FourT6and2
Well-known member
1970 Super Lead. Looks to be in decent shape. PT is a replacement Mercury Magnetics MP100-475. This works fine for now but I do have a vintage clone from Marstran on order. Though I haven't decided if I'm going to install it or just leave it as is.
A small handful of the original solder joints look to have been reflowed. Mid pot is an older Alpha replacement. The 0.68uF in the third stage looks to have either been added or the original was replaced. And the input grid wire on the third stage was replaced with shielded coax for a "hot shield" mod. There does seem to be a lot of noise coming from this part of the circuit. Tapping on the second stage's coupling cap and/or the treble peaking cap produces a loud pop/bang.
A few of the resistors measure too high or too low and might need replacing if I want to nit-pick (like those carbon films in the B+ line). The 220K PI grid leak/output resistors also measure a bit off for comfort. One measures 208K and the other is also off but I don't remember the exact value.
Will replace the cement screens with Welwyn 7W.
The stubby 0.1uF presence cap and Wima 0.1uF in the PI are both original. But looks like Marshall might have run out of 400v 0.1uF caps and used these instead. I might leave them in since they're original, but I kinda want to replace with the period-correct Philips to satisfy my OCD.
I plan on re-capping the bias caps at the very least. And possibly the filter caps since they're so old, although they show no signs of wear. The amp is fairly healthy sounding. No ghosting. A little bit of hum that I will track down, but no odd buzzing or grounding issues that I can detect.
I will remove the death cap/polarity switch and rewire the mains/power switch to fuse the hot line instead of neutral. And I'll clean up the wiring.
...I might also have some interesting mods once it's fully restored. I have no need for a stock Super Lead and something interesting to note is the 4th preamp tube cover that is screwed on, not riveted *hint hint* *wink wink*.
A small handful of the original solder joints look to have been reflowed. Mid pot is an older Alpha replacement. The 0.68uF in the third stage looks to have either been added or the original was replaced. And the input grid wire on the third stage was replaced with shielded coax for a "hot shield" mod. There does seem to be a lot of noise coming from this part of the circuit. Tapping on the second stage's coupling cap and/or the treble peaking cap produces a loud pop/bang.
A few of the resistors measure too high or too low and might need replacing if I want to nit-pick (like those carbon films in the B+ line). The 220K PI grid leak/output resistors also measure a bit off for comfort. One measures 208K and the other is also off but I don't remember the exact value.
Will replace the cement screens with Welwyn 7W.
The stubby 0.1uF presence cap and Wima 0.1uF in the PI are both original. But looks like Marshall might have run out of 400v 0.1uF caps and used these instead. I might leave them in since they're original, but I kinda want to replace with the period-correct Philips to satisfy my OCD.
I plan on re-capping the bias caps at the very least. And possibly the filter caps since they're so old, although they show no signs of wear. The amp is fairly healthy sounding. No ghosting. A little bit of hum that I will track down, but no odd buzzing or grounding issues that I can detect.
I will remove the death cap/polarity switch and rewire the mains/power switch to fuse the hot line instead of neutral. And I'll clean up the wiring.
...I might also have some interesting mods once it's fully restored. I have no need for a stock Super Lead and something interesting to note is the 4th preamp tube cover that is screwed on, not riveted *hint hint* *wink wink*.
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