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Using the 6CA7 setting.

Yes

I have a quad of EH 6CA7 that test fine.

My '70 Super Lead and my '71 Super Trem both had their NFB attached to a speaker jack from the factory, as apposed to one of the output taps. I promptly moved both over to the output tap of my choosing, which I prefer. I'd rather not have my NFB change depending on the speakers I use. It's also...

lol the Rosemary thing is hilarious. Rosemary wired the back panel, at least on this amp. That means she wired the impedance switch, output jacks, and fuses. For some reason, people began associating Rosemary with a better quality build throughout the amp, even though she never touched the rest...

Nice find. The glass-reinforced "self leads" of the OT secondary are a dead giveaway as to what OT it has. I believe this amp was a non-North American export. Amps exported to the USA had a polarity switch and four speaker output jacks. This amp has a third speaker output jack added after the...

Ok so for the main resi node, there were two 150uF in series? In parallel? What was the total capacitance for the node directly after the rectifier?

If it's two 200uF in series, it's 100uF total, regardless of the center tap. Merren makes good output transformers. So if it doesn't sound good now, I don't think a different OT will do much. Unless you got a dud?

What OT is in there now? It's a subtle thing. If the amp isn't doing it for you, I wonder how much swapping OT will really do. I did my 5GS mod to two customers' home builds recently. They sounded much drier than a real Marshall.

Nice. That's basically what I'm thinking about doing to my personal 1959T Bay Area Thrash Mod—upping the main reservoir (plate) caps to 100uF+100uF to raise that node from 50uF total to 100uF total. I'm just wondering if the inrush current will stress the PT too much and/or if the charge time...

So what's the total capacitance for the plate node and the screen node?

Your '67 had all the filter caps on the interior, right? On a separate turret board? What was the total capacitance for the first, main reservoir node directly after the rectifier?

If you've already got an older Super Lead, just mod this one. It's a '75 with a PCB, so it's not like it's super rare.

Which 100/100 do you use? I wonder what the time constant is for the 100/100 caps compared to the 50/50. It already takes a good 10-15 seconds for the caps in the stock amp to fully charge. 100uF caps might take quite a while...

I like the higher filtering. 50uF + 50uF everywhere. If not more. Remember that Marshall runs the reservoir caps and screen caps in parallel-series, so even though you have FOUR 50uF caps for each, the total capacitance is still only 50uF. Except for the phase inverter, which gets 100uF.

Most likely. Although I don't know why they wouldn't just use teflon or tefzel wire instead of PVC. No melting. Less work. Less wasted time. Holds up better than PVC too.

Nice!

I'm rather fond of the 5GS mod I've been doing lately. With the right donor amp, it's quite eye opening.

Probably the Uber Ultra