Folks:

I am soliciting interest in a small diamond buffer pcb in the Analog Line Level forum (see https://www.diyaudio.com/forums/analog-line-level/371910-rjm-audio-board-buffer-v1-1-a.html). If there is adequate demand, I will host a group buy.

Regards,
Scott

Hi guys!
I already know my question is very strange, but being a newbie, I've this curiosity.
If I have a 12 watt power amplifier (at 4 ohm) and a little cone Peerser tweeter (MT-25 HFC/4 ohm) with a 10uF capacitor connected to it, approximately how many watt I'm leading to the tweeter in question?😕
Sorry again for this stupid question.🙁
Thank you in advance for your patience
Best Regards.

Hi Guys!!!😱
I'd like to upgrade this amp circuit board! (This is one of the two amp modules!)
The pink Facon capacitor you can see and the other smaller black capacitor, are both 220 uF...the pink Facon has 50 V, whilst the black one has 16 V.
I want to replace them with two bigger capacitors (for example with two 470uF) but I've a dubt (I'm a newbie, so please forgive me if Im wrong!😕)
The Power supply unit has a stabilized current circuit (you see it in the picture)...so could this capacitors up-grade is a problem for the amplifier?😕
Thank you!
Regards😉

Hi guys!
I would to recapping this old recapping stabilized current power supply from a vintage amplifier.
As you can see in the picture, there are three pink electrolitycs capacitors: the smallest ones are 3300uF 25 V, whilst the biggest one is 6000uF 32V.
I would to replace them with three capacitors with a bigger capacitance...but I repeat, it's a stabilizer current power supply board.
As I always say here, I'm just a newbie...so my question is: is this capacitors up-grade possible or could it a problem in a similar stabilizer current circuit board?
Thank you for your patience and kindness
Regards!

Hi amigos,

I wonder if someone has already tested this HYY-01 class D amplifier, double Mono board.

This is a 2X250W class D amplifier based on IRS2092 / IRFB4227.
I read some really good opinions on the web about it but I would like to know a bit more.

- what about speakers protection ? Anti Pop @ startup ?
- what is it worth compared to the TPA3255 ?
etc

Maybe someone can help with these pictures :

this inductor is removed from the car amplifier. The consumables you see are worth 150uh .. But I could not find the code of the kernel. I want to learn to order. Some are brown and some are brown-white. How can we find out what happened?

I want to make a 2.1 system for my computer. As an amplifier I am looking at the TPA3116D2 and the lepai lp-168ha and lp-833. I know that they are all cheap Chinese stuff but I am not ready to invest into a 150 euro Dayton audio amp or a subwoofer plate amp yet.

Hi there, a few days ago I made this project and it seems not bad to me, so I did some analysis with MicroCAP.
Please tell me your oppinion (and sorry for my poor English) 🙂

28 pcs 680uf 550VDC F&T electrolytic capacitors

Happy to split, but even happier not too.

All brand spanking new, from group buy years ago.

$8USD a pc, not including shipping or fees.

Will ship anywhere, from Sydney.








8 pcs x JJ 500/500V Aluminium Electrolytic capacitors
$10 a pc excluding shipping and fees.
Will ship from Sydney anywhere.



500µF
500 VDC
88mm height
35mm diameter
Operating Temperature -25°C +70°C
Solder lug terminals
1000 Hours load life based on rated voltage and AC current load

https://www.evatco.com.au/assets/brochures/c500-500jj_.pdf

FS. PECANPI DAC WITH ITS POWER SUPPLY AND POTENTIOMETER.ONE MONTH OLD.CHANGE OF DIRECTION. £200(SAVING OF OVER£100).

The title says it all:

For the sake of tidiness, low noise etc, I would love to have a PSU that can power my RPI+DAC (5V at least 3A, less than that does not work in my hands) and my desktop amp (19 – 24 V, at least 3A) simultaneously. Does such a thing exist? Unfortunately the SilentSwitcher provides way too low current for my needs, but I love the concept!

- DIY or commercial. If DIY, something a newbie can build.

- Feed from mains or another PSU

- If it could work from a battery, extra points, but not necessary

Thank you and sorry if this is too obvious or too stupid

I just finished my first Elekit 8200 and first tube amp complete build. I'm doing a Tubelab SSE, but cannot finish it as I'm waiting for the power transformers and output transformers.

This kit is fantastic. I upgraded many capacitors and resistors (Takman). I also put in a great Alps volume pot. I'm listening to some Bill Evans right now, cooking in the system and breaking in a pair of brand new Wharfedale Denton 80th Anniversary loudspeakers. The amp and the speakers are going to be a Christmas gift for my father.

I am going to custom paint the chassis tonight so it's not bolted together. Beware of shock!

I can't believe how good this sounds. When I moved it into my tiny sunporch office to break it in and test it, I was floored. It was previously in my main living room. In the 12 x 7 sunporch, it sounds as good as my Primaluna Dialogue HP Premium integrated.

I think it may sound better with EL34s than KT88s but not sure. I have a nice stock of NOS 12AU7s to play with.

I'll post pics after the paint job is done and it's properly sealed up.

Viktor, you are the man. I wish that I could make something similar with more power to put in my main room. The lushness here is feeling more cozy and warm than my main system--which costs thousands upon thousands.

This was a great project and my dad will love it. THANK YOU VIKTOR!

Hi Guys

I mistakenly started this thread on Digital Line forum... oops, now I am in the right place. 🙂

Subject: Upgrading new Oppo Players, BDP-93 & BDP-95

Here in Australia there has been a bit of drama and delays to getting the new Oppos from the importer due to multi-region hacks causing freezing problems and nobody down here wanted them until fixed.

Many of the commercial "modders" in the US are already doing the players up. Just wondering if anybody on diyaudio has gotten their hands on '93 or '95 and done anything to them.

As far as I can tell it is a 27MHz(?) Master Clock on the main MediaTek chip.

On the stereo analog outputs, transformers with 1:1 ratio can be used on both the CS4382 DAC on the '93 and also on the Sabre DAC on the '95

I believe both these players are going to be SIGNIFICANT for most, if not all, of us !!!

This really excites me!

Players and DACs that can play non-compressed or lossless full resolution files... this is the FUTURE!

They play FLAC files, even Hi-Rez to full MCH, Wave files too. I have a bunch of 24 bit FLAC files, music that I have downloaded legally from B&W (yes, the speaker people), including the latest Peter Gabriel "Scratch My Back" album.

Actually not fussed about the video side, but believe it will be very good as Oppo usually is, but we are of course DIY Audio guys.

Over to you and comments you may have.

Cheers, Joe R.

Hi,

if you ever bump into one set of these and you feel like they play a little cautious, remember this measurement may help you understand why. Screenshot represents an on-axis measurement of one original loudspeaker. Measurement is valid approx. from 100Hz and up.

Midwoofer: Focal 5V3251
Tweeter: Focal TNC

Hi,

For speaker crossover design requirement is DCR matching mandatory (zaphaudio SB12.3)
4 mH DCR - 0.21

Locally I have found 4.0 mH / 16 AWG but DCR is 0.282 Ohm

Does 0.21 vs 0.282 makes any difference. Can I go with 0.282 Ohm without having any impact to design/sound.

Thank you

Here's a question for the EMI/HF people out there:

If I have a balanced line input stage like shown in the schematic below - do I want to have "CX" in there or not?

Bruno Putzeys makes a strong point for high common mode input impedance in his article "The G-Word" (https://www.diyaudio.com/archive/bl...d1460406090-bruno-putzeys-micropre-g-word.pdf , page 7). My question is:

Is that true also for the MHz range and above, where the CMRR of the input opamps will degrade, when frequencies start to rise? Wouldn't it be better if HF junk including common mode HF stuff is tied to the ground plane nearest to the input jack's ground pin, which in turn is connected to the chassis? That way those HF currents would have very short loops inside the case.

This amplifier sound quite flat and it is now under my modification.
I will post more info later.

http://i20.photobucket.com/albums/b206/etsang3/Krell/KST-100/krell_kst100.jpg

I love custom made elements on my enclosures and I also love to reuse or hide memorable used objects in my creations that would otherwise just collect dust. Recently I recycled some wood from the old garden chairs from my parents house. The chairs were old, unusable and certainly not "en vogue". But they were the chairs I spent a lot of happy childhood moments on and I am glad to have found a way to preserve these memories by reusing some of their wood in a project and not having to keep the chairs themselves.

I find poti and fader knobs are a great way to give DIY-creations a very personal touch and to "hide" such memorable gimmicks that tell a story. They are often in plain sight and even touched frequently. Reason enough to give those elements some thought in my opinion.

With this little report I want to share how I managed to use almost every object as a poti or fader knob. In fact anything that can be drilled and glued will work. I'm covering only potis with a rippled shaft thoug, as I found them to be most problematic. Knobs for these potis (and faders) work simply by friction and I didn't quite succeed at drilling holes with just the perfect fit (loose enough to be taken on and off while still tight enough to be safely turned). Not all materials would even be suitable for that perfect "friction fit" - wood will wear out while metal is too smooth.

What I came up with is to 3D-print sort of inlays that feature the same ripple pattern as the poti shafts and can be glued into easy to drill holes (say 8mm). The 3D-printed material (PETG in my case) provides good fricition and some flexibility at the same time to allow for a perfect fit. The plastic is not visible from the outside and only serves as an adapter between shaft and knob.

I glue those 3D-printed inlays with 2K epoxy glue into the knobs, which will keep them in place forever and works on almost every material.



Here's another example for fader knobs made from oak with a brass inlay:

For sale, two pairs of speakers built this calendar year. All new components from PE.
1. Inspired by the Philharmonitor BMR, a pair of active speakers with Hivi RT1.3 tweeter, BMR mid and Dayton RS180p-4 woofer. A pair of Minidsp 2x4 for crossover and eq included. Cabinets are 3/4” mdf with red oak baffles. The finish on the mdf needs sanding and repainting. The mid driver is in its own sealed enclosure similar to the Phil, stuffed with eco core insulation. Fiber glass lining in the main cabinet. Baffles are detachable. I am so impressed with these that I plan on building the real version.
Speakers and two minidsp. $400 plus shipping from 28901. NOT FOR SALE ANYMORE.

2. LXmini clones with Peerless TC9 and Dayton RS150-4. Woodwork is red maple.
Speakers $150 plus shipping. SOLD. Thank you, Ray

All components brand new this year and perfect order.
Thanks
Peter

Greetings,

I've gotten the itch to start playing with some loudspeakers again...

I know I really love the sound of Quested's 2-ways with the Volt woofers. I use a pair of Q108s on a regular basis and really like them. I'm thinking of building a 2-way using Quested's design as a starting point.

The two 8" drivers in contention are the B228.8 and the B220.2. From what I can tell, the B228.8 is probably a better choice for a 2-way.

As far as I know, the 8" Volt driver in the H108 / V2108 is a custom driver, and I'm sure Volt won't sell them to anyone other than Quested. On the woofer in the Q108, the number is B220.7. This is obviously different from the B228.8 (which I understand is similar or the same as the B220.8)- it's clearly a different cone material. Out of curiosity, does anyone know how similar / different the B228.8 is to the driver that Quested uses?

Besides the Morel MDT30, are there any tweeters I should be considering? I'm thinking of crossing somewhere in the 1.5 kHz - 2 kHz range, so something with decent bottom end is definitely important.

Lastly, how do the Volt woofers compare to the 7" Scan-Speak Relevators? The Volt drivers in the Quested feel very "fast", for lack of a better word. They handle dynamics really well. How are the Scan-Speaks in this regard?

Heya.

This is my recent project, a pair of Jeff Bagby's "The Tributes" speakers. For anyone wondering, they sound bloody amazing and imaging is just perfect. The final cost was just slightly under 300 euros and I have built them at my uncle's workshop during last school holidays.

I am bad at attaching files so there is just imgur album link. Jegg Bagby's Tributes Build - Album on Imgur

Hello fellow enthusiasts,

Im building a pair of 2way speakers for my garden and Im planning to use TXD-252 crossover that I bought online second-hand.

In the manual its is written:

• Passive: 12dB/octave high-pass and low-pass at 1kHz
• Active: 24dB/octave Linkwitz-Riley @ 1kHz

Please have a look at the pictures and help me identify how should I connect to get the "24dB/octave Linkwitz-Riley @ 1kHz". And what is this connection "X?" on the board?

Thanks
Rando

I bought 20 pairs of 2SC5171 / 2SA1930 this week from kessler-electronic de. The 2SC1930 pieces I received is on the picture. Only two pieces of 2SA1930 have Toshiba marked logo. The other pieces of 2SA1930 & 2SC5171 are like the one on the right of the picture.

I would like to ask if there is a chance that the non-Toshiba-logo pieces of 2SA1930/2SC5171 I bought are legit?

I have a pet peeve - inadequate documentation.
In addition to fixing gear for the majority of my life I've also been designing stuff as a career. I am diligent about documentation. There's nothing that gets my goat more than "inadequate documentation".
Considering the drafting of a schematic, you wont' catch me:
1. not labeling pin numbers
2. leaving out reference designators (Fender is guilty - how many instances of 100k resistors are to be found on a point to point layout for example).
3. not labeling parts with a manufacturere's part number.
4. etc...******* etc...
I am fed up!

Attention manufactures!
If someone wants me to fix something that you don't provide adequate documentation for I will log onto Facebook and spew **** about your company.

Hello guys, my question is pretty simple.
What is the best sounding pentode SE amplifier that you have heard?
Can it be so good when built nice that it can compete with SET amps?
Best regards. Michal

Hello, please show me the formula for calculating the envelope for the hyperexponential horn shape.

I am new to the crossover realm and was wondering how I would achieve running

Tang band 6.5 “ 50 watt rms , 4 ohm, 35-800hz
Dayton 4” 30 watt rms, 4 ohm, 80-20,000 hz
Hivi 1” dome tweeter 16 watt rms, 2,500-20,000 hz

I got this design off the web and was supposed to be running a lepai plate amp on back but they sound like garbage . So I figured I would try out some cross overs and run them directly to my Av

Anyone make a lighted subwoofer out of himilayan salt bricks?

I picked up this amp locally for a song. Didn't even care if it had problems cheap. Only testing was to verify power up without blowing fuses and that bridged it made ok noise.

Tried rigging it in a vehicle and it shows the symptom: 3 channels ok, left front channel has reduced and hashy output. Not dead, trying to pass signal, but no bueno.

Does anyone have any service literature on this model? I googled for awhile and couldn't find a print for this one. I also read that rockford fosgate uses the same architecture across multiple units. This one says pc-4343b by the toroid, if that helps.

Also it seems that previous owner(s) stripped out just about all of the set screws in the speaker terminals. Looking for ideas on what fits or where to source parts. Given a hard choice, I'd rather drill and tap the existing bars out and use larger set screws, rather than wiring up pigtails or some other kludge.

I have plenty of experience in electronic repair. Amateur radio in highschool: earned my technician class license. Enlisted in the navy as an avionics tech. Went aircrew after about a year, qualified for an encyclopedia of stuff. Now I'm a welder fabricator.

Hi,

I bot TPA3255 "dual core" amplifier from AliExpress.
It works but decided to made upgrade.
LC filter inductors replaced to Coilcraft SER2918H-103KL and capacitors to WIMA 0.47uFx250V.
Supply voltage 41V from linear PSU.

After upgrade, switched on. No load.
After ~20sec ceramics capacitors off slave channel PVDD started to explode.

1uFx100V X7R capacitors has been added on PSU plus line and electrolytic as well.
Then 1uF capacitors has been exploded with fire in slave channel when switched on.
Master channel don't explode capacitors at all.

Then twisted wires connected to output terminals, slave channel PVDD ceramics capacitors starting to show fireworks faster.
DC voltage has been tested on TPA3255 inputs before mods. One IC had 3.5V, second 3.9V.

Could get advise that need to do to make slave channel working ?

Speaker lobing calculator - Polar response | Audio Judgement

Scroll down to MTM- it says specifically main drivers need to be 1 wavelength apart
Is this a classic d'appolito description?

I've just completed a couple preamp boards by Greg Ball - called the SKA Pre. Each channel is on a separate board. One board works fine. The other seems to be oscillating at about 14MHz but only with the input shorted. In other words, with the volume potentiometer turned for minimum (i.e. input connected to ground) the oscillation is at its maximum. As the volume potentiometer is turned up, the oscillation disappears. Attached is the schematic. Any suggestions will be appreciated.

I think I remember, from back in the days before powered subs, that there was a way to connect a single passive sub to a standard stereo amplifier that was also driving the main speakers. There may have been some other misc capacitors or something involved, but it was an extremely simple thing, that worked to combine both L+R signals for the subwoofer, but keeping L and R separate to each of the main speakers.

I can’t seem to remember, or to find, that method anywhere. Of course there’d be very little application for it today, except in the mind of some old 60+ experimenter who has this thing that he wants to connect to that thing, and can’t remember how to do it. 🙂

Assume that this thing will have a simple lowpass filter... any ideas?

Sold

I tore the original CMOS opamp off of a FreeDSP Classic and ran it passive output filter. I think it sounded better before I did that, so I want to replace the active filter. Problem is the only thing I have on hand is a OPA1644. I was wondering if anyone knew what would happen with an amp rated down to 4.5 volts being fed with only 3.3. I figure anything could happen, mostly bad, but that someone might know..

OK, so I hope that life is settling in enough for me to actually try a simple project. So I was thinking of a simple preamp using parts bin bits which includes lots of 12AX7s and 12AU7s. The basic idea is a 12AX7 gain stage direct coupled to a 12AU7 follower with FB from the follower output to the input. Gain is set a bit on the high side intentionally since my power amp is pretty low sensitivity.

Of course my natural tendency is toward mission creep so I thought why not add a simple contour control to the FB loop since that is probably all the EQ I would typically need. R9, R10, C4, and L1 make up the contour control. With no L making a mid/high shelf is no problem but adding the L naturally results in some interactions that cause a big bump around 25k-100kHz at least in the simulation.

Besides the extra very high frequency response my concern is stability. So my first thought was to add a cap (comp cap on the schematic) to roll off response over 30kHz.

So the question is this type of contour control a bad idea over all and if not what would be the best way to stabalize and control HF response?

on this volume board:

Balanced in/out 256 steps volume control board passive pre-amplifier stereo



the pot need to be linear, i'm using a an alp stereo log pot and it trip the relays easily

i'm having a hard time to find a 2 gang pot linear that fit size wize like an alp pot?

(i do not need to balanced my signal)

thanks

Martin

Im looking at building this phono stage here and it specifies an oddball capacitor value of 0.0295uf (29500pf)


Ive found a source for a NOS cap but is only rated at 100v/2% and the schematic specifies 400V 1% tolerance, however i did some calculations and the voltage between R5 and R6 is only about 22V, so I should be OK with one rated at only 100V?

I have some K1530/J201 I bought long time ago (supposedly matched but not sure how well). I also have some K2013/J313 as well as some papa's j favorites 170/74. I have been mulling putting all of these to a good use.

While sort of keeping an eye on what amp could use these I seem to have missed a nice pointer from Papa himself that the front end of the Sony VFET 2 could drive these nicely.

Please check out the Vfet front end schematic and Papa's comments. I am far from an expert: it sounds to me the FE could be used to drive something like an F4 output stage? just drop the buffer. Did I get that wrong?

Could maybe someone draw up or sim what this should look like with say 2 (or 3) pairs of K1530/J201 per channel and which values would need adjustment? maybe estimate a few starting values if the rails were at +/-28V shared with the FE? Thanks a lot. Your help is much appreciated.





also please feel free to post in this thread other amps which make use of the Toshiba parts.

p.s. I am also hoping Papa gets bored one afternoon (probably no chance with everything else going on right now but eventually), and finishes his thought with a nice schematic; sort of "a tribute to Toshiba" even though the parts are conventional in comparison to Sony prima donnas 😉.

This thread is about designing a vacuum tube front end for the Sony VFET DIY amp. There are already a number of sand based front ends, but I thought a vacuum option would be nice, too!

Design targets:

• Should be relatively easy to build so the average DIY VFET builder can cope with it.
• Should fit in the DIY VFET chassis. If possible, the chassis should not need any modifications (like drilling more holes).
• Avoid dangerously high voltages -- this is for rookies!
• The front end needs to provide high input impedance and low output impedance to drive the VFET/SIT output stage.
• Single ended input signals with up to ±2 Vpeak (4 V peak-to-peak).
• Voltage gain of approximately 7-8.
• Should not impose its own distortion over the distortion profile of the VFET output stage (except maybe if the harmonics of the front end are opposite phase than those of the VFET output, resulting in cancellation of harmonics).
• Must avoid any possibility to zap the VFET in the output stage, even in case of a (high-voltage) failure. The VFETs are almost unobtanium!

(This post is a followup to the discussion that started in the "Scourge, Bulwark, Marauder, Dreadnought front end cards for DIY VFET amp" thread, and relevant posts from this thread will be moved here.)

Who has the F7 power amplifier circuit diagram?
thanks

Hi everybody, so I recently bought one of the new tpa3110 Bluetooth only boards that are circulating around eBay, the problem is that even though it seems a good overall amplifier, whenever you turn on the amplifier you hear a god awful Chinese lady screaming at you saying the Bluetooth device is "readi to pehr " and it made me sad because for around 5€ it's a really good ~8wrms solution for small diy speakers. I had the idea that maybe I could reprogram the Bluetooth ic and rid it of this curse but I have never seen one of these SSOP-28 ic before, mine came laser etched to hide the chip part number but I have seen the same board on eBay with the description intact and it says it a " JL" chip which I have no idea what manufacturer it refers to and the part number is AC1524E6M670-02A

Can someone shed a light on this ?

Link from Bangood because of good photo quality :

http://http://m.banggood.com/TPA3110-DC-10V-25V-2x15W-Dual-Channel-Wireless-Bluetooth-Audio-Power-Amplifier-Board-For-Speaker-p-1087006.html

What Does “Hi-Fi” Even Mean Anymore? This Is What the Experts Say

The modern definition of hi-fi is a bit ambiguous. Is it CD or vinyl quality? Or is it something even higher resolution than that?

What Does “Hi-Fi” Even Mean Anymore? This Is What the Experts Say

I apologize in advance if this question shows my inexperience, or comes across as asking for a free education without putting in the work. I'm hoping someone might be able to tell me what is going on here, or at least point me in the right direction so I can figure it out myself. Anyway...

The attached schematic is for the preamp/power amp section of my Lafayette LA-226C stereo receiver, a rebadged Trio WX-400. I recapped it and cleaned it up, and now it sounds very nice, and generally speaking I'm very happy with it. I just want to know more about how this circuit works. Only one channel is shown in the schematic, of course. The rest is mostly not pertinent.

My question stems from what's going on with the cathodes of the output tubes. As you can see, the two cathodes are tied together--the other two 6BQ5s have their cathodes tied into the same node as well. I realize that this is not a particularly unusual practice, especially for amps of this time period. I have a matched quad of JJ EL84s in it, since this means they are all biased together.

What I can't figure out for the life of me is why there are two resistors seemingly forming a voltage divider, with a 9V output going to the grids of the output tubes through those 470kOhm resistors. Is this intended to add a positive bias to the control grid? Or something else? Maybe loading the cathodyne phase inverter?

OK, if by some miracle I got that part right, now comes the really confusing part (for me, anyway). On our way down to the cathode resistors, we also see two series tube heaters in parallel with the cathode resistors. So, I assume that with the resistance of the heaters in parallel with the cathode resistors, they are also an important part of biasing the output tubes. Furthermore, I guess this means that the 150V 40uF capacitor serves both to smooth the DC for the filaments of V13 and V14, as well as a cathode bypass cap... I think??? Since it seems like the heaters of V13 and V14 are important for the output tubes' bias, I have made sure that I put healthy tubes here. More on them later.

Finally, to top it all off, maybe everything I just said is basically moot, or not, because where you see the little "K" with a circle around it leads to a little humdinger-type potentiometer (100k, linear) between the +/- of a 5V 0.3A secondary of the power transformer. So I don't know how that affects the bias, if at all. Interestingly enough, the hum balance knob doesn't do anything. The receiver is already absolutely dead silent. (woohoo!)

So how does one calculate the cathode resistance/current through the output tubes?

The reason I ask is because, in addition to my own curiosity, I may eventually like to modify this part of the circuit. It is my understanding that with the tubes biased this way, a matched quad is necessary, and if one of them goes down, the others go with it. For the sake of reliability, it might be nice to change this so each tube, or at least each p-p pair, gets its own cathode resistor (and cap, if necessary). Also, again for the sake of reliability, it would be preferable imo to have the heaters of V13 and V14 out of the circuit. In fact, I've noticed the power transformer runs pretty hot, so maybe in the long run the best move would be to pull V13 and V14 entirely. V13 and V14 comprise the RIAA preamp, which I don't ever intend to use--this receiver doesn't even have a ground screw, and I've got other, better phono preamps anyway. I should also note that I'm not concerned about the resale of the unit, so any (reasonable) mods don't bother me, and shouldn't bother you either 😉

Sorry for being so long winded. Can anybody help??

Hi,

This is my first post.

I have 2 amps that went dead recently, I have them apart, but struggling to find the problem, both amps are stuck in protect mode. Both have hi voltage across rails, so PSU's look to be ok.


Anyone have the service manuals? could you please send them to me.

Thx in advanced.

Looking for a couple of TO-3 IRF240s

Lucas

I need this dac to support coaxial input, how can I convert it?

I wanted to use it for my subwoofers, along with a mini dsp nano digi that only has coaxial outputs

DS-DAC-100 - 1BIT USB-DAC | KORG (Spain)

With VU meters and drivercard for VU.
With 44
Dept28
Hight 8 cm

35 euro plus shipping + PF

This will be my first Purifi PTT6.5 build project. The plan is to make flush mount bolts to cleanup the lines of the frame/baffle area.

I have no clue whether they matter acoustically. I just find the standard cap screw, or whatever other standard fastener, to be clunky. If there really must be a reason, chalk it up to fabrication warmup exercises.

The goal is to have one completed by this Wed. but I'll give myself a week if it takes that long.

Oh, and it coincidentally looks like something I've seen elsewhere, but I can't quite put my finger on it...

Hi all

Anybody who wants to guess the resistor value R134

Its around 1/2 inch (13 mm) long i think its flame proof (fusible)




Best regards
KO

Selling a very lightly used QA400 audio analyzer. I have a RTX so this just collects dust. Please keep in mind that this unit does not work with Windows 10. Please search forum for QA400 thread.

Asking: $99
Shipping: $10 (US Only)

Lucas

Hello,

Do rotary encoders with limited rotation travel exist? i.e. fixed travel like a pot, but digital output. Or a way to convert a pot's resistance to a digital value?

I'm planning a DSP based audio project, with user adjustable settings (gain, threshold, etc.). The DSP (ADAU1701) supports digital input via rotary encoders. Searching online it appears that all rotary encoders rotate continuously, which would require a display to show the current value (12db). I'd rather the UX react like a pot with fixed travel (say 7 o-clock CW to 5 o-clock) and silkscreen the values on the project chassis.

Any assistance would be appreciated.
Thanks!

I just heard about acoustic coupling with subwoofers and now I'm kind of confused. I'm in the process of building a pair of 3 way computer speakers, and because they are computer speakers, the woofers will be pretty close together. (Probably three to four feet?)

I know that acoustic coupling yields a 3 db boost at lower frequencies. Would I have to worry about an overboosted bass response? Would I have to eq this out? I prefer neutrality.

Just ordered the Elekit TU-8600S. I want to order the cap upgrade next, but not sure which is the correct value. I did some reading here but it seems either .1 uf or .22uf is used for the TU-8600. Is one the correct value and the other a preferred value? Looking at the V-cap ODAM capacitors, just don't know the correct value. Any help appreciated. Thanks 😀

Do the caps need to match? Some offer capacitor matching service, within 5%, 2%, 1%. Not sure if it’s needed.

Hi there,
I've got a Yamaha tyros 4 in for repair and the keys seems to have a mind of their own, some keys make sound, some comes out on full volume, some keys remains to sustain long after the key is released and some don't even make sound. Its not consistent meaning the same note does not behave the same all the time.
The keyboard had some issues in the past but it was typical velocity/dead keys and cleaning the rubber contacts solved the problem. However this time it seems this is not the case, I did clean the whole keybed nonetheless and to no surprise it didn't solve the problem. Did a factory reset and it didn't solve the problem either.
So I took out the oscilloscope and probed the scanning pins. Here is what I found:
1. All the pins marked BK (BK00-BK13) shows a nice square wave, with no noise. The 'on' time is longer than the 'off' time.
2. Pins marked with MK does not show a steady square wave but a weird 'spiky' wave - like a weird 'saw-toothish' wave. MK24 was the worst, also on one MK pin(can't remember which one) it showed a square wave superimposed over the wired sawtooth wave.

I couldn't probe around the IC as I would have to disassemble the whole keybed. Was hoping I could get your guys advice on what to look for next and what could be the probable cause for this fault.

Appreciate the help.

You can buy a brand new Swiss watch costing thousands of pounds which will be no more and quite possibly less accurate than a digital watch from the far East and costing a few tens of pounds - I spent eight years working for a major UK Jeweller 😉

You can buy a pair of late(ish) second-hand Kef T27s and Kef B110s for less than a hundred pounds.

A pair of BBC LS3/5As will cost you hundreds of pounds on the Bay.

Falcon Acoustics are now manufacturing brand new T27s (£144 a pair) and B110s (also £144 a pair) and will sell you a pair of assembled replica LS3/5As with the 15 Ohm FL6/23 crossover for £1,200! A full cabinet kit without speakers but with a crossover will set you back £311.

According to the BBC White Paper (RD1976/29), the LS3/5A cabinet measures 31 cms high by 19 cms wide by 16 cms deep and has a free volume of a little under five litres.

Aside from the obvious requirement that the speaker should accurately reproduce sound, two key BBC design requirements for the LS3/5A were that:

1. it should be as small as possible consistent with an adequate axial response / frequency characteristic in order to allow use in environments where monitoring on headphones was not satisfactory and yet there wasn't sufficient room for a 'Grade I' monitor - e.g. Outside Broadcast vans.
2. examples of it should be 100% consistent and interchangeable.

Kef's specification for the B110 suggests a totally enclosed box of five to ten litres should be used.

In a document dated July 1985 describing the construction of a replica LS3/5A, Falcon Acoustics recommended that the depth of the cabinet could usefully be increased from 16 cms to 23cms for a more extended bass.

My question is whether one can build a better sounding small speaker based on the Kef T27 and B110 and if so, what would be its characteristics? I would appreciate it if the discussion could concentrate on just these two drivers and start from the original BBC LS3/5A design. I am interested in hearing views based on the dimensions (e.g. making the cabinet twice as deep -or- twice as deep but triangular), cabinet materials (e.g. braced 25 mm MDF rather than 12 mm birch ply) and (passive) crossover design.

I can offer OEM WE300B to Elekit or Sunvalley Kit amp owner.

SOLD!
6 x SPARKOS LABS SS3602 Dual Discrete OPA DIP8

Picture
Dropbox - Sparkos.jpg - Simplify your life

More Info
Dual Discrete Op Amp SS3602 - Sparkos Labs, Inc.

Price
New: 398 EUR
Sale for: 250 EUR

Regards
Micke (Sweden)

SOLD!

Hello all,
I bought a replacement capacitor kit for the crossovers in my Kef 104/2 speakers.
I purchased the kit from Falcon Acoustics, and they matched all my old capacitors for value except for two 50u/100v caps. They did not send any 50s, however they did send two 120u/100v. I'm assuming I am supposed to use these in place of the 50u caps. For those of you familiar with these crossovers, the 50u caps are in position C10 on the schematic.
Does anyone know I could plug these in where the 50s were, or that is too much of a value change?
I would/ will take this up with Falcon, however I have read here, and elsewhere, that they are not very good with email replies.
Asking for advice here, thanks in advance.
Dan.

Hi. I purchased a asus H170I-PRO motherboard for £159, was hoping that since it was quite expensive it would have good quality components and good av performance for use as a htpc.
Turned out to be not so good, picture is okay, sound is a little flat and lifeless.
Am looking for any recommendations for motherboards with high quality audio and video cards built in, or is this even possible? What is the best bang for your buck out there.
Or should i get something external, perhaps a usb multichannel dac for the audio. Any recommendations are appreciated. Have a budget of £300, is there any giant killers that have impressed you. Would be prepared to buy second hand if it goes over the budget.
Many thanks

This has been stuck on my bench since before lockdown 1. I was hooked with the student owner saying the previous repair tech he had been to said the amp is beyond economical repair!

https://www.diyaudio.com/forums/attachment.php?attachmentid=944248&stc=1&d=1618919251

Googling W audio, Zenith 3000, prolight.co.uk (importer) got me the operator handbook no schematics so after drawing it up in Kicad, I was curious about one of the heatsink temperature sensors and Googling "90AR3U3" lead to a W_Audio_Zenith_3000_Schematic.PDF for the whole amp! (I just tried to repeat this and failed, cut and past the pdf string instead.)

https://www.diyaudio.com/forums/attachment.php?attachmentid=944249&stc=1&d=1618919251

My KiCAD drawn reverse engineered schematic is V1.0 the other found one for V1.5. To save you playing "spot the difference" they have replaced the triac crowbar with output relay and delay / DC detect circuit and gone to single emitter resistors, the rest of the amp appears to be the same.

On first look after lifting the lid, what jumps out is the absence of isolation pads between output transistors and heat sink. The heat sink is isolated from the case by a thin sheet of fibreglass and is at output potential.

The emitter current share resistors in V1.0 are paralleled pairs of 2W 0R68 and had all "silently" failed open circuit (no sooty skid marks!) is this a metal film failure characteristic?

The only evidence of explosion was a few TO92 with "plasma ejection holes" and charcoaled 1/4W resistors. Removing the PCB from heat sink revealed a few vaporised tracks.

I was hopefully expectant of success after searching and replacing all shorted transistors and diodes and open circuit resistors and missing PCB traces repaired but all to no avail. Both channels refuse to come back to life. I have "come a gutsa" and I am stuck.

Fault finding efforts so far:

With no main output the opamp is open loop so a bit giddy, (proves the clip indicator works!) I've tacked a 100K across pin 1 and 2 to get a test sine wave established between D1 and D2. Dual trace scope (see opening pic) at the e of T11 and T12 can show +ve sine half on T11 and -ve sine half on T12 but only with asymmetrical fine tuning of the power rails (bench supply I'm not poking about with a 3000VA backed PSU) and D7 anode lifted. Once set it is repeatable, turning off/on takes a few seconds for the scope trace to drift back to equilibrium. I've temporarily tacked on a LED to show Mute operating, hardly a second at power up, longer at turn off and I checked, it comes on with a heat gun on the heat sink temp sensor.

How is this deceptively simple circuit of three stacked transistors T11,T13,T15 (T12,T14,T16) per rail supposed to work? I am intrigued by T13 and T14 separating the +-150V (approx with a rail switch) from the +/- 15V small signal operating environment for the opamp to play in.

If you have any advice or fault finding suggestions to help me get this going I will be very grateful. Many thanks.
Mr Chris

Hi,
Would like to know if anyone has these lateral FET's in Europe?
So far I received fakes from 2 sites.

Thanks!

Recently I bought some of this cable, SH, cheap and without termination. Its silver coated copper in teflon, seems nice and I would like to put some banana connectors on it. Cant really try it on my main system because we escaped to country cottage after earthquake and Covid crisis didnt help. I dont need bi-wire cable so my question is how to terminate it? Can I split that in two by removing transparent coat (model name is printed on it) or just put 4 + 4 together? If anyone had that cable I would be thankful for advice.
APATURE PRODUCTS - DIGITAL VIDEO - DVD - AUDIO - HOME THEATER

After a failed attempt of a cloned Maplin 4-20 amplifier I thought I would rescue the expensive components and try this Williamson design PCB.

I won't get the schematics until the PCB arrives but it appears to use the 4 x octal sockets for the EL34 output tubes and B9A sockets for the pre-amp and phase splitter tubes.

I'm guessing these will be EF86 and ECC83.

My OPTs are Hammond 1650H.

Hi there,

I'm looking for an amplifier (possibly a complete plate amplifier) to supply about 500W @8Ohms. It needs to take rough handing and transport. This project is a subwoofer, but other projects will probably arise.

What I'd ideally like is something very reliable and reasonable sounding on a fairly low budget. Really, I don't want to spend more than £200-£250 for a fully working unit. Does such a product exist? Or can it be assembled from parts?

I've looked at brands like Dayton audio, but I happen to know their amps were used in some speakers I own, and they've gone wrong twice.

Thanks,
Peter

Starting this thread for documentation/notes etc.

Amp had blown PS fets, RFP50N06 x 12 all shorted gate to drain.
22 ohm gates, but there is also a single 1/4w 10ohm resistor before the gates from the SG per side. That resistor got a little burned up but still w/i tollerance.
Directly driven from an SG3525A

Nothing seems shorted in the output section at all.

Board seems to be triple layered.

When I first tested the amp, REM did nothing, but the amp did draw 0.5A of current with or without rem attached. I put my scope on the gates of the bad 50N06 and noticed either a PWM drive like I hadn't seen before, or the drive was very wrong looking.

I proceeded to removed all PS fets, and then installed just one IRF3205 into each bank. I may drop those to IRFZ44/48 however.

Still not getting anything out of REM, but the amp is still drawing slightly at 0.02A with or without rem. Most of the pins on the SG3525A are at zero or less than 0.5vDC. Pin15 is seeing only 0.5vDC and so its not getting much supply voltage there either. I may pull this IC especially if it shorted out, not sure yet.

U8 is an LM2903. It sits between REM and, a diode, and 1~2 resistors. Do these voltages seem to be ok?

U8 LM2903
1: 13.35
2: 13.58
3: 12.26
4: 0
5: 12.58
6: 13.35
7: 13.36
8: 14.44

The ONLY other IC in the PS seeing anything more than about 0.5vDC on any IC pins is U2, a LM2703 which has 12.26vDC only on pin 1.

Thank you

Hello diy fellows

I have several of very solid build Abbott Transistor DC converter, filter or maybe choke. I could not find any information about this special part and also did not found something with similar specs from Abbott Transistor. Would be really great if you can help me identifying what this thing exactly is.

Here are two pictures. These are shared on my google drive as I do not know how to upload pictures directly from an iPhone.

IMG_0152.jpg - Google Drive

IMG_0147.jpg - Google Drive

Kind Regards and thanks in advance

Phil

Hello community,
this is my first post. I built some speakers in the past, but never used any computer simulation to design them.
This time I designed a bass-reflex loudspeaker using Boxsim (Boxsim - Homepage) with Visaton drivers.
I have attached the frequency range that Boxsim computed. As you can see, I did a tradeoff of losing sensitivity for gaining bass response (the 10mH coil in parallel with the 2.2/1.5Ohm resistors is basically a low-shelf filter).
The frequency range, as seen on screen is +/-2dB @ 32Hz-20kHz which seems extremely good for a loudspeaker of this size - But that's all only on screen... Since I have no experience in this domain, I would like to get some approval/criticism from the loudspeaker experts in here. I don't want to build the speaker only to find out that it sucks. Therefore, please go ahead and let me know what you think of this design. All criticism welcome - but please always with rational arguments. Thanks in advance!

For reference, here are the drivers I used:
W 170 S - 4 Ohm | Visaton
G 20 SC - 8 Ohm | Visaton

Hello,

I've been studying others' solutions to setting up different bias conditions for different output tubes, without having to physically replace resistors.

To begin with I was thinking to put a 560 Ohm and 250 Ohm resistor in series to act as the cathode bias, then paralleling the 250 Ohm via a switch in order to select either 810 Ohm (560 + 250) or 560 Ohm so as to create bias conditions for EL34 and KT88 respectively. However I'm not sure this is particularly elegant due to physical space constraints with the PCB.

I notice r_knize has a six position switch that puts one of six resistors in parallel with the one on the board in order to enable bias conditions for most tubes. Nice!

This all looked a bit fiddly though, and I was considering putting in a 1000 Ohm variable resistor or potentiometer (don't really know the difference!) in order to have complete control of the bias conditions rather than be limited to discrete values.

Am I completely bonkers to consider this?

View attachment 946563


Hi and thanks for reading. I have built this amplifier, please see attached circuit diagram. It is working fine the midrange and treble are good but whenever the amplifier tries to reproduce a low bass note i get a lot of distortion.
What do you think is wrong can you please advise.

Hi,

Been looking around to build a nice sounding 5W amp, I have the ACA which I truly enjoy so this leads to for wanting more of Mr Pass design.

I bought some components to built the F5 but this will be later, a fall project. I have a whole bunch of NOS TO3 lateral mosfet that I'd like to use soon.

Looking for some recommendation, I heard that sound wise the Aleph 3 sounds like the ACA, makes sense ? I'd like to avoid building an amp that sounds extremely similar to the ACA which I already own, I'd like to taste a 'different wine' while building a Pass design.

I'm now looking into the Zen but a low power version (+24V-Gnd) to get about 5W. Any other recommendation are welcome.

My speakers are MLTL with FE206E and my music taste is mainly Blues, Jazz and Classic.

I own a few low power tube amps, all SE except for one.

LATEST INFO : Juma came up with a design, please see post no. 217.

Thanks for your time.
Eric

Hi, I couldn't drop the bias current less than 6mv over output resistor for only one channel. I've tried for weeks 🙂 When I want to adjust semipot it drop the 6mv and increase again. Min value is 6mv (about 90ma or more) over 0.067 ohm resistor (R196). The other channel can drop to 1mv or less.

I changed all elect. caps and most of transistors. (not earlier stage of amp. and not power output transistor Q139,Q141). But, all looks like ok. resistors are ok.
After weeks I want to ask here. I couldn't solve 🙂 Any idea will be very helpfull. note that there is no problem in sound! I add the schematic here;

Hi I have a 7.3.0 set up and it is currently using a Mini DSP to time align and EQ my three subs,

As I have no way of crossing over the low frequencies that go to the mains I was thinking of simply using the second input from L or R (or both ?) to input 2

I can put a roll off on the input as my subs go up to 70Hz and my fronts go down to 30Hz, So I was thinking of adding everything below 35Hz to the Mini DSP and subs

So I was thinking of taking the analogue out from the processor and 'Y' cabling to both the power amp and the Mini DSP for L, R or both

My question is can I build a cable that mixed the L,R channels and shared the earth on the RCA without corrupting channel seperation or just use, L or R ?

Hello everyone. I hope you are all doing fine. I have LEAP and LMS from LinearX co that does not exist anymore due to passing away of its founder.
Now I am noticing that even though all calibration passes with no failure, the gated measurements are not what they used to be - it is very low to almost just room noise. I have tried installing it on a different slot and even with several calibration, resulted no change.

Could you suggest anything?

PS. The regular sweep is working fine and is correct!

Thanks,

Vilic.

This DCX2496 was included with Emerald Physics open baffle speakers. I spend over $1000 having Ric Schultz upgrade it with new input and output circuitry including all RCA jacks. He also upgraded ADC and DAC chips, Vregs, Power supplies, etc. Very musical and analog sounding!

Recently it started struggling to boot up with LEDs flashing rapidly until it completed the startup in 2-3 minutes. I usually left it powered up during which time it never had this problem.

The asking price for a DCX2496 modified by Ric Schultz without any problems has been as much as $1500. I prefer that it be sold to someone who understands this Behringer model inside and out. Includes manual and all my downloaded information about the DCX2496. It will never be worth less than the value of the pair of Lundahl transformers in the input circuit. Moderate scuffing on top and bottom, but front is clean with clear protective plastic still on displays.

$300obo plus shipping.

Greetings from the PNW of the USA. Justin here. Started dipping my toes into higher level audio a few years ago and in the last several months started delving further into hi-fi. Mostly headphones and near field listening. Started out with a Hidiz AP and Shure SE215's. Added a PS Audio Sprout, Grado SR225e's, Music Hall turntable with upgraded Nagaoka MP 110 cartridge, Martin Logan Grotto sub, and some older Mission bookshelf speakers.

The DIY bug has bitten me and I just "built" a pair of Mark Audio Tozzi One near field speakers and added a Raspberry Pi4 with Volumio. Now onto a Pete Millet NuHybrid headphone amp as my first diy amp build. If all goes well plans include an Amp Camp Amp and a diy electrostatic headphone amp and... Lol.

Looking forward to learning and contributing. Cheers.

Is there any reason that a 12AU7 series regulator would not be appropriate for power pentode screen supply? 20mA plate current would seem adequate for a pair of medium power pentode screens and if voltage drop across the pass tube is not huge 2.75 watt dissipation seems OK. Am I missing anything?

mike

Hi All, I never had much interest in OB speakers, but to be fair, I never really listened to them. Well, this past weekend was the AK fest and I sat and listened to the Salk Audio OBs for a couple hours. Now I want to build a pair with stuff I have laying about. So, what are the critical specs I need to look for in the drivers? I have a lot of drivers and would rather go about this with some clarity of thought vs. just trying everything I have to see what works.

Here is what I have so far.

TWEETER:

The old but wonderful Philips tweeter. The back is enclosed so not really OB. Here is 1. the spec sheet and 2. a crossover designed for them.

http://www.troelsgravesen.dk/WWDT_files/ad0160.pdf

WWDT (at the bottom of the page)


MIDS:

The Parts Express PA130 5" midrange driver.... here is the spec sheet

http://www.parts-express.com/pdf/295-010s.pdf


WOOFERS:

And this might work for the woof - I have 4 of them. - CERWIN VEGA S-10.8 10" 8 OHM 400W STEALTH WOOFER

This is all I could find on them

• Woofer Size: 10".
• Frequency Response: 40Hz -500Hz.
• Power Handling: 200 watts RMS (400 watts Maximum).
• Sensitivity (2.83V @ 1 meter): 93dB.
• Impedance: 8 ohm.
• Mounting Diameter: 9.0" (22.86 cm.).

I posted this in the Fun OB thread but then realized that I was highjacking the thread and so I am starting this thread.

Panomaniac posted a number of posts about the RROW and that makes a lot of sense. But, I don't know enough about crossover design to figure a crossover out.

P.S., this is all stuff I have laying around for years if you are wondering why I would chose these componants.

Cheers.