Electrolytic caps

[Colossal]

Maybe Dave (colossal) will see this thread and respond but I remember him talking about the short leads being a problem for soldering into the board.

The main difference is life expectancy I would assume with film cap vs e-cap. Solen fast caps are good but physical size makes exacting pre-planning a must.

Mark

I have built numerous amps using film caps in the power supply. These caps are typically designed for PCB radial mount and have very short leads, on the order of 7mm. I solder leads to them quickly (in and out) so as not to overheat the cap film. I've never had any issues. Carr Amps uses Solen Fast Caps. Solens are axial leaded and have long leads, which is convenient. As Mark mentions, a great advantage with these is extremely long life, however, due to their large size, traditional layouts may need to be adjusted to accommodate them.

[R.G.]

People who feel they can hear hints of oak and a finish of parsnips and rutabaga in amps built with teflon boards and solid gold wiring are immune to being convinced that any component, no matter how minor or trivial, does not cause some change in sound. It's the hifi tweako virus, infecting the guitar amp world. In the hifi tweako world, the purported "Golden Ears" have stopped responding to requests for them to participate in correctly constructed double blind tests largely because the tests show that their ears distinguish whether one component is different (let alone better!) no better than random guessing, and often ... worse ... based on what they say before the test.

I've occasionally thought about giving in to the Dark Side and making an hermetically sealed amp case filled with dry nitrogen gas, then developing a mythos to support these very expensive units, including periodic maintenance involving evacuating and re-filling them because of hydrogen diffusion through the metal walls. I just can't make myself do something so dishonest.

A few years back I came up with an idea that I called "The Immortal Amp", being simply a tube amp that has the normally fungible parts replace with parts with longer life. Film based caps, especially motor-run type caps, were part of that whole setup. Predictably, there were nay-sayers that criticised the idea, saying (without trying, naturally) that film power filter caps would make the amp sound too sterile. No amount of pointing out that you could add external ESR and leakage to your heart's content and tune these long lasting caps to be as bad a cap as electros as your ears told you was better ever got through.

Sigh., It's the people that are the problem!

[martin manning]

RG, do you think there is an audible difference in the sound of caps in the signal path with different dielectric materials, such as polypropylene vs. polyester, or ceramic vs. silver mica?

[nworbetan]

Similar to Martin's question, is the ESR in a good (i.e. not failing) electrolytic cap enough to make a difference as a cathode bypass cap?

[pdf64]

...I'm firmly of the same opinion of xtian here, as the power filtering caps aren't even in the signal path, and from everything I've read/seen, they have only detrimental impact on signal path if they're not filtering enough, and they add crappy tone/hum, but if they're working, they're transparent...

I'm of a similar opinion, yet I don't think that the impact of parasitic effects of functional power supply bypass caps on the sound / response of an amp can be totally ignored.
Their ESR may only be a few ohms, but consider what job those caps actually do, ie handle significant ripple current, make the Vac at power supply nodes = 0.

Bear in mind that for the actual 0V / circuit common system in an amp, the tiny fractions of an ohm involved in eg a copper buss bar or chassis metalwork, can result in massive hum screwing up the amp's operation, if it's not carefully accounted for.

The ESR of caps is several orders of magnitude higher than that, and the currents flowing will be significant, so I think there's potential for varying levels of ESR in functional caps to have varying degrees of effect on the tone / response of an amp, also bearing in mind that ESR is also likely to vary over the relevant frequency bandwidth.

It's not as if ESR is a simple characteristic to measure (especially at normal working voltage), or that there's a generally accepted 'go/no go' criteria we can apply.

So whilst the 0V conductor type may not normally be thought of as having a tonal effect, I'm not certain that we can treat power supply reservoir / bypass cap type characteristics similarly.

[pompeiisneaks]

...I'm firmly of the same opinion of xtian here, as the power filtering caps aren't even in the signal path, and from everything I've read/seen, they have only detrimental impact on signal path if they're not filtering enough, and they add crappy tone/hum, but if they're working, they're transparent...

I'm of a similar opinion, yet I don't think that the impact of parasitic effects of functional power supply bypass caps on the sound / response of an amp can be totally ignored.
Their ESR may only be a few ohms, but consider what job those caps actually do, ie handle significant ripple current, make the Vac at power supply nodes = 0.

Bear in mind that for the actual 0V / circuit common system in an amp, the tiny fractions of an ohm involved in eg a copper buss bar or chassis metalwork, can result in massive hum screwing up the amp's operation, if it's not carefully accounted for.

The ESR of caps is several orders of magnitude higher than that, and the currents flowing will be significant, so I think there's potential for varying levels of ESR in functional caps to have varying degrees of effect on the tone / response of an amp, also bearing in mind that ESR is also likely to vary over the relevant frequency bandwidth.

It's not as if ESR is a simple characteristic to measure (especially at normal working voltage), or that there's a generally accepted 'go/no go' criteria we can apply.

So whilst the 0V conductor type may not normally be thought of as having a tonal effect, I'm not certain that we can treat power supply reservoir / bypass cap type characteristics similarly.

This is absolutely true, but not related to the capacitor 'function' and is more common in electrolytics as I recall, and is related to any electrolytic. Therefore using the non electrolytic caps you get significantly lower ESR. Example, I looked up a CDE 250V 20uF cap electrolytic and it has expected max ESR of 12.5 OHMS the same value TDK film capacitor has 26.8 mOhms for a 1uF, the didn't even get up to 20 uF but the 10uF at 250 was 4.2mOhms So we're talking elytic in ohms and film in milli ohms. Big difference Thus it's even better for that type of thing.

You're spot on of the problems of any capacitor, but the film ones effectively remove this problem. (I may be doing something wrong with the datasheet here, but I'd also recalled hearing this somewhere else as well, but basically couldn't remember where so I wanted to back it up with data from the datasheets).

~Phil

[Swankmotee]

I’m just asking for your take on any other brands you might have tried in your amps that you feel are better sounding than the current crop of offerings. They definitely do have an effect on the overall sound and feel of the output section thus the reason for the question. The only ones I’ve decided I’m not a fan of are the ones I mentioned so I guess the consensus with most of you is you don’t hear any difference between different brands then.

[sluckey]

I like the Illinois (IC) brand.

[dbeasley]

The problem is your question is so objective and loaded, considering how ridiculous the debate over caps has been - especially in HiFi circles. If you can hear large, quantifiable differences between caps and have some real evidence that's not subjective then please be my guest.

Where are my Rhodium plated power cables....



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[dbeasley]

There is a reasonable argument in differing values though. Raising or lowering the actual value does clearly and quantifiably change how the amp reacts, especially during quick transients.

FWIW, JJ/F&T make a can cap that is a drop in replacement for Marshalls. In a few different values. Do they sound different? Versus a worn out, leaky Daly that's 40 years old? You betcha.



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[SoulFetish]

I use these film caps in my builds, and I love them. The "DC Link" film capacitor has been a great bit of development for tube amplifier builders. The specs meet (and in many ways far exceed) our requirements for power supply design, and the funny part is that our needs were never even considered by the industry at large. These were designed for SMPS, high voltage IGBT inverters, etc. I use them because they are superior to electrolytics in virtually every way.
Honestly, I really have no idea whether or not they sound better. They ONLY way to tell would be to build an identical amp substituting in electrolytic caps, or switch them in and out in the same amp. Then run a series of blind tests where the tester, nor the subject knew which was which. But that sounds too much like work.
My developing opinion is that the power supply is the heart of an amplifier; that how it is designed and constructed matter. Isn't the modulation of the power supply what you ultimately hear when it's all said and done anyway?
As far as the film caps go, here is what they look like in my build:

Completed Wiring.jpg

oh, I'm not sure if there where questions about whether or not the ones with 4 leads was a multi-cap case? If that's confusing, here is the skinny on what the difference is:
the packages with 4 leads provide a lower ESR by about half those with two leads and the added benefit of a more secure board mount. It's easier to describe the pinout configuration with a quick drawing, rather than explaining it poorly.

4-2 lead configuration.jpg

[tubeswell]

Awesome stuff SoulFetish.

[bluesbreaker62]

Anybody got experience with comparing electrolytics in the power supply for best tone? Is there one brand that sonically outshines the others? I’m getting ready to recap my 73’ 100 watt Marshall and want to get as close to the old Daly’s as possible. Thanks in advance!

Hi Swankmotee, I had an email conversation with Larry of Larry amps (who, I think we can all agree, knows a thing or two about electronics) about this very issue.
I recently bought a 1970 JMP he converted to one of his Dino circuits some time in the '80's.
The amp still had the original ERIE caps and I was a little conserned about their performance and reliability.

Here's the reply I got:

"Don't swap the electrolytics, as long as they measure at least 80% of their rated value and as long as they don't fail.
Discharge the electrolytics gently (through a 100K resistor to ground) before measuring them.
The Erie's (as well as Daly's and LCR's) contribute to the overall amp's sound & behaviour and you never will have the same sound, when the amp is supplied with electrolytics of current production."

Hope that helps

[Roe]

Yes, Larry knows marshall caps well. The bc axials are nice but there are not too many options for radials

[Roe]

SteveM uhhhh no. I’m looking for stock and F&T’s, JJ’s, and the baby blue one that the name escapes me sound flat and varying degrees of one dimensional thus the point of my original question. For a brief moment in time SoZo was making an excellent sounding Daly clone but stopped production. CE offers a very low ripple can that I recently used in another 73’ Marshall that sounded very good overall so more than likely I will end up using them again. The ones I’m replacing are Elna’s which are audiophile types which are fine but too stiff for my tastes.

I removed six sozos from my amps, preferring lcr or even f&t. Lcrs got more punch and harmonics than the sozo 100uf super cap