This year I bought an ots(non-HRM).
It was an april model, so I did all the Zucker/Learner/Ayan mods.
I was fairly happy with the sound but I knew it could be better,
based on several clone soundclips I heared with the same specs.
I did 3 things that made a big difference in sound;
1. the bass cap is .0012uF; I changed it to .001uF: more detailed bass reponse.
2. Adding 2 parralel 47uF filter caps to the existing 100uF filter caps makes the
onstage volume bass reponse more lively.
3. Last and most important: In original dumbles the filament wires are floating from one tube socket to another.
Lead dress is done according to that method.
In Ots the filaments are located against the back of the chassis
I didnt want to solder the filament wires again because getting those filaments back again is a pain in the ***!
So I decided to experiment with the wires coming from the pre amp tubes. Especcially the wire coming from pin 3(cathode).
In original Ots from factory this wire is follwing the dumble layout, but also sitting on the filament wire.
When putting the cathode(pin 3) wire floating 1 cm above the filament wire, on both V1 and v2, there is a massive
change in sound. The overdrive seems to be the most affected. It has a really thick tone now and less fragmented.
At first, I thought I auto-suggested it. So I put the cathode wires back,sitting on the filament wires. But there was again that fragmented lead tone.
It's just unbelievable that such a funny little thing is making such a big difference. Bandmates and even my wife noticed the difference.
Hoping you OTS owners can benefit from it
Greetings Erwin