Recent content by xenrelic

Hi Mike, The 47k is the NFB resistor and the presence I'm using is the 25k linear pot setup with a 4.7k resistor to ground and a 100nF cap, like on the JCM800. A standard JMP Super Lead 5k pot setup without the 4.7k resistor will do as well. The feedback mod adds some fixed resonance on one...

I've had a lot of problems with tubes from Nesstone since Craig seems to ship stuff that fails grid emissions tests sometimes. I highly recommend testing them first in a solid tube tester and making sure they are matched and do not have shorts or grid leaks, which seems to be a common occurrence...

Yeah, I'm out in the San Jose California foothills.

The master works just a like a type 2 post phase inverter master volume, except the ground lugs actually go to ground instead of a bias splitter junction since this is a cathode biased amp design. The sound and operation of it works the same though. In the video we have the master volume on a...

Hi Bart, yeah I can do that. What material would you like? There's several vintage Phenolic material choices now along with the modern G10 FR4 in various color options like Red, Black or Natural Green like in the previous build posts above. This is '65-'68 era Paper Phenolic: '69 Linen Phenolic:

Here's the latest SV20H hand wired builds. The new custom DI and Transparent FX Loop boards turned out really good.

Hi Scott, I am and yes those are the current prices for the hand-wired modification if you purchase an amp new or used and have it sent out to me here in California.

These amps really shine if you add a 2.7k resistor in series with the 10k power node resistor that feeds the preamp to drop the voltage from about 390v to 370v at the Phase Inverter node. The stock 390v is a bit too much and can make the amp sound fuzzy or unfocused. I added a push pull pot in...

I've been building the base model including the DI and the Custom FX Loop for $1500. The fully loaded ones with all the extra mods I've been building for about $1800.

This doesn't need to be in tech corner, I was just explaining why the mods were done per the questions asked. We're not trying to repair anything or get tech help lol. We're talking about the rig here.

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...

If you guys dig the Marshall SV20 amp, here are a couple that were gutted and hand wired with a custom fx loop, an added post phase inverter J-taper master volume and some other mods like a dual negative feedback loop circuit switch and push pull high gain mod with a bright cap selector push...

Peter's '74 had a ton of rad stuff going on after we were done with it. Splawn had gutted it at one point and replaced the power transformer, but I guess it crapped out on him and Peter wasn't really happy with the overall sound of it, so while I was looking at it for repair I let Peter borrow a...

Awesome. Whoever bought that from Peter got a deal! Here's a similar mod that was done to a Marshall Origin 50 if anyone wants to hear what the high gain channel sounded like.

Cool demos!