WHat Germanium Transistors??

[Derrick]

Hello, are there any germanium transistors that are good for most basic fuzz circuits and pretty cheap or do you really have to exp. with diff. ones?  Are there any that are kind of like a "one can do it all" type of germanium transistor I can buy?  NTE150?  Also, who is the cheapes  for USA sales?  Mouser?
THANKS!!

[petemoore]

Matched, tested documented Ge transistors from Small Bear Electronics ! Mine came with resistance values for FF and TB circuit biasing, and work great.
 I've had good luck with NTE158's, but they're pricey and 'dicey'...see GEO Technology of the Fuzz Face.

[Derrick]

I don't recall GEO recomending any specific germanium transistors.  If I understand this correctly, hfe is the only thing focused on in selecting a GE transistor for a fuzz circuit.

*Are there any specs other then hfe that determin wether a germanium transistor is sutible to use in a fuzz circuit?

*Are there any specs other then the hfe of a GE transistor that effect the characteristic/sound for a given fuzz circuit?

THANKS!!

[GreenEye]

I tried a NTE101 with Aron's Hornet and didn't like how it sounded at all.  However, I recently used it as a diode, and it kicked ass.  Really different sounding that a typical germanium diode.

[petemoore]

I don't recall GEO recomending any specific germanium transistors.  If I understand this correctly, hfe is the only thing focused on in selecting a GE transistor for a fuzz circuit.

*Are there any specs other then hfe that determin wether a germanium transistor is sutible to use in a fuzz circuit?
 <<<YES, there IS.
For best FF info assimilations, print out GEO 'technology of the FF' and reread that a few times, if the equations are hurdles, go around them till you figure out how to get over them.

*Are there any specs other then the hfe of a GE transistor that effect the characteristic/sound for a given fuzz circuit.

THANKS!!

This is My version of GEO Technology of the Fuzz Face...but it's quite wandery, less concise, less accurate, and also less complete...there is also Twenty or so Tons of FF info for the searcher...but the GEO article has stood unchanged AFAIK, so, for the FF info searcher, there is Twenty or so Tons of info available, tho it may not have what you need, as far as choosing transistors for use in a Fuzz Face, I recall this is the ony place I've seen to get that...the in depth article is amusing in places, submerged in equations in others...[if you're not good with equations, I'm not, this might be a good incentive to get good at them...I could figure it out, I'm just lazy, and don't really know where to get 'just that which I need'...or it's more than I'm knowing enough about how hard it is to start searching, or asking about what to read, then not read it   ]
 Transistor testing jig...

[Derrick]

Uh?

Well, how are other board members choosing what GE transisters to use for various projects (not just the FF)?

[petemoore]

Feast your eyes on THIS:::
 GEO "Technology of the FUzz Face"...That's:
 GEO...."Technology   Of the Fuzz Face"!!

[mojotron]

Uh?

Well, how are other board members choosing what GE transisters to use for various projects (not just the FF)?

The FF and Ge parts - a complicated subject... The selection of Ge parts only starts with Hfe matching...  each type will sound different.... the paper "The Technology of the Fuzz Face" will get you started figuring this out.

One thing you'll notice on Si compared to Ge parts is that Si parts sound more alike than Ge parts. This is because of the differences in production and purification techniques. The result is that different transistors have differnt parisitic loss in the device and that affects the sound greatly. Also, the parasitic loss changes with different amounts of current and heat. On to of this, there is no way to tell if the parts you buy will actually be worth using....

In short - Ge parts suck to work with! The pay-off is worth it though - they make great warm sounds.

You really have to try some recomended ones and see what you like - each part is going to have it's own sound - this will likely cost you a lot of money (100's of $), or order 1 pair from Smallbear and see if they'll work for you....

I like the combo of NTE102 and NTE102A. The NTE102 is too edgy (but has a lot of gain) and the NTE102A is too warm sounding, to my ears the combo is just right to duplicate the sound of the - impossible to get - NKT275. But, this combo is much quieter and can be used in more circuits than just the typical fuzz. The down side is that if you order 10 of each for about $70+ you will end up with maybe 4 or 5 combos that you can build with and about 5 transistors that can be used for other things. So with the yeild I have found, the effective cost of these is 2X what most people already consider expensive.

I really liked the NTE158 as well - but, use a smaller output cap to ballance the warmth of the NTE158....

So, I'm working on modeling a Ge device with some experiments - I'm wondering what other's have found using the piggy-back fuzz circuits (2 transistors back to back with the 2nd acting like a diode...) with Si parts???

That seems like it has some promise to solve this issue.

...Or you can just get some parts from Steve @ smallbear for $10/pair - what a deal!! I just don't know how they sound... but I found that if the transistors are a little too edgy, a larger output resistor or cap can be used to compensate.. Hope this helps...  

[R.G.]

*Are there any specs other then hfe that determin wether a germanium transistor is sutible to use in a fuzz circuit?

Yes. Leakage. One of the main points of the "Technology of" article is that you have to measure leakage as well as gain, and learn to separate the two things because the commonly available gain measuring devices confuse the two, assuming all devices are zero leakage.

*Are there any specs other then the hfe of a GE transistor that effect the characteristic/sound for a given fuzz circuit?

Yes and no. Are there other characteristics that affect the sound? Oh, my yes. Are they specified? Unfortunately, no. What affects the sound is the imperfections, and datasheets were always used at least partially as a touting of how perfect, not imperfect, a device is.

Piggybacking silicon produces the closest sound to a well-selected germanium device that I've found. I originally proposed piggybacking as a way to get the gain down, because silicon transistors are uniformly high-gain these days. Piggybacking wipes some of that high gain away. Adding capacitors to lower frequency response helps some more. There's probably some tricks to play with diodes to throw kinks into the device characteristics that I haven't found yet. But someday I will.

If you want to play with Golden Age fuzzes made with germanium, you necessarily have to select transistors. I tell you three times: there is no way to interpret specifications and datasheets for germanium devices to get good sound. The individual device varies too much. You must select each individual device. The datasheet specifications will only select candidates. Germanium availability being what it is, any device with a datasheet Bvceo of 16V or more, 1W or less Pd, and hfe including 100 is a potential candidate. That's about as good as the specifications get. From there on, do the hfe and leakage tests, and select by ear for lower noise.

But that's what I said in the Technology page.

[Derrick]

Thank you RG and Mojotron!

any device with a datasheet Bvceo of 16V or more, 1W or less Pd, and hfe including 100 is a potential candidate

OK.  So, in theory... if two GE transistors of different make, model, whatever, had the exact same specs, should they sound the same in a given circuit?  In other words, if these specs were exactly the same for to randomly found GE transistors like an RCA AZ204 and a Phillips OC-199... chould I expect them to basically have the same sound/characteristic?

THANKS!!

[Paul Perry (Frostwave)]

OK.  So, in theory... if two GE transistors of different make, model, whatever, had the exact same specs, should they sound the same in a given circuit?  In other words, if these specs were exactly the same for to randomly found GE transistors like an RCA AZ204 and a Phillips OC-199... chould I expect them to basically have the same sound/characteristic?

If they had the same characteristics IN ALL WAYS, then they would be the same transistor (though we are getting into philosophy here!)
BUT, just leakage & gain & voltage drop at particular currents aren't everything, there is frequency cutoff as well, which is dependant on junction geometry, so that might make a difference also. lthough the GE transistors all covered the audio band, when they are in a circuit it could make a difference (at least for you young kids with ears!)

[Derrick]

So does that mean that it's not so much a matter of wether you use an NTE 102 or a NTE 102A... it's more a matter of what the specks are for the particular transistor you happen to be holding?

[petemoore]

Actually No...
 If you're holding it, the specs are probably quite different than they would be with that tranny at room temperature.

[Derrick]

Pete, you're quite a useful guy to have arounnd this BBS :roll:

[R.G.]

As I was told by a fully-grown EE while I was just an engineerling:
"Specs are what the manufacturers want you to believe the devices they sell will do. How it actually performs depends on what they really send you. If it's not a match to their specs, you can get them on the phone and call them liars, which doesn't help your design at all."

Specifications are limits, sometimes one-sided limits. The device you actually get may - or may not - live up to the spec. There is no substitute for measuring what you get with old germaniums. The device number means almost nothing within the limited constraints of effects. Measure the devices you get, or you're going to get 2/3 to 9/10 useless devices.

[Ben N]

Pete, you're quite a useful guy to have arounnd this BBS :roll:

Do I detect a bit snideness there?  If so, it is as unnecessary as it is misplaced, as it is unwelcome.  Aside from issues of basic civility (something Peter and Aron have worked hard to maintain, and most people here are quite sensitive to), actually Pete IS quite a useful guy to have around (once you tune in to his unique wavelength) since he has built a lot of the stuff we talk about here, and is always willing to share his experience.  In this particular case, had you paid a little closer attention you would have realized that Pete was just cueing you in to the fact that germanium transistors are quite temperature sensitive.  So if that kind of contribution is not to your taste, just don't say anything, ok?

Ben

[Derrick]

I am aware of this already, but my question is different...

If you forget about what the package or engineers say the specs are, I'm wondering if I can expect two totally different GE transistor designs to sound very similar if their specks both drifted enough towards one another to meet in the middle.  Another words, if an OC-75 and an AC-128 drifted (or had bad enough tollerances) close enough to one another, would they sound the same and have the same basic sound characteristic if Bvceo, Pd, frequency range, and hfe were the same?

[Alpha579]

there wouldnt be alot of difference, but people with better tuned ears will tell you otherwise...    

[Peter Snowberg]

I was going to say something, but Ben said it perfectly:

Do I detect a bit snideness there? If so, it is as unnecessary as it is misplaced, as it is unwelcome. Aside from issues of basic civility (something Peter and Aron have worked hard to maintain, and most people here are quite sensitive to), actually Pete IS quite a useful guy to have around (once you tune in to his unique wavelength) since he has built a lot of the stuff we talk about here, and is always willing to share his experience. In this particular case, had you paid a little closer attention you would have realized that Pete was just cueing you in to the fact that germanium transistors are quite temperature sensitive. So if that kind of contribution is not to your taste, just don't say anything, ok?

Ben

Pete is an asset and I got a good chuckle when I saw his response about holding devices and spec drift.

[Derrick]

Pete, you're quite a useful guy to have arounnd this BBS :roll:

Do I detect a bit snideness there?  If so, it is as unnecessary as it is misplaced, as it is unwelcome.  Aside from issues of basic civility (something Peter and Aron have worked hard to maintain, and most people here are quite sensitive to), actually Pete IS quite a useful guy to have around (once you tune in to his unique wavelength) since he has built a lot of the stuff we talk about here, and is always willing to share his experience.  In this particular case, had you paid a little closer attention you would have realized that Pete was just cueing you in to the fact that germanium transistors are quite temperature sensitive.  So if that kind of contribution is not to your taste, just don't say anything, ok?

Ben

Pete, I dont know where "tourist Mecca" is, but maybe you are in a different part of the world then the USA where you may not understand that when we say "get a hold of" something, it menas we have in our possesion.  If you really think that I meant I'll be holding my GE transistors whenever I use them, then I'm confused.  Lighten up Ben.  Please, I know what Pete meant rearding temp effects on GE.  That clearely wasn't what I was asking, and Pete was being a smart ass.  I don't apeaciate it myself.  I think my reply was pretty civilised.  If that was so bad, then you must have a very hard time of it.  It's not my responsebility to tune into Pete.  Too many times on this board and others, when someone like Pete relies with a smart ass comment like this, questions go unanswered.  Whatever...