pedro wrote: ↑Mon Sep 19, 2022 9:38 am
Yeah. I guess too much additional circuitry kind of takes it further away from the purity of Kens designs
I don’t get too hung up on the purity of Ken’s design. The Express is the partcaster of amps in many ways. The PI is the Fender Tweed/Marshall type with EL-34 output valves, the power supply is very Marshall like apart from the 1K choke resistor. The preamp is very Blackface Fender like too.
The cold clipper in the third stage is like that in a JCM-800.
I don’t think this lessens Ken’s achievement, as he had to work out that this combination would work. Dumble’s Hotel Hog is similar to the Express in that a Fender blackface preamp drives a Tweed PI stage, and yet they are very different amps.
The Express as KF built it was on the verge of control, some more than others. The circuit is pretty straight forward but brings with it a ton of potential gain. My suggestion is always to build it to the original circuit and get it where you want prior to making any potential changes. Careful adherence to the implementation of Ken’s design has always worked well for me. Modifications come after I have established the original circuit is up and running. Those with superior skills and knowledge to mine are likely to have better idea where they want to make changes.
I haven’t found the amp to be on the verge of control, I have found it to be quite stable, though when you plug a guitar in the pickups may squeal or howl due to insufficient wax potting and my guitar howled as the pickup itself was moving in the surround ring.
Yes, the Express circuit amps I have played through are prone to feedback more when using my guitars with either unpotted or light potted pickups. These pickups, at least in my guitars, tend to be in the 6-8k range. When using pickups like a JB or the like which are 16k or greater things can get saucy real quick. I think the beauty of these circuits are the nuances and how one note blooms into several overtones. The clean to mean is real and why I love these amps.
Interesting …. I have found the harmonic content really is quite something.
Even when playing or recording at relatively low volumes, with the treble cap engaged and the treble eq up beyong about 4 i can get easy harmonic feedback at conversation volumes
This is through a thiele 1x12 cab with a celestion 65 I dont really have that with my other amps
pedro wrote: ↑Tue Sep 20, 2022 8:15 am
Even when playing or recording at relatively low volumes, with the treble cap engaged and the treble eq up beyong about 4 i can get easy harmonic feedback at conversation volumes
This is through a thiele 1x12 cab with a celestion 65 I dont really have that with my other amps
Yes and at higher volumes it becomes that much more intense.. No other amp I have does this either, at least to this extent.