Audio grade capacitors question - Page 1
Forum section: electronics / projects

author: p5200
author_rank: Contributor
timestamp: February 24, 2014, 06:00:55 pm
content: 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!

author: c4757p
author_rank: Super Contributor
timestamp: February 24, 2014, 06:07:14 pm
content: Quote from: p5200 on February 24, 2014, 06:00:55 pmAny reason to believe they're actually bad? 1989 wasn't that long ago...

author: p5200
author_rank: Contributor
timestamp: February 24, 2014, 06:18:05 pm
content: 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!

author: don.r
author_rank: Frequent Contributor
timestamp: February 24, 2014, 06:29:32 pm
content: 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.

author: rdl
author_rank: Super Contributor
timestamp: February 24, 2014, 06:31:24 pm
content: 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

author: p5200
author_rank: Contributor
timestamp: February 24, 2014, 06:35:09 pm
content: Quote from: don.r on February 24, 2014, 06:29:32 pmThis one runs pretty warm since it is pure class A.

author: p5200
author_rank: Contributor
timestamp: February 24, 2014, 06:36:22 pm
content: Quote from: rdl on February 24, 2014, 06:31:24 pmI'll check those out.

author: commongrounder
author_rank: Frequent Contributor
timestamp: February 24, 2014, 06:41:13 pm
content: 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.

author: c4757p
author_rank: Super Contributor
timestamp: February 24, 2014, 06:46:23 pm
content: Quote from: commongrounder on February 24, 2014, 06:41:13 pmFreshening up the power supply capacitors improves the sound quality?I suppose, if it wasn't working at all...

author: Phaedrus
author_rank: Frequent Contributor
timestamp: February 24, 2014, 06:50:29 pm
content: 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!!!

author: free_electron
author_rank: Super Contributor
timestamp: February 24, 2014, 06:54:02 pm
content: 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

author: commongrounder
author_rank: Frequent Contributor
timestamp: February 24, 2014, 08:20:15 pm
content: 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.

author: SeanB
author_rank: Super Contributor
timestamp: February 24, 2014, 08:26:09 pm
content: 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.

author: Conrad Hoffman
author_rank: Super Contributor
timestamp: February 24, 2014, 09:54:24 pm
content: 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.

author: p5200
author_rank: Contributor
timestamp: February 24, 2014, 11:14:22 pm
content: Quote from: free_electron on February 24, 2014, 06:54:02 pmWell, excuse me maybe I shouldn't, ask any more questions here please forgive me Geez!

author: I_may_be_drunk_right_now
author_rank: Contributor
timestamp: February 24, 2014, 11:22:05 pm
content: Quote from: commongrounder on February 24, 2014, 08:20:15 pmThere 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/2866611616I'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.

author: dannyf
author_rank: Super Contributor
timestamp: February 25, 2014, 01:03:17 am
content: QuoteI'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.

author: dannyf
author_rank: Super Contributor
timestamp: February 25, 2014, 01:13:11 am
content: 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,

author: rdl
author_rank: Super Contributor
timestamp: February 25, 2014, 02:16:02 am
content: I thought the original question about replacingelectrolytic capacitorsin a25 year oldpiece of electronic gear was perfectly reasonable. Yet several responses were completely irrelevant and not very useful.

author: sarm
author_rank: Contributor
timestamp: February 25, 2014, 03:07:31 am
content: -18 dB in my test.What does it means in practice ?

author: calexanian
author_rank: Super Contributor
timestamp: February 25, 2014, 04:04:54 am
content: Quote from: free_electron on February 24, 2014, 06:54:02 pmAnd 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.

author: ampdoctor
author_rank: Frequent Contributor
timestamp: February 25, 2014, 04:35:34 am
content: 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.

author: Fsck
author_rank: Super Contributor
timestamp: February 25, 2014, 05:33:02 am
content: Quote from: sarm on February 25, 2014, 03:07:31 am-33 dB for me = 2.238%

author: SteveyG
author_rank: Unknown
timestamp: February 25, 2014, 10:20:18 am
content: Quote from: rdl on February 25, 2014, 02:16:02 amIt is perfectly reasonable. It seems some people have an issue towards people who don't want to hear mains hum and other artefacts

author: p5200
author_rank: Contributor
timestamp: February 25, 2014, 11:23:25 am
content: Quote from: rdl on February 25, 2014, 02:16:02 amYou 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?

author: dannyf
author_rank: Super Contributor
timestamp: February 25, 2014, 11:54:13 am
content: I am about -18db as well (around 10% distortion), vs. a typical amp of 0.x% distortion.

author: dannyf
author_rank: Super Contributor
timestamp: February 25, 2014, 12:01:24 pm
content: QuoteYou are taking it too seriously.You have to remember that this is a public forum free of any bias regarding the poster's health status, nationality, language, etc. - because we simply have no way of knowing that unless offered. You are getting the most objective view on a topic (and sometimes more). In this particular case, people are simply pointing out for you that there is no/low technical merits in your thinking, and/or replacing the caps unless you have found them to be defective. People are criticizing your approach, rather than you the person.Now, that may not be what you want to hear; or you may have perfectly rationale reasons to do it regardless.I am out of here.But it is in my view quite childish to project a level of ill intention onto people who were trying to help you.

author: ConKbot
author_rank: Super Contributor
timestamp: February 25, 2014, 12:02:46 pm
content: Quote from: rdl on February 25, 2014, 02:16:02 am+1Its not like the original post is asking for the best alternative for black gate or paper in oil capacitors. There are tons of different series of electrolytic capacitors available from different manufacturers, and the TS is just asking for which modern series of capacitor would be equivalent, and specifying the application so people might know which qualities are important.I'm as anti-audiophoolery as the next, but as a class A pre-amp, its drawing a constant amount of current, (100% full load) so the caps have been having to supply current ripple of 100% load for 25 years, I'd be more surprised if they werent degraded, and the main DC rails had more 100/120hz noise on them than when it was brand new. So unless someone has a schematic and knows the current draw and ripple figures and can say "Oh they are running at 10% max ripple they should still be fine" who is to say that replacement is unwarranted? And given that PSRR is fixed thats a direct measurable effect on the output. And even better is that 1% distortion while unquestionably audible on an amp output is beyond what an 8-bit DSO would be able to measure to any amount of certainty.If the TS has a scope and can measure ripple on the DC rails before and after changing caps, and if there is a measurable decrease in ripple, I'd say he has good footing to tell all the anti-audiophool-phools in this thread to piss up a rope. If not, its still a 25 year old electrolytic, if the amp is of value to the TS, then why not do a little preventative work to keep from having to deal with a failed cap later.Lord help this man if he asks for the best gold plated RCA connectors which fit in the factory footprint because he wants to replace old ones which have the gold worn off or something

author: p5200
author_rank: Contributor
timestamp: February 25, 2014, 12:11:59 pm
content: Quote from: ConKbot on February 25, 2014, 12:02:46 pmI know what you mean about Black gate capsI looked them up once just once, and about fell out of my chair at the pricesI don't have a scope nor do I even know how to use one but, I bet they are very interesting to use.

author: SteveyG
author_rank: Unknown
timestamp: February 25, 2014, 02:29:51 pm
content: Quote from: ConKbot on February 25, 2014, 12:02:46 pmThank you. Some sanity in this thread

author: don.r
author_rank: Frequent Contributor
timestamp: February 25, 2014, 03:18:23 pm
content: There is a tendency to jump on people when audio is mentioned because of the lack of objectivity in the field. I don't think the OP brought up any of the usual red flags like PRaT or "warmth". Since the unit is running Class A then, yeah, the caps are probably due for a swap. If you have the whole board out and swapping other parts then why not? Save yourself a return trip.

author: edavid
author_rank: Super Contributor
timestamp: February 25, 2014, 04:01:26 pm
content: Quote from: p5200 on February 25, 2014, 11:23:25 amIt's not at all a simple question. There is a lot of controversy about preventative recapping vs. replacing bad caps, and mixing it up with audio only adds to that.

author: dexters_lab
author_rank: Unknown
timestamp: February 26, 2014, 09:19:37 am
content: i cant believe that this thread where someone was just asking for a recommendation on equivalent cap models has turned into this!Why should the OP be judged in this way when just asked a simple question... maybe they have been asked by the amps owner to replace the caps, maybe the amp is a complete bitch to take to bits so its a convenient time to replace them? Or a whole host of other reasons!maybe the original caps are fine, maybe they are not... it's not for us to judge on here either way

author: SteveyG
author_rank: Unknown
timestamp: February 26, 2014, 11:37:02 am
content: Quote from: Dawgie on February 26, 2014, 09:23:28 amIt's a standard marking on capacitors...

author: Lightages
author_rank: Unknown
timestamp: February 26, 2014, 05:42:03 pm
content: P5200You asked a sensible and good question. Replacing caps of that vintage is probably a good thing but not 100% necessary unless you see what Conrad said. Follow his advice as Conrad is an entirely pragmatic and practical person without agenda. The people jumping on your question either misunderstood your intent or were just trying to be cool and with the crowd of anti-audiophoolery. Please don't get discouraged, there is always noise in the signal on the internet.

author: Lightages
author_rank: Unknown
timestamp: February 26, 2014, 06:07:11 pm
content: Quote from: dannyf on February 25, 2014, 01:13:11 amFor the record I tested -36db or around 1.5%. I did not find the test audio I selected (T Chapman) to be that dynamic or full range enough to show the distortion very well. The ear will be more sensitive to distortion under different conditions or sonic content. But this does go to show the real world sensitivity to distortion. It has been said many many many times in the audio world that generally any distortion below 1% is going to be unheard unless specific test tones or certain types of sounds are used. It has also been said that below 0.1% there is no perceived improvement.

author: Conrad Hoffman
author_rank: Super Contributor
timestamp: February 28, 2014, 01:21:29 am
content: Quote from: Lightages on February 26, 2014, 05:42:03 pmHa! And I have a halo and only sink 97% as deep as most people when walking through water. How dare you say I don't have an agenda- it's around here somewhere and I'll hold it up as soon as I find it.So much depends on the equipment plus a little bit of luck, good or bad. I've repaired things that should have been in great health, yet every single aluminum electrolytic cap was bad. Then I get some ancient guitar amp from the '50s and every cap is good. Much of my test equipment is classic stuff from the '50s on, and the number of bad caps and other problems has been minimal. Not zero, but nothing has needed a total rebuild either. For a while my agenda was to get people to measure parts and then replace the sick and tired. I gave up. That just isn't going to happen. Without measurement, there is only doubt, and the only sensible path is replacement. Unfortunately, with that option there's much chance of collateral damage, and parts that truly replace some of the old weird-aspect axials just aren't available anymore. BTW, of all the equipment I've serviced, I've never had a return due to a cap that subsequently went bad after measuring good for value and loss. Caps certainly go bad, and the odds of a problem go up with age. For consumer audio stuff, at 30 years one might think about a recap. At 40 years a couple bad parts are entirely expected.

author: true
author_rank: Frequent Contributor
timestamp: February 28, 2014, 02:20:19 am
content: Quote from: dannyf on February 25, 2014, 01:13:11 amInteresting, but there is absolutely no reason this should require Silverlight.

author: Jay_Diddy_B
author_rank: Super Contributor
timestamp: February 28, 2014, 04:34:21 am
content: Hi group,To get back to the original question, 'Should I change the capacitor in a 35 year old amplifier and what should I change them with?'Forget about this being Audio grade.It is quite possible that the original capacitors are good.You might still want to change them as a preventive measure. You don't want the capacitors to leak in the future and spill the electrolyte on the board.So what do you change them with?I would go to a website like Digikey where you can sort the capacitors by value, voltage, pin spacing etc.I would select in-stock.Then search for the physical size. I would allow voltages a couple of steps higher than the original capacitors. This because capacitors have become smaller over the years.I found CAP ALUM 470UF 50V 20% RADIAL UHE1H471MHD3 Digikey 493-1615-ND for the 470uF 35V partandCAP ALUM 1000UF 50V 20% RADIAL UHE1H102MHD6 Digikey 493-1622-ND for the 1000uF 25V part.I am not audiophile, so I am not sure if these the Nichicon HE series have any special audio properties. As an engineer with 30+ years of power supply design experience, these are very quality capacitors from a reputable manufacturer and I would not hesitate to use these in a power supply.Jay_Diddy_B

author: Lightages
author_rank: Unknown
timestamp: February 28, 2014, 04:55:48 am
content: Quote from: Conrad Hoffman on February 28, 2014, 01:21:29 amWell I meant you had no agenda in this thread. For all I know you fondle high precision resistors all night and search for rejects in dumpsters outside of Vishay just to give them a good home and a square meal.

author: Jay_Diddy_B
author_rank: Super Contributor
timestamp: February 28, 2014, 01:40:38 pm
content: Quote from: 3roomlab on February 28, 2014, 10:55:35 amProbably not. The ESR is a function of the age of the capacitor and the operating temperature. Even if they were balanced when new they would quickly drift apart. Film capacitor make a lot more sense for these applications.Jay_Diddy_B

author: Conrad Hoffman
author_rank: Super Contributor
timestamp: February 28, 2014, 03:14:09 pm
content: High frequency ESR is mostly a factor in switching power supplies. For power supplies at 50/60 Hz it isn't much of a factor in any aluminum electrolytic that's within spec, especially since audio equipment almost never runs a continuously high current. I suppose it would matter with a big class A amp.For coupling caps it shouldn't make much difference because circuit impedances are high compared to any reasonable ESR. Still, I prefer lower rather than higher values. OTOH, I'm also wary of caps that are optimized for ultra-low ESR because other properties may have been traded off to get there. For example, I have some ultra-low ESR caps designed for switching use, and they're very good, but they tend to have higher DC leakage than most other caps. I bought some very long life 105C caps that were aimed at the LED lighting market. They're very good too, but they have slightly higher ESR than I would have expected. Thus, I tend to go with more general purpose series, well established part numbers and only with brands having a proven track record.There are only a couple places in the signal circuitry itself where you need values so high that you can't use film. The only places that quickly come to mind are ac coupling a feedback divider and emitter resistor bypass caps. If you need a big coupling cap, use a large enough value that essentially zero audio voltage appears across it. If no voltage appears across it, it can't affect the signal.

author: markce
author_rank: Regular Contributor
timestamp: February 28, 2014, 11:37:02 pm
content: @don.r+1Very strange response from some people as soon as the word 'audio' is in the posting title.I also know there are a lots of people selling snake oil for better audio performance.But why not seriously design components for audio use. It's done and with good results...For and old amp of good design and economic value, and if you are pretty sure the cap's had most of their lifetime,replace them all with cap's that have known sound quality.

author: ampdoctor
author_rank: Frequent Contributor
timestamp: March 01, 2014, 05:46:15 am
content: After 35 years I'd replace em on general principle. They may not be bad but they've definitely seen better days and are most likely running beyond their designed lifespan. They're not really very expensive components and you'll save yourself the aggravation of having to go back in and replace them a few years from now when they do go tits up.As for brands and types/series, that was already covered earlier in the the thread so no need to go over that again.

author: linux-works
author_rank: Super Contributor
timestamp: March 01, 2014, 04:56:54 pm
content: Quote from: c4757p on February 24, 2014, 06:46:23 pma LOT of audio guys believe the quality of the PSU matters a lot.if you think about it, what are you doing by amplifying? you are essentially taking a power supply and modulating its output. so the control signal is not really the signal you get out, you are getting the power supply's output. if the power supply is less clean then your output signal will also be less clean.and if you think that analog circuits are the only ones affected, the digital guys go nuts trying to get better and better psu's for their dac, i2s and spdif systems.I like to have a 'competant' psu but I don't go overboard like some audio nuts do.as for caps, I prefer pany FM and the newer FR series. just because they are a known quality part and if you buy from real vendors, you won't get fakes.

author: don.r
author_rank: Frequent Contributor
timestamp: March 01, 2014, 05:21:30 pm
content: PSRRIs there such a thing as "audio grade"? No. All there is are parts that meet or exceed the requirements of the circuit. Some parts are better in some desings than others.

author: Zero999
author_rank: Super Contributor
timestamp: March 01, 2014, 06:50:40 pm
content: Quote from: linux-works on March 01, 2014, 04:56:54 pmIt doesn't though. If the amplifier is properly designed with a high gain and lots of negative feedback, it should have a high power supply rejection so a fluctuation in the supply voltage won't be transferred to the output.It can become a problem though if a switched mode power supply is used without good enough filtering of the higher frequencies which can be demodulated by the amplifier and cause noise on the output.

author: commongrounder
author_rank: Frequent Contributor
timestamp: March 01, 2014, 08:01:25 pm
content: Quote from: Hero999 on March 01, 2014, 06:50:40 pmRight. But if the main filter caps in an amplifier power supply lose value, they may still filter the DC, but under load the amplifier will clip sooner, i.e. less output power, because of the deeper ripple. That, in my opinion affects the sound of the amp. My quote was also taken out of context ("freshening up") , as I was mainly referring to caps in the audio signal path. One other parameter that hasn't been mentioned but is a big problem with older caps is leakage. Often electrolytics in the signal path do not have a lot of DC bias on them, and can get leaky causing all kinds of problems with switches and potentiometers, not to mention affecting circuit operation. That is reason enough to swap them out when any one of them measures poorly in that regard. If one does, it is likely the others, especially the same brand or value, will be, or go, bad soon. This is just my experience repairing this type of gear.

author: linux-works
author_rank: Super Contributor
timestamp: March 01, 2014, 08:13:00 pm
content: a lot of 'properly designed' (discrete) amps don't have the psrr that many op-amps have.also, class-a amps put a steady load on the psu and so speed in the psu does not matter. non-class A amps may put varying loads on the psu and speed to maintain the output voltage does matter.

author: p5200
author_rank: Contributor
timestamp: March 02, 2014, 12:56:06 pm
content: Quote from: Jay_Diddy_B on February 28, 2014, 04:34:21 amThanks very much for searching for those partsI will look into them. Unfortunately, my power amp is on the blink again. Talk about VooDoo, it has an electronic on/off power button and the other night it decided to leave standby mode and turn it's self on.then I couldn't turn it off with the power button had to unplug I won't go into it any further in this thread as it really doesn't belong.