I've been effectively gifted this mid-80's behemoth, and as it turns out I've got some use for it in the later stages of a project I'm working on. Unfortunately, it's got very low voltage limits, and I don't have the requisite pieces parts to work around that. I work on tube amps at audio frequencies.

I've got two 54001A probes - these are active, with 10k impedance, but a limit of 20V peak. Going to have a hard time scoping a phase inverter with that.

I've also got two 54002A modules, which are 50R impedance and a max 5Vrms. Not a lot of interesting places on a tube amp with that little voltage. I don't have probes for these, but they're BNC.

So. I could build a voltage divider to give me 100:1 attenuation and just hook up the 54001A probes to that when necessary. Upside, cheap. Downside, kinda unwieldy, feels kludgey.

As for the 50R inputs, there's a Tektronics 100x (5k) probe that I can pick up on the auction site pretty cheap. But the following input impedance in most of the places I'd be scoping is 1M or more, so sticking a 5K probe in parallel seems like an excellent way to blow up an input. Or maybe just be super inaccurate.

Third option, pop for a pair of 54003A modules ($40) and a pair of 100x probes from Amazon ($20). Upside, it's clean. Downside, I'm limited to 200V peak.

Which of these makes the most sense? And what was HP thinking, not providing any way to scope anything remotely HV?

Hello. Picked up a set of busted B&W DM303's from the OpShop for $25. Tweeter on one of them is 'completely shot - because, well, it is no longer recognisable as a tweeter - probably a 3 year old decided that their finger would look really good INSIDE the tweeter and the shinny metal dome was the chosen point of entry.

Long story short - They cost me $25 bucks. I know they aren't 'fantastic speakers' but, the woofers are fine, and the crossovers seem fine, and I've got a thing for 2 way B&W speakers and this pair would make my 4th set sitting in the living room on a speaker switch.

Currently have in my living room: B&W 601-S3's, 201-V2, DM5's with replacement (recycled) tweeters.

So: I need 2 X Replacement Tweeters to fit DM303's, to match, or closely work with existing crossover. I do not want to 'amend' or 'mod' the crossover as I'm not that fussy as long as they sound 'good.' EDIT: I don't mind 'modding the crossover' as long as you hold my hand and say nice things to me whilst you talk me through it (I can solder like a pro and have heaps of capacitors, and they know by name down at JayCar).

FWIW: I like brighter sounding speakers,

This is a 'cost sensitive exercise' because, lets face it, 20 year old DM303's that cost me $20 aren't exactly 'top shelf' speakers.

Recommendations please. I haven't actually heard any B&W DM303's so no biggie if the 'solution' is different to original B&W spec. Open to options. Opinions welcome.

hey guys and gals,

Just curious if anyone has used these (or similar from elsewhere) sized drivers that seem to be a clone of the bose minilinks.

42mm 4Ω 10w diy full range audio speaker stereo woofer loudspeaker for bluetooth speaker Sale - Banggood.com

tempted to buy a couple either paired with a passive radiator or get 4 and finally try the Iso. Would be interesting to see if i could build something very compact and get some ok sound out of it.

Any views on the subject?

so maybe some of you know is there any difference ?
I simply have a source that can give me GU 19 tubes they dont have the -1 written after the GU 19 are they different from the GU 19-1?
at some pics I see some added caps dishes inside the GU 19 that are not present at GU 19-1 atleast not in the ones I have.

Having trouble with the T1000-1bd, can't get a schematic from RF. The amp is gong into protect as soon as I apply a signal.

looking for a pair of these no need to be matched. to be used in a de-lite amp. already running IXTH6N50D2's in it now.

Thank You,
Jeffrey

I'm still trying to get a voltage regulator on my SSE. I'm now testing to see if the problem is with my amp. Is there any reason this set up wouldn't work? I can't seem to get any sound from the amp (aside from a small pop or two.)

I've tried rebuilding the entire amp with a new SSE board and I've replaced every single passive component (the one exception are the OPT's) and I still can't seem to make it work...

I don't see any problem with this set up, but I'm no expert. If this is a good set up my next step would be to rebuild it in the traditional manner and start from there (the sensible solution.) I just thought I'd try to see if I can get it to work like this before I install all the PSU components.

Thanks,
Glenn

Who has a full build one or a partial kit or half kit?

Thanks Martin

Hi,
I have a problem with a transformer that is humming quite loud now and then. Out of curiosity I started logging the voltage with a multimeter and an oscilloscope. I logged the voltage for 48 hours. The problem is that the results from the meter and oscilloscope are quite different. The multimeter says that the DC voltage has been between -1,067 V and +1,176 V, the oscilloscope says the average voltage has been between -3,7258 V and -2,0095 V.

First, I am not quite sure how to measure the DC component with an oscilloscope. Most instructions on the internet for measuring DC component on the AC line are done with a multimeter. I did some basic test with a signal generator and the oscilloscope; I had a symmetrical sine wave where I adjusted the DC component and the AVG measurement at the oscilloscope gave me the correct DC voltage. I have assumed that is correct to use the AVG measurement. Unfortunately, my mains voltage isn’t very symmetrical, it is quite distorted.

So, my questions are basically:

• Is it correct to use the oscilloscope’s AVG measurement to read the DC component?
• Are there other methods that are better than using the AVG measurement?
• Why are the results from the multimeter and oscilloscope (very) different?

Any other input/comments are also welcome.

I'm making a DAC using a DIYINHK AK4493EQ (768kHz/32Bit AK4493EQ DAC BARE PCB, I2S/DSD input - DIYINHK). It sounds great right now with the lineout. I've probably committed a sin and have wired up headphones directly to the lineout and run at cut volume.

I have dual +-12V (could up to 15V too) rails using a variety of op-amps (opa2134, ad8620, etc.). I haven't been rolling op-amps yet.

What's the recommendation for adding a headphone amp or headphone out? I have a lineout going to a tube amp currently that I am very happy with. I'd like to add a headphone out.

I'd ideally solve for low-impedance IEMs (massdrop plus universal IEMs) as well as higher impedance cans.

Should I go with a single pole 4 throw setup and switch between two lines? If the single op-amp is able to drive sufficient volume

Playing around with wide banders in my HM4750SLF, I used Visaton FRS5X for a long time. I have now tested Monacor SPX-20M and it's excellent for home use. The Monacor have better output in treble and "feels" more detailed.

Anyone able to make a 3d printed phaseplug, it would be even better!

Green is Visaton, yellow Monacor

EDIT: THIS IS A 12V SUPPLY USING A 6-0-6 TRANSFORMER OUTPUT 12VAC RECTIFIED TO ABOUT 18VDC//NEWEST PSU DESIGN ON POST #38**

I have put together a simple tube hybrid headphone amplifier per the plans found here -



NP-100v12: DIY 12AU7 (ECC82) Tube / IRF510 MOSFET Headphone Amplifier





I have also put together an LM317 based PSU using the schematic called out in the data sheet. I keep having a buzzing issue no matter which way I hook up the PSU to the amplifier on the breadboard. When I hooked the amplifier up to a 12V battery, the issue disappears.






The buzz sounds like a 120 Hz buzz and is not influenced by the volume of the source. Could it be from the fact that the transformer and PSU are just sitting out in the open? Do I not have enough capacitance in parallel with the output of the rectifier before the IC? Is there an easy to calculate what that value would be? I don't think this can be attributed to the amplifier itself because even when I placed a 100 µF capacitor in parallel with the power input of the amplifier, it did not help. The PSU was built on veroboard and I believe is grounded correctly. Also, the amplifier circuit is star grounded on the breadboard to the PSU outputs.


What is the best way to start troubleshooting these issues? Is there an established "reliable" LM317 design that is any drastic improvement over the one in the datasheet? I would prefer to nail down this design with the LM317 so I can use it for various projects.






Thanks.

Good day all!

I'm trying to test a pair of 5BL8 tubes but can't find the appropriate settings for my tube tester (Superior Instruments TV-11). The closest listing to it is a 5BL7. Thoughts?

hey all,



newly built set of cnote speakers from PE, both experiencing a HF rise starting around 6.5k


whats good: they both do it, so whatever i botched, i did it consistently, yay!


whats bad: i honestly don't even know where to start digging, and honestly, maybe this just how they are? and there isn't actually anything wrong?



i followed the below diagram to a T. the only variance would be that i was able to get C3 L1 and C4 all to physically intersect without having to have a lead wire between the L1/C3 and C4 (not sure that has any effect) at the common ground


here are my REW measurements of both speakers, again, very consistent between the two (good to see my topping 22 amp is keeping my channels well balanced, shitty pot)


anyway, any help would be great! i have a multimeter if i need to start digging in with that, but pulling the crossovers out would be major surgery as the speaker holes are quite small, and the mounting screws are covered up by the foam lining....

Hello,


my denon amplifier x3300 is giving -64 dc voltage at the power transistor emitter side.As per the manual I should read 0VDC.
The high dc voltage problem exist in SBL, FR, FL channels,

other channels reads milli volts


I checked and replaced the faulty power transistors in the faulty channels.



Right now I am concentrating on the FL channel. screenshots are attached.
The reading in red/blue color are as given in manual.
The reading in green are my observation.


I have replaced the darling ton power transistor pairs and Q409. Also replaced all the other transistors, but still the same problem.


Note: The amplifier board is removed from the amplifier and connected separately for troubleshooting, only DC power supply is connected and the pre input/speaker output cables are disconnected.


Please help

Hi hope that you can help me in the right direction🙂


I am looking for a great looking RCA female input to my amplifier. It would be great if it's also of high quality.
Here below have I shown a female connector that in a way fits the bill, but I think it's ugly that you can see some of the black plastic sticking out. I would like it to look more like on the amps you go out and buy in shops.


The RCA input has to be isolated from the case and solderable on pcb.

I'm in the process of "biamping" my entire surround system and so am in the market for some cheap, high quality class-D amps (those two design goals are not necessarily mutually exclusive!). I've been reading lots of datasheets, ordering a few to play with off aliexpress and then performing measurements as I go along.

I've currently got a "Yuanjing" TAS5630 amp from SHENZHEN CAIZHIXING ELECTRONIC CO.,LTD and, after a single mod, I am very happy with it. And the best part is that it only costs $60!

Free Shipping TAS5630 300W+300W class d amplifier digit amplifier board We are the manufacturer on Aliexpress.com

The design is straight from the datasheet -- even the PCB layout is similar. AFAICT, all the main resistor, cap and inductor values are as recommended. The TAS5630 seems to perform better than some other units I've tried based on chips like the TDA7498, TDA8920 etc. They've also added an OP1632 front-end, so you could use it fully differentially. This all means very good audio performance.

There are a few issues (most easily fixed):
* Noisy out the box.
* One component only rated to 40V, not 50V supply that TAS5630 is designed to handle.
* "click and pop" at turnon/turnoff (doesn't bother me).

When I initially turned it on, the output was very noisy... so bad that I was about to bin it as a DOA dud. There was a lound buzzing that decreased when it was loaded. This is different from the hissing noise associated with cheap class-D designs, so I decided to look a little closer... A bit of sleuthing revealed that the supplied 12V power supply circuit (for OP1632 and TAS5630 GVDD) had a very noisy 10.8V output, resulting in sub-optimal performance.

The fix is simple: replace the LM2575-12 regulator with a LM2575-15 device.

Explanation:
The LM2575 chip steps the main supply down to an intermediate voltage before a linear regulator (LM317) cleans it for use by the input differential amplifiers and TAS5630. Generally, this is a nice design for an efficient, low noise supply. But if the intermediate rail is at 12V (as the supplied LM2575-12 regulates), then the linear regulator is useless as it, too, is trying to regulate to 12V. So you get the minimum forward drop across the LM317 and about 10.8V into the highly sensitive amplifier modules. Crucially, this results in no linear regulation and a very noisy output, with the LM2575's switching breaking into the audio path.

Replacing the LM2575-12 with a drop-in LM2575-15, 15V switching regulator, means that there's 3V headroom for the LM317 linear regulator -- sufficiently higher than its specified 2V forward drop. I have tested this fix on my unit and it has solved this problem. I can't detect any switching regulator noise in the output now. The frequency response is flat and THD+N below my measurable limits.

There are some unpopulated pads on the board for a 12V fan header (regulator is already populated), a couple of LED indicators, reset switch and a "shutdown" header. There're also solder jumper options for PBTL (jumpers pre-installed for two-channel BTL).

The only outstanding issue is that there're some clicks and pops on power-up&down. The TAS5630 itself is pop-free. The problem seems to originate with the OP1632 - TAS5630 interface. The OP1632 is supplied from afore-mentioned single rail 12V supply. It's biased to half the supply (6V). This, of course, changes as the rail ramps up/down. The TAS5630 doesn't shutdown 'till the rail gets to about 9V so there's some 3V change here before the output mutes. I don't care since the amps will be powered 24/7 in my application.

Further, I should point out that the National LM2575 is only specified to 40V input. It is being used outside its maximum ratings if a 50V supply is employed. I only use a 36V supply, so this is fine for me. But if you're trying to squeeze all 600W out of this module, you're gonna have a bad time.

For my application, I'm very happy with it and can recommend this module to anyone looking for a low-cost high-performance class-D unit.

I picked up a pair of these drivers for cheap and have decided to build a cabinet for them.

Link to the manufacturer's page: FaitalPRO | LF Loudspeakers | 18XL1800

Aims:
- Go at least as loud as four of my 15" subs
- Get nice and low - 30Hz would be nice
- Easy enough to move by myself
- Take everything a bridged Powersoft T602 will throw at it

After some playing with Hornresp, I settled on a boring ported box. 250L chamber volume, port of 1000cm^2 area and 80cm long.

That just about matches 4x 15"s (the 15"s put out a couple more dB at 100Hz, but I'm crossing over there anyway), while getting 10Hz lower. Today's super-woofers are impressive.

Now, the cabinet tuning comes out around 30Hz, which means there's a lot of excursion around 40Hz - 27mm peak (Xmax=20mm) if the T602 puts a full-power sine tone there.
So, I tested a driver in free-air conditions with one channel of the amplifier. Cone excursion got to in excess of 50mm p/p with a lot of wind noise, but there wasn't much sign of the driver "locking up" at that sort of cone travel. I actually ended up clipping the amplifier trying to make the driver struggle.

Probably fine, then. Under normal use there would be a few different frequencies happening at once, so I don't think it'll be a huge problem.

The port velocity gets to around 32m/s with a 3rd order 27Hz highpass filter in place. That's a little on the high side for linear operation, but it's another compromise - a bigger port would mean a bigger cabinet, and it's already around 1/4 of the total cabinet volume.

Driven to the ragged edge, this subwoofer will probably start showing compression in the 30-40Hz range, but there's still a lot of output potential there.


See attachments for a couple of drawings of what I've got so far. I don't think there's anything special happening with this design, but I have tried to avoid any bracing inside the port, in order to keep air flow as smooth as possible. The brace against the back panel is a compromise - I didn't want to leave a panel that large free to resonate.

I'm planning on a tip-and-roll setup for moving this around - the form factor should make life nice and easy.

The wood supplier has a 2-3 week wait at the moment, and I'm planning on placing the order some time next week. Stay tuned.

Chris

I have a few old 15" woofers and a lot of odds and ends of compression tweeters in the junk pile. Combined with a few Hafler Transnova amps I have refurbished I thought I might make a few biamped speakers for general yard/pool party use.

If I understand the typical modern speaker that is designed to be biamped (not biwired) when you remove the bars that connect the woofer to the tweeter you are left with a low pass to the woofer and a high pass to the tweeter. I would probably just do an active cross over before the amps and do away with any circuits post amp.

But it occurred to me that lots of modern AV receivers can reassign the back surrounds to be used for biamping the fronts. And they have that automation where you plug in a microphone and they do room optimization. Would they be smart enough to approximate some sort of cross over function in the biamping? Do these tuning systems do any equalization? Or do they just control the relative volumes in expectation that the right cross over is already there?

Best,
John

Hello,


could a LL1691 owner sketch roughly the pin hole layout? I want to use a PCB instead of direct soldering.


JP

Chuck was right for sure.
We lost good hdmi air tv and was getting to the point I considered cable.
But had a hunch, turned and unplugged everything in house just like Chuck.
We then had great air tv again but with cell phones and lights off. Back to candles.

Over the next few weeks I'll gradually figure out how much emi is radiated by each device capable of broadband noise (using an IFR spectrum analyzer).
How much the hifi noise floor is raised is unknown.

The led lighting is top on the list as all of our 'bulbs' are now led.

Best regards Mr Chuck.

i'm new in this foro - And I glad to meet you

I have a 1994 CYRUS III - which is about 26 years old , and until a few months ago it worked perfectly, but it started to give an intermittent failure which consists of:

When it is turned on and the initial check is done, it blocks, not completing it and some leds remain on (Tp-cd-tuerner, volume, etc.), other times, it starts well and after one or two hours, it blocks and turns off and the same leds remain on. The only way to start it up again is to disconnect it from the mains, it will be unblocked and after a few hours it will start working again or it will be blocked.

I have taken this equipment to the old CYRUS technical service in Madrid, which has been for 20 years although it is not now, it continues repairing and checking this type of equipment; they have checked it indicating me that it is faulty:


The front micro - socket whosepannel model is: AM/EP1V3/86 (according to what I have been told about this micro several versions or updates were made - CIRUS / Missión must know it.

They cannot get me that piece but it is possible that cirus has it or some equipment of second hand that this for pieces./scrapping etc.


I had sent to Cyrus UK a note telling this problem from their support page, and they has told me that have not codes and or facilites to repair this ampolifier model anymore

ANY IDEA from US.

I love this Apmpl.

Thank you in advance for your help,

Agustin

Hi guys,

I am about to start a new Tannoy project and need your advice.

The project will be using a set of old Tannoy K3808 (SRM). They will be reconed to K3838 with hard edge, have new HF diaphragms and new filters without controls. Basically only the frame and magnet will remain.

For enclosure I cannot (and will not) build 200 liters+ boxes so my limit is something in the area of 100-150l - and this leads to the question:

Do any of you have experience or information about the following designs for Tannoy 15" taking the relatively small volume into account?

1) Closed
2) Vented with port
3) Vented with acoustic vent
4) Rectangular GRF

Thanks a lot and greetings from Denmark

Here are 2 new blog posts
The first 1 i'm using multiple computers (5) and multiple speakers for testing....

Creating Mayhem | Timo's World all around the globe

The 2nd post is bout getting all speakers to work together by matching their phase responses and eq'ing the whole thing to in this case the X-curve

Creating Mayhem part 2 | Timo's World all around the globe

Enjoy

Hello everyone
I hope all of you guys and ladies are doing well
My questions are these. I’m getting a old organ from someone near me. It’s a old unnamed organ, someone in the past had painted it. I will bringing it home tomorrow and will post photos of it then
I took the back cover off and could see countless small tubes and found the power amp, the power amp has two large transformers and a power transformer. More info on that tomorrow.
What I’d like to know is about the other tube banks. I seen they are labeled on the case
B,C, D and so on. I think they are for the different peddles and keys. For the tones
Tomorrow I’ll post photos of them as well.
What parts are good to save and pass on to you guys for your projects? I know it’s hard to say without the photos and so on.
I do know that I want to keep and use the tube amp for one of my systems. Once I get it out and see what all I can use and what I need to do for safely.
The lady did have it powered up and I could see all the tube glowing under all the years of dust. So hopefully that’s a good sign that it’s useable.
Until tomorrow
Thanks

Got this amp for repair. Amp looks fine. All signals are in place, but it pulls more than 5 Amps. One side of the bank, slightly heating up, and the transformer for that side makes hissing noise. Changed some Capacitors on the audio drive board, because they were dead. Any suggestions?

I have a pair of 420a transformed to 416a with a complete recone kit just completed. I dragged these things all the way from Canada in hopes to use them here in the Philippines along with a nice pair of Emilar 800hz/EA-175 horn driver combination.
I never thought about the high humidity and what the effects would be on the paper cones of the woofers over time. I would surely hate to ruin so, it saddens me but, I’m actually considering selling them. I’m still wondering if I need to keep the tweeters or sell them too.
What would you do?

Greetings fellow diyers.
I´ve inherited a pair or tower speakers from my grandpa.



As you can see, big speakers.. 10 inch woofers, 4 feet tall.

Now look at this.. I´ve been measuring frequecy sweeps with my phone from the listening position. Very little output in the sub bass range.



This is the woofer crossover, I noticed a few caps in series which to my understaning are used to attenuate bass frequencies.





Tweeter and Midrange crossover



My setup: Room is 22x14x8. Big opening on the left side (I live in a loft). Long wall placement.



My grandpa had a passive subwoofer in his system also which makes my suspicious.

Looking at the woofer specs (Peerless 831727) and cabinet size I should be getting flat response to 35 hz with ease! Why am I getting so little bass? Can anyone tell me what´s going on here? Please help!! 😛

Can anyone tell me how subwoofers work? Like I know all their parts and how they work etc… basically….but the only thing I can’t get my head around is this. I know there’s a lot of factors like T/S parameters, box, room etc… involved BUT so many people are telling me that to get loud is “mostly” the factors of sd and xmax correct? You have a specific sd of a speaker and to get louder you feed it more power causing the speaker to move more for more displacement OR you have a speaker running at say 1inch peak to peak and to get lounder you can increase the sd BUT here’s the thing if it’s all about “displacement” is which some people tell me then why is a $2000 SPL sub way way louder than a generic cheap $200 sub…them both having the same sd and xmax thus having the same displacement. I know people are saying well you feed the SPL sub 5000Wrms and the cheap sub 300wrms….but I’m thinking how does that extra energy from the SPL sub convert into audio being having the same displacement?

Dam confused here hahaha 😕
Cheers guys

I ordered and received an Ortofon Red Verso today. Since it was the only Red version the shop I prefer had (and I needed instant gratification). I did however try to find out of that is the version I could fit to my RB250 arm. Since it looked do-able. I got the verso. Guess what? I won't fit the bolt is too short. No biggy since I can just unscrew the top plate and fit longer ones.

Here is my rant though. By using google I could not find a single sentence which arms the verso is suitable for. ( configuration for bottom headshells is the only explanation )

So now when someone googles at least they can find: "Do not order the Verso for your RB250 unless you want to diy". I ordered m2.5 length 6mm and 8mm now. Since the bolt that comes with it is 4mm.

Rant and info over. I'm curious about the experiences from other owners of the Ortofon Red.

Hi.

Raspbian is now called Raspberry PI OS.

And a full 64bit Beta is available.

Finally. A 64 bit version.

Having a full 64bit version - kernel and userspace - are good news for us RPI4 owners.

I'm running my own 64bit Arch Linux since quite some time. It works really well.


These folks who run e.g. Moode can look forward to it, if of course Tim and the other OS folks decide to go for it. Maintaining a 64 and a 32 bit version could mean a lot more effort to them.


Enjoy.

Re: Se 2a3 golden era

in february 2020 I had the pleasure of mounting a SE 2A3 without compromise on a high-end black aluminum chassis

the transformer feeds the GZ32 valve, our CIFTE nibs, the smoothing choke and the head oil condos and the filtering JJ are common to both channels, then a 10H 100mA choke and a 2X100uF 500V F £ T condo per channel for conventional power supply. Y.

the 2A3 are heated alternately with a hum balance reostat which can also be measured in AC by the rca TPs at the back at the same time as the cathode voltage in DC

the 1: 1 IT is loaded by triode 6C45P-E.

the supply resistances are with wire wound the cathode resistors 2X2 1500ohm 10W and the 220ohm 5W wound audiogold ceramic non inductive non magnetic

the cathode capacitors of the 2A3 oil paper 30uF 160V and BC 100uF100V

high quality 3K5 42H 135mA output transformers

the sound is just superb beautiful

DIY mates, I got the bug listening to some B&W 800s and want to build another set of speakers! I'm not asking to clone them but I do want to make something that can sound great even loud. While I may use a subwoofer for movies, I don't plan on it for music. Let's call it a mid-life crisis speaker build.

Here's what I'm liking so far
Tweeter: SB29RDC-C000-4
Midrange: NE149W-04
Woofers: 2x SB29NRX75-6, SDF-250F75PR01-06, or SB Acoustics WO24P-8
FWIW, I have speakers with dual RS225-8 now and they sound fantastic but don't get as loud as I'd like.

Let's be engineers about this and be critical when needed.

I am planning to use a miniSHARC processor into 8ch of amplification to run them active and choose my crossover points, but I may want to design a passive crossover at some point and the total impedance should be around 4ohm.

Great thread but want something that really shakes the room and sounds effortless doing so.
Open Source "Tower XL" thread

Hi all I haven't been soldering in many years now....but....

I need a preamp for my Pass F5 I built years ago, just as it is not quite loud enough. I have looked into the prospect of building a slightly more powerful version, but I'm not sure my heat sinks will be up to it, and the amp is so stable and reliable I don't want to mess with it.

I found this PCB for a "Pass 2.0" preamp on eBay. I wonder if this is the unbalanced version of the famous P 1.7 preamp??

SE class A MOSFET unbalanced + 128 step volume control preamplifier PCB ! | eBay

Any ideas? Thanks
Lucas

Hi all,

I am hoping to build a Baby Huey EL84 this year and am in the process of sourcing components.

I am thinking of using a Russian equivalents of the 12AX7 and EL84 vales / tubes as they are plentiful at good prices.

As the output is 10w I am wondering what speakers people are using to work with this design. What sensitivity etc works best with this?

Would people be willing to post pictures of their completed builds and speakers they are using?

Thanks

Lee

Hi to all people,
Sorry if my question is on wrong place or copy, I search but I cannot find this thread.

I have an Revox B250-S amplifier, I'm very happy with that, but it's time to replace the electrolytic capacitors. This was done, now problem is gone, but by the way, I found a couple of discussions about replacing op amps, so please let me ask you if any of you have any advice will I try to replace the existing RC5532A op amps with something better?
Thanks in advance.
Regards
Leo

I have just sent an email requesting the deletion of my account at diyAudio.

I do this with regrets. But in the last couple of weeks i became more and more convinced that a lot of trolling and/or usage of multiple accounts by the same person is going on at diyAudio. This makes it hard for me to keep interacting in a polite way, so i saw no other option.

Greetings,
Robert

Greetings!

I am building a guitar amp and I need a power amp of 100 W in 8 ohm. Would the folowing schematic be good, those videorrocola people claim it to be. Or would j be better of with a cheap tda7293/4 board from ebay? I dont need an amp that is high fidelity i need an amp capable of sustaining power without burnig out as i will mainly use it for metal. I would kindly ask for your Professional opinion on this.altough a really doubt that this amp is capable of 100w into 8 r, mainly beacuse of5200 transistors at output. 🙂
Link to schematic : construya un amplificador monofonico de 100 watts version 2.0

Just want to mention how grateful I am to see this site's feel and look had not changed over the years. That's almost 10 years!

Another popular local forum here had done yet another upgrade which is absolutely confusing to use and all external links broken. It is frustrating. We just want to build speakers not learning how to use a forum every year 😎

Cheers!

Hi,

I'm building my second VT power amplifier (designing first). It consists of
- two OPS boards
- two DRIVER boards
- 6.3VDC PSU (DRIVER heaters)
- AC power control board
- 5V/12V PSU
- 120VA transformer for heaters
- 200VA transformer for HT and bias PSUs
- two toroidal CFB OPTs from toroidy.pl
- metal chassis
Maybe there will be also
- one analog meter for bias setting
- remote control board (on/off, volume)

Almost all components are ready. I'm about to design DRIVER board and I want to know your opinion. There are two DC coupled LTPs supported by CCS and powered by mosfet regulators. First stage E88CC, second stage E88CC or ECC99, heaters have configurable jumpers. Regards NFB, you can have global or/and local "Schade" feedback.

Hello,

I am in the process of designing a PecanPi DAC module that I already have a customer for. They are purchasing 100 of them.

I am putting this here to see if anybody else would like to join in to purchase these modules. Each module will be about $200 each. I will have final pricing in the next two weeks or so. The price will be lower with more buyers.

The modules will feature dual PCM1794A DACs in monaural mode and have specifications identical to my company's PecanPi DAC.

The module will have:

• Balanced and single-ended outputs.
• The input power supplies will be +/-12V (analog) and 3.3V (digital)
• The size of the module will be 74 by 64mm as per the attached drawing.
• The input signals will be I2S at 3.3V and support up to 24/192.
• The modules will use my proprietary dual differential output stages with OPA1612 op-amps.
• Complete reclocking with Crystek femtosecond jitter oscillator

Working on a DAC and would like to provide both BNC and RCA connector options for the single S/PDIF input. Can they be in simple parallel, sharing a common 75 ohm termination resistor, with one connector always left open? Or is there some reason this is not advised? TIA

I'm pretty sure this is a First Watt clone but have no idea which one.

Help appreciated!

Thanks,
Sam

Having read through the BIB thread a few times I'm really tempted to build a BIB for the 5" Monocor driver.

But my question is this, how many here have heard the Monocor in the BIB enclosure?

What's the consensus if any, of how it rates vs the Tangband drivers?

Are there any other low cost drivers that should be considered?

Thanks in advance.

Rick

Just bought a new cheap H/T amplifier.
Not Dolby Atmos, just an old HK 1710S. If using the 2 channels from the 7 available for Front Height and using some spare centre channel speakers is it better to use then vertically oriented or horizontally?
The speakers are nothing special, just Sansui WTW using 5" drivers, I have however blocked the rear firing posts and stuffed with fibre as they sound cleaner that way

I'm selling my LX521.4 because I have moved and I do not have space for this system to work properly.

I could finish this project during lockdown but I cannot keep this system and The Loudspeaker together.

They have been built with CNC and laquered in black and white.
Everything is in perfect condition and the speakers have been used less than 20 hours. I could say they are new condition.

The amplifier has 10 Hypex Ncore MP channels + 2 minidsp 2x4 balanced programmed with the latest crossover for the LX521.4:
Each speaker as follows:
Hypex NC252MP 2x250W (one channel for each subwoofer)
Hypex NC122MP 2x125W (one channel for midwoofer and one for midrange)
Hypex NC100HF 100W (for tweeters)
Minidsp 2x4 Balanced

Connections between amplifier and speakers has speakon connectors.

I'm selling the speakers in 3000€ and the amplifier with DPS integrated for 2000€. All the cabling will be included with amplifier.

This is a superb price, shipping (very heavy) is not included but I would paletize everyting safely.

Estimated shipping within EU is about 180€.

Hey all,

I'm looking into making a pair of speakers at the moment and I'm almost there with it, however the bit I'm a little stumped on is picking the right crossover.

I'm looking at using the dayton audio 7" RS180-4ohm, with the B&C DE250 1" 8ohm horn.

I've seen a few things saying that Eminence PXB2:1K6 2-Way 1,600Hz would be a reasonable crossover board, but thought it would be a good place to ask on here.

Does anyone have any advice on how to pick the right crossover?

Thank you all in advance for your help.

Charlie

Pretty much a beginner. I made a set of DIII's back in 2003 and now have the DIY itch again. . I have looked at many designs, and my first question is about picking one to build. I am interested in speakers primarily for music (mainly classic and hard rock). I do not care about home theater sound such as the explosions and dinosaurs walking around.
I have seen some designs that began as a two way and then developed into a 2.5 or three way by adding a third driver and a larger floorstanding cabinet. This makes sense as a way to add to the low end. My confusion comes from many of the two way bookshelf designs being demonstrated with one or more subwoofers. What is the difference,sound wise, when comparing a larger floorstander with a bookshelf and a subwoofer?
Thanks much

Dug up my zen v9 board...to continue with it. Bought in 2006. Copper tracks were tarnished. Covered with Heinz Tomato Ketchup...left for 15 minutes...rinse.

One done the other not.

If you use search you can see that this topic pops up time after time. I am a bit bored at work, so I decided to crate this thread, so it maybe be useful for a new DIYers.

So, thermal conductivity what it is and how to change among many insulators on the market?

Thermal conductivity is a number which characterizes ability of a material to conduct heat. Based on empirical Fourier law for homogeneous media,



thermal conductivity is equal to amount of heat going through a unit area of a material per unit of time at a given temperature gradient (K/m in SI) across the sample.
Thus, we want this coefficient to be as big as possible! As close to one of aluminum (~200 in SI units).

So, how to compare? - Simple! Just assume that we are satisfied with the Fourier expression, than:


Just plug in the numbers from data sheets for thermal conductivities k_i and pad thicknesses h_i and calculate 🙂.
There is a tricky question with the temperature difference delta T(between transistors case and heatsink) as it will be smaller for the pad with bigger k. However, even simple estimations will show you that (fortunately or unfortunately) there is not so much difference between different pads on the market! The best is Beryllium oxide (thermal conductivity is close to aluminum), but toxic and impossible to find, but all others -- almost the same. REMEMBER, I AM TALKING ABOUT GOOD STUF: Kapton, sill-pad A2000, aluminum oxide, etc.
So if you are new in the field and choosing, pick something and start building already! 🙂
Another important thing: air has pretty bad thermal conductivity, so you want to use a thermal grease to fill in roughnesses between your solid surfaces and the pad. OR, use sil-pad a2000( mouser and digikey have them), they are soft and do not require any grease. That what I do and result is good.

Hope it helps 🙂

I have a matched pair of Northcreek Audio D28 tweeters that were used in a pair of monitors. The front bezels were painted silver. $150 for the pair shipped anywhere in the lower 48 states.

Please DM me for more information about purchasing the tweeters, Seas W18NX001 woofers, or crossover kit for the speakers as shown.

Could anyone help me identify these speakers? The seller is indicating that her father-in-law built using a set of plans.

Thanks

Hello everyone. I recently finished a recap on a H/K Citation 11 preamp. It sounds very good but am noticing a fair amount of crosstalk if (let's say) I incidentally have a tuner playing and am listening to my TV's audio through AUX1 (or something similar) Is this normal? Also, I am occasionally losing my left channel audio. Interestingly, I found the fix is to turn the power pushbutton "off" and while the audio slowly starts to fade out after a couple seconds, if I toggle the "audio equalizer defeat" button on/off while the audio fades out, I can restore audio to both channels. I cleaned all the switches with plastic-safe contact cleaner and followed up with De-Oxit afterwards while I had the thing apart performing the recap. Maybe another switch clean, or perhaps new switches are in order? Anyone else have these problems with their Citation 11 preamp? If so, what did you do? Thanks.

I really suck at visualizing things. I work in a noc and am not dumb I just need help with things like this lol.

Can someone run a box design program and provide me the dimensions, cuts and number of 4ftx4ft baltic birch panels 3/4" I would need to for a 16"x16" footprint box. Subwoofer and slot port (full width, 1.5" thick for ease of using two sheets of birch for spacers) on one of the 16 x ? sides.

So it would look something like https://images-hpca.netdna-ssl.com/D.cache.dpthmbn/116/480.jpg

But I would have the port on the floor and it would be much taller I'm assuming (probably over 30" which i'm fine with)

I would like it to be 2.5 cubes internal volume, the driver displacement is roughly .25 cuft. I plan to put in one or two horizontal braces but will be more of a cross, so maybe subtract another .2 cubes for that?

i would like a tuning frequency of about 20hz. A little lower is fine, I would like the height to stay under 40" if it is possible to fit the port inside a 40" box.

I'm sorry to call on you my first post, but I've tried several of the online tools for this and I just can't get it to understand what I'm wanting and spit out measurements I need for my cuts. And the one I did get it to work on I don't trust and now can't find again and it still wouldn't tell me how many sheets I would need to complete this project.

And of course if you need more information from me please let me know.

I purchased an assembled SSE on an online auction site. I knew it had the led mod for the 12AT7. But once receiving the board, checked the SSE for correct parts, and found some differences. I contacted seller, he had no clue. Evidently an estate sale. I am wondering if the differences relate to the led mod. So before connecting power to the SSE I am looking for info/advice on what the changes will do.

Changes:

LEDs instead of C10,C20 & R10,R20?

R12,R16,R22,R26 220 ohm installed instead of 100 ohm?

R13,23 470 ohm installed instead of 330 ohm?

R2 220K ohm 2 Watt installed instead of 150K ohm 3 Watt?

R4 330K ohm 2 Watt installed instead of 150K ohm 2 Watt?

R3 22K ohm 2 Watt installed instead of 10k ohm 1 Watt?

R17,R27 500 ohm 5 Watt instead of default 560 ohm 5 Watt?

PE has deal of it today only for $35, original is $87. Is it good for building a 2-way speaker?

link:Wavecor TW030WA08 30mm Textile Dome Tweeter with Rear Chamber with Ferrofluid 8 Ohm

I am considering a high-end preamp/dac build and was thinking what would give me the best results when choosing between a high-end op-amp and discrete components like a JFET differential amplifier with a BJT push/pull output stage in class A mode.

I can see that a lot of hobby builders tend to use the discrete solution, but I can also see that some of the high-end Op-Amps are hitting distortion and noise figures that i would think is hard to beat like the OPA1612 with its 1.1nV/sqrt(Hz) and 0.000015% THD or the OPA1642 if JFET is the way to go.

In this case I would like to see some real arguments, so if we keep religion and feelings out of the discussion and keep to facts, what would be the better solution in a pre-amp/buffer stage, and would there be audible differences in performance?

Hello,
Last week i got a Cardas 5 pin din phono plug from a well known audio parts seller. Not the economy model but the expensive one.
See the photo in the attachment. Could this be a Chinese copy? Will send a photo to the Cardas company too.
Greetings, Eduard

Hi friends!

Recently I finished my first project, a two way monitor with sb13pfc25 and sb26stc. I was surprised how good those cheap drivers were sounded and I want to try something better from sb acoustics.

First of all I have zero designing skills so I will have to build a satori monitor based on someone others design.

Joachim Gerhard's kalasan is the earlier version of sb acoustics Ara as far as I can tell, so is a design by a proven designer. The only drawback is that the cabinets are complicated but I think I can biuld them.
ARA – Sbacoustics

The other design is from a Czech designer, it seems good and it seems easy to build, but I am not familiar with his designs.
JurKo :: Pkaudio

My third option is a design from a polish forum. The designer is the same person who designed the sb13 monitors that I build and I am very happy with their performance. My drawback is that the crossover seems to be complicated, with many components and many components make me think that they draw power from the amp and they suck tone from the speakers.
Projekt AVS 2018 - SB Acoustics Satori TW29RN-B + MW19PNW-8 - by Tatami Audio

Another option under consideration is sb revolution mini by Jeff bagby. The sb29sdac edition. My drawback is that the mw13p is small driver and the Tweeter is not satori line. Also there is a beryllium option but is out of my budget.
SB Revolution Mini Be Loudspeaker Kit - Meniscus Audio

Last design under consideration is the sb acoustics bromo. Not from satori line, but the reviews of the drivers are excellent and the distortion plots are probably better than the satori plots.
BROMO – Sbacoustics

I know many people will suggest kairos/adelphos but I am from Greece and buying kairos/adelphos kits
are available from meniscus but with shipping and customs will cost me twice the money. (sb revolution mini is open source)

I am open to your thoughts and suggestions! Thank you all!

Hello!
What type of output device the Borbely Millennium use? And how many for each monoblock?

Anyone has a part list or manual to share?

Thanks!

Hi all,

I have a tape machine that I suspect has a noisy sel-sync preamp. What sounds like white noise is happening when I engage the sync function on the transport.

(Sel-sync allows the record head to act as a play head.)

The machine is an Ampex ATR104. I've eliminated the possibility of the head, firstly because it happens without any transport function (i.e., tape is stopped) and secondly, I swapped out the channel's cards for another and the problem is following the card. Card in question is the Main Audio

How would I go troubleshooting this circuit? I was hoping to signal trace to find the noise. However, the signal is noisy starting right at the input and the way through the output of the preamp.

Any advice/tips?

Some links to give some hints:

Schematic (pdf page: 34, manual page: 6-43/44)

Theory of Operation (pdf page: 52, manual page: 4-48)





Best,
Chris

So I have this amp. It powers up and has output. However when I switch phase or subsonic filter it kills output and drive, but after recycling power the output is restored.

Also,checking the +/- HV from Power Ground I read -57 -HV and +28 +HV with signal applied. Without signal -30 +HV and -50 -HV.

What am I not getting? Is this normal?

I found a older thread where Perry Babin posted the schematics dated 6/19/2000. The Manufacture date for this amp is 8/11/2003. The schematics show twelve MTP75N05HID for the power supply mosfets. The amp has sixteen IRF3205 mosfets. Do I have the right schematic for this amp? If not does anyone have the version I need? I realize I can go to RF for older schematics, but if someone has it handle I would much appreciate it.

Bill

Hi all,
First time posting in this forum , I could do with some advice on how to improve my speaker build both aesthetically and with sound quality, if possible.

I built my speaker enclosure based on this design YouTube

I'm currently using a Raspberry Pi4 , a Hifiberry Amp2, a peerless PLS-65F25AL01-04 full range speaker driver and 3 Gpio buttons.

I am using Moode audio for the software side of things which runs flawlessly , I did have a few hardware issues with the Gpio buttons having false triggers , which I resolved by soldering on a low pass filter modification to the Gpio header of the Amp2, details can be found here on the Moode forum Small Speaker project, Gpio problems and how I solved them

I built the enclosure a shade under the size required for the speaker driver , based on an online calculator, however the port is the recommended size. I don't think this impacts the sound quality to much as to be honest the speaker sound great.

Ok to the matter in hand , I could do with some advice on how to improve my build ! , my wife would prefer the enclosure to be smaller if possible so any advice on how to improve the enclosure aesthetically, how to make it smaller if possible , how to tidy up the low pass filter modification, a possible alternative speaker driver to aid making the enclosure smaller or any advice in general would be very much appreciated

thanks in advance .

This is for inmate turk 182 "where did you find that product literature!? sometimes it's next to impossible to find old pre-net stuff unless someone preserved and uploaded it."

I have two pamphlets from the 70s Heil Sound. first one:

I've been recommended to take Syncsource out to improve how SRM12X sound.

Is that a good idea at all, and how is it supposed to affect the monitor's sound?

I love them as they are, but quite curious if/how they can be further improved...

I'm trying to find out what type of cable jack this is. It initially looks like an XLR 4 Pin, except that the pins are spaced out differently and shape is also different (someone else has also confirmed it isn't an XLR). Can anyone ID this cable type since i need to order an L shaped version...thanks

Quick question, if I have a power tube that is wired in the conventional configuration where I have a 1K resistor going to the screen from B+ and I want to convert it to UL at 40% tap, do I still need the 1K resistor or does the UL tap now go directly to the screen given that it is at 40% tap?

Thanks

Hello. Currently i have Pass labs Aleph j as my primary amp. I consulted with Troels about suitable speakers and he offered either Tqwt or Seas 3-way classic. Could someone who has listened to both projects tell the difference in sound. Music styles: blues and rock

Hi all,

Found this forum recently and wanted to ask a few questions, as I'm looking to take my first dive into DIY Audio. I got interested in this whole thing after investigating making custom headphone cables and trying to figure out exactly how the DACs/Amps/Headphones on my desk work. Been a long time musician and music lover. Looking forward to talking with you all!

Cheers,

Press

Damaged Outputs. Looking for A1294... Anybody have replacement. I cant find them at mouser..

Hello,
I am trying to model a raw DC supply. On hand I have Hammond 166M12 (12.6 Vct, 3A, 13.8 ohms), bridge rectifier (1N5822), C1=320 uF, L1=0.6mH at 0.7 ohms, C2=15,000 uF//15,000uF, for a CLC config filter.
I tried the simulation with 200mA sink as load no problem. But if I use 1.0 Amp load, I have to specify that it is a "stepped" using 1.0 for the first and say 100mA for the second to work or else it give me an error saying sink to zero. Am I doing it correctly?

Also, I want to try it with Hammond 166L4 (14Vct, 2A). My goal is to get as close to 15Vdc out without changing any component except the transformer. Can someone show me how it is done?
Thank you!
Abe

I’m looking for a 10mm diameter latching push button 240v 8amp switch. I have looked on RS and Mouser but cannot find what I am looking for. I want just a cylinder coming out of the face of my amp like the amps from the 70’s and 80’s. At the moment I have 2 metal toggle switches that I don’t like the look of so I want to replace them. One to a rotary selector switch and the other with the switch described above.

Any suggestions would be super helpful.

Thanks

Hello - I'm wondering if someone can help me with some advice.

I have a Musical Fidelity A370 Mk1 that I have had from new - it hasn't had any work done on it. I mothballed it a while back as a refurb project because of strange noises (even stranger than usual) through the speakers after switch off and unpleasant hot smells (which I now think were due to dust).

I've opened the amp up and found the forum here where there seems to be some good knowledge about the amp, especially https://www.diyaudio.com/forums/solid-state/139711-musical-fidelity-a370.html.

My plan is to replace the big power supply electrolytic caps (following the advice on the A370 thread) but I have a couple of questions. I am a (digital) electronics engineer so have a reasonable range of test equipment.

1) The amp boards have a number of electrolytics caps on them. Electrolytics in seem to have relatively short lives compared to other component types so should I replace all of these?

2) In the A370 thread Don / AMV8 and Jez talk about adjusting the bias. There is a 100K preset pot on the amp boards which I guess is the bias adjust but I don't want to randomly turn the pot, presumably there is something I can measure. How do I set the pot 'correctly'?

Many thanks to anyone who can help

1) A pair of NEC 12AD7 vacuum tubes. The 12AD7 is a low noise, low hum variant of the 12AX7 and is a drop in replacement. These tubes, made by NEC Japan, have angeled halo getters. They also have matching "4Z" codes and have been tested on a restored and calibrated Sencore TC-142. The results are as follows:

Shorts: PASS
Grid Leakage: PASS
Emission:
Tube 1: Triode 1: 91% Triode 2: 91%
Tube 2: Triode 1: 92% Triode 2: 92%
In addition these tubes have had a life test performed on it which entails reducing the filament voltage of the tube under test by one step and noting any significant reduction in emission performance. Both triodes of both tubes performed excellently.

I would like $60 plus shipping for these tubes.


2) A trio of 6679 12AT7 tubes manufactured by RCA. The 6679 tube was originally manufactured for mobile communication and maintain output even with variations of filament voltage. They are equivalent to a 12AT7 tubes. These tubes have square getters and all three have the date code of "6122" which equates to the 22nd week of 1961. These tubes have been tested for shorts, grid leakage and emission on a restored and calibrated Sencore TC-142. The results are as follows:

Shorts: PASS
Grid Leakage: PASS
Emission:
Tube 1: Triode 1: 102% Triode 2: 103%
Tube 2: Triode 1: 102% Triode 2: 102%
Tube 3: Triode 1: 102% Triode 2: 102%

In addition these tubes have had a life test performed on it which entails reducing the filament voltage of the tube under test by one step and noting any significant reduction in emission performance. Both triodes of all three tubes performed excellently.

I would like $50 plus shipping for these tubes.


3) A pair of General Electric 12AY7 tubes. These tubes have angled square getters and grey plates. They have been tested for shorts, grid leakage and emission on a restored and calibrated Sencore TC-142. The results are as follows:

Shorts: PASS
Grid Leakage: PASS
Emission:
Tube 1: Triode 1: 95% Triode 2: 94%
Tube 2: Triode 1: 95% Triode 2: 95%

In addition these tubes have had a life test performed on it which entails reducing the filament voltage of the tube under test by one step and noting any significant reduction in emission performance. Both triodes of both tubes performed excellently.

I would like $40 plus shipping for these tubes.


4) A Mullard ECC81 12AT7 vacuum tube. This tube has a square getter and has the code sequence Tk1 B8F with the "B" signifying the Blackburn, England Mullard plant where this tube was produced. This tube has been tested for shorts, grid leakage and emission on a restored and calibrated Sencore TC-142. The results are as follows:

Shorts: PASS
Grid Leakage: PASS
Emission:
Tube 1: Triode 1: 100% Triode 2: 99%

In addition this tube has had a life test performed on it which entails reducing the filament voltage of the tube under test by one step and noting any significant reduction in emission performance. Both triodes of the tube performed excellently.

I would like $25 plus shipping for this tube.


5) A pair of RCA 12BH7 tubes. These tubes have long, grey plates and halo getters. They have been tested for shorts, grid leakage and emission on a restored and calibrated Sencore TC-142. The results are as follows:

Shorts: PASS
Grid Leakage: PASS
Emission:
Tube 1: Triode 1: 94% Triode 2: 93%
Tube 2: Triode 1: 97% Triode 2: 97%

In addition these tubes have had a life test performed on it which entails reducing the filament voltage of the tube under test by one step and noting any significant reduction in emission performance. The second tube showed a slight reduction in emission but this was not excessive.

I would like $20 plus shipping for these tubes.


6) An RCA 6201 12AT7 tube. This tube has triple mica construction as well as black plates. It has been tested for shorts, grid leakage and emission on a restored and calibrated Sencore TC-142. The results are as follows:
Shorts: PASS
Grid Leakage: PASS
Emission:
Tube 1: Triode 1: 102% Triode 2: 102%

In addition this tube has had a life test performed on it which entails reducing the filament voltage of the tube under test by one step and noting any significant reduction in emission performance. Both triodes of the tube performed excellently.

I would like $20 plus shipping for this tube.

Under
A New High-Voltage Regulator
is mentioned an easy to realize high voltage regulator - go to the third schematic.
For the TIP 150 I want to use a version with an isolated outline like TO220F (MJF13009) or SOT186A (BUT18F)
Unfortunately the Hfe of MJF13009 or BUT18F is too low.
Maybe there are a direct replacement for the TIP150 in the wanted outline.
Thank you for an advice.

sorry guys. i edited the thread and the price was a typo. it is not worth my time and effort to ship this so it goes into basement.

I'm recapping a preamp. The DC voltage across two 2200uf/63v in the Powersupply, read 38v. AC between the positive terminal and ground is 34v.

Is it ok to replace them with 2200uf/50v caps? The actual output voltage to the rest of the circuit is about 58v.

Thanks

Hi. For Sale what I believe to be an earlier version of the Core AudioTechnology integrated amplifier. This amp is working completly into the digital domain from the USB input to the speaker outputs, with digital volume control as well. It has also a 'high Current' Core AudioTechnology power supply.

It has what I beleive were optional analog inputs (3) and an anlog output.

I don't have much info on this unit other that it is functional. Maybe if you contact Core AudioTechnology they can give you more info.

Part of an Estate sale, not my stuff, but there may be some curious guy here that want to work on this amp. The chassis is rather nice darker brushed aluminium, rear speaker binding post are CMC I beleive, as well as the optional analog output. Just the price of parts, and chassis are probably much higher than the price asked...

Asking 100U$ O.B.O. + shipping + 3%Paypal fee.

As for shipping the unit is large, but quite light, so shipping cost may be not that bad...

Thanks for looking and let me know

Thanks
SB

Hi to All,
Sorry for the long post. Feel free to exercise tl;dr.
Similar to a lot of folks here I have been a music lover all of my life. I went the upgrade route in my early 20's, ultimately arriving at a Linn Sondek LP12 and Linn Ittok LVII with a Dynavector Karat Diamond. I had a Musical Fidelity Mk II preamp balanced out, feeding 2 Quantum monoblock 140w amps and my best speakers were Celestion SL6s, tho not in my front room. I also built a Velleman K4000 valve amp but smashed a valve and blew it up one night after getting a static shock off the Sondek (I am not rich! Everything I have had I have had to work and save for). I have since given it all away to a friend who has spent a small fortune 'upgrading' it. He even had my KaratD re-coiled despite Dynavector saying it was 'consumable' and couldn't be done, (one downside is that it puts out less mVs now than it did, which wasn't a lot).
I have since got into dacs through my interest in pcs and in particular the Raspberry Pi. I have used a Iqaudio and Allo Boss Dac. The latter was powered by a dual out Power Bank feeding them both separately. Unsoldering and resoldering a 0805 0 ohm smd was a challenge with these eyes and a soldering iron tip like Sequoia! I have since got myself a Dual Mono ESS9038Q2M Dac, FifoPi, Ess controller and standard I/V output board. I just received my new Crystek crystals from the US, ordered Monday and they arrived Today! 3 days! That is quicker than RM getting something from the north down to me.
Sorry for the long post but I don't get out much, or not at all these past 9 weeks; 3 weeks to go.
Keep Safe, Keep Well.
Match.

Does anyone know the exact PN of the phones vol ctl pot? Either that or a drop-in.
All I know it is a dual log pot 10K. It is bad, and it doesn't seem I can easily deliver Fader lube inside, plus with dead zones I am not even sure it will work. Scratchy as heck.
The last and the least important touch on a unit I have just restored.
But if at all possible, would like to fix that one also.