Symtoms of bad caps???

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Altecfan

Banned
2016-01-14 7:24 am
I was wondering how much bad caps can deteriorate sound especially high frequency.My amp and preamp are 16 years old now and while listening to a test record i could not hear past 11000khz so i switched to a test cd and could not hear past 11000khz. My speakers are Altec model 19's they extend enough to hear past 11000khz?
 
11000 Hz = 11 kHz
:eek:

That's very bad! Too many lowpass sections splitted into various stages
And also the cables to connect might show some R-C coupling

Nowadays when speaking digital the lowpass anti aliasing filter after the DAC is the first filter you'll encounter along the signal path; then there's the cable that connects to the preamplifier ( signal conditioning ); at the input of the amplifier you'll find an HF suppressor. Then the powered signal will find the HP filter on the tweeter path, being the tweeter itself a bandpass device having its high Ft point.

And nowadays that Ft could and should be past 20 kHz
 
I've been really careful with using earplugs since ROTC camp 1969, and my hearing rolls off at 14 khz; As tested by the service hired by my employer.
If you use a firearm, chainsaws, motorcycles, or gas lawnmowers, go to the wrong concerts without ear protection, welcome to the tin ear club.
I can't convince the "elders" at church that their $30000 yamaha sound system sound like dirt. The salesman told them how good it was. Too many "real men" in that group. At least wimpy musician me still has 14khz.
 

Eldam

Banned
2012-09-13 12:25 am
France
How ESR can be affected by aging ? Is it only the number hours of playback or is it also the years without playback (chemical Inside alum cap which is drying ?) !

If an amp is playing, let say, 10 hours per week : can you keep the aluminium caps more than 20 years ?

I noticed a softer treble with some amps being older... without knowing if it was my ears which were older in fact ! :D ! Less slam in the bass region a better indicator of old caps in amps ?:confused:
 
How ESR can be affected by aging ? Is it only the number hours of playback or is it also the years without playback (chemical Inside alum cap which is drying ?) !
If an amp is playing, let say, 10 hours per week : can you keep the aluminium caps more than 20 years ?
I noticed a softer treble with some amps being older... without knowing if it was my ears which were older in fact ! :D ! Less slam in the bass region a better indicator of old caps in amps ?:confused:
The bass tightness certainly has something to do with ESR in the mains caps. I use ZZ Top Afterburner CD as one test of speakers amp etc, marvelous bass drum hits. Bad ESR will show up as low maximum power(voltage) on a simple VOM with a known resistance (8 ohm) load.
Some amps had better sealant in caps than others. Allen and Rodgers S100 organ amps are just starting to show mains cap failure at 30 years of age, with the Allen having Sangamo 15000 uf ones. I caught a 1980 build S100 potting out 2 W/ch last October before mains cap replacement. It had gone silent in the middle of the previous service. Hammond organs started wimiping out before 18 years to go by the 1985 date caps in my professionally maintained 1967 H100 organ. My 1961 build dynakit ST70 amp was down to 7 W/ch in 1970 at the Macintosh clinic. with bad mains caps after 9 years the Mac salesman told me. From 1970 to 1985 I could get no better cap from TV repair supplies. The Sprague Atomlytics went bad in about 7 years @2000 hours/year, as proved by B+ voltage drop at attempted maximum power. Now we can buy 3000 and 5000 hour service life snap in caps, which I've installed in the sT70. There were epoxy sealed caps from both sprague and CDE as early as 1970. I've never seen any but a guitar amp repairman on organforum has seen some "green CDE's" . In good shape on the ESR meter, he said.
 
I am 58 and my ears hear up to about 10Khz.
One ear isn't quite as good as the other.
My right ear is slightly better.

I once went to a Status Quo concert in 1977 before laws came in about max sound level.
I couldn't hear for 3 days afterwards.
I have also run a mobile disco for about 30 years. During the vinyl period I mostly wore headphones which helped cut out some noise.
 

Ian Finch

Member
Paid Member
2010-04-11 4:22 am
Coffs Harbour, NSW
How ESR can be affected by aging ? Is it only the number hours of playback or is it also the years without playback (chemical Inside alum cap which is drying ?....
Here's a white paper - a technical guide to the ageing of capacitors, both polymer and wet electrolytic types. Life expectancy is predictable and minimum service life at max. rated conditions is specified for genuine components in any case. Read the data sheets and find out what's junk and what you may expect to last many years at your particular service conditions.
http://www.repeater-builder.com/tech-info/pdfs/replacing-capacitors-from-emerson-corp.pdf
 

Eldam

Banned
2012-09-13 12:25 am
France
Thank you very much Ian,

My main amp is a second Hand Chord SPM 1200 B , switching PS ! It deserves maybe a cap cure as it's an old 20 years device... I will read it carefully ! Btw I have tons of caps to measure (ESR) :) !

I checked also my ears as a good audiophile and music lover... damn I have a dig in one of my ear... I have a natural notch band pass butnot stereo yet :D
 
I read the white paper. The capacitors discussed are capacitors in UPS power supplies. They discuss the modificaion of the aluminum by power, they do not discuss the presence or absence of water. At the end a conclusion is reached that DC alumimum foil electrolytic capacitors rated 1000 to 12000 service should be replaced after 45000 to 50000 hours service, which is expected to be powered up 100% of the time..
This doesnlt relate to consumer grade audio equipment IMHO. No mention is made of the tendency of the water in the cap to evaporate out the fiber plug and elastomer seal even when sitting around un-powered. I've had consumer grade caps go to 40% of deliverable power in 7 years of 2000 hours a year service (sprague atomlytics from 1970) I had one cap I install run two hours, sit on the shelf 25 years until I bought new output tubes, run 2 more hours, then leak all over and blow the fuse (CDE cardboard tube multi gang cap bought 1985). Many purchasers of old organs on organforum buy one that hasn't been used in years, maybe 40 hours use since purchase, it works a week then goes silent or blows the fuse.
As the Allen S100 amp Sangamo mains caps "never fail" according to an organ repairman in Arkansas, and ours in Jeffersonville did after 35 years service, some caps are sealed better than others. A repairman in North Carolina on organforum says the sardine can crimp seal 2-4 uf caps in 1945-55 hammond tone cabinet amps read fine on ESR and capacitance at 50-55 years of age. He also says the "green CDE" epoxy sealed caps in some guitar amps are the same. So IMHO sealant has a lot to do with years life. Don't buy 500 hour service caps IMHO. I don't know if the 3000 to 10000 hour rated service life caps I'm installing now will last 35 year at low usage/year, but I hope to be here to find out.
There is another number, shelf life. I think this has to do with whether caps can be installed unpowered before they unform and might short at initial power up. I check all caps with an ohmmeter before I install them, which reforms them somewhat with 2 VDC.
And the people that think reforming is all you have to do to old caps, could also believe in fairies in the garden. Try checking the air pressure, then driving on 25 year old tires, for a reality check. 25 year old rubber is ****, and if the caps builder used that **** to seal your cap, the cap is pressure sealed with dirt after some years. That CDE cap blew with 4 hours service life on it, and 25 years.
Unless the part number is written on the cap (usually not) and the original datasheet from the year of purchase has been saved, you can't tell with an ESR meter whether the sealant was gum rubber, tar. buna N rubber , silicon rubber, epoxy. You can spot the steel crimp of 1945. End plugs can be fiberboard alumimum or steel. A better guide is, how do the caps purchased by this manufacturer generally hold up? In my experience, dynaco OEM and TV repair supply caps, 7 years @ 2000 hours power per year (hot location). Hammond and Wurlitzer organs built 1955-1980, 15-20 years, more in air conditioned houses and cool environments (Kent UK) . Allen & Rodgers organs, 30-50 years, the lower number in non 100% air conditioned churches in warm enviroments (as here). Peavey amps (2 samples), 15-20 years with weekend bar band use. (A 1998 amp is blowing the fuse unless powered up several times). Computer accessories and TV remotes, 5 years or less, Apex is the worst. Dell computer boards (intel) seem to last longer than gigabyte, and this Phillips CRT monitor is 15 years old, many lesser CRT monitors blew the fuse after 3 years. In motor drives, Semi brand motor drives leaked out the caps slime and blew the breaker after 3-5 years (CDE flat pack caps MLPE1192 to be specific). Semi drives are no longer used by that conveyor builder,. Woodman and Allen Bradley motor drives can go 10 years 24 hours/day 6 days a week in 130 degree F oven motor compartments, before blowing the end out the caps (nichicons were in woodman drives, AB drive caps are marked with their brand).
 
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Ian Finch

Member
Paid Member
2010-04-11 4:22 am
Coffs Harbour, NSW
I don't see the problem in knowing how your caps will deteriorate under controlled, standard conditions, though I have to agree that audio applications will be very different and introduce a lot of new variables. For home music listening, equipment that spends less than 5% of the time powered and then only at light duty, I'd say that the specification of most interest would be shelf life because typical 2,000 hr caps used in home audio gear, will usually last 15-20 years playing the occasional recording at a few watts and for occasional parties where the voltage peaks will possibly be clipping frequently. The fact that the caps are well below par by this time seems not to worry a lot of people but then I've seen amplifiers still being used even when the output transistors are blown :xeye:

For anyone who actually likes reading about caps and failures, this wiki on bad caps in PCs is informative and gives a few details of materials and construction of present-day parts that electronics texts never seem to discuss. Some comments on the formulation of some well known Japanese cap. types too: https://en.wikipedia.org/wiki/Capacitor_plague#Prevalence
The text could use some editing but there are some interesting references to follow up on, like this challenging little gem on the estimation of ELCAP lifetimes: http://jianghai-europe.com/wp-content/uploads/JIANGHAI_Elcap_Lifetime_-_Estimation_AAL.pdf
 
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