Germanium Transistors!

[Voodoorider]

Hey guys!

I'm building a fuzz pedal but I'm having trouble getting my head around which transistors are good and which aren't.

I've ordered a bunch of AC128's which i know are a good start for a good price but i wanted to get some NKT275's although they are really quite expensive at almost £5 each at cheapest!.

can anyone suggest a transistor which is near equivalent but cheaper (I have seen NKT274's that are cheaper but what's the difference :/ ??

Or even a different transistor that will provide a smooth hi-gain in a Fuzz Face style circuit?? I think a gain rating of around 110-150 would be about right? I'm only assuming the gain rating means the higher the number the more the signal would break up.

There are just so so many and they are quite confusing Any help would be most appreciated!


Cheers,

Garry

[R.G.]

Unfortunately, you cannot tell by the part number printed on the part whether it's any good for your Fuzz Face or not. This is an old, very well plowed field in pedal making. Go read Selecting germanium transistors for Gain and Leakage for your Fuzz Face Clone at geofex.com.

Bottom line? NO transistor is good until proven to be so by either testing or listening test.

Worse yet, the sleazeballs have noticed this and are selling counterfeits of the highly desired numbers - like NKT275. Worse yet, the sleazeballs will buy quantities of possibly-good types, select out the good ones, then sell the picked-over leavings as good. Back when I was selling selected germaniums for FF clones, I typically got 1/3 good ones. I used the leftovers for germanium diodes but not everyone is that ethical.

If you're making one or a few pedals for yourself, buy them from a reputable testing service, like Small Bear Electronics. If you're going to go into making pedals as a business, be prepared to learn a lot of things like this the hard - and expensive - way.

[Steve Conner]

R.G. is right, shopping for germanium transistors is like shopping for NOS vintage sushi. Except you don't get to smell it before you buy.

Why not try silicon, I heard they can sound just fine with some bias tweeking.

http://www.google.co.uk/search?q=silicon+fuzz+face

[Voodoorider]

So there is no kinda standard ball park transistors that would be used in a simple fuzz distortion? like my dad has some 110 gain rating transistors and he said they have a leakage of 80 i think it was (he has tested them, he's well into diy audio equipment). They sound just the thing, but they are modern, silicone i guess, would it be worth trying them? i know the "try it and see if it sounds good" method but there must be rough rules to it?

I'm aware of all the dodgy clones from what i've read, it just seems so limited to be a choice of 3 or 4 different transistors out of the hundreds you can get.

Cheers

thank you both for your help by the way!!

[Mark Hammer]

One of these days, I need to scan my old SAM's transistor cross-reference book from the 70's, and post it (thank goodness it is from the old days when there were fewer devices in the field, even WHEN you count all the HEP, radio Shack, and RCA "universal replacements"). It will give you an idea of just how many different subs there are for other trannies.

Of course, being a nominal sub, and being a functional sub are two different things. And when it comes to tone and the qualitative aspects of distortion, very often even a viable transistor (i.e., no leakage problems) of the exact same number type (e.g., AC128) is no guarantee of achieving the same audible outcome.

There are posted lists of candidate germanium transistors around, and these are reasonable places to start. But as RG wisely notes, a number on the package is no guarantee of anything anymore. I've been fortunate to be able to buy bubble-wrap cards of unsold Japanese GE transistors from a now-defunct surplus place carrying VERY old stock (not on-line NOS peddlars). Of course, while the vendor in this case was not hustling the buyer (these are "variety packs" originally packaged by the manufacturer), neither do they have any idea whatsoever if the devices are on or off spec at the time of sale.

Ultimately, the transistors you want are the ones that your meter, and eventually your ears, tell you are suitable. It would be nice if one only needed to call up Mouser, buy a tranny, and stick it in a socket the day it arrives. Sadly, when dealing with technology that is no longer in production, it can't be that easy.

[golmv]

NKT274's

Just to let you know that It's me selling the NKT274's on ebay. They are genuine NOS Newmarket transistors form the late 60's/early 70's. They are the same transistor as the 275 in all areas but are from the higher end of the gain range. HFE range from 80 to about 250, they are low leakage and sound great. No diodes! I have about 3000 left out of a batch of 5000 and they are selling fast. They are cheap as I need the cash for Christmas, they will go back up to a sensible price in January.

Stev eH
golmv on ebay

[dumbassbob]

thanks for reply nice to see honest seller