Choosing replacement capacitor's for computer stereo ? - Page 1
Forum section: electronics / beginners

author: MathWizard
author_rank: Super Contributor
timestamp: October 18, 2020, 10:59:57 pm
content: I'm ordering some stuff from Newark Canada, and so I'll add anything extra I need, onto this order. And I want to recap some of my PC stereo, that has other problems, but the new chips are on the way.What are some mid-range brand/model electrolytics to get for audio path caps that are2.2uF10uFmaybe a 47uF in the audio path too, icr470uFLooking at the prices, and datasheets, they don't even usually say an ESR, or what freq range response is like.I tested most all the electro caps on this with an LCR meter, quite a few were near bad or just over the limits.There's also a few 0603 SMD caps, like 1uF, that look like the common cheap SMD caps that are everywhere, so ceramic or multi-layer ceramic ? Aren't they bad for audio freq's? If they are tantelum's, they still look just like the cheap/most common SMD cap's. There's 2.2/3.3/4.7nF SMD caps, and 220p or 330pF too, in the op-amp frequency response chain.So for them, I just chose the same size and safe voltage rated multilayer ceramics, and actully the cheapest. Should I perhaps order more expensive of them too ?Being new to looking at the data sheets of caps, of the few I saw so far they don't even state the ESR.....seems pretty lazy, since most every time I check a cap, I check the ESR. I'm sort of aware of the Q factor and dissapation factor, although I never had a need to really calulate any of that yet.But soon I'll be learning more advanced capacitor models, so far I just used perfect caps, for any calulations I've wanted.

author: bob91343
author_rank: Super Contributor
timestamp: October 19, 2020, 04:22:15 am
content: Audio frequency operation has no special requirements. In fact, it's among the least critical places for components. I defy you to hear a difference when changing brands etc. as long as the component rating is correct.I realize this may annoy some who subscribe to the mythology of perfect sound reproduction but it's been proven again and again that there is nothing special here.So buy what's available and/or cheapest and be done with it.

author: Whales
author_rank: Super Contributor
timestamp: October 19, 2020, 08:22:31 am
content: I would recommend getting name-brand electrolytic caps over cheapies in order to obtain better component lifetimes. There are lists of common suppliers across the web, eg Rubycon Nichicon Chemicon. EDIT: usually the price differences are not too crazy.QuoteShort answer: this isunlikelyto be a notable source of distortion in the design, but itcouldbe.Spiritual answer: a capacitor on its own is neither good nor bad for audio freqs.Long answer: "it depends". If the Vswing from the audio signal is very small across these caps (eg mV) then they won't provide much in the way of distortion. Depending on the negative feedback circuit employed they might not even matter that much.QuoteYou probably want to read about the different ceramic capacitor chemistries. C0G, X7R, etc. Again I suspect these will not be the largest source of distortion in your amp, it's worth looking at other important parts (eg is there a monolithic all-in-one amplifier chip at the end?)QuoteUsually there is a big table that lists the ESRs for a variety of sizes? Maybe the caps you are looking at are too cheap to have any guarantees in their datasheet"Freq range response" depends on how you use the capacitor in a circuit. If it's in an RC filter with 1kohm or higher resistance: the ESR (often much much lower than 10ohms) probably doesn't matter at all. The other parasitics in the cap don't matter at these very low (ie audio) frequencies. There would probably be no use providing a freq response chart for your purposes, but if it is provided it will probably focus on 100's of KHz and above (where stuff you don't care about starts to matter).QuoteESR is not directly an indication of quality, but it is an indication of failure. ESR skyrockets when a capacitor dries out, but the differences in ESR between different (new) caps are not always important.Eg: imagine an expensive cap is 0.5ohms ESR and a cheaper one is 4ohms ESR. If these are used in feedback circuits on opamps (ie with resistors 1K and above) then the difference is negligible. If these are used in series with a speaker as DC blocking caps then the difference would be notable (as most speakers are only 4ohms or 8ohms).If you want to improve your amplifier: don't guess, measure. Use a scope with an FFT, or any equipment that can plot stuff with frequency as a horizontal axis, or even use another amplifier (probing different points in this circuit + listen to the signals). It's simply way too easy to convince yourself that it "now sounds better", there is a long history of research into perceptual acoustics and why you cannot trust yourself to be a judge unless the differences in distortion are absolutely huge. EDIT: worth reading around, eghttps://sound-au.com/articles/myths.htmlMathwizard:what is a "PC stereo"? Amplifier in a computer, amp+radio with lots of displays, ?

author: MathWizard
author_rank: Super Contributor
timestamp: October 19, 2020, 08:12:46 pm
content: Thanks for some info, it's an amp/reciever that drives 5.1 speakers.I had narrowed it down to Panasonic and another big name, Sony, if they make caps. But yeah I couldn't figure out which lines are for what, besisdes high power caps. So I guess any of them others should be fine then.I'm no audiophile, and this is a cheap system, I'll have to look a bit more at the SMD types

author: tooki
author_rank: Super Contributor
timestamp: October 19, 2020, 09:48:51 pm
content: Quote from: MathWizard on October 19, 2020, 08:12:46 pmI don’t know if Sony ever made caps. I’m reasonably familiar with late 80s and later Sony gear, and the only Sony components I’ve ever seen are ICs and image sensors. (And assemblies like CRTs and laser pickups.) So my hunch is that they never made passives, nor commodity ICs.For what it’s worth, Panasonic is my go-to brand for electrolytic capacitors, though I wouldn’t hesitate at all to use Nichicon, Chemi-Con, Kemet, Cornell Dubiloer, Rubycon, TDK, or Vishay — they’re just rarely cheaper than Panasonic, at least for the values I’ve needed. Panasonic has some really nice overview of their capacitor lines in their PDF catalogs, which tell you what each model adds compared to the cheaper neighbor. Very handy.