Does capacitor brand really make any difference?

[PelliX]

It's lower and you're finding the octaves. It might be the 60 HZ AC coming out of the wall causing it.

I think you mean the harmonics, so 60, 120, 240. Could well be. If it's 120Hz it's coming from the rectifier, so I'd check the filter caps.

 

[NickKUK]

I'm quite an evidence based person.

I've done a few recaps of old 30+ year old design hifi amps and other equipment, some solid state and some tube based (including an old 1957 receiver).

There's a few things that get lost in the discussion:

Specifications - specifically the DC and AC ratings. Most people seem to look at a single rating but actually an AC rating is as important. You may have a 400V DC rated film cap that then has a sub-200V AC rating. If your cap is dealing with a high gain output where the signal is driving a larger tube, then you may find that AC rating is going to cause you issues. A lower AC rating will end up distorting the signal at higher amplitudes (which could contribute to the NOS/vintage tone).
Specifications also indicate you're going to get a batch of 10 caps that are similar enough to substitute - this is where boutique starts annoying me, specifically where they don't provides a specification sheet, specifically showing the frequency vs ESR, etc

Now specifications, from experience don't make sound/tone.
Reason I know this is from replacing old Jamicon electrolytics in the signal path with Panasonic film caps only to find the sound being dark and muddy. I then switched for WIMA MKP10, not impressed but then WIMA MKP4 which gave clarity.
Now the reason I say - make tone/sound - is that the design (power supplies/components/signal design) all vary the environment that the substituted cap is placed in. The result can cause variation between amps, especially those that have had some drift due to thermal cycling or temperatures.
After switching the Jamicons to CDE (power), Panasonic low ESR organics for pre-stage decoupling and moving to film for the signal coupling caps, lastly switching out the cooked underwattaged resistors for larger metal oil Dale etc, it increased clarity.. that then ended up changing out the opamp pre ... etc etc.. The amp had lost a chunk of it's old character of tonally muddy class AB (heavily biased to operate the majority of it's time in class A), to be come a clear sounding with nuances that showed up the media being used.
Good power caps - back to the specs - that give better ESR at 50/60Hz are going to be better suited than those that are tuned for higher frequencies. The larger the cap, typically the better the ESR. Old caps tended to have a wider applicability for purpose, new caps (by design) tend to be more specialised.
I've directly Bode tested the caps for Panasonic, WIMA and Vishay, and the low voltage bode test does not show any statistically significant difference. What is important here is to place cap in the amp and then give it the full DC and AC through the amp and then check the bode plot.

Having said that a considerable amount of tone is made from so many unspecified components it's quite difficult to define the tone.
* resistors - thermal noise, etc
* caps - DC + AC effects like compression and distortion, blocking, phase shift at frequency etc that can change with temperature.
* tubes - different noise and transconductance with frequency based on previous state (ie a DC, vs AC vs pulse will have different outcome based on the thermal levels off the cathode/heaters, capacitance etc in the tube itself).
* diodes ..
... and the list goes on with power transformers and output transformers.
* line wall voltage and the noise that causes additional distortion effects

Manufacturers like Marshal and Fender are always looking for a statistical similarity but they know they'll never make two amps the same. You'll end up with a stunning amp, a plain Jane and Friday-PM special.. just by the component lotto.

Back to subject.

Caps I like
* Vishay MKT and MKP film caps - not had an issue and sound good.
* WIMA film caps - the massive FKP1s are clear as a bell but they're not audio caps! The MK4 are great sounding for hifi (630Vdc, 400Vac are the ones I like!).
* Panasonic low ESR organics for close in power decoupling

Caps I have no real preference or dislike for
* Panasonic power electrolytics
* CDE power caps
* F&T electrolytics (450V and 500V) although they seem a little slow.

Caps I'm less enamoured by:
* Panasonic film caps
* WIMA MK10

Caps I've not tried and don't have experience of
* Sprague
* IC
* Boutiques like Mundorf, Jansen, MOD
* RS NOS (any NOS electrolytics is very very likely to be way past it's life/shelf life)

So you can see - I don't see a guitar amp as an alchemist/witches brew but something that can be characterised (although with large numbers of variables). I don't mind boutiques IF they can provide visibility of the magic sauce that gives them the ingredient within the tone and they can provide that on a consistent basis with each batch.
If you're not giving a datasheet then.. I start asking uncomfortable questions.

 

[PelliX]

So you can see - I don't see a guitar amp as an alchemist/witches brew but something that can be characterised (although with large numbers of variables). I don't mind boutiques IF they can provide visibility of the magic sauce that gives them the ingredient within the tone and they can provide that on a consistent basis with each batch.
If you're not giving a datasheet then.. I start asking uncomfortable questions.

I'd hang that on my workshop wall.

 

[ThreeChordWonder]

All very nice chaps, and I'm sure you're all correct, but I, for one, am not chasing perfection (whatever that is), just good enough.

Rabbit hole?

 

[NickKUK]

Rabbit hole?

View attachment 158480

That's either a Jamicon or CapXon cap.. Rifa was square bodied

 

[PelliX]

All very nice chaps, and I'm sure you're all correct, but I, for one, am not chasing perfection (whatever that is), just good enough.

Rabbit hole?

View attachment 158480

Aaww, it's thirsty! It needs electrolytes. They're what plants capacitors crave...