Jaap Knoppert Tube amps for guitar

Zabs yellow cab! A high gain amp with three preamp stages and a single ended power amp. As you can see the amp runs on only 2 tubes: a 12AX7 and a triode/pentode ECL86. The amp is based on the Hi Octane but it has a one knob tone control which acts like a sort of mid control. This gives the amp a sound range from Marshall to a sort of Vox like sound. I tried all kind of tone controls but this is my favourite for this amp. Also because it gives a bit more signal and overdrive to the power tube.
You can use just two preamp stages or all three. The third one can be switched in for more gain.
I used a one star grounding system and the amp is very silent. At first it hummed and oscillated but I found out that two things were crucial: 1. grounding the mid pin of the noval socket of the ECL86 (stopped the oscillation) and 2. the reference at the catode of the powertube for the filament (no more hum). The Siemens ECL 86 pentode runs at 260V into a 10K primary OT. Output about 3 Watt. The 12AX7 is by Tung-Sol, I like that tube very much.

Dimensions (inches): 12.2 (w) x 5.9 (h) x 4.3 (d)