I thought it sounded great but I'm not sure why you just wouldn't go with a completely different amp if you're going to do that much to it. I forgot to ask who did it?
Since there were no hand wired 20 watt plexi amps available through Marshall, a friend of mine found a deal on a used SV20 and asked if I could hand wire one for him. I thought it was a weird idea, but just for shits and giggles I was like alright let's try it and it ended up sounding really great.
I posted about the first couple of prototypes we made and then I started to get a bunch of people interested in them, so I kicked things up a notch and made some custom boards that would be easy drop in replacements.
At first I didn't think there would be much difference between the stock and the hand wired version, but the sound comparison in person between the two is pretty crazy. The stock SV20 is already pretty great, but the hand wired version makes the PCB version sound like a toy and so we concluded that it was well worth the effort.
Considering the Marshall hand wired stuff is about 3-4k now, buying a used SV20 and upgrading it is actually cheaper, so it made sense to go for it. Plus the current hand wired line up doesn't really sound like the old ones, so doing our own build insured that we'd get a better quality sound than current Marshall production offers.
Also the op amp buffered fx loop isn't the best on the SV20, so we opted to install an LND150 buffered fx loop instead and it works much better.
Here's the stock chassis:
This is the first prototype we made using a 1974x style turret board, early prototype di and fx loop boards:
Second prototype which has a JTM voiced normal channel, high gain push pull but a boost push pull on the other pot instead of the bright cap selector. First amp with the new board layout, new power supply layout and newer prototype smaller di and fx loop boards:
Since those first two builds I've really dialed in the layout to make the conversion a lot less time consuming to implement.
