and um, what ever this might be! https://www.audiocircle.com/index.php?topic=175599.0 - probably just a concept, I didn't read the thread. Likely Unobtanium tweeters and probably bottomless pockets required, if it is sold commercially.

Correction - the above was a concept which later evolved to the BePure2 - see this thread at AVSForums Post #10,174
https://www.avsforum.com/threads/th...rs-and-discussion-thread.939744/post-61186397


Further Build links:

Thrax Siren - a 2-way standmount

Jern 35 - 2 way standmount

Buchardt A500 Signature - Active 2 way standmount

WVL Serendipity - 2 way standmount

Taipuu Kero L active with FourAudio PPA-1000 dsp amps. - Not sure if available yet

Salk Sound BePure3 ... Holy **** I need to hear these.



Links to independent driver reviews:

https://www.erinsaudiocorner.com/driveunits/purifi_4/
https://www.erinsaudiocorner.com/driveunits/purifi_ptt65w04/
https://www.erinsaudiocorner.com/driveunits/purifi_ptt80x04-nab-02/ - the eight inch aluminum mid-woofer
https://www.erinsaudiocorner.com/driveunits/purifi_ptt6.5x04-naa-08/ - the 6.5 inch aluminum mid-woofer
https://www.erinsaudiocorner.com/driveunits/purifi_ptt6.5m-08-nfa-01a/ - the 6.5 inch dedicated midrange

Also - please consider visiting Erins Youtube Channel and subscribing! - a much needed light in the dark world of audio subjectivism.

https://audioxpress.com/article/tes...udio-6-5-midbass-transducer-from-purifi-audio

https://hificompass.com/en/reviews/purifi-audio-ptt65w04-01a-midwoofer
https://hificompass.com/en/reviews/purifi-audio-ptt40w04-01a-midwoofer
https://hificompass.com/en/reviews/purifi-ptt65w08-01b-ptt65x08-nfa-01
https://hificompass.com/en/reviews/purifi-ptt65m08-nfa-01a-65-true-midrange

http://www.troelsgravesen.dk/Purifi.htm


Original Post 02/04/2020:

With the group buys well underway the idea was bought up that a design thread be started to discuss build options.

Mine have arrived but I have no build materials and will not be able to get any until we come out of quarantine in (hopefully) three weeks time. I planned to start with a hybrid of purifi's SPK4/5 builds using the same AMT tweeter but maybe using a slot port with the 2.5khz crossover. That and I haven't done any AMT builds so it seemed like a good place to start.

I read of a guy in Aus planning on doing a line of passive and active speakers with the woofer so be interesting if he could chime in here.

So with no materials for the next at least 3 weeks, what better time to discuss build options! Fire away

Since these were on sale at Madisound and I’ve always wanted to try em, I grabbed a pair. I put them in .5 cuft sealed test boxes in the studio with a 100hz hp filter to let em break in a little for a day and then sat and listened to just them in the nearfield………all I can say is simply stunning!!!!!!. There is timbre and clarity that should not be for $50…….I’ve got Revelators that don’t sound as good as these. I’ll follow up with measurements in the coming weeks.

https://www.madisoundspeakerstore.com/hi-vi-woofers-6-7/hi-vi-l6-4r-6-woven-kevlar-cone-4-ohm/.

Approx 400-1000hz sounds exceptionally clear to me……vocals are scary good.

I’ve had this unit 2nd hand for a couple years now and I finally set it back up on my current system and I realize I do not need it.

I had a lot of room treatment done and I have 3 way speakers with a crossover built in and no subs. Using Dirac with an EQ on did not make much of a difference to justify keeping it. But someone with a 5.2 system or full range speakers with no crossovers might get more use.

Make me an offer or I’ll trade it for a quality dac, diy parts, or kits. I paid $800 when I got it from the original owner without a mic or remote.

It includes a remote and the UM1k mic. Couple small scratches on the faceplate top but otherwise good condition. Firmware was updated already.

Shipping from Houston.

Hello 🙋‍♀️


I recently purchased an ADAU1467 development board from AliExpress:
https://de.aliexpress.com/item/1005007868071771.html
(Color: "1467 Development")


Unfortunately, the board came without any documentation, and the seller has not responded to my requests for datasheets or configuration help.


So far, I’ve managed to program the ADAU1467 itself, but I’m facing several issues:

• I tried accessing the EEPROM using various configurations and I²C addresses – without success.
• I also tried setting up the ADC and DAC with all possible pin-configurable I²C addresses – again, no response.
• At the moment, I can’t even control the gain on the ADC/DAC, which makes the board a rather expensive blinky toy. 🙇‍♀️

I'd really appreciate any guidance, documentation, or example projects that could help me get the basic setup working.


Thanks in advance!
Leela

Hi everybody!
I´m attaching a graph of the frequency response of the SEAS CA15RLY woofer under other graph produced by the Jeff Bagby's spreadsheet to evaluate the step that happen by the change from 4 pi to 2 pi radiation when mounted in a 7 L test box, as indicated in the woofer's specification sheet.
I hope overimposed graphs are not a mess, but clearly enough to see the similarity of both plots. Unfortunately, the frequency log scales aren't exactly the same in them.
At the right side of the graphs are the dimensions of the test boxes, also published by SEAS. I used those of the 7 L box for the calculation of the step in the Jeff's spreadsheet.
I would like to read your opinions. I think this is important when designing the crossover because the levels of the pass bands should be at the same height.
Cheers!

People keep talking too much about jitter issues, but did less to make some kind of improvement. I decided trying to do something real – a working asynchronous I2S FIFO.

Before I go any further, I need to make something clear in advance:

1. FIFO is widely believed as one of the final methods to deal with jitter problems. But the asynchronous FIFO itself is just a technology which could provide a logic function to isolate the two clock domain. That means, for an I2S stream, digital audio data could pass through without any modification but the input clock was blocked and replaced with the new one. The new clock is totally independent from the old one except they should have the similar frequency. The FIFO logic itself does not influence the sound quality;

2. What really makes it sound better (or even worse) is the low jitter secondary clock. For example, if we have a new clock after the FIFO which comes with one digit ps jitter(RMS), we should get much better sound quality than before (the jitter level of the master clock from DIR chip usually around 50ps(RMS) level above corner frequency). So, we should pay more attention on the secondary clock and related interface. Everything connected to secondary clock has to be very carefully to deal with; otherwise new additive jitter will be introduced;

3. The size of the FIFO memory should big enough to meet overflow or empty time caused by the worst case of i2s input clock, but still has to be carefully selected to get the balance between the delay time caused by the working depth(usually half full) of the FIFO;

4. FIFO with low jitter secondary clock could only reduce the play back jitter for an audio DAC, but has nothing to do with the sampling jitter. I don’t have any idea if a CD was reordered with poor clock of the ADC.


The main logic functions could be achieved by a FPGA/CPLD chip together with a megabit SRAM. But the clock section has to use specialized clock/timing circuit, because the jitter performance of the output of FPGA/CPLD are far from what we want.

Below is the possible block diagram of this I2S FIFO project:
https://github.com/iancanada/DocumentDownload
https://twitter.com/iancanadaTT

FifoPi Q7 Jan.12,2023 update https://github.com/iancanada/DocumentDownload/blob/master/FifoPi/FifoPiQ7/FifoPiQ7Manual.pdf
FifoPiQ7_0 by Ian, on Flickr

I've searched threads here on the forum but can't find any answers to what my problems are and I lives in Sweden and main voltage is 230V.

Now it is that I finally got my ST-35 up and running, but not without problems, even though this is the third ST 35 and a number of ST 70s behind me, it hums steadily at 50 Hz (I would think) but without finding the reason. I has also built couple others tube and ss amplifier and pre amps.

I have tried all possible troubleshooting, also checked online for something similar and as usual there are different variants of solutions.

When I got home (flea find) with the amplifier, I disassembled it for repair and found an error that the previous owner had made when they built it, the error is that one of the cables to one 115V winding that is connected to the 240V version was pinched under mains transformer there was also a burn mark in the chassis, I then tested the mains transformer and it was correct with all the correct voltages and current.

This I have done, the power supply is handled by an EFB by D.Gillespie new home-etched pc13 circuit board all resistors are original or replaced till others from Allen-Bradley. The tubes are original 7247 and new Russian EL84

But when I start it there is a hum that gets louder when the tubes warmes up, when I remove 7247 it is quiet I have gone through the wiring diagram a number of times but I think it looks right no cold solder I have been detected nothing. All tubes are glowing so that's not the fault (I think) maybe the 7247 are the fault. I have non tube tester but a friend have but he lives i a other part of Sweden.

From my search online there could be two faults but one involves other transformers with 4-8 ohm tap but mine are original and it was feedback the other talked about, that 7247 were broken now I don't know if they are broken I have none opportunity to try right now but I'm wondering if the pinched cable might have caused them to be broken. The hum or oscillates on both channels, possibly a little more on one channel.

I hope someone has a good idea how I should go about it, because right now I'm just have no clue about the problem.

Cheers Anders

Curious if anyone has experience with or measurements of the Audax TW025A28 or TW025A20? The gold one sounds like it simply a gold plated titanium version of the regular titanium, but the response plots are quite different. And they look different measurement systems at different times, so I'm wondering if that is why they are so different?

I dread starting a capacitor discussion as much as anyone, but I've been looking at datasheets on various brands and types of capacitors to use for the +/- power rails on a SS power amplifier. I work mostly on tube amps, so I have years of experience knowing which type and brand to use for a given application. With SS rail caps, I'm not as sure which way to go.

For example, there are the well-known Nichicon Audio Grade lines like LKG and others. But if you look at the datasheet specs by other companies, you see that in recent years, they have managed to bring ESR down in some cases to half that of the Nichicon Audio Grade capacitors and have increased ripple current figures. Companies like TDK/Epcos and United Chemi-con seem to be leading in this area.

Reading sites like the Elliot Sound Projects pages, there's an emphasis on low ESR for SS power supplies, and I've seen some techs using arrays of smaller capacitors to replace single larger capacitors to lower ESR by putting them in parallel. In other words, I see emphasis on this parameter from multiple sources.

On the other hand, Nichicon specifically markets several lines of capacitors specifically for audio, and I've used several of them with good results in signal path applications like KZ and ES Muse types. For the most part, however, other companies simply don't market their capacitors in this way for specific applications. (Elna comes to mind as another company that does, but they are mainly for signal path.) Nichicon doesn't state exactly what it is about their audio grade capacitors that makes them better for audio.

Making comparisons even more difficult, you have to do a pretty deep dive into the datasheets to compare apples to apples since the various companies don't all report their specs in the same way. Math is involved.

So if I'm looking for a 3300uF capacitor, I could go with a Nichicon LKG "Type II" with 120mΩ ESR. But there is also a Vishay/BC Components capacitor from the MAL2056 series listed as having 67mΩ ESR @ 100Hz and 40mΩ at 10kHz. It's also listed as a 12,000 hour part compared to 1,000 for the Nichicon. Ripple current is about the same as Nichicon, but for a longer life.

Then there's a TDK/Epcos cap from the B41505 series that claims 56mΩ ESR @ 100Hz and 55mΩ ESR @ 10kHz. It also claims around 60% greater ripple current than Nichicon or BC Components and a life of 5,000 hours @ 105C, 12,000 hours @ 85C, and 25,000 hours @ 40C. Looks like this line has been around since 2016.

On paper, it looks like the TDK capacitor would win the specifications contest, but does that lead to better sonic performance specifically for a power supply rail capacitor? Would Nichicon's audio grade sound better even though Nichicon is pretty vague on why that would be the case? Or is it simply the case that Nichicon pursues the audio market in a way their competitors do not? I've used Panasonic and Chemi-con capacitors in some power supplies in the past, as well as Nichicon, but I can't claim one sounded better than the other. They were all very good. And is that the answer? Has performance of all modern electrolytics by top companies gotten so good that it's just splitting hairs as to which is "best"?

Hi everybody!
In December 2013, John Caldwell. applications engineer of Texas Instruments Precision Analog, published an interesting design of an active two-way active crossover with woofer baffle step compensation, time alignment and tweeter level correction, You can download such report from:
https://www.ti.com/lit/ug/tidu035/tidu035.pdf
Unfortunately, the Dayton Audio RS28F-4 tweeter is not longer available.
Then, I decided substitute it with the RST28F-4 tweeter also from Dayton Audio, but with some changes in the High-pass filter to tail the new tweeter's parameters.
With the valuable help of Vituix, I found the new configuration that I want share to everyone interested in this project.
For simplicity I jumped the bafle step compensation and the all-pass filter for time alignment. My interest was on the High-pass filter for the new tweeter.
In Mexico is not easy to get the drivers and I have not brought the project to the real world, but my hope is that someone do it and let us know his/her comments.
Kind Regards.

I'm sure a few of you have mixed feelings about the ugly front multi-piece gaskets on most pro audio woofers. They don't always look that inspiring compared to other higher end hifi drivers when mounted from the front, especially when the gaskets are mounted sloppy from the factory. As some of you guys already know, I really like the performance of Eminence Kappalite and Deltalite woofers, but the front gaskets leave alot to be desired in terms of looks.

I came up with a simple, cheap method of improving the look of these drivers by removing the existing chip gaskets and using bulk foam neoprene strips instead. It takes a little skill to get the gasket material started, but otherwise its not that difficult. I used a 5/16 paper hole puncher with adjustable stop to make the holes evenly spaced.

Back in 2020 I had the right front tube of my amp red plate.

I did the following after the Red Plate incident:

• replaced all octal sockets with ceramic ones that have a much more positive hold on the tube.
• replaced the two 6550we tubes used on the right channel
• replaced the rectifier tube
• replaced the 10w bias resistors on all tubes
• rewired and gave extra attention to the quality of the solder joints

Unrelated issue and upgrade:
In the past couple months (April/May 2025) I had an issue where the amp blew the 5amp fast blow fuse on the variac I use to ensure proper voltage reaches the amp. The variac has been in use for more than 5 years and I've had ZERO issues like this before.

I opened up the amp and so no obvious damage. I pulled the tubes and ran through the power up test procedure outlined in the build manual, everything tested fine. I wrote it off and some soft of fluke.

Put the amp back in service and it was fine for about 10 hours of use then, again, blew a fuse shortly after startup.

A few people suggested it could be a bad rectifier or quad cap. Instead of just replacing those two items I purchased and installed the Dual Rectifier option from VTA. Put the amp back in service and listened for about an hour then shut down.

Second red plate:
I had just tested the amp with the new dual rectifier a few hours earlier.
A few hours later I powered it back on and within 10-15 minutes the right front tube had Red Plate.

I was in another room when this happened so it lasted about 30-45 seconds before was able to power off.


This is my second red plate incident and both times it was the same physical location and most of the obvious causes - loose tube socket, cold joint, bias resistor - have been replaced as outline above. I cannot imagine I was just unlucky and had two faulty tubes that just happened to be in the right front tube socket.

This time I am going scorched earth and replacing the following items
- 10ohm 2w bias resistors on all tubes one was damaged during this red plate incident
- 1k ohm 1w grid resistors on all tubes if I am in there, what would it hurt?
- 100 ohm 1w resistors used for the Pentode/Triode switches, 4 resistors total One was damaged during this red plate incident
- DPDT switch used on the right side of the amp (pentode/triode switch) I replaced the left side switch when I relocated them for the DR Board install, replace the right side when installing all new stuff
- the two LM334 regulators
- Replace the four Russian coupling caps with Munorf EVO Oil .22uf I recall reading a bad coupling cap can be to blame, maybe I am wrong.

What other items should I investigate prior to installing these items and putting it back in service?
Thank you for taking the time to read this.

A visual guide to the Rothacher/Pass Zenductor 2

The Zenductor 2 is a mono block, single-ended, zero-feedback, Class-A audio amplifier. You need two for stereo.


Nelson’s article can be found here - https://www.diyaudio.com/community/threads/burning-amp-2024.414636/post-7820909

All photos in this guide will show one amplifier being built.



Parts for one amplifier.

Let's look a little closer at al the various bits -



The circuit board everything attaches to.



Zenductor 2 is powered by a 16v 4.5A brick-style Power Supply.



Here's the magic... the big device is the choke (inductor) that loads the output stage. The darling little transformer is used for voltage gain.



Please note the little circular notch in the plastic closest to the camera, this denotes pin 1.



L to R, RCA input jack, DC power connector, power switch



Capacitors. there are 2 different values that look quite similar. The physically bigger can is 4700uF 25V, the smaller is 6800uF 10V. Make sure you have the right one when stuffing the PCB.



Electrolytic capacitors are polarized. It matters which way they are installed. The long lead is positive (+). The can has negative (-) marked on the heatshrink.
This photo show the 4700uF 25v



1000uF 25v



10uF 35v SILMIC input capacitor.



This is a small value poly capacitor used in the notch network, it's not polarized and can be inserted any way.



Speaker jacks.



Nifty rectangular LED



The input section uses an array of 8 matched Jfet.



Output section is comprised of these two matched Mosfet.



Mosfet heatsinks.



M3 hardware for heatsinks.



Assembly will look like this.

I have an OPA1656 story that may be interesting especially to whomever wants to build the RIAA preamp example in the apps section of the data sheet. I did build that and the slightly modified schemo is attached. I used the attached blank proto board. The Layout is attached. Of the three independent rails on each edge the outside L and R were used for -15V and +15V, resp. The inner two were 0V, center Gnd, branched at power entry at the top. The rails are heavily post-filtered and bypassed and the P/S is external. The DIP8 socket has 0.1uF X7Rs pin 8→gnd, pin 4→gnd and pin4↔pin 8. The enclosure is cast Al/Zn, at 0V and everything “grounded” only via the cable shields to the main preamp. I used polystyrene caps b/c they can be had surplus in 1% values. 000.0mV appears across the 47KΩ non-inverting input load resistors and at rest the finished unit is dead quite.

Now, my turntable is a full-auto linear tracker with internal mute switch used to short the ± moving magnet cartridge coil leads together while lowering onto and lifting off of the record surface. On the maiden voyage of my new external RIAA preamp I turned the system volume down; pressed Play on the TT and once the needle was down, slowly raised the volume to take a listen. Sounded GREAT. Turned-up the volume to let it “burn-in” while I did something else.

Once the side had finished I heard a tremendously loud POP-THUMP (tonearm lifting) and seconds later another very disturbing THUMP-POP (tonearm returned to rest). The mere action of the mute switch shorting and un-shorting the cartridge leads was causing a huge transient at the RIAA output. The 1656 just went berserk! “Somethings wrong and I have to use all my horsepower to fix it right now!”.

Of the op amps in my collection the massive misbehavers are the OPA1656, the LME49990 and the OPA1612. The completely docile op amps are the OPA2604, the OPA627, the OPA2107, the LM4562/LME49720 and the OPA2134. Those are fine.

Long-winded question for anybody is what’s the diff between these two groups of op amps that allows for such infinitely different behaviors in this very, very common circuit? In my case, my TT happens to have a mute function = I’m denied use of the 1656.

I am happy to present you with a project that I did 5 years ago which has served me well since.

---

• The Equalizer for Full Range Speakers Essentials Kit is available in the diyAudio Store.

It does not matter what you are repairing. There are times you "may" want to check transistor DC gain (hFE). One thing that is missing from the discussion is how conditional hFE can be. I am going to take 2SD718-R as an example to setup test while mitigating the condition that must meet minimum requirement. Going by Toshiba, Yamaha, Pioneer, Panasonic and Mitsubishi training from good old days, it goes like this. The first step in testing a device is to obtain a reference data.

Then interpret the test graph to obtain data. In the case of 2SD718 and all high power transistors you know the Base voltage often is given at least 700mV (most are over 1.0V) or higher on schematics diagrams for power amplifiers. Just sticking a device into a test instrument of any kind without satisfying the condition could result a disappointment such as low gain, or unnecessarily noisy.

You might NOT be able to test the device at a collector current of 1A but from the graph you can see that the hFE value reaches closer to minimum of 60 when collector current is 0.01A (10mA) at 25 degree C. You don't want to use a low collector current as you can not be sure of device temperature which is not a room temperature. Since it is a none linear function, scalability is tricky but quick approximation is possible. Leader LTC905 and Tektronix 7CT1N recommend using 0.1mA or 0.2mA for base current for power transistors. You can always increase or decrease base current according to the trace and wave characteristics. See below.

Hi all,

Can anyone suggest a track, as I am running out of ideas searching where is the cause of my old Studer A730's todays issue : as soon as it's powered on, even if lid is open, motor starts spinning backwards at full speed and machine doesn't respond to any order. Swing arm goes full travel outward to disc end, lens tries focusing and laser beam is visible.

Machine fully overhauled 3 years ago (all electrolytics, fresh battery) and it has been playing faultless since. I hadn't used it at all during last 3 or 4 months, but until then it has been working flawlessly.

Some years ago it has been retrofitted by Studer with a CDM-4/16 drive (Neues Laufwerk für A730 Umbaukit MkII 1.630.027.81)

I checked all power supply voltages (+5/-5V, 12V, -15V) and they're all within specifications.

For the time being I'm lost...

Calling all Calgarians!

It seems we have a bit of a diyAudio continent in Cow Town. Notably, @bxt2008, @leadbelly, @kirks, and likely others. In a recent thread I floated the idea of a get-together over a few pints at some point and there seemed to be some interest.

So how about this: We meet at Two Pillars Brewery (910 Centre ST N) at 8pm on Wednesday January 15, 2025. The idea is just to put a face to the user ID and to chat/BS about all things audio.

Please respond below by January 7 if you plan to make it. If it turns out we'll be more than Two Pillars can accommodate I'll find a larger venue that's reasonably central.

Hope to see you at Two Pillars!

Tom

Does anyone know all the different variations of the Russian 6P14P tubes? So far, I've seen suffixes of -K, -ER, -EV, and -EB.

From what I've been able to gather the -EV and -EB are the same. They're the "military rated" version, with double getter posts, thicker mica and glass, higher voltage and vibration specs, and longer rated lifetimes.

I have no idea what the -K and -ER models are. There's also the plain 6P14P, with no suffix at all.

Never mind... I found all the answers here:
http://www.jogis-roehrenbude.de/Russian/russ_roehre_rue_dat.pdf

Hi,I have a stripped Spectral DMA 100 amplifier,need help finding power supply specs for both driver and output.
I have a need to build power supplies as the chassis is missing both transformers……maybe use the chassis,I do have a Diyaudio 5U chassis new in the packing…I have been saving it for a new project,or,if the transformers needed can fit the original chassis,maybe use the Spectral case.
all outputs verified ok.
The boards appear to be prototypes,there is no serial number sticker on the back of the case….found at the Alameda Antique Fair,SanFrancisco in 2017…..
thanks,Dave Grady

By popular demand, here is a new thread devoted to PETTaLS flat panel speaker simulation software, developed by Dr. David Anderson. Flat panel speakers may also be referred to as bending wave speakers, or DML speakers.
Let's use this thread to discuss topics specific to the use of and improvement of this great new tool. Topics could include, but are not limited to:

• new release announcements
• questions about how to use it
• features you'd like to see
• possible bugs
• interpretation of results
• other....

The free version of the software is available here:

PETTaLSFree

Some videos about the software are here:

PETTaLS Videos

Eric

The DIY ACA mini (Amp Camp Amp mini) is in the process of shipping to
the Burning Amp Festival lottery winners and a few of the helpers and
associates.

I am pleased to present the DIY ACA mini article here (in two parts as it
exceeds the size limit of the forum).

There has been at least one addition to the design since BAF, and here's
your chance to look at it again and in more detail.

I am hoping that 6L6 will provide us with one of his usual exemplary build
guides, and I anticipate more general availability of this piece in the
future, as it was intended as a low cost, easily accessed project.



----
See Also:

• ACA Mini Bill of Materials V1.1 (currently used in the ACA Mini completion kit)
• Note about how to bend the trimpot leads in the current batch of completion kits

ELEKIT 2A3/300B SET AMP
Price US$1945.00 (Ll2785C amorphous core OPT)

Stereophile Reveiw : July 2023 Edition ​

https://www.stereophile.com/category/gramophone-dreams​

Stereophile Class A Components​

https://www.stereophile.com/content/recommended-components-fall-2023-edition-integrated-amplifiers




This is our first time to offer Amorphous core OPT. I want to make sure the Lundahl amorphous core is superior than the regular C Core.
This is the sample of Amorphous Core for TU-8900.. Amorphous core requires a longer burn in time..
Is it better??



No Takman for this model - Takman is running out of material to make 2% carbon resistors.

TUBE SET OPTIONS:
COSSOR/Linlai Delux 2A3 + Sylvania 12BH7A $380
COSSOR/Linlai Blackplate 300B +Sylvania 12BH7A $345
COSSOR/Linlai WE300B +Brimar 12AU7 $$695
Western Electric WE300B (5 Years Warranty) + Sylvania 12BH7A


COSSOR/LINLAI Delux metal base 2A3 $285
COSSOR/LINLAI WE2A3 $385
COSSOR/LIMLAI E-2A3 $495
Sylvania 12BH7 $95 (pair)
Brimar 6067/12AU7 $159 (pair)

If you buy TU-8900 with LL2785C and Western Electric 300B, the Cossor/Linlai Delux 2A3 is free

COUPLING CAPS 100nF 450V x 2 (VCAP CuTF $195
Cossor/Linlai WE2A3

46 x Audio Note Tantalum Resistors $5.25 each
4 x Takman 2% (3.3ohm and 8.2 ohm)
2 x AMTRANS 1% AMRG (15 ohm 2W) $9.50 each
2 x Audio Note Silver 0.1 600V $345 each
2 x Acrylic Bracket (to secure the silver caps) Free with Silver Cap









LEFT - TU-8600S (Metal Tube Cover and metal knob), RIGHT - TU-8900 (Plastic Tube Cover, plastic knob) https://www.flickr.com/photos/64593884@N08/ https://www.flickr.com/photos/64593884@ https://www.flickr.com/photos/64593884@N08/


Login to view embedded media https://www.flickr.com/photos/64593884@N08/

Matching headphone impedance/volume levels.

You can change the headphone impedance/volume levels by
simply removing the front panel and change the position of a
short pin.



Directly-heated triode tubes like the 300B and 2A3 enjoy an enduring popularity among audiophiles. The 300B with its rich midrange and extended bass- and 2A3 with its delicate expression and gentle tone offer a very special sonic experience. These 2 tubes are similar in appearance but very different in characteristics and can both be used in TU-8900 without any special changes in amplifier settings. Many manufacturers are producing 300B and 2A3 tubes so users can enjoy trying the various versions available from different vendors. *
*NOTE- TUBES ARE NOT INCLUDED WITH THE TU-8900!



■ Automatic detection of 300B and 2A3 tubes
“300B” and “2A3” tubes look similar but their respective filament voltage and operating parameters are totally different. Their supply voltages need to be adjusted depending on which of these tubes are used in the same amp. In TU-8900, the tubes that are installed are detected automatically and the correct filament voltage and voltage of B-power are automatically set. When 300B tubes are installed- the LEDs on the sides of the volume knob will light up in blue. If 2A3 tubes are installed- the volume knob LEDs will light up in green. Additionally- these LEDs on the right and left side of the volume knob will turn red when there is excessive current due to defective tubes, etc., and the current is shut down to protect the amp. The red LEDs will also diagnose the problematic tube- the right side of the volume knob turns red when excess current occurs in the right channel, and vice versa.




■ Tube-friendly design
Warm-up time for directly-heated tubes and indirectly-heated tubes are different. In most designs, directly-heated tubes warm up faster than indirectly-heated tubes- so often directly heated tubes are often overloaded. With TU-8900, the voltage is gradually raised and reduces the level of overload to the directly-heated tubes.


■ 12BH7A instead of 12AU7
TU-8900 is designed to use 12AU7 as voltage amplifying tubes. However, 12BH7A, with high driving ability, can also be used instead of 12AU7.


■ Ample space for larger coupling capacitors
Coupling capacitors can have a big effect on the sound quality. For the TU-8900, high quality conductive polymer electrolytic caps and polypropylene film caps are provided. However, exchanging for other coupling capacitors is also possible. The maximum size of the caps that can fit in the space is 22mm in diameter x 44mm in length.

■ Matching headphone impedance/volume levels
You can change the headphone impedance/volume levels by simply removing the front panel and change the position of a short pin.


■ Newly designed circuitry
The power transformer has independent windings for the right and left channel to minimize the interference between channels as much as possible. The filament power uses the latest DC-DC converter for extremely low noise and high efficiency. Schottky barrier diodes and fast recovery diodes are used as rectifying diodes that reduces even the most negligible noise spikes. Listeners can enjoy music free from noise even when using a pair of high efficiency headphones. The main circuit of the power unit is unitized per channel as a module.

■Easily change the feedback setting to NON-NFB
Many triode tube amps use negative feedback in their design. The TU-8900 has an option for listeners to hear the triode tube sound without negative feedback. In TU-8900, changing the position of a short plug on the PCB can change the setting to NON-NFB. The gain level increases by approx. 8dB when NON-NFB setting.

■ Updated more reliable tube sockets
After brainstorming with our vendor, we have come up with a more reliable 4-pin sockets for 300B/2A3. Tubes are mounted safely and securely when installed in these sockets.


■ High heat-resistant polycarbonate tube cage
The IEC (International Electrotechnical Commission) sets guidelines on thermal limits on materials and parts, such as a chassis and the tube cage. The TU-8900 tube cage top can heat up to 100 degrees C due to the heat from the output tubes. A robust polycarbonate tube cage with high heat resistance is used to meet the IEC standard.

Specifications of TU-8900

●Stock tubes 　：　300B (or 2A3) x 2pcs, 12AU7 (or 12BH7A) x 2pcs *Tubes not included
* specifications below are with the 300B+12AU7, with NFB, 8Ω loaded
●Rated output ：　8W+8W (300B) / 3.5W+3.5W (2A3) <THD 10％>
●Rated input ：　1Vrms (300B) / 650ｍVrms (2A3)
●Residual noise：　15μV (IHF-A)
●Frequency response： 7Hz-90kHz (with NFB) / 12Hz-45kHz (Without NFB)
●Input impedance ： 50kΩ
●Output impedance ： 4-6.3Ω, 8-16Ω (SW on backside)
●Input terminal ： LINE x 1
●Output terminal ： Speaker output terminals (L/R channel)：Gold-plated screw type terminal (Banana plug usable)
Headphone terminal ：6.3mm headphone jack
●Power voltage ： AC110-120V or AC220-240V 50/60Hz (3P inlet)
●Power consumption： 95W (300B) / 65W (2A3)
●Measurement　： W356xH214xD320mm (including projections)
●Weight ： Approx. 11.4kg (excluding a power cable)
●JAN code : 4952682107941

After 200 hours listening, I am confident to offer the Audio Note upgrade option:​

46 x Audio Note Tantalum Resistors $5.25 each
4 x Takman 2% (3.3ohm and 8.2 ohm)
2 x AMTRANS 1% AMRG (15 ohm 2W) $9.50 each
2 x Audio Note Silver 0.1 600V $345 each
2 x Acrylic Bracket (to secure the silver caps) Free with Silver Cap









Attach files

• Edit silently

The sub I've been using for quiet music I got cheap at Goodwill. It had an amp built in, but a proprietary wireless system, and I didn't know how to bypass it and hard wire the input, so I took it out and ended up replacing it with a huge 3rd order filter I calculated online and assembled, before I knew much about doing things the right way, to force a better response curve that extends much lower than the sub was designed for. It doesn't sound great, but it's not bad, it's just quiet, since most of the work it's been doing is below the tuning frequency, but it's sufficient when there's minimal other noise to compete with.

Anyway, this time around I have Vituix, and I was messing around to see if it's even possible to make a passive filter that can modify the curve without being so affected by the wild impedance curve of a ported sub. I arrived at this solution pictured below, which appears to force a steady impedance curve.

My question is: is this just plain stupid, or will it work? I don't yet have enough capacitors to try it. It looks like a big waste of power, so it may not be that good of an option for a portable speaker, but it should allow for much louder spl by compensating the response curve of an compact undersized low tuned sub.

Maybe there are more practical solutions, but with my limited knowledge I can't see why this isn't a reasonable choice among others. It's just a concept now, and I'll probably try it out if you don't think it's not going to work.

I was able to make a variety of curves, but this one looked clean while keeping the impedance form getting too low. Some would go low even when I didn't expect it to, even after putting an 8 ohm resistor after the capacitor (now between the two), which is how I got started on that path.

The original impedance curve came from a simulated enclosure tuned to 28hz

I recently bought a Pioneer PL-5. I got it hooked up and found that it didn't play speeds properly. I found a couple YouTube videos that addressed this problem. I took the turntable apart. Cleaned it, oiled the motor bearing, cleaned all the switches and pots with contact cleaner so and so forth.

I put everything back together and tried it out. I was able to adjust the 33rpm with the adjustment pot, but I couldn't get the 45prm to adjust at all and runs too slow. The speeds will would skip fast for a second and the back to normal and there is an audible noise as well when it happens.

I have a feeling that I will need to recap the circuit board, But I wanted to see if anyone else had any other ideas before I start doing that. Is it even worth the trouble recapping it? This isn't my only turntable and fortunately I didn't pay much for it.

Any input would be great!

Thanks

Hello my name is mahlon evans and im doing research on amplifiers, and im just here looking to get answers to my questions and hopefully do the same for others. im starting to repair amps and hopefully soon build my own using igbt modules from 3phase variable frequency drives.

Anyone have any experience troubleshooting one of these guys?

I picked one up today that is not behaving properly. When plugged in, the amber power light turns white, as expected; lights on front panel blink a few times as expected; then the power light turns red briefly, then goes back to amber.

When holding down the "Bass EQ (SERVICE)" button in the back, which should supposedly put it into service mode for the purposes of re-flashing firmware, instead of the lights on top turning on, the lights on front turn on instead, which is not indicated as expected behavior by the manual or firmware updating instructions.

It's also not obvious how to get the thing open. It appears it's held together with plastic clips, but I can only relieve tension on one of the edges.. I feel like I'm missing something, and likely to break the cover if I proceed.

Hi Guys.
I was planning a speaker project and wondered if anyone could help me with the calculation for a dual-woofer transmission line design.
I can find online calculators for single woofers but not dual, so I'm thinking I need some advice from your expertise 🙂
Many thanks for considering my request.

Hallo,

greetings from a fan of Sansui/Trio products, a little familiar with soldering iron......
Audiokarma / Mike244

Best regards,
Mike

I've got 8 brand new M26-WR09-08 woofers sitting in boxes and wanted to do something fitting with them. These are very good sounding drivers, even by today's standards. I just wanted to get the best use from them in some type of project. I was thinking some sort of large 3 way ala Dunlavy. I also have 2 SS D2905-9500 which have a similar flavor of sound. The M26s have very floppy suspensions which make them more suited to a large sealed box, but Qts is relatively low.

This is a pair of the Manzanita Ultra open baffle DIY version of course
Speakers that were designed by John Busch of Manzanita Solutions
In Texas,he spent a couple years in R&D to get these dialed in,
They use Vifa full range driver and a GRS 15 Woofer
The crossover uses Mills resistors with Sonicap on the Woofer
And a Jupiter VT on the full range driver.
John listed these for $3900 on his site and they do sound fantastic
They fill a room like no other speakers I have built with great depth and imaging.
Baffles are 3/4 Baltic Birch Ply
they are 49.5 in Tall and 25.5 in Wide
$580 local pickup in Huntersville, NC area.

My Prodigy sometimes makes a clicking sound:

MartinLogan Prodigy clicking sound - YouTube

After consulting with ML I replaced the power supply and then the transformer with new replacements and it still didn't completely fix the issue (though it seemed to happen less frequently).

After a few months it largely went away, I may get a few clicks every month or so.

Lately it's starting to happen more frequently again (maybe once a week, and when it happens it does that on and off for minutes).

Any idea what causes that? It's not the panels, those were replaced and I also swapped them between the two speakers and it stayed with the same speaker. Vacuuming didn't help.

thread index at the end of this post!

When planning, simulating, building and measuring bass reflex enclosures for 2-way speakers one difficulty is dealing with port resonances in the midwoofer’s passband.

I thought it should be possible to absorb resonances with Helmholtz resonators in/at the bass reflex port.
Obviously I am not the first to come up with this idea, but I also didn’t find very much about it on the internet.
Thus I decided to make my own measurements, see the following posts!

some web references:​

Short thread about this issue on diyaudio. note that the thread starter wrongly refers to the "1/4 wavelength resonance" of a port. This is not correct! The fundamental resonance of an open tube happens at the frequency that has a wavelength equal double the tube length.

A german thread about port tube resonators.


various web references for resonance of open tubes and helmholtz resonators:

https://en.wikipedia.org/wiki/Helmholtz_resonance

https://en.wikipedia.org/wiki/Acoustic_resonance#Open_at_both_ends

https://www.physicsclassroom.com/class/sound/Lesson-5/Open-End-Air-Columns

https://en.wikipedia.org/wiki/End_correction

http://troelsgravesen.dk/vent_tuning.htm (including end correction values!)

calculating resonance of bass-reflex port (open tube resonance):​

occurs at frequency that has half wavelength equal to end corrected reflex port length and respective frequency multiples.
Oscillation node (pressure maximum) is at center of port (or further divisions for multiples).
pressure absorber works best at the respective node.

Option 1: tube absorber​

Simple tube, one end closed, it should thus have roughly half the length of port for absorbing resonance of port fundamental; can either be parallel (and inside) the port or 90° perpendicularly mounted at port. Open end should be located at half port length.

Option 2: Helmholtz absorber​

Mounted at half bass reflex port length, connected by its own small Helmholtz port to the bass reflex port

-------------------------------------------------------------------------------------------------

Thread index​

#3 - first resonance absorber tests with tube test setup
#5 - decay plots of test bass reflex box
#8 - resonance absorber results by @augerpro
#11 - link to a relating message by @rdf including link to roozen/philips-paper
#19 - new parallel 6th order bandpass test box for further investigations
#22 - dealing with enclosure resonances
#25 - chuffing audibility test
#42 - particle photos (using water sprayer)
#48 - port 2 variants and measurement results
#50 - port stalling test
#54+55 - influence of smoothed port flange
#56 - port 2 impedance results
#58 - port resonance absorber test
#81 - link to bryce doll paper by @Hearinspace
#103 - port 2 variants resulting in the same tuning frequency, with geometry drawing
#104 - photo of port 1 variants
#141 - port wall stiffening influence
#157 - port 1 variants response measurements
#159 - chuffing RTA measurement of straight port 1
#161 - chuffing RTA measurement of rectangular curved wall port and big 3d printed port
#165 - chuffing RTA measurement of flat port and small straight port
#166 - resonance absorber setup
#167 - measurment of resonance absorber lenght variations
#202 - resonance absorber filled with melamine foam
#206 - chuffing RTA measurement of 3d printed port with resonance absorber
#214 - influence of port diameter/dimension for enclosure resonance transmission
#228 - small 3d printed port drawing and measurments
#230 - testing noise of roughened port surface
#236 - port with resonance absorber documentation by @Kwesi
#249 - chuffing RTA measurements in singe dB steps (small 3d printed port)
#251 - separating resonance absorber from the port with latex membrane
#288 - link to salvatti devatier button paper
#302 - explanation of boundary layer thickness by @andy19191
#310 - impedance measurements for port 1 variants at different input levels
#320 - "progressive port geometry" concept
#324 - progressive geometry port measurements
#328 - progressive geometry port length correction
#329 - progressive geometry port impedance measurements at different levels
#330 - progressive geometry port response
#331 - progressive geometry port chuffing RTA measurement at 100 Hz
#341 - output level measurement / comparison
#349 - is airspeed the main chuffing factor? progressive port chuffing RTA measurement at 50 Hz
#350 - new particle photos
#352 - explanation of turbulent air motion by @andy19191
#363 - relating chuffing to particle displacement
#367 - first GIF-excepts of 120 fps particle videos
#390 - port variants with sound recordings by @Tenson
#391 - correct port particle displacement calculation formula by @David McBean
#395 - (1) first slow motion video: hard edge port
#407 - (2) second slow motion video: flared port
#434 - flange variant video
#438 - (3) third slow motion video: progressive geometry port
#448 - influence of air particle displacement for the excitement of low frequency noise
#449 - differences of a big and small (optimized) port for a small 2-way midwoofer
#460 - (4) fourth slow motion video: small straight hard-edge port
#468 - small very flat port - checking for boundary layer flow resistance
#503 - how to calculate the strouhal number using max port air velocity data, CORRECTION see #591
#504 - water tank simulation
#522 - @Dmitrij_S Karlson couple port
#526 - flared port geometry definition
#529 - 2 way speaeker test ports to be measured ...
#531 - ... response measurements ...
#546 - ... chuffing measurements (RTA) ...
#591 - correct calculation of strouhal number, related to peak-displacement instead of p-p- displacement (thanks to by david mc bean)
#595 - how to find a suitable port exit diameter using the Strouhal number (corrected version!)
#616 - first beta version of a simple excel sheet for tuning calculation of NFR=0.5 ports
#621 - relating the strouhal number to compression and distorsion
#624 - parametric fusion 360 model for a NFR=0.5 port by @augerpro
#627 - augerport with resonance absorber by @augerpro
#646 - parametric NFR=0.5 port model for freeCAD, including STEP and STL model
#652 - announcement by @David McBean: stouhal curve included in the port exit air velcity graph.
#654 - how I make my 3d printed ports
#680 - chuffing/noise audibility comparison: straight and flared port
#704 - big collection and evaluation of 3 speaker and 14 port variants - proposed MID PORT STROUHAL NUMBER (MPSN) parameter
#747 - updated excel calculation tool with correction and variable NFR ...
#748 - ... and the imperial version of the same calculator
#753 - comparison ports vs passive radiators
#811 - compressing the optimum geometry definition to two relevant parameters
#812 - The breakthrough: Finding compression behaviour patterns
#847 - Iterative port geometry optimizer tool


(will be updated)

[Update]
For easier navigation, here's a quick index of the posts in this thread:
Post #1 – Introduction & Component Selection
Post #4 – Design Philosophy & Schematic
Post #35 – Simulation Results (Multisim)
Post #40 – Mechanical Build & Assembly Photos
Post #46 – Altium Project + PDF Documentation


Hi everyone,

Just wanted to share the start of a project I’ve recently finished, a passive inverse RIAA filter that ended up being surprisingly useful (and a bit more involved than I expected). It’s designed to help with testing both MM and MC phono preamps, staying accurate across the full audio band: 20 Hz to 20 kHz.

Laser-engraved dual-channel filter enclosure:


The motivation was pretty straightforward. Most IRN filters I came across, whether commercial or DIY, either lacked the precision I needed, didn’t handle MC levels well, or relied on active stages that I wanted to avoid. If you’re building or measuring phono stages, having a clean, analog-domain IRN filter is super helpful, especially when you want to check frequency response or verify your RIAA curve.

The original “The Audio Amateur” article, 1980:


This one’s based on the well-known Lipshitz & Jung design from Audio Amateur (1980), with a few ideas borrowed from more modern builds like the Hifisonix Accurate IRN. But it’s been adapted and rebuilt from scratch with the following goals in mind:

•Dual outputs: –40 dB (MM) and –63 dB (MC)

•Fully passive RC topology, no active gain stages

• ±0.11 dB deviation from ideal RIAA (simulated)

•Separate shielded PCBs for left and right channels

•Premium hand-matched components for better tolerance

Resistors and capacitors were carefully hand-picked to ensure high precision and matched performance between boards:


I’ll go into the schematic and how I structured the attenuation stages for the next post. Even if IRN filters aren’t part of your regular toolkit, I’d love to hear what other folks here are using when testing phono preamps.

Cheers,
Alan

I have two Taramp MD8000.1s and one MD3000.1.
The MD3000.1 is missing IC3, and I would like some help identifying what was there before.

Hi my name is Okamarix!


I am new to audio design and love to meet all ethusiast in this forum to guide me through my journey!
I work for a small audio startup and having the community help me here will translate into possible real life products coming out!
My passion is to design consumer products that would enhance the way we listen to music as we go about with our busy lives!

I'm Just getting into vacuum tubes and amps and learning a LOT. I look forward to reading things and learning from you!
I have a ton of tubes I've collected since December and play every day I can.

Streamer - Pi2D Mercury Streamer v2
DAC - Topping D50III (iFi Power-X)
Preamp - Little Dot III; Little Dot Mk IV (v3) SE - WE408A (AQ NRG-Y3 cord)
Amp - Topping LA90 Discrete (AQ NRG-Y2 cord)
Speakers - B&W DM601 S3
All AudioQuest interconnects

When I was young, we spent hours on end playing what we called word game. Same rules but it was always 4 letter words.
I was introduced recently to this new sensation and tried it today. Now I know it's beginners luck, but first time out I got it in 3 words.
I think I'll try again and let it bring me back to earth.
Who else is doing this?

Hi again to the community. Long time lurker here.
I am a bit tired of my current speakers (ScanSpeak Revelator 18W/8531G-00 + D2905/9700) and want to build something DIY. A tiny three way. Maybe with an added floorstander bass base if the SPL is too low.
And now the twist: The woofer will be MFB controlled. I would like to play a bit more with this technology.

I feel there is a need to have an active thread here about MFB. Moreover it will be better to have 20 opinions on the matter. If I work on the speaker alone it will be only mine. Comments, ideas, remarks - all welcome!

For sale various transformers,

2 x O core 230 V 100 VA 2X 15V James transformer (one potted) 35 Euros each.

1 X R Core 230 V 30VA 1X12V 2,5 A 25 Euros

1 X R Core 230 V 30VA 1X7,5V 4 A 25 Euros

After years of loving my aleph O monoblocks
I've decided to replace the capacitor's .
My question is are there any capacitors that are better than the original and should I up the micro farads any ?

Hello,
Populated PCB. Pearl3 boards and UDP3. Fully tested.
Slightly change:
More choices for R and C load.
More choice for gain.
Only THT components (except 2sk209)
Vishay and Yageo 1% resistors
Panasonic MKP, Wima FPK.
Component come from Mouser, TME and Reichelt.

EU only.



180€ + shipping cost.

Hi, I've a couple of Dayton 2" Full Range CE48-4 and I'd like to make a little boombox enclosure.
I'm aware it wouldn't be an eartshaking result, but I'd like to take the best out of them.

I can't find almost nothing on this speaker and seems nobody had made a project with it.

I tried an online enclosure calculator and it came out with a 0.04 ft3 (1.15 lt) with a 1" by 12" port.

Is it acceptable and correct?

Thank you

Hi guys,
I have one phoenix gold ZX350 with buzzing problem. I have this noise only with gain set to max (0,2V), and source connected. Without source no buzzing/noise. I have tryed different sources, but the problem is still present.
Can be normal this buzzing? For understand, is like high setting level on the guitar amplifiers.

This is the end of "my road" in audio DIY and will offer these gems.... unless I regret
Paired and consecutive serial numbers (hidden here). Very good condition, only a minor damage in the bezel that is not visible once installed. It is marked in red in one picture.

Asking 1500€ + PP fees + Shipping.

BEWARE: before shipping I will take measumerents, videso and T/S data from the units to assure to the buyer that they are in absolutely perfect working condition.
They will be packed absolutely safely adn after agreed with the buyer the shipping, I WON'T TAKE ANY RESPONSIBILITY FROM DAMAGES AT SHIPPING. NO RETURNS ANYWAY.

Looking for 2 or 4 of these woofers, ideally in the UK or Europe.

The Iron Pre is now listed in the diyAudio store for anyone to purchase.

Until the 'Build Guide / Build Thread' is created, this post will contain all current schematics and notes for the Iron Pre sold through the diyAudio store. Check back frequently to ensure you have the latest files.

Sep 14 2023 - Below is what you're waiting for! See some awesome information and help from 6L6 on the SE build. A new thread and the guide using the web interface will be posted ... soon. Post #2291

Background

Hello Happy DIYers / Greedy Boyz!

I am thrilled to announce that Zen Mod's Iron Pre essentials kits will be offered in the DIYAudio store. This is not a group buy. You can learn more about the project in the thread linked below.

https://www.diyaudio.com/community/threads/whats-wrong-with-the-kiss-boy.293169/

Highlights include matched Toshiba JFETs from Nelson Pass and high-nickel CineMag transformers. 6L6 has volunteered to post one of his incredible build guides also.

If you're a Smiths fan, you may ask, How Soon Is Now? They should be available for order before the end of the year. At this time, we have enough parts sourced for 100 SE and 50 balanced kits.

The next obvious question is, how much? Costing is not final yet, but the goal is $100 for the SE kits and $125 for the balanced kits; a tremendous bargain. We have contingencies for all the parts, and we hope that this will be a permanent addition to the store. However, for now, we can only promise what we've got. Get 'em while you can.

Click the link below to see what will be included in the kit, answer a few questions about what you might like to see in the future, and get on the list.

Note - The n-channel JFETs will be 2SK370.

Quick and Dirty Startup Process

This happens after: the boards are stuffed, the AC supply is verified and connected properly, and I/O has been connected. Nothing needs to be shorted. Note the additional step for the V4 SMD version.

1. Set V+ and V-
   
   Adjust P1 and P2 for each board until V+ is +15V0 and V- is -15V0
   
   GND, V+ and V- pads are clearly marked on PCBs.
   Do not move forward if you cannot adjust the voltages to within 0V1 or if the voltage seems unstable.
   
   
2. For V4 SMD Only- Set current through JFETs
   • Set DMM to DCmV.
   • Place probes across R34 and R37 for SE or R40 and 41 for Balanced. You can also use square pads / test points near resistors.
   • Turn P4 and P6 respectively until DMM reads 14mV +- 0.05mV - See schematic.
3. Null DC offset
   • SE
     • No jumper caps in place for JP1 or JP2
     • Measure at center pin of JP1 and JP2 NOT between those two pins*
     • Turn P3 / P4 (V3 and earlier) or P3 / P5 (V4 SMD) respectively until voltage shows 0V +- 5mV
     • Cap the jumpers for your choice of gain.
   • Balanced
     • No jumper caps on JP+ or JP-
     • Measure at pin 1 of JP+ and JP- NOT between those two pins*
     • Turn P3 / P4 (V3 and earlier) or P3 / P5 (V4 SMD) respectively until voltage shows 0V +- 5mV
     • Cap the jumpers.​

Updates

4-May 2023

Edited 7-Aug 2023. All in-line photos have been removed. Please see attached files for all documentation.

5-May 2023

Updated Single-Ended BoM to correct 330R part notations in the gain stage to R28 and R29.

Attached are the Bill of Materials / Parts Lists - Note File Names for Balanced and SE

26 - May 2023

Updated SE and Balanced Bill of Materials to indicate that snubber components should not be installed.

Balanced BoM Filename - BOM_Store_Iron_Pre_Balanced_Dist_v5.pdf
SE BoM Filename - BOM_Store_Iron_Pre_SE_Dist_v5.pdf

27 - May 2023

Updated SE and Balanced Bill of Materials to correct and clearly note which diodes should be installed for input switching.

Balanced BoM Filename - BOM_Store_Iron_Pre_Balanced_Dist_v6.pdf
SE BoM Filename - BOM_Store_Iron_Pre_SE_Dist_v6.pdf

1 - June 2023

Note - No changes required. However, the packing lists some of you will receive may note LM336-5.0. That was a typo; apologies. The correct parts (as supplied and noted in the BoM) are LM336-2.5.

Removed the link to sign up indicating interest in kits. Those currently on the list will get first priority for the next round of kits. After that, they will be sold through the normal process through the store.

6 - June 2023

There are two gorgeous prototype chassis available; one designed specifically for SE, and one for Balanced. You can find some details in post #431. The depth for both chassis is 280mm. There is additional information sprinkled throughout the thread re: acceptable sizes and some potential part numbers for IECs, input / outputs etc. along with pictures of some examples. Please search first before asking chassis questions, and I'd recommend using the latest posts' information. Again, they are prototype chassis, and anything could change at any time until the design is finalized. The best source of information re: the chassis is directly from Modushop until they are sold in the diyAudio store. Timing TBD.

8 - June 2023

Added parts placement and pcb layouts for those interested.

30 - June 2023

V7 - Minor Updates to BoMs. QTY added. Ensure to check quantity per board against the quantity you need for your project. Added links to a popular online website to show examples of parts that will work for the connection between the main boards and the twister boards for input selection / LED power etc. Added generic descriptions for those that would prefer to select their own parts.

1 - July 2023

V8 - Minor Updates to BoMs. Added heatsinks for M3 if 12V relays are used.

7 - Aug 2023

I'm excited to say that more kits will be available very soon for 'round 2'. Continue checking this post (as always) and the thread overall for up to the minute updates.

In his graciousness, ZM has made some minor running changes. Changes are:

• Updated transformer snubber circuit.
• Easier positioning / mounting of the CineMag transformers in some situations.
• Changes to allow easier use of some logic circuits for input switching.

Boards that include the changes will note "2023" vs. "2021" on the silkscreen. The Twister board accompanying the 2023 boards notes V.3. Both 2021 and 2023 boards are included with 'round 2'. You cannot choose which you will receive, and you will not know which you will receive until they arrive. Do not fret if you get a kit with 2021 boards. If you need to use a particular type logic solution, there is a very easy modification previously noted in the thread, and the snubber is not necessary. The changes made were a kindness from ZM, but all 2021 boards can be made to function just like 2023 boards with a few user-tweaks described in the thread.

Note - The attachments have been packaged and note which files to choose for the respective boards. Previous attachments and in-line thumbnails / photos have been removed for clarity. The BoMs have been updated slightly for clarity.

9 - Aug 2023

There is a minor error on the silkscreen for the boards marked Iron Pre SE Zen Mod Labs 2023. The polarity notation for C11 visible when the cap is installed is incorrect. Ignore it.



13 - Aug 2023

His Mightiness created two graphics for how to wire standard pots for both SE and Balanced. Attached.

29 - Aug 2023

Minor updates to balanced BoMs. Removed reference to D15.

31 - Aug 2023

Added wiring diagram for AVC for SE. See post #2113 for context.

21 - June 2024

All testing for the Super Mega Deluxe version is complete. Kits will be back in the store 'soon'.

25 - September 2024

"Soon" is relative. 🙂. SMD kits are on sale. The schematics and files for the Super Mega Deluxe (SMD) have been attached in their appropriately named .zip files. Enjoy your builds.

26 - September 2024

A few people purchased the "completion" kits for the V3 and earlier boards and were wondering if they could be used for the V4 SMD kits. A lot of the parts are identical, but below is what you'll need in addition and to swap a few parts.

For balanced you will need:
4x additional 825R or 820R resistors - I like these Vishay BC 825R
8x 58R or 62R resistors - I like these Vishay BC 62R
4x 1R resistors - I like these Vishay BC 1R
8x 100R trimmers - I like these Bourns 3296 Series 100R Trimmers
4x 1uF film caps with 5mm or 15mm lead spacing - I like these TDK 1.0uF with 15mm Lead Spacing

For SE you will need:
2x additional 825R or 820R resistors - I like these Vishay BC 825R
4x 58R or 62R resistors - I like these Vishay BC 62R
2x 1R resistors - I like these Vishay BC 1R
4x 100R trimmers - I like these Bourns 3296 Series 100R Trimmers
2x 1uF film caps with 5mm or 15mm lead spacing - I like these TDK 1.0uF with 15mm Lead Spacing

27 - September 2024

Some potentially helpful additional parts in post #3784. If people have more helpful suggestions, I can add them.

3 - February 2025

Added diagrams for setting buffer current in V4 builds.

Hello

I'am Elmü from ElmüSoft.
I wrote a lot of useful software for electronics and computer freaks.
You find it on my homepage.
www.netcult.ch/elmue

Hey all,
I'm Ricardo. I am definitely not a newbie to audio, but quite a newbie to electronics. Although this quite interests me.
On this forum I would like to learn more about this. In the near future I wanna join a 1,5 year course to fully understand electronics and use forums like this to apply it to audio gear design.
I wanna implement this knowledge and experience into my playback engineering profession.

Hello everybody,
long time lurker, first time poster. I'm interested in building traditional and class-D power amps, so I think this is the right places to discuss those topics.

Greetings from Italy!

For sale a pair of Audiotechnology 15H52 12 06 SDKM Midranges.
One of the very best midranges you can have.
New. Original packaging.
Asking 420€ + PP fees +Shipping

Hi, joined the fourm as I have recently found myself lurking around old discussions around preamps and analog circuit designs. I'm in the processes of building my own devices and would like feedback on my designs from people much more exprienced than me.

I'm building a Tubelab SSE and just finished drilling out my chassis, but realised the thickness of the aluminum plate means that two of the resistors come in contact with the aluminum plate (see Pic 1). These are the two resistors that are located on the same side as the tube sockets, and are recommended to have a few mm gap (I assume for heat dissipation, see http://tubelab.com/designs/tubelab-sse/manual/resistors/).

Assuming that it's not ideal for them to touch the top plate, I'm wondering the best way to adjust this. The three options I can think of are: (1) drop the PCB lower to create a gap, but this would then lower the tube sockets from the top of the plate, which are currently flush, see Pic 2; (2) resolder the resistors so that they are almost flush with the PCB, but presumable this gap is recommended for a reason, or (3) flip the resistors to the underside of the PCB, which there is room for (Pic 3), but this would put them in close proximity to the big capacitors and the output caps, which I assume is why they are inverted to begin with.

Any suggestions on which solution seems best? Is there something else I'm not thinking of that would work?

Hi Thanks for reading. I need help with an open baffle speaker. I am using a B&W driver in a sealed box to reproduce the low end as I do not have the space for OB bass, xover frequency of 400hz with second order rolloff

The mid is minimalist OB visaton B200 which a lot of people seem to like, and finally a B&W tweeter with a 10khz crossover

The two B&W units sound good but the visaton is beaming and boring to listen to. What driver would you recommend to swap out for the visaton. For every drive unit that holds promise, I then read reports from a ton of haters. Lowthers were reported to be good but then in other posts haters tore the lowthers to pieces

I have tried filters and phase plugs with the visatons but am still not happy

As a new Magnepans 1.7i owner, I’m in the break-in period. Really working that mylar membrane requires power, meaning loud listening. I can tolerate loud music only for a short period. So, I decided to push membranes with a very low frequency signal, where dipole baffle is acoustically in short circuit (+ human hearing is insensitive) and doesn’t produce any sound, even at high power. Using signal generator at 1 to 5 Hz, loudspeakers are pushed with continuous power. I can clearly see mylar membrane excursion.

My question to experienced owners is whether there is anything bad in that method. I’m using only 25 Wrms, but that is 10 times more than I need on average for listening. It should speed up break-in for low frequencies, compared to music listening.

Today I bought 🙂 (pics are not mine)

Harman Kardon Citation 11


Yamaha B-2


Nakamichi 480


Philips CD-104


Yamaha CT-610


Philips CDR-765


CEC DD-8200 with Shure V15 type IV


Grundig Fine Arts T-903 MKII


Next 😀

Oops! Almost forgot yesterdays goodie 🙂

I started a new project to re-home a pair of OPTs from an old Scott 299 amplifier and am looking for PI circuit opinions/ideas. Ultralinear isn't an option with those transformers so I decided to experiment with a really stiff screen supply. It's an all-tube design except for the rectifiers but I'm really impressed with the performance of the regulator and anxious to hear it. I'm going to be using the 6P14P as the output tubes (the Scott 299 used 7189s originally) and it idles right at 500 volts on the anodes. There's lots of room for screen V adjustment within a range that still provides excellent regulation so I'll be doing lot of tinkering.

Anyway, the 299 used an ECF80 phase inverter and I've re-drawn the circuit (attached) but am wondering if anyone else has used this design and how it compares to some of the others. Chassis constraints limit me to a single 9 pin miniature tube so I guess I'm not "married" to the ECF80 if there's something that is a lot better, but I've read a lot of great stuff about the tube and I have a bunch so I planned to at least start out with it. What I don't know though is how the original Scott circuit design might compare sonically to some of the others. Yes, I know, opinions and tastes vary from person to person but having never heard a working Scott 299, I thought I'd ask the guys that play with this stuff more than I do. I've been into lots of guitar amp projects and amateur radio stuff but this is probably my first "hi fi" audio project so in that regard opinions are worthwhile to me.

Enough blabber. PI schematic attached. Many thanks in advance for your opinions, ideas, suggestions etc.

As discussed here I have implemented a good approximation to a 4th order LR to a Seas tweeter by estimating the existing Q and frequency, and using an LT to raise the cut frequency and make the response align to the 2nd order Butterworth - and then overlaying a further second order.

This gives a pleasing result with my miniDSP crossover.

I'd like to use this technique again - but with a conventional (if external) crossover. Is there any software that would do this, or should I just try to replicate the response by simply fiddling in XSim with trial and error? I don't need to introduce any gain, its all attenuation and raising the cut frequency.

(And yes that leaves me with the Z offset to mess up phase, which I deal with in pure delay in DSP - but it will be a starting point, and for some tweeters with very low Fs, I might still look for around 1.2kHz 4th order - like my Wavecors for example - which should reduce the phase error somewhat).

Things I have for sale,

a set of Tannoy CPA 12 speakers: CPA 12 original cabinets, 3134 drivers with original crossover, speakon connectors. Tweeters are brand new, with new ferrofluid; very good functional condition&sound, just a bit tatty cabinets and one sospension could have been applied better, just not impacting on sound&functionality AFAICT, asking 750eur due to new tweeters.

a set of Tannoy 3142 drivers, only drivers, no enclosures, no crossover. Looking/sounding very good except a small imperfection not affecting functionality, tweeters would probably benefit from a cleanup and new ferrofluid, asking 550eur for these.

Ideally to be picked up from this neck of the woods but could be shipped at buyers expenses and risks.

Thank you to Kimmo Saunisto for this wonderfull software😛, very very gratefull.
it is very complete and powerfull, but you need to know well loudspeaker design.
Software

thank you again.

I have around 1000 CDs collected over many years but find myself increasingly using streaming (Spotify and Apple) along with my vinyls. I am moving house, and SWMBO has intimated that they all need to go. What do you think? Keep 'em or ditch 'em?

i just typed that into google - its tells me nothing apart from what they want to sell me - anyone help please

I was looking into buying a couple of transformers and went to their site and it was gone. Are they out of business?

The Singing Bush Tips 'n' Tricks, so even Cheerleader Girlie can build it ...

....OK , here it is

ORIGIN THREAD : The Singing Bush


First few posts with graphical info, then I'll write separate posts for both amps, explaining few details


////////

however , most important thing when starting, applicable for both amps:

be sure that trimpot in buffer negative rail (lower JFet group source) is set to max position, prior to first powering up - check that measuring across parallel 39R resistor - reading must be close to 28R

/////////

another thing - remove that silly blue collar from needle wire terminal you got from me - either use heat gun or heat it with solder or lighter ...... then pull it

all wires need to be crimped then soldered in wire terminals, then heatshrinked, to look nice

///////// ( you can see from these slashes that I spent some time recently struggling with Arduino )

for 2SK77B - lucky bstrdz having these - all 3W resistors in Mu part of amp - they are still 1R/3W , no change ........... Iq 3A2, output node or SIT Drain (what's easier to reach for measurement) set at approx U/2

///////////

edit 27.07.2020. - SIT Singing Bush startup procedure , post #29

Hi everyone!

It's been almost two years since I last built a speaker, and I'm getting the urge again.

[TLDR:
A more compact floorstander using an SB Acoustics SB15SFCR39 for bass in a vented enclosure, extending further down to the early 20hz with boundary/room loading. The B&C 5CXN44 in a sealed enclosure for mid and high.]

My current setup is really good (here), but a few aspects have me considering a change:

Size: The speakers are quite large.
Low-end Limitation: They only reach down to 35hz with boundary loading.
Horizontal Coverage: It's not as wide as I'd like.
Practicality: The horn on top is a bit of a concern, especially with baby GG² about to start walking.



As you can see below the measured 'anechoic' response yields quite a bit more low-end extension when in the listening position. I thought this would be fine but there has been the odd movie or song that lacks a little in the rumble department. Boundary loading really is my friend here (more on that later).




Shortly after building these I added Dirac and that improved things a lot over my manual room correction (manual not shown).



When I made my workshop speakers (here) I really enjoyed the sound of the B&C 5CXN44 coaxial drivers and found that they gave quite a nice wide image even when I am at the end of the sofa. I think this is because of the diffraction and tuning the response to work best slightly off axis due to the choppy response a 0 degrees.



SO...

An idea I have been chucking around in my head for a couple of weeks is this:

A more compact floorstander using an SB Acoustics SB15SFCR39 for bass in a vented enclosure, extending further down to the early 20hz with boundary/room loading. For mid and high, the B&C 5CXN44 in a sealed enclosure. Both drivers would share the floorstanding unit, reducing both physical and perceived space.

SB15SFCR39 ≈ 26L / 35hz vented
5CXN44 ≈ 4L sealed

I am totally up for other drivers but I don't want to go beyond 200mm wide baffle and I'm not too keen on a side mounted woofer owing to little fingers.

Things I have for sale, using this FifoPi Q3+ReclockPi in this very moment with GK154 clocks, so will disassemble if enough interest is met:

Iancanada FifoPi Q3 w standard clocks 120eur
Iancanada ReclockPi 60eur
Iancanada FemtoClock 45-49MHz clocks (these are the FifoPi Q7 II clocks), 120eur for the pair
Russian GK154 11-12MHz clocks, 120eur for the pair (these work best at 5VDC)
Iancanada SC-Pure 24,576MHz clock, 200eur for this single clock

Will offer discount for multiple items, net shipping cost will be added at buyer expenses and risks, thanks for looking

Selling 12pcs 33R +-1% 50W NHS50 Ohmite/Arcol brand new power resistors, 6€ each or 60€ + shipping expenses takes all.

ESS has released new ADC flagship models, improving on their previous generation of flagship ADCs:
https://www.esstech.com/products-overview/analog-to-digital-converters/

Main differences are the Hyperstream IV modulators (as known from their latest DACs), lower noise and improved THD, more DSP power with direct code load from an SPI EEPROM, and larger digital gain ranges.

As usual, beware of ESS' reference schematics. The "recommended input circuit", for example, does not correctly work for a balanced input without signal symmetry ;-)