Audio grade capacitors question

[p5200]

I have an old Adcom stereo preamp which has some capacitors that I want to replace because of age the board says 1989. The ones I want to replace are discontinued Panasonic HF low ESR series there are 4- 470mf. 35v. and 3 1000mf. 25v. They are all the same physical size measuring with my calipers,  31.75mm H x 16.25mm diameter. five are side by side with about 1/8" gap between them any ideas of a new series of Panasonic or similar quality brand that would fit these requirements would sure be appreciated.  Thanks!    

[c4757p]

I have an old Adcom stereo preamp which has some capacitors that I want to replace because of age the board says 1989. 

Any reason to believe they're actually bad? 1989 wasn't that long ago...

[p5200]

I don't think they are faulty since the preamp seems to work fine but I have been upgrading and replacing other components and just thought I would replace those too.  Thanks!   

[don.r]

Most of the bad caps from that era were exposed to hot environments like power supplies, monitors or computer motherboards. I would think a pre-amp is relatively cool.

[rdl]

I don't know if you match the sizes exactly but take a look at the Panasonic FR series.

http://www.mouser.com/Panasonic/Passive-Components/Capacitors/Aluminum-Electrolytic-Capacitors/Aluminum-Electrolytic-Capacitors-Leaded/_/N-75hqwZscv7?P=1yzvjj0Z1z0yp75

[p5200]

Most of the bad caps from that era were exposed to hot environments like power supplies, monitors or computer motherboards. I would think a pre-amp is relatively cool.

This one runs pretty warm since it is pure class A.   

[p5200]

I don't know if you match the sizes exactly but take a look at the Panasonic FR series.

http://www.mouser.com/Panasonic/Passive-Components/Capacitors/Aluminum-Electrolytic-Capacitors/Aluminum-Electrolytic-Capacitors-Leaded/_/N-75hqwZscv7?P=1yzvjj0Z1z0yp75

I'll check those out. 

[commongrounder]

I rebuild vintage audio gear as a business.  Adcoms from that time frame can definitely have degraded capacitors (low value, raised ESR).  I almost exclusively use Panasonic FM or FC series caps for replacement, in the values that are available.  For the large power supply caps, I'll use Nichicon or Mallory.  Freshening up these parts can really improve the sound quality of an otherwise great unit.

[c4757p]

For the large power supply caps, I'll use Nichicon or Mallory.  Freshening up these parts can really improve the sound quality of an otherwise great unit.

Freshening up the power supply capacitors improves the sound quality?



I suppose, if it wasn't working at all...

[Phaedrus]

Of course! High ripple increases the quantum tunneling in the op-amp boost stage which makes the jitter factor increase by up to 2dB/mV!!!

[free_electron]

i think we should try to convincen the audiophile community to upgrade the circuit boards instead.
like re-make the bare board but use higher quality dielectric and thicker copper.

and then they can desolder each and every component from the original and transplant it to the newly etched board.

that will keep em busy for a good long time and off the forums with silly questions

[commongrounder]

Hey guys.  No magic here.  I go through these units and test electrolytics for problems with value and ESR, both of which can have an effect on low frequency response and decoupling/crosstalk.  You would not believe how many big power supply electrolytics I find that are so dry they sound like a can of pennies when you shake them (and the amp was still working at the reduced capacitance).  You bet replacing them improves the sound and power output.
I am definitely not a believer in esoteric cables, mysterious magnets, etc.  I quantify problems and solve them.

[SeanB]

I recapped a few old units, but only those capacitors that were truly faulty. If the in circuit ESR was under 2R i left them alone, except for the big power supply capacitor which looked well worn, and which was close to open circuit. Rubber bung was perished. Funny enough the preamp that one was in still worked pretty well, and had very little hum, though with the new 2200uF 35vcapacitor ( was in the bin and close to size, plus the original used a series resistor with the half wave rectifier diode used to supply the -26V it used) it would continue to work for nearly a minute after turning the power off before it started to distort audiably and clip before going silent. Panasonic used PNP RF transistors in that one, it probably will still have a response in the MHz region, let alone audio. 400MHz ft parts in an audio unit? At least they all still work.

[Conrad Hoffman]

If the cap values are going down (or up- very common) or the dissipation factor is high (I refuse to deal in ESR, that's for switching supply folks), get 'em out of there. If the value and loss are OK, don't expect any improvement. Also, if the value and loss are OK, and you don't see any physical problems, the chances of that cap failing any time soon are minimal. Here's a hint. If you want low dissipation factor, and the part will fit, go up a voltage level. If you look at the manufacturers data, dissipation factor decreases as voltage ratings go up, at least to 63 or 100 VDC. I'm not suggesting putting very high voltage caps in low voltage circuitry, but I will always avoid the poorer performing 6-16 volt parts and use 25 or greater. Very low voltage caps also seem to fail sooner. There are also some linearity benefits and no significant downside to staying away from the lower voltages.

[p5200]

i think we should try to convincen the audiophile community to upgrade the circuit boards instead.
like re-make the bare board but use higher quality dielectric and thicker copper.

and then they can desolder each and every component from the original and transplant it to the newly etched board.

that will keep em busy for a good long time and off the forums with silly questions

Well, excuse me maybe I shouldn't, ask any more questions here please forgive me Geez! 

[I_may_be_drunk_right_now]

Hey guys.  No magic here.  I go through these units and test electrolytics for problems with value and ESR, both of which can have an effect on low frequency response and decoupling/crosstalk.  You would not believe how many big power supply electrolytics I find that are so dry they sound like a can of pennies when you shake them (and the amp was still working at the reduced capacitance).  You bet replacing them improves the sound and power output.
I am definitely not a believer in esoteric cables, mysterious magnets, etc.  I quantify problems and solve them.

There is an excellent book on audio power supplies, among other subjects, but it's only in French AFAIK.

http://www.amazon.fr/Bien-Entendu-itin%C3%A9raire-audiophile-%C3%A9dition/dp/2866611616

I'm always amazed by people who think that nothing has an effect on sound, it's almost as if they think that by denying everything they're somehow more rational.

It's like scotch, I used to think they're all the same but obviously not, and very obviously there are massive differences in sound quality and it's nothing to do with voodoo.

[dannyf]

I'm always amazed by people who think that nothing has an effect on sound,

I'm always amazed by people who understand the discussion to be like that.

Many things can have an effect on sound: speakers for example have a huge impact on sound reproduction.

Then there are things that are unlikely to have much impact on sound: can you hear that amplifier's feet? or electricity from a hydro plant vs. a coal fire plant? Or made-in-Japan 5200 vs. made-in-the-US 5200? silver solder vs. regulator solder? regulator cable vs. bi-directional cable? ...

The list goes on. Now, if you can indeed pass a properly administered double blind test, I may rethink.

[dannyf]

Here is one of many online listening test: http://www.klippel.de/listeningtest/lt/

Try it and see how good your hearing is. Then check that vs. your amp's specifications,

[rdl]

I thought the original question about replacing electrolytic capacitors in a 25 year old piece of electronic gear was perfectly reasonable. Yet several responses were completely irrelevant and not very useful.
 

[sarm]

-18 dB in my test.
What does it means in practice ?

[calexanian]

i think we should try to convincen the audiophile community to upgrade the circuit boards instead.
like re-make the bare board but use higher quality dielectric and thicker copper.

and then they can desolder each and every component from the original and transplant it to the newly etched board.

that will keep em busy for a good long time and off the forums with silly questions

And if they use RA flux solder and leave the flux on it gets that "Silky Sound"   thats part of the mojo right? And those gold plated pads really helps a lot! And don't forget your silver wire.

  

[ampdoctor]

Audio grade capacitors; As somebody once said, an audio-fool and his money are soon parted!

Those big ass e-lytics have the worst tolerance of any component in the product, except maybe output transformers. Even that's iffy! If you're hell bent on replacing capacitors, you'd be well served to just use something on the order of 5000hr or greater 105c low ESR caps. Also given the choice use smaller diameter caps in preference to larger diameter, i.e., 22mm snap in's are preferred over 35mm. As somebody else said elsewhere in this thread, Panasonic makes some VERY good caps with these ratings and they're a fraction of the cost of "audio grade" caps. Anything else is just marketing bullshit.

As an aside, you absolutely need to use silver wire! The last thing you want are a bunch of vampires and werewolves getting into your equipment and mucking things up.

[Fsck]

-18 dB in my test.
What does it means in practice ?

-33 dB for me = 2.238%

[SteveyG]

I thought the original question about replacing electrolytic capacitors in a 25 year old piece of electronic gear was perfectly reasonable. Yet several responses were completely irrelevant and not very useful.
 

It is perfectly reasonable. It seems some people have an issue towards people who don't want to hear mains hum and other artefacts 

[p5200]

I thought the original question about replacing electrolytic capacitors in a 25 year old piece of electronic gear was perfectly reasonable. Yet several responses were completely irrelevant and not very useful.
 

You are right! all I did was ask a simple question and I get such childishness from quite a few who, I assume must be followers NOT! leaders. But, I do appreciate all the sincere help from those who treated me with the same respect I have since I joined this forum. All I can say is no wonder, there is so much child bulling going on these days. But, I will try to bite my tongue it's pretty bad when a man in poor health unable to do much of anything anymore tries to do things to take his mind off of things and get taunted this way. I am not, in competition with anyone my skills in electronics are very limited. But, if you folks who like to bully want some real competition about audio, Google the name John Curl the famous designer/ consultant in audio design and much more contact him and you might just find yourselves eating some crow. Is there any moderators around? or should I just quit being so nice as these very insulting people don't realize and probably don't care, they are picking on a man who is half dead anyway and has nothing, to loose?