Dear Colin,

I am pleased you like the content of my old site. I am sure a lot of it will reappear as time goes bye.

Here is the Tweaker circuit. Earle was happy for me to publish it. It is being revised all the time. My mono amps will have some changes to the one shown here. I have only shown one power amp channel to help cut down on image size.

Valve sockets arrived today so one step closer to starting.

Howard

I have started a page for this project. I have my card model plus Earles pictures of the original being built

Have a good weekend

Howard

• Tweaker construction page

KT88 in Ultralinear mode -3db 22hz to 45khz. -6db 15hz to 67khz.
Maximum power 16 watts. Hum 1.2mv. S/N 102db hum removed.

The signal to noise is very dependent upon driver valve choice. The best result was from a NOS Sylvania Angle plate 6sn7. A Chinese no name 6sn7 returned similar S/N but frequency was down -3db at 13khz.
One of my favorite valves, a Sylvania 6SL7WGT was quite noisy with a S/N of 67db, go figure.

EL34 triode mode -3db 15hz to 41khz and -6db 11.5hz to 62khz.
EL34 UL mode -3db 23hz to 52khz and -6db 16hz to 76khz.

The installed valves were Valve Art 5AR4, Sylvania 6SN7 angle plate and new Valve art outputs.

I've been working on a (shock horror) push-pull amp. The transformers I have wound using the same technique I developed for the SE iron. They test very impressive out of circuit. -3db 7hz to 58khz. In circuit they should perform similar as the bias current is self cancelled. The top end may go a bit higher due to the ul taps.

The attenuator xformers are coming along as well. I'm happy with the test results and will now work with taps. I plan to have only 12 taps with a +3db boost tap to add a bit of gain to a passive pre.
Cheers. Earle.