At it again; '69 SuperLead build

You have a mix of carbon comp and metal film (?). What looks like old mustard caps and sozo. Would you mind filling me in on where you think carbon comp makes a difference to the tone vs. modern. Same with caps.
 
PhilC said:
You have a mix of carbon comp and metal film (?). What looks like old mustard caps and sozo. Would you mind filling me in on where you think carbon comp makes a difference to the tone vs. modern. Same with caps.
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He's got metal oxide (and a few metal film) in the power rails. That's a good spot for those because they have better power ratings, surge, and thermal properties.

He has carbon comp in the signal, and other places where voltage swings. This is for that vintage appeal/sound, however i'm not sure if those are NOS carbon comp, or new manufacture.

My thoughts, new carbon comps are like vintage tube re-issues, they are not the same, nor do they sound the same. The same materials are just not available anymore. Now that being said, they don't sound bad or anything, you just need to use them in spots that sound good to you. I personally just stick with carbon film, unless NOS is available.
 
PhilC said:
You have a mix of carbon comp and metal film (?). What looks like old mustard caps and sozo. Would you mind filling me in on where you think carbon comp makes a difference to the tone vs. modern. Same with caps.
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Like CrazyNutz said, its a mix. Metal oxide in power rails and metal film or carbon film if its either in the bias supply or mounted on a socket. Not going to mount CC on a socket nor use it in the bias supply. The rest are CC and almost all are NOS Allen Bradley. The only non NOS CC I can remember is the 10k in the PI.

From what I've read the main spots for CC are the slope resistor and NFB and then diminishing returns after that. I was hesitant to use them for V1 plates due to noise but I've had that 110k V1b plate resistor for 20 years (military surplus/supply) just waiting for the right spot so I went with it. It measured 119k before I put it in.

As far as caps, the earlier in the circuit the more difference it makes. I wanted Mustards but finding 22n Mustards for a good price wasn't happening so I put Synergy Royal Mustards in the tone stack, 18n Mustards on V1a (bass channel that I never use) and PI input and 39n Mustards in power amp. V1b is a 2n2. The 100n on the other grid of the PI doesn't really matter since it is just bleeding all signal from that grid to ground so I just used an old gen Sozo.

Most of this is probably inaudible and at the price of potentially more noise. But it looks cool.

IMO, the caps that make the most difference are the mixer, treble, and bright cap. I found those NOS El Menco domino 560pF mica caps on ebay, I bought 10 of them. Then the Lemco 5000pF bright cap from a '76 50W that Shea modded. Glad I tried that thanks to CrazyNutz.

Oh yeah, I added the CDE caps to the V2a cathode and Presence because I saw that in the Suhr SL68. He doesn't have to use that extra cap on V2a but he chooses to...so I assume it matters. I didn't do a before/after test...sounded great before and after I added it. But once I go to the trouble I have reason to not want to remove it. I don't pretend to have dog ears and be able to hear all this stuff.
 
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I feel anything around 5000pf for a bright caps brings a certain amount of aggression and crunch to the tone a Marshall in the plexi superlead era.

Now the NOS construction of Lemco and Mallory make affect things more when compares to how new construction ceramics sound when used in the bright cap position you really have to swap them back and forth but I guarantee you will hear a difference if you are picky about your tone.
 
What surprised me was how thin it sounded with volume on 6 and a 500pF or 390pF cap. The 5000pF sounded really great at 6.

I think I'd rather have no cap or the big ~5k.
 
This thing sounded great from the jump but just had too much noise. I didn't rip it apart although I tried things I thought would be it. So I took it to a local tech and he discovered that the heaters were not balanced. He disconnected the heater center tap and used the 2x 100ohm resistors a la vintage Fender. That helped quite a bit. I got a 5W 100ohm pot that I might try to further balance it.

I also swapped the V1 NOS CC resistors for new CF. Used 110k on Bright channel. And then I mounted some CF 68k input resistors right on the jacks and ran shielded cable to the V1 grids. This got rid of some of the excessive hiss on the Bright channel.

Also got rid of the poly cap on V2 cathode. I can't hear a difference.

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I still need to take a good pic of the Elsweyr Dragon badge on the front. I love it, some will think it looks ridiculous. Here it is with the purple Mandalorian Superbass and friends.

I'm not putting my name on it, not putting Marshall on it, and nothing looks too barren. So...dragons and stuff.

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God, I really envy you guys that can do these builds… I am tempted to sign up for some type of online course, not sure how much I could learn in my 50s…
Then again, with my crazy OCD, I would be tweaking 24/7 and never playing the thing😑
 
SQUAREHEAD said:
God, I really envy you guys that can do these builds… I am tempted to sign up for some type of online course, not sure how much I could learn in my 50s…
Then again, with my crazy OCD, I would be tweaking 24/7 and never playing the thing😑
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You can totally do it. The older amps are super simple. But you're right about tweaking.
 
SQUAREHEAD said:
God, I really envy you guys that can do these builds… I am tempted to sign up for some type of online course, not sure how much I could learn in my 50s…
Then again, with my crazy OCD, I would be tweaking 24/7 and never playing the thing😑
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Bruce Egnater runs an amp-building seminar and I think Mojotone does too. I did my first one with no help other than final testing by my local amp tech. Turned out great and gets compliments all the time. It's really not that hard. I think getting good solder joints is the toughest part.
 
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