Cap job - ARS, F&T, LCR, affect on feel and tone?

[Squarehead]

This is my first post, I guess I have to start somewhere, so my one question is… I have to recap a few of my amplifiers and I would love to know your thoughts on the different filter caps (manufacturers) available and how they can affect feel and tone…
I understand this is not in the tone chain, but I have been told by many respected folks that it can in fact change the tone of the amplifier, other than just having new caps, ( which obviously will change the tone and feel of the amplifier just replacing all caps with new)
So, before I go out and buy all new filter caps, are there any traits or have any of you tried different ones in the same amplifier? Which ones do you prefer? Which ones do you dislike? Etc.
Thanks for any insight you could give me!
Good to be here,
Keith

[galaxiex]

I'm not so experienced... but F&T caps seem to be well respected.
I've used them, no complaints. Feel or Tone? Sorry can't help there.

FWIW I will *never* again buy or use Illinois Caps. (IC)

[cerrem]

The Electrolytic caps filter the AC ripple to help smooth out the DC, however they also pass the audio AC signal current for each stage of the amp.... ie the audio AC signal current would pass through the cap to chassis then back up through the cathode for that given stage.... Mostly the older vintage caps have significant ESR which tends to dampen the ringing associated with the stray inductance in the circuit ...This ESR also creates what is known as a ESR ZERO which rolls upper frequencies.... this gives a smoother organic sound without the ice-pick high frequencies.. The caps ESL will put the upper frequencies back in phase which also has a noticeable difference..These effects can be heard when the amp is cranked, since that when you make square waves and lots of transients when banging the strings... This is not hookus pookus...If you measure the caps on a Network Analyzer you can plot out the impedance of the cap and see these details as plane as day...With newer caps LCR is probably best sounding...then F&T .... JJ caps show the lowest ESR and Lowest ESL and tend to be a bit tippy on the highs for me....as for what sounds best is only subjective...

[Justin Thomas]

I won't use Sprague Atoms cuz they're 3 times bigger than necessary with an equally inflated price. I personally like F&T, IF I can get a matching value. I just really like the presentation, and they're nor priced for snooty cap experts. Never had a bad Illinois or JJ (though I only ever used one JJ!), either.

Any of those fancy bootiki caps? Funk Dat. Spend your money elsewhere. Same for bootiki resistors or anything else, especially trannies.

Justin

[The Dude]

I sometimes wish I'd saved every Illinois cap I've replaced just for show. There'd be shelves of them.

[Justin Thomas]

But is that because they're "crap," or because you've worked on a bazillion amps? I just know about the bad run years ago... And is any of the problems with them perhaps in some way related to the designs that use them?

Justin

[The Dude]

...... is that because they're "crap," or because you've worked on a bazillion amps? ......

Yes and yes.

[Chuck H]

All the info above is valid. Though I can't vouch for any correction of phase WRT to HF I will say that MOST amps are designed so that only out of phase stages share HV rail nodes with a dedicated filter. And in this case the term "filter" is a little misleading. The first HV rail cap/s are the main filters. A bit more filtering is achieved at the second node which usually feeds the screens. Once you get to the PI and preamp there really isn't much filtering left to do and the main purpose of the HV node caps is decoupling. This decoupling allows any signal riding on the HV rail to find it's way to ground so that it doesn't interfere with the signal chain. Because aluminum caps are less than perfect there is always some interaction. This is where galaxiex is going. Differing amounts of interaction have different affects on the tone. BUT!.. There are some amp designs that don't arrange the HV nodes to only share out of phase stages. There is a huge difference in criteria when this is the case because any positive feedback can cause instability. So the criteria needs to be arranged for individual amp designs. Each amp will have a different criteria and a different sweet spot for cap impedance. Now...

Short of using caps that are known to have very poor ESR or caps that are known to have very good ESR all the typical brand caps in between are really very close in spec. And any difference in tone with the exception of extremes will be negligible. So my advice would be to choose the cap with the longest spec'd longevity. Because who likes doing a cap job. And, again, now...

How many of the standard caps (Atom, F&T, etc.) actually spec their expected service life? I'm sure the info is out there. Good luck finding it. That's why I've switched to a brand that actually tells me what I'm getting on a spec sheet. I had to switch from axial caps to radial caps to do this. Something no self respecting boutiquey builder would do.

YMMV, but my point is that each one of your amps may respond best to a different cap. But that difference will be almost ignorable short of extremes (low or high) esr. So there is no "best sounding cap" and in this light it's MHO you're better off focusing on longer life for the part if you can find the spec.

[J M Fahey]

Mostly the older vintage caps have significant ESR

Yes.

which tends to dampen the ringing associated with the stray inductance in the circuit ...

Not significantly at Audio frequencies.
Stray inductance in an amplifier wiring in wire lengths measuring a few inches... if that much ... is measured in nanoHenries.
A 4" piece of wire has 118 nanoHenries inductance; hardly of any concern at all unless you are talking VHF/UHF or some pretty FAST digital switching and timing.
On a *Guitar* amp? .... forget it.

This ESR also creates what is known as a ESR ZERO which rolls upper frequencies....

ESR is, by definition, resistive.
How can a filter cap roll high frequencies beyond what is expected from the classic definition of a capacitor is a mystery to me, care to explain the mechanism?
If anything, since a filter cap shows higher impedance at higher frequencies because of series ESR, it would attenuate LESS of them.
That´s why sometimes a ceramic capacitor is used in parallel with a filter cap ... but normally not an issue on Guitar amps.
Even less on a Tube one ... might be of some use in a fast SS power amp supply.

this gives a smoother organic sound without the ice-pick high frequencies..

Ice pick I understand as annoying high frequencies, but reserve the word "organic" to cucumbers and carrots.
It´s been way too much abused in Audio.

The caps ESL will put the upper frequencies back in phase which also has a noticeable difference..

Please describe the phase-shifting-back-to-normal mechanism.

These effects can be heard when the amp is cranked, since that when you make square waves and lots of transients when banging the strings... This is not hookus pookus...

Sorry but so far it does sound like Magic Spells to me.

If you measure the caps on a Network Analyzer you can plot out the impedance of the cap and see these details as plane as day...

Oh, now I see.
Wrong tool and wrong test in this application, sorry.
We are talking slooooowwwww (by Digital specs) Audio signals.

With newer caps LCR is probably best sounding...then F&T .... JJ caps show the lowest ESR and Lowest ESL and tend to be a bit tippy on the highs for me....

Weird, lower ESR and ESL must filter higher frequencies BETTER since they will show lower impedance.
A good thing if you are shunting Audio, superimposed to rail DC voltage, to ground.

as for what sounds best is only subjective...

Amen brother

[tubedood]

Hey I have used Illinois capacitors with no problems so far... am I just lucky?

[Chuck H]

Hey I have used Illinois capacitors with no problems so far... am I just lucky?

Yes.


Just kidding. Considering I don't do repairs I've replaced a seemingly disproportionate ratio of Illinois caps compared to other brands, but they were all years old. Many were not enough years old though. No legs on those things.

[drewl]

Sometimes you get what you pay for, sometimes you don't

[Squarehead]

Thank you all for your responses, I so appreciate it guys…
If anybody has a couple LCR 50/50/500 caps, I will buy them from you, I have four, but I need six for one of my old Marshalls…

[Squarehead]

Thank you so much for all of your responses, guys… I appreciate it… If anybody has a couple of LCR 50/50/500 caps, I would buy them from you, I need two more so I have enough to do one of my old marshalls,

[Randall]

Grumpus alert.

I realize this 'filter cap affecting tone' discussion is not going away any time soon. But, in my view it does not concern me in the least, because if it does somehow affect tone, it is in a minuscule way that it simply does not matter in real world applications. Stage construction, humidity, age of strings, air movement, acoustic environment, even how hard the drummer is hitting all affect my perception of my tone more than the ESR of my filter caps. And all these holy grail of tone 40's and 50's amps we regard so highly, I propose those carbon resistors and whatever caps were chosen mostly by what was available and cost effective. If Leo had gotten a better deal on Shwartz caps and 20% sand resistors, that's likely what builders would be going for today, measuring them in lab conditions and discussing how much silicon in which sands sound better.

And don't get me started on coupling caps. I happen to like Mallory 150s because they sound good enough to me and they are fairly priced, and I've never had a problem, nor a complaint. I had a customer recently pay me to replace Gibson factory tone caps with $240 worth of BumbleBee replica tone caps in 4 Les Pauls. That's eight $30/ea hand painted caps that came in little furry pouches in a box with a certificate. Never mind that these caps simply shunted off some of his signal to ground, to him he now had "that Beano tone". Whatever.

I use F&T wherever I can because they seem solid to me, fairly priced, reliable, and I tend to trust German engineered products. If they made 25/25v cathode caps I would buy those too, but since they don't I use Sprague Atoms there. I will not use Illinois caps. When I worked at a Fender authorized shop it seemed the most common support recommendation was to "try replacing those XXX caps". They were almost always Illinois.

So give me reliability and consistency in a quality build at a fair price and I'm good. And to be perfectly honest, I don't really even know if I can or cannot hear a perceptible difference in filter caps in lab conditions, I am too busy being in the moment of the music to even care. There, someone had to finally say it!