Speaker Recap - Electrolytic or Film?

[Retrovert]

I always thought it was a matter of less output per driver with the oldest cap, thus brighter sounding with the new ones.

I believe that was his point.

The high ESR capacitors, which often have high leakage (forgot to point that out), are attenuating the signal. So there's less output because much of the signal is being converted into heat.

A lower-loss capacitor now passes more signal, so the driver is louder, often shockingly so.

I heard a funny story about someone who rebuilt a crossover for the original owner who had bought them in the 1960s. When he heard them he said, I haven't heard that sound since I brought them home!

 

[tubed]

I've done recaps before and I've noticed the "cost savings".
I would have replaced iron with air core but never thought the expense would be "heard", so to speak. Something to consider.
Again, thanks for the insight.

 

[musichal]

I always thought it was a matter of less output per driver with the oldest cap,
thus brighter sounding with the new ones.

??

 

[tubed]

I believe that was his point.

Yes, but I didn't associate "muddiness" to compensating by turning up the volume to make up for any degree to which the output is compromised.

 

[Retrovert]

It is hard to hear the difference in the abstract unless one has a very, very good ear. Bud Fried could instantly identify where driver resonance occurred, and could describe how a crossover was built just by hearing it. (I can't do that, BTW, nor do I personally know anyone who can.)

But one can hear the improvement of bypassing and using air cores. It is subtle and it's not that I care about the accuracy, per se, it is that it is more pleasant and less fatiguing to listen to speakers with lower distortion. You often can't put your finger on it, but the sound is both different and pleasing.

You need not spend a fortune on air cores. Whatever has a reasonably low DCR, like 16 gauge, is likely perfect. I would not spend money on ribbons. This matters a lot more for the midrange where we far better hear. So if you only have a small amount of cash for new inductors, the midrange would deliver better results.

 

[tubed]

??

I suppose I don't associate less output with muddiness.
Assuming a speaker was manufactured with parts of the same age, all the capacitors of that speaker would be equally of less output, theoretically in balance.

 

[Retrovert]

I suppose I don't associate less output with muddiness.
Assuming a speaker was manufactured with parts of the same age, all the capacitors of that speaker would be equally of less output, theoretically in balance.

Three issues.

One, the sound is muddy at all volumes.

Two, the sound level is reduced because of attenuation. So one turns up the EQ (or the treble control) to get muddy sound at a reasonable volume.

Three, The balance between the drivers may have changed over time as the capacitors aged.

With a new tweeter capacitor the sound is no longer muddy and is louder. So suddenly that treble is vibrant and present, and this can be disconcerting.

I always suggest an L-Pad for the tweeter volume as it allows perfect adjustment.

 

[tubed]

It is hard to hear the difference in the abstract unless one has a very, very good ear. Bud Fried could instantly identify where driver resonance occurred, and could describe how a crossover was built just by hearing it. (I can't do that, BTW, nor do I personally know anyone who can.)

But one can hear the improvement of bypassing and using air cores. It is subtle and it's not that I care about the accuracy, per se, it is that it is more pleasant and less fatiguing to listen to speakers with lower distortion. You often can't put your finger on it, but the sound is both different and pleasing.

You need not spend a fortune on air cores. Whatever has a reasonably low DCR, like 16 gauge, is likely perfect. I would not spend money on ribbons. This matters a lot more for the midrange where we far better hear. So if you only have a small amount of cash for new inductors, the midrange would deliver better results.

Next x/over project I will try air core only and multiple bypass, just for the thrill of it all

 

[tubed]

Three issues.

One, the sound is muddy at all volumes.

Two, the sound level is reduced because of attenuation. So one turns up the EQ (or the treble control) to get muddy sound at a reasonable volume.

Three, The balance between the drivers may have changed over time as the capacitors aged.

With a new tweeter capacitor the sound is no longer muddy and is louder. So suddenly that treble is vibrant and present, and this can be disconcerting.

I always suggest an L-Pad for the tweeter volume as it allows perfect adjustment.

I suppose one can figure capacitors of the same year/make will age equally with the same time duration?
Or can capacitors age better than others even of the same batch.

 

[musichal]

I suppose I don't associate less output with muddiness.
Assuming a speaker was manufactured with parts of the same age, all the capacitors of that speaker would be equally of less output, theoretically in balance.

That theory is out of alignment with my experience. I've recapped several pairs of speakers because I noticed a difference in output between the tweeters of a pair - and these were all sequentially numbered with the same parts, so there was no age difference. Of course, I recapped both speakers in the pair, and balance was restored.

 

[tubed]

That theory is out of alignment with my experience. I've recapped several pairs of speakers because I noticed a difference in output between the tweeters of a pair - and these were all sequentially numbered with the same parts, so there was no age difference. Of course, I recapped both speakers in the pair, and balance was restored.

I can't recall that type of failure where balance between drivers stood out.
I did once have a midrange capacitor go dead.
No doubt cap values slowly have drifted out of whack but the brain seems to make up for that phenomenon.
Then measurements are in order for the enthusiastic hobbyist.
Time to recap.

 

[musichal]

I can't recall that type of failure where balance between drivers stood out.
I did once have a midrange capacitor go dead.
No doubt cap values slowly have drifted out of whack but the brain seems to make up for that phenomenon.
Then measurements are in order for the enthusiastic hobbyist.
Time to recap.

In the case of a pair of Paradigm 7se Mk II speakers, the difference between the output of the L/R tweeters was obvious to anyone. With the Klipsch Forte I, the imbalance was subtler, and I didn't notice it for hours, but it was undeniable when I did, then used frequency test tones to confirm. The Khorn's imbalance was quickly obvious to me, but not to others in the room (none of them enthusiasts who've spent a lot of time listening closely), but, again, with test tones, all then heard it. And finally, a pair of Paradigm 3se, not too subtly the same problem. Apparently, I am sensitive to HF imbalances within my range, which falls below normal threshold of acuity between 10 and 12khz. These differences all could be easily detected, even by novices, with the use of test tones. I noticed them with music. I'm pretty convinced that if everybody tried HF test tones with their vintage speakers, many would be surprised, and there'd be a lot more recapping going on. I could be wrong and look for no debate, it's just where my own ears and experiences have led me. As always, YMMV.

It is the kind of anomaly that can't be unheard once noticed. You just have to heat up some iron and melt some solder and feel like a man doing manly things with manly tools.

 

[StimpyWan]

ESR worsens over time....Noise also goes up over time.

You are correct sir, or should I address you as "Mr. Film Cap"? When performing my AR90 A-to-B test, my son walked through. He stopped and listened for a few seconds, then pointed at the stock speaker, and asked, "why is that one distorted"? "It's got static in the sound", "the other one sounds clear". 'Nuff said.

 

[musichal]

I suppose I don't associate less output with muddiness.
Assuming a speaker was manufactured with parts of the same age, all the capacitors of that speaker would be equally of less output, theoretically in balance.

Can't agree with that second statement at all, based on my experience. As for the first, "dull" is a better descriptor than muddiness, I agree. However, I do think bad caps can have impact on upper bass sound, though I freely admit that I don't know that for certain. It just seems to be what I've heard sometimes (after a recap). Assuming a speaker was made with caps the same age surely can't guarantee they will degrade identically over time, can it? Bell curve, if nothing else can explain that.

As for what I've heard - it was not my imagination that two tweeters differed audibly in level and were corrected with recap. Can't understand why the doubt. With the Paradigm 7 mentioned above, it was immediately obvious, even to non-enthusiasts.

 

[Retrovert]

I suppose one can figure capacitors of the same year/make will age equally with the same time duration? Or can capacitors age better than others even of the same batch.

The capacitors in a given manufacturing group should be so similar you will be unable to hear a difference between them as they age.

The bigger issue is that if the sonics are deteriorating the capacitors have failed and require replacement.

Look at the manufacturer's numbers for lifespan. Derate for being harder driven or in warmer environments (like cabinets).

 

[Retrovert]

I'm pretty convinced that if everybody tried HF test tones with their vintage speakers, many would be surprised, and there'd be a lot more recapping going on. I could be wrong and look for no debate, it's just where my own ears and experiences have led me. As always, YMMV.

Yup. The A/B is amazing. I know of one case where the owner A/B the speakers after upgrade where the only change was the crossover: one crossover used film capacitors and the other used vintage PIO. So it was a fair comparison. The bypassed films sound better (and exquisite) because the ESR is far lower. The owner was severely dismayed after having spent a pile of cash on old, tired, wheezy capacitors which everyone "knew" would sound better.

The effect is sometimes more pronounced with music, because the signal wildly varies, than with sine waves.

 

[corbin]

Okay Mr. Film Cap you've worn me down into considering a Dayton poly with film and foil bypass. It seems the additional capacitance of the bypass cap would function like ESR in a NPE to slightly attenuate high frequencies but without the drawbacks of distortion, noise, etc.

May also order a regular ol' NPE for comparison.

 

[StimpyWan]

...It seems the additional capacitance of the bypass cap would function like ESR in a NPE to slightly attenuate high frequencies....

Uh, no. Parallel resistance is not additive. Parallel capacitors, including a cap and a bypass cap, will exhibit even lower ESR. So, even clearer sound...!!!

 

[toxcrusadr]

To paraphrase Zilch, "More Burhoe, less wank!"

Seriously though, great thread, following with interest.

 

[Retrovert]

Okay Mr. Film Cap you've worn me down into considering a Dayton poly with film and foil bypass. It seems the additional capacitance of the bypass cap would function like ESR in a NPE to slightly attenuate high frequencies but without the drawbacks of distortion, noise, etc.

May also order a regular ol' NPE for comparison.

I think you are confusing several different properties.

Capacitance in parallel sums to a larger capacitance. It does not add any series resistance. Quite the opposite. Two resistors of equal value in parallel have half the resistance. ESR, which is internal resistance, is therefore decreased by half. (Assuming equal values.) So two capacitors with equal ESR will, when placed in parallel, offer half the ESR of a single, larger capacitor.

The conductors in a capacitor are imperfect and have resistance, which is how ESR arises. Some types of capacitors, such as electrolytics and PIO, have very high ESR. Others, like film, have very low ESR.

The bypass capacitor adds a lower resistance path which offsets the resistance (ESR) inherent in the NPE.

ESL, the Equivalent Series Inductance ("L" is the symbol for inductance because of the pioneering work by Heinrich Lenz) similarly functions. A capacitor is a coil of foil, so it has inductance.

I again urge you to do the simple experiment I outlined: read the value of the capacitors in your existing crossover from the side of the capacitors and plug them into the formula. If the numeric value produced matches the official crossover points in the published specifications then ESR was not a factor in the crossover design. This is a simple, and trivial experiment which will be completely dispositive of the issue. No need to chase your tail on this.