Boost Yer Germaniums

[modman]

Hi all,

Have been overfocussing on a single stage guitar booster designs and managed to come up with a very basic setup to use Ge transistors in such a booster. In the sense that it doesn't just boost the treble like the Rangemaster.

That's why in this as yet still stripped down version, the conponent count is minimal: 3 caps, 1 resistor, 1 pot, 1 transistor.

The simplicity of the thing stuns even me, and it seems that just dumping the voltage divider is the trick.

You could probably put some resistance across Base - Collector, but haven't tried that yet.

Of course the ground doesn't connect to the output network, just to the pot and cap on the emitter.

C1 = .022uF

C2 = .047uF or higher

C3 = 47uF

R1 = 100k trimpot or appripriate resistor to bias collector voltage at 4,5V for the optimum transistor operation. Putting the bias over 5V will influence your distortion, make it shred a bit more.

R2 = 5K gain pot

more detailed report on my blogpage:

http://modman.blogdrive.com/archive/37.html

thanks for reading this.

j

[modman]

wow i would have expected that at least somebody would say something.

I did make a very low res vid of the basic circuit in action.

but will be cleaning it out with a tone control and more soon

[Samba Pa Ti]

its very cool and simple, im wondering what other transistors can you use ?

ac128 for instance ?

[modman]

its very cool and simple, im wondering what other transistors can you use ?

ac128 for instance ?

hi there,

AC128 is a PNP transistor, I used a NPN in my setup, because PNP uses positive ground.

This means: if you use a PNP transistor, you'll have to connect the ground where the +9V now is and you will have to turn the electrolyte C3 around. Positive side of that cap touching postive ground

It's a boosted overdrive and R1 determines the voltage on the collector. Optimum operation for the transistor is 4.5V but putting it higher will result in dirtier sounds still.

mm

EDIT: I finally made some decent soundclips with my BF Super Reverb. Recorded with SM58 mike, no processing.

Clean setup: Strat's neck PU, Texas Special

Download GermaniacClean.mp3

Boosted: Gradually turning the gain up, it turns out that it clean boosts and distorts at the end of the taper. Before the final riffs you can hear me putting the mike back a bit

Download Germaniacboosted.mp3

Edited April 30, 2007 by modman

[Samba Pa Ti]

ive used ac128 (pnp) transistors is positive and negative ground, so wouldnt it work either way ?

Edited April 30, 2007 by Samba Pa Ti

[modman]

Of course, I was just stuck in my head with the problems inherent in negative ground Fuzz Faces (oscillations etc). Probably in this design you won't have that problem using PNP on negative ground.

Will try it myself once I some time later today. Damn, you really woke me up. thanks

Have so many PNPs that I put aside because of this issue, should have tried really.

[modman]

Here are some more samples of the basic circuit.

I did install a master volume, so I was able to max out the gain.

The three different samples are with full gain, at different bias voltages: 3,5V 4,8V and 6V. They're on putstuff, so you'll have to click three times to get the file

Download Germaniacbias3_5.mp3

Download Germaniacbias4_8.mp3

Download germaniacbias6.mp3

j