Need component ideas for Blackface build

[dbts808]

With regards to tube amp builds, I once swapped out every carbon comp resistor for metal film ones and totally ruined the amp. I went back to carbon comps and the tone returned. After playing around with components for 20 years, here's my advice: use carbon comp resistors, Mallory 150's (more Fender-y than Orange Drops) and stay close to stock. The only mods I like are: a push-pull trem pot so that you can stop part of your signal from always being shunted to ground, a mid pot, a presence control, and sometimes changing the tone stack caps to a pair of 0.22's. No master volumes, or stacked gain stages, ... buy a great pedal or two for that. New filter caps and NOS tubes, and good speakers in good cabs, ... when properly tweaked, nothing beats a vintage Fender amp.

[Chuck H]

Interesting about the carbon comps. I would speculate that the original "good" tone was relative to drifted original resistance values except that you put CC's back in (new ones?) and got your mojo back. There are a couple of good write ups on line about the differences between resistors. And there are a couple of places in the standard BF circuit where it might apply. There are also many places where it wouldn't seem to. It might be interesting to determine key circuits and try resistor type changes. Maybe it DOES make a difference.?. I know (can tell) there's no convincing you otherwise now, but it may indeed be unimportant for MOST of the amp. Just sayin'. It would certainly be nice to narrow it down so that the lower noise resistors could be used wherever possible without tonal detriment. Like having your cake and eating it too

[dbts808]

Carbon Comp Mojo

Interesting about the carbon comps. I would speculate that the original "good" tone was relative to drifted original resistance values except that you put CC's back in (new ones?) and got your mojo back. There are a couple of good write ups on line about the differences between resistors. And there are a couple of places in the standard BF circuit where it might apply. There are also many places where it wouldn't seem to. It might be interesting to determine key circuits and try resistor type changes. Maybe it DOES make a difference.?. I know (can tell) there's no convincing you otherwise now, but it may indeed be unimportant for MOST of the amp. Just sayin'. It would certainly be nice to narrow it down so that the lower noise resistors could be used wherever possible without tonal detriment. Like having your cake and eating it too

Hi,
There might be places where metal film would be better; and I also would like to know where they are. I do not attribute the change in tone to "drifted" resistor values. Carbon comps are like single-coil pickups to me; the tone comes with noise, no way around it. That "noise" is pleasant the same way that tube distortion is pleasant; maybe the resistor distortion emphasizes even-order harmonics. I don't know about carbon film, but I immediately hated the metal film resistors and was amazed at how bad it made my '73 SFDR sound. I'm not into vintage as a purist, only because some of it truly sounds better. Carbon comps are warm, a little "noisy", and they may drift. Metal film are stable, accurate, and sterile-sounding. I would only use them if I was convinced they didn't hurt the sound. I too would like the best of both worlds if possible.

[g1]

I do not attribute the change in tone to "drifted" resistor values.

If you did not check all the carbon comp values as you replaced them, it is much more likely that the cause was due to drifting, rather than any carbon comp peculiarities.
I'm not trying to be argumentative, or even a skeptic, but compared to metal film, carbon comp drift a lot. From your description, there was a very big difference in tone (or you missed the noise ). If you had said you noticed a slight change would be one thing, but for "totally ruined the amp" difference, there would have to be some value changes.
Nobody who changes all their resistors over ever measures exactly what they were and uses those values for replacement. It's just not done, for whatever reason. The people that do replace by measured value are not doing wholesale replacement of all resistors.
RG Keen did an extensive analysis and found there were only a couple spots where it could make a perceivable difference, you can read about it here: http://www.geofex.com/article_folder...carboncomp.htm

[Justin Thomas]

Every time I use CC resistors they drift like crap just from soldering. No, they don't ever come back. Needless to say, I' ll use them if I have them, just not to bias tubes. Granted, I'm using New, not NOS. Maybe they just don't make 'em like they used to, but no 1/2W resistor is worth $2! Carbon Film is probably 75% of my use, Metal Film another 20%… CC gets the rest. I also have no problem using vintage pulls IF they are still in spec.

Justin

[Chuck H]

Only because there IS some mojo attached to CC resistors (and I mean mojo in the real, not imagined sense as it has been recognized), I had previously built vintage type designs with CC for the entire signal path, metal film plate resistors, metal oxide in the power supply and I don't know what all else. I used metal film on my last two builds and have no complaints. Would they be better with carbon comp? I dunno. I'm not going to trouble with it because I have no complaints. Maybe it has a lot to do with just fine tuning any amp as it is. Now that these two are tweaked to sound "right" with metal film it's possible that carbon comps would detriment the tone. After all, they aren't inherently better. Just different. Their particular qualities may be just right for a stock Fender circuit. Maybe not so much for others.

Just thinking out loud. It would still be interesting to find out if there are key places to use them for a potential tonal difference/benefit. Pretty low on my priority list right now.