Orange Squeezer question

[v00d00blues79]

i'm in the process of building an OS and i have a question about the 1n34 Ge Diode thats specified.  Can i use a 1n400x diode in its place if i don't have a Ge one?


Thanks,

Andy

[petemoore]

Ge I think is needed there, Ge transistor would work.

[v00d00blues79]

i went ahead and soldered in a 1n914 instead of the Ge diode and it seems to work ok.  What would the difference be using Si instead of Ge?

Thanks,

andy

[Paul Marossy]

A 1N100 is a fast switching Ge diode. A 1N914 is a fast switching Si diode. Though made of different materials, in terms of function in a typical guitar effects pedal, they're pretty much the same thing as far as I can tell.  

[Mark Hammer]

The hoice of diode determines, to some extent, how much envelope signal is hitting the FET.  In essence, it is almost equivalent to adjusting a DC bias on the envelope/sidechain.  A germanium diode will take less away from the envelope than a silicon diode will, which will take less away than an LED will.

Depending on the thing being controlled by the rectified envelope signal, and how much you can either: a) adjust the sensitivity of the thing or b) adjust the gain of the envelope follower, choice of diode may make little diference.

In the case of the OS, a 1N914 or 1N4001 will essentially result in less compression overall, assuming no other changes to the circuit, because it takes almost a half volt out of the envelope signal.  On the other hand, there IS the trimpot (which could yield LESS compression from a 1N100 than from a 1N4001 if you tweaked it "right"), and there is also the op-amp gain stage, whose gain can be changed (and whose gain I recommend making variable, as in the schem I had posted over at GGG).  What this means is that if you have no other choices at the moment, you CAN successfully use a 1N4001.  My advice, however, would be to hike up the gain of the op-amp a tad.  E.g., maybe a 270k feedback resistor might be called for.

[v00d00blues79]

After giving it a run at practice last night i did notice that it bumped the signal up like a booster and my sound did seem to sustain longer so i can only assume that it is working, but when time permits i will be replacing the 1n914 with a 1n34a or 1n100 when i place my next parts order.  I built it mainly to play around with the Blue Box clone i built... I've never played through a compressor much less an OS before so i don't know exactly what to expect from it. =)

Thanks,

Andy

[Mark Hammer]

What you should expect from it is that when you slam a chord, there won't be a huge difference in loudness.

[Paul Marossy]

In the case of the OS, a 1N914 or 1N4001 will essentially result in less compression overall

Interesting. So what is the controlling factor here? The forward voltage of the diode?

BTW, it seems to be a pretty subtle compressor to me. I mean it's not like some that I have used that are very obvious when switched on...

[gammamu]

In the case of the OS, a 1N914 or 1N4001 will essentially result in less compression overall

Interesting. So what is the controlling factor here? The forward voltage of the diode?

BTW, it seems to be a pretty subtle compressor to me. I mean it's not like some that I have used that are very obvious when switched on...

could you increase the compression using 2 Ge diodes in parallel.

forgive my ignorance, as i am a bit unclear still on diodes.

[Mark Hammer]

could you increase the compression using 2 Ge diodes in parallel.

forgive my ignorance, as i am a bit unclear still on diodes.

Ignorance is always forgiven (especially, I hope, when it is my own). As far as I know, parallel diodes will not do what you suggest.

Part of the "subtlety" of the OS is that it has a reasonably fast recovery/decay time, and acts a little more like a limiter in that respect.  My guess is that with a much longer decay (stick in a 100uf cap instead of the cap to ground after the diode), it will start to sound more like some other units in its "feel".

[v00d00blues79]

i just bought a lot of 25 1n34a's off of ebay for $4 plus shipping.  So i will be able to drop one in and see if i notice a difference.