Hello maybe someone know if there is a motherboard with new N intel CPU like N305 in Europe? I would like to avoid atx psu implementation … 1x PCI express also needed

Hi folks, what are some typical thicknesses of ribbon material? Do DIYers and commercial products mostly use the same thickness? Thanks.

Let’s say you’re building a passive preamp, whether it be a typical attenuator or maybe an autoformer, and you wanted two inputs, one for a cd player and a tuner - and one output for a power amp. Really basic, right?

Keeping it really basic, let’s say you don’t want to include a source selector switch. You could have one pair of input jacks on the preamp and plug in the CDP interconnects when listening to cd’s, and unplug those and plug in the tuner’s interconnects when listening to the tuner. Or just have one pair of interconnects and swap one end back and forth between sources, while keeping the other end permanently connected to the preamp. Kinda of a hassle, but I’m sure there are some that do this.

Are there other ways to handle the two sources without the use of a selector switch? What about having two pairs of input jacks (one for each source) and have them both wired to the volume pot? Since you would be listening to one source at a time, would the fact that the other input jack being wired to the volume pot (with no signal input of course) have any detrimental effects? Would there be any capacitance issues?

Happy to join the DIY community here to learn and share some of my experiences. I have been doing DIY audio for a while, but have been only reading the forum without posting myself. I am interested in valve amplifiers and loudspeakers.

Just saw this new amp IC being used in the SMSL SA300. The specs look impressive. 45uV noise with audio source off. 0.004% THD at higher power (not sure what power but not max). Max power in the usual 40w range for 24v supplies. Built in I2C serial data bus for DSP programming and basic controls.



Features from website:

Summary of Features

Multi-level switching technology with 3-level and 5-level modulation
2×80W peak output power (26V PVDD, RL = 4Ω, 10% THD+N level)
Supply voltages: +4V to +26V (PVDD) and +5V (A/DVDD)
Suitable for 2.0, 2.1, 4.0, 1.0 output stage configurations
4th order feedback error control
<160mW Idle power dissipation (26V PVDD, all channels switching)
>80% efficiency at 2W power (1kHz sine, 8Ω)
>91% efficiency at full Power (1kHz sine, 8Ω)
Audio performance (PMP2): >110dB SNR (A-w, rel. to 1% THD+N power level)
45µV output integrated noise (A-w)
0.004% THD+N at high output levels
I2C control (four selectable addresses)
Built-in protection: under-voltage-lockout, over-temperature warning/error, short-circuit/overload protection, power stage pin-to-pin short-circuit, error-reporting through serial interface (I2C), DC protection

Click to expand...

MA12070 - Infineon Technologies

https://www.infineon.com/dgdl/Infin...N.pdf?fileId=5546d46264a8de7e0164b750002861a5

Uses the so-called Multilevel Class D topology for the highest power efficiency, greater than traditional Class D - whitepaper:
https://www.infineon.com/dgdl/Infin...N.pdf?fileId=5546d462696dbf120169b4f8f7524db9

Applications:
https://www.infineon.com/dgdl/Infin...N.pdf?fileId=5546d462677d0f460167bba4f4e81abd

The SMSL SA300 which has got to be the highest feature packed per dollar DAC/amp I have seen.

If anyone has experience with this new chip please share. Getting the SA300 is less expensive than getting the Eval board from Infineon.

Is this the new “TPA3116 Juggernaut” of the 2020 decade?

Hey all. Just wondering if I can drive Martin Logan panels with Acoustat Direct Drive Servo Charge OTL amps? TIA

Reading about @perrymarshall ’s Bitches Brew and other OB creations is an inspirational experience.
I already own some drivers etc that would could be used for a Bitches Brew inspired speaker. I have 4 x 18” woofers that have a sensitivity of 95db, so I’m thinking 2 per side. I also own a pair of ES 1200 biradial horns, so rather than use a coax for the mid + tweeter, I’m thinking this horn fitted with a 1” throat CD plus a suitable mid range driver. So I’m looking for suggestions for the mid range. It needs to be at least 98db sensitivity, be usable over say 150hz to 1500hz and to avoid beaming problems probably needs to be no bigger than 10”. All suggestions gratefully received.

Hi,

I have schematic of Krell KSA 50 - it is great amplifier, but I need pcb for it. Maybe someone can project this. I'll send circuit on email.

braa@poczta.onet.pl

This is a group buy for the combined turntable tachometer with motor speed controller that uses the feedback from the optical sensor to keep the speed locked at 33.33 or 45 rpm. The control loop uses PID control. You can just use the board as a drop in-replacement for the Linn Valhalla board without the sensor and OLED display if you wish to solve the heat and unreliability problems of the Valhalla and just get electronic speed switching. Works fine with other turntables that use compatible synchronous motors.

The full thread discussing the development is here:
Digital Tachometer for record player (LCD display)
Features:

• Electronic switching between 33.33 rpm and 45 rpm (no more pulleys)
• Highly accurate sine wave frequency synthesis generated for 50Hz or 67.5Hz controlled to 0.001 Hz
• Class A motor drive circuitry.
• Optional optical platter feedback sensor to lock platter rotation at exactly the right speed. This runs a PID controller loop reach maximum speed quickly then keeps rotation speed locked rock solid.
• Control over motor parameters such as frequencies, phase angle, voltage amplitude via a USB serial interface. Adjusting these values enables smoothest motor operation with minimum motor noise and vibration. Values may be written to EEPROM once optimum setup achieved.
• OLED display to indicate exact platter rotation speed and WOW
• Fits on original Linn Valhalla mounting
• Can connect to original Linn power switches.
• Speed change controlled by holding power switch for three seconds
• Less heat generated than original Valhalla due to redesigned PSU section (no more burned out resistors).
• May be used for other turntables that use a two phase synchronous motor such as Airpax, Premotec, Philips e.g. Rega, Linn, Manticore, Pro-Ject etc.
• Can be housed in a separate box.
• Uses standard commonly available low cost parts such as Arduino, AD1933 DDS generators, common transistors.

There are three options:

1) Bare PCB and Pre Programmed Arduino Nano 18.00 GBP
2) Full kit of parts as per attached BOM in above thread 58.00 GBP
3) Fully assembled and tested board 98.00 GBP

a) If you want the optional FFC / FPC RA header so you can use a Linn flexible circuit switch (e.g. if fitting inside a Linn LP12 replacing a Valhalla) then that's 1.00 GBP extra.
b) Recommended round momentary push switch/LED to fit OLED enclosure (see below). £4.50

Options 2 & 3 are complete with all parts (I2C 128x32 OLED display, DDS generator PCB's, Arduino, IR detector, passives, semiconductors, heatsinks. terminal blocks etc.). All you need to add is a power switch (momentary action), indication LED and external enclosure for board (if not fitting inside TT). You will get a 3D printed box for OLED & Speed sensor. You can also use this box to mount a stop/start/speed change switch.

If you want shipping outside of UK please contact me with your address and I will work out how much extra it will be. Some examples of tracked pricing are Europe £9.35 USA £10.55 GBP

This kit contains a SMPS that is not isolated from the mains supply (similar to Linn Valhalla board). I recommend you build and test with an isolation transformer/step down transformer (100 - 240v @ 120mA) for safety of you and your test equipment. You must be confident and competent working with voltages 90V - 320V.

The above being said, the kit is straightforward to build and I will provide full comprehensive instructions on safety procedures, modular build and testing plus actual setup with your turntable. There are some SMD resistors to solder on the underside of the board. The most difficult part is tuning the PID parameters via serial interface/tuning application but some examples are supplied.

As a reminder these boards are designed to work with 2 phase synchronous motors 50Hz/60Hz that work off 6V - 110V RMS (160v p2p) that have a current consumption of approximately 10mA per phase. AKA Premotec, Airpax, Philips motors as used in Linn, Rega, Manticore, Pro-Ject and other compatible turntables Two boards can be stacked to drive 3 or 4 phase motors. You may be able to use them on shaded pole motors by using a single phase as long as the voltage and current requirements match the board specifications above. I have not tested on anything other than synchronous motors. If your motor draws more current/voltage then you will need to use an off board supplementary amplifier as per Pyramid's SG4. This motor controller can be used as a source for the sine waves and to handle the tacho & feedback/control functions.

To proceed with the group buy please add your name to each of the categories below. Please copy and paste the whole list each time you post so the list contains running additions and I don’t have to go hunting through each thread.

1) Bare PCB and Pre Programmed Arduino Nano 18.00 GBP
2) Full kit of parts 58.00 GBP
3) Fully assembled and tested board 98.00 GBP
a) Linn Valhalla switch connector option 1.00 GBP
b) Momentary action switch/LED to fit OLED enclosure 4.50GBP

Hi all!

Hope I'm posting this in the right category.

I'm planning on adding a sub to my car's audio system, and would like to use the amp I currently have. There's 4 spare channels on it, that I would like to leverage instead of getting a new amp. Couple of snags with my plan so far:

• I don't know exactly how much power it can handle per channel. It's an older car, and despite my best efforts to obtain somewhat of a manual or datasheet on the amp, I'm coming up empty. That being said: I'm using 80 Watt (RMS) speakers in the rear, which seems to work without problems, so it's safe to say it can at least handle that.
• The sub I'm planning to use is rated at 250 Watt (RMS), and 4 Ohms nominal. The impedence is fine, as my current rear speakers are also 4 Ohm, but the 250W seems far off from the 80 I'm sure it can handle.

I've read into it a bit further, and ran into an article on Wikipedia about wiring amps in parallel & bridged mode. From what I understand, bridging an amp -theoretically- quadruples power handling, but also halves the impedence the amp 'sees'. Thus, briding two channels would give me the power I need to drive the sub, but would now make it impossible impedance-wise.

The wikipedia article then goes into the possibility of wiring 4 channels into a brdiged-parallel topology: "[...] when both configurations are combined on a set of four single-ended amplifiers, the power output is increased four-fold but the power dissipation of each constituent amplifier is not increased [...]"

Forgive my perhaps somewhat simplified imagery here, but what I understand from this, is that I can set the system up in the following manner to obtain ~320W @ 4Ohm, enough to drive the sub I have my eye on (see image). That being said, Wikipedia isn't all that great a source, and I can't seem to find anything/anyone else on the internet using this setup. This has me a bit worried, and I don't want to blow any equipment in attempting this.

So. Assuming the amp can actually be bridged, some questions pop to mind: Does this actually work? Would there be any drawbacks to wiring it this way?

Many thanks in advance!

Hi all,

So i have a question, i never usually listen to vynle but been asked to repair an NSM jukebox for someone.

Anyway today i finished recapping the amp and replacing dead transistors on one channel, full carriage rebuild and new stylus's.

That was the tip of the iceburg but you get the point its a proper rebuild.

Listening to records on it while testing, connected to modern speakers which i have heard before.

I am pretty sure that both spotify streams and cd should be much better than vynle but this thing sounds amazing i can hear every little detail in songs i have listened to on spotify and cd for years and im hearing new things i never noticed.

But why? Its suppost to be lower quality but this sounds much better to me.

I'm restoring a Yamaha M-70 and am in need of some NEC UPA74V & NEC UPA75V I thought perhaps I could substitute the 2SA1349 & 2SB3381 however the PD spec is 100 mW
Less. Thank you everyone for your time.

Terra Incognita - Passive 3-way with 8" woofer

With my latest project complete, I have been thinking about what to do next. I want to work with drivers I have not worked with before, in a speaker system that is different from my recent projects.

The new Dayton signature series is intriguing. They seem to offer a lot of performance at a bargain price.

The SB26STWGC is also an interesting driver. It incorporates a small waveguide into the excellent SB soft dome tweeter. I have been quite impressed with the SB26STAC soft dome (flat faced) used in another project. The small waveguide of this tweeter provides directivity control above 3k, so it would seem to be most useful when combined with a midrange driver in a 3-way system.

SB26STWGC-4 / Fabric - Sbacoustics

I am also interested in doing something I promised myself I would not do… a 3-way passive crossover. The fact it is challenging and possibly frustrating also makes it interesting.

Normally my projects use sealed box woofers with DSP to extend the bass response. A passive speaker, on the other hand, should stand on its own and have sufficient bass response without external EQ. I have never worked with a passive radiator before, and this kind of system is intriguing.

I also want to build something which is modest sized and relatively uncomplicated to build. At this point I was envisioning a gross cabinet volume of 35 to 40 liters. I considered several form factors, including a a large stand mount and a very wide thing cabinet, but in the end, a small tower shape is what I decided upon. This will be another open source fully-documented design (like the LCCAM-10.3), so I want it to be speaker which has a wide appeal to many people with a variety of needs and rooms.

So the initial concept is a 3-way speaker using the SB26STWGC tweeter, a Dayton signature woofer, a midrange to be determined later, a passive radiator, and a passive crossover, in a floor standing tower cabinet. It should be easy to build, and it should be easy to integrate into a room, both sonically and aesthetically.

j.
====== ======== ======== ======= ======
Update 11/07/2024



Now that the project is complete, here is an index to some of the significant milestones

Assessing the SB26STWGC tweeter
post-7692926 https://www.diyaudio.com/community/...ivers-a-new-3-way-project.413182/post-7692926
post-7696156 https://www.diyaudio.com/community/...ivers-a-new-3-way-project.413182/post-7696156

Midrange driver evaluations
post-7706642 https://www.diyaudio.com/community/...ivers-a-new-3-way-project.413182/post-7706642
post-7707383 https://www.diyaudio.com/community/...ivers-a-new-3-way-project.413182/post-7707383

Driver vertical spacing discussion
post-7701644 https://www.diyaudio.com/community/...ivers-a-new-3-way-project.413182/post-7701644
post-7709700 https://www.diyaudio.com/community/...ivers-a-new-3-way-project.413182/post-7709700

Selecting the Dayton RS225 woofer
post-7713405 https://www.diyaudio.com/community/...ivers-a-new-3-way-project.413182/post-7713405

Construction photos
post-7739426 https://www.diyaudio.com/community/...ivers-a-new-3-way-project.413182/post-7739426
post-7741685 https://www.diyaudio.com/community/...ivers-a-new-3-way-project.413182/post-7741685
post-7757392 https://www.diyaudio.com/community/...ivers-a-new-3-way-project.413182/post-7757392
post-7788145 https://www.diyaudio.com/community/...ivers-a-new-3-way-project.413182/post-7788145
post-7819159 https://www.diyaudio.com/community/...ivers-a-new-3-way-project.413182/post-7819159

Woofer and passive radiator tuning
post-7762790 https://www.diyaudio.com/community/...ivers-a-new-3-way-project.413182/post-7762790
post-7775930 https://www.diyaudio.com/community/...ivers-a-new-3-way-project.413182/post-7775930
post-7788318 https://www.diyaudio.com/community/...ivers-a-new-3-way-project.413182/post-7788318
post-7791525 https://www.diyaudio.com/community/...ivers-a-new-3-way-project.413182/post-7791525

Passive crossover network adds gain to woofer response
post-7763605 https://www.diyaudio.com/community/...ivers-a-new-3-way-project.413182/post-7763605

Midrange driver response different than prototype
post-7764410 https://www.diyaudio.com/community/...ivers-a-new-3-way-project.413182/post-7764410

Filter design and development
post-7765990 https://www.diyaudio.com/community/...ivers-a-new-3-way-project.413182/post-7765990
post-7773253 https://www.diyaudio.com/community/...ivers-a-new-3-way-project.413182/post-7773253
post-7793179 https://www.diyaudio.com/community/...ivers-a-new-3-way-project.413182/post-7793179

System level testing
post-7789237 https://www.diyaudio.com/community/...ivers-a-new-3-way-project.413182/post-7789237
post-7791924 https://www.diyaudio.com/community/...ivers-a-new-3-way-project.413182/post-7791924

Design Document
post-7835459 https://www.diyaudio.com/community/...ivers-a-new-3-way-project.413182/post-7835459

Salut!
I'm a long time lurker part time tinkerer.
Managed to build some preamps dac speakers and amps, I'm still build at some of them 10years later...

Hello, I live in Oklahoma - but I have traveled all over. My background has been Satellite Communications, Telecommunications, and I currently work for the FAA as electronic instructor. I have numerous interests, but one of them has been speaker building. I am currently rebuilding a new system using an active system - miniDSP Flex Eight with a multichannel amplifier. I am hoping to try and conjoin an open-baffle system with an infinite baffle subwoofer. I'm looking forward to future interactions with others.

This is a thread for the discussion of the design of class D amps, not discussion of kits or modifying existing amps.

Hello everyone.

I have a Rockford T10001bd PC-5445-B amplifier.

The amp has good gate drive on power supply.
The amp is making rail voltage.
The amp is making regulated voltage.
There are no shorted outputs.

The protect light is lit brightly, the output stage is not getting any rail voltage to the rail switchers or outputs.
There is 2,250vdc on the output terminals.
Q202 and Q201 are getting very hot, but nothing else is getting hot, neither test bad in circuit. They are PZTA56 and PZTA06.

So far I have not been able to locate a fault, any help would be appreciated.

I am wondering how best to design a speaker to have the tightest lobe, beam, or dispersion. Usually, we try to have dispersion be as wide as possible, so the speaker sweet spot is wide. Here let’s go in the opposite direction.

One application might be to make a speaker for Dolby Atmos in which you can bounce sound off a ceiling. I know that such reflections are not a good way to go for Atmos. But I can’t reach my ceiling easily and don’t want speakers up there. (15 feet high, vaulted). Mostly, though, this could be a fun design exercise and I’m looking for a next speaker project. As simple as it may seem, I have not been able to find enough information on this topic. So let’s see what would make for the best design.

What is out there already:
I’m probably missing a lot. But here is what I have found so far. Most Atmos speakers look like the following. Basically, an MT speaker angled up. Probably spraying sound all over the place. Not good. Let’s not do that.


There is an interesting thread here where horns and parabolic reflectors are used. But the conversation moves toward needing stadium level projection distances and the designs don’t seem suitable for, say, a house that you actually live in. 😀
https://www.diyaudio.com/community/threads/extremely-narrow-directivity-speaker-design.358588/


There are ultrasonic arrays, which give very narrow dispersion. My limited understanding is that they are not really good for music or movies.



Then there are speakers with 4 drivers arranged in a square. Here is where things start to get really interesting. At least to me. There is a commercial option from Triad. And one DIY option:
https://www.avsforum.com/threads/javs-diy-dolby-atmos-mkii-modules.2378314/



Four drivers in a square:
Let’s explore this idea some more. Will it work well? I don’t know. Any thoughts out there?

Look at the classic MTM speaker design. Note how the middle, dashed plot (2nd order Linkwitz-Riley, LR2) shows a nice, single lobe. Looks great so far. This image is for vertical directivity. If we also want narrow horizontal directivity, we would have a horizontal MTM. (Like some center channels.) Basically, we end up with the four drivers in a square plus a tweeter in the middle.


Crossover or no?
In the image above, notice how widely different the dispersion is depending on the crossover choice. An LR2 appears to be best for this current purpose. I do not know if that LR2 is electric, acoustic, or both. At any rate, I know that hitting LR2 is very challenging when designing a speakers. I have a couple of designs under my belt and was able to hammer things into shape and hit LR4. But LR2 is tough. And if we stray away from LR2, according to the image above, we may quickly lose the whole point of the exercise here.

So maybe it’s best to have no crossover at all? A full range speaker. With 4 drivers in a square. Like the Triad and DIY designs mentioned above?

Which drivers:
I guess the first question here is whether or not there will be a tweeter used. If there will be no tweeter, I guess just find the overall best performing full range driver. If we have a tweeter and a crossover, maybe try to find ones that are as flat as possible in the crossover region to have some hope of hitting an LR2.

Another option might be to have both a tweeter and woofers, but try to, effectively, have no crossover. Find a tweeter with relatively flat frequency response. And a woofer that is also flat. And for each, they have a natural tendency to drop off output around the same frequencies. So that they, effectively, sum up to be about flat without any crossover. I tried a project like this for an MT design once and it came out OK, not super. Add a resistor to drop the tweeter output down to the level of the woofers. Add a low pass cap to the tweeter to prevent it from getting fried from pops when you turn on the amp. Otherwise no real crossover to alter the directivity.

As frequencies go low, directivity also decreases. So there is probably not much need for the drivers to play below, say, 100 Hz. But we can always cut that off with the processor, anyways.

Ideas?
I am curious to see what thoughts everyone might have on this topic. Thanks!

Need a power transformer for a Heathkit W5m amp.

SOLD

A pair of Tamura TF-3 line output transformers. They have superficial scratches but are in proper working condition.

200USD ( shipping registered + tracking covered)

PayPal FF only please.

Anyone out there know of a decent lead free solder which flows as good as the tried and true 60/40 or 63/37 Kester stuff?

Its mostly for reflow work repairing old stuff, so it needs to wet and flow just as good without 900 degrees of heat. Most of the older audio stuff uses wave soldered and hand retouched PCBs. You want to keep the heat down to a minimum with those more fragile, older though hole components.

Hello all,

I'm after some ideas please. Some time ago I sold my last speaker setup - 2 x xls10s in sealed boxes and a pair of sealed mtm speakers. The mtm speakers were made with 8 inch midbasses and 1.25 inch SB Acoustics tweeters crossed over at 1kHz.

I would like to do things differently this time. Just not sure how...

The original system was fully active (3way) with a low cost DSP. Still got the DACs and DSP and homemade / designed 4 channel amp. Would like to re-use these.

Have 2 x Dayton Audio RSS390he drivers and a QSC RMX4050 amplifier towards the new system already.

Not really limited when it comes to cabinet size. The room is 21ft long. Would like to be able to listen to organ music properly so need decent low end. No aversion to professional drivers. Need to keep cost reasonable.

One limitation of the original system was the listening sweet spot. It was about the width of my head.

The new setup needs to be an all rounder.

Any thoughts would be very much appreciated.

Thanks,

Paul

I've searched the forum and gone back and forth with Wondom, even sending them videos and having them respond with instructions to do exactly what I showed them I did in the video. Apparently I am not the only one. Even when I have managed to get the pcui to recognize the jab2+(by not following the instructions btw) it will not save anything...even when I close the software the save doesn't work, have to hit 'do not save' to get it to close.

I've tried two boards and multiple computers with the same result. At this point I've tried every order of connection. Any tips, tricks, different software, etc. greatly appreciated I really need to wrap this project up.

Jason

I found this PS module at eBay. I am curious if anyone tried it.

https://www.ebay.ca/itm/36436657558...uid=uMxPcLkpRsm&widget_ver=artemis&media=COPY

I have had another terrible idea, and I'm looking for someone irresponsible enough to encourage me!

I want to build a center channel to go with my main speakers. My speaker design is a bit unconventional, so I'm looking for the same with the center channel: https://www.diyaudio.com/community/...on-of-integrating-multiple-subwoofers.401343/

My first idea was to use the same coaxial driver I have in my mains--12" B&C 12FHX76. But that would be a really tall center speaker! And I have found that while it plays down to 100hz reasonably well, the mids sound a lot better when I cross it higher.

So the next logical step is to do a MTM style center, but instead it is a WCW...woofer, coax, woofer. I'd use a 5" or 6" coaxial driver, probably B&C. And 2 woofers the same diameter as the coax.

Then I had the worst idea. Why not make a box like a line array boxes used in pro audio? It would be the MTM style, but the drivers are angled so they are closer together than a standard MTM design. I think this would help horizontal directivity? This one could be a 2 way or 3 way. The 3 way version would use a coaxial, and the 2 way would have a horn/ compression driver.

Right now I only need a center channel, but if it works out, I'd eventually build a few more for surrounds as well.

Requirements are frequency response from 100hz to 20k(-ish), 115dB (impulse, peak) across that range, and compact (i.e. thin) enough to work as a center channel. Drivers are 6" diameter or smaller, and use a compression driver/horn for high frequencies. I want the design to control horizontal directivity as much as possible.

This image is a good representation of the general concept. They are common in pro audio, but I've never seen a center channel made like this. It's probably a terrible idea?

After many years of designing and building solid state electronic circuits for amateur use, i have recently started to get interested in building speaker boxes. i have joined this website because i hope to find many interesting projects in this field.

I have for sale several empty PCB boards. Pictures are in attachment in the same order like below. Shipping worldwide.


1) USSA power amplifier boards (set of 2), price: SOLD

2) Hifi sonix Ripple eater power supply boards (set of 2), price: SOLD

3) Universal dual rectifier power supply boards (1 piece), price: 10 EUR (piece) + PP fee + shipping costs

4) Universal capacitor add on pcb board (1 piece), price: 5 EUR (piece) + PP fee + shipping costs

5) Koifarm (ex. diyaudio member) Purifi ET400/NCx500 passive input buffer (set of 2), price: 20 EUR (stereo set) + PP fee + shipping cost

6) Koifarm (ex. diyaudio member) Purifi ET400/NCx500 active input buffer (set of 2), price: 20 EUR (stereo set) + PP fee + shipping cost

7) FSSA power amplifier boards (set of 2), price: SOLD

I have a pair of Speakerlab S7 speakers that I bought as a kit in 1978, gave away in 2006, and have recently re-acquired. They have been abused (dropped) while not in my possession. When they were recently given back to me, one speaker was dropped hard enough to have the 12" woofer popped out of its RTV nest, and it appears the big mid-range resistor tore out the connection to the capacitor in that circuit during that event. I hooked up the one complete speaker that still seems intact and heard that wonderful sound that I loved so much years ago. I have decided to attempt repairs, as I would like to enjoy their sound for the time I have left, so am asking for any hints, tips, guidance in getting the heavily damaged speaker talking again.

It appears that one of the crossovers was damaged in that the lead from the 12uF 100V non-polar capacitor [Rubycon] (picture below) was torn out of the capacitor body. Paul Johnston from The Loudspeaker Store was kind enough to respond to my e-mail and get me started on the parts quest and not make the process complicated. My need is simple: I just want to get this damaged speaker working enough so it can work together with its aged (but apparently intact) partner for a little while. I would like to get close to the original specs in replacement before I seal up the cabinet with RTV. I don't have a "listening room" any more, but will simply stack the two and leave them wherever I can find room in my tiny office where I hide out. Won't be able to muscle these 95 pound beasts around much longer without help.

Getting the old RTV off of the woofer cabinet face is a challenge without tearing up the MDF mounting board - any hints other than being extra careful in peeling this nearly 50-year old stuff off without destroying the MDF?

I was planning on using RTV silicone to button things back up once it produced sound again - all the individual horns and woofers seem intact, and produce sound when tested. Hoping there is enough lip left on the MDF board for that woofer to hang on to. I will be heeding the advice of others here and refrain from hot melt glue. I am not in a good enough shape to install hardwood backer for T-screws. I suppose it's RTV and pray... any other thoughts appreciated.

---

RB in flyover country USA - Mountain time

Hi everyone,


I’m Diego, i'm new to the forum! I’m starting to get into repairing audio electronics and currently working on fixing my Washburn bass amplifier. I’m also interested in building DIY guitar effects.


Excited to learn and share with you all!

Hello everyone,
I’m a tinkerer in radio and audio electronics. Sometimes I do even excursions into digital electronics like Arduino. Hope for some exchange of knowledge if I get stuck somewhere in my projects.

Howdy all,
I joined because I am a dabbler (at best) and appreciate the circuit designs and PC boards offered by the more expert members here. After focusing more on family and children, I am approaching empty nest and restarting hobbies from my younger days.
I come this way because of my interest in synthesizers (and generally electronic music) as opposed to home audio. My last project before my break was a Paia Theremin. I am currently interested in working on an active LP filter with tube amp as an experiment in de-digitalizing my analog-modeling synthesizer.

G

I am modifying a speaker cabinet and need to have removable panels. The panels are Valchromat (a bit denser/stronger than MDF) and are 19mm or 12mm and some need to be screwed/bolted into from the side, therefore risking splitting.

For this reason I have planned to use threaded insert, e.g. m4 bolt into an 8mm (OD) threaded insert, 8mm insert goes into 12mm panel. Very tight if used on the side. And also may be a pain to align.

Is there any other way to do 'bolt-able' threads on MDF? Maybe some specific product that I can put inside a hole, then put a screw or a bolt in, let it dry and then screw out (i.e. it would not stick to steel), while still maintaining the reasonable integrity of the thread for infrequent re-use?

It is a vary nice sounding dac .
520$ shipped in the USA

After the power outage in North America a few years ago most utilities no longer run their generators on voltage control, they run on power factor control and one power plant controls the voltage. Why? If all the generators are set to voltage control and a plant goes down, the smaller plants try to maintain the line voltage which makes them over load and trip out. This is what caused the big outage here.

Now the line voltages vary a lot more than they used to. Add in solar and wind from the individual consumer putting power back on the grid and not all the these systems regulating well (think cheap gear) and the issue is compounded.

I like the resistor. Simple solution for a simple problem.
Mike

So I was doing some stability testing and found that even without pure capacitance on the output the positive side of the amp breaks out into oscillation. What was interesting was when I tacked on a 1uF cap on the output it appeared to start off as a ring then break out into oscillation (video attached). Meanwhile the negative side was perfect. The oscillation is not there when the fault relay is open. I can attach a schematic if needed.

Hey guys. Finally, I got around to assembling my own console. I already have ideas for channels and circuits for them, but the most important element is missing - the summing circuit. A mixer without a summing circuit cannot be a mixer. Yes, I certainly know many passive circuits of the simplest summing circuits based on potentiometers and 5 resistors. But this is not what I need. I wanna get vintage warm and flash sound and I am looking for active or passive summing circuits from SSL, API, Neve, Neumann, Studer. If you have such circuits or know where to find them - please tell me. Or can you tell me how the adder works, not necessarily the actual diagram, the main thing is to understand the essence and create something of your own based on it.
I've also heard about such a scheme:
Each channel has a neve 1272 or Neumann preamp at the input of the combiner, and then a fader and resistor based circuit that combines all channels into one signal. The idea as to me is not bad, but only for the section of groups, that is the sum of 4 groups in one channel or master channel, and then stereo isolation and output amplifier. But I need a summarizer for the channels as well. To be able to select the group to which the summarized signal will be sent. What can you say about it?

Hi

I posted below on the Martin Logan forum and was advised to try here. Essentially I have one panel not delivering high frequencies; it isn't the panel (they're quite new) and has been identified as the crossover/power supply. I have a techie who has done some diagnostic work and has asked some questions, below.

If you have any thoughts please chip in.

Techie questions:

1. The EHT seems to be working and measures 2200 volts which is the same as the working board
2. I have swapped over the 4 channel Op amp and that is working
3. I have tested the high value electrolytics C3, C8, C5, C6 they are all OK
4. I have replaced the triac - that is OK
5. I have tested the transistors Q2 and Q3 – they are OK
6. When powering up the LED lights OK but goes out after about 2 minutes

I would welcome some useful information such as:-

1. A detailed description of the operation of the circuitry
2. A test-point map with expected voltage readings
3. Suggested probable fault given the info 1 to 6 above

ML want £309 for a board which 'usually solves the problem'. Am I right in thinking as it's the power supply board only, I don't need two boards to match speaker outputs?

Thanks in advance for anything you can offer!

Mike

Looking at some of the small (3 inch or so) fullrange drivers and the better ones seem to have excellent frequency extension and off axis response along with the ability to cross much lower than domes and the like so the question…..seems like a great choice to mate with an 8-10” woofer for a 2 way.

Some interesting comments by bolserst about inverted electrostats (Final, Loewe) hidden in a now closed thread about BG Neo10 magnetostatics:

https://www.diyaudio.com/community/threads/bg-neo-10-and-neo-8.204465/page-10#post-3016843

https://www.diyaudio.com/community/threads/bg-neo-10-and-neo-8.204465/post-3017520

Quote:
Most ESLs charge the diaphragm with a high resistance coating and drive the stators with audio signal from a step-up transformer.
- Advantage is vanishingly low distortion if coating resistance is high enough to achieve constant charge operation

Inverting ESLs using a highly conductive diaphragm and drive it with audio signal from the step-up transformer.
The two stators are connected to equal but opposite polarity HV supplies.
-Claimed advantage is 6dB greater sensitivity which is possible, but seldom seen in practice due to other design practicalities.
Results of comparison test between the two drive methods posted here:
http://www.diyaudio.com/forums/planars-exotics/199943-measuring-sensitivity-esls.html#post2779302

-Obvious disadvantage is the inherent non-linear driving force with conductive diaphragm,
not to mention the reliability issues with the conductive coating.

and on the question of whether inverted had inherently higher harmonic distortion

Correct.
For conventional constant charge method, force on diaphragm is proportional to signal voltage and independent of position of diaphragm in the gap.

For inverting method, force on diaphragm is proportional to the square of the signal voltage and is also a function of the diaphragm's position in the gap.

Hi
I'm a Martin Logan SL3 owner and when they're running they're breathtaking, but sadly they're not at the moment!

I live in Scotland.

MIke

at least when it comes to home use this topic has certainly been discussed plenty all over the internet but i keep coming back to it because anytime i have to design a multi-way system there is always temptation to use something other than 80 hz to cross to the sub and i have to remind myself why it is 80 hz

and for me personally the reasons aren't what is being cited by others. for me it comes down to 2 factors:

1 - 80 hz is the highest frequency that is safely outside of the range of human voice

2 - 80 hz is the highest frequency where you can be certain any prosound subwoofer driver ( and by that i mean the big boys like the 21" Eminence ) can reach this frequency cleanly.

you can't really go higher than 80 hz for that reason even though LFE ( Low Frequency Effects ) channel goes to 120 hz but remember it is "LFE" channel it is not "sub" channel. your processor can send LFE to the mains on other hand they will never mix human voice into the LFE even if the male speaker's voice reaches well below 120 hz.

the purpose of LFE channel isn't to separate frequencies ( your system already has crossover for that ) but to separate content. voice goes into main channels. explosions go into LFE. this allows you to run the LFE channel hot ( which you're supposed to do ) and have properly loud explosions without muddying up speech.

a 80 hz crossover would allow you to do something like that as well but it has to be 80 hz and not 120 hz because it's just a frequency division network and not a guy in the studio that has more power over what goes into which channel. they can get away with 120 hz for LFE but we have to stick to 80 hz for XO at least as a general rule of thumb / best practices / starting point.

and as for why not go lower than 80 hz it's because you can't use main channels to control room standing wave modes. those begin from about 250 hz and down so ideally you would run distributed subs up to 250 hz to control the standing waves except you can't for reasons mentioned. rather you will need to use room treatments that are effective down to 80 hz ( which is a bit of a stretch but doable ) and distributed subs take care of the modes below that.

now for prosound you are facing different tradeoffs. and i know there are people here who know more than me about prosound so please correct me if i am wrong. but in prosound room standing waves are less of a concern and rather the issue is that speakers are usually flown over the crowd so you try to keep their weight down. on other hand subs can sometime be placed on the ground which allows the use of bigger, heavier subs and also gives you the 6db bass gain from the ground plane boundary versus a speaker suspended in free space up in the air.

but because you don't want to deafen the people who will be next to the ground sub stack you want to keep crossover frequency low because people can tolerate loud SPL better when frequencies are lower.

prosound arrays are usually made long to fit as many tweeters as possible because there is often not enough HF reaching the crowd for a number of reasons which means that there will be often a surplus of woofers and with the mutual coupling of the woofers at low frequencies even smaller ones like 10" will usually be able to reach 60 hz which then can be the crossover point to the ground stack subs.

again, i know it's not that simple and prosound guys should correct me on this.

but i think it is interesting just how bad prosound subwoofer drivers are above 80 hz considering their stellar efficiency. for example look at this distortion chart from the following link:

https://audioxpress.com/article/Test-Bench-Eighteen-Sound-18TLW3000-18-Dual-Voice-Coil-Woofer



distortion is lowest at around 60 hz, then doubles by 150 hz ... and this test is in FREE AIR which disadvantages lower frequencies

so this sub is perfectly optimized for its intended frequency range. the rise in distortion at lowest frequencies is unavoidable due to high excursions but the bump around 150-200 hz could have been designed out ... but there was no reason to as this driver will never see those frequencies.

for this particular driver the XO could be stretched to maybe 100 hz, and with some other drivers maybe to 120 hz but i still find it fascinating how true subwoofers like this exhibit this mess right above intended crossover frequency while woofers of similar size do not. to us lay men a paper cone is a paper cone but clearly there is more to it than that. subwoofer, woofer, midrange and full range cones appear to behave differently and it's not about the diameter of the cone. or it may be down to suspension or something else, but the effect is clearly seen in basically all subwoofers Vance Dickason has tested even though he doesn't talk about this.

on a side note this is also why i believe in multi-way designs. drivers can be better optimized for a target frequency range. even though you can certainly build a full-range 2-way i like to keep subwoofer, woofer and midrange separate for this reason.

Good day friends!

-----------------------------------------
UPDATE 2021-09-09

Version 0.6

Hey! If you are here just looking for the most recent version's:
- Schematic
- BOM
- Gerber files

please head on to Posts:
- #105 : Schematic and BOM
- #108 : Gerber files

If you are interested in the rich discussion prior to those results, keep on reading! 😱
-----------------------------------------

I recently bought the wrong switch! 🙂 A momentary switch instead of a locking one. That triggered an entire process which ended up with the PCB layout I offer here, initially for review / critique from the community, as this is my first PCB design, ever.

So, before getting into details, I would kindly ask that you share any and all comments you can give: ideas, concerns, pointers as to where to research further, anything you consider would be useful. This is not a finished product. Please, do not reproduce (yet!). Eventually, these will be made into publicly available Gerbers.

With that out of the way, here's the On/Off switch PCB literature and motivation, schematics, PCBs and hopefully a lively discussion before this becomes a finished product:


Background

I require a mains switch that works with momentary switches (much more handily available) and that does not see mains current. There is such a project here on this forum, it is Mark Johnson's H9KPXG (PCB: low voltage On-Off switch drives AC mains relay \ includes soft start .. H9KPXG).

Mark's solution has also a soft start, which I don't necessarily need. Also, Mark's solution has an already designed PCB, this project seemed simple enough as for me to give it a shot in designing a PCB with a more or less simple circuit.

Which circuit? Not mine, no... I know nearly nothing about design. Mark kindly pointed me to Rod Elliott's Project 166 (Project 166).

After getting permission from both R. Elliott and M. Johnson to design PCBs based on their solutions, here's what I have come up with:

• A dual board PCB configuration
• One board handles the mains, the relay switch, and a 12v PSU for general use in your system (more on this later!)
• The other boards holds the logic to drive the relay. The idea is that, if anyone favor's something different to the 555 chip, you can simply implement that... hopefully.
• In theory, both boards are stackable as to use less footprint
• Boards adhere to the 10mm mounting hole system widely used in the store, but NOT to the heatsink mounting system. They could be adapted if someone thinks they are useful mounted in the heatsinks, but not likely

Those are the basic "highlights" of the design.

Getting into more specifics, here are the schematics and PCBs:

Mains Board + PSU





The mains board is a merging of Project 166's Figure 3 (Typical Mains Switching Circuit) with M. Johnson's implementation of the small brick-type PCB PSUs that I think could be much simpler than using a dedicated transformer and PSU just to drive the relay.

• First and foremost, credits and attributions: the circuit designer is Rod Elliot, the PSU filtering system is designed by M Johnson. I have included both names on the PCB out of respect, but it is not their "exact" design, so this also may attach their names to something they don't want to. What is the usual practice here? Leave out anything and credit them here? Put something like: "based on", even if its 99% theirs? Please advice as to how is this usually carried out. Thanks!
• It's a dual-layer PCB, but bottom layer only has Ground. Should I just remove the bottom layer, or keep the ground (which mirrors the top layer ground exactly)?
• Instead of laying out 110V or 240V specific layouts, I provided two L+ connectors and two N connectors so that you can pair your transformer secondaries on individual block connectors.

Regarding changes made to P166 design, I have "stolen" (with Mark's permission) his PSU implementation. The biggest highlights are:

• Mark is using a 5V PSU, mine is 12V, so the values of the resistors, capacitors and inductors may not be ideal for this design, I'd appreciate input on this
• I am looking at RTD14012F for the Relay. Maybe 16A is overkill for PREs and other low current uses, and if you want 16A, you probably want Mark's soft start, so maybe a different Relay?
• I talked a bit to an engineer and he believes that C10, C11 and C12 may be 3 different caps to prevent oscillations in three different places of the PCB, and that they may not all be needed. So I kept just one (C3) on the PCB. I'd like also feedback on this, my research may be wrong here and I really need the three caps to filter out the specified frequencies.
• I have left a provision for R3 + C4 to control the current into the coil, but the PCB is laid out in such a way that a single jumper over R3 will remove the entire block if you want to keep the original P166 design without any changes
• I have left a provision for Mark's filtering of the PSU, but if you jumper L1 and don't install C1, C2, C3 you get the unfiltered PSU +12V with a single jumper.
• You could avoid the entire earth/chassis protection by not installing R2 and B1 (obviously, then the chassis connector on the euroblock is useless)

What do you guys think? Does it work?

Logic Board







The logic board is a direct implementation of P166 Figure 1 (Push-on, Push-off Switching Circuit).

• It's a dual-layer PCB, with the bottom layer used only for the +12V rail.
• It stacks on top of the other PCB, blocking out the top screws of the bottom euroblock, so that may need some rethinking. At the very least, you want to screw the bottom cables before stacking them. Yes, maybe this is not the best design.

That's about it. I am unsure about the trace sizes that are recommended for different applications. I have tried to keep:

• +12V rails traces have 0.8mm
• Mains traces (110V, N and Chassis) traces have 3mm (and no ground plane near them
• All other traces have 0.4mm

Again, any feedback of placement, trace size or distribution, building considerations, etc. is very welcome.

Thanks for having a look, best regards,
Rafa.

Hi

I got an original Electrocompaniet 25 watt 'The two channel audio amplifier' This model was made by Norse Ecosse Electronics. This amplifier was badly tweaked. The job was really butchered. I want to restore it in it's original condition. I need the power supply and protection circuit schematic with the parts list for the Norse Ecosse Electronic model.


Thanks a lot

Marc Legare

I have a preamp with a Rf remote control.
It's a alps rk27 style 50kax2 motorised volume control.
The receiver is a RF model but the remote control is missing and not available.

I search a RF (not IR) transmitter emitter which fit.
Or the way to tweak something

All the best

Hi !

I'm a last year french student who's doing an assignment in order to graduate. I need some PA System techs to answer some questions in order for me to answer the question : What are the differences and the common points between tuning a PA System when it's indoor or when it's outdoor ?
If some of you could help me, I would like it a lot ! I link the forms I made with all the questions : https://docs.google.com/forms/d/e/1...Wxc886X6U0iCk8yZyNIKxEEQ/viewform?usp=sharing

If this doesn't belong here, I'm sorry and don't hesitate to tell me 🙂
Thanks a lot for your time !

Hifidiy CD transport Chassis for the Philips CDpro2 series of drives. comes with remote control. has a nice Digital output section. Was going to use this for a project but have since gone another way. heavy duty chassis. very nice metal work. has been tested and it works great. Does NOT come with a CDpro2 drive. you will have to supply your own. Has some scratches and marks.

$100

Looking to buy a pair of the Siemens d3a tubes. Anybody have some for sale? Thanks!

I'm interested in purchasing the complete set (or large chunk) of Linear Audio volumes in hardcopy. Shipping to Pittsburgh, PA.

As of now I have volumes:
None 😿

Thanks!

--Jonathan

Just thought I’d share a photo of a faceplate I made to give the WiiM Ultra a ‘70’s Retro look. It’s really just a shelf that the WiiM slides onto. The faceplate is put together from 4 pieces of aluminum using JB Weld (metallized epoxy). Marantz faceplate bolt tip.

Hi,

Just got a Mooer Little monster AC, 5W single ended EL84 guitar amp.
I've tried to trace the PCB and draw the schematics, it's incomplete, maybe some mistakes here and there, but since I didn't found anything about it's better than nothing
I've made some measures on resistive load, it's almost linear from 200Hz to 8k, output transformer looks like a good one. Clipping begins at 7V - 8 ohms (3W)

EDIT : added inside pics. Yellow caps from the first pic added by myself for testing purpose. First mod done by increasing "mellow" cap to 47n for more bass. Amp provides almost a flat response starting from 150Hz instead of the default 300Hz.

Hello! Anyone that can help me figure out a replacment choke for a line filter in a amplifier? The part says MLF 16-004. T21 in service manual but nothing else. What could it be?

Hello,

My latest creation.

LVPS DC-AC Regulated Inverter EGS

This DC-AC regulated power supply board is used to power the audio tube heater with AC voltage. The voltage is adjustable from 4V to 8V via a potentiometer on the PCB.

The LVPS DC-AC Regulated Inverter EGS board is based on the use of the EGS002 module. It is a control board for pure sine wave inverters, primarily used in DC-AC power conversion systems.

It integrates the EG8010 chipset for generating pure sine waves with digital control and dead-time management. The module supports fixed frequencies of 50Hz and 60Hz, as well as adjustable frequencies ranging from 0 to 400Hz (need mods on the EGS002 module).

It offers protections against overvoltage, undervoltage, overcurrent, and overheating. The board is also equipped with an independent fuse to protect the EGS002 module (5V and 12V). To avoid damaging the tubes, there is a 3 second soft start mode by default.

The LVPS DC-AC Regulated Inverter EGS board operates up to about 4A with an input voltage of 15Vdc or 24Vdc. It can be configured with different inductors in the output filter depending on the types of audio tubes to be heated and the needed power.

The board has an output on 3 pins with an optional middle point (2 resistors to be soldered under the PCB). This avoids soldering the cathode resistors onto the tube socket.

Gerber and documentation files are available on my GitHub repository.

This power supply has not yet been tested in real time on a tube amp. This will be the next step as soon as I have completed another related project.

Enjoy !

Stef.

Hello everyone,

I am looking for a schematic and advice to design the complet system below. Thank you for your help.

Hi.

I have a bit of older MF gear, and I've been looking for some extra power amps to complete the HT setup.

I picked up a P170 the other day, it must be '80's gear, but I can't find a production date on it, so I'm guessing. Anyway, I'm going to replace all the Electrolytic caps in it, and then see how it compares to my other P150 and decide if it will be front or rear...

There is some evidence of previous repair inside, It looks like one of the caps has let go at some time in the past - there's a burn on the circuitboard near one of the transistors, and one of the 100uf/63v caps doesn't match it's other brothers - it's a 100v job, and a different brand - photo attached.

Apart from the cap replacement, is there anything else I should be looking at? The amp runs ok, and sounds good on my test setup of old bits 'n pieces.

Should I be looking to up the spec to 105 degree caps? They're 85 degree in there at the moment.

Any history on the P170? Unlike my other P150, this has a rear heatsink, and it weighs a lot!

Thanks,

Michael

Hi,

I am looking for 8-10 pcs. NOS.

Its been a while since I have contributed to this forum so thought it could be useful and informative for others to post details about my recent Musical Fidelity A1 re-build. The re-built amp sounds pretty amazing and well worth the many hours of effort slaving over a hot soldering iron and emptying my pockets to buy replacement components😀

To summarise the re-build:

1) Replaced direct wire 2-core mains lead with proper 3-core mains cable attached to an in-line 3-pin IEC plug, PE connected to chassis. The steel case on this amplifier is really hard to cut so this mod gives a mains IEC connection with very little effort.

2) Fitted a decent Ground Loop Breaker (Rod Elliot ESP) to replace the original 3R3/100nF parallel circuit attached to the chassis green 4mm banana post.

3) Upgraded the original 06A10 6A rectifier diodes with 10A10 10A and fitted 47nF 250V capacitor filter across the AC on the board. Possibly, a high current bridge rectifier may have been even better.

4) Re-capped the PSU capacitors, with as much as I could squeeze in to try compensate for the rather puny mains transformer. This involved using my Dremel to drill new capacitor mounting holes - 12000u + 2200u + 2200u followed by 12000u + 2200u, the original 0.47R 3W dropper resistor was replaced by 0.56R 5W which I had available. The 2200u were low ESR, 105C rated however the main Nichicon capacitors were standard 85C (I know, I know!).

5) Replaced the signal input 1u electrolytics (C6 & C7) with 1uF MKT and other electrolytics with same or better value/rating 105C replacements.

6) Removed the quad TL084 op-amps and re-fitted in DIL sockets, just for fun.

7) Isolated the existing pre-amp output using a 2-pin shunt jumper (open) and fitted direct input phono sockets to the power amp section, connected across resistor R3, 100K. I fitted a 2K/1K resistor divider onto the phono sockets to match the signal levels from my source. NOTE: This must be connected to a pre-amp or an audio source with volume control/adjustment.

8) Replaced the original MJ2955/2N3055 with MJ15023/MJ15024 transistors and fitted new silica washers with heat-sink paste instead of the dry thermal Silicone pads. Its important to do this because the pads may have deteriorated due to the repeated hot-cold thermal cycling and will have loosened off the mounting screws anyway. I fitted a heavy-gauge silicon wire collector connection to the board.

9) Replaced the board to output speaker connector cables with similar heavy gauge silicon wire.

10) Resprayed the top heatsink cover with 2 - 3 coats of matt black high temperature "stove" paint, good for up to 600 deg so should be ok with the A1 toaster.

Probably the most important improvement was to by-pass the existing pre-amp circuit, which is well-documented to be a poor design and bad implementation. Secondly, the seriously beefed-up PSU supply does wonders for the low end bass performance and general mid-range dynamics. Its warm, lush sound may not suit everyone's musical taste but its getting plenty of playing time with my music collection, its a definite keeper. I am a Musical Fidelity convert and have just bought an el cheapo B200 and am in the process of yet another re-build 🙂

Matched 2sk170gr/2sj74gr quad
24usd

2sk170gr matched quad
18usd

shipping 10usd +PayPal fee or friends family option
Tracking+5usd

0.05ma matching
There are more to measure
Shipping with tracking number (Japan post)

Matching from 40 pairs.

yesterday I asked Grok:

DIY 50W guitar tube amp?

A 50W tube amp is a solid step up—great for gigging or just cranking it at home! Building one is more involved than a little solid-state amp, but totally doable with some planning. I’ll outline a classic single-ended or push-pull design (push-pull is more common for 50W). Think along the lines of a Fender Bassman or Marshall Plexi vibe, but simplified for DIY.
Parts You’ll Need:
Tubes:

• Power tubes: 2x EL34, 6L6, or KT66 (push-pull pair for ~50W). EL34s are punchy and Marshall-esque; 6L6s are cleaner and Fender-y.
• Preamp tubes: 2-3x 12AX7 (ECC83) for gain stages and tone shaping.
• Rectifier tube (optional): 5U4 or GZ34 for tube rectification, or use solid-state diodes for simplicity.

Core Components:

• Output Transformer (OT): Critical for 50W. Match it to your tubes and speaker impedance (e.g., 3.5k-4kΩ primary for EL34s, 8Ω secondary). Hammond 1750 series or similar works.
• Power Transformer (PT): Needs to supply ~300-400V at 150-200mA for the plates, plus 6.3V for heaters. Look for something rated around 200VA.
• Chassis: Steel or aluminum box to mount everything. Punch holes for tubes and controls.
• Speaker: 8Ω or 4Ω, 50W+ rating (12” Celestion or Jensen are popular).
• Capacitors:
  • 22µF-47µF @ 450V electrolytics for power supply filtering.
  • 0.022µF-0.1µF @ 600V for coupling.
• Resistors: Various (1W-2W rated) for bias, cathode, and grid circuits (e.g., 1kΩ, 470Ω, 100kΩ).
• Potentiometers: 1MΩ for volume, 250kΩ for tone (bass, mid, treble).
• Input jack: 1/4" mono.
• Switches and fuses: Power switch, standby switch, 1-2A fuse.

Tools:

• Soldering iron, multimeter, drill (for chassis), and wire (18-22 AWG).

Basic Steps:

1. Design the Circuit:
   • For push-pull: Two power tubes (e.g., EL34s) driven by a phase inverter (one 12AX7 triode splits the signal). Two gain stages (another 12AX7) and a tone stack (Bassman-style is straightforward).
   • Check schematics online—Fender 5F6-A or Marshall 1959 circuits are good 50W starting points. Simplify as needed.
2. Power Supply:
   • Wire the PT secondary to the rectifier (tube or diodes) to get ~350-400V DC after filtering with caps.
   • Add a choke (5-10H) or resistor (100Ω) between filter stages for cleaner B+ voltage.
   • Ground everything properly—star grounding avoids hum.
3. Preamp Stage:
   • First 12AX7 stage: 1.5kΩ cathode resistor, 100kΩ plate resistor, 0.022µF coupling cap to the next stage.
   • Second stage: Similar, feeding into the tone stack (search “Fender tone stack calculator” for values).
4. Phase Inverter:
   • Use a long-tailed pair (common in 50W amps). One 12AX7 triode, 10kΩ tail resistor, drives the power tubes.
5. Power Stage:
   • Bias the EL34s (fixed bias with a negative voltage supply, ~ -35V, or cathode bias with a shared 250Ω resistor).
   • Connect grids to the phase inverter, plates to the OT primary, and OT secondary to the speaker.
6. Assembly:
   • Mount tubes, transformers, and controls in the chassis.
   • Solder point-to-point or use turret board (safer and cleaner).
   • Double-check wiring—high voltage means mistakes can fry parts (or you).
7. Test Safely:
   • Use a variac or light bulb limiter to power up slowly. Check voltages: ~350V on plates, ~250V on screens, heaters at 6.3V.
   • Plug in a guitar, start quiet, and listen for hum or distortion. Adjust bias if needed.

Notes:

• Safety: You’re dealing with 400V+. Discharge caps before touching anything—use a resistor or screwdriver with a clip lead to ground.
• Cost: Expect $200-$400 for parts, depending on quality (transformers are the big expense).
• Sound: EL34s give a mid-heavy crunch; 6L6s are smoother. Tweak the tone stack for your style.

I'm looking for another port configuration for my tall 4 way cabinets w/ integrated subwoofers. I'm interested in making 2 ports that run vertically in a tall speaker cabinet, and exit out the sides of the cabinet with a flare somewhat resembling a NACA duct.

For reference, the speaker cabinet is 16"x 16"x 52". The subwoofer cavity is an "L" shape, allowing for a long and straight port. If I can figure out how to design it!

I already did a prototype with dual vertical ports positioned on either side of the sub driver. They exited out a notch in the bottom back corner of the cabinet. It worked well enough. But there is some audible distortion/ noise from the enclosed port exit.

I would like to improve on the same concept, with the ports running vertically in the tall cabinet section, but then venting them out to either side. (I have also thought about a vertical slot port against the back panel, that would exit right above the rear facing woofer...)

I haven't actually made these designs yet because I'm unsure about how to find the effective length and the end correction factor.

Photo of the concept:



I'm curious if anyone has tried something like this? I'm looking for a theory to calculate the "effective" length of such a port. Of course I will have to do some prototyping, but it would be good to start with an educated guess?

The drawing below is the speaker as designed with a 10" subwoofer driver. I built this one and used a curved port that fit neatly around the 10" driver. But it will be difficult to re-use the same curved port with the 12" subwoofer. Before I build molds to make a new curved port, I'd like to investigate the possibility of a simpler straight port...with a complicated port exit/ flare!

Hi

Is this circuit worth cloning ?
- or is it waste of time and money...

Comments please

cheers
JB

Hi, I'm happy to be here. I hope I'll find a lot of useful information here.

Hello,

I have a Mark Levinson 336 with all three surge resistors that are defective.

Which one can I use as a replacement?

I've already found several solutions here, but I'm still unsure.

I can't find the SP1976 with 10R at any retailer.

Best regards

Mario

I have taken several plots of my Purifi /Satori beryllium speakers, detailed in the thread 'Possible MTM Fun Project'.
I used an Omnicron USB mic and REW on a laptop. These have been useful in voicing the speakers, but I might like some advice as I'm not familiar with interpreting the plots or using REW in other ways.

First, here is a plot where it is now. Here are details of the crossover.
Bass: 2nd order 0.8mH, 50uF, very small notch at 3.5kHz; the 0.8 set by trial and error to give a reasonable bass level.
Treble: 3rd order 12uF, 0.28mH, 12uf; dropper 2 ohm/12ohm, with added 6ohm between crossover and speaker.
Note that the green line is the current state with 0.28mH; red is with 0.23mH.



I am not sure how good this FR is. Divisions are 1dB so it is fairly flat, but I don't know if this is 'acceptable'.
So I compared with other speakers, below.
Monitor Audio (old), stand mount bass reflex. I don't know the model number.



My SEAS ER18/27TDFC MTM:


The Monitor Audio sounds reasonable, the SEAS MTM sounds very good even though its FR does not look so good.

To me, the new Purifi/Be MTM plot looks the best, as with 1dB per division the variation is not that much. Am I kidding myself????

There is an issue, which Mark (who made a good TM with these drivers) points out; there is a dip at 1800Hz (xover frequency) and a peak just below.
I don't think I hear a problem, but then I don't know what to listen for.
I improved the dip somewhat by increasing the tweeter inductor from .23 to.28mH, but it also raised the peak somewhat.
So I am wondering if I should continue to try to improve the dip, or whether such a dip is minor, of a value to be expected and nothing to worry about.
If it is a case of accepting the dip (the sound is good), I will revisit the 0.23mH, as the peak below 1800Hz looks to be less.

Any advice welcomed.

When repairing som PCB's at work I came across the MC14541B timer IC for the first time. It's fitted on a board from early 2000's, I guess.

From what I can see from the data sheet it's pretty much identical to the well know CD4145 IC. Pin campatible, both CMOS and about the same supply. I can't see the difference. Ironically, 4541 backwards is 1454.

Does anyone know something about these? Think I'll use CD4541 in repairs, since they still available, though they are listed as obsolete, at least the DIP version.

low frequencies = cones. not too controversial. yes there are belt driven subwoofers, modulated fan subwoofers, there is Powersoft M-Morce moving magnet subwoofer etc. but for our purposes here we're just going to cover everything below 1 khz using good old dynamic paper cone drivers and we won't discuss them because they're boring.

but mid to high frequencies there are options, for example:

cones
domes
compression drivers
planar
AMT
true ribbon
electrostatic

probably forgetting some like Plasma tweeters ...

the question is what would be the perfect compliment of technologies to cover the range above 1 khz ?

my thinking on this question has evolved over time but as of two days ago it is as follows:

1 - 3 khz = BMS 4596ND ( annular diaphragm compression driver )

https://www.bmsspeakers.com/index.php-71.html?id=4596nd

3 - 9 khz = Beyma TPL200 ( pleated diaphragm air motion transformer )

https://audioxpress.com/article/tes...a-tpl200-h-pro-sound-air-velocity-transformer

9+ khz = Aurum Cantus G3 ( pure aluminum true ribbon )

https://www.parts-express.com/Aurum...6kDwku8s0r1xlyZU5_2n0FYdFRLdz9xUaAmGJEALw_wcB

those technologies are the most efficient, flattest measuring, highest output and lowest distortion in their respective frequency ranges.

for example the BMS midrange begins to fall apart above 3 khz due to "mass break point" ( apparently function of horn geometry ) and flex of the relatively soft polyester diaphragm ...

the TPL begins to fall apart above 9 khz due to the depth of the pleat putting an upper limit on HF response much like in a compression dome the spacing between phase plug slots puts a limit on HF response

while the True Ribbon can go well past 20 khz but is limited on the low end by the fact that it doesn't seal the air chamber ...

as well the TPL can't go very low either because the forces are side to side - no force front to back which means air pressure at low frequencies can push the entire diaphragm in or out which means that the air chamber is only FLEXIBLY sealed and it can only go marginally lower than true ribbon - nowhere near as low as compression driver

a planar can go as low as a compression driver because motor force is front to back and the chamber is sealed. the problem is that at frequencies below those which AMT can comfortably handle the planar is soundly beaten by the compression driver, by about 10 decibels of efficiency, while also having the benefit of user replaceable diaphragms. i think one reason you don't see many planars in prosound is you can't replace a blown diaphragm in a planar like you can in a compression driver.

you CAN replace a diaphragm in the Beyma TPL as well you can replace a ribbon in most good True Ribbon tweeters like Aurum Cantus, which offers both replacement ribbons and replacement instructions. RAAL also sells replacement ribbons for most of their drivers. With some ribbon tweeters you can roll your own ribbons as well.

and at frequencies above mass break point of compression driver the planars exhibit rather erratic behavior that isn't close to flat. in fact the planars aren't flat anywhere in the frequency range. combine that with planars having the lowest efficiency ( between CDs, AMTs and True Ribbons ) and being the only one of these four technologies with non-replaceable diaphragms and you can see why i have eliminated them from the "optimum" setup.

and thus the winning trinity ( as mentioned above ) is Compression, AMT and True Ribbon with 1 khz, 3 khz and 9 khz crossover points where the compression is a dedicated midrange from BMS ( or if you prefer B&C, but i think BMS is better ) and the AMT is Beyma TPL200 ( which i think makes a better dedicated upper midrange, while the TPL150 tries and fails to cover a wider frequency range ).

sadly there is no True Ribbon on same level of engineering as BMS and Beyma because major prosound companies like that do not make True Ribbons and instead for TR you have to rely on less sophisticated operations, most of them from Asia ( except RAAL ) and there doesn't seem to be one real winner between the Ribbons.

RAAL seems to be the highest regarded and does seem to have the best ribbon element but i don't like how they put the transformer inside the acoustical chamber. it strikes me as a cost cutting measure so they don't have to build a housing for the transformer like every other ribbon maker does and the downside is the chamber now can't be fully acoustically optimized. it is now both too large ( for a supertweeter ) and asymmetrical.

I got a Philips cd 303 with noisy outputs, so I replaced all the caps on the power supply and laser board, repaired broken soldier joints... And it worked fine.
Then I decided to change dac power supply caps, but when I was connecting dac board I misplaced two 3 cable connectors, the data and power supply I think.
Now only drawer works and mab8410p chip is getting really hot. I tried putting a chip from a cd 304, which is a little different, and with it it spins the disc but won't read, display doesn't work... but the chip is staying cool.
So, did I fry the mab8410p? Are there any replacements avalible?
Any help would be greatly appeciated.

I didn’t see this information anywhere else so thought I’d pass it along.
My Marantz 140 amplifier has four Aluminum bolts, one in each corner.
They are metric M5x0.8 and are 8mm long.

This site has some reproduction bolts for sale. They offer a set of four for the same price that I’m seeing on eBay for one.

VINTAGE HIFI AUDIO

I’ve been struggling with this for a while.

Had to replace a couple of resistors on the boards, so figured since I was going to tear the amp down, I should try another grounding protocol to see if I could solve what’s been an ongoing issue.

As the amp sits on its own, with no source, it is dead quiet. After readjusting the voltages on the boards, I am getting 1mV of AC on the output. Very happy about that 🙂

However, as soon as I hook up a preamp, I get a buzzing sound.

The photo attached showed how it currently is wired up.

Made use of a star ground. The secondary centres are connected to the star. The star is connected to one end of each of the power supply boards. The ground terminals on the amp boards are also connected to the star. The earth ground is connected to the star, and the chassis. I just tried connecting the RCA ground to the star also. Both the grounds of the RCA terminals are connected together and a single wire connects them to the star

What on earth (pun intended) am I not getting here?

Thank you for your thoughts.

P

Asembled and ready to use with all original parts that come with glassware kit.
Good up to 400V of DC out voltage.The heater are now for 6,3V output voltage but you can change that to what voltage you want.The both heater regs can be made also als symetrical supply if you need this.The board comes with original manual.Price 100 euro plus shipping.This board works perfectly!!

Thanks much to those of you who have answered some very basic questions I have so far. I have settled on a design for my particular driver and desired usage, and would like some feeback.

The principle driver in question is a Zenith 49CZ817.

I went down two separate trains of thought here, and ended up not going open baffle...mainly because I didn't want to have the speaker that far from the wall. And, I liked the thought of not needing a dedicated amplifier/dsp system.

I spent some time trying to copy and tweak the decca corner horn to match the size and t/s parameters of my driver, and it didn't really seem to work well. Backloaded horns tended to get too large (and definitely outside my skill set), so I compared MLTLs to the simple bass reflex. Back and forth, may times. And somehow I ended up staring lovingly at the onken style.

Well... that is not what I ended up with, since I really liked the concept of backward reflecting, along with a nice plant stand. But I definitely stole something from the onken and something from the decca...and probably a lot of other places too. I still have a few questions, before I fine tune and get all the numbers matching.

Attached is the design of the speaker, along with the T/S of the driver and a hornresp file which is close (not accurate to model), but shows the modeling strategy. A big box, with a big downfiring port...Not quite Onken big, based off what I read.

1). The ports fire down, and I can adjust height from the floor...but am unclear as to how to model this in hornresp. Is there a rule of thumb minimum here?

2). The angle of the speaker is 60 from horinzontal. It will be firing upward and backward into a corner that is 8.5' in height, and slopes up to about 17'. 60 degrees was pulled for aesthetic and math purposes. Is there a better angle to consider?

3). bracing. I have not yet added the bracing to the model, and know there will very likely need to be some. I have seen a lot of braces with the circular cutout approach. Is there some minimum hole size relative to being able to ignore, or else how do I model it. Or, do I do minimal bracing and accept that the Ql will be quite high? Looking at the rough modeling, this seems to be pretty insensitive to Ql. Though i have no idea what a Ql of 50 looks like.

4). Design - Am I missing something critical in a "never do that" sense?

5). Tweeter. As of now, I know I need something to get above 6-8K, and I have a kilpsch K-89-KV, which was ripped from a center speaker. I was going to throw that in the same baffle, and figure out the crossover once in. I know nothing about this, other than I have one. Any thought on how to present tis tweeter in its best light?

The back and forth between sketchup and hornresp is fairly intensive for me, so before going further down this hole....

Thanks for thoughts and opinions.

-jeff

Hi. Bought an audio note quest 300b that’s wired in series for 240v. How do I wire it for 120v. Pic attached and if u need the underside as well I can open and take pics. Thanks.

I have this equipment in need of repair. The frequency output is working fine except for its voltage level. For example when I set a voltage AC level of 1V, I only got 0.981 Vac, no matter which potentiometers I suspect is relevant.
Of course its difficult to find schematics and manuals for this OEM even from the WEB.
Any advise from members out there will be much appreciated. Thanks much.

I'm searching for anyone who may be able to steer me in the direction of finding someone to install an analog DJ mixer modification for licensing. Can anyone help?

The Marantz 2230 became a victim of my careless shorting of the output resistor to ground while checking BIAS. Several attempts were made to repair this channel, but they were in vain. The only way to recover use of this 2230 was with a Wondom amplifier implant served by the Marantz dedicated single rail power of 66 VDC (You might have seem my other thread rescuing a Mitsubishi DA-R35 with a similar Wondom PCB amp, actually have done two of those). This unit has three secondaries, one to run dial lights, one for pre and line stages and the radio, and a dedicated high amperage for the driver/power amp individual channel units.

I was able to use this single 66 VDC with the Wondom AA-AB32516 amplifier module that could receive up to 72 volts and output 500 watts at 4 ohms--even at lower 60 VDC voltage. I removed both original amp assemblies and their heat sinks, along with the main power cap and two channel output caps. I installed a small black walnut board to hold the Wondom as you see and removed all excess wiring. I was able to use only existing Marantz wiring to power the Wondom and the only wires added, unrelated, were to provide a dimming switch for the dial lighting. Hopefully, someone will be able to make sense of this and the photos below in case another 2230 finds itself in the same predicament. May I add that the sound is fantastic and modern. Some may find the cooling fan noise a bit annoying since it cycles on/off, but eventually you forget about it.

A bit of the fat magic of the Marantz sound is gone, but not all. Treble is way improved and so is focus of sound, probably due to improved speed of class D. I will eventually add a wiring diagram. Some pictures for now.

BTW, after several days, no pops or smoke, and another 2230 saved from a dusty shelf.

Hi Folks,

here is the start of my idea for a modular preamp.
The pic shows the control (without audio) schematic for a modular preamp with 10 slots for different in/out modules.

happy to answer your questions to this and open for additional ideas.

regards

HP

I'm doing some work on a 30+ year old Parasound HCA-1200 amplifier. I bought this in the USA, but now live in Germany, and decided to get rid of the bulky/ugly external step-down transformer and convert the amplifier for a 230VAC mains. Fortunately this is easy since the power transformer has two parallel primary windings, which can be put into series for a 230V input. See annotated schematic below (bottom left corner is the relevant bit).

Anyway, I have a question regarding the correct bias current for the output transistors. I found a table online listing the correct bias current settings for all Parasound amps apart from the HCA-1200. Does anyone know the correct value? In other words, what's the correct DC voltage across the 0.33 ohm emitter resistors on the output stage?

I wrote to Parasound to ask this, and got a quick reply saying "we don't know". I then asked if John Curl could be reached to find out, and they replied that he had lost the information in a fire. Perhaps someone here knows the answer...

Cheers,
Bruce

Hi, i just rebuilt a pair of JBL j900mv tower speakers on a budget and i want to set up a better crossover design than they came with.
The towers are built as follows:
8” chinese silver flute woofer
6.5” dayton audio fiberglass cone midrange speaker
~1.5” titanium tweeter that came with it
I was thinking of using the Dayton Audio XO3W-375/3K 3-Way Speaker Crossover 375/3,000 Hz as a prebuilt board which is way better than the 3.5khz crossover already installed from the factory. The speakers are also being paired with a polk PSW10 so the deep bass is already taken care of.
As a separate thought, i was thinking of using an inline high pass such as the Parts Express 100 Hz High Pass 8 Ohm Crossover
• this whole setup means the sub would play from 0-100hz, the 8” 100-375, the 6.5” 375-3,000, and the tweeter 3,000-20,000

OK i know Beyma TPL is not supposed to need a supertweeter ( although Joseph Crowe measured 15 decibel drop by 20 khz on TPL 150 )

and in fact some here believe Radian LM8K doesn't need a supertweeter even though on Radian's own measurements it drops like a cliff above about 15 khz

and i agree for prosound use they can just be used full range and i probably wouldn't even hear the difference but it would not be a true audiophile system IMO

reality is that some young women can hear past 20 khz ... in fact i used to know one who would put her ear against the magnesium alloy tweeter on my studio monitors and just listen to the tweeter because she was fascinated by the sound of it ... as much as i tried to stop her ( explaining it was very bad for her hearing ) she refused to stop ...

back then i myself could hear to almost 20 khz and i'm sure it's a lot less now ( haven't tested it in recent years ) but even if i personally wouldn't hear the roll off in the Beyma TPL i would like to have a speaker where NOBODY can hear the roll off.

most true ribbons will easily hit 20 khz and go well past it ... but would they be able to keep up with an array of Beyma TPLs ?

i know what you're thinking - isophasic you can't afford an array of Beyma TPLs ! and that is true - i can't ! not a floor to ceiling array anyway. but i was thinking what if i do like a partial array that is only about 2 feet long ... it would still be hideously expensive but it might actually be worth it ( unlike a 8 foot array )

you know yesterday i compared the pictures of Beyma TPL to the non-prosound pleated tweeter from Aurum Cantus and there is no comparison. the Beyma is on a completely another level. check these pictures:

Aurum Cantus:



notice the uneven pleating. notice the thin metal bars ( the magnets are proportionally small to bar thin-ness )



notice the perfectly even pleating and the thick metal bars ( magnets are proportionally large to bar thickness )

you can clearly see the difference in price even without listening.

which made me wonder - if consumer AMT is so inferior to prosound AMT - how good can a consumer true ribbon really be ? Aurum Cantus is already on the high-end side of things when it comes to ribbons ( obviously not when compared to RAAL )

the problem with RAAL is even though it has very wide and flat frequency response ( to like 100 khz ) it is achieved by using thin flat foil and large volume rear chamber which ultimately exposes the ribbon to being SHREDDED by any kind of loud bass from the woofers hitting it. i mean there has to be a reason why you don't see any true ribbons in prosound.

so i am not sure that ultra-thin flat ribbon is really the answer. maybe a bit thicker and corrugated is better. also i think the back chamber should probably be stuffed with some styrofoam to reduce the volume of the cavity by like 90% so that there is less air movement at low frequencies and the ribbon isn't ripped. after all i don't need the ribbon going down to 2 khz, only to about 8 khz.

i actually think RAAL placing transformer inside the magnetic structure is a bad idea because although it makes for a more compact driver and larger volume chamber it is now more difficult to modify the acoustical properties of the chamber when the transformer is sitting in there. i prefer outside transformer like in most other designs.

but outside of RAAL the Aurum Cantus was already the best built true ribbon that i know yet the build quality of their AMT is a joke compared to the build quality of Beyma TPL ...

so what is a bro supposed to use as a true ribbon supertweeter to mate to Beyma TPL200 at around 8 khz ?

would be nice if Beyma made a true ribbon but we know it will never happen. and RAAL replacement ribbons are too expensive. Fountek sandwich ribbon not loud enough to keep up with TPL and Aurum Cantus loud enough but looks like it was made in some basement.

should i just accept the sketchy build quality of Aurum Cantus and simply look at it as charming rather than unprofessional ? i mean considering it would only cover the top octave a compromise there is definitely on the table.

the Beyma TPL by comparison would cover a far more critical frequency range - one in which i am not ready to compromise.

when comparing Beyma TPL to Radian LM8K there is no comparison. the Beyma is much flatter response, much more efficient and with higher power handling to boot. and this is true even when only using it to 8 khz. in fact i don't see any other driver coming near Beyma TPL between 3 khz and 8 khz. not even the Eighteen Sound AMT, which costs the same as the Beyma.

but the Beyma doesn't reach 20 khz ... i just need to find the right True Ribbon supertweeter to use above 8 khz which is about where Beyma TPL200 begins to falter based on tests by Vance Dickason:

https://audioxpress.com/article/tes...a-tpl200-h-pro-sound-air-velocity-transformer



3 khz to 8 khz this TPL200 is just PERFECTION

Hello, not sure if this is in the correct section, but will be used on a full range driver, so here goes.

Easy question, can i use normal audio capacitors and resistors? ie 250v or 10w.

Maybe the hard one, what the hell is happening at the triangle symbol where a positive line becomes negative at point 2, then looks to become positive going to ground? Not too sure what the triangle represents, i think i understand the rest of it with a few more grounds than i'm use to.