Marshall caps....what type?

[Delta]

Hi again,

as stated before, I'm a computer technician just stepping up to the level of guitar amps, so please bear with me if I'm asking some "stupid" questions in the beginning

1. In Marshall amps I find some caps looking very similar to resistors, with color coding and all. What type are these?

2. Can they be replaced with for instance polypropylen caps?

3. Will replacing the caps with something "unoriginal" affect the sound in any way?

Kind regards Klaus

[Enzo]

The little ones that look like resistors except are maybe light green instead of brown or something like that are ceramic. The color code reads like a resistor except in pf instead of ohms.

Caps are caps, so if you meet the value and voltage spec, you can sub anything you like. I can't imagine just replacing them in an amp for no reason. But if you are building an amp from scratch, then you can use film caps, silver mica caps, disc ceramics, etc.

Many guys swear by replacing existing generic caps with something more fancy, for edxample the every present "orange drops" or Mallory 150s. But to me the differences are subtle. Only you can determine if it makes much difference to your ear. You'll never go wrong using good quality parts.

You can even replace electrolytics with film caps. They'd be the size of a football, but you can do it.

[Delta]

Thanks for the info, Enzo....

My reason for asking was that I want to clone my 8008. Very good amp not made any more!

But why Marshall use ceramics? I read some information that ceramic caps is the worst possible option in audio circuits?! Anybody has some opinion on this?

My option would be metal film resistors and polypropylene caps to reduce hum and noise....am I right or wrong?

[Twist]

Most big amp manufacters use the cheapest components they can find. I'm sure they have teams of guys that do nothing but find ways to shave off a few pennys here and there. And yet they still produce fairly good sounding amps (sometimes).

[hasserl]

But why Marshall use ceramics? I read some information that ceramic caps is the worst possible option in audio circuits?! Anybody has some opinion on this?

I'm sure there are plenty of opinions about it. My opinion is cap type and brand has been greatly over hyped by amp guru's over the years, and with the internet the hype is magnified several thouseand times. Just stop and think about what you've written; i.e. you have an amp from a manufacturer that is world renown for building great sounding amps, the amp sounds great to you, but you discover that is has parts in it that according to conventional wisdom are supposed to be the worst possible option for audio circuits. How can that be? Perhaps conventional wisdom is not all that wise? Think about it, and don't believe the hype.

But that's just my opinion, I'm sure others have their own. When it comes to discussions on these things we tends to see quite a few.

[mac1amps]

I couldn't agree more on the "over hype" factor, ESPECIALLY with respect to the infamous "orange drops". For myself though, I would have to admit that I [usually] like the results of changing lower value ceramic caps to silver mica's (especially in a tone "stack")......then again, I've heard a lot of nice sounding old Magnatones, Supro's, National's, & the like, that have ceramic caps, and sound gorgeous.
I get the impression, that a lot of DIY'ers (and a lot of less experienced techs) are totally convinced that new "signal" caps will make a HUGE difference, so after they've changed them all, there's a [what I call] a "placebo factor" that supports their "brain washing".

[Rick Erickson]

[But why Marshall use ceramics? I read some information that ceramic caps is the worst possible option in audio circuits?!]

In "audio" circuits, or audiophile circuits they probably are. But a guitar amp is not truly an "audio amplifier", it is part of an "instrument" which produces a sound. The kind of audio circuit you reefer to is a "sound reproduction" circuit in which the lowest possible distortion is usually the goal. Guitar amps often embrace various forms of distortion as a part of their signature. You would not likely find, for instance, the common tone stack used in most guitar amps in any hi-fi audio preamp circuit. There is no truly flat setting of the controls, as was pointed out in the original Alembic Bass Preamp Owner's Manual. The coloration of these controls is a large part of what we perceive as guitar tone. Sometimes guitar amp components were chosen for economy, and because these amps are now "classics" many people assume that there was great tonal consideration given to every resistor, capacitor, star washer, nickel-plated screw etc.. Quite often it's the simplicity of the circuit that makes it special. It has been my opinion over the last 30+ years that the more complicated a circuit becomes, the harder it is to make it sound good. Just my $0.02.

RE