What Russian Germanium Transistor to Stock up on?

[fuzzymuff]

Well, I just placed placed an order on a MP39B and a GT308B PNP Russian transistors.  I read these are the same transistors used for the Joe Bonamassa fuzz face.  Damn great price....100 count per bag and about $60 total.  Can't wait to try those out.

[LucifersTrip]

What Russian Germaniums to stock up on that that will work well in a fuzz face and tone bender?  

my experience is that they're not great for either. the tonebenders (except for MKIII/MKIV Q1/2 darlington pair) generally need more leakage than those super low leak Russian ones...Btw, can someone recommend some Russians ge's with gains 80 - 150 with  150-200+uA leakage?

those super low leak ones sound good in FF's but they have a harder sound...not as soft as ones with a little more leakage. Someone said in another thread that they sound somewhere between germanium & silicon

but, they're great for the TB MKIII/MKIV or Buzzaround darlington pair, Rangemasters, and Fuzzrites...and of course, any variants of those along with others that don't need leakage and/or aren't known for a softer, organic sound...

[Thecomedian]

that high leakage you referenced sounds like a typical "bad" transistor.. 

[Arcane Analog]

that high leakage you referenced sounds like a typical "bad" transistor.. 

[chromesphere]

...Btw, can someone recommend some Russians ge's with gains 80 - 150 with  150-200+uA leakage?

Im sure there are others, but so far only ones I have found with 100+ leakage are the GT402B's

[effection]

Maybe I just got a REALLY good batch with my 308A's but I don't think I had a single one with bad specs. I don't remember the typical gain on them anymore, but I honestly don't trust my measurements when it comes to germanium transistors anymore. Just the temperature change from handling them to put them on my DCA-55 is enough to throw them out of whack. I just socket now and if I need to swap out the transistor when I'm done with a circuit, I do so.

I can tell you though that when I went on my sample buying, I liked Russians more than anything and have the tendency to only go that route. I even overpaid for some AC188s because of how much I read them being praised and absolutely hated them. The Russian stuff is a lot more consistent, in my experience. This is even good if you end up buying ones that you dislike, as you know that you dislike that transistor and probably didn't just get some bad ones.

EDIT: And to LucifersTrip... If you want high leakage, go American or European, I'd say.

[fuzzymuff]

What Russian Germaniums to stock up on that that will work well in a fuzz face and tone bender?  

my experience is that they're not great for either. the tonebenders (except for MKIII/MKIV Q1/2 darlington pair) generally need more leakage than those super low leak Russian ones...Btw, can someone recommend some Russians ge's with gains 80 - 150 with  150-200+uA leakage?

those super low leak ones sound good in FF's but they have a harder sound...not as soft as ones with a little more leakage. Someone said in another thread that they sound somewhere between germanium & silicon

but, they're great for the TB MKIII/MKIV or Buzzaround darlington pair, Rangemasters, and Fuzzrites...and of course, any variants of those along with others that don't need leakage and/or aren't known for a softer, organic sound...

Those are the leakage I'm getting with the AC125 transistors I just got.  About one out of 20 I tested was barely under 100uA.  I'm currently putting together a Tone Bender MK1.5.  Would that particular tone bender require a higher leakage like the MK1 or a lower leakage like the fuzz face since it's circuit is so identical to the fuzz face?

[jrod]

...Btw, can someone recommend some Russians ge's with gains 80 - 150 with  150-200+uA leakage?

Im sure there are others, but so far only ones I have found with 100+ leakage are the GT402B's

I have some GT320b that are in that range.

EDIT: Actually, I can't remember if they have the little "b" or a big "B" suffix, but they are GT320.

[LucifersTrip]

that high leakage you referenced sounds like a typical "bad" transistor..  

actually not...100- 200uA leakage is common in vintage ge's and works great in a large variety of vintage fuzzes.  here's a note from R.G. from his classic ge tester FF article:

http://www.geofex.com/Article_Folders/ffselect.htm

"How much leakage is too much? 100uA is common, 200 happens pretty often. More than 300uA means the device is suspicious, and more than 500uA I would say is bad."

edit:

EDIT: And to LucifersTrip... If you want high leakage, go American or European, I'd say.

The whole idea is that the Russian ones are cheap. I was asking for others who are not lucky enough to have a ton of American/Japanese/European ones for vintage circuits that need leakage.

[chromesphere]

Ive been using 300-500ua leakages for a while now with no issues.  I live in Australia, so you know...it gets hot here...40+ degree summer days. Is ambient temperature the concern?
Over 500 perhaps.  I had a few that started with ma's of leakage...1 or 2 ma from memory.  They were stuffed.  The leakage just keep going up in a self-perpetual sort of way.
Paul

[LucifersTrip]

I think the biggest problem with very high leakers is their higher temperature sensitivity...and the other thing fewer people mention...their tendency to fail quicker.

[chromesphere]

I think the biggest problem with very high leakers is their higher temperature sensitivity...and the other thing fewer people mention...their tendency to fail quicker.

Ah!  Just pm'ed someone that exact info! 
So with a 500ua transistor, the <insert fuzz circuit name here> wont sound very good?  Misbaised sort of sound or something else? I haven't witnessed this myself yet...
Paul

[Thecomedian]

More leakage = higher Q point = uneven distortion pattern, perhaps.

With too much leakage, sometimes it's impossible to turn off a transistor. That means that it can't go into cutoff. If you build a circuit to account for the leakage, I'm sure it works fine.

Some good heat sinks or heat dissipation design within the chassis will help out.

its the same way transistors sound better/worse in cold/warm climate. The temp causes more leakage which changes the sound of it.

[brett]

Hi
over the years I''ve bought a range of Russian devices. 308s 313s 311s.
I find it surprising that people have had low hFE and significant leakage with them.
Something that I agree with is the idea that some will sound 'dark'. In a fuzzface, there is a direct relationship between input impedance and the hFE of Q1.
If the hFE of Q1 is less than 50 to 60, it will drain more treble (even more so from high impedance pickups like humbuckers). A HFE of 35 will sound very dark and will need the fuzz control turned up more to get the same amount of fuzz.
I haven't tested all of my 308Bs, but the hundred or so that I've tested from about 20 different batches are very low leakge (~5uA), very quiet, and there's about a 50% chance that you'll get a really good device for a fuzzface or any other circuit that doesn't require a leaky device. Less than 1% are dead and less than 10% have very low hFE (less than 40).
Thank heavens somebody stockpiled these things. They're the future of vintage fuzz.
cheers

[MartyMart]

I also bought a bunch of these about 7-8 years ago.

The 308's I have A/B types and they mostly seemed low leakage and quite decent hfe's from 50 - 150 or so.

The little 309's are just superb = tiny flying saucer type, again I have two versions A&B IIRC.

Most of those tested out fine too and have made their way into a few very decent FF's etc.

I have some MPA 42??? that look like a Canadian mountie's hat and they were pretty useless as a Fuzz device.

I have a handful of VERY large battleship grey devices ( 404 ?? ) which sounded incredibly good, I don't have them
with me - they are in storage so hard to remember the exact numbers !

Best to get some while they are still available, Most of mine did come from Orpheus IIRC.

Marty.

[tjdracz]

Don't really want to necropost but I guess it's better than starting a new topic in this case.
I bought some Russian Germaniums from ebay seller elena8913. Reasonable prices, lots to choose. Below is a link to spreadsheet I made with the transistor measurements. Transistors are MP20B, MP42B an GT402V.
https://docs.google.com/spreadsheet/pub?hl=en&hl=en&key=0AmQTWdBVWu_DdGhTWHpQbXRKSGRGdXJQZVNQMGVQckE&output=html
MP20B are the most usable of the lot I guess and MP42B are bit dissapointing. Datasheet rated at 45-100 they all occupy the lower end of the scale. Guess I will try the leakiest one today in Q1 for Harmonic Percolator and see how it goes. GT402V behave just like the datasheet suggest, although I was expecting more hFE after chromesphere comments and video on youtube. Seems like it's GT402B or GT402E that are higher gain versions. Can't really find either of them on ebay though. The only place that seems to stock B version is this Chinese site http://www.module-igbt.com/electronic-components/transistor/gt402b-ex-ussr-germanium-pnp-transistor-qty-40/prod_38590.html Price seems reasonable so might give it a go sometime later. Also not Russian but close, I should have some Polish germanium transistors in my hands when I go back home for Christmas. They all look quite promising, with gains of 30-140.
Hope anyone finds the data useful when buying some Soviet Ge's!

[jrod]

Don't really want to necropost but I guess it's better than starting a new topic in this case.
I bought some Russian Germaniums from ebay seller elena8913. Reasonable prices, lots to choose. Below is a link to spreadsheet I made with the transistor measurements. Transistors are MP20B, MP42B an GT402V.
https://docs.google.com/spreadsheet/pub?hl=en&hl=en&key=0AmQTWdBVWu_DdGhTWHpQbXRKSGRGdXJQZVNQMGVQckE&output=html
MP20B are the most usable of the lot I guess and MP42B are bit dissapointing. Datasheet rated at 45-100 they all occupy the lower end of the scale. Guess I will try the leakiest one today in Q1 for Harmonic Percolator and see how it goes. GT402V behave just like the datasheet suggest, although I was expecting more hFE after chromesphere comments and video on youtube. Seems like it's GT402B or GT402E that are higher gain versions. Can't really find either of them on ebay though. The only place that seems to stock B version is this Chinese site http://www.module-igbt.com/electronic-components/transistor/gt402b-ex-ussr-germanium-pnp-transistor-qty-40/prod_38590.html Price seems reasonable so might give it a go sometime later. Also not Russian but close, I should have some Polish germanium transistors in my hands when I go back home for Christmas. They all look quite promising, with gains of 30-140.
Hope anyone finds the data useful when buying some Soviet Ge's!

Great info! Thanks for posting!

[tjdracz]

Mind you they were all tested yesterday evening with the heating on and the room temperature around 20 degrees. Now it's about 16 egrees in my room (cold!) and leakages are definitely smaller, more in line with the low-leakage reputation of russians

[Thecomedian]

Don't really want to necropost but I guess it's better than starting a new topic in this case.
I bought some Russian Germaniums from ebay seller elena8913. Reasonable prices, lots to choose. Below is a link to spreadsheet I made with the transistor measurements. Transistors are MP20B, MP42B an GT402V.
https://docs.google.com/spreadsheet/pub?hl=en&hl=en&key=0AmQTWdBVWu_DdGhTWHpQbXRKSGRGdXJQZVNQMGVQckE&output=html
MP20B are the most usable of the lot I guess and MP42B are bit dissapointing. Datasheet rated at 45-100 they all occupy the lower end of the scale. Guess I will try the leakiest one today in Q1 for Harmonic Percolator and see how it goes. GT402V behave just like the datasheet suggest, although I was expecting more hFE after chromesphere comments and video on youtube. Seems like it's GT402B or GT402E that are higher gain versions. Can't really find either of them on ebay though. The only place that seems to stock B version is this Chinese site http://www.module-igbt.com/electronic-components/transistor/gt402b-ex-ussr-germanium-pnp-transistor-qty-40/prod_38590.html Price seems reasonable so might give it a go sometime later. Also not Russian but close, I should have some Polish germanium transistors in my hands when I go back home for Christmas. They all look quite promising, with gains of 30-140.
Hope anyone finds the data useful when buying some Soviet Ge's!

honestly, I prefer necroposting, it's a lot more sensible than making topic after topic on the same issue, to me at least. A lot of rehashed and reposted stuff gets the reply "do a search function", it seems like that advice would go hand in hand with "bump an original thread instead of making a new one on the exact same topic".

It's a bit surprising to hear the leakage is so high and the gains are so low. They usually measure for me around 20-40uA. As far as gains go, mp20b is a 25mA bias and mp42b is a 10mA bias. That's a lot of current.

[tjdracz]

Honestly, I prefer necroposting, it's a lot more sensible than making topic after topic on the same issue, to me at least. A lot of rehashed and reposted stuff gets the reply "do a search function", it seems like that advice would go hand in hand with "bump an original thread instead of making a new one on the exact same topic".

It's a bit surprising to hear the leakage is so high and the gains are so low. They usually measure for me around 20-40uA. As far as gains go, mp20b is a 25mA bias and mp42b is a 10mA bias. That's a lot of current.

Thought so! Checked some of them again today and leakages are much lower, gains still low too. I guess they must have been bumped up by the radiator in the room and heat from the laptop. Can't see any other explanation.
Also what is meant here by transistor being xy mA bias? I'm clueless with theory here and I'm keen to learn and try to understand our properly so any explanation would be great!