I'm interested in building a DIY two channel, stereo, external subwoofer amplifier that can easily power up to two 12" subs at moderate listening levels. 200-300W RMS per channel? Balanced inputs would be nice.

I'll be using mDSP to integrate into my stereo system.

I'm looking for the ability to play around with different passive subwoofers in different enclosures mix and match with different speakers.

I've been looking at HypeX module's, icepower at PE, plus a ton of others and I have absolutely thoroughly confused myself.

I've never built an amplifier before so I would like something on the easier side, my electronic skills are limited to a few computer builds, a couple of sets of crossovers and general around the house/farm electrical work.

If anyone has any suggestions where to start, links to good proven designs, or any advice in general I am all ears.

Budget is around $500 or so, less would be great, more if necessary.

Thanks.

I have a SE triode headphone amp based 5687 actually with OPT air gaped so no output cap.

I want to use cascode CCS in place of OPT load, I have DN2540, IXTP 01N100D & LND150 so I'm looking for the best suited CCS for my needs: what upper or lower position device, etc.?

Also I need to use the OPT to reduce the output impedance but I have doubts if I need an output capacitor between the CCS & the output gaped transformer, if yes how can calculate the value?

TIA guys.

Hi,
So I want to restore the amp and PSU that I took out from an old Philips FWD750, I just want the aux functionality but I realized the aux inputs to MUX which send the signal and receives it back from another circuit board to communicate with IR sensors from the remote, I am planning to get the output without sending the signal to the other board just using the PSU and the main board. My initial Idea is to simulate the orginal layout in KiCad and try and get the output signals, however I can't find the Pspice model for TDA8920TH is the simulation neccesary or I can get the output just via inspection and changing or adding some circuit elements?

I have a pair of 12" Sears Silvertone cabinets that match a 6BQ5 Silvertone stereo receiver. They're nicely made as in they're furniture like and built to last, but they're pretty resonant, especially in the mid-bass. Rap on the cabs and the woofer baskets even give a pretty good ring. I'm planning on replacing the speakers with full range Fanes, but I want to at least get resonance down to kabuki speaker levels.

They're only one cubic foot, so I want very thin and efficient damping. I was thinking Peel and Seal and/or Dynamat stuff. I like the idea of self-adhesive products. And some fiberglass batting on the floor of the cab. Am I barking up the right tree? Are these even tameable? Any way to brace them without woodworking skills?

Hello all
So I know there are a zillion of topics about it but all being very specific and different from the one i aim to do, I am posting this thread. This time I dont want to go for a cheap option but more mid prices (budget 300 to 500). I have few issues I would need help with, which are as follow:
1 drivers:
I picked them according to qts, frequency range, fs and overall sizes and if i had the choice, design.
- 2 x DS-115-8 Dayton or DA-115 both 4"
- 2 x HiVi b3s midrange 3"
- 2 x Goldwood GT510 1"

2 cabinet
Horizontally stacked design with separate enclosures for bass of 25mm baltic birch plywood or maple
Size: h: 35cms L: 50 W:35
3 radiators

2 x 3" woox radiators

4 amplifier

1 x tda7492 upgrade to 2.1 later with a 4 output amp from Sure. Will bridge 2 channels with a xo to create a subwoofer channel

5 crossovers

Chinese stuff for peanuts according to answers here.

6 power and electronic

1 x dual VU meter
1 x UPS system with 12v witb 7000 mAh
1 x phone dock (optional)
1 x bluetooth receiver with usb and sd card
1 x battery charge meter
1 x odroid board (optional)

The problems/questions i have are:

If i dont align the speakers putting high and low together on each sides and mids in the center, will it have a big impact on the sound quality ?
Do i need to enclose the mids?
Can i enclose the bass into a sealed box with radiatore pushing out into a flat tunnel towards the side leaving the mids and high in the rest of the box in br?or ported?
Will it need bracing?
Is the volume enough?
Fastening using the factory screw holes or a pointy thingy pressing the driver against the bafflee


Thank you all for your help

I got more but it will come as i buid. I am not a full on noob I actually build speakers for over 10 years but passive and i just dumbly followed schematics and never bother with doing the engineering and all i self engineered i got super lucky it sounded decent (when it did... which wasnt too often)
Also, anyone knows a free program to mske a 3d model? Preferably pn Linux

Why to use 2 poles instead of one? On the contrary what people think , it has nothing to do with the stability, but the purpose is to widen the open loop bandwidth. Very grand majority of designers don't give any attention to this aspect, after all there are one thousand and one opamps with open loop bandwidth of few hertz and they have the reputation of excellence. So why to bother about open loop bandwidth?
The first aspect is to have a uniform NFB applied to the whole spectrum, same treatment to all 20-20khz without segregation.
The second aspect comes from tube amplifiers. In Williamson for example the OL bandwidth is 10khz limited by the OPT, 20db NFB is applied . With large OL bandwidth , on the transient of the input burst , the phase starts nearly what it will be on steady state . Whereas in very low OL bandwidth , it starts with -90° phase shift to reach gradually to that of steady state. This phenomena , provokes transient distortion if multiple voices burst at same time interval. To hear what I mean ,listen with a low OL the requiem of Verdi YouTube . With my aging ears I can clearly hear enhancement to 30khz OL bandwidth my be a sensation to 40Khz but above I don't think is necessary , but if can why not.
The VAS circuit that will be submitted to all kinds of 2 pole compensation techniques has OL bandwidth of about 4khz, to widen it to at least 20khz.



There are four different types of 2 pole compensation I found . TPC,TMC,Cherry NDFL and dadod's OIPTC. I will try all of them , and evaluate comparatively.
If you have suggestions to try out this or that , please be welcomed .
Hayk

I have just bought a pair of Aragon Palladium’s- the original version from the early ‘90s

Would just like to give them a small service with an adjustment of the bias current an a change or cleaning of the speaker relays.

I can’t seem to find any info anywhere about the alignment procedure - so I would be very happy if any of you could tip me on where to find the service manual ? 🙂

If I decide to change to caps in the power supply or maybe a full recap - what would be a good brand to buy and would it be safe to go 20-30% up in capacity?

Hi,

I have a simple SA9023 USB-to-Optical/Coax converter.
The story below is not too important though, I would need general understanding first

While trying to use the converter with Raspberry Pi I faced several USB related unstable "miracles", the converter perfectly/stably works with PC though. I suspect the converter EEPROM content is not consistent enough (there are some null string descriptors in there at least).
Maybe there is a chance to fix that, but looks like I just don't understand some basics to move forward. Would be happy if somebody could navigate me a bit.

So some general subjects I would like to understand, rather general than the device related.
Unfortunately I'm newbie with that.

1 A USB device has a chip (SA9023 in my case) and (SPI/I2C) EEPROM. Is there a way to access (read/write) the eeprom via USB. Or it could be only possible via a standalone programmer with a clip connected directly to the eeprom?
I know that some USB devices allow the underlying eeprom programming via USB registers. Sometimes it's briefly documented, but usually not.
Actually almost any USB device has a chip + eeprom, so the eeprom content (initial at least) population should be performed anyhow and it should be technological enough (for manufactures). It's hard to imagine a "man with a clip" in a factory.
Maybe there is just a common approach I'm not aware of. Or it's a vendor/device dependent "zoo"? The datasheets are typically silent at this point.

2 A modern USB device typically has a chip + eeprom. So there is a reason to believe the eeprom stores not data only but code for internal processor as well. It's hard to believe the chips are not universal enough as there is a lot of various devices based on the same chip.
However the datasheets include nothing about the processor, its type, commands set, internal registers, peripheral addressing, ports etc. Could it be it's just too common and well-known? So no information is available unconditionally and I'm just not aware of.
Anyway such firmwares were developed anyhow and (most probably) developed independently from the processor core, So the information should exists somewhere,
Could it be there is just a kind of "8051" processor inside and everybody know that excepting me? It's hard to believe every USB device manufacture creates its own processor to produce the device. Is there something to start reading from?

Thank you in advance

I have designed 3way home Hifi speakers
- inner net volume 150l
- 12'' woofer
- BR tuned to 22 Hz
- MTM
- 3 braces vertically (tolal height 1200mm)
- SPL 1W 1m 94db, RPM input power 120W
I would like to make the design similar to CANTON 1.2 DC but with only one woofer.

My idea is:
1. milling solid wood for front baffle 45/25mm hard wood
2a. 22mm MDF otherwise
2b or 20mm MDF + 2.5mm HDF (with some veneer)

It combination of solid wood with MDF (or MDF+HDF) good Idea or
make it completelly from solid hard wood?

Thanks for any suggestions.
Peter.

After cleaning up my office and storage I found some nice treasures.
I am not going to do anything with it anymore.

In total 100% original NOS Sanken 8 x 2SA1494 and 8 x 2SC3858 transistors

Will post to Europe and possibly elsewhere, PM me for details.

What frequency range tends to be most affected by internal cabinet reflections in a shallow enclosure for the Alpair metal line?

I am hoping cross over at 4th order HP @ 300Hz on an Alpair 5.2 and I am wondering if I am avoiding some of the trouble area or if the frequencies into the lower mid-range and above are most affected?

I am aiming for 5" internal depth in a wall-mount cabinet. There will be an LDW7 in the same cabinet but it will be in an isolated compartment.

Several years ago I picked up a used broken Sony Xplod amp Model XM-2185 GTX rated 165W x 2 into 4 ohms. Poking the volt meter around I discovered that the SMPS was still pumping out around +- 38 volts DC. But could not figure out what else was wrong with it. So I tossed it to the side for another day.

Flash forward to another day and I have a co worker who wants a cheap car audio upgrade for his newer Nissan Versa keeping the stock head unit. Well let's see what I have laying around the house: How about what I picked up a while back at one of Part's Express buyout/closeouts: 4 ohm Peerless SDS woofer Peerless 835004 SDS 6-1/2" Woofer 4 Ohm | 299-250 for like $10 each. Plus some tweets and a leftover crossover (I have active in my car) and I have half the problem solved.

As for amplification. Well, what can I do with the old Sony amp with working power supply? First, I got lucky and found the service manual: Sony XM2165GTX Service Manual free download,schematics,datasheets,eeprom bins,pcb,repair info for test equipment and electronics It's using a TL594 as SMPS controller feeding 6 power MOSFETS (FKV550N) 3 each leg. Specs on the MOSFETs say 50v/50A. Also from the look at the PC board and the circuit diagram, I could cut the board in half and have just the SMPS with a single row of the MOSFETs plus the two double diode rectifiers all sharing the one side of the heat sink/case. So I decided to cut the board and the metal case to provide heat sinking as well as protection. I also wired the +- DC output to what were the normal speaker outputs for one of the no longer used two channels. I'll post pictures of this abomination later. Yes, its pretty fugly. Edit: As promised, don't laugh:


(Above: Pic of split Xplode amp with SMPS power coming out front previously speaker terminals.)


(Above: Bottom view of SMPS with homemade plexiglass cover.)


(Above view of SMPS portion of XPlode amp) Soon to painted flat black and hidden.

Now I have power, what can I do with it and on the cheap? How about a chip amp? A little ebaying brought up a pair of TDA7294 boards assembled from China for like <$17 including shipping. Can't beat that!


So I've been wondering about heat sinking the chip amps and mounting the resulting mess in this guy's car. The solution I've come up with is building a shelf under the rear deck (in the trunk) to hang down at most 3 to 4 inches to hide the ugly SMPS amp and the chip amps. As for cooling, I have a big old CPU heat sink from a Dell that was being tossed at the office. Looks like:

I probably could put both chip amps on it, but I'm going to pick up another heat sink just like it (from ebay). So my plan is to have the old SMPS power supply on one side of the shelf and on the other have two of these heat sinks on their side with a 80mm (or so) case fan blowing thru the two of them. I also have a couple extra surplus big 'ole electrolytic caps like 30,000uF @ 50v to shore up the wimpy 3 x 2200uF per leg caps on the original SMPS board. Of course, mounted externally to the SMPS since they are kind of big.

My thinking is on most car amps the SMPS and all channels being amplified are all on the same heat sink/chassis. Splitting the SMPS from the amplification would reduce size (two smaller thingies are easier to hide/install than one big one). And the split would run cooler since the heat is spread and separated. Putting the chip amps apart from each other would also help.

I'll probably share this project with the guys over at DIY Mobile audio as well. I have a spreadsheet with the totals I have spent on this project which includes new 8 gauge power wire, fuse, ring terminals, 3 sheets of RAAMmat deadener. Total so far is under $150.

Hi .. I’m a Mechanical Engineer by trade , but interested in the DARK ART of electronics ..😕
I Currently have a valve audio system consisting of Audio Innovations - second Audio monoblocks , with Boarder patrol PSU’s fed from Series 1000 pre amp and Series 1000 SUT from my custom built turntable that is based on Lenco mechanics, and fed from a variable PSU that I built , albeit from a BOM and instructions.. My system sound great to me and I couldn’t be happier with it even after 8 years ..
however I like to build things .. and I would love to build my own amp ..
as always though I want to just straight in the deep end .. and I want to build something that I will want to use , instead of my AI set up , so it must look and sound as good or better ..

Hi,

I have absolutely no experience with DIY audio projects but have done plenty of 3D printing and am looking to try my hand at this.

Hi all hope you all are well?

I’ve just Recently brought Albarry AP4 + S508 preamp and power amplifier and I Really like it a lot, very
Nice sound,
The only one Problem is I can’t find any information about them or any specification,

Any help would be much appreciate,
Many thanks Matt

Hi Guys,

I have a query regarding the voltage rating for the output coupling caps for an aikido preamp.

I am not yet knowledgeable enough to figure out what voltage would be present at the output.

It looks to me like there would not be a large DC voltage present between the top grid and the bottom plate of v2 since the bottom plate is not exposed to the B+.

Based on this assumption it looks to me like a 250v k42y-10 cap would be safe for use here.

Am I dumb and/or wrong here?

Good morning

I’ve been looking at the unihorn design in Klang and Ton which utilises the seas exotic f8 driver. Is anyone aware of anyone on these forums that has built these?

All the best

Kristian

I know this isn't exactly Audio but It is in control of the source. This is the MCU for a diode matrix for keyscan in a Yamaha P-85 digital Piano. Multiple B and C key keys were dead. I have beyond doubt determined the missing signal to be on conductor n15 pin 23 of CN301. My problem now is that I do not know how to check for key return. I believe. I need to use my scope but I need advice.

Hi all,

I'n new to the group, recently joined to seek some information on my current project.

I'm in the process of rebuilding an old Pioneer SA-400 amplifier and am having trouble identifying the fasteners used through-out the unit. They're not standard metric threads, though the verniers measure the diameter of the 2 sizes used as 3mm/4mm. most of them are self cutting screws, but even the ones that aren't have the same thread.

They don't seem to be BSW or UN threads either. I've been down to the local screw shop and they are also unable to identify them.

is anyone able to help identify the screws?

thanks.

Hello,

What have been peoples experiences/thoughts on combining solid wood baffles with sheet good (MDF or Ply) boxes?

My 30+ years of woodworking experience tells me that such a large cross grain joint is a bad idea that can only end with the baffle splitting. Yet, I have seen countless examples of such construction posted on the Interwebs.

I know one thing that would help for sure, and that is "ripping and flipping" the wood, so you end up with a quartersawn baffle (of all the lumber cuts quartersawn has the least amount of movement).

Are people getting lucky?

Is it that we live in climate controlled houses where the humidity is fairly constant?

Has anyone, for example built a pair of speakers in Nevada (low humidity) and then moved to Florida (high humidity)?

Is it that the modern PVA glues that we use have some "give" to them?

Are there any guidelines people have used for how wide a solid wood baffle they would on an MDF/ply box?

Does the thickness of the baffle matter?

Any failure examples where the baffle did crack?

What about where the baffles were a glue up of layers of plywood? With this type of baffle, you would think there would still be movement as the layers are not constrained in their "thickness", just in their width and length.

What are your thoughts?

Thank you,

David.

I'm looking for a chassis with heat sinks that would be appropriate for a Pass A40 amplifier or one of a similar size or less. I have found plenty of nice offerings in NZ and east Asia but the shipping costs are prohibitive.

On my (long) list of projects to tryout there is the synergy horn.
So today I was searching for what kind of mid drivers would work in a synergy horn.
EBP should be as high as possible I think and the driver shouldn't be to big to get a good cross over frequentie.

So what would you guys recommend.
the Lavoce FSN030.7 doesn't look to bad I think. 3" and EBP=351
4 of these drivers will do something I guess.


Faital Pro 3FE22 doesn't look to bad either EBP=220




Then I also found the beyma 3FR30ND with EBP=324


That's what I found for 3" drivers.

maybe 4" could also be possible.In that case I found the following drivers:


B&C has the 4NDF34 with an EBP of 393, a decent power handling and Xmax also.

Then There is also the B&C 5MDN38 but this is already 5" and probably to big.


For the compression driver I am thinking of the PRV audio D290 as I had very good experiences with them.

For the low section I haven't decided the size yet. Will be probably 10".

Any advice is welcome

Hi .... I’m looking for some advice ( “don’t do it “ is not an option )
Some background ..
My current Audio system consists of Audio Innovations second Audio Monoblocks , with Bp PSU’s , fed by an Audio Innovations series 1000 pre amp , and SUT .. .. my system sounds great to me ... and I have been over the moon with it for the last 8 years .. but I want to build something myself.. it must sound as good , preferably better than My current system and have a visual impact .. so ...
I am thinking of another SE set up , with a separate PSU based around valve rectification ..
I have a pair of NOS 866a MVT Which I want to pair with 2 x 6ax4’s , this will give the visual impact ( well aware of the pitfalls of MVT’S )
Then on to the amp based on 300b’s .. . .

There are lots of amp schematics out there to use , it I cannot find a PSU schematic based on 866a’s ..

Has only one got anything they can share please ?

Cheers Brian

Hi

Ive taken apart an old oscilloscope and found some interesting old gold pin BJT and JFETS (and some opamps i havent looked into yet.
I have built a JLH 1969-ish clone before and a normalt simple BJT preamp, and been tinkering with electronics a alot, but not in audio very much.

But I would like to try this as an input stage to JLH or maybe a separate preamp.
It beaing a dual jfet should mean they are pretty well matched up?

It is a 2N5546 that a find most appropriate of what I have.
Link to datasheet: 2n5545-7.pdf PDF datasheet. ALL TRANSISTORS DATASHEET. POWER MOSFET, IGBT, IC, TRIACS DATABASE. Electronic Supply. INNOVATION CATALOG. Service


I have done alot of searching and havent found anybody using this, I read up on what resistors etc would be appropriate i believe. But what I just seem to not find any good info on is what makes a particular JFET good for audio purposes?

Is it even probable that a osciloscope jfet would be of any use? It was a crt oscilloscope but i dont believe it was part of that circuit but somewhere near the inputs.

Sorry if any grammar is messed up, english is not my first language.
Would very much appreciate some tips in the right direction.

Best regards,
Lars

This is something that I have been working on over the last week or so. The inspiration comes from an USB audio interface - a Tascam 2X2. The preamp section has always produced very subjectively satisfying results. It is also works well both balanced and single ended.

A while ago it one of the analogue inputs died and in order to fix it without a service manual I had to trace the circuit of the preamp section. For all of the Tascam marketing that made a big deal of the discrete, low noise, high gain, high dynamic range preamps it turned out that really it was a fairly standard mic preamp circuit. This inspired me to look into the idea of using a similar kind of circuit as the front end of a phono stage.

I have to openly draw attention to the fact that what I wanted was a relatively simple circuit. so I could have as much design input as possible. Also something quite flexible being both for balanced and un-balanced MC and MM cartridges without separate circuits for both. This would mean that I would have to have some compromise on outright lowest noise and distortion but I still wanted decent performance.

This is the circuit so far:


There a a few things that I still haven't wrapped my head around fully yet. One of these is he input transistors in parallel. I have gone to some effort to learn how to model the noise accurately in Tina and believe I have done this correctly. Paralleling 3 common garden 2N4403s in the LTP does seem to provide some small benefit and as it stands the circuit does seem to have decent S/N. I plan to look into other transistors in parallel, hopefully modelling these in Tina.





MC frequency response is pretty flat. The roll off at the extremes is intentional. Although these is content at these extremes I would argue that there is no musical content. I find that some roll off of lowest frequencies has a subjectively positive effect. Also I find that some roll off of the highest frequencies seems to help suppress pops and clicks a little.

MM response has a slight rise as you increase frequency but this is only around 192mdB and I doubt that it would be audible.

Distortion at VF2 and VF3 is 0.035 for MM and 0.045 for MC. What I have yet to work out is why it's around 9% at VF1. I have always had similar figures for other simulated phono amps that have worked fine. I guess I am not simulating the test properly.

The shown gains are not correct. This is caused by the inverse RIAA macro, which is based on a passive RC circuit.





Although I have designed the circuit overall I should mention that the input stage is based on an ESP Audio circuit which was uncannily similar to the Tascam circuit. However, I feel that I have done enough overall to call it my own.

I've yet to work out how to simulate the distortion properly for phono stages. It seems like the RIAA network throws everything off.

Also can't work out what caused the very slight deviation in the RIAA curve for MM cartridges.

I have my Alpair 7p sealed in a pine box with MDF for the front baffle, I have to buy a big sheet of MDF to replace the pine in the cabinet.
This sheet would be enough to try out some 1200x1200mm open baffles.

Before, a 500x700mm MDF open baffle sounded way too lean with the 7p.
The larger baffles would push the roll off point down an octave to 200Hz, which is gonna help a lot with that.
Will it be enough? not sure... I was totally satifisfied with bass quantity from the sealed 7p and the quality was excellent.

What are the implications of using a huge baffle like this, most importantly on the mids and highs? is it a waste of time? (assume more would do it otherwise)

Hi at all.

I bought a Hantek 6022BE osciloscope.
I am trying to measure THD but i cant.

I do not found the option for FFT function in the interface.

Hello everyone.

I have an ART Pro Channel mic preamp that has developed an issue that I'd really like to fix.

I've tried to be as thorough as possible, sorry for the long post.

Here's the problem:
When the Preamp Output knob is all the way counterclockwise or off and the Gain and Master Output are set to to 0dB (12:00, these exact settings don't really matter, this is just for example), the unit is quiet. As soon as the Preamp Output knob is turned clockwise, serious hiss (or "sshhhhh") is heard through the output. As the Preamp Output knob is turned further clockwise, the hiss gets louder and louder until the knob gets to 0dB or 12:00. Then, as the knob is turned further clockwise the hiss decreases until it is fully clockwise (+10dB) at which point the hiss goes away completely.

Also, if a sound source is plugged into the input, you can't hear it over the hiss until the Preamp Output knob gets to about 9:00 or -8dB. As the Preamp Output knob is turned further clockwise, both the input and hiss get louder until about 12:00, then the hiss decreases as the input continues to increase. When the preamp knob is fully clockwise you can clearly hear the input with no hiss.

One other interesting observation is that when the VU meter is set to "Preamp" & "Internal" via the 2 front panel switches, the dial immediately pegs hard right and no knobs have any effect on this.

I have attached both of the schematics.

Here is what I have done for troubleshooting thus far:

1. Visual/smell test. Nothing looks or smells burnt. None of the caps appear to be bulging or leaking.

2. I have swapped out all of the tubes and this doesn't change anything.

3. Measured the +/- voltage of A7 on pins 8 and 4. These are stable +/- 15V

4. I have measured the values of the Q20 transistor (TIP112). A youtube video suggested this is a common source of problems.
Base: 48.43V
Emitter: 47.44V
Collector: 61.03V

3. I have measured the input and output of the U1 Voltage regulator (L7815CV).
Input: 20.7V, Output: +15V

I would have done more measuring, but to get to the bottom of the main board, I have to completely disassemble the thing and make some sort of test fixture. I will do this if necessary, but I haven't yet.

I have also attached a recording of what the noise sounds like. At the beginning of the recording the Preamp Output knob is fully CCW. I then turn the knob fully CW 🙂03 - :10). You can hear the hiss increase then fade away (the hum is single coil pickup hum). Then I turn it fully CCW 🙂12-:16). Next I turn the knob clockwise after playing the top 4 strings on the guitar. You can hear the noise increase and then disappear as the guitar gradually comes through.

Finally, I have attached a picture of the front and inside of the unit.

It seems to me that the source of the problem is right after the Preamp Output pot and before the Compressor, EQ and VU Meter. This leads me to think that the most likely culprits are either or all of the following: C43, C48 (22uF 25V) and/or A7 (NE5532). Because the problem disappears when the Preamp Output pot is cranked, I'm leaning towards C43 and/or C48, but this is purely a guess. The fact that the input is clean when the Preamp Output is cranked leads me to think it is not the 5532, but again, this is pure speculation.

Does this noise sound characteristic of a certain type of component failure? Does it sound like one or more of the opamps is faulty? Does it sound like a faulty electrolytic cap(s)?

Would anyone be willing to take a look and offer some insight and tell me if I'm on the right track or completely out to lunch? Does anyone agree that C43,C48 A7 are the likely offenders?

If not, could someone point me in the right direction?

Any and all input would be greatly appreciated.

Thanks for looking.

Hi Guys, I write you because I wanted to know the true origin of this amplifier which is known Pioneer Amp here but I don't think so. It is very used for home audio in these places and its sound is not so bad but some improvements can be made to this amplifier for best performance. I leave the scheme which is in your hands and suggest about it. Thanks for your attention.

Anyone done a comparison of these two drivers run full range? While the NE149 is marketed as a midwoofer, the published response shows it is quite capable of fullrange operation.

The NE149 gets a lot of praise from multi way users as some of the finest midrange quality, high end SEAS and ScanSpeak reference from a drive unit less than half of the big boys which is what started my query.

There is a rise in the response of the 149 centered in the 8khz region on axis but I wonder if that can’t be smoothed out with baffle location? Is there any way to simulate that?

I do see the off axis response drops like a stone above 10khz but that’s perfect for me as I intend these as nearfield monitors

I do believe by the specs the 149 to be the better for LF extension unless someone knows otherwise?

Thanks again!

Still4given and I decided to start a new thread for those building the DX Blame MkIII, an amplifier designed by Carlos (destroyerX). Although there is an existing builders thread started in 2011, it has grown to almost 2000 posts long and is difficult to navigate.

New builders are encouraged to assist each other by reading through the original builders thread and posting relevant key information here.

I will update this thread index with links to the latest schematic, board layout from recent group buy, and latest BOM.

Original thread documenting the development of the DX MkIII:
http://www.diyaudio.com/forums/soli...me-mkiii-supercharged-will-soon-released.html

Previous builders thread:
http://www.diyaudio.com/forums/solid-state/193759-dx-blame-mkiii-hx-builders-thread.html

Recent group buy:
http://www.diyaudio.com/forums/group-buys/239084-blame-mkiii-hx.html

Byron and Terry's BOM (UPDATED 21-09-13):
diyAudio

I have never heard a beryllium tweeter, how close is the sound to a soft dome? It looks like to me on paper they are pretty close I guess without so much roll off.

Since were here a talking about tweeters, is there a major sound difference between a 40$ tweeter and one that costs around 200$ of the brand.

thank you diy guys.

After a very extended break due to ill health I'm finally ready to build my speakers.

Drivers are:

Faital Pro 15FH510 for bass: FaitalPRO | LF Loudspeakers | 15FH510

B&C 10MD26 for mids: B&C Speakers

Faital Pro HF144 for highs: FaitalPRO | HF Drivers | HF144

The room is as per the attached image (measurements in cm). Bay is 72cm deep? Speakers will be located either side of the bay window.

I'm hoping to split the frequencies at 200 and 1500 to start. Ill use a minidsp 2x4 to play around with to start and may progress to 2 2x4HD if i like the sound. Either that or start the laborious task of passive xover.

I have a 4 by 2 multicellular horn for the HF144 to start with. I'd like to play with other horns, JMLC for example but this will do to start

The 10MD26 will be sealed into a Nautaloss spiral as per xrk971 design - The Nautaloss Ref Monitor

The mid and high units will be firing down the length of the room away from the bay window wall. I would like to try them in the corners to start.

The bass is the only real question I have. There are two options.

Option 1: build cabinets to fit the corner (max WAF outside of option 2) and reduce the output to deal with the loading

Option 2: we are building a small booth (2 benches and a table facing each other across the bay) into the bay window. The seats could quite easily work as cabinets for the 15FH510 firing down the room.

I've included some enclosure sims for sealed and ported designs. I like the sealed as it gives extension at the loss of max achievable bass in the vented cab.

My system technics sl1200mkii with Denon DL110, various phono preamps, mac mini with various format music (minimum being AIFF 16/44), hifimediy asynchronous usb dac, B1 Korg, ACA of various types, Peter Daniels F5, MOFO and F4 to come.

I listen to anything, as long as i like it, opera to rock, techno to baroque, lone female vocals to concerts. I like to hear details (only if their in the recording obviously) the breath of the singer, the bow on the strings, skin on the strings.....basically the little things that make the whole. I love speakers that kick, sharp and hard and I'm not averse to loosing out on the lowest bass to get the tightest bass.

Hope this is comprehensive enough. Let me know what you think

First post.
I have a pair of JVC SP-95 speakers that came as a combo Kit for some unknown JVC equipment. Cheap speakers I know but there large 3 ways and ported with a 12 in. full range woofers & 1” tweeters, 3”mids. The tweeters & mids failed, they have been replaced with a Peerless tweeters 4 ohm & Goldwood mids 8 ohm. The woofers are 8 ohm also. I also re capped the crossovers with the same uf value caps that were originally on the crossover. The woofers & tweeters share a 1.5 uf cap & the mids use a 6.8 cap & both caps run through 2- 3.3 Ohm sandcast resistors. Pretty simple crossover. Problem is the tweeters are not bright enough & the mids are almost nonexistent, l can’t hear the mids. The woofers work great, lots of bass response. I made a mistake using 4 ohm tweeters, would they improve if I replaced them with 8 ohm tweeters? What kind of cap would bring the mids back to life, the 6.8 cap isn’t right for them. Some kind of ball park uf value for the mids would be great to know. Thanks for any info.

Nevermind

After a few years of researching different designs, including the monkey box classic 3-way, "cornscala" builds, and the beyond the Ariel design, I decided to try building a synergy horn. With the help of the excellent synergy calc spreadsheet by Bwalso, I got the confidence I could actually build these. There are many others to thank for their contributions to the other various synergy threads such as Weltersys, xkr971, Patrick Bateman, Mark100 and others. And I can't forget Tom Danley for sharing his insight on his brilliant design.

The start of much sawdust making...

I was given this amplifier from a friend of mine who is moving.

I hooked it up today and there is no sound from the right channel.

I am not a DIY’er by any stretch of the imagination but I am wondering if there is an internal fuse that can easily be checked? Before I bring it to an expert?

Any help you can provide is most appreciated.

SB Acoustics SB16PFC25-4 Woofers, BNIB

$29 USD per pair 😱

More Info & Spec sheet available here: SB Acoustics SB16PFC25-4

Hi,

here is my take on simple low power 5W class A amplifier. Inspired by ACA I wanted to have lower distortion and higher damping factor then ACA.

Amplifier sounds better than ACA. More resolution, more dynamics, better bass.

Happy listening!

I see a post from 2013 which is basically the same question. But a lot can happen in 7 years.

I have some of the wood cut for a pair of 5 cubic foot (gross) sealed cabinets. The interior dimensions are 20.5" cubed. I will be mass loading the top, sides & bottom of the cabinets. 1-1/2" baffle. Perhaps some bracing for the rear, which will depend on whether I use a plate amp or an eternal amp. Interior will have a liberal amount of Rock Wool.

The project is "designed" around the Ultimax 18. However before I bought the drivers I thought I would see if there were other drivers I should consider.

The main purpose is to deliver wooferage to my 15'x25'x9' HT room. My fronts are full range which I high pass at ~30hz. To be more precise my fronts are Magnepan MMGs sitting on top of a pair of GR Research OB "W" 12s. They will reach down to below 20hz, but when doing HT, at a reasonable volume they will occasionally make a nasty cracking sound which I interpret to be them bottoming out.

I alleviated that by raising the High pass. I never have a problem with any music.

So I am building these subs to mainly do infrasonic to ~40hz. Is there anything in the price range of the UM 18 that I should look at?

Having, as most of us, found myself with a lot of free time on my hands, it seemed a perfect opportunity to finish a project that I started about three years ago.

General advice for building a valve amplifier is to start small, ideally using a ‘make-your-own’ kit. I have not done that. Not even close. I’m kicking off my sojourn into homebrew audio electronics with a 100W bass amp using Partridge transformers salvaged from a Carlsbro TC100, with a circuit and chassis of my own design. This is my second attempt at this undertaking. The first edition has sat untouched on my desk for the past year serving as a fluctuating source of agitation that would peak when upon watching my ex-girlfriend’s eyebrows reach escape velocity when I told people that I was working on it. Yes I’m ******* building it Jenny.

Here's the design:




Everything before the phase inverter is likely to change as I build and test, so pay it little mind. This post will mainly be my reasoning for the power amp and power supply. It's a bit of a wall but I find it useful to write out my thought process. I've mainly followed Merlin's methodology for designing a PP amp. I welcome you to point out any daft mistakes. I'm a first-time builder diving into a project way beyond my ability level. It's an inevitability. I have already highlighted three queries that I would greatly appreciate assuaging.

I have actually started buidling the amplifier; it's just taken me this long to get around to writing up this post though I'm not too far along to not be able to adjust the design so again, I ask for your honest critique.

Naturally I don't have any information on the transformers. But I do have a variac and a multimeter... The average voltage ratio was 17.6, the square of which, 311.2, is the impedance ratio. Given that these measurements were taken from the 16 Ohm output tap that gives us a primary AC impedance of 311.2 * 16 = 4980R which we can safely round up to 5k.

My mains voltage today was a toasty 236.5 Vrms, which presented on the secondary of the power transformer as 357.2 Vrms. Once converted to DC by four UF5408 we should have a HT voltage of 357.2 * 1.414 - (2*1.7) = 501.8 V however the measured voltage is actually 494 V. Any ideas? The amp that the transformer comes from has a HT of 470 V so the measured value is closer but still much higher. Is this because I've taken the measurement with no load applied? When taking the measurements only the bridge rectifier and reservoir capacitor were hooked up. For the time being I'm going to assume a HT voltage of 480V as it's a happy medium between the HT used in the amp that the PT was pulled from and the measured voltage.

The impedance 'seen' by the tubes in each class of operation is therefore:

Class A = 480 V / 2500 R = 0.192 A

Class B = 480 V / 1250 R = 0.384 A

I spent far longer than I care admit wondering why drawing load lines using these values put the operation well outside of the EL34s maximum thermal dissipation until remembering each side of the power amp has two EL34s in parallel. They each supply half of the current!

The maximum thermal dissipation at the HT is 25 W / 480 A = 52 mA. I'm aiming for an initial biasing point of 75% of this which is approximately 40 mA. This necessitates a bias voltage of 20V. Which brings me to question two - the schematic for the TC100 shows a bias voltage of -37! which seems way too low. Am I misreading the schematic? Could I take from this that my measurement of the OT impedance is incorrect?

The current flowing in the screen-grid dropper resistor will be the grid current of the four EL34s plus the preamp valves. The datasheet suggests a 20:3 anode to screen current ratio, so = 40 ma * (20 / 3) = 6 mA screen current per EL34. The preamp valve complement is an ECC832, ECC83, and ECC81 with respective typical current draws of 20 mA, 2.4mA, and 11.7 mA. The total current through the screen-dropper is therefore (6 * 4) + 20 + 2.4 + 11.7 = 58.1 mA. This is a fair whack of current so I've chosen a small dropper value of 100R to limit the voltage drop to 58.1 mA * 100R = 5.81V.

The screen stopper resistors are 1k so they will also drop 1k * 6 mA = 6 V. The final screen voltage will therefore be 480 - 5.81 - 6 = 468.2 V, a good 18 volts above the EL34 maximum screen voltage of 450V. Is my HT too high? Do I need to increase the size of the dropper resistor to drop more voltage? Or can I leave it at this value expecting the voltage to sag when under load?

That is it for today. Tomorrow I'll start posting build progress pictures. I'll be including any mistakes and how I managed (or failed) to rectify them for both educational and entertainment purposes.

I'm trying to get enough power to bring an acoustic bass guitar to be heard with acoustic guitars. I'm thinking of the Smokey amp plugged into a 10" speaker mounted to the inside back of the guitar and maybe opening up a port hole or even an f hole on the front. Just enough to raise the db level from unamped at around 60db to 100db. Any thoughts?

I am thinking about building a Champ 5C1 clone based on a schematic mod I found which added NFB to the circuit almost like a gain pot. There was an audio file where he played the amp and demonstrated it and I got the schematic from him a while ago. I want to build it so I have multiple tube options as listed in the attached schematic.

Before I dig into this I wanted to see what you all think about the viability of this, I assume they are not all simply just drop in replacements, even though I see them called equivalents, and some switching may be necessary to set bias and other levels appropriately.

Hi,

I have this idea of using a JFET as a Phono Head Amp for my MC Lyra Lydian cartridge (500uV).
Currently I use a Musical Fidelity The PreAmp A3 (shunt power regulation, LM394 BJT matched pair head amp, and VQ1000J MOSFETs), and I want to beat it.
I know that one AD797 IC as it is based on BJT's can give better S/N ratio, but I don't like to see so many transistors in the signal path... I want a minimalist design.
And why not mix JFET with Tubes?
First time I saw this design was in the 90's from Sonic Frontiers, when I used to buy quality components from The Parts Connection.

So, I share here the Sonic Frontiers SFP-1 Phono Stage schematic (partial, due to upload space constrains) so you can comment on it.

The JFET in use are marked as J310. Anyone have information on this one?

+B1 AND +B2 = 210VDC (for the 12AT7 output tube and 6DJ8 RIAA driver)
+B3 = 187VDC (for the JFETs)

.

Cheers.

Hey there good people,

I'm wanting to build a circuit for live use for vocals, and looking for some suggestions.

The gist of it is basically, I need something with a microphone input (it'll be used with dynamic mic), then feeding an effects return/send which will be hooked up to guitar pedals.

Would like to integrate a wet/dry blend knob in.

Lastly, feeding a mixing board, so line level output.

As of right now, I'm looking at the THAT Corp chips for both a preamp, and line driver output.

I'd assume the mic signal coming in needs to be boosted via preamp to an instrument level, fed to the effects loop, then converted to line level.

Do I need something to make up the gain after the wet/dry blend?

Open to all suggestions. All this running on a 9v supply would be ideal, but beggars can't be choosers, so open to anything.

I have seen that some stereo amplifiers from the 60s have a central channel, such as the Fisher X101D, or the Scott LK79, among others.
I know it is a connection between the 2 secondaries of the output transformers to run a third speaker called the center channel, I have seen the circuits and understand it, but I would need someone to technically explain how it works.
Thank you so much
Gusmore

Hi

After a long break from the project I want to push it a bit further toward a finalized design (who am I kidding? - like I would ever really finalize/finish anything..).

Design-goals:

• Input-voltage: 230Vac+/-10%
• Output-voltage: +/-60V, +/-30V and 12Vdc for a fan
• +/-30V can be configured as regulated or un-regulated.
• Power: enough for a single-channel classD-amp @ +/-70V with 4Ohm Load
• Dimensions: max: 100x100mm pcb
• Standard doublesided 35u PCB
• X-former: ETD34-size core from typical ATX-smps.
• Option for external inductor and split-capacitor for the LLC-tank
• Prim-sec isolation: min 250mils = 6,35mm
• Isolation-distance at HV-side: min 100mils
• Controller: L6599
• Regulation: TL431
• Cooling: minimal airflow. Preferebly no forced cooling for normal operation with 8Ohm load at amplifier
• Disable-input that shuts down the PSU with an isolated 12V input
• Option for external 12V for L6599 in R&D
• Temperature-shutdown if mosfets or transformer gets too hot.
• Designed for amateur hand-soldering.
• All passive SMD are 1206.
• Dissapation in 1206 resistors below 100mW
• Option for over-current-protection: splitcap and/or cap-voltage-sens

Inspiration:
http://connexelectronic.com/wp-content/uploads/2017/09/SMPS500R.pdf
https://www.st.com/resource/en/datasheet/l6599.pdf
Power inductor tester

Transformer:
Its a massive headache to design and construct the transformer so that it works AND is safe to use.
I know that commercial options are avalible, but: a)Whats the fun in that, b)I could not find one that fits my design-goal.
Please dont even consider building something like this without building a test-rig to verify inductance AND saturation-current (see link above)


Earlier post regarding this project can be found here:
Mosfet failure analysis
Heating in LLC HB mosfets ?
Power limitations for LLC-smps for amplifier
LLC simulation
Heating in LLC transformer

Tests performed to verify design:

• Measure hotspots under load and no forced cooling (Xform and mosfets)
• Measure voltage-drop and stability at output with pulse-load of 8ohm from Vcc to GND (roughly 8A at 60V)
• Multiple on/off cycles at mains power with and without load
• Limited noise from speaker with amp and speaker connected to PSU

Design questions for you all:

• Is it OK to have the Ycaps before the CM-coil at the input?
• Do you see any fatal design-flaws?

Pictures attached: First prototype on a double-sided PCB and suggested updated design-files.

Disclaimers:
This design is NOT a commercial design for sale. I'm thinking about offering the design-files for free here. My only worry is that a project like this is potentially dangerous and it will require some skill to assemble a safe unit.
You can buy a perfectly good commercial powersupply! This project should never be build if the only motivation is saving money. While the parts are cheap its very labor-intensive to build and test.

I want to do distortion measurements and spectrum/frequency analyses of amplifiers. Mostly you have a 1.0 kHz test signal and you see the overtones at 2.0, 3.0, 4.0 etc. kHz. But I want also to test amplifiers with a 20 kHz sinus and then you get overtones at 40, 60, 80 etc. kHz.

As I see in the pictures, audio analyzer software represents frequency spectra just untill 20 kHz.
Which audio analyzer software can represent frequency spectra above 20 kKz ?? Let's say untill 80 kHz?
Of course under the assumption that you use an audio soundcard/DAC with a sample rate of 192 kHz. The better ones do so.

And which audio analyzers are the best for doing measurements on amplifiers?

I own the MSB link dac III and plan to build the upgrade power supply. To connect the power supply with the dac unit it need the power connector in the picture.

Does anyone know where can I get this type of connector? or what do they call it?

Thank you for every help.
Tanwa

Hello friends,
I had a lucky and i buy NOS cdm1 se, those speakers was never been used i open them at the first time this week.
my question is if i need to replace ferrofluid in the tweeter because this speakers is 20 years old, new but 20 years old.
BTW they sound amazing
thank you 🙂

Hi guys ,can you help make recommendation on a budget-friendly 100W-200W home hi-fi amp which is happy driving 3 Ohms.

I need one to drive a pair of Alon IV. I don't mind a DIY or any off shelf solution as long as it's works.

Hi, This is my first post since '04, when I posted a few questions under the name John no nfb, I quickly realized I didn't have a clue what I was talking about, so went back to lurking, anyway fast forward, I still don't know what I'm talking about but now I just don't care if people think I'm stupid! My question is- I would like to see if I can use a TFK RS288 indirectly heated pentode as a transformer / choke loaded cathode follower ( a linestage) really I need to know what cathode resistance to get about 25mA through the device, I plan a floating screen supply, so no screen current through the trans/choke, I will attempt to post some specs and a rough idea of a circuit. Thanks John

CONNEX SMPS 300RE SWITCHED MODE POWER SUPPLY +/- 45 volt with 12 volt auxiliary.PERFECT FOR HYPEX AND OTHER PROJECTS. £40 plus postage.

I found old parts on their listing but I don't know if they have good reputation.

Any customer on this forum ?

Hi,
I have a set of pretty much mint ATC SCM11 speakers that I am just not using. Figured I should sell them on.

These are the latest versions, in original packaging with all grills, dust bags etc...

Marks from spike mounting on stands on the bass (not too bad) and a couple of very (very) minor marks elsewhere that you really have to look for. On a set of stands, they look brand new.

I can provide pics on demand but if you want to see them now, you really could just download a stock image. Aside from remarks above, they look that new 🙂

I'm based near Edinburgh. Happy to arrange posting but only in the UK.

Looking for £900.

Cheers,

iep

Hi All, I hope everyone is staying safe.

I'm restarting my effort to build a subwoofer after pausing my research to move.

For experimenting with Hornresp, I picked the Dayton Audio Rss265hf because I've seen it show up a few times here. I then set about finding the ideal box volume to achieve a Qtc of 0.707 based on this website. I figured I'd use the equation linked there:
Vbox = Vas/((Qtc/Qts)^2 -1) and graph it to figure out the range of box volumes I can work with (Graph attached at bottom).

[Edited this section for clarity, so I don't sound like a madman]
In the end, it seems like I must to construct a box with a volume Vb = 1.28 ft^3 (which is below Vas) in order to achieve a Qtc = 0.707. Does this make sense? Can I make the enclosure smaller than Vas?

A couple other questions, that I haven't been able to find answers to:
1. Why is the range of possible volumes so small?
2. Are there any glaring flaws in my approach to this?
3. Can hornresp help me sweep all scenarios?
4. Is it all moot?

Any help would be appreciated.
Thank you

What is it in an amplifier that makes it better to control the base?

I'm building an active three way, and currently I use LM3886, but I what my speaker to do better. I have a clear idea on how I want to do the amplifier for both midrage and tweeter, but what about the subwoofer.

I havn't measured the impedanse of the subwoofer, but it's a 4 ohm driver (SB23MFCL45-4) with two passive radiators, so I dont expect it to be easy.

I have four pairs of MJ15003/4 and I intent to use them in the amplifier. I have a choise between 2*18V/6A or 2*25V/6A trafo, but I rarely play loud.

Questions: Do I go for the bigger trafo to get more headroom?
Do I aim for lots of open loop gain and thereby lots of feedback, to get very low output impendance?
Or do I aim for the ability to (in theory) drive 1 ohm, to be shure to have current enough?
Og do I aim for low bandwith in order to make the fase margine in the "safe" aren to make it more stabile?
Do I aim for higher idle current, in order to output stage more linear?

Anyone seen Rush pairs used like this?

It is balanced in and balance out. Could be unbalanced in (by grounding one input) or a phase splitter (one input grounded and two output each wrt common).

Unlike the normal Circlotron this one has voltage gain, effectively common source.

Like a normal Circlotron it is symmetrical so even harmonics cancel. The p-channel and n-channel differences cancel -- you don't need to use well matched complements to get low 2nd harmonic distortion.

It can be biased for Class-A or Class-AB. In Class-A it approximates square-laws so the bias current can be about half that of standard push-pull Class-A with smaller heatsinks and transformers and caps. It can be used as a no feedback amplifier with current drive output.

In Class-AB there is an optimum bias for minimum crossover distortion, it is quite high bias (since there are no source resistors) giving low distortion over the first watt. It can be used as a no feedback amplifier with current drive output. The attached plot is with 300mA bias and 25V supplies giving about 0.01% THD at 1W/8R.

The bias current for Class-A or Class-AB needs to be stabilized with Vbe 2 multipliers (or thermistors) to prevent thermal runaway.

Best wishes to all here for 2020 and beyond.

Cheers,

I have a volvo s80 2004. I am going to install a Soundqubed hdx315d1 in the trunk. I would like to have as much sound as possible, but still have it playing down to the 20s and up to the 80s-100s.
I am going to make a new trunk floor from plywood, and build a ported box from plywood with a slot port tuned to maybe 29hz?

I do have an 8" aeroport, but it is too short.

The trunk is quite small and i could barely fit a rear firing box.
Should i make it rear firing, both sub and port. Side firing port. Sealed off firing forward. Or firing up?

I bought a new 1228 110amp Curtis controller for a Mobility gopher then found I will have to program it to make it go faster, etc...? A Curtis serial programmer costs an arm and a leg to buy so I went with a UART although I have no idea on how to set it up except where to plug it in on the Curtis 4 pin Molex, Ground, Transmit and Receive plug. The fourth pin is NC. The Curtis controller module is self-powered 24v and 5v for programming, the UART has a computer style jumper for 5v/3.3v? I need to know if I take the jumper off and if I just connect the Ground, Transmit, and Receive that would be it? Or does the UART need the 3.3v to power its self? I downloaded the Datasheet to look at and uploaded some photos of the UART serial programmer.I want to avoid any mistakes if I can help it? FT232RL%20USB%20UART%20I.C.%20datasheet.pdf

I have two sources, one offering NOS Harris semiconductor and the other selling up to date Central Semiconductor transistor.

Obviouly, my question will be, witch one do I choose ?

I've recently gotten back into woodworking and seeing so many great DIY speaker projects online/youtube and well... my small basic Sony 2.1 soundbar has worked fine for years, but I think time to upgrade.

Because of the room, I'm looking to build a 2.0 or 2.1 system. My seating is against the wall so, no space for rear speakers... also an opening on either sides, so rears if I forced them in, would be a foot from my head, and not wanting that.

Just looking for ideas/suggestions on what I would need for this build in terms of power.

I like my setup now, because TV plugs into the soundbar, and my TV remote adjusts the volume. I don't have a big receiver, lots of wires, a separate remote, etc....

Looking for something that works the same and with just as simple of a setup. Not looking to spend thousands on speakers and electronics... something a bit more entry level that's at least better than the Sony I have now. I see a lot of DIY speaker plans online... but all are just speakers, maybe crossovers as well, but nothing about power.

Any suggestions? Can it be done where the TV volume on the remote adjusts the volume? My soundbar now does it, but it's also connected via HDMI... not just a straight amp with audio jacks.

Hello. I am looking to buy a Dynaco PA-774 power transformer.
Thanks,
Steve

hello someone could help me with the value of the resistor r311 has a 10k but they already changed it I don't know if it is the correct value

I've been reading about these cartridges & am somewhat surprised that there does not appear to be much discussion about them. - (I may be wrong here of course).

I'm considering dipping my toe in at the lower end - up to about US$1K, & would appreciate any advice re their performance compared with other similarly priced units, say Ortofon or AT. etc. - (Properly set up of course).

I'm considering the Otello or the Carmen models but would welcome comments if there is a big difference to be gained by going a little higher. I also have a very low mass uni-pivot arm lying idle which may come in handy.

From watching some of Peter Ledermann's lectures, I was impressed.

As an electronics engineer, special preamps, cartridge loading etc., are no problem if needed, and realise that they generally need a bit more gain than the usual MM preamps & hence more attention to lower noise. - This could be an interesting challenge. I also have a very low mass uni-pivot arm lying idle which may come in handy.

As an amateur chamber music wind player, my taste is classical from small ensembles to the major works including pipe organ and, (strangely ?), I tend to listen to the music & not the equipment !

Any suggestions appreciated, - thanks.

Zener designated ZD1 on the main board is shorted.

Best I can make out is 1N739A.

There are 2 of these zeners servicing the output driver board it looks like.

Hi. I have to repair a philips 22Ah380 amp and its 22Ah280 pre amp. With all the flat controls, comparing the set to any built-in amp, it sounds bad, lacks bass, I think it should sound much better. I test it with 8 ohms resistive load and signal generator and the response is flat, even beyond the audible range. I did a full recap on the preamplifier (electrolytic only) without any appreciable change. The amplifier had a previous repair, originally it has 2 pairs of transistors per channel, now it only has one higher capacity pair, 2sc5200 / 2sa1943. Can this cause the bad sound?

I just build 2 of this circuit on a prototyping board, the one with the holes pre drilled, but instead of 21x gain, I used 11x, 33K as Rf and 3.3K as Ri and a ceramic 100nF capacitor in parallel with +Vcc and -Vcc.


I'm using a record player with a RIAA preamp, still on breadboard, and the gain of such preamp is about 100x @ 1Khz. which means about 500mV overall. Sometimes both channels work, but most of the times just one works, and there is a hum on the other speaker being fed with the not working channel, probably 60Hz. When one of the channels ist not working, the postive supply voltage drops upon not feeding the power amp with the signal comming from the preamp on the working channel, it drops from 23V to about 17.5. The negative supply doesn't change. Any sugestion on what could be the problem?

Additional info: As I'm trying to build a 4 channel amplifier, both LM1876 shows the same issue. I also jerry rigged grounded the whole system using a bike spoke and it does make a difference, when it's not grounded the 60Hz noise is stronger. I also tested the RIAA preamp, change the channels into the LM1876 and both channels of the preamp are working, the issue seems to be on the power amp.

Hi,
Am in the process of setting up on breadboard a point to point wiring of a Aikido pre amp with power supply. Will be doing P to P wiring for assembly. Anyone with photos of layout of components would be greatly appreciated.

Thanks again

Joe

Fellow Raconteurs,

I have a Woodside CD Transport (Philips CDM1 Mk11) without a remote. I believe a Philips or Marantz remote of the same era will work with it. Any advice on required remote will be greatly appreciated.

Good day

I need some guidance re above. On the boozhound website it says the volts is from 12 to 24v. I would like to connect 2 x 12v batteries in series in order to get 24v.

However, once I have charged the one 12v battery, my volt meter reflects 14v.

I suppose the above is normal, this will mean in the end I might sit with 28v total feeding into the phono stage which is to much. Can I perhaps use some type of resistor to rectify the total voltage?

I appreciate the assistance!

Wondering if anyone has a pair of SJEP120R100's collecting dust on a shelf. I'm very interested in trying these in my Babelfish J2 boards. Thanks!

Hello!

There are lot of info spread around in different topics about those drivers, I will post all my questions here in one topic.

1. I only want to build a sealed cabinet not vented. I am after that "old school" 60's "huge/live/open" sound and feel.
2. One option is to build something similar to this: Fane 12-250TC Retro Speaker. - Page 2 - audio-talk Has anyone built something similar but with 15 inch driver?
3. Someone here in diyaudio said that to hear the difference between 12 and 15, the cabinet for the 15 needs to be at least twice as big, for example 225 litres. Is that true? What f3 would 15 incher achieve with 100L and with 225L sealed cabinet? I read somewhere that 12 in a 80L sealed cabinet gives f3 around 64hz.
4. How much does cabinet shape affect sound with drivers and enclosures this big? I would like to build something higher and thinner, is that a bad idea?

Apparently same as RX-V681/RX-V781/RX-A760/RX-A860

Everything working fine when plugged in and turned on.
Output voltages on all speaker terminals are few mV.
As time goes by (10-20 minutes), FR chanel goes to 10mv>100mv>200mv>300mv and up to 3V and then PROTECTION kicks in.

Very strange issue. Can't find anything blown/overheating/shorted/open.
All diodes and transistors checking out OK. Resistors too.

Can't find service manual or schematic....

Any help is greatly appreciated.

Please see attached part of the schematic. This is a delayed turn on and protection circuit for an SS power amp. There are two electrolytic capacitors, 220uF and 470uF. Before repair, the 220uF cap was completely dead, showed 0uF and many parts such as surface mount resistors were all burned out around it. I replaced the bad parts, the amp now turns on and off properly and performs as expected.

But these two electrolytic capacitors get very hot. Too hot to the touch. Beyond 60 degrees Celsius. I’m assuming this heat is what caused the original cap (cheap 85 degree Lelon) to fail and take out the circuit. The new caps I put in are 105 degree Panasonic FR.

Any idea of why these caps are running so hot by looking at the section of this schematic? Any help or advice is appreciated.

Think I'm going to integrate this little display into my next project to monitor the current for each of the output tubes. It's Arduino based (of course) and plan to add some relays for overcurrent protection. The board will have the sense resistors so you just have to run a wire to each cathode and then one ground. Power will come from a small isolated DC/DC converter so no worries about voltage level issues. Maybe use a few jumpers to set the overcurrent limit.

Now I can already tell that some monocles have fallen from peoples faces at the thought of a microprocessor being near their tube amp

Is there any interest? I don't have a pcb layout yet as I'm still working on the details.

Hi,

There is a chap selling these OTL amps, please open link, they would be perfect for my Altec Valencia speakers at 16 Ohms. The designer seems to have done his homework.

I'm wondering if my Klyne Series 6 solid state preamp would be a good match for them. The Klyne owners manual does not provide specs.

Please advise.

OTL Amplifier Stereo Pair 20 Watts w/8 Ohm Load, New Quality Parts & Assembly. | eBay

I came across this thing recently and thought it would be a cool project to fix up and maybe come up with some mods. It's a really solid box - all tube, nary a transistor in sight! In one box I can get stereo spring reverb (really, with 2 separate tanks!), and maybe just use it as a stereo tube saturation/distortion too. Mine has super weak signal so I figure a bunch of the old Suzuki oil-filled caps are bad. Got some replacements in the mail.





As I've been digging into it I realize that there may actually be a third effect it produces: some sort of stereo field widening scheme. Take a look at this schematic I've annotated:



Notice that the Blue and Pink nets go between channels, doing some sort of cross-feedback thing combining each dry signal with the opposite wet signal. It's further complicated by the negative feedback from the reverb tank drive output back to the cathode of the first stage. I'm trying to figure out exactly what is going on here:

1. The Green and Yellow nets are negative feedback, right? Just like a Champ 5F1 - even has the same 22k resistor! Just wanna make sure I'm understanding this right.

2. What's up with the caps parallel to the attenuation resistors on the Blue and Pink cross-feedback nets? C13 and C14. I guess we want the full audio signal to carry, but only an attenuated DC voltage?

3. I'm having trouble understanding how the Blue and Pink cross-feedback lines interact with the negative feedback lines and the input signal on the first triode V1A/V2A. Which direction is the feedback going? Is the V3B/V4B cathode driving or being driven? I would think being driven because there's no other way for a dry signal to reach the outputs, but what causes this to be true?

4. If the Blue and Pink lines really are driving the V3B/V4B cathodes, that would mean we're putting an out-of-phase signal from the opposite dry channel on each wet output stage's cathode - positive feedback-style, but not the same signal, just a presumably "similar" signal if it's normal stereo music. What are the implications of this? Do we get weird stereo phase-cancellation stuff? Is this the origin of the stereo-widening effect? What are the effects on mono-compatibility of the output?

I'd appreciate any help y'all can offer! I'm pretty handy with electronics, but not any sort of expert on tubes or too complicated of analog stuff. I'm planning on installing a switch to optionally disconnect those cross-feedback lines to get wet-only outputs, but I'd like to keep the option as part of the unique sound of the unit. I just want to understand what's going on!

Thanks!

Does anyone happen to have a clear photo of the power supply drivers area?
C219:
R62:
R61:
R62A:
R61A:

Does any one have a schematic for a circlotron amplifier using NPN power transistors in the 10 -15 watt region
Over my 50 odd year career in amplifier building I have tried most schematics but not this one
Not wanting Fets or exotic devices
Trev