Hi at all.
IF i have an DHT triode amp with 3K : 8ohms output transformer.

And If i have a compression driver working since 2.5kz with 8ohms curve and also a 5 ohms resistor in series.
The plate load change with a 8 ohms driver , and the additionaly 5 ohms series resistor ?

Or this resistor does not change the load that the plate tube see since 2.5kz ?

The series resistor Influences in some way ?

Santiago

Interested in the various ways there are whereby one can generate a negative voltage within a given tube amp design. The more legit, the better. This is asked in the context of avoiding having to install an additional AC line step down tranny. I'm also assuming "flea power", in the single digit mA or so.

I've tried a voltage doubler off an unused 6.3V heater winding. With a slight load to enable an adjustment pot, it barely gets up the -10V needed for a 6BQ5 P-P design. (Next up to bat is a voltage triple-er)

I've seen an RCA design where a capacitor connects to one side of the B+ tranny winding, followed by a resistor to ground. Then to the cathode of a diode, then cap to ground.

Other ideas?

I just got a dead CX-800 pre amp I hoped to repair. it does not turn on.
there are no fuses anywhere that I can see
120 goes into the transformer but nothing come out
input leads for the transformer shows no resistance at all, as in completely open it seems
lifted up transformer to look underneath, it is epoxy encased

outputs are
red black red for 23 gnd 23V
orange orange 14V

I am wondering why I can find no fuses at all (even on the schematic) and the big question, what can I use in place of this transformer

I recently had my crossovers rebuilt. We changed the tweeter resistor from 2.5 ohm to 3.9 ohm to lower the output. It dropped it about 2 dB per REW test. I would like to hear it again at 2.5, but instead of removing the 3.9 (Path audio) resistor, I was going to add a 6.8 in parallel, which would drop the resistance to 2.5.

But that value is on back order from Parts Conn, could I use a different brand, say Mills MRA 12 6.8?

2 questions, is mixing brands a bad idea, and mixing values?

Thanks

Hi everyone, I need some help regarding replacing one of the transistor on my krell s-300i amp.

The transistor has a marking of 1GW (very small transistor). I googled and it shows up as BC847C. I also notice that several other similar transistors have been replaced (bought the amd 2nd hand). I think they don't really last (read about high failure rate of this amp).

I am thinking if there are any alternatives for this? Something that could last longer.

Thanks for the help!!!

I'm not positive on the identification of the PS components.

All PS fets are damaged. Looks like they are IRF1404 but I'm not totally sure. I would think IRF3205 or similar might work here in this amp? Not totally sure. 51ohm gate resistors are measuring OK but need to be replaced.

TL494 IC with several buffers. A few of them are burned and not recognizable:

Q103: ??
Q104: 2A?
D105: 5D
Q105: 1A
Q106: 1A

Is there a schematic available for this one?

https://www.crutchfield.com/S-oml7d...C_Wa2scYmqp86MxlQXGmHy6Y3RjQlgYhoCqucQAvD_BwE

Hi all,

Hoping I can get some help with this old Cyrus One. The left channel sounds weak and has mild distortion. I’ve been through with a scope with a 1khz sine wave and the Voltages and wave form look great and voltage at the power transistors are identical. I’ve checked and cleaned pots and even applied the signal directly to the power amp circuit, bypassing the controls. Also there was a bias issue on this channel, I’ve reduced a resistor in the bias circuit and got 8mv. Also recapped this circuit. Any ideas guys?

cheers

Such capacitors I have never seen before:
https://www.eeworldonline.com/cde-snap-in-aluminum-electrolytic-caps-handle-600-vdc/
https://www.cde.com/new-product/380lx-and-381lx/
https://eu.mouser.com/ProductDetail/KEMET/ALA7DA331EE600?qs=sGAEpiMZZMvwFf0viD3Y3a3yb5D6sPUg3Mw1Ii53gqabpUqe8jhz/A==

The usual method of connecting electrolytic capacitors in series to increase the value for VDC (when the ESR value doubles) should therefore be a thing of the past. In case of replacements of four caps all can operate in parallel mode up to 550VDC supply voltage.
Are there any experiences ?

I have actually 2 amps from the same person with the exact issue. No audio. Amp Powers up and draws proper idle current and has no shorted mosfets, or output transistors. I have had many prime mono channels amps that an inductors has came from the board. But I have seen this a few times and can not fiqure it out. I need a signal generator. For now in going to push an audio signal into the amp and try and follow the 50htz signal? It's not so easy the way the board is layed out. Just wondering if anyone has found a solution to this issue already? Or some advise

Hi all-

These days it seems I find many NOS tubes have gone gassy from age. Tube testers do not check for this. Is there a jig or circuit or DIY rig that does check for gas? Thanks.

Ive got this amp, a bit un-familiar. The driver board is epoxied. The amp attempts to power up for a brief few seconds but then falls straight into protect. All transistors are measuring OK and everything seems well enough in-order on the pcb. Any thoughts as to why it stays in protect?

Photo

I am looking for step-by-step instructions, with photos, to show how to set the CDM-2/10 laser diode voltage to 50mV for correct focusing of the TOC on a CD. I have the Philips C.D.M.-2 service manual, but it is not specific on which resistor on the control board (CB) must be used. I have seen comments here that it is located in the bottom right corner of the CB. I believe this to be R3131.

I remember searching the web and finding a site where this information was contained, but have since lost that history on my browser. I have read Laserology by Lamizator.eu, and while very informative, it is not specific enough for me. Yes, it shows the pots and what they are used for, but not the resistor location on the underside of the CB.

I have also read CDM2 Revision by Bakura, and while informative, not what I am looking for. The closest I have found is the CDM 4/19 to CDM2/10 laser swap blog on audiokarma.org - and while getting close to what I need, it is still short of what I once saw on the web.

Any pointers or URLs are most welcome.
Thanks

I mainly made this document for my own records but I think the design is a good way of getting decent output from cheap high Qts car subwoofer drivers. The measured maximum output is >115dB/1m @ 30Hz.

Hey guys.

Have started a wedding band who are now looking to purchase its own PA.

We want to go with just tops for convenience and logistics ( don't want the hassle of carrying subs to every gig )

Which speakers would you recommend that can cover the whole band? And are 12 or 15's better.

Details:

7 piece band - drums, bass, guitar, keys and 3 vocalists.

Gigs - standard weddings / corporate 100 - 150 people.

Budget IS important so ideally looking for the cheapest speakers that can get the job done.

Thanks in advance

Apparently it is possible to build a Hi-Fi 'chip amp' for a very low cost. I thought it might be an interesting exercise to design one and build it later at an appropriate time.

The unit will be wall mounted on a rack similar to this one:

Initial 3D model of the case is as shown in the attached graphic.

Plan to use an external power brick and an amplifier chip that is capable of 2 Watts to 5 Watts.

Amplifier board like this one?

I see lots of very sophisticated projects here with people doing smart stuff with Arduino and Pi and all sorts. So I feel suitably chastened in posting this but may be of some interest to someone.

Having finished my first Chipamp I was left with a Cambridge Audio A1 case and some of the internals and decided to repurpose them into a preamp to feed the Chipamp. All very simple stuff. I sourced a modest 30VA 15-0-15 toroid. I stripped out the old regulator system (just Zeners) from both the main preamp board and the input board and installed a proper linear regulator based on L78/7915. I did some rerouting on the input board to cut out the the tape loop and give myself just another line level input. Then obviously I had to rewire everything together and in doing so tried to adhere to some better routing than the original design allowed (given that it had a comparatively massive power amp board in there).

So the design (as per original) is simple. An inverting buffer on input, feeding a shunt feedback Baxandall tone circuit (so again inverting), feeding a pot and then straight to output. So this last stage is a 'passive' preamp. I use short cables and the pot is 20k (ln) so no issues there, but I will be adding a final buffer stage just for versatility to allow longer cables if wanted (may enable both buffered and non-buffered outputs).

On to opamps. So much written I know but I will keep it brief. It came with TL072 in both stages. I am a great fan of TL072 from long back and in these low or unity gain circuits I didn't see a compelling reason to change, but I had socketed the boards and so experimented a little. Tried 4558, NE5532 and AD712 (as used in more upmarket Cambridge Audio A3i). I measured all of them for noise (pretty negligible in all cases but measurable differences) and did some listening tests.

OK my ears are not good and I am not therefore a great guide on sound quality - whatever that means. In all honesty I really couldn't reliably tell them apart. Its quite useful that the tone circuit is switchable so its possible to switch one op amp out of circuit and this did reveal a very slight degradation due to the 4558 - very slight, but female vocals just didn't sound as convincing (at least not to me). For the others I couldn't have reliably told whether the tone circuit was on or off with a blind test. So on this criteria alone the 4558 drops out of contention.

On to noise. Interesting. The differences are tiny and all versions are getting close to the noise floor of my ancient Levell muV meter but here it is. The noisiest (in this circuit) was the TL072, the quietest was the AD712. The total measured difference (full volume, tone on) was only around 10muV from best to worst but given the low levels I was measuring (20-30muV) I guess this is quite a large percentage. However .... it was impossible to tell them apart in practice unless my ear was right up against the speaker. In that case I would say the TL072 noise was a bit more objectionable / noticeable as in being more popcorn like.

Then I am going to add a criteria. DC offset. No surprise here the NE5532 was worst by a country mile. So what? Well the NE5532 implementation would be unusable without some switch on delay relay / switch off mute. I say that because if ever by accident you were to switch off that preamp first (or switch it on last) with NE5532 on board there would be very loud, very unpleasant and possibly damaging loudspeaker cone excursions. I tried it without tone enabled and volume turned down and it was bad enough. The TL072 by comparison was relatively benign (but you would still want to avoid a mistake of powering down preamp with power amp on). The AD712 was just a dreamboat. I couldn't measure any DC offset and it starts up and shuts down almost silently.

Perhaps no surprises - a circuit designed with JFET opamps works better with JFET opamps. But then the performance of the AD712 in comparison with TL072 did take me aback. Received wisdom is this is an ancient 80s opamp and offers no real benefit over the TL072. And I hadn't realised the benefit of DC precision is potentially simplifying a design. It was therefore measurable better and much more practical. In fact for the audiophile approach, DC offset is so low i could easily remove at least two DC blocking capacitors per channel if I wanted to. Picture of new internals just for the hell of it.

I have 3 way DIY speakers. Midrange is Accuton 173-6-090, Scan Speak Revelator tweeter, ring radiator. The crossover is 6 dB per octave. The midrange is 120uF and 0.56 mH. The tweeter is 3.9 uF. Distortions, sibilants are heard in the area of high tones. I tried other speakers in the setup, there were no distortions or sibilants. I read about how the SS ring radiator can’t play low. I have experience with the Vifa ring radiator, which also couldn’t play low without distortion. I would like to keep the crossover 6 dB per octave, because I have expensive elements, and I also like the connection and phase correctness of such a crossover. I wonder if you know which tweeter could play with my Accuton midrange and 6 dB per octave crossover? Best from own experience with similar drivers.

I have a Becker BE1480 tape deck in my car and lately it has eaten two cassettes. I'm thinking that I'd need to replace the pinch rollers in this 32 yo deck which would seem to be long overdue.

When I open the deck I see a tiny plastic disc holding the pinch roller in place. My question is: can I pry/pop off the disc in order to replace the pinch roller or should I not tamper with this piece?

I'm sure others have come across this when selecting a power transformer. For a project I'm working on, I found a power transformer with the perfect voltage and current high voltage winding and a perfect filament current rating. Problem is the filament winding does not have a center tap. I've had the same situation before and a solution I have found that cancels background filament hum is to add bypass caps from each side of the AC filament line to chassis ground. I find ceramic caps work best for bypassing and 50V multilayer ceramic caps are small enough to fit anywhere. I ground the caps to the chassis and not directly to audio ground circuits. The 120V AC power inlet third prong ground also connects to the chassis and not directly to audio grounds. Although audio grounds do connect to the chassis, all audio grounds are wired together. Copper wire is a better conductor than a chassis giving some degree of isolation between audio ground and AC ground. I have never had a hum problem (so far 😊).

Below I Haves shared Measurements of My Driver using DATS V3
FS comes out to be 86.3 and if can be clearly see a dip of graph which the software has analyzed as fs because of impedance peak.
but can be clearly seen it can play below 86.3 hz
so my question is how to calculate fs in such case as modeling software modeled graph will be only upto 86 hz

Hi,

I am looking for a remote control for the Perreaux SM6 preamp or for the codes for the programming of a programmable remote control. Anybody knows where I can find the codes?

I thought I'd re-animate this project because it my promote discussion between the factions. Summer's here. It's barbecue time so I want to create a blue-tooth boom-box. It has dual power sources AC mains and a 12v rechargeable DC battery. Somebody has to carry this so I'll limit the size to 20 litres.

At this point anybody in the car stereo business need to seriously re-think their priorities. The 12v battery needs to last all day. throwing more power at a problem can never be the answer. (Within reason) the priority has to be dB per watt. Having torn down more systems than I can recall I have an inkling how the big box manufacturers have addressed this issue.

My draft design incorporates 6 drivers (2 x 3-way speakers) in a shared 20 litre box. The woofers are 6" and the single port is tuned to 90Hz. The efficiency theory starts at the signal: do not ask the amp to waste power amplifying inefficient signals. If the amp is not amplifying signals below 70Hz (12dB per octave) then it has twice as much power to power the rest.

It's just a holiday Boom-box. It doesn't have to be perfect.

Can anyone help with the conversion of the amp below to Si transistors?

Use will be a general purpose test bench amp.

Many thanks in advance.

HV20821

Asia'x capacitors,Yunxing Aluminum Electrolytic Capacitors,Yunrui capacitors agent.TOP Quality,ISO9001 Certified RoHs & REACH Approved,Cooperated with PHILIPS lighting for many years, no customer complaint.
https://www.super-capacitors.com/

Got a good deal on Stax ESL-F81 electrostatic speakers. They are in good working condition.

I am trying to figure out what amps would drive F81 best. I have a Class A 20W custom made ECC88/MOSFET Amp: works great with high sensitivity speakers but fails badly with Stax, McCormack DNA-1 Deluxe: drives Stax fine but is not as fluid as Aleph 3, Pass Aleph 3: works fine but clips at higher SPL and Symphonic Line RG11 that works nicely but does not bring anything special to the table. As you can see these are very demanding speakers.





With impedance all over the place from 2Ω to 500Ω depending on the frequency what would be an ideal amp? Please provide commercial models as well as DIY choices and general ideas.

Hi

I'd like to present a diy-instructions for versatile acoustic folding screen called Acoustic Blockchain.
Originally this blockchain was developed to be used in Finnish Hifi events by a Finnish hifi association Hifiharrastajat ry which usually means hotel rooms with minimal acoustic treatment.
It had to be light weight, no breaking parts, acoustic material is safe i.e. nothing to breath into your lungs, no injuries if it falls over, easy to transport,
easy to relocate in room where most effective, usable as a bass trap and effective against room echo/reflections and above all simple to make.
As a bonus it is 100% recyclable.

The Acoustic Blockchain is versatile and easily portable acoustic folding screen made from upholstered acoustic panels.

It has many possible uses:

• open offices/studios
• home acoustics (children's rooms, home office, hifi listening spaces etc.)
• music rehearsal spaces
• etc.

It can be used as permanent or temporary solution as it can easily be folded away (and even put under the bed) when not
needed releasing usable room space for other activities.

This gives you an option to have acoustic treatment in front of windows, doors etc. during critical listening. Also it is easy to find the most effective place for acoustic treatment as you can easily relocate it during listening/making room acoustic measurements.

Direct link to the guide at issuu.com: Acoustic Blockchain
The attached Acoustic_Blockchain_improvements.pdf contains few ideas on how to possibly improve the original design.

Material used is polyester wool with density of 22kg/m3.

Hi guys.
I'm looking for an equivalent or replacement part for this IC: TL783C or LM783C.
I have an AMEK-TAC series 350 power supply and this part is mounted in the 48V phantom section. I fact, it is the only IC or transistor present in this 48V circuit. Here is the circuit diagram.
Can anyone help me?
Thanks in advance.

Hi,

I can get this subwoofer locally at a very good price (don't recommend any other model as in my country we don't have many available) thus I would like to know how well can the 18sound 18LW1400 perform for subwoofer duty, considering this:

-. I have a very small room, maybe 8 or 9 square meters.
-. Use will be for HT
-. Listening levels will be between 85db and 90db (maybe even less)
-. Have DSP capability
-. The idea is to build 4x subwoofers like this

So, taking advantage of the huge area of this SW, the great sensitivity and power handling and kind of poor XMAX, I though:

-. Use 2 drivers per box, connected in parallel (4ohm)
-. sealed box around 50 liters (for the 2 drivers)
-. 500w amp
-. Apply some Linkwitz Transform + HP around 10hz + (-)12db gain across al the spectrum (I don't need 120db@100hz)

With all that, I do have some good performance according to WinISD. I do hit XMAX at around 200W but I am already above 100db@20hz! Also, I would assume that 8x 18" will pressurize my room at a whole other level.

I understand that according to WinISD I will need a TON of power (above 2kW) but if I consider the huge room gain I might get in my room then I can use a higher fp in the LT and reduce the power needed to get similar performance, or maybe get a bigger sealed box of around 80-90 liters.

So, are these assumptions correct? I uploaded some pictures comparing this simulated driver (in red) vs a dual SBAcoustics 10" SW26DBAC76-3-DV in a small sealed box (in blue)

Cheers

Looking for a stereo input multieffects pedals, know any? Also, most effects pedals (Roland, Boss, Zoom) Multi-effects pedals have aux in, is this also channel R?

Want to plug my tascam mixer stereo sub into effects pedal with auto-pan into SPL Stereo Tube vitalizer then to main, lol!

I am wandering here from the Chip Amp pages having just completed an Lm3886 project. I am now keen to explore the world of Class D. So far my only experience is Fiio A1 desktop speaker amp. Pulled it out of the case and it seems to be based on TFA9815T with an OPA2134 op amp front end (nice touch!). This little critter sounds pretty good but I am keen to build a Class D amp for myself. I dont want to populate the boards so really am looking for advice on what sort of completed boards to source with a view to putting it all together. Maybe with a linear power supply (as I feel comfortable making one of those)?. Thanks

I have a pair of SB26STCN tweeters looking for a mid-bass and crossover. I'm assuming the SB26STCN could stand in for similar SB26 tweeters with a slight mod as necessary. I don't have the tools to design a crossover so would be dependent on an existing crossover, so I have attached the various choices. I'm open to using either the SB15MFC or SB17MFC depending on your opinions on each driver and your opinions on the crossovers in the existing designs that use them.
If necessary I could use a NRX part or one of the other SB26 tweeters, but the MFC version would be a little easier. Smallish room, lower listening levels, classical, opera and jazz, SE 2a3 tube amp which works fine with smaller 2-way bookshelf speakers. Don't need too much power or deep bass.

So hoping for some recommendations here. My all means include any other SB15/SB17 designs I haven't mentioned.

SB15MFC-08 midwoofer SB26ADC-04 tweeter. Sutantoroy
https://www.diyaudio.com/community/...tandmount-speaker-project.339276/#post5826477
https://www.diyaudio.com/community/threads/2-way-sb15mfc-08-sb26stc-04.315253/#post-6838731

SB15MFC -4 & SB21SDC tweeters, Xover 3KHz. "The Lockdown"
https://www.diyaudio.com/community/threads/sb15mfc-2-way-the-lockdown.374155/#post-6709256

Not sure how well SB15NRX designs would work with SB15MFC
https://techtalk.parts-express.com/...st-diy-build-sb15nrx30-8-sb26stcn-4-pic-heavy
http://www.audioexcite.com/?page_id=6373 Kensho 2

SB17MFC35-8 midwoofer SB26STAC tweeter. Bagsby The Tributes
https://meniscusaudio.com/wp-content/uploads/2015/11/Tributes-Write-Up.pdf

SB17MFC35-8 midwoofer SB26ADC-C000-4 tweeter Troels Gravesen 61-MFC
http://www.troelsgravesen.dk/SBAcoustics-61-MFC.htm

SB17MFC35-4 midwoofer SB29RDCN tweeter
https://www.diyaudio.com/community/...me-choose-a-crossover-frequency.266766/page-2

Again not sure how well SB17NRX designs would work with SB17MFC
SB17NRXC35-8 woofer and SB26STC-C000-4 tweeter.
https://www.diyaudio.com/community/threads/2-way-project-improvement.379112/
SB17NRXC35-8 woofer and SB26ADC-C000-4 tweeter. Troels Gravesen
http://www.troelsgravesen.dk/SBAcoustics-61-NRXC.htm
SB17NRXC35-8 and SB25STC-C000-4. Ralph's Chameleon
http://zaphaudio.com/DLR/

buongiorno,

this is my first attempt to use a ccs. it is for the driver section (EC86) of a single ended power amp with the 45.

I am unable to obtain a stable operating point as it vary with the variation of the volume control...

• volume control from zero to the first quarter: operating conditions are those highlighted in RED (8mA 1.8V 12V)
• in the transition from the red to the green zone the amplifier emits a bump in the speakers
• volume control in the central part of regulation: the values suddenly change to those highlighted in GREEN (6.3mA 1.1V and at the anode vary from 40v up to 80v and then down to 40V)
• in the transition from the green to the blue zone the amplifier emits another bump in the speakers
• volume control in the last quarter to full: the values return almost the same (highlighted in BLUE) to those of the first quarter of regulation.

strange thing is that the power amp sounds anyway, even with 12v plate voltage ...
what could be wrong ?

grazie!

Hello Everyone,

We can make a beautiful PCB boards with FR4 black core board,also we can make different soldermask like transparent,purple or the other colors you like...
If are interested in,you can contact us!

Sophia

Apologies for cross posting (I think I may have used the wrong forum when I posted my original message).

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

I’m new to the forum and would like to ask if anyone has an old Playmaster 132 that they’d be willing to sell. The design of the amplifier was originally outlined in Electronics Australia in 1971 (June, pp. 44-51; July, pp. 36-41; August, pp. 38-39 and p. 150). I don’t mind the condition of the amplifier (e.g., working, not working, in bits, parts missing).

The reason for my request is that I was passionate about electronics in my teens when the articles for the Playmaster 132 were first published. I couldn’t buy the parts at the time because I didn’t have the money. I’ve just recently retired from a career unrelated to electronics and I’d like to return to the passion of my youth. I’ve worked on a number of radios and amplifiers in the last year, but I yearn for the opportunity to purchase and work on a Playmaster 132.

If anyone can help me or give me some ideas about how best to proceed, I’d be most grateful. I’ve spent a considerable amount of time over the last six to nine months scouring various websites in Australia without success (e.g., eBay Australia).


Thanks,

Old Phoenix

I’m new to the forum and would like to ask if anyone has an old Playmaster 132 that they’d be willing to sell. The design of the amplifier was originally outlined in Electronics Australia in 1971 (June, pp. 44-51; July, pp. 36-41; August, pp. 38-39 and p. 150). I don’t mind the condition of the amplifier (e.g., working, not working, in bits, parts missing).

The reason for my request is that I was passionate about electronics in my teens when the articles for the Playmaster 132 were first published. I couldn’t buy the parts at the time because I didn’t have the money. I’ve just recently retired from a career unrelated to electronics and I’d like to return to the passion of my youth. I’ve worked on a number of radios and amplifiers in the last year, but I yearn for the opportunity to purchase and work on a Playmaster 132.

If anyone can help me or give me some ideas about how best to proceed, I’d be most grateful. I’ve spent a considerable amount of time over the last six to nine months scouring various websites in Australia without success (e.g., eBay Australia).


Thanks,

Old Phoenix

Loved the result when I built the Fane Sovereign 12-250TC plans posted by Scottmoose here:

https://www.diyaudio.com/forums/full-range/246746-12-range-fane-12-250tc-39.html

A friend sold me his pair of 12-250TCs for cheap and I couldn't resists. Now I have a quad of 12-250TC drivers.

Does anyone have any ideas how to create a twin driver box for two Fane 12-250TCs? Or an OB plan with two drivers per side?

Yeah, Ferrari dealers can be that stuck up.

Login to view embedded media

Hello all.
I am posting after a long time . First i am a complete noob on this amplifier thing.
2nd sorry if i did/about to do any mistake out of my lack of knowledge. I intend to buy this particular tda 7293 board because it is cheap and convenient.
100W Digital Power Amplifier Board TDA7293 / 7294 High Power Dual 12-32V Single Channel Audio Amplifier Module for DIY Speaker

3.62US $ 18% OFF|100W Digital Power Amplifier Board TDA7293 / 7294 High Power Dual 12 32V Single Channel Audio Amplifier Module for DIY Speaker|Operational Amplifier Chips| - AliExpress​

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a.aliexpress.com



My subwoofer is a 75w RMS old Philips one.
Can i drive it optimally with it?
I intend to run this amp with a 35-0-35 VAC EI transformer (yep i am mr. Cheap 😛 ). One of the top most priorities is to keep it economical .

Other options:
1. Tda8954th btl mode
2. STK 4048

PLZ help

Hi,
I'm looking for a 5.6mH inductor to buy. 5.5 mH will do. Need two.

Thanks!

I got a Philmore sa-2000 and I was wondering if anybody has any information on it or if you have the schematics. There is almost no information on it on the web.

I opened it up and it has 2 x 12ax7 and 4 x 6BM8 in a push-pull setup. All tubes turn on but there is a loud buzz that comes out from the speakers, even at minimum volume. The buz increases slightly at max volume but very little. The heaters are AC. When feeding music through it it is heavily distorded in the low end.

I’m wondering if it’s worth trying to fix or restore it. Does anybody know anything about the quality of this amp? Any schematic out there? I can’t imagine having some unique or proprietary circuit.

Thanks

Hey peeps,

i have a rokit 8 g2 monitor where something with the amp is broken. I want to replace all the inner parts with a class d and a dsp, as I simply want to start playing around with speakers, amps and dsps. So not interested in fixing the original pcb.

The monitor has 2 drivers:

• 1x Tweeter TWTK00012 with 4ohm and supposedly handles 20W
• 1x Woofer WOFK80156 with 4ohm and supposedly handles 70W

(Source: http://www.dancetech.com/item.cfm?threadid=4483&lang=0)


My idea on how to make them work again is to have following audio chain:



Now is the big question what kind of class d to get, i like the idea of getting china class d and play around with them.

For the 20w i found this class d from adafruit: https://www.berrybase.de/adafruit-stereo-20w-class-d-audio-verst-228-rker-max9744
But it looks crazily tiny and not sure if it really can handle 20w.

For the 70w woofer I found TPA3116D2 based 100W class d modules. It has a variable resistor on it with which i could probably turn down the volume
until i reach ~70W.

What do you think? Should that work? Any ideas? Problems i'm overseeing?


Thanks,
obsoleszenz

I have always liked the 14a was thinking using as a top for a 15”

Can anyone give me reasons for or against using this design? Has anyone built the 14a?

I don’t have a pair of WE555s and don’t want clone$. Can anyone suggest a CD driver that can be crossed over at 250-300Hz? Also under 250$ would be helpful.

I have heard tell that the angled connector to the we555 on the original design is critical, can anyone comment on this?

I have rough external dimensions and interior shape but not exact dimensions. Does anyone know where I can find these? A 1930 patent shows some things.

Thanks for the help!

I'm making a housing for a composite horn. The 10" driver will be in a small (barely bigger than the driver) enclosure, and I'm building a larger box to protect the horn and allow stacking and a pile mount (it's for events not home audio).


It will deal with a lot of SPL, but I was hoping/guessing that since none of the enclosure will serve as a resonant chamber, and I'm not going below 200hz With it, I don't need to buy specialized wood (void free Baltic birch vs Home Depot sanded ply).
that's my thought, but we all know what they say about assuming thing!

oh, and speaking of NOT resonating, any recommendations on what to use to dampen the box around the horn? Ideally something light.

What's up guys, I'm seeking some information on the output mosfets for this amp particularly the insertion arrangement.
It was started by another person but they pulled the outputs and I think they got it mixed up, so far I see the amps uses 640s and 9640s (the "s" is for plurality).
It's 5 pieces per rail on one side (10 pieces for complete rail plus/minus), what fets do I insert on the positive rail and what fets for the minus rail?

Focal in their top range likes to tilt their mids and woofers.
Is there any pro to do this?
Maybe time alignment or lobbing?

Hi All,

Does anyone have a copy of the Philips service manual for CD650, in English? I have seen a version in Dutch floating around the forum, but not one in English.

Thanks.

Does anyone know what the 2 ic’s are on the driverboards ?

Hi,
New member here. I have a Sansui G8700DB with a bad power lever meter. Looking for the board F3082. right channel works but not left side. Anybody parting one of the out who might be of help?

Selling this lightly used pair of Fostex FE126En that was put in a Frugal Horn Mk2 enclosure.

Asking $80 including shipping and fees in the US

Greetings fellow DIYers! Is anyone familiar with "Loudspeaker Shop" aka diyspeakers.eu? Their prices are competitive, I'm hoping someone here has a positive experience buying from them. Many thanks

The power supply was bad in this amp .

All of the original gate resistors survived but some are 60.4 ohm the others 47 ohm .

I know this is from the factory but should I switch them all to 47 ohm ? I’m replacing all 6 power supply fets along with the drivers and the two 8.2nf caps

Hello, I have to change the 4 big electrolytics in the PS of my Threshold Sa/3.9e.

What brand do you suggest for best sound/reliability?

In the forum 'Thresholdlovers' I find written:
go from Mallory (31000 microfarads / 75v) to United Chemicon Ucc (33000 microfarads / 85v) or RIFA (33000 microfarads / 100v) or CORNELL DUBILIER (xxx / xxx); add 4 Elna (470 microfarads / 100v); bypass with 4 Vishays (0.47 microfarads / 630v in parallel); change resistances from 10% to 1%; bias adjustment to 1.6.
What do you think?
Thank you.

Thanks

I am in the UK and have just purchased an early Cyrus 2 amplifier (Issue 04). The reason I bought it is because 1) I love restoring Cyrus One and Two amplifiers and 2) I've never seen a 120V model.

Seeing as I have a spare transformer from my 240V donor unit, I was wondering if anyone her could give me some advice on whether, in terms of resale value, it would be worth converting the amplifier to 240V or restoring and selling on the amplifier at its original 120V specification?

I would probably be putting the unit up for sale on eBay once it is ready so I'm hoping that, if it remains at 120V, it would pick up some interest from buyers in 120V lands due to the inherent rarity of 120V models.

On the other hand at 240V, these amplifiers restored still have a strong resale value in the UK and in Europe.

Any advice gratefully received!

Do ported speakers really act like an IB above the port resonance frequency? I’ve seen this quoted, but is it true? Has it been researched and is there any evidence? I’m wondering about this for the following reasons: an IB enclosure volume has an effect on the bass units performance (f3, transient response, etc.) At the port resonance frequency the hole in the enclosure will be “plugged” by the oscillating air in the port, but what if the speaker was reproducing a solo piccolo piece? Would there be enough low frequencies in order to set the port into resonance? If not, would the speaker essentially be an IB with a massive leakage?

Hello
Due to ongoing health issues I’m selling my matched quad of NIB TUNG SOL KT 120 tubes
This quad has sat unused since purchase from parts connection and are ready for a new owner to unlock their potential.
I am now asking $380 usd including shipping to CONUS.
The tubes will be double boxed and insured and I’m sure the buyer will be delighted.
I’m away from home until 5/3 and at that time I will post pics of these beauties.

Located in Oakley, Ca. pick them up, save $20 and you get a complementary door prize which won’t suck.Edited post as I had listed EH as the brand where these are T Sol
Thanks for looking today.

Hi guys,
Just bought a pair of markaudio CHR 70 drivers. I was planning on making concrete enclosures for them, but I then thought how could I do it easier save making all the wooden moulds. Then it struck me how about a 1m 160mm pipe inside a 200mm pipe, then fill the void between them with concrete with the top and bottom being capped off.
Any advice on whether to do a MLTL or ported, I was looking at the Mark 8 design a ported 1m long floorstander with an internal size of 112 x 160, hence my choice of a 160mm pipe, should give about the same internal volume.
Any advice would be appreciated.

Neil

Here is another project inspired by Danny: it is based on the same principles as the BoosterPhone, low supply requirements, rail-to-rail output on a low impedance, in this case 600 ohm and decent audio quality without too much complications.
It is designed to match older sources, delivering 150~200mV to modern equipments requiring 700mV or more. It thus mimics a passive step-up transformer, but without the impedance penalty: a 1:4 step-up transformer increases the impedance by a factor of 16, which can be problematic. Instead, the output impedance is much lower than the input.
Although the X-FoBooster requires a supply, unlike a copper & iron one, it has no power switch and lasts forever on a single charge: the supply current is comprised between 55 and 85µA.
First, the simplest version optimized for 3.7V:



This is the graphical version, based on the real prototype. The sim uses the native transistor types of the LTspice.

Now the 5V version:



Here is the non-inverting version: a bit more complex, but it has a self-centering quiescent output bias, and a THD of 0.03% against 0.1% (at 0dBm/600ohm, actually measured)







The values shown as comments are the ones used in the physical circuit. The others are suitable for the sim.
All the transistors are also 2SA1015/2SC1815, except the lower output transistor Q6, which is a BC547C.

The output is referenced to the + supply, and it requires a DC link to work properly. If it used on a cap-coupled input, it is necessary to include a dummy load of 1 to 2K.

I didn't build the various versions as complete projects, because I have no use for them (for the moment), but I breadboarded them, and the measurements are based on the breadboarded circuits.
The 3.7V version can use the same battery management as the Boosterphone, and it will last even longer

Got a little different project going some car audio.
I've obtained a new ute (little mini truck for my American friends) its a 2008 single cab flat tray Mazda BT50.
Just started working on it today making the sub box and planning out the door speakers... man I hate using fiberglass. Being such a small cab there is no real room for the sub in a conventional shaped box so Im making the box as a center console between the seats and it'll go up the rear cab wall to the window, I can only manage approx 30ltrs(1 Cf) of volume which is ok for most 10~12" car subs but Im lacking in width(230mm between the seats) so Im going to run 2x 8".
Parts list so far
2X Dayton UM8-22's
Door's will contain a Dayton RS225-4 for midbass duties, some Philips GTM 4" for midrange I've had them for years never used, and Im thinking of using some tweeters I've had for years also Jaycar response 19mm or the ones supplied with the GTM's.
Also have a Dayton 408 DSP to allow me plenty of adjustments and I'll be reusing an Alpine MRX-V70 5ch amp from my old ute, the UM8's will be wired for 2ohm on the sub channel and the RS225's on two channels and the GTM/tweeters on the remaining two channels, if there's not enough watts for the RS225's I will bridge the four channels into two and buy a small 2ch amp for the GTM/tweeters it'll all depend on how its measures when I get it up and running.
The Midrange and tweeters will need a passive xover made or I could use the ones supplied with the Philips GTM's... I'll have to do some testing/measuring may even end up buying some small coaxials or another set of 4'' splits(Focals would be nice).
Anyways that's where I'm at, I'll post up some progress pic's in a few days.

Hi all,

This is a bit more of a thought at the moment than anything.

I have a pair of alpair 12pw woofers lying around which were originally going to be used in a WaW set-up, but for a few reasons I don't think that'll be happening anymore.

I am curious about true ribbon tweeters and I'd like to see what they can do. I am concerned with using them in a two-way as I understand they don't usually reach too low.

The alpair 12pw can reach high with no issues, but I'm concerned about directivity if crossing about 3k+

I was wondering what everyone's opinion would be on this? The 12pw measures about 13cm from edge to edge, measuring from the edge of the surround. It's quite a flat profile cone, but there is no directivity data unfortunately.

My budget is only around £100 per tweeter so I was originally considering the fountek neo cd3.0 as I understand it's quite a popular unit

So in summary, I would like some opinions on the following:

1) Would crossing at 3-4khz cause noticable issues with directivity?
2) Are there any ribbons that can reach lower than typical?
3) I am also concerned about time alignment of the drivers and I don't know if I'd be able to do this passively. Any input on this is welcome
4) Any honest opinions welcome as this would be my first ever speaker/xover design. I don't mind some trial and error, as long as the driver selection is a good on paper and it has the potential to be a good speaker

Thanks

Hi,

I picked up a Yamaha XH150 which you guessed it is an high impedance amplifier, and I'm looking to see if you can mod it to an low impedance amplifier?

(I saw in another thread it was possible on a different 100v amp link)

I've attached the service manual that also has schematics.

Any help will be greatly appreciated?

Thank you!

I've tried email, and PM to no avail. I hope he sees this, if so, please PM me.

Thank you~
Gable

I am working on active crossover design for my speakers.Trying to figure out best way to take measurements.Unfortunately outside is not very quiet for measurements.
If i have to do them indoors what is the best way to get good measurements.

Hi !
I'm looking for 3-4 pcs LT8365 dc/dc conventer for battery power suply electrostatic headphones amplifier 🙂
I will consider any offer.

I'm looking to make a simple impedance buffer, something that has a high Zin and a low Zout - whilst avoiding the high idle power dissipation of a Class A design. I don't want any feedback (except for degeneration perhaps).

Power requirements are low (e.g. <10W) so cross-over distortion at low power is perhaps the limiting factor.

Candidates include double EF, Krill O/P, Sziklai buffered EF, Diamond buffer.

What would you recommend and why ?

Please drop me an email if you have a pair for sale.
hl5bxw@gmail.com

Hi,

I just finished my first version of a discrete dual opamp: Purple Gain.

Selling aca preamp open air version. It has a plastic film cover which broke when fixing. The pre works perfectly. Ship to Europe only
Price 180 EUR or best offer + shipping
PayPal is fine

Hi,

does anyone have (or know where to find) spice models for these tubes (6Э6П-E and 6Э6П-ДР)?

Hi, what would be the pros and cons of different materials used inside a box to reduce the volume. Would a bag of sand say be better than polystyrene blocks, considering the polystyrene has some give?
Steve

I am new this forum. I enjoy speaker building and have done several projects over 15 years, mainly based on 2 way designs (Dayton Audio projects and Madisound kits). Most recent is the CSS Criton 1TDX.
I am very intrigued by the idea of a full range driver speaker not using any kind of crossover network. I mainly listen to jazz, acoustic and "unplugged" popular music. I was thinking of the Pensil 10P as my foray into this world. I have enough 3/4" baltic birch (bought before the war) to make the enclosures. I would actually veneer thick (about 0.20") quarter sawn white oak in a vacuum press, making the panels even thicker and stiffer.

I have read that the Alpair 10P is "sensitive" to the choice of upstream components. In my case, my sources are a Rega Apollo CD player and Blue Sound Node, feed into a Schiit Audio Freya plus, feeding two Schiit Aegir amplifiers. Would this be a reasonable set up?

Hello everyone.

I have an aged Aragon D2A converter, as well as a (roughly) 12 year old eBay board purchased on the suggestions here at the time. I will probably finish that up as well, but I put the brakes on when I found this eBay listing. I like what I see, as far as board layout is concerned; they offer the proper power supply board (separately), which I would stick in another box with transformer(s), and pricing seems decent to me. Dual mono via completely separate chips; ganged together. Balanced output is attractive to me as well. The only "upgrade" offered is the "better" clocking module. I'd probably splurge for it, because I'm trying to get to a "last" DAC for me and my CDs.

Has anyone built, and more importantly HEARD one of these boards? I don't see much room for improvement in the components chosen- at least not enough to warrant removal and replacement. But, is it a good implementation? I can't tell- digital is well beyond my capability.

This will not be a "cheap" build, so I'd like some guidance from those more deeply nested in the digital decoding world, before I start ordering parts...

My father in law (now suffering dementia) has one of the pictured valve preamps built in a glass spherical shape. Can anyone point me to further information about it? Thanks!

wanted: TDA1541A S1 or S2 Crown

Looking for a Philips TDA 1541 S1 or S2 genuine part.
For a fair price.

Alex

Yesterday, we (4 of us) finally have time to do some listening tests on:

TDA1541A
TDA1541A S1
TDA1541A S2 (a real one, not a fake 🙂 )

in my modified NOS CD960.

The tests were done blind, so needed to teach my GF to how to pull and insert the TDA1541As, that was very very scary

The sound:

In conclusion, the normal chip has the most energy, the S2 is the softest, S1 is in the middle. Texture details were pretty much the same.

For pop music, the votes were divided, 2 of us prefered the S2 version and one liked the normal version, the final one liked the S1.

For jazz music, again the votes were divided, normal and S2 received 1 vote each, except S1 received 2.

For classical music, 2 prefered the S1 version and 1 liked the normal version. The final one couldn't decide between normal and S2.

So in summary, the score line is:

.....................Normal......S1.....S2
Pop...................1............1.......2
Jazz..................1.............2......1
Classical..........1.5...........2.....0.5
---------------------------------------------
Total................3.5..........5......3.5

As you can see, the results were a bit of surprise for us , we thought that the S2 should win hands down, but I guess you just never know what will happen in blind listening tests.

So "in our system" with "our ears", overall we prefer the S1. Of course, this is by no means conclusive.

Wouldn't it be nice that one can switch between normal, S1 and S2 on the fly ... 😀

P.S. Just a side note, to be perfectly honest, when the tests were done blind, the difference in sound was quite small, I really would not lose any sleep over it, whether my system uses a normal, S1 or S2 version. But for now, S1 will stay.

New ad listed, updated.

So the question is what can you do when your manifold for an IB sub is too big for the wall space available? In the particular situation I am looking at the wall in question has built in book shelves and cabinets over most of the area. Of course you could remove the cabinets or bookshelves but the powers that be would be unlikely to approve. So there is several inches of space below the cabinets. So one wonders if you could use that space as a snout for entry. It would kind of resemble an odd slot loading or a bandpass of sorts. I am not sure how to model it in Hornresp but perhaps something like a MLTL but only the port enters the room.

Thoughts?

Has anyone found a good source for output filter inductors for class D amps? Winding sucks! Thanks.

My 20y? old NAD 502 has developed a problem: after closing the drawer, with or without CD, nothing happens. No spin, nothing. After a few seconds the drawer opens itself again. This problem increased over time and now the issue occurs all the time.
I cleaned the lens, with no effect.
Any suggestions what to do?
I know it’s not economical to spend much money and I’m not sure I would go down the route of exchanging the entire laser unit. However, there is some emotional value in the old NAD….
Thanks!

What about quality and live time expectancy of this unit especially concerning the laser unit (optical pick up) ?
http://jmf-audio.com/dmt37_en.htm
https://6moons.com/audioreview_articles/jaysaudio/4/

Long live laser units for CD use only there was not many.
This included only certain models from Hitachi like HOP-M3 (DENON Linn Karik), Sanyo like SF-91 (Cambridge Audio CD-4/CD-6(CDT), Optima Series from JVC, used also in Japan's best available transport JVC EXU-901a - go to
https://www.diyaudio.com/community/...ct-1-ct1-better-than-vam1254-cdpro2lf.149032/
and Philips CDM-0, CDM-1, CDM-3 and professional versions of CDM-4.

By far the shortest lived laser units were those from SONY KSS-series, even such from top class cd player devices like SONY ES series and Accuphase (e. g. KSS-272A, KSS-274 KSS-190A).
This is the reason, why retail prices for NOS versions (new old stock) are up to € or US-$ 2,500 (!!!).

A friend of me want to buy a SACD capable CD player and have heard from others, that models from brands like e. g. Shanlin Ayon, McIntosh, Project despite very high purchase prices are very unreliable.
The reason therefore is the fact, that the equipped mechanism parts, especially the optical pick up it is the cheapest available for the mass market - check out this URL's:
Price replacement parts:
https://www.ebay.de/itm/265606415758?hash=item3dd760458e:g:JpcAAOSwPLFiOHOk
https://www.ebay.de/itm/265604093786?hash=item3dd73cd75a:g:cYMAAOSwUnJiNpOQ
https://de.aliexpress.com/item/32415646038.html
used in CD-PRO 8 from StreamUnlimited
https://www.project-audio.com/wp-content/uploads/2019/04/CDBoxRS2T-EN.pdf
https://www.audiosciencereview.com/forum/index.php?threads/lets-talk-cd-players.9104/page-6
Login to view embedded media The fact that the mechanism's backing plate was replaced from a solid block of metal milled from the solid, doesn't extend the lifetime of those parts that are in use in a DVD player that costs less than lunch.

Post #4, #6 and #8 under
https://www.diyaudio.com/community/threads/streamunlimited-dedicated-to-high-end-cd.337527/
don't gives little hope, that the situation here will improve again especially in order to SACD playback.

But maybe the transport mentioned in the headline is like one know it from earlier times of the CD era - possibility there are some experiences in the meantime. Thanks for comments.

P.S.: I would still trust JVC the most here, since older DVD players from this brand also have no problems with short-lived laser units (and vintage cd player models from this brand with OPTIMA units also still works).