Freeze spray is pretty expensive to me ($10 for 4 ounces free shipping) and not available locally and ordering from a place with shipping charges makes it more so

canned is is easier and cheaper to get

canned air when used upside down is supposed to be like freeze spray

has anyone here tried that approach?

I would like to avoid shipping this for repair unless it's absolutely necessary. Is there a recommended repair shops page here? Looking for repair shop recommendations within a 200-300 mile radius of Los Angeles, CA?

I picked up a Yamaha B-2 VFet amplifier last year and it sounds wonderful, but sometimes I get distortion on 1 channel and sometimes the sound takes turns between the left and right channels for a second or two. This latter problem is normally at softer volumes, while the distortion is more at higher volumes, with for example, chords on a cello, that may have a hint of dissonance.

My Yamaha B-2 was slightly damaged (casing) when I received it due to the shipper's poor packaging, but everything worked fine at the time, but as I use it more, I am starting to notice that it does need some love soon.

I've called a few repair shops and some are very honest about whether they have worked with this particular amp, while others seem to use some sort of fear tactic. They keep me on the phone and make feel like if I don't bring it in right away to THEM, it's going to blow up.

I know this is a DIY site. I have built 2 of the ACAs, but I wouldn't be able to do that without the amazing step by step instructions on the site. I have the Yamaha manual, but I just don't trust myself with this. If I break something, I just broke my wallet.

Thanks! Any help is appreciated.

Sale GU74B — 100 pcs. for $400 ea.

Hi All,

I have started this thread to post circuits and block diagrams for this project.


This what I am thinking the amplifier layout will look like, the size of case will be base the size circuit boards.

The Power LDMOS Transistors I thinking of using are the MRF101AN and the MRF101BN made by NXP, therefore the cost to start with will be high as device are somewhat expensive. But it is possible to run them at 10 MHz switching speed, making it possible to pass through DSD 64 and DSD 128 without conversion.

Tested basic PDM ADC, using a 74HC74 D type flip flop, I will need to improve its performance by adding in a negative feedback loop.


As you can see there is nothing to it, as for the 1.8432 MHz oscillator goes, it was what I had available to use at the time to provide the clock signal.



Wave forms:

1. is the PDM Q output from the Flip Flop
2. is the Clock input
3. is the sine wave from the output of the low pass filter
4. Is the 4 kHz input sine wave from the signal generator

From the block diagram this would make up part of the ADC 2 input stage to the FPGA, with a few improvement.

This is a project that will take some time to develop as there a lot more to workout before I even start to think about a PCB

Hello everyone,

I got a pair of elipson Melodine 4 from a friend. One of them is fine, but the three drivers of the other one are out.
I have a really hard time finding information on the midrange (Vifa K10MD-09), I only find the K10MD-19 datasheet, but I don't know if they are equivalent.
I found a small datasheet for the woofer (C20WG-09).

Both parts are unfindable for sale, so I'm looking for replacement ones. Do you have any idea on which could do the trick ? As my other speaker is fine, I really would like that they continue to sound the same...

Thank you in advance for you help!

Alex

I'm looking at this newly custom built tube phono preamp. It has a separate power supply. It has a bit of hum.
Here's some pictures.

The first thing I'm suspicious of is how there are two ground points. Most tube amps I've seen have a single ground connection to the chassis and it is at the input terminal ground.
Does this seem like a good starting point? Does anyone notice anything else?

EDIT: no further replies required.

found 4 pairs of BD313/314 , most likely for a Radford HD250, plus one pair of rca 40409/40410. all new.

any one interested ?

Hi!

How do you guys measure the phase margin of an amplifier?

I don't want to make an amplifier that risk becoming unstable, and I don't want to overcompensate the amp with a too low dominant pole. Without access to a network analyzer, how do you do this?

I found an article here that describes a method for measuring the phase margin of a power supply feedback loop, and I suppose this would for for an amplifier also. They are using a transformer to inject a signal, what type of transformer do you think would be suitable?

I suppose a good indication of stability can be made by looking at the response to a small signal squarewave. If it rings it's phase margin is probably too low, right? But is this method accurate enough?

Anyone here who can point me in the right direction?

Regards,
OJG

I tried those Autoformers in my tweeter highpass and I am more than pleased with the result. They are on sale now so might be a good opportunity - I have ordered 2 more pairs already.

They eat up 2-3db more top end than expected in the 10-20k range, which must be taken into account when adapting the filter. I could not measure any distortion at 2 amps and the sound is indeed very mellow - the perfect match for my titanium tweeters.

Hi community,

I'm building a karaoke setup with the components as seen in the image attached.
The problem is that even with the mic preamp the volume of the Mic is about half of the volume of the other channels. I'm looking for a way to get the inputs for the mixer at roughly the same volume.

The datasheet of the preamp can be found here. It says that the preamp has a fixed gain of 18dB which could be increased to 40dB if I understand well. I've removed the pre-soldered resistors and tried a few different values but this didn't increase the gain.

So now my question is:

•Should I be able to increase gain by setting different noise gate and compression values by changing the resistors?
•Is there a(nother) way to increase the gain?

•Assuming the phantom power supply has balanced xlr output, of which I now only use hot and neutral to get mono, could I increase input level to the preamp by different wiring or additional components?

•Any other solutions, like different mic-preamp or a simple way to reduce the input signals of the other channels...etc?

Sorry for the noob questions, I'm learning by building and help is much appreciated.
Thanks in advance and rspct to all audio engineers all over the world!

-Malik

I had one of these, made here and very, very sold.
It was highly recommended by DJs in the 70's for its strength,fortress . Pulley traction. There was a little problem that can be seen in the design of the tonearm. Let's see if they discover it, there are no prizes for first place (whoever gets it right first), just the satisfaction of being recognized as an "expert" in TT. 😊
I can't really say that about the author of the Wikipedia article......I would have chosen another photo of a TT to attach to the article ! 👎

https://es.wikipedia.org/wiki/Tocadiscos

There is no English version, but GT will translate it, although it is not necessary, just look at the pictures 😉

Dear Friends

I am trying to fix an old Kenwood KA-59 amp and badly in need of the schematic for this amp. I would be very thankful if anyone who has this schematic, can forward me a copy.

Thank you in anticipation

Carlosraj

I'm looking at modelling some two-way speakers that will be placed on a 24" wide shelf next to a TV.

Normally a two way driver is modelled with the microphone in line with the tweeter and then the woofers' acoustic Z offset is determined.

At one stage Mission used to have speakers that had the tweeters at the bottom which to me seems to be logical: A mid/woofer will start to beam at higher frequencies while a tweeter has wider dispersion. As such it seems logic to me to want to listen at the woofers' height.

It also seem to me, but might be mistaken, that if the speaker is to be modelled with the woofer on top and the microphone in line with the woofer that then less Z offset required and hence results in a different crossover.

Am I correct in this assesment and are there disadvantages to having the woofer on top that I overlook?

Thank you for your input.

Hi everyone,

the 15" eminence beta drivers were happy in a OB and now I'd like to try them in a sealed enclosure. The problem I am having is for a flat response the Vas I get is ~600 L and the recommended volume in the spreadsheet is 45-62 L. If I go with a higher damping factor I can have a smaller box, but how will this influence the sound? What volume would be a good tradeoff?

to follow my steps:
decided on a Qtc = 0.707 for a flat response
Qts = 0.58
Vas = 334 L
Volume of the box (Vb):
Vb = Vas / (( Qtc/Qts )^2 - 1)
Vb = 334 L/ (( 0.707 / 0.58 )^2 -1)
Vb = 687 L

If I turn it around, for a Vb of 62 L what damping factor is needed?
Qtc = Qts sqrt(Vas/Vb)+1)
Qtc = 1.47

A higher Qtc, will mean a smaller volume and a happier wife, but the frequency response will not be flat. Is that all there is to it here? I've been reading on the web about boxy sound etc. but can't find any good resource where these things are explained. found this link below quite useful, but it also doesn't go into explaining why the sound is worse. the example for a ported box:
" A ported enclosure will produce louder deeper bass at the expense of sound quality." Speaker Box Enclosure Designer / Calculator Help

any advice and help is welcome 🙂 I can also just try it and go with the max size acceptable for the space we have ~120L and hope for the best 😀 If the speakers are not suitable for a sealed box, would be also interesting to hear before I start building sth that should not be built 🙂

Thanks,
Martin

Hello,

As my first complete LTspice -> KiCad -> PCB manufacture project I wanted to remake my damaged driver boards for a Sansui AU-999 integrated amp from the early 70's.
I wanted to see whether there are any circuit improvements I could implement into the new PCB and I wanted to ask you guys for a bit of help in trying to achieve this.

I'm attaching the original circuit schematic for the amplifier, the F-1159 outlined circuit is the driver board I was aiming to rework.

So far, the possible improvements I have identified are:

1. Adding a Baxandall diode to the quasi-complementary output stage - could someone advise on the best location? You can see I already attempted to implement this in my schematic, I tried different configurations and this one is giving me the lowest THD figure. It was done purely by experimentation and looking at other qusi-comp circuits.
2. Changing the value of output pull-off resistors from 220R to something smaller as suggested by @steveu in another thread - The suggested 47R seems to give a good improvement in THD and helps improve the x-over distortion
3. Adding a small value resistor in series with the 15pf feedback cap - steveu also suggested adding a small resistor (100R as starting value) to the feedback cap to prevent RF from getting into the LTP input transistor
4. Adding current limiting - suggested by the same user, what and how simple it would be to implement.
5. Improving the input differential pair - this is something I wanted to investigate, would adding a current mirror/source be a simple matter with the existing configuration?
6. Adding op-amp-based DC servo - this might be too much for this project as I would need to add step-down regulators to create a dedicated bi-polar PSU rail for the op-amp to operate, I'm not sure if that would be worth the effort?

I would be grateful for any additional suggestions or help with the above,
My knowledge is still very basic but so far I've learned quite a bit from this project and I really would like to see it completed.

I'm attaching the original amplifier schematic along with my LTspice files, inc. custom libraries.

Thanks for looking into this!!

I currently has 1x18" and 3x12" subwoofers. and assembling a second sealed 18" sub. I am pretty happy with my bass and set up, hopefully happier still with 2x18"m and 3x12". In have two BMS 18N862 subs and 3 12" Sonus faber Cremona Subs

My thinking is I can sell on my Sonus Faber subs for probably over £1k each easily, they were £3k+ new and a very good hifi sub. However building a sealed 15" with a construction similar to the 18" I have built will be more rigid no doubt, plus I can increase the cone area by 60% and focus on speed and slam by using a lightweight 30 something Fs driver and targeting 35-80 Hz with a very efficient lighweight driver. The SF subs are designed to go low in a smaller enclosure and I dont need them to hit the lows as thats for my 18's primarily. I would value views on driver options so far I am thinking of something like the Faital Pro 15PR400, the SB Audience 150B350 or even the Eminence 1525 Legend. Internal volume will be something like 90L and made with 25mm Birch Ply, heavily braced. I have the amps, so its probably under £3k all in to build 3 depending on driver cost and the number of 25mm sheets required. So its more of a swap financially !!!

The cabinet will be 90L or so and a smaller version of this, my 18" unit in assembly.

Hello Everyone,

I came across an old (1995) article from Stereophile magazine, about vibration control. Thought this is a good read.

https://www.stereophile.com/reference/52/index.html

I have the schematics and parts list that can be found online as well as the XL-280 service Manual. Anyone have an original or PDF of the rest? Thanks Much.

I have recently purchased a 40s battery powered 4 tube radio, Well, The chassis without the box. I would very much like to recap it, But I dont know enough about electrical engineering to make out the rating on the paper capacitors and translate them to modern values. I know not to touch the micas. It seems to be an all dc radio with no means of accepting an ac input.
The tubes are:
1A7GT Oscillator
1N5GT IF Amplifier
1H5GT audio demodulator/ first audio stage
and finally a 3Q5GT as the power amp.
The radio wants two voltages in, a 90v 12ma max tap for B+, and 1.5v .25a amp to the filament voltage or A+. With a stated max output of 250mw to a 3.2 ohm voice coil in a permanent magnet speaker.
The datasheet I found states it has 12 capacitors, most of which are paper.
C-1 Paper .1mf 200v
C-2 Paper .05mf 400v
C-3 Variable tuning cap (do these go bad?)
C-4 Paper .01mf 400v
C-5 Paper .01mf 400v
C-6 Mica 100mmf 500v (This one is most likely fine because mica)
C-7 Paper .002mf 400v
C-8 Paper .005mf 600v
C-9 Mica 100mmf 500v (another mica to not touch)
C-10 Electrolytic 10mfd 150v
C-11 Paper .005mf 600v
C-12 Paper .5mf
As far I I am able to wrap my head around the mfd is analogous to the ever present µF that seemingly everything these days uses in abundance, the mmf ratings listed are somewhat irrelevant because mica caps dont really go bad, well, Sometimes they do as is with everything eventually, But it is somewhat rare.
So my main question here is how do I read the values of the paper capacitors, and what do I replace them with? This isnt the only tube project I have, but it is the first I feel comfortable actually tackling, seeing as how the voltages are "Relatively" low.

Hello all:
I am making an RH84 version2. I have a question about my power supply.

I am attempting to salvage a used transformer for the B+. This transformer has multiple windings. The B+ winding is 630vac with no centre tap. My target voltage is +- 315vdc. I have read from the hammond site I should expect ~ 45% of AC with lots of ripple from a halfwave rectifer. So I thought this would work and have room for smoothing.
I am trying to use a beautiful 5U4gb I have in a nice ST bottle as the rectifier. For some reason I get 500+ volts DC.

I have one leg of the transformer going to both pins 4 and 6 of the rectifer. The other leg is (-). The heater transformer is connected to pins 2/8 and floating with CT not connected. B+ is drawn from pin2 into 35uF>13ohm>330uF with a 220kohm bleeder. B+ went up to +- 530vdc before I shut it down, I did not wait for it to stabilize as I am using 400v caps. Next I put a pair of 5408 diodes between the transformer and the rectifier thinking it would help, same result?

I am perplexed with what to do? or what I did wrong? Is the problem with using the 5u4 as it is directly heated? Any thought would be helpful.

Note:
I am pretty new at this so try to be gentle with your comments

I have already completed the chassis work. (I got a bit ahead of myself with that one. It looks really nice by the way.)

I am hopeful this can be sorted out with a little help.

Thanks in advance

I was doing some noise measurements with OPAmp available on a market, and discovered that NJM2122 beats up any other OPA that I tryed to evaluate.
I mostly interested in low frequency end, even in 0.1-10Hz for methrological purposes (oscilloscope pictures), but it doesn't make difference - spectrum is the same up to 20 kHz and above.
Have a look:

Hey all-

I've got a ST1000A but it's been forever since I used it. I need to fabricate a new 'detector probe' - does anyone know the ST recommended design? I have not found it.

I made this one yesterday from a drawing I found in an unrelated document - no joy. Thanks for any input you have!

FS Mezmerize B1 buffer

I'm going in a different direction so am selling this B1, it's 99% built with matched jfets purchased from the diyaudio store, all it needs are the fets ( included ) installing a volume pot, transformer and it wiring up. I will include the recommended Lorkin selector switch and optional heatsinks.

£120 plus postage at cost anywhere in the world

Dear DIYers,

I have developed a system identification /adaptive filtering approach FSAF, which (R2.0) is capable of speaker measurements using any excitation, such as music.

The main advantage over MLS/chirp is that FSAF linearises the loudspeakers at the true working area on real signal, and produces a non-LTI (Linear Time-Invariant) residual which you can examine both visually and aurally (.wav) in "fine print".

Here is ADAM F5 on 1 min from Mozart Piano Concerto, at 80dBSPL@1m:




https://www.mathworks.com/matlabcentral/fileexchange/83363-fast-subband-adaptive-filtering-fsaf
You'll need to read fsaf.4.pdf chapter 3 for spkid.m methods descriptions.
The same chapter also contains comparisons with old MLS / chirp methods.
You don't need to understand the underlying math to run the spkid.m class functions.
The license for FSAF is GPL.
The home version of Matlab costs $75, plus sigpro toolbox.
You may be able to run the spkid.m in Octave with some modifications (I have not tried it).

Hope it helps,
MZ

What is the difference between generic PVA glue and Evo-Stik Resin W Extra Fast Interior Wood Adhesive?

I get the impression that PVA glue is more "watery" than Evo-Stik and it is certainly cheaper but is it better / worse, more or less suitable for speaker cabinet building? Since it is more watery I guess that PVA glue may spread better? Evo-Stik is water soluble before setting, can it be "diluted" before use?

Also, many speaker cabinet DIY instructions strongly advise you to use PVA glue, some advise you to "glue and screw" - should one just glue or glue and screw? Would screwing distort / buckle panels or battens?


EDITED - Just answered my first question (LINK):
Q: Is your wood adhesive based on PVA?
A: Yes, both Wood Adhesive Extra Fast (Resin W) and Evo-Stik Wood Adhesive Weatherproof are based on modified PVA emulsions

I am still curious as to whether one can "water down" Evo-Stik and whether one should "glue and clamp" or "glue and screw"?

I've been looking for David Manley's "The Vacuum Tube Logic Book".
If you want to sell your copy or have it in soft-copy please let me know.

Thanks,
Steve.

So I've been having fun building some braided power cables recently after listening to Paul 'PS' McGowan extolling the virtues of a good braided cable. He's right, the braid mitigates/reduces RF.

For one of the cables I'm using Lapp ÖLFLEX CLASSIC 110 CY 3G (1,5mm² DIA) in a 3 cable-run braid geometry and combining the individual conductors in each run into a single one to give an overall conductor diameter of 4,5mm².
Why waste any copper by only using a single conductor from each run, right? Or wrong? Is this going to facilitate too much current draw and cause any issues? I'm assuming not and that conversly, having too thin conductors would cause issues, especially if used for hungry amps etc.

i.e. I suppose I'm looking for a confirmation that there are no disbenefits to combining all the conductors into a single thick conductor for each pin of a power cord.
I'm also using a slightly thinner gauge cable for a different model giving an overall 2.25mm² diameter for each conductor.
Thoughts?


Some pics.

This is the cable with 4,5mm² dia conductors.





This is the cable using slightly smaller 2.25mm² dia conductors.

Pictures are showing what's for sale.

Price: 250usd / euro

Location: Sweden

Best regards. Bengt Dahlberg

PM if interessted 😎

Edit: I finally found all documentation that came with it as well. 🙂

Edit again: Dropped the price at another site to 250usd, same here as well of cource.

I am building a Karlsonator 8 with fostex fe206en at the moment. I read many articles and threads discussing the benefits and drawbacks of this design and discussing the suitability of certain drivers. But I am still not sure I understand how it works.

Am I correct in my understanding that it is a double bass reflex with a front chamber with an aperture that functions as an acoustical lens that improves off axis listening.

Am I right or wrong....or partially right but are there more acoustical principles at work?

Have anyone done it? I saw it in the PA world. My living room is reasonable small, doing this will preserve space at maximum possible. The small top speakers will be hang in the wall also. I am intend to minimize the weight as possible roughly ~25lbs or less.

NAP140/NCC200 clone with onboard PSU.

Clone of NCC200, but without output inductor.

Schematic doesnt contain the correct values yet and not all the caps/transistors are the right ones. But I wanted to get most of the layout done first to get a feel of the size of it.

Size is about 22 x 12 CM.

Hi!

Could somebody please help me understand the u parameter for pentodes as specified in datasheets? I see this:

I tried googling, but failed miserably 😳.
Thanks!
Jose

I Just want to express my gratitude for how great this driver plays into my TL that was designed for eikona. Time ago eikona was replaced by tang band and now with Pluvia. Not designed for the pluvia but i am speachless how good It Is developing in terms of nuances and delicacy.i use them for vocals+Guitar music and i dont Remember a driver giving me such a pleasure .next week a wood builder Will delivery a pencil speaker to accomodate maop 11.2.
Not sure It can sound Better thanx this pluvia but Hope Is high.only then i Will know if the actual pleasure come from the special voicing of the pluvia (jazzy?) or what..Will report back of course...enjoy and as a disclaimer i am not connected at all with MA team

Hy,
I'm looking to buy new amplifier for living room (around 20m2).
Currently I have a pair of old Pioneer CS-770 speakers, those will also be replaced a bit later, so they dont play a big role. But I will likely get something in similar size and power rating.
I listen mostly 80s & 90s rock, hard rock, pop. I used to listen to alot of electronic music, but as I'm getting older I'm moving away from it. But I still do like to shake the house from time to time.
This will be my first newer quality amplifier and I'm not sure what to expect. I want rich sound and bass cannot be sacrificed.

I'm looking at Yamaha A-S501 and Marantz PM6007. I'm also open to any other suggestions in this price range, but I must see if I can get it localy.

I like the looks of Yamaha better, but that is it for now...
I know nothing will be "the best of the best" in this price range, but I would like to hear opinions.

Thank you

Anyone got a spare power supply to fit a Linn AV5125? It's the same Class V 08/02/02 version....

So I just got my SA-36 but it's the TDA7492PE version.
I opened it and it has 2 4400uf 16v capacitors. Would there be any benefit in swapping them for 2 4400uf 25v ones? And can I have those 2 and add a 2200uf 25v extra?
I'm currently using a laptop power brick 19v 3.41A but I'm guessing it's not delivering all of the power. The chip is supposed to handle up to 26v.

Will post pictures of the replacements I bought.

Hello there.

Cannot find inductance locally. Where to get iron core for a 36mH one?

I need to do a passive high-pass for a full range speaker design. Pointers to already-made al welcome, but I can measure inductance so I am not afraid to wind a coil.

Thanks!

Am repairing an A5002 with broken, non functional speaker selector pushbutton switches.
An odd duck, these switches are, with a offset bracket to mount them.

Suggestions for a good retrofit?

Hi all,

I'm busy designing a subwoofer to be used at the scuba diving team "watering hole" clubhouse. It's a fixed installation with 4x JBL EON712's used as tops. I have space to fit 1 sub of about 1x1x0,7m. Normally this is used for background music, but we also have parties about 5-6 / year. Total floor area is about 80m2, total volume is about 240m3.

For now I have a 500W amp and plenty of DSP (DEQ2496) available to drive this.

I was looking at the THAM 18 and just for fun I decided to scale it up by 1.167X and sim it with the Beyma 21QLEX1600fe. Sims look really good to me.
Is this a totally stupid idea / am I missing something. Or could this be the sub to really pressurise the room if we want to?

Any toughts appriciated!

I found this on tntaudio. Views?

https://www.tnt-audio.com/casse/tweeter_theory_e.html

Greetings all. A good friend had this Welborne Labs 5v Squeezebox PS kit laying around and asked me to assemble it. The kit appears to have all the correct parts, including transformer, for the Squeezebox 5v power supply but the board supplied is incorrect. The supplied PCB is too small for the supplied components and the enclosure. I searched for Welborne labs squeezebox schematic but nothing popped. I was thinking of getting a board made or doing point to point. There is not much room under the board so a PCB would be the best solution with supplied enclosure. Any suggestions?

I attached pics of the kit with incorrect board and an assembled squeezebox PS pic snagged from the internet. Welborne labs is long gone so no help from them.

Thx.

Looking for a newish pair of Blue Hemp ANJ’s. Nothing too Dark. U.K. Thanks.

I am uploading pictures of my rebuild, recapped and refurbished Onkyo M-508 power amplifier.

Hello guys,

I am new to this forum and i personally found this forum very helpful and helpful people.

I am rebuilding recaping my onkyo grand integra m-508 power amplifier. I have already replaced main 8 filter power capacitors with 100 volts 10000uf cornell dublier capacitors. All other capacitors i bought are elna silmic ii nichicon fine gold nichicon muse and Panasonic fm.
I want to know that originally at c413-c416 there is nichicon muse 16v/10uf polarized caps and these muse caps are not available anymore only nichicon muse es bipolar are available in that value so i bought nichicon muse es bipolar caps instead of polarized capacitors. Can you people help me telling can i use bipolar nichicon muse es caps in that place instead of polarised?

My other question is can i replace c463-c466 polarized 3.3uf 50volts electrolytic caps with wima film caps?

Picture added of factory fitted nichicon muse polarized capacitor (green ones)

Help will be highly appreciated.
Thanks

I recently built MJK's OB speaker and am interested in adding a tweeter. I used the Eminence Alpha 15 A and the Fostex FE108EZ. I have a set of Tymphany BC25SC55-03 1" square frame tweeter from another project that I temporarily hooked in series to the full range driver just to see how this would impact the sound. There is no question that having this pointed to the ceiling added to the top end. That was a quick test and I removed the tweeter. I am hoping others have done something similar and can share with me the tweeter and crossover they used.

​

New in the box Little Bear T7 Tube buffer/RIAA preamp. My brother purchased this, but then traded it to me for a modified NAD integrated amp. I was going to mod it, but never got around to doing it, Totally new, stock, never even listened to. Some time along the way I lost the owners manual.

Prefer CONUS sale.

Asking $39.00 plus shipping.

Firts of all i just wanna say hello everyone.


Im confused this class d amp icepower 50asx2 no signal/no output. When i use multitester on speaker out then tap input pin there is signal. But when speaker connected no response. I try to bypass L100 inductor no luck same issue. Is there someone experience this issue.

Thanks and advance.

This DSP has a 12v adaptor plug but is 12v the hard maximum DC voltage or can it take more? I'm building a 12v LFP battery pack to power a trailer speaker but as it's LFP the actual voltage will be around 13.2V to 13.4V most of the time.

...

Hello everyone Please help me to switch the voltage of ml 360s to 230-240v. Who does not find it difficult to find a pad behind the sticker, pull it out and ring the short-circuited jumpers. Please help, I'm afraid to make a mistake with the voltage transfer myself.
Just write down which pins you have closed with each other.

There is a "big issue " about this reel many complain about the same problem which is slow RW and FFW when you wind the tape on any side the "engine" runs out of steam and often stops completely Obviously at this condition or even with less tape loaded between the reels starting RW or FFW respectively has also no effect Engine dont have the power to start.

Many post questions about it, and looks like a design flaw rather than a damage Still there is an other internet urban legend regarding a couple of resistors that fail (never found one failed though ) but of course winding problem has absolutely nothing to do with it .Yet again no matter the plenty questions or the urban legend nobody seems to come up with a solution .

I dont understand why this is happening on the internet . People that have no idea about electronics post solutions related to the blue resistors that obviously have no effect one the specific problem .

Anyone with ABC knowledge of electronics will see in the first minute that the blue resistor with one 1N 400X diode is there to consume the reverse voltage produced by the motor when spins free on the opposite direction . you don't want this reverse voltage against your drive transistors ...Alike protection diodes for reverse current to any transistor operated relay drive circuit .
You might have issues there but none of them is related to the slow REW or FFW problem . period !!!


Face it !!! the design has a flaw ...

Real reasons that might cause the problem
---Dirt and tape left overs all over
---Age problems regarding capacitors/resistors/contacts on the psu of 18.7 volts
---Aging of the motors
---Fatigue on the plastic gear ( created by spinning belts)
---Problems on the belts
---Tape/reel itself related issues
---Remote but possible: alignment issues
---In general and even though the design looks pretty cool problem remains that tape travels through a lot of barriers to end up in the other reel and that on its own is an issue .

Now you may choose any of the problems and any possible combination between them and you will end up with a slow wind speed ...Often its so slow that either the tape will stop completely winding at some point at the end, or if needed to start winding while some amount of tape is winded in the other reel then start is impossible .

There is a vanished guy that offers a fix but as far as i know this guy doesn't answer email or takes too long to ship parts or what he calls kit ....

Got it fixed permanently !!!
The way i did it offers

---No more than 5 euro of parts and one hour of work
---Increases wind speed side to side by far
---Reduces stress on belts and plastic gear
---Will work the same well even if belts inside are very loose/old
--- will be able to start in very high speed at any position of tape or type of load
---It will work extremely very well even if tape drive is dirty or belts are old or power supply has age issues or motors have age issues

Most of all has absolutely no side effects either in electromechanical points or from any sound or any other aspect ...

Kind regards
Sakis

Hello.
I bought a cheap Cambridge Audio Azur 840A amplifier. It goes off by itself between 2 and 15 minutes. CAP5 system says nothing.
In factory service menu all counters is OK.
I opened the amp and there are two capacitors C25 and C26 inflated a little.
Can it come from that?

Service manual

https://mega.nz/file/AThnRLIC#pw_XPcdZj1O5gSE7jPfl8sCsuQDRpYkN3DNUdBRpF3E

I have two of these Clairtronics 120va 2x 120 primary 2x 18v secondary transformers for sale I don't think these have been used. Please see pics for details

£20 each plus £10 postage. UK only

I'm repairing a Marantz 2220B for a friend with dead output transistors on one channel, which needs to be replaced.
Anyone willing to part with one of each for a good cause?

Again:
1x 2SD188
1x 2SA627

I'm buying or we can trade.

Trading.
I have tons and tons of new never used (stock) high end op amps + some discrete Melcor 1731 op amps, potted by yours truly. (photo attached)

Discrete Melcor 1731 op amp, with Mill-Max gold-plated pins. Potted.
AD797 - Ultralow distortion, ultralow noise single op amp. DIP-8.
AD8620 - Wide bandwidth dual precision JFET op amp. SOIC-8 or mounted on a DIP-8 adapter with gold-plated Mill-Max pins.
AD8610 - Wide bandwidth single precision JFET op amp. SOIC-8 or mounted on a DIP-8 adapter with gold-plated Mill-Max pins.
AD712 - High speed, precision dual Bi-FET op amp on DIP-8 adapter with gold-plated Mill-Max pins.
AD827 - High speed dual op amp. DIP-8.
AD845 - Fast precision CB-FET op amp. DIP-8
OP27 - Low noise precision op amp. DIP-8
+ Many many more. Write here or send PM if you got what I'm looking for!

I was looking at this box since I have a few CHR-70v3s in addition to attempting to designing my first TQWT for another driver. I wanted to see how Hornresp would model the results of the DDVP-10-ML. I wanted a proven design to give me a baseline to better understand Hornresp so I can model my own ideas. Perhaps my numbers are off but the graphs do not show this box/driver combination to be a good match. Would anyone else be willing to take a stab at it and see how your results compare or offer a "sample" of a well-designed TQWT in Hornresp for the CHR-70v3 that I can use as a template? I listened to several "air recordings" available on Youtube like this and this and it sounded pretty good assuming it was well recorded and my B&W headphones were not failing me which was confusing compared to my modeled response. I don't have endless time and money to indefinitely try things so I am leaning on the modeling software to help- like everyone else! QW designs, Full Range systems, and Hornresp are all new to me, so thanks!

Hi there,

I want to pick up the I2S signal from the attached circuit.
Can some help?

Many thanks!

Hi All,

I have a very odd issue and I know this is the best place to ask, hopefully I'm not alone!

3-4 times a year I start getting woofer "ringing" on one of my woofers, a "warbling" distortion in male vocals, it's been happening for years on (I think) all four Seas 5" woofers, gently pressing all of the way around the woofers rubber surround (with white gloves on) fixes it till next time.

Anyone seen this, could it be aging rubber, a stiffness, maybe its drying out (the speakers are 13 years old), any thoughts on "lubing" the rubber, I'm in Sydney and the room can get very hot in the height of summer, like around 35°C (if we are out)?

Thanks for looking.

Cheers
Richard

It now seems that without a dedicated Indie Music thread diyAudio members could be running afoul of the Genre Police often. It is hoped that this thread can minimise GP encounters. Shall we begin? ...
Wye Oak Its Way With Me (2022) ...
Login to view embedded media

hi all
i just found some pics of this amazing speaker on the net M1
first impression is WOW its big
i wonder how it sounds

i,ve been looking for ages for a design like this to use as a base for my next diy speakers but how would a 12" driver go producing midrange ?

and what about a compression driver for highs ,i know they use them alot in the pro industry but are they good enough for home audiophiles

any way i reckon they look grouse and would proberbly blow your socks off

any oppinions ?

regards sheafer

So I’ve decided to go the OB/Fullrange DIY option over the Maggies with OB subs….I guess I just appreciate a challenge!

My initial thoughts are two 15” SBAudience OB woofers for each channel…..one downfiring into SLOB type slot and the other forward facing on a 20” wide U baffle. Above would be a fullrange driver within the 6-8” class.….something that will handoff nicely to a 15” woofer in the 250-300hz range and extend to 10k…….i‘m 55 and there’s not much I can hear above 10 anyways.

My thinking here is the slot loaded woofer will extend the bottom end a little deeper. Was also considering using it in a .5 configuration and a low pass around 100hz but not sure the extra component or effort is needed since it’s going to be mechanically HF attenuated firing downward and into a slot. Thoughts?

I have for sale the following AC plugs, all are new, unused, without box.
I had a plan to use them year ago when I had US power conditioner, but eventually never used them.

szt = pcs

4 szt Wattgate 330i Audio Grade Gold
2 szt IEGO TI2020 GOLD
2 szt Wattgate 5266i
1 szt FURUTECH FI-11M

350usd shipped worldwide and paypal fee included,

I picked up three consoles on the weekend because the person wanted them out of the house to get ready to sell.
A westinghouse ra-509 "belvedere" and a westinghouse 823 and the last console had no name, It was quite old.
So in the Belvedere cabinet were the two pieces pictured below, along with the ra-509 tuner. It appears these were added to this unit.
The amp has no name but has some Canadian Hammond iron. The power tubes in push pull are 6a5g's and there is a 6sn7 and a few other tubes as you can see. The power transformer made by merit and is 800vct 200ma. The output is a Hammond 1715 PP 5k Can anyone ID this amp?

hi, that are these capacitors? What type and value?

Which type of the two is better in performance?

Hi all! I came across a Soviet Reverb Unit which is the LM-1229. Does anyone have schematics for this module by any chance?

I have aquired a jt-16a transformer and a pair of 990 opamps. I would like to build this preamp. I am looking for suggestions, tips on completing it.
Thanks

I’m having an issue with getting specific rating for capacitor replacement on an amp power board, it’s an 120vac amplifier (none car) but it’s a general question that could use the same logic I believe.
the originals are 6800uf 80v and they are 8units in the power circuit, they are arranged series parallel where both amp module is tapped on a shared power delivery (not independent arranged banks like dual power supply) just one big bank serving both audio modules.
my question is can 10000uf 80v caps be used to replaced them? Will it have too much capacitance or will it affects ESR?
Let me know if the higher values have any negative adverse issues if I used them.

Hello forum members, I took the time to write an introduction but it disappeared when I went to a different window on my phone. Briefly, I’ve been a member on diyma for around a decade and have pretty much come to endgame with my car stereo. It’s all raw drivers except the Audiofrog GS25’s as midrange. Lpg26na tweeters, Epique 7” as midbass and two ultimax IB through the cargo area floor, Minidsp 8x12.

To the point, I’ve turned my attention to building a mini receiver and bookshelves. The bookshelves are pre made .52cf enclosures with the tectonic bmr 2”, Anarchy 704’s and 8” Dayton Reference passive radiators. The receiver is a 3x7x8 electronics enclosure. The guts are a 24v 9a power supply board, Dayton kabd 2x50 and 4x30, Parts Express preamplifier board and little odds and ends.

I don’t need a preamp as the kabd boards are basically turn key solutions but it’s for the sake of art that I want a classy looking display. The preamp I’m about to use has a lesser Bluetooth, won’t control power to the amplifier boards and just looks cheesy to me. The problem is, I’m becoming more and more convinced that most diy preamp displays look cheesy and or have silly writing on them. The other one I would consider on PE has “music world” on the display most or all the time I think. I looked on the Google and eBay but not much seemed worthwhile. eBay has some interesting looking stuff but a in depth description is nearly nonexistent.

What I’m hoping to find is something that has a relay to control power to the amplifier boards, FM radio and something comparable to the aptx Bluetooth that the amps have, remote would be cool if possible. If I’m not already asking too much, none of those features matter unless the display looks high end-ish. I’m planning on fitting a nice finished 1/4” oak board as the face, possibly stained with something complementary.

I did a search before posting this but I didn’t pull up much unless I wasn’t looking in the right sub forum. I’ve been able to find everything else on my own but I’m stumped on this. I don’t have the skillset to diy a board from scratch. If an established member builds something like I’m talking about I’d consider going that route. Thanks for reading 🍻

AMP PURCHASED!

Just Like the title says I would like to buy a Whammy and/ or M^3 headphone amplifier.

Build quality is most important. For the M^3, I am fine with additions like a pot gain control, bass boost, fancy chassis etc....

The Whammy builds I have seen are mostly stock which is fine too.

I prefer the OP 627 or 4627-1 op amps and will pay extra to have them installed.

You can contact me here by private message .... or at Head-fi / sacd lover by private message.

I have posted a WTB ad on Head-fi as well.

Hi,

I just did a recap of Musical fidelity A1, my one is the very early version of A1 I think.
Here is a list of components changed in the pdf attached below. Hope it helps anyone want to do something similar.

Anyone interested in an Othorn tapped horn subwoofer? It was cut on a CNC and glued together with PL premium. It's a beast and I am sad to let it go but I just don't have room for it anymore. I'm in Los Angeles and it's a direct pickup only. $1200 for cabinet and B&C 21SW152-4 woofer. That pretty much covers cost of materials. It is made out of BB ply and has not been painted or finished in any way. It was used sparingly in my own house.

Hello everybody,

I have an older 4 channel car amp, 60w rms per channel @4ohms, 100w @2ohms, 2x200w @4ohm bridged.
Every channel is powered with Sanken 8A 2sa1694 and 2sc4467 transitor pair, rail voltage is 24v @ 12v input.

I would like to upgrade output transistors to a 15A 2sa1294 and 2sc3263 pair to achieve 80-90w rms per channel.
I have 4ohm 125w rms speakers so I would not connect any 2ohm speakers nor use channel bridging as that would most likely kill power mosfets (4x DFP50N06) or rectifiers.

Is this doable, should I choose other transistor pair, what else should I consider replacing, drivers, base resistors?

I am looking to build up some Full Range, Single Driver, Speakers. I have been wanting to get a second pair of speakers to offer something different from my '77 La Scala's. I have made some changes to the La Scala's that have resulted in excellent sound... Upgraded Tweeters, ALK crossovers, etc. Very happy with them but have longed for a more relaxed set of speakers that offer beautiful midrange detail, softer highs for mainly classical and acoustic recordings. Would like a natural and musical bass section, doesn't have to dig too deep. Single speakers set ups just seems to fit the bill... if done right.

After looking at many discussions on DIYA and others, I am very unsure of where to start... with the driver, or with the enclosure? I have looked at drivers and I've looked at enclosures... but I haven't seen exactly what I would like to do. I was hoping to get some plans for a larger driver, like 10" or 12". But I am not finding much in the way of plans for these sized drivers. So maybe that is because anything larger than 8" perhaps isn't well suited for this type of speaker design? I have a pair of Altec 417H drivers that are sitting around doing nothing... They are an instrument driver, not hifi, but they sound excellent in a Fender Twin!

I have done some basic calculations with some online calculators for a Bass Reflex enclosure. but I would like to hear from you all if I am starting out all wrong with the wrong driver. I have looked into some 8" drivers from Fostex, Seas and Mark Audio, but zero experience with these brands to even know what the house sound might offer. Also, all the plans available seem to be small bookshelf boxes. Is there a plan for a larger box and wider baffle for an 8" driver? I have the room, but would like to keep the footprint equal to or less than my La Scala's.

Totally fresh to this topic so all information is welcome.

Hello. I have a pair of 15-inch drivers and two closed cabinets of 113 litres. I was wondering if that driver could fit in that box and if anyone here could be so helpful as to give me measurements of a possible bass port. The thiele data is on the attached picture. Thanks.

Hi,

I've recently restored a Perreaux 2150B and am now looking at my SM2 class A pre-amp...

The SM2 has a few "issues" and I'm looking for any service information that anyone might have. I have already emailed Perreaux.

Any info much appreciated...

Thanks

I would like to do some work on my Audiosource AMP TWO (or the ONE, kind of the same amp)
however it looks like Audiosource is one of the hardest companies to get a service manual from
I googled and found a schematic for another one of their amps which is of absolutely no use to me, totally different amp type
I have emailed them but still have gotten no reply

has anyone here had success getting service info on Audiosource products ? what is the secret?

I will try calling soon but want to hear from others before going that route as there might be a particular person I should contact for best results.


I am aware of an extensive thread for the amp 100 but they are not similar products

Hi guys.

I know, the rule of thumb is to avoid Alitard when it comes to obsolete transistors ! But ! The picture on sellers site is showing NOS NEC 2SC3840/2SA1486. Well, you know the typical transistors from that period, plastic black/green TO-126 case with silverish painted markings on a
rough/mat surface. Something like this -->



But what I received is this -->


As you can see. Markings are made with a laser on a shiny surface. The NEC logo on 2SA1486 is missing ! Mind boggling situation. The back plate is a typical NEC transistor shape. You probably already know that Renesas took over NEC business back in 2010 and they continued to manufacture 2SC3840/2SA1486 for some time. You can even still buy them at Digikey but the minimum order is 345 pieces. Does anyone have a picture of these transistors made by Renesas btw ? I also did some hfe and Vceo (breakdown voltage) tests -->

2SA1486
Vceo - 730VDC
hfe - 60
hfe category - L

2SC3840
Vceo - 720VDC
hfe - 90
hfe category - K

So, according to NEC datasheets, these values are in the specified range. So guys, would you be so kind and share with me you opinions. Cheers.

N/a

Been through a number of iterations on developing a power amp for my stereo rig - most recently, a few months back I had a thread for a stereo SE amp built around the 807. I got as far as a crude prototype, but life intervened again. In the meantime, I found an eBay auction for an inexpensive pair of Hammond AO-39 chasses. These were reverb amps for the A100 organ, and have a 5U4-based power supply, two 6BQ5s in cathode-biased AB1, and a 12AX7. Hmmmmmm ... a pair of PP monoblocks with a little more power ... Hell yeah, I'm in!

The original circuit is built around a differential input, and is not really appropriate for a guitar power amp in a number of ways, so I designed a circuit with a Fender-esque LTP on the input and adjustable cathode bias for the power tubes. I chose to use the 6P14P-EV in order to run higher voltages (and dissipation, but as we'll see that wasn't an issue), and the 6N2P on the front end because I have a pile of them and I'd rather use my vintage ones in something where they'll make a difference.

I've successfully built the prototype, and am now stripping the chasses to prep for cleaning and painting. I may or may not reuse the noval sockets, depending on how easily they clean up (and whether I break them in the process).

Power Supply

The original power supply ran the rectifier into a dropping resistor and then to a CRC pi filter, taking the B+ from the second filter cap. This is overly complicated for my use case, so I simplified it to taking the B+ from the first filter cap. Removing 250R and using modern wall voltage raised B+ by 55V, to 370V, well within spec for these tubes. I chose 335V for the screen supply based on simulation results, and the the PI is fed a solid 300V. The 6.3V heaters will be elevated from the power tube cathodes. The 5U4 is running well within spec.



Phase Inverter

The PI is a standard Fender LTP. I think I cribbed the values from the Deluxe Reverb? Simulation showed that the 82/100 plate resistors were overcorrecting for the imbalance, so I changed to 91/100 and got very close. I think I also changed up the GNFB values.

There will be a 100k attenuator prior to the blocking cap.

Power Section

Bog-standard shared cathode bias EL84 power section. The only complication I added is a 2W 200R pot so that I can dial in the bias more closely when I change tubes. The pot goes to a 100R resistor to ground for bias measurement. I also added a 100K resistor around the pot for insurance - if the pot ever fails short, this will cut the tubes off instead of letting the bias get too hot. 470R screen resistors simulated the best balance between output and distortion. Oh, and I also built the simulation with a 16R load on an 8R transformer, because the Hammond OT wants a 4R load and I'll be using 8R cabs.



The only disappointment I've got is that due to the GNFB, it's got pretty low sensitivity. I may use a pot for it to be able to adjust sensitivity on the fly. OTOH, I'm also using a preamp that can easily drive the low sensitivity if necessary.

Specs:
5.4Vpp (1.9 Vrms, +8dbu) input yields 11W at 1% THD
7.6Vpp (2.7Vrms, +10.8dbu) input yields 14W at 5% THD (just getting into crossover distortion)
Frequency response +/- 1dB from 40Hz to 33kHz (limited by OT - the circuit simulates at +/- 0.5dB from 10Hz to 77kHz)
Output impedance ~1R in the audio range
Plate dissipation at idle: 12W
Screen dissipation at max output (14W/5%THD): 2W

I'll be posting pictures as I go to show how things are progressing. Would love to hear any thoughts on the circuit or the approach!

Hello
I have a Quad 405-2 with one channel down. One channel works but the other gives a loud mains hum. It is taking about 300 watts from the mains so I am keeping it off.
Does anyone have experience of what are the common faults on the 405-2. I have circuit diagrams and test gear like multimeter oscilloscope and signal generator and have repaired the preamp a few times now.
Help would be appreciated with common faults that give loud mains hum on one channel.

Hi,

Here is the item i would like to sell :

- 4 WAVECORE WF182BD10 SOLD

One pair for 200€ but prefer to sell the 4 in on time if its possible.


https://zupimages.net/up/21/48/bi63.jpg

https://zupimages.net/up/21/48/3n4h.jpg


- 2 HYPEX PSC2.400 SOLD

400€ excluding shipping.

- 1 HYPEX PSC2.400D SOLD

200€v excluding shipping.


https://zupimages.net/up/21/48/eoxs.jpg

- 3 Sb Acoutics TW29RN-B SOLD
One item for 100€ but prefer to sell the 3 in on time if its possible.

https://www.zupimages.net/up/21/48/vhmk.jpg

- 2 Faital 6RS140 SOLD
Pair for 170€

https://www.zupimages.net/up/21/48/an7s.jpg

https://www.zupimages.net/up/21/48/csyl.jpg

Please feel free to ask anything about my stuff.
I am in France, can ship worldwide if needed.

Best Regards