Second amp rebuild, a Marshall 14Watt 2203 into a Superlite design

T-Rex

T-Rex

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Oh I was on a roll. Decided my 14Watt Marshall 2203 clone 6V6GT had more gain than I use, and after good luck creating the Bassman, I decided to have a do-over on this amp head too. I went way back to the start of my amp building. I had self taught myself many years ago how to build a 18watt Marshall variant by learning from the 18watt.com site. Decided to change this into a morphed version takeoff, (design from the 18watt site) of the Marshall 1974 amp. I think the 1974 was only a two year run @ 1966.

Did the same thing as the Bassman. Did all the mods with the turretboard in place. Converted that 18watt amp Superlite design version into a 6V6GT version with a full tone stack. Nice cleans. A Marshall clean is just something different from every other clean amp. Crank up the Overdrive and man what a nice tight crunchy tone ! I can finally rest on getting those "got to have this tone thoughts" out of my head. It was a fitting end to my amp building journey that I started 14 years ago. Who says you cant go back home ?

Its paired with a 1 x12 cabinet with a Marshall Vintage 30 speaker, the real deal. Pics below.

https://imgur.com/a/7GD3rw4

https://imgur.com/a/Bz2BFgm

https://imgur.com/a/tsdT9Ip

https://imgur.com/a/D7XwMQd

https://imgur.com/a/J1eEcdQ

imgur.com
 
Very nice as usual, Terry. Looks like the circuit is cathode biased with a 300 ohm resistor and a 1000 uF cap. Is it normal for such a large value on that cathode cap?
 
T-Rex said:
Here is the "as built" schematic with voltages.
Click to expand...

Nice work - sounds like a cool amp. The standby switching is problematic though; if you engage it with discharged caps and the rectifier already conducting (at temperature), the empty filter cans present a near short causing a massive current spike in the 5AR4. That will often kill rectifier valves prematurely.

If you place the standby switch after the filter caps, the inrush is no longer problematic. Obviously, you don't inherently *need* a standby switch, but I do see use cases for them - mainly swapping speaker loads on the fly in my case.
 
It's your amp, your call. Provided the standby switch is just left in the 'play' position, it's not a problem either of course. :yesway:

FWIW, VOX and Marshall have made this error in the past, probably more. Marshall to this day use this arrangement in the JTM45 reissues.
 
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