Refreshing Capacitors?

[DizRotus]

Please dont use this thread as a platform for a flame war regarding the relative merits of various types or brands of capacitors. My questions are general rather than specific. FWIW, Ive replaced the old stock caps in Heresies and La Scalas with new GEs from BEC and was pleased with the improvements.

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Intuitively it makes sense that the can capacitors used by Klipsch in its balancing networks will dry out, or otherwise go out of spec, after decades. Does the same thing happen to the various cylindrical capacitors with sealed plastic enclosures?

If capacitors in a crossover (any crossover) deteriorate over time, what effect would it have on the performance of the speaker? Would the bass get flabby, would the highs disappear, would the highs be exaggerated or would there be other evidence of capacitor degradation?

As a matter of course, would it make sense to replace the decades old capacitors in any old speaker? Even if they havent deteriorated over time, arent the newer types better?

Now youre free to express a preference for one brand of capacitor over another, but please dont attack those who express a preference for something that you dislike.

[Rotorhead09]

Neil,

good question... I just pick up a set of LS in my area. This guy purchase 6 of them back in the 80's. I was told he paid 550.00 a piece for them. I too was wondering if i needed to get the caps redone in them. They don't seem to have the punch like the other LS that I had my hands on. Just have no way to compare them now.

Santa

[Kriton]

Interesting question...I just so happen to have completed my cap

refresh this weekend on only ONE of a pair of otherwise identical Heresy I's,

albeit with E-2 crossovers...refinished and refurb'd one speaker and left the other completely stock.

I hooked them up last night and tried to AB them...with some initially

surprising results...the caps that I used in the refurb'd crossovers

were/are considered pretty good, I think...as opposed to the stock

crossover. The horns have not been doped, and I put several

different music sources through them...

What I think I heard initially, was greater detail - for instance, I

put in a clarinet concerto, and I couldn't hear the keys slap on the

fast passages on the refurb. that I don;t think I could ehar on the

older caps. The bass was however lacking a bit on the newer

crossover ---so frankly, I don't know what to think...

I too ahve wondered if the capacitors ony will deteriorate with USE not

necessarily over time...I think these Heresys were not used a whole

lot, from what I could tell form teh condition of the horns and what I

was told...so I am just not sure of the benefit that I am to see with

what is probably at least $50.00 in cap upgrades...per speaker. I

amm thinking I am going to keep them this way for a while, just to do

some more critcal listening, and then comparing these to brand new H2's

just for a lark.

I am going to be posting some picture later tonight, if the forum doesn't choke...

K

[Daddy Dee]

Interesting thread. I've been wondering the same thing about refreshing the crossovers in a pair of vintage Advent speakers.

Kriton,

Your results are most interesting. Don't know what to make of that. I don't even want to think that some caps get better with age. It is somewhat disconcerting to think that changing to new caps in the same crossover could diminish the quality of the sound.

Sometimes I think I might just throw in the towel get a nice Soundworks Model 12 portable speaker system... amp and sub included.

[BEC]

Generally, if the caps are 20 years old, they are bad. They will almost always read good on a capacitance tester at that age, but look pretty bad on ESR (Equivalent Series Resistance). ESR is the resistance equivalent of all the losses in the capacitor, or said another way, all the cumulative errors that make the capacitor function like something other than a capacitor. I usually see around 1 ohm of ESR in each of the caps from an original type AA crossover. The record I have seen is over 300 ohms.

In lightly used caps like those used in crossovers, I believe this increase in ESR is solely related to age with the amount of use playing almost no part.

Normally, after replacing the caps, the difference you hear should be mostly in the high end. In almost no case should the bass be effected at all since none of the Klipsch crossovers we typically rebuild has a series cap in the woofer circuit. A change heard in the bass is really a relationship change between the high end an low end with the high end being restored to where it should be.

Bob Crites

[Kriton]

Did I say that? Maybe I was unclear - my results so far just

indicate that the old caps weren't as bad as I expected, the difference

is there, just not dramatic at all...I don't think the old caps got

"better", they just don't sound comparatively very "bad"...and my

question is whether the deterioration is based on useage....I don;t

think the sounds dimished the quality, I am just not sure that it was

the bang for the buck I had hoped. I mean I used Thetas for the

2uf's and the big Solen for the woofer, that should be a pretty good

combo, no?

I mean it makes sense to me that a capacitor may deteriorate faster

when a signal is pushed through them for twenty seven years, don't you

think? If the speaker sits in a box unused for that whol eperiod

of time, do the capacitors have a shelf life? It was my

understanding that they lose "capacitance" as a result of time, not

use...but that was not really reflected in my listening last night.

I will try again over the next week...

K

[DizRotus]

Bob,<?xml:namespace prefix = o ns = "urn:schemas-microsoft-com:office:office" />

Your reply suggests that all capacitors deteriorate over time, is that true of the sealed plastic cylindrical variety as well as the Klipsch cans or GE motor-runs?

I deliberately avoided qualifying my perception that replacing the old stock caps in the Heresies and Las Scalas with your GE caps improved the sounds, as I didnt want to color the responses. As you indicated, the improvement was noticeable in the higher frequencies.

What prompted this question was curiosity over whether I should open up c. 70s LS3/5A clones to refresh the capacitors inside.

[3dzapper]

K, The E2 networks used those black box dry motor run caps. That could be why the difference isn't as large as with the older tin can type.

With the higher quality, made for audio, modern caps what will present is the increased detail. It will take a bit for the new caps to "break-in", maybe a hundred hours or more.Then is the time to compare again if that is your aim.

Bob, I am curious about any deterioration of the ESR on F&Fs too.

Rick

[BEC]

Rick,

Most of the caps that Klipsch used through the 70s, the ones that are in the AAs, are film and foil. The little black square caps plastic caps Klipsch used later vary from pretty good to terrible in an ESR test with most reading around 0.4 ohms and some up in the dozens of ohms. Seems like rather poor QC (by the cap maker) on those.

I really think that the newer type of oil filled can type caps will last a lot longer than previous types, but we have to wait for time to tell us that. What is sure is that if one of the motor run caps used in its normal environment got up to even 0.5 ohms ESR, there would be lots of smoke and fire. Therefore, I expect them to last a very long time before ESR becomes a problem in a crossover circuit.

Any new polyproplene cap should start out life with an ESR on the order of a few hundredths of an ohm. Any higher than that would indicate poor manufacturing techniques or materials.

Bob Crites

[Deang]

The Advent networks have electrolytics -- they should be changed out. If you want them to sound the same as they did -- use new electrolytics.

I don't know what kind of caps the Rogers LS3 used. All I know is that the woofer and crossover was supplied by KEF. Speakers of that style and vintage typically used electrolytics, though Mylars were not uncommon.

As for the longevity of axial wound polypropylenes: It would depend of the construction of the capacitor and conditions/environment exposed to over time.

Bruce, you detected a slight loss of bass response in the modded speaker. This is normal. You have "more" highs now, so you hear less bass. Do the other speaker and work with placement. It shouldn't take long to realize the across the board improvement in sound.

[DizRotus]

Thanks Bob and Dean. That was helpful.

[Kriton]

Sweeet.

Hey, the networks in my CW2's from BEC made them something else, I am expecting the same from these...

Thanks guys,

K

[Deang]

The caps in the original CII network are awful (sorry Klipsch). What did your E2's have in them before you changed them?

[Kriton]

Me? You mena the E-2's in my Heresy's?

The 2uf's were the two little square plastic buggers screwed to the

board, and the 33uf bass cap was the little inch and a half long black

Nippon can - same as BEC pointed out earlier...

Kept the same formers (obviously) -

Don't remember what were in the C2's I sent away, just don't remember...

What is really interesting is the side by side comparison of the 06

H2's sitting immediately next to the H1 with the refurb E-2

network...the sound is different and strangely so...I guess I need to

break in the caps first before making sweeping pronouncements, but it

is interesting none-the-less...

I want to tackle the crossovers on my beater H2's too (after completion

of this H1 project of course) - is it easier to replace caps on the

crossovers with the circuit boards????

I just realized that I have hi-jacked this thread, sorry ya'll...

K

[chops]

I guess I need to

break in the caps first before making sweeping pronouncements, but it

is interesting none-the-less...

K

Yes you do. When I replaced the caps in my Type B networks, I noticed that the upper midrange and the treble was pretty unpleasing sounding. They had a hard, unclean sound to them that I didn't like one bit.

After an hour had past running them in while I was cropping and resizing pictures of the upgrade process in Photoshop in the other room, I came back and sat down in front of the CWs. Just for that one hour of play time, everything seems to have calmed down some, certainly better than before. The CWs were still virgins at this point, so I was still running the Alnico K77s, which to my surprise had opened up considerably. The midrange also seemed a little "free-er" sounding as well. It was obvious that the 27 year old caps were shot and that the new GE's from Bob were doing the trick.

I ran into similar effects again when I modded my networks again to CS II status with Bob's 400Hz and 4500Hz kits, adding another 2uF cap to the tweeter, a 500uH inductor and a 3uF cap to the squawker. Again, after about an hour or so of playing, everything smoothed out and started sounding better.

Give those new caps a week or so, then you'll hear everything starting to lock in. []

[Malcolm]

Heresy IIs sound different than Heresys. They have different squawker drivers and tweeters.