Which Ge Transistor in SD-1

[RobbieD_216]

Hi, Being new to pedal mod culture, I have a question. I am in the process of organising the Keeley 5StarGe Mod on my SD-1. What I want to know is is how do I know which Ge transistor to use? I was going to get it from smallbearelec.com, but didn't know which one I needed, or what the main difference was. Thanks for your help.

[petemoore]

Transistor ?...the SD-1 transitors IIRC are just buffers, and Ge's there probalby8 wouldn't be 'desirable'...
 The clipping diodes in an SD-1 though can be swapped for GE's, in the clipping position...more grit and less output I'd wager.
 1n60, 1n34...anything that says Ge diode I think.

[MartyMart]

Your talking about using a Ge transistors B & E junctions as a diode ?
Then it doesn't matter if its an NPN ( AC127 ) or PNP ( AC128 ) etc etc
Just make sure its a "junk" one first, if its a good 70 - 140 hfe and not
leaky, then use it in a Rangemaster or Fuzz Face.
Buy a bunch and "weed" out the junk ones for this purpose

BTW: Didn't sound any better than a Ge diode IMHO anyway !

Marty.

[petemoore]

BTW: Didn't sound any better than a Ge diode IMHO anyway !
 Makes sense ... a Ge diode will 'sound' like a Ge diode...lol, you can always measure the foreward voltage threshold for 'better* match, if it's deemed as necessary/

[RobbieD_216]

Hmm, you have hit the nail on the head. How exactly do I go about weeding out a "junk" transistor to be used as my clipping diode? And secondly, what happens if I don't use a "junk" one? Thanks for your help.....

P.S. What would the difference be if I just used a 1N34A? Considering the price difference, is there really that much of a difference in tone?

[petemoore]

You test 'em for leakage and Gain, [see GEO Technology of the FF]
or you get used to sticking 'em in and biasing 'em up on a FF or Rangemaster and see what you get.
 Some DMM's have Hfe checker's but these are not 'accurate' because they don't 'account for the leakage...
 How good they sound tells 'alot.
 A Ge diode will for all intents and purposes do exactly the same clipping job as a Ge diode in a transistors B/E junction, measureing the foreward threshold voltage of the individual diodes..in a transistor or not tells at what voltage it starts clipping in a diode clipper circuit.

[wampcat1]

Hmm, you have hit the nail on the head. How exactly do I go about weeding out a "junk" transistor to be used as my clipping diode? And secondly, what happens if I don't use a "junk" one? Thanks for your help.....

P.S. What would the difference be if I just used a 1N34A? Considering the price difference, is there really that much of a difference in tone?

I think Pete just means don't go wasting good transistors just to use them like a diode...you won't notice any difference if you use a 1n34a IMO (unless you have dog hearing!  )

Hope that helps!
Brian (indyguitarist)

[RobbieD_216]

Yeah, all makes sense now. I was confused as to why someone would use a transistor that was worth like 50 times as much, when a 1n34a is like 40 cents. Now it makes sense....put the junky transistors to good use. I think I might invest in a stack of 1n34a's for future purposes...thanks for the help.