Dear All,

That's my first thread to the Forum! I just finished my Overtone100 and it eventually runs after some minor problems with the wiring.

I start getting on the nerves of my neighbors. Awesome tone!!!   I have some hum though, so I intend to have a closer look at the heater cables (in my previous amp glueing the cables to the chassis did the trick). Nik already mentioned that shielding of the head shell would help as well.

But now for topic of this thread: I prepared a layout for the 1/2 power mod for the Overtone100 and I thought before tweaking the amp maybe one of the gurus here in the Forum could have a quick look on the attached pdf file.

Looking forward to getting some feedback.

Thanks and cheers,
fm4

Thats some pretty funky wiring.

Basically the Dumble way was to use a switch to break the path to ground for one tube on each 'side' of the phase inverter. As a bonus if you hook a LED and resistor to two of the tubes that will shut them off and make the LED light at the same time.

Following ic-racers suggestion, I tried to adapt the Overtone100 layout with the #124 schematics for the 1/2 power switch (see attached file).

As I am new to the tweaking business and still in the learning stage, I am of course glad about any hints and tips.

Thanks,
fm4

Thanks, ic-racer!

I have built it in and it works well. I am switching to 4 Ohm (Ohm in the 100W mode) when activating the 1/2 power mod.

fm4