For Sale : Unbuilt DIYAUDIO store original V1.0 Amp Camp Kit with beautiful Black Red Chassis. This is a complete Kit with PCB/Components/Hardware and Power Supply - photos show one but the other one is also included in this sale. You can modify the kit to match the present Version higher output and it will require different power supply

Picture of the kit for sale. Prefer US sale as it is easier to ship but willig to ship world wide. PM me for price / shipping etc. I spent 296 USD and expect that as a base price plus shipping/paypal fee

Hi,

looking for a Denon PMA-850 MKII.

Thanks.

🙂




(Yes, I know [emoji6] )

I just spent a while re-building 4 sets of interface for my 2+2's.
I went through all the mods I've seen here, the C-mod, a high voltage 0.22uf across the zener string, different values of final output resistor, from 100M to 500M.
The original design was just about spot on, all the latest "mods" dont really do much, give it a bit more tizzle if anything, which some will interpret as detail.
Even the original design with the 220uF crossover cap is pretty good, ( replacing the 220uF with a new piece brings it back to life, maybe the tales of it being necessary to replace with polyprop cap aren't exactly true)
A refurbished interface is about as good as you will get, whether its the old 220Uf design or the C-mod with 47uF polyprop.

BUT, there is a way to get a drastic improvement in clarity, open-ness, bass tightness and all round musicality, although in theory it shouldn't work.
Separating the inputs to bass and HF transformers, ie, providing two sets of speaker connectors and using two sets of amps, one for bass transformer and one for HF transformer, really makes the Acoustat a superb loudspeaker (which it already is, but now its even better.)

Now I know that the two transformers get blended at the HV section feeding the panels, and I agree that bi-amping shouldn't make any difference, but it surely does, and I just cant listen to the single amped version now.

I'm using very powerful amps, so I dont think its just a matter of doubling up with power, maybe it is, but whatever, if you get a chance to try this its very worthwhile.

But having said that, I have enormous respect for the original design and dont want to infer that there is anything wrong with it.

For me, bi-amping is the ultimate way to listen to Acoustats, despite my brain saying it shouldn't be so.

Hi guys.. welcome comments, remarks, suggestions or criticism of the wiring diagram for TDA 2003 chip amp in bridged mode. I am not the author, just a long time ago, I redrawn the wiring diagram on a piece of paper, the author was of German origin ..the wiring diagram was published in the magazine Hobbielektronika / if my memory serves me right /...

hi all,

The above mentines subject amp is completely dead. Found one mosfet short M3. I would like to know if anybody has schematics for this or similar amp. Thank you. Attaching picture.

I know this is niche but I am hoping a few people might have experience with the UDIO-8 with Audiolense. So far I have set the UDIO-8 in ASIO4ALL as playback device and my external sound card/microphone as recording device. And then chosen ASIO4ALL in Audiolense as both playback device and recording device. And no sound in check speaker connections. I have also enabled output channel override.

I have the PC>UDIO-8>two separate DAC's one for high frequency and the other for low> into two separate amps > woofer and compression driver

All to no avail, just can't seem to get any pink noise for the speaker check connections. Any ideas?

I can't imagine it being different from a multichannel DAC.

Hello, sorry if my english is bad. I have build a boombox with a minidsp 2x4 and 4 Tpa3116 is really loud but im triying to upgrade this with a ADAU1701 because i want to use Superbass algorythm and a compressor for bass when the volume is high but i dont know how to implement it in sigmastudio, i'll use the minidsp for crossover and parametric EQ so the ADAU will be between the bluetooth module and the minidsp.

Can you help me with the schematics?
Thank you.


This is one video of my boombox but with the old midwoofers from car audio, now he has 3 Lavoce wsn102-00-8-ohm 10-inch Prueba de sonido altavoz Proyecto Integrado - YouTube
I hope you like it.

For sale are two working Power Follower 2014 amplifier PCBs.
Requires 30v to 42v DC, rectifier bridges and small reservoir capacitor.
Installed are Nichicon, Mundorf and Elna Slimic II caps. By-pass caps not included. Reservoir cap PCB included. Will include 18v protection diodes currently not installed.

Selling because I have 3 other power followers amplifiers and need the case for a large amp build. It is a very good sounding amp, which takes its sound cues from which ever high-gain preamp is in front of it.

More information here: the Power Folllower

Asking $50US, plus paypal and shipping.

Thanks for looking,

Vince

Hi all,

I recently asked me why a tube datasheet contains a maximum rating for the negative grid voltage, e.g. -40V for the 6J6. What may happen when I would hurt that limit?

Thanks for any advice.

all the best, Adrian

Can anyone suggest a credible service agent in London/South East that can look at an Acram C30 pre amp that has lost its output. Arcam are telling me to take it to a dealer and they will charge a flat rate of £300 irrespective of time and cost of parts and there is 2 month turnaround. Want someone that takes pride in their work rather than lashes something up.

Hello,
This is Sreenath, And been a member here for a long time. Hope you all are fine.
Actually I am facing a problem where I bought this TPA3116 Bluetooth Amp with CSR8635 on it, & after I had it installed for my speakers i thought why not I adjust the EQ/DSP to sound perfect.

But, now for some reason I tried to run the PS Tool & Rom Configurator for it and it worked without a problem. But for Some reason the Parameter Manager is not Working.

I tried the CSR8635 ROM Series A03 UFE(CVC) on Win 10 & 7 32bit and it showed this error - The algorithm connected to USB SPI (1003432) identifies itself as E00C @ 44100 Hz, for which there is no available support.

If anyone reads this post please help me get a appropriate Parameter Manager to Control the DSP of CSR8635.

Hey Folks,
I am going to be building a set of frugal horns for these drivers. I have been in touch with Dave D. and he has a set of plans for them. I'll be getting them soon. I will keep this thread updated as I go along with pics and questions.

For now I do have a few questions. My limited reading has me suspecting these will be some really good horns with the exception very high and very low roll off. The low I think I can deal with using a good sub and filters. However, I am not sure of the highs. First, does anyone have a guess asto what frequency I should look at for roll off? 8K, 10K, 12K, ???? Next what spl would be a good level to mate to the horn, 95db/spl/watt? Lastly, Dave reccomended a horn tweeter as best suited to match the horn. Any reccomendations?

My drivers are rated at 5w RMS or 10 peak, so power is not an issue. I will likely run these with an el84 pp tube amp - capable of 5-7 watts RMS clean power.

Thoughts anyone?
mark

Hello all,

Building some ladder attenuators (24 step) for the value amp, have the resistor values (Rx and Ry) for the 100K log LADDER attenuator, but struggling to find the Rx and Ry values for a 1M linear (to use on the tone controls)

Any cheat sheets out there?

Malcolm

Just to share : 16cmユニットのダクト付共鳴管箱~１ - YouTube

Hello All...

I'm planning on ordering 0.1% 1/4 watt 50 PPM PRP 9372 resistors for the TPA Ivy III. Normally this tolerance is not stocked by anyone and the price prohibits ordering one or two sets. Each set will include the following resistors with a cost of $45 plus shipping with a 4 week lead time. I need only 5 people to do it. If more join the price should drop if we get 16 or more. Just reply to this thread if your interested.

750R Qty 4 .25W 0.1% Precision Metal Film
390R Qty 8 .25W 0.1% Precision Metal Film
180R Qty 4 .25W 0.1% Precision Metal Film
2K2 Qty 12 .25W 0.1% Precision Metal Film

Thanks

looking for a set of de5000 with TL-21 and TL-22 accessories.

thanks

Hi everyone

I'm Murasame Yui

My full time job is high power LEV/EV battery PCB designer
Also DIY is my hobby.
So i design a battery wireless amplifier myself.

All the circuit and mechanical and PCB are design by me.

I only build one and will never mass production.
because it's too expensive.

It's spent me over 10,000 USD and 3 month.
(sorry for typing mistake, It's 10,000 USD not 100,000)

USB to Headphone
USB=>Adum3160=>CM6631A=>74HC32=>
AK4399=>MUSES72320=>AD815=>Headphone

BT 5.0 to Headphone
CSR8675=>CS8414=>74HC32=>
AK4399=>MUSES72320=>AD815=>Headphone

Battery capacity Li-po 4000mAh 4S6P = 355Wh

Amplifier


Isolated power supply


Battery & Charger



Finish PCB Transparent view


Use TexasComponent ASM2575 resistor


Old stock military wet Tantalum capacitor


VICOR isolated DC/DC converter


Furutech RCA socket


Building 3D model




Use 3D model to calculating total weight


Use VICOR DC/DC module constant power to heat wet tantalum capacitor


Start building battery


130W High power discharge test


Battery pack building
Also modify the analog voltage meter display range from 0~20V to 12~17V
The 4S Li-po battery empty at 12V and fully charge at 16.8V







Building VICOR Isolated power supply module




Building display panel


Look the-same with 3D model


USB link success


BT5.0 link success


Building AK4399 DAC / MUSES72320 digital volume control and Amplifier board by hand soldering





Add shielding case for DAC/Digital volume/amplifier chip


Final test



Lighting in the dark



Connecting with SONY BT LP player


And this is not the end.
I'm building the Aluminum case now.
I will finish this amplifier end of August.

Hope everybody enjoy my DIY process.

Thank you for watching.

In another post this amp was discussed. I've decided to start a new thread just for this amp because its so unique.

A Schmatic is Available. Its not a great schmatic but its complete.

This is not a amp to start learning audio amplification with...

With 14 TB34's per channel in the last stage, it would double as a arc welder.

Below is the spec sheet in complete pdf format.

Hello,

First post 🙂 I have had a good search but nothing is jumping out that has “live parts” I have a creek audio 4140 that’s only playing mono on the phono input. I think the CD player that was used with it shorted and blew the pre amp. It’s currently using a NE542N

I think I can get an old replacement, I just wondered if anyone has any recommendations / previous.

Cheers

Time to start the design of the next SLAPS application.

This time I want some more power to drive the bass speakers in my four-way setup.

The speakers are Acoustic Elegance TD15H, so they are relative high efficient at 94 dB/ 1 W.

Desired frequency range is roughly 20 Hz to 1000 Hz and desired output power is roughly 40 W.

I got this first suggestion from Circlomanen:



Distortion according to the LTSpice simulation is -68 dB for second harmonic and -80 dB for third at 60 Vpp over 8 ohm, that is 56 W.

First I need to wind a bifilar coil...

I’ve been following the extremely positive response to the D&D 8c with great interest.

One of the more intersting features, IMHO, is the rear firing woofers. I believe these are intended to couple with the rear wall.

This seems to be a similar theory to the Lyngdorf boundary woofers, and others here such as Wayne from Pi audio... ie let the bass be handled by stereo woofers butted up against the front wall and eqed for response and delay.

I’ve been doing this for a while with my current speakers with good results, and I’m wondering how it can be improved.

I have been trying to find an amp that fits some speakers that I have lying around but the more I read about it online, the more confused I am.

I had a Denon Envaya mini speaker that broke a while ago. I opened it up and took out the speakers. I have no idea what the detailed specs of the drivers are, other than that it says 4W and 4ohms on the back.

I have been looking into getting an amplifier board that could power the speakers without destroying it but I have no idea what to choose. I looked on the PCB of the original speaker and there's a TPA3118 chip, but when I look it up online, all the boards with the TPA3118 outputs 2 x 30W. Is that not too much power?

What amplifier boards should I be choosing?

It's my first time trying to build a speaker so any into is really appreciated! 🙂

Forgive me for asking pedestrian questions. I am new at this. I am reading a lot online and my head is starting to spin. Most of the articles I am finding refer to much lower voltage power supplies that I have here (like 12v arduino things, etc.). I have a powersupply that is giving me roughly 410v with the current transformer and for this project I need to get roughly 265 and 285. Is it a fool's errand to try to split this into two rails either with this or a lower value transformer or should I scrap it and start over. Is there a link or article someone could recommend that addresses putting together the voltage divider circuit in an accessible way and how to determine which resisters and diodes to use?

Hi all

I’m looking for suggestions for spectrum analyzer that has the following
- high Z input ( but i guess i can get active probe)
- only need up to 11 or 12 Mhz
- tracking generator in box or support for external one is a must.
- 1 measured channel , 2 channels nice to have but not required
- vintage unit to keep my budget low unless modern USB units can do this
- Must measure THD, markers and 3db points
- would need to store one scan and compare with a second like A/B Or display both simultaneously for visual matching and measuring
- export via gpib to print or save or maybe some software out there (usb if modern unit)
- support to display on a larger external screen would be nice like vga out for example or other means

This is for hobby work not a business so can’t cost too much <500 hopefully that’s possible.

Myself i only know hp 3585a that meets the need and still over my budget so looking for others.

Thanks
Paba

Hi,
I was looking for a way to extract lpcm from HDMI. I've found some chips for this purpose (for example: ADV7623), but i do not like this approach. (too scratch for me)

Can you point me to some boards using that chip?

This is my 6J6-based LTP. For the time being, try to overlook the tail, cathode, and plate resistors - I'm still working out bias and balance after scrapping the CCS.

My question is about NFB, which is coming in via the 8k2 and getting divided by the 100R. That's only pushing 1.2% of the OT signal into the lower grid. For comparison, Fender AB763 uses 820R and 47R for about 5.5%.

The question is, if I want to increase the NFB, should I reduce the 8k2, or increase the 100R? The former would put more NFB onto the tail resistor, while the latter would push up grid and cathode voltages (albeit only slightly). Or should I drop them both down ala Fender? Is there a best practice here?

if someone has a pair to sell , not need to be matched.

thanks 🙂

after some listening and comparing bass reflex speakers (the one with the hole) and fully closed i must say that the bass at bass reflex is really rubbish.

the bass goes at 1 and only frequency loud and you do not hear any other bass frequencies because they are not audible. it is really boring to listen to.

what is your experience? do you like bass reflex? or is it a common knowledge that it sucks?

________________________________________________________________________________________________________

Moderators Note: The title of this thread was changed around the time of post #36, from "bass reflex sucks", as it didn't convey the topic well enough according to e3k.

Hi, would like to ask what kind of transistor I can use to replace the Toshiba 2SK170BL? I can't find any 2SK170BL over place and thinking to change to other parts that can be replaced the Toshiba 2SK170BL.

Hello, how you can explain the R-C-R configuration? Which can be the electro-technical-acoustic difference of having 10.2 ohm instead, or a R-R-C to ground, or C-R-R to ground.

To me R-C-R, R-R-C, C-R-R, C-2R, 2R-C are all electrically equivalent.



Speaker Cable Faceoff 2 - Zobel Networks | Audioholics

Hi all,

So a while back I picked up two speakers second hand, from what I can work out they're custom built and probably minimum 10 years old. Recently had a party and a drunk friend turned on the mic mid-set, massive feedback loop and tweeter on one speaker completely gone.

Have opened it up and was hoping the tweeter would have a model No. or something but the entire loudspeaker seems to be unbranded. Am wondering what the best way for me to determine a replacement would be? I'm like 90% sure that each loudspeaker is 8ohm impedance and 300W but thats all the information I have.

I've attached pictures of the broken tweeter and the wiring on the crossover, also something that has caused confusion to the few people I've shown it to. So far have not managed to work out what the use of the jack inputs is, as have just been hooking it up to amp using speaker wire.

Also while here, as there was a huge surge due to mic and damage to speakers, is there a chance that the amp could be damaged too? and if so is there any way to check? from what I could work out through testing it sounds pretty ok.

My Denon AVR-E300 does not have pre-outs. I'd like to add pre-outs so I can use the receiver as a line source for my active speakers.

Is there a way to bypass the amplifiers to create pre-outs?

The digital board with the DACs has a plug that might be a candidate. Also, the amplifier board has white plugs next to the pots. Are those pre-amp line sources Denon built in but didn't connect because they saved them for their higher end receivers?

As an amplifier this receiver is useless to me. If I could remove the entire amplifier and just run the receiver as pre-out/pre-amp only I'd be a happy clam.

I installed a new voltage doubler to power the signal tube heaters, that used schottky diodes. A few days later, the primary melted down. Nothing connected to the secondaries was damaged. Post mortem, testing with an external supply, currents still seem in spec (600ma for all 5 tubes)

Simulating, I noticed spikes as high as 6 amps in the heater secondary, though using generic silicon diodes instead showed similar spikes. Could that have fried the transformer, or was it a coincidence?

I have a Bose - amp 3510 C5 - AUDI A6 OEM Bose Amplifier 265 030a 3510 C5 (found as "Bose R12" on some sites) I think the pinouts for 25-pin plug are the attached but I don't know what's connected to 4-pin plug.

Any diagram / service book / pinout details ?...

From Europe only please, 2 inputs, and do not need it balanced. Thanxs

Simple test to check speaker and its direct frequency spectrum via amp return with my cinema THX crossover monitor.

I matched the levels so they appear the same the mic distance I can alter it, move it closer inwards or move it further back place another mic near to bass reflex port along with mic directly on axis with JBL 4647, centre channel LF JBL 2226.

I can see the amp return direct showing the LF range I can alter the Behringer DCX2496 crossover and watch the freq spectrum changing.

I had a lead patched into the computer with few alligator-clips to the 3.5mm jack. One output to input was the microphone the other output to input was the THX monitor amplifier return, good as if I connected that directly to the amp it blow the computer up.

I opened two windows of TrueRTA as I was using an audio mixer preamp for the Behringer ECM8000. One window TruaRTA for left channel Amp return and second window for TrueRTA right channel microphone.

I can measure the speaker vs its power input.

Hello,

i found this Gough´s speaker enclosure and i love the concept of refletion of the sound.

but im wondering if it will sound good and if its worth to build one

its a transmission line?

because has a paralell tube but it has no stuffing


somebody heard one of this cabinets?


here is a website dedicated to this cabinet:
History - GOUGH SPEAKERS ARCHIVE


and here two videos video of one :

All hail Jabez Gough and the 1957 vacuum-tube hi-fi - YouTube

Old-school hi-fi with a Gough speaker - YouTube

Hi all,


apologies if this topic has been discussed before but a quick search in the forum did not bring anything relevant.


A few days ago I acquired a beautiful and fully working Pioneer TX 9500 tuner. It has all original electrolytic caps, therefore I am planning to recap the power supply and audio frequency boards. Not too sure about the MPX and IF boards yet as I don't have the equipment for an alignment.


I have noticed that the audio board has tantalum capacitors in the signal path. Initially I thought about replacing them with Nichicon FG series. Unfortunately due to their values, film capacitors would not physically fit.


Given that tantalums are low leakage capacitors, it might be reasonable to replace them with low leakage Nichicon KL series, or just leave them alone. I know that in all vintage Pioneer amps they used to have tantalums everywhere in the signal path and usually they get replaced with electrolytics, but I am debating with myself on this. I am assuming that the Pioneer engineers used them there for a reason (stability, low leakage etc).



Please let me know your experiences all vintage restoration gurus out there.

I requste help of masters,
I want know about PAM8403, can i use module in bridge mode. I have no good knowlage of class D.

Saw this on the eBayz. Hadn’t heard of a B1 with Jensen transformers. Board copyright is 2017. Looks like it would be straightforward to make. Any other info out there?

First Watt B1 Transfomer Buffer Preamp / firstwatt / Pass lab | eBay

Its been a while now since I first laid out a PCB for Mauro's "My Reference" revision C. The first layout was largely a product of taking Mauro's suggestions for a monobloc version and running various iterations past the forum to get as much input as possible.

Well since then literally hundreds of people (maybe more I do not know) have built or are building MyRef. This has given me even more feedback about the layout and spawned some new ideas. Also Mauro has given some guidence on how to make the circuit, and the layout a little better. I have taken this new experience and applied it to a new layout. Here it is for your pleasure.

Major changes:

1) More flexible input and led interfaces allow for terminal blocks, pinheaders, IDC connectors, etc..
2) Bigger more flexible cap space to allow for MKP cap on input.
3) Allowance on power supply for monoluthic rectifier (as in the original) or TO220 types such as MUR860.
4) Additonal output solder holes for direct soldering of large gage wire to the PCB for OUT and OUT-GND.

You can still build the circuit exactly as before, or take advantage of the new features, its your choice. You can also still build the circuit as "Rev A" without much fuss.

Also, the layout has been changed to eliminate as much as possible any sharp angles in the traces. This may not do anything, but I like it better. 🙂 Also many traces are widened, and some little things like silkscreen changes have also been made.

Only circuit features which adhere to the circuit designer's philosophy and intent have been included in the layout, and nothing else ever will be included by me as the circuit is in my opinion, simply put, often imitated, never surpassed. 🙂

Thanks to Mauro for a design which will forever change the way we look at chip amps.

Note: This is the 2 side version which Brian and I have produced, but I am working on a single side version which I will make PDFs for and share freely so those who would like to etch it for yourselves can.

Here it is:

Cheers!
Russ

I've tried this driver in small sealed and ported enclosure and not gotten great results.
Would like to try a quarter wave design but with 90 degree angles as I am rubbish with woodwork. Think Homer's spice rack.
Qts is .45 and vas is 1.25 cubic feet. Would this work in this type of enclosure? Don't want it to be too big but could do tall and narrow. Depth im not too worried about either.
One other thing. I have two of these so would a dual sub be better?
Its primarily for music. I don't do any more than 2.5 channels. It will partner with full range drivers and 10 inch woofers as mains. I have about 400wpc stereo sub amp to.power it/them.
Any guidance would be much appreciated!
Cheers
Peter

Hello, all. Complete noob here so please bear with me if I'm asking rudimentary questions or if I'm posting this thread in the wrong forum altogether.

I recently acquired an old Panasonic PL 530 turntable. I'd like to hook it up to my current system which includes a JVC RX-D206 receiver and a couple of vintage Kenmore speakers (circa 1970). Here are my challenges in getting this set up working:

1.) Due to the configuration of our living room and speaker/AVR setup, the record player needs to live about 10 feet away. The 2 foot RCA cable coming out of the turntable will need a 10 foot extension cable. This alone I think possible maybe calls for a preamp to boost the signal but I don't really know.

2.) I tested the turntable out on the receiver to make sure it'd definitely putting out a clear phono signal--it is. Although there are a few different available RCA inputs on the receiver, the only input that worked was the RCA input labeled "TV". The volume level output sounded a bit low, TV input is already dedicated for use by the television. Not sure whether or not I need to get a new receiver with a "Phono" RCA input, but if at all possible I'd like to avoid having to buy a new receiver.

Thoughts? Advice? Thanks!

Removed this horn from a field house installation we did so I thought I would play around with it. It had a Dukane 1" driver to a 1.4" throat adaptor to a 2" exit throat on the horn. So I threw a 18Sound ND2060A I had laying around and put it on top of a couple of our custom boxes with 18 Sound 15ND9400s, I disconnected the BMS 4594ND mid/highs that are in the box. Biamped it with a xover @ 800Hz/24dB and the thing sounded really impressive. If you walk around out of the pattern it just went away really nicely. The horn feels like a plastic material, not sure if Dukane made these or somebody made them for them.

I don't think my wife will let me set this up on either side of the TV for the Pats game this weekend though.

I have a pair of v1.6 ACA's that I built up from stock kits w/the Meanwell 24V power supplies, biased properly, and listened to for ~20 hours. Asking $400 each plus shipping in CONUS.

Good morning gentlemen,i wonder if some of you could assist with this project..i know these DC300a's have been covered before,but i cant find anything relating to my problem in those threads...i have a DC300a here, circa 1973/74,With an issue...no sound! i have recapped the main board, checked every transistor and diode,checked every resistor (and replaced some out-of value ones where required)...have fitted a new 739 ic,but still the same problem.

Powers up, have 0.00v and 0.01v DC on outputs,so all ok there. I have the correct voltages at the diode pump (90v) But no audio.

I have sent the voltages i am getting on the main board,clearly Q120,Q102,Q220 and Q103 are incorrect.

On the chip,i should be getting 1.35v at pin 1,but i have -2.8v,so something is clearly amiss with this board. I have checked the pcb tracks carefully,there are no breaks or cracks. but now i'm stuck....would appreciate any advise on where to look now.

eBay for $200. Needed woofer surrounds. Refreshed the tweeter’s ferrofluid. And my God was Peter Snell a genius or what? I’m a Snell fan (Type 1’s, K’s, Elll’s, J’s) and he NEVER disappoints! These C’s are awesome. I bought them to give to my sister. And after listening to them, well, I’m happy there are just down the road. And I am still in love with my Snell Type 1’s.

After my last experience with relatively high power SET amplifier (see https://www.diyaudio.com/forums/tubes-valves/327637-lian-845-set-kit-commercial-product.html ), I started thinking about upping the game and getting into power range comparable with push-pull tube amplifiers. There are two ways get there — either use high power tube like 833 or using tube in A2 class where grid gets positive in relation with cathode.

Tubes like 833 require even higher voltages than 845 or 211 and very high output impedance requires extraordinary effort to make output transformer compatible with it and still have enough bandwidth for full range audio. That will result in very expensive design, with a lot of full custom components. Example of that approach is WAVAC 833. But for the $350K price results ( Wavac SH-833 monoblock power amplifier Measurements | Stereophile.com ) are not very impressive.

A2 class though can allow lower plate voltages with higher current, thus reducing requirements to power supply and transformer design. Load impedance 4-6K ohms is very much achievable without extraordinary effort. With output tube operating with grid current you need to have low impedance driver circuit. Easiest way to achieve that is using cathode follower with direct connection to grid of output tube. It is possible to use 845 or 211 tube that way, but there are also other tubes which were design to have grid current almost at all signal levels. One of examples is 805/838 tube. The only real difference between them is that original 805 had a plate cup, and 838 did not. Today China makes 838 equivalent, which for some reason they call 805. Thus when you buy a new production 805 tube, you are getting 838. Of cause neither of these tubes is really affordable as NOS — they almost all gone and were not manufactured outside of China for decades.

I didn’t want to do build from scratch and just like with 845 based amplifier I referenced above, I decided to get a modern Chinese amplifier and start from there. Line Magnetics is a mid-range Chinese brand which builds and markets tube amplifiers all over the world. They have amplifier based on 805 tube which is claimed to reach 48W of output power. Price (if you buy direct from China) is in relatively affordable range, even when one account for international shipping charges. And finally I made a move and placed on line order.

After 3 weeks of waiting UPS guy knock on my door, and when I opened it, large cartoon box was sitting next to it. The box has some signs of tear, which is explainable (it“s path was from mainland China to Honk Kong, to Japan, to Chicago and finally to Dallas). But when I opened it — everything inside was in pristine shape. Tripple boxing and attention to packing details did the job.

One note — when you buy direct from China, you likely getting the version that requires 220 volts power line. Some devices can be modified to use 120V, some are not. From what I read about Line Magnetics gear, I thought that I will be able to easily convert it with s bit of soldering around power transformer. But I also had a boost transformer, which I purchased many years ago, but never put in service. Thus I was ready to use amplifier out of the box too. As alternative, you can arrange 240V outlet in you music room — many audiophiles have it already. If you do not, getting step up transformer is much cheaper than hiring electrician. In the end I found that my version of amplifier (made some time in late 2019) does not allows easy voltage change, and I kept it running with boost transformer. But to use in my high-endish music room I bout another transformer, which simply looks more in place (UMI Step UP 110 to 220 Voltage Converter found on Amazon). It is rated for 1200VA which is well enough for amplifier that consumes 500W.

Line Magnetic LM-508ia has excellent fit and finish. Designers had clear attention to details and manufacturing quality was excellent. All chassis is covered with mirror like enamel probably ½ mm thick. Connectors for inputs and speaker outputs are of high quality. Amplifier came with pair of Line Magnetic branded Chinese 805 tubes, pair of also LM branded 300B tubes (used as drivers), pair of new production Electro-Harmonic 6SN7made in Russia, and a Chinese 6N9P (equivalent of 6SL7) tube of unknown brand. Later we will see that this amplifier works best with tubes that came with it from the factory.

LM-508ia has two adjustments — output tube current and hum balancing. When I turned it on, both of these adjustments were spot on. It only can be explained if each unit is tested and adjusted right before it is packed into the box.

This amplifier has simple classic circuit (see Pic.1) : there are two stages of amplification which are classic resistor amplifiers with half of 6SL7 and paralleled 6SN7, loaded with 300B as cathode follower directly connected to grid of 805 tube. The latter has relatively low plate voltage, and grid is positive at idle. 300B operates with negative cathode source and idle current at about 40mA, while output tube is biased to 120mA of plate current. All that results in constant power consumption of about 500W. Power consumption does not change while you play music — this amplifier really operates in A class. Al power sources use solid state rectification and CLC filtering. Circuit includes timer that delays high voltage until all tubes are warmed up. Additional digital circuit is used for remotely controlled volume pot. I used this unit as pure power amplifier and thus remote control was put back in the box until I decide to sell it.

LM-508ia has three regular inputs, which can be selected with front switch and affected by volume control, and fourth input that bypasses volume pot and designed for use with per-amplifier. Unfortunately the circuit does not change and all gain stages are used in either case. Thus the only advantage of using fourth input — it ignores volume control setting. But noise/him level stays the same regardless of which input you use. Like almost all tube amplifier, this unit has some hiss and noise at the output which can be heard through speakers when you are close to them (my reference solid state Bryston is dead quiet in comparison), but I didn’t hear any hum from my sitting position 8 feet away. I measured AC noise at speaker and it was below 2mV. Main type of noise is random hiss and some hum like sound from 60Hz power line frequency and its harmonics. Pic.2 shows spectrum of noise as it was measured by me.

Before putting amplifier on my workbench, I decided to play few records with it. The result was generally positive. It plays loud enough through my 89db/W speakers without obvious signs of clipping. Overall sound was something between my 845 based amplifier (it was not as soft) and solid state Bryston (LM still played like tube amplifier). There is one more setting switch available — it adjust amount of global negative feedback to listener“s liking. Unlike A1 class amplifiers, this amplifier needs some amount of negative feedback to reduce distortion and output impedance to make it compatible with modern speakers using complex crossovers. I initially use 8 ohm output and least amount of feedback (almost none), but bass was uncontrollable. Increasing feedback to second position improved sound significantly. I also tried to use 4 ohm outputs and like it more. In the end the best for my speakers was 4 ohm output and second setting of feedback. When I tried to increase feedback, bass became even tighter, but overall sound stage started collapse. It is clear why variable feedback feature was included — make amplifier work best with various speakers.

>>>see follow up below<<<

I recently received a free Sony SRT-V3 with some sentimental value. The unit did not power up. Opening it up I noticed the primary 4a fuse was blown. The fuse appeared to be a fast blow fuse. I replaced it with a slow blow and now the unit will power up. Now when turned on, the two emitter resistors (R725 and R726) glow bright. R725 is cracked and starts to smoke. The other two emitter resistors (R774 and R775) both test .01 on 20kOhms.

I'm trying to test components and remember classes from 25 years ago so please forgive my limit understands.

I tested the output transistors on my diode setting and Q713 is shorted, Q714 tests 066 both ways, Q764 tests 459 (black on base) 687 (red on base), Q763 tests 504 (red on base) 637 (black on base).

I'm wondering if I can get feed back on how I see things?

Seems obvious that the R725 and R726 need to be replaced. I believe R774 and R775 need to be replaced as well. Q713 needs to be replaced. I believe the other three output transistors need to be replaced. From what I understand PNP and NPN should not give readings both ways and voltage should read between .45V to .9V.

Am I correct in how I'm understanding my testing?

Lastly, where is a good site to go to to find replacement compontents? I've discovered el-component for replacement part numbers for the output transistors but I can't find anything to help find replacement MPC resistors.

Thanks in advance for any advice, feedback, and gentle insults.

I have a Cyrus 3 that sounds great, but every time I turn it on, it makes an almighty thump. I think it is supposed to be a 'soft switch on'. Can anyone suggest what might need servicing?

I thought I might replace the power caps, but beyond that I don't know what it will need. anyone know how to check the bias and adjust DC offset on this?

Thanks!

With the advent of DSP's and using them for crossovers, why at the crossover point can't we just cut the signal? I understand the reason in the analog world but other than "thats the way we used to do it" I don't see why you can't just hand off from one speaker to the next?

title says it all
enjoy
DIY Speakers and Acoustic Panels - YouTube

Hi Guys,

Is anyone using these ? Would appreciate if you would share your thoughts on sound & reliability in comparison to other brands.

Thanks

The AirBlade Transducer | audioXpress
Looks very interesting.
Vince

Does anyone have the service manual or schematic for the Audio Precision System 2? I can find the System 1 all over the internet, but nothing on the System 2. I've seen a picture of it in a binder, but nothing downloadable including the AP website.

I am thinking of buliding stereo (later active) 2 way system for my friend, using Sympatico amplifier modules. It will be feed through balanced connections with DAC/preamp or miniDSP. Since I have not get yet any listening experiences using LM4780 in such configuration, I am asking Sympatico builders about their opinions about this project, which loudspeakers are you using and how far should I put sound performance expectation?


Thanks in advance.

Hello everyone,

I've been working on some simple single ended guitar amp designs over the past few months and I really want to try running a 6V6 and an EL84 in parallel for the power amp section! I've drawn a rough schematic and attached it to the post, so can someone take a look real quick and let me know if I'm on the right track and if this can be done?! I know I'll need an ideal primary impedance of 3000 ohms on the OT, but the hammond 125ese can be had with a 2500 or 5000 primary so that should be close enough right? As I said before the schematic is purely conceptual, I haven't breadboarded anything yet, I just want some people's opinions on whether this can be done with no issues and also if there are any recommended changes to my design.

Thanks for your help and comments in advance!

Remember how the people who invented the atomic bomb came out later saying that they regretted it. I was reminded of that after watching the creators of social media interviewed in "The Social Dilemma" now available on Netflix. I found it terrifying. It is not perfect or anything, but watching the people who built the machine describe how it works and what it is really doing is a must see. I have worked in software for many years, I had only a vague idea of what was going on. It is too long, and too polished, but that may appeal to the widest audience. If you have ever spent time developing an algorithm that optimized something, you understand how badly single parameter blind optimization can go wrong. Imagine how long it would take an optimization algorithm with the only goal of maximizing the acceleration of a car to figure out that running into a solid wall gives the peak acceleration. Look around at your family and friends and see if you can pry them away from social media for a day. Go ahead and try. Turn off the internet at your house, you will find yourself alone in a few hours as the others go find internet elsewhere. Remind you of a gambling addiction?

Just wandering if anyone has a different crossover for exactly same drivers arrangement dual 18w8531 and 6600 aircirc tweeter It can be 2way ,2.5 way or even 3 way. Not looking for computer simulations. Thx for reading my post

I have an oldie but a goodie Integrated Power Amp Technics SU Z780. The power On/Off switch (ESB8249V) fails to remain making contact and of course the amp goes off. If I hold the power button in, the unit will stay on. I can't find this switch or any replacement on the market. I am hoping someone has an idea where I might get one.

Moon and Stereo
Best Buy Award

Mono and Stereo High-End Audio Magazine: THE GREATEST BANG FOR THE BUCK - ELEKIT TU-8500 REVIEW

Hi guys, I need your advise, for a project I need +5v gnd -5v, I have a HD Plex 300w power supply and I´d like to use it, but it only give + voltages.

Do you know if there is a way to get a negative voltage from any where inside that psu?

I know I could do it with an oscilator, diodes and capacitors, but could be more elegant just to get it from psu.

Thanks,

Hi

Looking for 1 pcb (unpopulated or used) for a pair of 6B4G I’d like to listen to...

Please send me a PM if you have one you don’t intend to use.

Thanks
Eric

I was constructing a new metal plate for a test. and took another look at the B&G neo 3 PDR.
Why are they so efficient and why do my measurements of them look so bad?

well here is the answer. i dont know how old they are to be honest.

RECTIFICATION! , i say somewhere 1.5 Khz at 1 watt. that should be 2.85 volt. in this case being 4 ohms ~ means 2 watt.
- i say it distorts insanely at 1.5khz.. it is actually 3 Khz..

Common B&G Neo 3/PDR Planar Tweeter failures - YouTube

Recently I rebuild a pair of Audiostatics ESH100. An almost full range electrostatic with integrated bass reflex for the lowest octave.
Listening to the end result I noticed that one of the ESL's had a lower output and that when playing louder distortion is occurring sooner than on the other one.
To stabilize the diaphragm Audiostatics applied silicon dots between the wire stator and the diaphragm. Upon inspection it turned out that on the low output speaker the silicone dots were much bigger than on the other one. And what's more it looks like the dots are sucking the diaphragm closer to one side of the stator. The pictures are showing clearly that the silicon sealant is producing dents in the diaphragm. In my opinion caused by shrinking of the sealant.
I would appreciate to get some help about alternatives, like advice about non shrinking (clear) silicon kit or paste, the use of double sided foam tape or perhaps the use of kneadable rubber/putty.

Howdy Neighbours,


Just fer giggles, let's try this:







..puttin' the DIY BACK into diyaudio...

Hun, so this is a REcreation of " "T's" Inverted GainClone ". It obliviously wasn't his, but rather somebody took his idea of an inverted gainclone power amp and thru a pot on the front ...

...

Doh! [1st Task: why is this 'amp' unstable? ]



So I recall T noting (re his power amp) that using an opamp [no matter signal or power] in invert. config. has some advantages:


A) You can choose the values on the +input so they match the -input's (better balance; tweak by actual measurement)

B) Invert. operation provides that nifty virtual ground that, because of the fet input, physically ACTS almost IDEAL [acting purely mathematical, with no real-world 'fudge' factor] and thus has these tech. advantages ... blah, blah, blah, ... I can't recall what he said.

...oh, oh , and I thought:

C) Well, because [in this particular case] the pot sets the input impedance, Rin and Rf can be dropped by an order of magnitude to provide better noise and more current through the resistors [and junction] that provides further benefit by ... blah, blah, blah, I can't recall what I thought. ;}

D) So I'd like to correct and develop this circuit and build it and do some basic testing and listening and ... and, d o i t m y s e l f , ... if ya know what I mean ...



Cheers from the

ALD

man!

PS And YES that's how yer supposed to spell n e i g h b o U r s!!11!1!

PPS It's not DOUBLE inverted .... Yet!

PPPS This project wasn't getting much traction in the Loungy thread sooooooooooo ..................

I'm new to diy speakers, only starting down this rabbit hole a week or so ago. I want to build a high end portable bluetooth boombox. Something that will wow me and my family that I can bring along when we go on trips or parties.

This is my list so far
Monoprice Premium Bluetooth 5 Transmitter & Receiver- for the bluetooth
minidsp 2x4 hd - using it as crossover
ICEpower 50ASX2SE - for the tweeter and midrange
ICEpower 125ASX2 - for the woofer

Drivers
ScanSpeak 15W/8530K-00 - midrange
ScanSpeak Illuminator D3004/6040-00 or the be version if that is worth the extra 200$
not exactly sure what woofer to get

Currently considering passive radiators or ported but not entirely sure what the advantages and disadvantages are. Also considering just using a predesigned center speaker and modifying it somewhat to make it bluetooth and portable.

Dayton Audio SD215A-88 8"
+
Dayton Audio DSA215-PR 8"

do you think i can just spray paint them ? will need 2-3 coats of paint i guess

Following the suggestions that everybody should have one 😀



Situated in Spain, payment PP gift or SEPA transfer.



Thank you.

Hi and good morning all
ive aquired a pair of B&W DM305 Floorstanders and 1 of the prism back panels vibrates at certain bass frquencies ive taken the driver out and can see that B&W only glued them top and bottom of cabinet to the prism piece and not to sides which seems to be where the vibration occurs ive taken a pic of original glue but not sure what it is or what i could use instead to reseal the sides inside to try and stop vibration. Obviously i need a longish nozzle to be able to get inside cabinet and reach past prisms to reach sides.
Any help would be appreciated

Greetings from Indonesia.

I am interested to build my first diy loudspeaker. And I stumbled on this optimo design. These drivers are commonly available here in Indonesia, so I think I will give it a shot.

Can someone help me with higher resolution pdf on the built sheet, concerning the measurement of the box please..?

Many thx before

I have some MUR3020 diodes I want to use in an upcoming dual mono PSU build, does anyone has ie. the Teabag PSU diode bridge PSU for offer, not the complete PSU, would appreciate that

perhaps there's someone here who remembers them.

https://www.diyaudio.com/forums/ful...-rocket-rise-klam-projectors-post6343074.html

I thought I'd finally say hello 🙂

I'm a complete novice & beginner but also curious - which can be a very annoying combination for experts. Why? 😀

Creating a small headphone capable DAC/Amp is on my list of things todo, which according to the Mrs is long and involves completing the new Koi pond first (13,000 litres or 3434 US gallons) that is taking my spare time, and should be complete sometime next year. However as winter sets in - it limits the dig/concreting that can be done so I start thinking of next thing on the list..

Last december I looked at the soekris DAC and this this year I've been researching Marcel & Naughtiboy's tube DACs as a comparison. I have to say it seems more attractive from an implementation POV plus the tubes should keep me warm in winter!

I have an old pair of Castle Harlechs (v1), Musical Fidelity A220 and a Myryad MC100 CD player that doesn't really get much of a play now days compared to the Mac and headphones. Not high end, but quite class-A with the A220 and Myriad being 'A-biased' AB.

I've been in software for over twenty years, ranging from embedded (Z80 to ARM and Blackfin) through FFT based GPU based image processing and deconvolution using FIR etc to quantum computing and cryptography (the day job).

Music - I tend to be open minded, although I play guitar and drums badly since school. I still have my old Fender Strat '88 and listen to a very wide range, probably a good example of my eclectic collection 🙂
* Opera - Puccinni arias mainly
* Stanton Moore - All Kooked out, that's New Orleans..
* Police, Clapton, prog-rock
* Reggae from Alberosie, Queen Ifrica
* Electro-music - from Garry Neuman through Art of Noise, Orbital etc
* Hard dance - wide range here, but typically more intense.
* James Brown - drumming at it's finest
* Led Zeppelin, Iron Maiden, Nightwish, Devin Townsend
* Meshuggah, Opeth, some Panzerchrist, Symphony X etc.

I suppose anything that drives emotion and intensity perhaps!

For sale verry good sounding D class amp.I put this some time ago in wood enclosure with some AC filter and conectors.The main capacitor are now supern Nichicon KX.Thie little unit souns superb and the sound is worth every penny.I have try this against some verry expensive amps and the little Anaview was superb in all areas.Im using now tube power amps,so dont use this anymore.Just plug and play.price 150 euro plus shipping or best offer.

I'm a complete novice at DIY audio and only picked up a soldering iron for the first time a few weeks ago. I am trying to finish a chip amp and need help. I hope this is the place I'm going to find it! Other places I've tried, have, shall we say, been a little snobby and very unhelpful. I have hope in you lot! 🙂