Re: 1n34a diodes

Posted by Beaker on May 27, 2016; 10:22am
URL: http://guitar-fx-layouts.238.s1.nabble.com/1n34a-diodes-tp30980p31035.html

"Sorry, I see now. But what do you make of the high (for a Ge) Vf?

I just looked at a datasheet for an 1N34a, and it says the "maximum" Vf is 1 volt. But I was under the impression from various articles that they generally drop .3 v or less.

Color me confused?"

You have answered your own question there Jack. If the datasheet says the max Vf is 1V, that means they can measure up to 0.99V and still be considered to be within specified tolerance, and therefore fit to pass the manufacturers inspection department and out for sale.

So you could easily buy two batches from different sellers and have one batch measure an average of 028V (for example), and the other batch average 075V.

Both batches are within specified manufacturing tolerance, so both batches are "good". One fits the norm, one does not, but it does not mean you have bought fakes or duds. Will they perform and sound the same in your pedal? Unlikely.

It's just the inherent variability of Ge components, which is why they were replaced by silicon alternatives. Silicon parts were more far more consistent, far less sensitive to temperature changes, far less fragile and ultimately, cheaper and easier to produce. And they were smaller to boot. Talk about a win-win situation.


To answer your earlier question about Soviet era Germanium parts, I'm afraid it's not that simple. They made some truly fantastic Ge transistors and diodes, and for far longer too - right up to the mid/late 80's, and were mostly intended for military use. (I believe one of the reasons was that Ge parts won't fry under an massive electro-magnetic pulse (nuclear bomb) attack like silicon components would.)

Unfortunately they had their own design, manufacturing and end-use criteria, so are not simply their versions of once common Western parts. Therefore it's not feasible to say "Soviet diode x is equivalent to Western diode y.

What you can say though, is that if your layout specifies a 1N34A, try a D9V for example - or a D311, or others. I can guarantee it will sound good.

There's a massive sticky thread at the top of the Open Chat page titled " Great Jumpin' Germaniums". It's worth a look through as it collates our experiences and experiments with these Soviet parts.