Retrovert
Addicted Member
I don't know what components you're looking at, but I suggest you look at how competitive the marketplace is and the corresponding improvements in specifications.
Nichicon audio grade caps....which to use
- Thread starter matt e.
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I don't know what components you're looking at, but I suggest you look at how competitive the marketplace is and the corresponding improvements in specifications.
Retrovert
Addicted Member
That's a large value for a coupling capacitor. I can't readily find a schematic to see why this was used.
Still, a PP film capacitor in that size is not so humongous it can't work. Cleaner sound and never needs replacement.
Oh, it was a very different time. Snubbers were about as good as anything thought of. Now a TRIAC and the support circuitry is so inexpensive who wouldn't use one? I will convert all of my gear to use them. For $5 never have to worry about a power switch going bad. I, instead, use socket strips but there is still the current through those switch contacts.
triode17
Super Member
I know why these caps. are small, they are polyester (aka Mylar). We audiophiles that design and build use polypropylene caps, which are larger but sound better.
BTW, electrolytic caps die more from non-use than expected hours of life. As sboa found, at 40 deg. C (typical temps.), caps are estimated to last for 70,000 hours. That's 8 years if used 24 hrs a day. So, i wouldn't worry too much. Its much ado about nothing, IMO.
Retrovert
Addicted Member
You omitted ripple current which will rapidly destroy power supply capacitors. It causes ohmic heating because of ESR which degrades or bakes out the electrolyte.
Beyond that, many power supplies miscalculate peak voltages for filter capacitors.
Other mistakes include narrow conduction angles which force charging into a short region which heats the plates and gradually ruins them.
Finally, many power supplies are continually on which dramatically shortens the lifespan.
Numerous technical papers have been written on the subject of reliability and failure for electrolytic capacitors. The audiophile lore on the subject is simply wrong.
triode17
Super Member
Retro - I believe he is talking about replacing 10 uF coupling caps on the preamp board. Not main filter caps. So ripple won't really come into play.
Retrovert
Addicted Member
I was responding to a general statement about electrolytic capacitors which wasn't qualified as to when used for coupling.
Furthermore, if an electrolytic coupling capacitor fails as a short it puts DC (B+ or rails) into the grid/base of the next stage, turning it fully on and usually causing a meltdown.
Electrolytics sound terrible in the signal path. No need to use them.
fred soop
Super Member
Coupling capacitor size is determined by the input impedance of the next stage. Read Small Signal Audio Design by Douglas Self. He has actually tested most of what he writes about and has tested electrolytics (and other capacitor types) in a simple RC circuit using a 47 µF capacitor and a 1K resistor with a 10 mV signal. At 20 Hz, distortion is approximately 0.01 %. Increasing the capacitor to 100 µF cuts the distortion to 0.002 % Increasing to 470 µF (10 times the original value) reduces distortion to the noise floor. Further increases result in no additional improvement. He concludes that the signal voltage across an electrolytic needs to be kept below 80 mV.
I have done simulations of various preamp stages using various values and looking at the frequency response. A good op amp design using lower value resistors for minimum noise contribution will need 22 µF to meet the 10 times over criteria. The coupling caps are usually not under stress and will generally fail open.
Ripple is an overlooked issue on main filter capacitors and few people even know about it or understand it. I was asking fellow engineers in our design group at Sperry Univac back in the 1980s and only one engineer even understood the problem but still didn't have any answers. He even had a masters degree. I initially became aware of it from some National Semiconductor literature.
I have done simulations of various preamp stages using various values and looking at the frequency response. A good op amp design using lower value resistors for minimum noise contribution will need 22 µF to meet the 10 times over criteria. The coupling caps are usually not under stress and will generally fail open.
Ripple is an overlooked issue on main filter capacitors and few people even know about it or understand it. I was asking fellow engineers in our design group at Sperry Univac back in the 1980s and only one engineer even understood the problem but still didn't have any answers. He even had a masters degree. I initially became aware of it from some National Semiconductor literature.
RE: 10uf 50v WIMA MKS2B051001N00JS
Heads up in case anyone is considering these:
I received my order and did not pay close attention to the details. The image in the catalog states it is for reference only. Had I read the datasheet thoroughly I would have noticed the leads for this part number are spaced 5mm apart and only 6mm long. So even though the size of the cap fits well the leads do not. Fortunately the kind people at Mouser ok'd my return so I'm not stuck with them.
Heads up in case anyone is considering these:
I received my order and did not pay close attention to the details. The image in the catalog states it is for reference only. Had I read the datasheet thoroughly I would have noticed the leads for this part number are spaced 5mm apart and only 6mm long. So even though the size of the cap fits well the leads do not. Fortunately the kind people at Mouser ok'd my return so I'm not stuck with them.
Wima MKS2 10µF/50v 5% cut-tape with ca 16mm long leads are PN 505-MKS2B051001N00JO00 at Mouser. (note that those last three positions in the part number are "oh-zero-zero".
Cheers,
James
Cheers,
James
Thanks for the cut-tape info and correct number. I'm going through the matching AJ15 tuner to complete another shopping list and will order the correct part next time
. Not intending to get off-subject, but I've been advised that Heathkit had some issues with the TO-3 sockets that lead to premature failure of the output transistors. I can see how the mica insulators, paste, and tightening torque could all be issues with kit builders. Not sure what could be wrong with the sockets, but for good measure I am replacing them. I suppose any old solid state amp should have the power transistors remounted after old age sets in. Found this pdf from Texas Inst regarding mounting considerations of TO-3 transistors that might be useful:
http://www.ti.com/lit/an/sboa020/sboa020.pdf
. Not intending to get off-subject, but I've been advised that Heathkit had some issues with the TO-3 sockets that lead to premature failure of the output transistors. I can see how the mica insulators, paste, and tightening torque could all be issues with kit builders. Not sure what could be wrong with the sockets, but for good measure I am replacing them. I suppose any old solid state amp should have the power transistors remounted after old age sets in. Found this pdf from Texas Inst regarding mounting considerations of TO-3 transistors that might be useful:http://www.ti.com/lit/an/sboa020/sboa020.pdf
fred soop
Super Member
Another note regarding capacitor replacement using some flavor of Nichicon: Most of the capacitors in the AA-15 are axial and most of the new ones are radial. There will be physical challenges to get them to fit. It may require splicing wire to one of the leads and laying them down flat. You might consider Vishay ASM series, one of the few axial lead caps still available.
Goldie99
Super Member
OTT, but thanks for the comment Fred - it just reminded me to check that series for some axials I need, and all I need are available from (UK) stock
KKnight
Active Member
Thats true about being powered on (in standby mode) 247, BUT THE MAIN REASON FOR FLAT SCREEN PS AND OTHER FAILURES IS THE FACT ALL MANUFACTURERS, REGARDLESS OF THE MSRP OF THE TV, USE THE ABSOLUTE WORST TIER 3 AND 4 ELECTROLYTIC CAPACITORS AT THE FACTORY LEVEL. Ive taken practically brand new flat screens, yanked the boards, and merely recapped them with Tier 1 'lytics and the results are almost amazing in terms of picture and tuning quality. Even some features that were barely noticeable like panoramic viewing excel after a recap with tier 1. As Ive said a 100 times before, the link should be a sticky: https://www.tomshardware.com/reviews/power-supplies-101,4193-5.html
sae-7125
Super Member
useful info on this aging thread. decades ago i noticed how one simple 5v sense cap on an antec power supply could render it useless. oddly enough thats where they put the cheapest component too, how so very self-destructive of them.
more useful info:
https://superuser.com/questions/1295722/how-are-capacitor-lifespans-measured-in-hours
more useful info:
https://superuser.com/questions/1295722/how-are-capacitor-lifespans-measured-in-hours
Some useful info indeed. You just need to separate fact from fantasy. For instance, recapping a flat screen TV will not affect the picture or tuning, even though the caps are cheap and will die prematurely in the power supply.
I wholeheartedly agree with @ChrisMarantz when he said:
The amplifiers THD has more to do with it's design than the components used in it. You will likely not have much difference in the final outcome by using one type of "audio grade" part over another. - Chris
Somehow capacitors have become an obsession in the audio world. There's far more to an amplifier or any other audio gear than just capacitors. Yes, electrolytic caps can and do fail with age. But replacing them with audio grade or any other caps that make unfounded claims just isn't going to make an audible difference, unless the original cap had deteriorated.
But at the end of the day, it's the owner's choice. If they think it makes a difference and it make them happy, that's another story.
Absolutely true. Capacitors are easy to spot and easy to change, hence the obsession with them on audio forums. You don't need to understand anything about electronics to swap a cap and get the "fantastic transformation in sound quality" that someone on a forum claimed they had.
sae-7125
Super Member
and yet, without capacitors (high capacity electrolytics) it would be difficult to discern music from rectifier ripple. the obsession between which high priced component will help squeeze out .01% better sound quality is a level of self inflicted insanity worthy of any dsm (diagnostic and statistical manual of mental disorders). especially since human hearing can be influenced by a common placebo effect, regardless of origin.
understanding something about electronics helps to avoid the following: change the standard 80v power filter cap with one rated for 25v just because the marketing said it was the best unobtainium in the universe.
i wonder what happens to amplifier thd when undersized caps are used (capacitance value)? something quite common in vintage gear due to the cost of early generation caps back then.
couple more capacitor links i bumped into:
http://www.audiotuning.de/index.html?2-01-blackgate-tech.html
https://www.humblehomemadehifi.com/Cap.html
understanding something about electronics helps to avoid the following: change the standard 80v power filter cap with one rated for 25v just because the marketing said it was the best unobtainium in the universe.
i wonder what happens to amplifier thd when undersized caps are used (capacitance value)? something quite common in vintage gear due to the cost of early generation caps back then.
couple more capacitor links i bumped into:
http://www.audiotuning.de/index.html?2-01-blackgate-tech.html
https://www.humblehomemadehifi.com/Cap.html
Seems that most will up the capacitance, not lower it. And with that comes other issues, like undue strain on power switch, power transformer and rectifiers.
First link was interesting due to graphs and other testing, stopped reading the second after seeing this:
The subjective results of this test
Just another guy telling you what "sounds" better. The human ear isn't up to this task, and the brain doesn't help here either, what with confirmation bias and other phenomena.
Here's a few links that I liked for their fact based and scientific reporting:
https://linearaudio.nl/cyril-batemans-capacitor-sound-articles
https://sound-au.com/articles/capacitors.htm
And I keep coming back to @ChrisMarantz and his statement:
The amplifiers THD has more to do with it's design than the components used in it. You will likely not have much difference in the final outcome by using one type of "audio grade" part over another. - Chris
Capacitors have taken an outsized role in the minds of those in the audio hobby. Yes, they can and do fail, and yes, electrolytic capacitors are one of the few electronic components that can die of old age. And yes, if you replace a bunch of dried out, failed capacitors with fresh new good capacitors you will probably notice a marked improvement. However, if you replace good capacitors with new capacitors you may think you hear an improvement. And finally, I need to say if it makes you happy please ignore this. I won't stand between anyone and their happiness... it's hard enough to come by in this life.