Hybrid RANGEMASTER

[spoontex]

Hello,

I want to build a RANGEMASTER with transistor switch between Ge and Si. I have some germanium PNP ASY27, with gains between 60 and 100 hfe. I was thinking, for the Si transistor something like the 2N3906 or 2N2907. It's better to match the gains between the two transistors?

Thanks.

[mac]

No matching needed, but same gain.
Mpsa92 has lower gain, about 100.
More than 150 and it might clip harder.

When switching you will need to change bias as well. Just tweak the Vcc to Base resistor, or Base to Gnd.

mac

[thetragichero]

my guess is the simplest way of doing the switching is with a dpdt selecting between what is basically two separate rangemaster circuits

[mozz]

3p3t should work.

[ElectricDruid]

my guess is the simplest way of doing the switching is with a dpdt selecting between what is basically two separate rangemaster circuits

+1 this. The reason being that when I built one, getting the bias right was crucial to getting a good sound out of it. If you just switch the transistor, you'll probably have the bias right for one but not the other. Or you'll have to pick some compromise bias point which is ok for both, but not ideal for either. Better to have the two working as well as they can, and then switch between them. After all, it's not like that's a lot of extra parts given how simple it is.

[davent]

For the silicon side you might want to consider the Omega circuit.
http://www.runoffgroove.com/omega.html
dave

[cnspedalbuilder]

Sounds like this is what you are looking for:
http://tagboardeffects.blogspot.com/2019/03/throbak-strange-master.html

[spoontex]

I will put external BIAS, because it's no sense putting internal... I know that the BIAS will change when I switch between transistors.

Thanks!