When is used used up?

When repair costs exceed market value?
When repair costs exceed nostalgia value?
When you decide to replace?

Depends on the gear.
I have a 1961 Bell tubed integrated amplifier with the original RCA 6v6 and Telefunken tubes.

I have owned it for almost 5 years, and don't play it much, but I've never had a problem.
As far as how many owners and how much use it has had I am not aware of, only that all the insides are stock, and no mods.

Everytime I take it out and insert it into my main system, it works,perhaps I am just lucky and it's on borrowed time.

The strange thing is, this unit isn't too far off the mark from some of my more expensive gear and certainly not tubey sounding or rolled off and distorted like some of the 1970's solid state receivers I have heard.

That being said,I just don't understand how gear from the 1970's that was mid fi, mediocre, seems to have taken on cult status and is referred to as Vintage and demands big bucks.

To me it's just old, it wasn't great then, how could time have improved it?
So to me if it works, you like it, got it for peanuts, then congrats, but when it needs fixin, it's useful time is up.

Kijanki is correct - the operating parameters of electrolytic caps are constantly degrading primarily from heat. While the actual capacitance figure in microfarads may remain fairly stable, ESR, dielectric absorption and leakage current are constantly degrading from use. Unfortunately, without something like a Sencore capacitance analyzer, these parameters are difficult to check. Electrolytic caps with any type of case deformation (bulges, etc), or white residue around the rubber gasket at the base is overdue for replacement.

Norman - Not likely to find White Papers on basic stuff like that.

Amp's output current flows from power supply capacitor thru it's Equivalent Series Resistance (ESR) and Equivalent Series Inductance (ESL) then thru output transistors and speaker to come back to power supply capacitor.

Amplifier attempts to regulate/mantain required voltage level but power supply cap's ESL will make it less than perfect at higher frequencies while it's ESR if high enough will cause high voltage drops and eventually amp will run short of voltage.

ESR of capacitor is constantly increasing because of drying effect up to point that after long time self heating (big current x ESR) will cause thermal runaway effect (ESR increases with temperature) and capacitor might even explode. To prevent catastrophic explosion all larger electrolytic caps have built-in fuse (rubber plug).

Quality of sound depends on quality of power supply caps (ESL, ESR, leakage etc). Best caps have extremely low ESR and ESL. Sometimes people bypass electrolytic caps with much lower inductance film caps (to speed-up response) but this creates parallel resonance circuit with ESL (and therefore ringing).

"Power supply capacitor is in series with a speaker (circuit closes thru power supply) and any increase in ESR will show as worse bass control (lower DF) and loss of dynamics."

I would love to read the white paper on this.. if you have one please let me know. Yes, caps can dry out and when they do the short or fail. Until the point of failure, it is my understanding that they are performing/suppling necessary and proper capacitance and therefore should have no adverse effect on the circuit.

Norman

"Capacitors do NOT DEGRADE over time, they FAIL."

- I don't know where you got this from, but even capacitor manufacturers admit that electrolytic capacitors dry out (and rate them). At room temperature they will last for 30-50 years but temperature accelerates process greatly (each 10degC cuts life by 50%). ESR of capacitor increases over time and, in presence of big currents, causes internal self heating (just few degrees) and so forth.

Power supply capacitor is in series with a speaker (circuit closes thru power supply) and any increase in ESR will show as worse bass control (lower DF) and loss of dynamics. We get slowly used to "new sound" but difference after replacement can be huge.

There are electrolytic caps that are better quality, lower ESR, lower inductance (like slit foil caps) and higher temperature ratings but they are expensive. Better (high end)manufacturers most likely use better parts.

I have owned many old mac amps, and when I acquire them, I send them to Mac for general servicing. I have NEVER had them do anymore than replace a burned out lamp. Ever! And I am talking about amps and preamps that were 15 to 30plus years old. Each one met spec. The same is true when I bought my harman kardon Citation 17 preamp and 16A amplifier. I sent them to hk on Long Island and they sent them back with a data sheet. They far exceeded factory specifications. It erks me a little when someone says 'oh I replaced the caps in this or that and now the unit sounds awesome' (caps are so easy to change and this seems to be the rage today) Capacitors do NOT DEGRADE over time, they FAIL. Which means if your amp is playing, your caps are fine.

So, I think that if a unit was manufactured using quality parts, you should be ok, at least that has been my experience.
Norman

When its FRIED!!

Hi Kijanki,

Thanks for mentioning those things, but yes in my case I have absolutely always done that. During the 1990's I invested in an earlier version of this variable ac power supply.

It provides a variac-type function that allows me to bring up the voltage slowly, while providing an ac current meter as well as a voltmeter.

My standard practice is to bring up the voltage over a period of about 8 hours, rather than several days, and that seems to have worked well for me generally.

The 50 capacitors that I mentioned I had to replace on one of the Scott's, btw, were all coupling caps, not electrolytics. I have, of course, had to replace electrolytics in other pieces of vintage equipment.

Best regards,
-- Al

Al - Do you remember to increase line voltage slowly over few days? Voltage re-builds up isolating layer of aluminum oxide in electrolytic caps, that tends to get thinner without voltage lowering breakdown voltage.

"Thrown away generally means gave away to a Goodwill""

hehehheheh.. Hate to break your heart, but the GW tosses most of that stuff too. Trust me, they have one down the street, and I have seen tons of used stuff tossed in the dumpster.

When you can no longer get parts for it, do not buy it.

Concerning purely electronic components (as opposed to electromechanical ones), my experience has been that, as Elizabeth said, it's a tough call. And it is very unpredictable, even when environment and usage history are taken into account.

During the 1990's I owned examples of a lot of the better vintage amps, preamps, and tuners from the 1950's and 60's. Some of them worked spectacularly well, some of them just didn't sound right, some of them had minor problems that I easily fixed, and some of them had problems that I either could not fix or chose not to fix, so as not to ruin originality.

Capacitors seem to be a major variable, as a function of the particular brand and year of manufacture as well as the usage history. I am not aware, though, of any comprehensive summary of which were the good ones, which were the bad ones, etc.

I've had very good luck with a number of FM tuners of the 1950's and 60's, even though a tuner figures to be more critical than an amp or preamp due to misalignment that can occur over time due to drift in component values. In my main system I presently use an all-original 1954 REL Precedent tuner, which works spectacularly well in terms of both sound quality and station-getting ability (except for some days when an intermittent problem appears, that I haven't been able to resolve).

I also collect antique radios. I have an elaborate two-chassis E. H. Scott console from 1932, which I believe is completely original including even the tubes (including a pair of push-pull 45's in the output stage :)). It also works spectacularly well in terms of both sound quality (AM only, of course) and station-getting ability. However, on a higher-end E. H. Scott model from 1940 that I also have I had to replace approximately 50 capacitors, some of which went up in puffs of smoke.

Both the good-performing 1932 model and the problematic 1940 model, btw, spent all of their years in the same geographical area, here in Connecticut.

And I am aware of several instances in recent years, involving high-end professional video equipment and also computer equipment, in which bad runs of capacitors resulted in a rash of failures after just a few years.

So it is a tough and unpredictable call. But my experience suggests that in the better scenarios older electronics can continue to perform well for far longer than might be expected.

Regards,
-- Al

TVAD-- I defer to the responses of Elizabeth and Stevecham.

Players with motors can wear out, like turntables and CD players. Plus, CD players have lasers that, like light bulbs, eventually burn out and need replacement. Electrolytic caps in amplifiers can dry out, though modern ones are much better than in days of old. The key to these is if they have been kept in use so as retain their form; amps which have been stored a long time without use are more prone to cap problems than are those that have seen regular use so I always check on this point. Resistors can drift off value, zener diodes can crap out. Speakers are a mixed bunch; I've heard 40 year old speakers that sound fine, their cones and surrounds are still intact. I have also experienced a complete dust bowl blow out when a ten year old speaker was fired up that was working fine a day ago. Perhaps cables are more dependable components simply because they have the fewer "moving parts."

How's that analogy work for us humans?? Same/same I guess. I personally know I have been out in the sun,way long.

Liz, good thoughts on environmental factors. I did not include the question molecular decay of components and connections which is a factor of the quality of construction also. So, I guess we have -- where used, how much use, and what is it.

All I can say Elizabeth, is you really seem to be in the know. Hats off to you! I learn something new here almost every day.