I have recently updated my iMac (M1 chip, SSD) and run Parallels Desktop for work, and all sorts of Window 11 software, including VituixCad, all good, and iMac runs both Op Systems simultaneously. So, I ordered the DATS V3 system.

While the software loads properly, it does not recognize the box connection (nor keyboard inputs) even though I have set input and output to its (USB via lightning bolt converter) USB Audio Codec connection, per the directions. Parallels states its because the software has not been upgraded to ARM architecture?

Ed P, over at Midwest Audio Club suggested I contact you on this forum.

Is there something I can set / do differently to get the measuring box to communicate through the connection?

If not, can the DATS V3 measuring box work with REW which runs directly on my iMac’s operating system?

Thanks in advance.
Andy

Excuse me everyone , im kind a getting confused and my head is turning around also dillema about my single rail class d amplifier waveform output, is this good waveform or the worst amplification and/or just the weird audio amplifier i've made so i really hoping the suggestion and a bit help,
here is the waveform picture,also be able to see the detail waveform in pdf

Some info about this amplifier : fullbridge , supply source at 64V single rail , 4Ohm Load , input signal injected at 500hz , sawtooth signal something around 450Khz




Also If anyone who interesting to saw the schematic (might be none😄) i will drop it in this post

I'm looking for a decent 24dB LR 2- or 3-way active crossover, a pair or quad of boards or a complete device from EU only, it is always too much of a hassle with the darn german customs.

Hi there

can you model ‘ports’ (that is to say channels from the chamber of a synergy horn, which radiate into a point offset further along the horn’s length) in Hornresp?

thanks

I can see the Horns forum in the menu (see attached) but am unable to access it and I have a new thread I want to start regarding a corner horn

😀

Could someone give me some insight into how Acoustat types are constructed. I believe I understand most of it.
what I'm mostly confused on is.
Do you make one side of a cube louver by applying the wires to the louver, apply the spacers to the cube louver, then glue the stretched membrane to the spacers, repeat for the back side cube louver.
I thought the Acoustat was somewhat dis-assembleable? If so, this would be permanent.
Is there a better way?
Thanks
Paul

Hello,
I do have a receiver make Technics SA-424. It was stored in the dry basement for many years. As it is today raining cats and dogs, I grabbed the "forgotten" receiver and cassette deck RS-M260, hooked them up to the power line and speakers. However, I had to realize that the tuner did not function at all. The receiver has a buildt in analog and digital metering to show the frequency selected. Both did not work. Except the analog meter (to show the field strenght) at least lit up, nothing else. The ability to select the preset channels and to tune is completely lost. All the LED diodes did not light up. The LCD scale to show the channel frequency selected was dead, too.
However, the amplifier works very well in conjuction with the cassette deck. Pretty good sound.
To tell you I'm lost at the moment. Beforehand opening the receiver, I would like to spread the information into the forum. May be anybody has an idea how to remedy the problem. I hope, that there is an easy solution to remedy the problem reported, e.g. a microfuse to be replaced etc.
Thanks for a qualified answer.

SOLD!​

Hi,

Due to a request i remembered that i still have spare parts for this project, these pcbs and some new / unused part ... some not more available at DigiKey / Mouseror or EOL.



PCBs:

• DAM1021 input board V2.3
• DAM1021 front panael - switch board V2.3
• RPi connector V2.2

Parts (like Toslink & SPDIF connector, MOSFet, heat sink, digital transformer, Norlin switch, ...):
around 40€

SOLD!​

Cost: 50€
Shipping germany (without islands): 6€ (trackable & insured)
Shipping: 20€ world wide (not trackable & not insured)
Shipping: 25€ world wide (trackable & insured)

Hi amigos,



I am selling my NC502MP Module + Cable Set. (2x350W / 8R or 1200W / 8R bridged).

Free Shipment to Europe only.



It is like new.

Well known module, excellent perf. great for any DIY projects

See Measurements @ ASR

470€ shipped for free + I offer cables set



SPEC :



Hypex NCore NC502MP twin Channel Module

PSU SMPS integradted 1200W

Nord Switchable RCA-XLR input board

Auto sensing 100-240V mains input operation

0.5W standby operation

1.5KW Main PSU

47K Ohms Input Impedance, low output impedance

THD 0.0018%

S/N Ratio 116dB

26dB Voltage Gain

1X1200W 8 ohms bridged

2 x 350W 8 Ohms

2 x 500W 4 Ohms

2 x 450W 2 Ohms

Fully loaded flat frequency response






92% efficient

im building a binaural mic with my son.
Parts are mainly 3d printed ears and acoustic dividers an usb soundcard with stereo mic inputs and two cheap electret lavalier mics (electret capsules).
For a first test i resoldered the two microphone cables to a stereo jack and tested them with the usb soundcard. They work well, only problem is an about 9db volume difference between them.
I dont want to replace them with higher quality electrets in the first tests so what would be the best option to match them? can i use an l-pad on the louder one? or is there a trick to have higher gains on the lower volume one?
Recommened resistor values?

im asking because im not sure what happens when i add like an l-pad and that of course changes the support voltage too
.

10:04 AM 9/21/2022
Hello,
This is a question about the F5 First Watt clone. We built one from parts purchased from DIY. I say "we" built it because a professional colleague is building it for me. It works, but it isn't matching the published voltage on the measurement to adjust bias.
On the first startup we blew the P channel MOSFET (Q4) on one channel because we did not understand the adjustment procedure. I purchased a new kit of MOSFETS and the BJT limiter transistors (Q5, Q6) from DIYAUDIO. We replaced both MOSFETS and the limiter transistors on the blown channel and tried again.

The P channel MOSFET I received in the replacement parts kit is not the same as the original and I questioned that and was assured it was an upgrade. The original was the IRFP 9240 and the upgrade is the IRFP 9141. We did not change the working channel MOSFETs and left the IRFP 9240 in the working channel. This was to keep a spare MOSFET if needed. Why would we need a spare? Smile.

We don't have a variac and used the old trick of houshold light bulbs in series with the AC input to keep things from getting out of hand too quickly. After verifying things were OK, we removed the series light bulbs. Both channels work and have very low DC offset voltage in addition to the ability to play audio.

But, the two channels are very different from each other and also very different from the published bias. The DC supply is +- 23 and is based on the DIY PSU board and published schematic in the DIY build guide. We did not have the PSU board at first and used caps clamped to the chassis floor and a bridge bolted to the front panel.

We can't get the bias past a tenth of the published value of .59 on either channel; we are running at about .059 on both channels. Attached is a table of the values we have. After our first experience of blowing the MOSFET, we watched the voltage drop across the .47 source resistors(R7, R8) as a safety check of power dissipation.

In channel 1 the drop across the source resistors is about 0.700 volts as in the table. In channel 2 the drop across the source resistors is about 0.13 volts. Both channels, as noted above have the same balanced drops across R9 and R11. Channel 1 is running about the right heat to the touch and channel 2 is barely warm to the touch which would be the case with the low drop we see across the source resistors.

We believe that the input JFETS are OK based on voltage measurements and the ability to play audio seems to confirm this. The same input level of audio produces the same output level, as measured by ear, in both channels. P3 was adjusted to the middle mechanically before startup and adjusted for equal drop across R3 and R4.

I am going to ask my colleague, Michael, to describe what happens when he attempts to raise the bias using P1 and P2.

…… Both the channels will only balance at about 0.52 to 0.58 volts. When an attempt is made to go to a high balance point the amount of imbalance stabilizes at about 0.125 volts. At this point adjusting either P1 or P2 drives both voltages in the same direction maintaining the 0.125 volt imbalance. When the higher of the balance voltages reaches the 0.59 volt range the drop across the source resistors gets near or above 1.25 volts which drives the source resistors to 3 watts.……

Thanks for any suggestions. It strikes me that the .7 current across the source resistor is about rith, but why is the bias so low? Attached is table of measured voltages.

There was an amp I worked years ago called the CFH7. More info on that thread here. It was basically a VSSA current feedback front end married to the Class AB hexFET output stage of the FH9. After some mods and testing by other members, most notably, Thimios who identified some oscillations and how to fix them, we went on to make higher output device counts on this amp. We ended up at 2 output pairs (4), 2 drivers, a Vbe multiplier temperature compensation (1), and the input pair (2) for 9 actives. A member added a cap multiplier for each rail to clean up the front end rails which is technically 2 more. The name remained at CFH9 but had a CX designation for the cap multiplier. Technically it’s a CFH11CX2. The naming follows Apex Audio’s convention: C for current feedback amp, F for FET output stage, H for hexFET (vs laterals), 11 for number of actives, we added CX, for cap multiplier, I added the 2 for second generation. A big thanks to the others who provided help, discussions, inspiration, and assistance in testing and layouts: Shaan, Gaborbela, Thimios, Apex Audio, Mjona, MG2016, Ashok, Thiago, Saddevil,… it really was a community project.

It’s a very simple amp:


But the predicted performance is quite amazing - here is 1W info 8ohms, essentially no distortion (THD is 0.000023% - that’s 0.2ppm - in reality it won’t achieve that due to imperfect models or parts but we get the idea that it can be very transparent given such a low parts count):


Here is a bit more power 50Vpp into 8ohms:


A nice layout was made by Thiago and that has recently been verified to work by fazildiken:


Fazildiken’s build:


This was my CFH9 with MG2016’s layout being tested:


Square wave test:


I even had it running as stereo on a plank amp:


I am thinking of taking this as a starting point and doing a few more mods to it and maybe a new layout one of these days. No rush on this project but just getting it out there and to start thinking about it.

Hi,

I am building a dedicated power supply chassis for my preamps. I want to have a box with 3 independent power supplies for L & R channel plus volume control (Muses from Academy Audio).

My system:

• Miro’s DAC based on AD 1862, common ground for L & R channel
• Preamps (BA3 & Wayne's 2018 Linestage), dedicated grounds for L & R
• 2x Aleph J monoblocks

Power supply for preamps:

• 2x Salas shunt regulator for L & R channel +-24V
• 1x Mark’s VDRN (not populated yet) for Academy Audio VCU Muses 72320 volume control +-15V

Questions to preamp PSU:

• All PSU will be connected via dedicated CL-130 (50 Ohm). I have those available. Is 50 Ohm ok or better to use 10 Ohm resistor 2W (also o?
• Earthing from power chassis to the preamp chassis. I can use one of the wires for that. It is 0.5mm2 = 20 AWG copper. Sufficient?
• Shielding. The cable has mesh shield – picture. I can connect the shielding to metal plugs on both sides. This will form another earthing connection between Preamp chassis and the PSU chassis. Is that a right way of doing that?
• I do not connect left and right channel grounds at any point expect the Muses volume control. I assume this is the best option as per Academy Audio Manual: “The VCU board features separate connections for the Left (Com_L) and Right (Com_R) analog grounds. These grounds are connected on the board to minimize cross talk. It is recommended to use isolated ground audio connectors to ensure the lowest cross talk and noise pick-up.”

Few pictures attached.

Thanks

Hi, i'm searching for Stax female panel connector, also diy projects

Hello Everyone,
Today, I pulled out and powered up an old Hafler P1000 amplifier that I had stored in a closet for many years. When I powered it up I immediately noticed a faint humming noise. This noise is coming from the actual amplifier assembly. I can feel the chassis vibrate.

The audio signal is clean, meaning that there is no obvious or audible ground loop hum in the speakers.

It occurs to me that it may be good to replace the power supply filter caps,

Is that too simplistic of a response?

Can you share any insights or advice?

Thank you.

Does anyone know where I can get a large knob which measures about 2” or 2-1/4” in diameter for a DIY preamp project? I have been all over the net but can’t seem to find anything larger 1.5”. Thank you in advance

Hi, I have a musical fidelity A100 which runs like a wok. To my regret, I happened to forget to turn it off last night, and when I was back from work tonight it was as hot as a volcano.

I quickly turned it off and scrubbed it with semi-wet cloth to cool it down.

After an hour or so, the amp was powered up for check. Power was ok, but no sound. I'm sure it's not the thermal fuse, as the thermal fuse failure doesn't turn it on at all.

Any idea is appreciated. Thanks,

Hi folks tubes aren't exactly my area of expertise so I'd be happy if someone could cast an eye over the listing for a cheap kit I found. It even has pics of the board and a circuit diagram which seems quite rare for an eBay listing. https://www.ebay.com/itm/154151985365

Cheers. D

I'm kind of leaning towards adding a subwoofer to give it a slight boost up to say ~60hz, music is the priority though I use the stereo when I watch films as well.
I've modeled a lot of different subwoofers in WinISD to see what looks good on paper, but that doesn't tell me much more so I figured I would ask if someone has some hands-on experience with any of them, maybe one I should avoid (or possibly another one that you might suggest).
Now as always, price is a big concern, size of the box could easily become one (with one sub I need to be able on position it right), and it does need to have a reasonable sensitivity as I'm not going to add a massive amplifier (leaning towards Dayton SPA300-D).

SB Acoustic SB34SWNRX-75-6 (looks great vented, at the upper end of price)
https://sbacoustics.com/product/12in-sb34swnrx-s75-6-norex/

Dayton Audio DCS305-4 (models about the same as the SB, price is better)
https://www.daytonaudio.com/product/39/dcs305-4-12-classic-subwoofer-4-ohm

Earthquake Tremor-X 124 (in closed enclosure it's close to the two above, might lose a little bellow 30Hz, on sale right now in Europe so it cost about the same as the Dayton)
https://www.earthquakesound.com/ind.../car-products/car-subwoofers/item/tremor-x124

Earthquake Tremor-X 154 (in closed enclosure it still need a bit of box volume, but does produce another 4dB or so over the others)
https://www.earthquakesound.com/ind.../car-products/car-subwoofers/item/tremor-x154

Has anyone built this preamp from Linear Audio Volume 5?

Linear Audio | your tech audio resource

Edit April 5, 2019: Beautiful example of this amp in finished case by Avtech23 on post 425.




*****

This is a simple DC-coupled high performance SE Class A headphone amplifier design by member TimS who has approved this GB. The design uses four cascoded BF862 JFETs on the input stage. They provide compensation for DC drift and the amp has stable DC offset of less than 5mV. The design has a dynamic CCS, reminiscent of an Aleph to provide good efficiency and low distortion from two P-channel MOSFETs in the output stage. Simulations show very low THD in the sub 1 part per million (PPM) range for 5vpp into 55ohms for a 400mA bias current. At this bias, the heat output is about 14w per channel and allows it to be used as fleawatt speaker amp and able to drive 8ohm speakers to 1.5w with 0.004% THD. Increasing the main source/drain resistors to 2.7ohms sets the bias current at about 115mA and this has very good performance. I built a hand etched prototype and measurements and listening shows a very powerful, dynamic, and clean sounding amplifier. The GB boards will be high quality 1.6mm thick with 1oz copper and ENIG gold finish with blue solder mask.

Here is LTSpice schematic and DC setpoints for simulation:


Predicted FFT for 5vpp into 55ohms with 400mA bias:

Here is hand etched prototype:


Measured FFT for 115mA bias 1vpp into 42ohms - note that elevated H2 distortion peak is probably a component choice of the lwo cost prototype (cheap steel leads on resistor, etc). I am quite sure that a proper amp using a real PCB and all high quality resistors and MOSFETs will be superior:


Measured 1kHz sine wave at 17.6vpp for 115mA bias and +/-15v rails for almost 1wrms into 42ohm load


10kHz 2.5vpp square wave - nearly perfect performance with no overshoot, or ringing:


This is the schematic for production PCB:


Here is the layout by JPS64:


Here is 3d render of PCB with components (bottom side):


3d render of PCB with components (top side):


How does it sound? Very dynamic, transparent, open with deep deep bass. It is DC coupled in and out so there is no capacitor to color the sound. The distortion is very low and you have to be careful not to play your headphones too loud if you are used to judging loudness by distortion. It's a great little amp that is easy to build with relatively low cost parts, yet is very high performing. Compare the predicted distortion levels with amps using 5x as many transistors. The nice feature about this amp is the rather high output power it is capable of and a rather high gain close to 20dB that allows one to drive an inefficient set of planar magnetic headphones to loud+ levels with very low distortion.

If there is interest, please add your name to GB interest list. Cost will be about $28/set and shipping will be $5 in US, $10 in Canada, $15 everywhere else.

Update July 3, 2018;

The FFT of the wall mains powered 12v to the on-board ultra low noise DC-DC dual rail PSU has noise characteristics resembling a battery. Note total absence of 60Hz/120Hz/180Hz/240Hz mains peaks and how low the "grass" of the noise floor is:


Here is the final design for production, and it is an 8 panel board that contains:

• input and source switch board (only preamplifier version)
• crossfeed board (with defeat Xfeed ON/OFF switch)
• headphone jack output board (6.35mm stere TRS output jack)
• volume potentiometer board (with the possibility of three different types of pots)
• PSU (includes CLC, DC-DC dual rail step up, cap Mx, CRCRC filter to produce battery-like rails from simple 12v wall-wart)
• CLC filter board (in case you want to use your own PSU)
• ON/OFF switch board
• amplifier board

The above boards can be mixed and matched and connected for either an HPA or a preamp following this diagram:


Schematics and other data here:
Simple High Performance DC Coupled Class A HPA with sub PPM THD - Page 10 - diyAudio

Top side:


Other side:


Mounted in a popular all CNC'd $36 Aliexpress case as a HPA, it looks like this:


Here is rear view of HPA:


As a preamp with your own machined panels, it looks like this:


Rear view of preamp:


Edit July 21, 2018: final schematics and stuffing guide here:

Simple High Performance DC Coupled Class A HPA with sub PPM THD - Page 10 - diyAudio

Update Aug. 4, 2018: Schematic Update! Please use this schematic for the PSU as the original has a few typos.

Update Aug. 5, 2018: Silkscreen on PSU PCB has error: Diode V241 has cathode and anode flipped.. Mount diode with Anode towards Drain of P channel MOSFET on cap Mx.

Update Aug. 27, 2018: verification build of GB boards completed. Amp sounds superb and measures very well. Here is FFT for 1vpp into 51ohms - very similar to earlier measurement but much lower distortion.




Update Sept 2, 2018: BOM from verification build can be found here.
Simple High Performance DC Coupled Class A HPA with sub PPM THD - Page 24 - diyAudio

Two AN-3225 transformers for sale.
excellent condition.
$66 for both includes shipping.

Project Overview:
1. The project will be for a 'modular' (I will explain this below) 3 way plus subwoofer configuration in a 0.56 cubic foot Dayton/Denovo cabinet.
2. The cabinet will share the 7" or 8" woofer and whatever midrange is selected.
3. The cabinet's interior is limited to a 7" cutout but given that the actual driver will be mounted in the baffle and that it tapers toward the magnet I can probably get up to 7 1/4 inch cutouts in this cabinet by using a dremel to lightly remove small 1/8" areas from the MDF of the interior walls on each side (maximum) without violating the integrity of the cabinet.
4. I am going for a 'sealed' configuration for easy integration with the 2 x subwoofers.
5. The speaker will be 100% active and audiolense XO automatically time aligns to minimum phase or linear phase depending on your choice so from a crossover perspective all I have to feed audiolense are a few things as shown below. Audiolense will automatically flatten the response using psychoacoustic algorithms to whatever curve you've drawn up for the overall speaker response peaks and such are automatically handled. Dips however are a concern as I prefer only to cut not boost so big dips likely will reduce overall speaker sensitivity.
a. The crossover point between each driver.
b. The 'octave width' of the crossover point. I can make digital slopes that are EXTREMELY steep, I've successfully used 0.5 octaves for the crossover point width before.
c. A target response config/room curve i.e. whatever I draw, the harman curve, B&K curve, toole curve, etc.
d. The 'correction' profile i.e. if I want per driver time alignment, phase type, number of taps per correction file, etc.
6. Each driver will have it's own dedicated amp channel of 80wpc capable of 4 or 8 ohm loads so likely 4 is preferred in all cases to get the additional sensitivity out of the driver.
7. The room is my office and is maybe 10' x 16'. I sit at one end of the narrow range of the rectangle.
8. The speakers will be stand mounted 4-6' out from me on either side.
9. I listen at moderate levels, ideally I would like to target output levels of 89-94db with very low distortion or strain on the drivers, I don't really care about MAX SPL, what is more pertinent is that I be able to listen in that 89-94db range with no audible strain/distortion.
10. I would like to spend under or around $100 per midrange or midbass driver. If there are compelling reasons to spend more I will entertain them for sure.
11. I like 'detailed' in a driver versus 'analytical' i.e. I want a lot of detail but not to subjectively enter analytical territory where any music that isn't perfectly recorded sounds granular/grainy.
12. I listen to all types of music. This will be 100% for music not HT.
13. Given that my office is an audio laboratory I don't care - at all - about driver appearance or WAF. These drivers can be as ugly as we want.


Alternately:
I could make a dedicated cabinet for the 8" woofer that stands on it's own and then 'stack' the other modules for the midrange and tweeter on top of it if we encounter cabinet volume limitations that are compelling. I would use a piece of ISO rubber (Bridgestone ISO pond liner) between each 'module' for isolation.


Details:
1. Subwoofers are dual M&K MX70B's. They are about -4db at 20hz and are +1-2db once you hit 30hz or so.
2. Active crossovers will be implemented using Audiolense Convolver and Audiolense XO.
3. By modular I mean this. 1. My cabinet has around 6 pairs of front baffles of the same size that have been pre-cut that I can swap in and out using 6 x machine screws that go into threaded inserts in the actual cabinet. This lets me swap speaker configurations at any time and then simply select the convolution file that matches to that 'speaker'.
4. On the baffle I intend to have a cutout for the 8" bass driver and above it the cutout for the midrange driver. The tweeter/waveguide will sit on top of the speaker. I have a ton of little precut stand alone baffles on L brackets that I set on top of this stand mount making it 'modular' in the tweeter section as well.
5. I usually cross both M&K subs at around 80-120hz (I know I'm getting a little directional if go over 80hz) depending on the configuration of the drivers currently in the box/swappable baffles.


Questions:
1. The speakers will be angled facing me on each side. Does this mean that since I'm always on access that beaming of driver is less of a variable or no variable as far as driver selection goes?
2. Should I build sub-enclosures for the midrange inside the box or is it fine if the midwoofer/midbass driver share the same air volume in the sealed enclosure? This will likely be a variable on if I share the cabinet or go fully modular with separate enclosures.
3. Driver selection....bring it! I'm open to all manner of suggestions, the ones I have suggested were just based on research.
4. Crossover points, again, bring it! I'm open to suggestions.

Driver Selection Options:
Woofer/midbass
1. Dayton RS225-4
a. I'm assuming I'd go 4 ohms go squeeze as much out as I can unless there is a compelling reason not to.
b. Do I go for aluminum or paper?
c. Perennial recommendation regarding low distortion and high value in many threads.

d. Looks like I can get flat response from just short of 100hz (which is fine) until maybe 1500-1600khz at which I'll need to hand off to the midrange. I am far more likely to do this at around 500hz or so.
e. Dayton RS225p-4a frequency response below. Not sure which one is preferable, would love to hear advice:



2. Dayton PA-200.
a. High output pro woofer.
b. Efficient and nice looking performance graphs for this application see below:


3. Peerless by Tymphany 830869 8" Nomex Cone HDS Woofer - Cutout too large at near 7.5 inches.
4. FaitalPRO 8FE200 8" Professional Midbass 8 Ohm and/or FaitalPRO 8FE300 8" Professional Midbass 8 Ohm
- Maybe an option but Sealed 43 is slightly over 100 hz which isn't optimal. Given that it's efficient I could probably flatten the entire frequency to compensate for it and still not have significantly lost efficiency.
5. Peerless SLS 830667, 8" - Frequently recommended option, the Dayton seems better based on graphs/specs as far as I can tell.
6. SB Acoustics SB20PFCR30-4 8" Paper Cone Woofer- 4 ohm-Looks really good for a really low price but who knows how it sounds/distortion specs.
7. Classic P21WO20 8" Woofer Poly Cone, looks like a remake of the scan-speak by Madisound.
8. SB Acoustics SB23NRXS45-4, 8" Woofer
9. Scan-Speak Discovery, 22W/4534G00, 8" Midwoofer, 4 ohm

Midrange/Full Range:

1. I already have the venerable Tymphany TC9FD18-08 and Tectonic TEBM65C20F-8 3-1/2" BMR Full-Range Speaker 8 Ohm
2. Dayton Audio RS100-4 4" Reference Full-Range Driver 4 Ohm and Dayton Audio RS100P-4 4" Reference Paper Woofer 4 Ohm - Well loved and commonly used.
3. Dynavox LY401F 4" Full-Range Driver: Fascinated by this driver.
4. Faitalpro FE32: Not sure why I'd pick the Neo but it's in here in case I'm missing something.
5. Faitalpro FE35 This seems like a stellar candidate, might be near the top of my draft pick list. I'm not quite sure how to mount this to avoid issues/diffraction.
6. Tymphany NE149-04 seems popular but inefficient to a degree but not prohibitively so.
7. Tang Band W4-1337SDF 4" Titanium Full Range Speaker
8. Tang Band W5-2143 5" Paper Cone Full Range Driver 8 Ohm
9. Tang Band W5-1611SAF 5" Full Range Speaker
10. Tang Band W4-2142 4" Paper Cone Full Range Driver 8 Ohm
10. Peerless By Tymphany NE123W-08 4" Full Range Woofer Speaker again seems popular but inefficient.
11. Dayton Audio RS52FN-8 2" Reference Fabric Dome Midrange 8 Ohm/Dayton Audio RS52AN-8 2" Reference Aluminum Dome Midrange - Lots of discussion regarding these.

12. Visaton B 80 3.3" Full-Range Driver 8 Ohm​

13. SB Acoustics SB12MNRX2-25-04​

14. SB15MFC30​

15. SB15CAC
16. BMS 5S117 $137
17. Scanspeak Discovery 10F/4424G, 4" Midrange 4 ohm
18. Lots of recommendations for Morel MDM55 dome.
19. Beyma 3FR30
20. b&c 3.5NDF26
21. Scanspeak 15M/4624G Discovery, 5.5" Midrange

Crossover Points:​

1. Woofer to midbass/woofer anywhere from 80-120hz, lower is better.
2. Midbass to midrange around 500hz to avoid having a crossover point in the critical lower end range unless I'm off target on this.
3. Midrange to tweeter -> Given that this is a modular design the ability to crossover higher is better to maximize my choice of tweeters and reduce the strain upon them. This is all TBD. Probably the most demanding tweeter that I own as far as needing to be crossed over high is a pair of cheap Foster E100T10's whose response is below. I don't HAVE to design around these, it would just be nice to have them as an option:

Seeing much use of Litz wire in higher-end IEM cables and third-party cables. E.g., "silver 22 AWG" Lttz, etc.
For example:
https://www.aliexpress.com/item/2255800651290793.html
Not sure what the above is comprised of? The description says: Bold high-purity oxygen-free copper silver plated earphone upgrade cable, single core 63 cores * 4 strands, outer diameter 4.5-5.0
Anyone have experience with IEM cables?

Hi all,
Please, I need some advice on this amplifier, because after ten years of SET, I needed an amp capable of driving speakers at 2 ohms, after trying it, it is his job without problem, as the sound is pretty good, I wanted to restore it, as some components are not original.
This is where I need your skills, whether it's worth changing the Predriver, are the transistors Q3, Q4, Q5, Q6 on the diagram.
On my amp they are MPSA05, MPSA55K, they seem to be matched (small paint strokes).
I wanted to put the sa818y, sc1628y, they are expensive, but I can get them,
bandwidth is not the same, is that it can change the sound?, is that it is a mistake to try to change them?
Transistors for power on the left channel, there are ARC4700C, 4800B, for the right, MJ15024, mj15025.
There are some small differences sound between the two, is it better to put the same motorola, or the ST2121, ST5949?
I also have a question for Mr.llwhtt, please, is it I could get the procedure to adjust this amp?
Thank you,
Best Regards.
Stefano

Hi folks, a few months back I got a VERY cheap TPA 3118 board to play with. It's surprising decent sounding considering the board cost less than I can buy the chip for...
Anyway it's actually quite good with acoustic and classical music but not so good with rock etc. It's a bit bright/forward and can get tiring after a while.

So yesterday I ordered a through hole version of a TPA 3116 from eBay. It appears to be a Juan Jing board from what I can see but has no name in the listing https://www.ebay.co.uk/itm/325329965300

Anyway I keep coming across posts about using these with a tube preamp but as I'm on a very low budget now I ruled it out. Then I found this listing...
https://www.ebay.co.uk/itm/403782119412 could a valve preamp possibly be any good at that price?

It's going to be a few weeks until the 3116 board turns up so I have time to look around. I could probably fit both boards inside the one vented enclosure I already have.....

Then I looked on AliExpress and found this board...
https://www.aliexpress.com/item/33006452629.html

According to the listing "Playable sex is very high" ....🤣 how can a chap refuse......

Anyway back in the real universe, what do you guys think? Is either of these likely to be half decent? Can anyone suggest a similarly cheap but reasonable alternative? I'm obviously not looking for high end sq but I do need low noise. My speakers are Rega R3 mini floor standers which are decent but bright sounding. I can't afford to change them so I need an amp that's quite close to valve/tube in performance but with tighter bass.

Thanks for looking. D

I have a pair of Avi Audio ADM9T active speakers… one of them recently started buzzing as soon as it gets power. I strongly suspect the PNP output transistor is the cause, but I can't find any US-based distributors who still sell these transistors (Sanken has them marked obsolete). Does anyone know where I can get ahold of them besides eBay/AliExpress (not sure I'm ready to trust them for potentially used ICs). Ideally, I'd like to buy two or three pairs of STD03P/N transistors.

Dear,

I have power amplifier Audio Research D-100b.

Analog Module type AM-2 not working.

I want buy Analog Module type AM-2.

Contact: hieubui212@gmail.com

Thanks,

Guys, I think I already know the general answer but I wanted to check and make sure I'm in the ballpark.

I have a 2x10 sealed bass guitar cabinet I want to port.
The drivers are meant to be in a ported cab.
I have all sorts of calculators for figuring out the size and length and I have all the speaker parameters and I think I'm ready to go but I do have one question.

The two woofers are essentially in separate cabinets with a solid piece of wood splitting the cab in two .... there is a small opening between the two sides where the jack plate is ... but only about a 2x1 cutout.
Ports will have to go on the back
The easiest thing to do would be to simply use two ports, one for each side.

So my question is when calculating the port size/length do I just treat each side as a separate cab or do I figure it out based on the entire cab volume?
And if it needs to be the entire cab then how do I plug in values for two drivers?

I'm probably overthinking this and imagine I should just treat each driver as being in its own enclosure since they basically are.
But before I cut holes in my cab I wanted to run it by the experts.

Anyone out there want to sell their finished & working in good order Badger/Wolverine amp project? Please let me know. Thanks.

I’m a big fan of fullrange drivers because they have no crossover in the region where the ear is the most sensitive. But I’m also aware of the disadvantages of fullrange systems so I want to try to design a 3 way speaker that avoids a crossover in that region but still got a good dispertion and no resonances in the passband. In my experience the passband where the ear is the most sensitive to that is between 400Hz and 3.5kHz.

Tweeter and woofer is no issue to find, but it’s hard to find a midband driver that does that band clean and with a good dispertion, so I’m looking for your advice. Dome mids were my first thought, but most don’t do that full region, they can’t get low enough. Cone drivers mostly don’t do it clean to 3.5 a 4Khz as they start to beam or resonate. So my question is, do you know drivers that can do that, and that are reasonable priced. I know smaller Mark Audio drivers can do that, so that may be an option, but I’m looking for a project without those (as I already have a few in my home).

System I had in mind is about 88dB efficient with a 1” tweeter and one or two 8” woofers. For mid I think the best would be a 3 to 5” cone mid or a 2-3” dome mid. Crossovers are not decided yet (i do that after i have the drivers and cabinets), but it’s a big chance I do it passive (as I like those more). It’s a long term project (I got quiet a few others in the pipeline), but as I’m very slow in my developments of designs, it does not harm to start already with that.

So what mid drivers do you suggest for this project?

HI

Does anyone have the service manual for Accuphase M1000 mono power amps?

Your help would be greatly appreciated!

Cheers,

Tim

how can i convert 40vto 28v with resistor which i use to convert please help full reply

Hi guys.
I bought a CD player Sony, but the display stick was broken in transit. The tube is broken, in which I think there is some gas. Other functions work.
What can be done about it? Are there such spare parts?

Cheers!

I'm not raising a problem but am simply curious: what do Reaction Score and Level indicate? The terms are associated with each member, and I just wonder what they mean.

I'm slightly puzzled that some factory cd's seem to be rubbing on something while playing. They have to differ in thickness slightly and it affects the playback with a " ticking " mechanical sound. Anybody encountered this problem? I don't want to poke blindly with my fat fingers and break the machine.

…..or maybe?……the MT section isn’t firm yet but the dipole bass has been designed and 8 woofers are on the way. I’ll be using these
https://www.parts-express.com/GRS-12PR-4-12-Paper-Cone-Rubber-Surround-Subwoofer-4-Ohm-292-820

Two 72” tall towers with 4 drivers in each in an H frame alignment unless someone offers up an improvement using a U frame.….I’m not sure there’s a viable argument either way though since these won’t be asked to do much above 100hz. I can’t find a viable argument for or against drivers mounted opposing either…..from a visual perspective, I’d rather not look at magnets unless someone can make a case?

I’m 55 now and the plan is this will be my silver system…….it needs to take me to where and when my hearing loss no longer justifies high end performance is you know what I mean. The space they’ll be in is where they’ll stay permanently……I doubt I’ll be able to take them with me to the old age home when the time comes! Lol. We’ve got 36” behind and to the side walls available and 10ft between them so enough room for them to breathe in a dipole situation.

Power will be handled by two class D amps mono with DSP. The woofers have enough linear excursion to get the job done and the combine efficiency should suffice. Total Q isn’t bad at .43 and if I understand it, the dipole alignment will increase total Q as well.

Once built before final finish work, I’ll tweak these along with my current diy MTMs which are sealed boxes before moving on to the hybrid array MT section……for now more of a proof of concept that dipole bass is the ultimate for music. For HT use, the 18” servo sub that lives as a DIY end table will remain for the lowest octave.….I get an F3 of around 20 with it now and an F10 of around 15 with room gain.

Once woofers arrive and have been tested for consistency, I’ll post an update and rough drawings of the enclosures. Plinths will be 3” thick layered MDF since I already have so many scraps of the stuff. Cabinet will likely be BB with Walnut veneer and rubber piping grills sans Sonus Faber design….love that look!

Ive also given some consideration to an Aluminum extrusion truss design with wood accents where the extruded truss would offer the structural component with the wood used for the baffle. If anyone has a thought, I’d love to hear your ideas. End of the day if you consider he cost of BB plywood, premium veneer, materials and time……I think we’re still in apples to apples territory.

Thanks for reading…..this is gonna be a long journey for us to take together.

I've been building speakers for quite some time now, and to this day I've never come up with a reliable way to measure anything below ~300 Hz (anything below that is a hot mess, more a reflection of the room than the speaker itself). Things I've tried...

*Putting the mic in the port- this is what some recommend, but my findings are that the f3 is generally way too high using this method. So either the theoretical cabinet design software is wrong, or this method is not an accurate reflection of reality.

*Near field- take the NF measurement, then splice that into the actual measurement around 300 Hz. This seems to be the best method, though not entirely accurate if I'm using a woofer crossed at 300 Hz.

And I don't believe it's just me, a little later I'll post with 2 different measurements once I get screenshots of them, taken by 2 different magazines of the same PSB Imagine T2 speaker, and those 2 measurements are vastly different. I'll be honest, most of my speakers are done by ear below 300 Hz because I don't trust the measurements (aside from impedance). If you guys are willing to share, how do you get the most reliable measurement below 300 Hz?

I am restoring a P3000 Hafler. If I understand well, each channel needs a separate power supply (or separate secondaries) due to the transconductance nature of the design.
From the schematics, it appears that the center tap is 'floating', not connected to ground but to the positive speaker terminal.
Am I reading this correctly?

I got an old Croft Epoch Elite, but all tubes are removed. I looked at pictures in the internet, but there are many variants of the Elite out there, but not mine. What I can say is, that mine has the socket for the smaller valves (e.g. ECC82). I know that the phonopart works with 3 ECC83. What reamins in question are the two tubes (A and B) of the line level preamp part as shown on the picture (I drew this from my circuit). I cannot find a similar preamp circuit in www.

Anyone got an idea, what tubes A and B could be?

I am facing a problem that seems difficult to solve.
I have built a couple of lower voltage adjustable power supplies (0-30V and 0-50V in various variations), but I need now a higher voltage and adjustable current limiting power supply.

I have transformer with an 6 equivalent secondary voltage windings which are all with 4 wires parallel, diameter 2mm, all of these 6 windings provide equivalent 19Vac, with a power of about 2.5kVA (big toroidal transformer), so the transformer also allows a fairly large current.
The plan is to use it in the March 1990 issue of Radio Electronics https://archive.org/details/radio_electronics_1990-03 on pages 31 to 34 and page 69 in a "modification" of this power supply described by Reinhard Metz.

But since my transformer can provide significantly higher secondary voltage, I have given up on idea of using the LM317HVK high-voltage stabilizer.

Because I have an LR8N3-G adjustable voltage stabilizer that I would like to use because it technically meets the voltage requirements, - if it can be used?
(datasheet: https://ww1.microchip.com/downloads/en/DeviceDoc/20005399B.pdf )

Also I have 24 PNP-bipolar power transistors 2SA1962, 230V/15A to stabilize current, (datasheet: https://toshiba.semicon-storage.com...et_en_20131101.pdf?did=20429&prodName=2SA1962 )

There is a suitable 6 rack unit case which rear wall is almost entirely huge heatsink, the total area of the heatsink is about 25.000cm2 (close to 4000 sq.in) so it shouldn't be a problem to exchange lot of heat, generated during the stabilization in the worst case in linear mode?

Provided that I use power transformer step switching (for this there is a step switch with power relays, (picture of transformer secondary tap switching circuit board drawing is attached), unfortunately I do not have a tap-switching circuit diagram to provide, because it is drawn by hand on paper, but its working principle is quite simple - the output voltage from output of the power stabilizer controls tap switching relays as needed, switching them on and off in series, at least the 1st secondary winding of the transformer is always switched on and when the output voltage is increased above the value set by the zener regulator, the next winding is switched in series and so on, as the voltage decreases, it is switched off in the same way and excessive secondary windings, it allows to reduce the maximum losses during linear stabilization.

This part has been tested and works, but the power supply stabilizer (described also here: http://www.a-and-t-labs.com/K2_Lab_Power_Supply/ ) itself, which deals voltage and current regulation, gives me a headache. Since the maximum input voltages I use are about 3 times higher than those given in the referenced circuit, this would require changing circuitry - unfortunately, I'm a hobbyist and not strong in theory, so I'm in trouble and can't move forward with it.

The D3, D4 stabilitrons (from this circuit here: http://www.a-and-t-labs.com/K2_Lab_Power_Supply/powersupply_ckt_layout.pdf ) that track supply voltage of IC2 LF357 obviously need to be replaced, but have I confused myself or do I not understand starting point - on the basis of which I determine their stabilization voltages? Also R6, R7, R8 - I couldn't find an explanation of these elements in the article.
I have a power supply built according to this circuit and it has proven itself over about a decade of use without any errors. So I have taken this circuit (for some reason?) as an possible solution.

I don't object if the experts think that this is not a very good solution, but would someone please guide me in my questions, which I am having trouble with.
Or if someone can offer me a better solution, say 0...10 (not exactly strictly needed "0" but say also from 10Vdc is good) to 120VDC adjustable, current limiting PSU (however, I don't want to acquire exotic parts, it is also 100% important that I can use the existing power transformer and as a current stabilizer it would be best also if I can use existing PNP bipolar transistors - otherwise I am open to other options for such a power supply I could perhaps do it with less brain gymnastics).

I have looked in some service manuals of older, higher voltage regulated laboratory power supplies (for example by HP) but they are all based on primary side SCR circuitry and quite different in stabilization stage - could someone shed some light on me, why the use of an SCR preregulator is so preferred? Is it possible that my 6-stage switching method I designed is not a good solution? I don't need extremely high reliability compared to a well-known manufacturer's device, I just need a stabilized, current-limiting power supply with a relatively large adjustment range and higher current, also which I can built at home at the end of my knee, even with the hobbyist's limited resources (to ~200 euros+all existing components) in mind.

In existing parts:
1. Power transformer: 2.5kVA with 6 equal, 19V sec. windings, each consists 4 wires in parallel, 2mm diameter - so, good current capacity
2. I also have a 27000uF/200V capacitor bank as a power filter.
3. 100A bridge rectifier (4 stud mountable 1200V diodes with hardware),
all the necessary passive components for use in the referenced schematic ( http://www.a-and-t-labs.com/K2_Lab_Power_Supply/powersupply_ckt_layout.pdf )

additional:
*digital panel amps (for input AC and output DC) and voltmeters,
*power transformer inrush soft start circuitry,
*probably ~90% or more of the referenced schematic elements.

Once again, I note that I have built the referred 0-50V and about 0-10A output current capability power supply 100% independently (since making of printed circuit board+100% build by only my hands), but to obtain a higher voltage, I feel that my theoretical knowledge leaves me in trouble, so I am asking for helpful guidance from the experts here.
I apologize if my request for help is stupid, I also apologize for the typos. I don't write english in my native.
Thanks for any help!

Found this circuit in an old Philips publication. It was intended as an amplifier stage for an audio oscillator but it looks like it could be used as the basis of a reasonably good audio amplifier. Cascoded long tailed pair input stage with current source in the cathode circuit. Second stage has an unused anode just begging to be used as a push pull source. Distortion figures look pretty good.

I cant find a good repair shop and "I am thinking of trying to fix" my 2 amps that are starting to crackle and pop even with no load on them.
I am ok/good at repairing simple electronics, real good at soldering, measuring with instructional Guidant's.

POA-2400 2ch
POA-6600a monoblock

On the 6600a I first was thinking it was CAPs going. So I did a lookup for replacements and couldn't find exact replacements for the big 10,000uf ones but I found some close / hopefully better replacements, So I think..
Here is the Info for others-hope it helps..
Original was Nippon chemi-con: 90volt 10,000uf 85deg temp, tolerance? Rated ripple (Arms) ? 50.8x82.55mm or 2inchx3.25inch.
New Cap Nichicon Grade TYPE-2: 100volt 10,000uf 85deg temp, Tolerance: 20% Rated ripple (Arms) = 6.90 50 × 100mm or 1.95x3.9inch Part # LKG2A103MKZ

But then I wondered could it be the IC or other chips but upon looking them up I cant find those exact ones or equal replacements.
Toshiba TLB521-1-BL / Optically Coupled Isolators, I can find TLB521-GB and other variances but the BL seems to have special ELECTRICAL CHARACTERISTICS 200min%-600max% and I cant find it anywhere.
Mitsubishi M5238P / DUAL LOW NOISE JFET INPUT OPERATIONAL AMPLIFIERS 8 PIN DIP, I can find it but not sure if they are legit suppliers.
Mitsubishi M5238P or NJM-082DT/BD JRC or NJM-2068DA JRC, I haven't tried to lookup yet
Hitachi HD14001BP / Quadruple 2 Input NOR GATE, I haven't tried to lookup yet..

• If you think I really need a scope to do this and if you know of a inexpensive one, please suggest. just for amp repair.
• Any idea's a good source to find chips with exact same spec. without hrs/days of searching? no eBay or Alibaba ect..
• Any idea's how to find exact problem. I have multimeters but don't have an oscilloscope.

Thanks!

We are running a small outdoor festival with a 6x4 m stage. Since the area is surrounded by walls from three sides, a relatively low power PA is sufficient. In the four years, the sound guys had the following:

1. KV2 top + sub (looked like bandpass), all active. One of the subs burned during the show, a single one was actually still sufficient

2. HK Audio Actor system with 1 sub - this was a bit on the edge, but still passable.

The sound guy using these came in a Mitsubishi Pajero with 4 active monitors.

3. A homemade PA system, biamped - bass and tops had a separate amp. This one needed to be on a small trailer - but I liked especially the bass boxes - simple bass reflex with Celestion FTR15-4080FD - a single pair was sufficient even with the non-ideal placement (one on each side more or less). Last year it was with two other subs, but it worked this year really well without them.

This lead me to an idea - today, amp power is relatively cheap and class D amps are not too heavy. What would it take to build a relatively compact, light (neodymium speakers) and not too expensive three way system with great performance? The contitions are the main PA must fit into a larger car or a small trailer and all the boxes must be as light as possible to be easily handled by one man. Any inspiration from your systems would be appreciated🙂

Recently, these boxes were linked in a thread here: Soundgear - Speakers - Amplifiers - DSP - these with a sub would probably work if the dispersion was not as narrow. Also, these would be too complicated to build.

I would think a 15" BR sub, with a 12"(15") + 2" top could be great.

For an even more compact solution, if the sub could play up to ca 400 Hz, the RCF H6000 8" horn + a 1" driver could maybe work as well - a sort of passive RCF 6001 split into two boxes with the low part playing a bit lower.

Or are my ideas completely off the limits?

I 've got some huge bass and midbass horns, but these need a large van to transport - but I would be willing to do a bit of compromise between the efficiency and sound quality and smaller dimensions - for smaller venues like the one described.

I am in the process of building an active 4 way.

Below and above what frequencies does the human ear become less sensitive to lobing?

In a 4 way, it is very difficult to mate the upper mid driver and the tweeter.

If lobing is unavoidable, then perhaps making it symmetrical (MTM) is preferable.

Alternatively, can we move the MT crossover point higher and use a narrow dispersion tweeter instead. This would make the lobing worse, but is there a critical frequency beyond which lobing is not audible any more.

Same Q for the bass -midbass crossover point.

FS: Few different items - C relays, Meters, Caps, Cam, Cable

Up for sale few different items, selling of which separately has no big sense considering single way to accept payment and price of each item/shipping, but which can be combined to each other to increase sense of deal, or with adding to other our more expensive items how :


So, items :

1. Meters

Meters Marion, 2 inch, hermetized, glass soldered to body (but can be desolded with skill).
2pcs - 100mA, 500mA - red overlay - 20,-eur
2pcs - 30 microamperes, 50 microamperes - black overlay - 20,-eur

Meters - Google Drive
----

----
2. Mintron 1/3 CCD cam, chip board.
Model: Mintron MTV-53KS80AHP, PAL version
Sensor: 1/3 CCD
CCD total pixels : 798х584
Min illumination : 0.8LUX/F1.2/5600K
Resolution : 470TVL, 580TVL enhanced
WB range 3200-10K
S/N ratio : 52dBmin/60dB typ
Electronic shutter : AES 1/60-1/120,000sec, FIX 1/60-1/10000
Operation temp : -20C +50C
Power Supply : 12VDC 150mA
Board size 42x42, tallnes 40 with optic

Also possible additional optics.

https://drive.google.com/drive/folders/1SsurzsJuXb8Vtmmz9wOS9nuiXolO_OnU?usp=sharinghttp://

2 pcs on stock, 40,-eur each cam
----


3. Elelctrolytical caps 80-100uf, 400uf, 500uf & 50-450VDC, mostly for tube devices.

General Electric caps, Mallory, Planet Lyticap, Sprague, Cornel Dubilier, AeroVox.
Set 1 - 8pcs - 25,-eur
Set 2 - 9pcs- 20,-eur SOLD XXX
Set 3 - 14pcs - 20,-eur SOLD XXX

See more detail pics and specs in archive >> :
https://drive.google.com/drive/folders/1upKhx2wZvHdH9QbqPIgjw1X_8yfh-sYk?usp=sharing
----

4. High voltage mica caps, USA vintage, 1-5kV, AeroVox, Sprague, Sangamo, Cornel Dubilier
https://drive.google.com/drive/folders/1R5QWZqao1L086c-G1JgnnYNoVNKvjgo5?usp=sharing

21pcs - 15,-eur

----

89,-eur
FREE shipping across EU/UK

Up for sale last vintage attenuator, USA made.
Other 8pcs were sold.

So:

Daven Shalco 520-5C1, 600 Ohm, 0.75W, dual channel, 21 step (incl 0dB)

Attenuation :
- 10dB/0.5db - 1pc

Big, Dia - 65mm, Lenght - 100mm (with no shaft), fastening with two bolts through scale.

Questions, info, more pics on request, any time.

Pieces will be packed carefully with international tracking across all distance.

Sending from Ukraine. PayPal possible, in some way.

FREE shipping across EU/UK


---
See also other our items:

FS: Set of 4+ excellent UTC transformers A-22, Northern Electric

FS: Few different items - Meters, Caps, Cam, Cable

I tried this post in the audio asylum. Got lots of agreement, but not specific plans. Maybe you DIY'ers have tried this and would be willing to share your ideas. I have tried several subwoofers to give more "punch" to my Maggie 20.1 system, but all have been of the closed box design--ported or sealed--and I could never get them to integrate well with my planars. Didn't really get more "punch" either. Right now, I am biamping my Maggies and the sound I am getting now is the best yet. But I would STILL LIKE A MORE DYNAMIC BASS. So, maybe I'm going at it wrong. How about an OB design with six 8" woofers per side to be placed alongside the Maggies. This would make the Maggies act like "wings," thus extending the bass. Also, an OB array should mimic the way the planars launch a wave front, possiby lending more coherence to the overall sound. Has anyone done this? Can you recommend drivers, xover, etc. ?
Thanks,
Chuck

it's been a long time i have not DIY anything in my audio chain, this covid and WFH make me lazy.

anyway just started with 3way bass reflex with drivers used : Dynaudio 24W100, MW152 and Satori TW29RN

I wanted full Dyn drivers, already got MD100 but compared to Satori it's different class. so back to Satori, my candidate someday maybe MD130 but can't find it yet

mid + tw will be passive xo which i hope can get simple xo without too much parts used.
while woofer + mid will use minidsp 2x4HD

woofer will be in bass reflex around 40L volume, while mid will have 4L.

this will be my 1st build with measurement using UMIK-1, for sure I'll need all of your suggestions later once i finished the woodworking especially on how to analyze measurement results

I measured the inductance of different inductors and found a rather high dependence on frequency in some cases. With my LCR bridge I can only measure @ 1kHz and 10 kHz but from my woofers response I can see that it extrapolates to lower frequencies as well. Especially one EI-cored foil indcutor stood out with a delta of 20% difference between 1 and 10kHz.

From what I have read: In case of cored inductors this has mostly to do with the frequency dependend magnetic susceptibility of the core material used. With air inductors some claim skin effect and or parasitic capacitance.

From the limited data I have gathered it seems the nominal inductance manufacturers print on their cored inductors are rather a ballpark figure as neither the frequency the measurement was taken at nor any non-linearities are usually specified. In practical terms this would mean that I have to change windings or the core gap to get the desired result especially with inductors that use a lot of core material.


Is this a known fact or am I totally wrong somehow?
Many thanks for your comments .
Ozo

Good evening. I finally have my 807 PP class A2 monoblocks operational. They started out as an attempt to build something useful from a pair of old Philips EL6400 PA amps, several iterations later they have evolved into something completely different using only the same mains and output transformers.
The circuit is somewhat inspired by Altec 1570, where the output tubes are driven by a pair of cathode followers loaded by a center tapped choke. Where Altec used a two 6W6s to push a pair of 811s, I got away with using the smaller pentode sections of ECL84/6DX8 to drive my 807 deep into class A2. The triode sections (~1/2 12AT7) are used as an LTP input stage.
Please ignore the abscense of grid stoppers, protection diodes and even screen grids in the conceptual schematic, they're all there IRL. And while you're at it, please have mercy with my photography skills too... And yeah, I'll definitely get insulated top caps.

At the moment I'm running these amps with zero NFB (the output tubes are triode wired) with an open loop gain of x10, but I feel I could trade some gain against higher DF.
GNFB from the output to the unused input of the LTP would be the most obvious method, but perhaps we can come up with something more exiting?
Some kind of symmetrical feedback either from the 807 plates or the unused UL (50%) taps would be nice, though I'm aware that "Schade" feedback supposedly don't work well with triode input stages.
Perhaps changing the input stages to cascoded LTPs would make them more suitable for local feedback?

Hi there,
I've been a member in this forum for a while, but have not posted anything so far until now. So it's a bit of introducing myself as well, I guess.

Doing this with a friend of mine, we now have a prototype of an open baffle line array up and going. Inspired by speakers like Adyton's Imagic Imagic 2.0 Loudspeakers , Steinway-Lyngdorfs Concertos, and many great builds going on here (Wesayso's array, Halair's, loads of OB's: StigErik, Scorpion, The Fin etc) the goal was set to try to make an active OB line array. A sort of "Dipole Imagic".

Enough said, here are the specs/goal for the final set up:
3-way active Line array
OB/Dipole
16 Vifa TC9 (Vifa9 BN 119/8) in each speaker
Mundorf AMT dipole tweeter
OB/Ripole sub (2x12" each)
2 x Hypex as2.100d
Rough estimation of cross overs: Vifas running down to about 100-200Hz up to 4000Hz where comb filtering will start (These are 84mm cc). If the combing can be eq'ed out (which it might not?) we can leave them as they are maybe...?

So far we have a prototype running with the Vifa's, having the aim to set the midrange first.


I've been studying Jim Griffin's and M J King's white paper's, some Linkwitz and other ob sites (+loads of forum threads...), so I'm a bit aware what we're up aginst! We did a 180x11cm baffle to mount the Vifa's in with piano hinges on the sides, then put different baffle sizes and shapes to it and listened to how these affect this array quite differently. Anything from a angled back v-frame with 45cm wings, to the single naked mounting baffle have been tested. (Please ask if you are interested i some special shape.) According to both Edge and my ears the versions with any kind of angles baffle shapes (more like a pyramid) always got the best result. Finally we have set for a flat baffle, having the array off center and angle the baffle side shapes:

Having the array centered or having completely rectangular baffles gave a more "dead" sound presentation (if I may be subjective here;-)) and didn't improve soundstaging. I should also mention that the array is power tapered in a 2/4/4/6 way (but will probably be 2/3/3/4/4 because I think it's too much now).
So please now, have a look at these measurements. Made outdoors, 1,2,3 meters resp. with REW and UMIK-1.

All distances:

3m complete:

3m zoom in:

Thing is, while there is no problem to get some bass in the array despite it's an OB (according to our xover goal), the midrange where the array should excel is very strange. Some voices, double bass, flutes, some westcoast jazz can sound quite good, while strings, acoustic piano is cathastrophy: hollow, "distorted", sharp, i.e. no body to it. So far my limited knowledge of EQ/filters cannot solve this. I've tried briefly but this tendency remains whatsoever.

Now I'm finally coming to the point where are now, because all this tapering and assymetric shapes in an OB maybe are the cause of my current problems? Or shouldn't it help? Are there too many therories competeing in the same speaker?
Please help, because probably I'm missing out of something fundamental here!


Any input appreciated!

Best wishes,
Anders

PS Hope the image upload worked!

Octal sockets are very confusing to me. Using Eagle Cad with a few custom lib's My first socket was a Belton in the large footprint chassis mount, had a PCB made worked OK. Then I wanted a more generic Octal like the cheap Chinese and eBay ones for PCB mount. I grabbed a footprint from a recommended lib on this forum. Well the footprint did not match the socket, the socket was from Amazon and seemed to the "norm" at this point I didn't know whether to look for a different socket to fit, or have the PCB redone to use the sockets I have. So I found a third footprint of Octal s that looks like it will fin my PCB. I guess my question is How the heck many different sockets are there for Octal s and what is considered the norm for PC mount?

Thanks for reading this.

Alan

I just acquired a Hafler DH-101 (serial number 1020167) and am about to launch into a comprehensive refurbishment of the electronic components. I have no interest in doing any of the much discussed mods, nor do I want to make any alterations to the original design. I plan to change capacitor and resistor construction as is feasible (film capacitors and metal film resistors), and likely will replace the rear RCA jacks. I have verified that this unit has the DH-106 upgrade in place. However, I'm confused about two things I see on the P-4 board.

First, according to the Component Values list in the manual, C1 is a 220pF 1000V Disc capacitor. However, in the location on the actual P-4 where the layout diagram shows C1, neither channel has the capacitor present. It doesn't look like the capacitors were removed from these locations but rather there were never any capacitors in these locations to begin with. Could this be a later production run modification?

Second, in locations C2 and C11, the Component Value list and the P-4 layout diagram shows a single 10uF 3V Tantalum capacitor in these locations. However, the actual board has two 10uF Tantalum capacitors installed in series (+ to +) apparently to create a virtual non-polar Tantalum capacitor. My question is, if I were to replace these with film capacitors, what should the capacitance be? The normal formula for capacitors in series would yield 5uF for this arrangement. Or because this is a "non-polar" Tantalum, is the capacitance calculated differently? I would prefer to use is single film capacitor in these locations, but will do a direct replacement of the Tantalums with electrolytics if necessary.

Thank you for any assistance anyone can provide on these questions.

Dear Friends,

I'm designing a simple AK4493S DAC and I'm struggling to understand why the analog filter in datasheet uses not symmetrical values for both phases. See the image attached.


Can someone explain to me how this filter works? Also the second set of filtering elements seem to be unusual with capacitors placement and two resistors per phase.

If there are books I can buy to learn more about analogue filters like that can you link them? I would be in your debt.

Best,
Somek

Hi all

Many years ago I had a pair of Triangle Magellan Cello SW2 before personal circumstances forced sale. I’d now like to try build my own speakers to try better the Cellos. I do recall favouring the sound of the Cellos, particularly vocals.

Any publicly available designs that may replicate or better the Cellos?

I am very comfortable with carpentry work by the way.

Thanks
P.

I just built an ACP+ tonight, and hooked it up to my ACA and DIY MarkAudio fullrangers. Compared to the previous pre amp, and the sound straight from source (my computer), there is a very noticeable lack of bass. Like the low notes are inaudible.

However, when I plug in headphones (66ohm Audio-Technicas), the bass comes back.

Anyone have any idea about what I may have done wrong? I checked the resistors in the pre out path, I am pretty sure they are the correct spec.

Had to restore a Revox A700 tape recorder and it needed also upgrade of this board, so I made few more for sale. For EU buyers - price is $90 including shipping if buy directly, for non-EU - better to buy it through eBay because it pays the import taxes and all is much easier - https://www.ebay.com/itm/185563616666 . It have pre-regulator for the opamp and all other is as in the service manual for PCB 1.067.421. Item is located in Sofia, Bulgaria

After a long hiatus (covid pandemic mostly to blame), my wife and I decided to go and watch the newly released “Death on the Nile” at the movie theatres in our local Mall. Unfortunately, it was not the great experience we hoped for.

I must make it clear that our bad experience was due to some personal reasons. First of all, the sound levels are way way too loud. So loud, it was actually difficult to follow most of the dialogue. Secondly, it looks like movies rely more and more on shock tactics and effects like sudden ear deafening bangs and slams. Totally over the top scenes and accompanied effects. Just watching the trailers of a few upcoming feature movies was overwhelming and exhausting. Thirdly, the only other person in the whole theater sat in the row behind us and seemed to have more pleasure in indulging in heaps of popcorn, chocolates and cooldrinks, rather than enjoying the movie. I’m not a popcorn fan, and why is everybody so obsessed with popcorn at the movies anyway? Fourthly, for the price of the two tickets I could have rather bought some Aleph J boards at the diyAudio store or snake-oil speaker cables. Yes, I am getting old, and I don’t do animation movies or 3D movies.

We did enjoy the actual movie though. Not the best murder mystery we have seen, but it was good enough. However, the whole experience would have been much more pleasant in my own home where I can play the sound over my own hifi. My setup at home is not even a HT setup, but I can now understand why people invest in HT. The movie theater sound was rather horrible compared to my speakers at home. I enjoy movie music much better at home. I can actually hear the dialogue much better at home. I can control the volume at home. I have access to great refreshments at home. I don’t have to put up with other people and their quirks at home.

So, my question is really – how do movie houses (as a business) still survive? Or, for how long will they still survive if you can have a much better experience at home?

as above.

I've searched the net to understand how it works all I can see "push-in connection" from their datasheet.

it seems suitable/ok for a stationary device an an audio device?

Thanks in advance.

Who can upload the schematic ?

Circuit design was made by Ken Ishiwata
http://www.dutchaudioclassics.nl/interview_with_ken_ishiwata/
and manufacturing of the PCB in Germany (Audionet)
AUDIONET - Scientific magic.

moer URLs:
https://s-media-cache-ak0.pinimg.com/originals/17/33/7c/17337c3eb08a848906e54bfd017aa2bd.jpg
https://c1.staticflickr.com/7/6024/5966807821_622407ea80_b.jpg

Looking for some 2Sc2291s G or H Hfe rating

Inherited these from my dad a few years ago and spent some time replacing the drivers and tweeters as they were knackered. (was told the drivers that were fitted at the time were Elac 8", but there were no markings and they weren't a matched pair anyway) The original tweeters were goodmans DT4 silk domes. I replaced the main drivers with a matched pair of KEF B200 SP1063A and the tweeters with a pair of Seas prestige H1280-06 22TFF tweeters. I reused the original crossovers that were there. The cabinets are 24L or 0.85cu.ft and ported with a 52x155mm port. Having read the specs on the kef drivers I've listened to them with the ports plugged. I have also tried unplugged too and found little difference. (although I've left them unplugged) Overall I find them quite pleasing to listen to, however I don't know if there are any improvements that I could make to them.

This is how they look now.


The crossover AFAIK is 1st order for the LF/midrange and 2nd order for the HF. The capacitor is 4.7uF 63V. I don't yet know the value of any of the other components. (I'd rather not have to dismantle them to find out)



I'm guessing a custom crossover for them might be better suited. If anyone can rough guess (or knows) the crossover component values can plot the response for me, that would be a great bonus.

Anyone with experience with the Troels Gravesens Ellipticor-3. A few years ago there was a thread about the Ellipticor-3, but it was a bit drowned in suggestions for all sorts of other speakers. I am interested in hearing experiences if you have built this speaker. I think it is exciting that Troels Gravesen has used a Sine-cap highpass filter for tweeter. It is quite unusual for Troels Gravesen, who is usually not afraid to use capacitors also on the rather expensive end. I watched a youtube Tech Talk 15 with Danny from GR Reseach. He had it in for an update for the XO as the owner was not really satisfied. Does anyone else have experience with the XO not working well or it can be thought that the owner just have looked at the chart and guessed at the values. I think that Troels Gravesen otherwise has a reputation for being a master at XO. Danny also says that cheap components have been used, something that Gravesen doesn't seem to have a reputation for either. The 2 of the coils are not only air coils but also of the Litz type which should be the level up from ordinary air coil.

From what I have seen, both Danny and Gravesen are extremely competent loudspeaker builders. As the Ellipticor tweeter is very effective, I have thought of using it in a construction once with a sine cap filter, which does require a lot resistance in the signal so that the impedance does not go all the way down. Hope there are some more experiences 2 years ago
where someone else asked about it. But it's not a cheap kit, even if you don't add capasitors in the XO as the drivers are some of the most expensive on the market.

Hope we have kept the thread on Ellipticor-3 🙂

One pair of verry good verry known german rca cable. 2 x 0.5m with original conectors in good condition. 40 euro plus 7,90 euro shipping inside EU.

Looking for the right part number for smd transistor "BR". Pics attached.

Thanks in advance.

"Why are you applying for this job again? Are you sure you want it?"

A while back I built MoFos. The idea of using the primaries of salvaged power transformers from microwave ovens as chokes came up. I briefly tested one in my MoFos, heard that it worked, and moved on. But I had collected a few of these and I was intrigued with the idea of winding my own choke on the laminations from one, so I cut one open with an angle grinder, hacked together a winding apparatus, and wound a coil. As I had no bobbin, I couldn't get my wound coil to fit back on the E-laminations and so I gave up.

Learning about current-source amplifiers as a match for full range drivers led me to Papa's exploration of the Jean Hiraga Nemesis design, first as the Arch Nemesis and later the SIT Nemesis, which paradoxically and perhaps unnecessarily pairs an output transformer with a FET. Lo and behold therein were specifications for a weird output transformer! One with a 64 ohm primary with an 8 ohm secondary, and a primary rated to 1.3A. How cool! Maybe I could make that!

I did some tiny maths. As Papa said it was a winding ratio of about 2.82:1, so I settled on 264 turns primary against 94 turns secondary, mostly as bass extension to 25Hz required about 0.4H of primary inductance based on a primary impedance of 64 ohms. A 50W capable primary at that impedance could mean 56.6V primary, that meant 3.67A on the secondary, hence 16ga secondaries and 20ga primaries. These windings would just about fit, haha, on the EI-125 laminations I salvaged from two MOTs, which were good by spec to at least 90VA at 60Hz. I then actually got brave and bothered Jack Eliano with this draft design, as he originally built Papa's OPTs and I admire him and have some of his PVA-2n's in a passive preamp, but he shared his final prototype design with me and it had different specs and anything I made with materials at hand would likely have inadequate dynamic range and bass extension. A dark art indeed! Since no one was responding to my E-I laminate purchase inquiries I decided to build my own trafo from my salvaged trash anyway.

I bought one of those cheap manual winding 'machines' & made a mount for it, as well as a mandril and some disc like adapters. I also found a pair of bobbins on ebay that would fit the laminates I had, and settled on a design that would wind half the primary, then a layer of grocery bag, then the secondary (counter-wound to the primary), another layer of grocery bag, then the second half of the primary. I opted to re-use the 16ga enameled wire from the first failed effort, kinks, scrapes and all, and bought a spool of 20ga for the primary. Set it up & started winding.

What a pain! But I got it done & strapped it together with a hose clamp with nothing gapping the E and I laminates. I measured the primary and secondary inductance, and it kinda made sense, maybe: Primary DCR = 2R1, inductance with open secondary = 213mH, inductance with shorted secondary = 0.557mH. Secondary DCR = 0R3, inductance with open primary = 26.7mH, inductance with shorted primary = 0.059mH. Maybe sloppy, but a trafo perhaps.

I didn't know how else to test it, so I dead-bugged the Figure 6 circuit of the Arch Nemesis paper using an IRFP240 pulled from a MoFo and some power resistors I had laying around, and set the gate bias using a little DC buck converter. I settled on 50R for R2, 12R for R3, 1R for R1, and gate bias of about 5V. At 45V of V+ it drew about 0.94A across R1.

To my immense surprise, the darn thing played actual music. Tinny and thin at first, but full and kinda brassy and warm later, actually a surprisingly familiar tone to me from the PVA-2n preamp and MoFo experiences. To my chagrin as I played with the gate bias and V+ the music got thin and then disappeared completely. Pressing on the OPT brought it back temporarily only for it to fade, leading me to wonder if the core was saturating due to inadequate gapping. I dismantled the trafo, put a piece of plastic insulation between the E and I laminates, powered it up and it played music again! Very cool. Can't tell you how pleased I am that my junk salvaged first-time trafo actually made music.

Will have to decide how to permanently gap and mount the laminates as the fading and tinnyness is annoying, and whether I should wind a second core to make a mate for this one. I could even use SITs! 😛

I have for sale 5 modules of LM3886x3 amplifiers. They’re roughly 150W on 8 ohms per module.

Assembled those some years ago for a 5 channel HT system. Since I upgraded to Atmos 7.4.2 setup, I no longer need them. I bought a dedicated multichannel amplifier since I needed the gain to be the same on all modules.

How about $USD + shipping for the lot?

I'm working on a pair of ESS AMT1. One cap is a different value in each pair of speakers. It looks like there are a few versions of this crossover and I'm not sure which caps are original so I'm having trouble figuring out what the values are supposed to be.
Each speaker has two 100uf caps in series. So this position is 50uf.
The other cap is 20uf in one speaker and 16 in the other.

A couple caps are visibly shot so a recap is mandatory.

I'm finding there are many different versions of this crossover. Even a couple different iterations of this layout.
Some have a 20uF cap for the woofer, some have a 55uF cap. With a 20uF cap, the woofer crossover point is 639Hz and the tweeter crossover point is 726Hz.
With a 55uf cap the crossover point is 385Hz. Seems the crossover point the 20uF cap gives makes the most sense?

The value of the inductors are marked slightly differently than on the schematic. One is marked 3.8mH and one 2.3mH. I don't see a marking on the third but it isn't part of the same filter stages the caps are.

Anyone have ideas or additional information? Any other crossover designs for these speakers that might be better?

I'm also interested in hearing about what types of caps people have used and the results from those.

Hi,I'm a new member and looking for advice.
My previous system now defunct was a marantz cd-67se into a nad 5020 and mission 773e speakers.
Sadly the cd player despite repeated fixes gave up the ghost a while ago and the nad amp badly needs recapping.

So for some time I've been listening on a rubbish bt player and hankering after something decent but new and hopefully not too expensive.
Then last night one of my best friends is moving and says he'll gift me his mission 770 freedom speakers.
A step up in quality over the 773e's.
So I started looking for a new amp and streamer and found the allo.com boss 2 player and the volt d+ amp.and thought that's absolutely perfect and not too pricey either

Then of course I realise it's out of stock and for all I know discontinued.
Can anyone recommend an equivalent for the boss 2 player? And or volt d+ amp? In roughly the same price point please.
I'm a total newbie to all this streaming technology. Being 55 and coming from the world of nuts and bolts.
So any help would be greatly appreciated.
I'm in the UK too. England
Thankyou.

Available in a week or two, my Jay's Audio CDt2 MK3 CD transport (as new, less than a month old at the time of this posting) and not at its best yet, Jay's suggest a min of 100 hours burn in.

Comes with all original packaging and accessories. The remainder of the warrantee is transferable to the new owner, 11 months. This is a stunning sounding transport which has had many rave reviews, just google it.







To answer the question 'why are you selling if its that good!!

yes, I bought the CDt3 Mk3.

£1950 ONO + shipping at cost and can be auditioned (Hampshire UK) by arrangement.

Hello all, first post!
A couple of months ago, I went looking for a 2A3 SET kit to replace my aging Paramours. I looked at all the usual suspects: Stereomour, Monamour, Elekit, etc. I didn't want to go 300b, but I did look at AudioNote kit also.
Well Analog Ethos was mentioned a few times on other forums but besides that I couldn't find any info on them other than on the website. Kind of sketchy I thought.
The Legendarium kit however, was exactly what I wanted. Sort of.
I wanted a stereo 2A3 amplifier, not integrated, mainly because I wanted to keep my preamp in the chain.
So a couple of emails later, I plunged!

Kit was delivered two weeks later, the lead time stated on the website.
All the parts are neatly packed, double boxed with lots of foam.



Everything is individually bagged. No mistakes (except by me!).
Parts are all top notch, Hammond, Edcor, Vishay, Clarity, Alps, etc. Not much room for upgrades although I did purchase some gold pin Belton tube sockets (super tight!) and coupling caps.



Instruction manual is pretty hefty! Also includes a section on how tubes work. What's nice about it is that it just doesn't say to solder this to that, but it also explains some of the why and what you are doing. About 90 pages!
Chassis is very nice and comes finished as opposed to say, Bottlehead. Three color choices and the exterior wood is filled and sanded for a smooth no grain look.
Top plate is also finished well, thick and no burrs on in the holes. Very nice.
Here I am about to hang the caps:



One of the things I wanted was point to point wiring; least amount of stuff in the signal path and all that. The only thing about the Legendarium is the volume pot. I may bypass that later, or maybe just run my phono stage direct and lose the preamp.





I did change out the coupling caps to Duelunds:



The Legendarium sounds great! Pretty much walks all over my old Paramours!
It comes stock with Electro Harmonix power tubes, EH drivers, and a JJ 5U4GB rectifier. I rolled them all out and run all NOS RCAs, which really make this amp sing!

As I mentioned earlier, I couldn't find any info on this kit, so I hope this post helps folks looking for more info. Perry, the owner is super nice and answers emails quickly! I did have a slight user error problem and he was right there to help. Also interesting is that the construction manual is available for downloading so you can see what you are getting into. Nothing to hide here!
Analog Ethos also has a few other kits and all of them are also available assembled.
I highly recommend! Easy to build and it sounds awesome!

Hi Guys,
I have a pair of AST-S1 speakers I bought from ebay and the previuos owner did a dodgy repair on the rubber surrounds and shagged them 🙁

Does anyone have or know where to get a couple of replacement woofers?

I am open to refoaming them however the kits I have bought to date have been the wrong size (up to 3mm out of spec.....).

Cheers
Matthew

You probably know that Speaker Workshop has been open source for a while. Speaker Workshop | Free Audio & Video software downloads at SourceForge.net .
There hasn't been much interest in modifying the source code, probably because there isn't much to fix or change. It works good.
But what I'd atleast like to see happen is the source be compiled into a more modern (Win7, Multi core) platform. And for a Mac platform as well.

Anyone here who knows and is willing to just recompile the source into an executable for a current platform and put it out there for download ?

Anybody planning on buying a pair to try out? I have not the test equipment anymore to prove them but would be interested in picking up a set. Maybe I could grab a pair and send them to someone willing to run them through the ringer?

Tube Amp Parts - Output Transformers - AnTek Products Corp

We just put an offer on a house (which was accepted!!!) So once we find out how everything goes with escrow and our out of pocket expenses I may want to grab a set.

I'm particularly interested in the 5k, 15 watt unit. They are 1db down at 10khz, 3db down at 20khz. Seems plenty workable. Maybe even running 4ohms on the 8ohm tap, for 2.5k would give even better response? As it is they might be a good fit for a pair of EL86 or parallel pair of 6V6 triode connected.

Pharoah Sanders died peacefully in Los Angeles at the age of 81.
He was a master of jazz.

R.I.P.

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I am looking for a recommendation on a good PSU build for my Hifiberry Dac I will be using as a Roon bridge device. In the past, I used the IFI iPower Wall wart and it sounded fine, but wanted to experiment with a new linear power supply device I could build or buy from DIYAUDIO.

A couple ideas I had:

• Silent Switcher V3
• Super Regulated Power supply (I have the boards already and can use one)
• Jason Keutemann's Capmx board (I have one of these fully stuffed)

Or I can buy one fully built online, but what is the fun in that?! Any help is appreciated.

I know this has been discussed before, but of course it never quite fits your own situation 😕

I recently scored a really nice pair of Videoton Minimax II's (for those who don't know them a budget Hungarian mini speaker with 5" bass unit and 4" cone tweeter that were hugely popular in the early/mid 70's) for some reason they were really quite magical, way greater then the sum of their parts.

This pair though the rubber surrounds on the bass units has rather dried and has some cracking, not bad, I've seen way worse but I'd like to stop or at least slow any further deterioration. Apparently the amount of degradation in these particular speakers was due to the exact amount of sulphur present in the rubber used in that batch..

I was thinking of maybe coating the surround with Copydex (a flexible water based latex rubber glue) I've heard of it used for rubber seals etc to 'repair' the cracking and/or maybe silicone grease, the type used by plumbers as a lubricant to rehydrate as members seem to rate silicone quite highly, maybe after a copydex application..

Any thoughts anyone? Has anyone tried anything similar?

as above. (preferably a design where I can buy the PCB or one with Gerber files)

Thanks a lot. 👍

Edit: I'm not really knowledgeable with the balanced/differential configuration but I mean a preamp that has +/- left/right input and same for output.

I'm one of those dudes that's a 'quality over quantity' guy. For that reason, I always get annoyed at live gigs where the PA's can smash 45Hz or even 35Hz (in the better venues), but the bass drops just fall flat anywhere below that and at 25Hz, it's just flab. I'm interested in designing and small bookshelf unit (>= 0.5ft^3) that can hit flat to 25Hz with an F3 in the low 20's and F10 in the teens. It's obviously not gonna go super loud and I'll need a hefty amp to push it and I'm fine with that. I just want a solid set of office speakers that can actually play everything on the recordings without having to drag in a massive overkill sub. About the closest thing I can find is the TangBand W5-1138SMF, but even that tapers off around 30Hz in a ported unit. It'll do, I guess, but if there's a similar size (5 1/4") or smaller that can go lower in a small enclosure, I'm all ears!