What Russian Germanium Transistor to Stock up on?

[fuzzymuff]

Just got a a couple of AC125 from eBay a few days ago, one bag of AC125 V and one bag of AC125 V1.  Now, I want to stock up on some Russians, since they are in really good price right now.  What Russian Germaniums to stock up on that that will work well in a fuzz face and tone bender?  What Russian transistors are in the Dunlop Joe Bonamassa fuzz face?

[IvIark]

GT308V for PNP and MP38A for NPN are both great.  They both ranged from 50 to 90 hfe with either zero or extremely low leakage.  For higher gain the GT402B are nice for PNP and ranged from 80 to 190 hfe. I haven't come across any higher gain NPN that are worth buying.  All transistors that I measured were bought in boxes of 50.

[digi2t]

I`ve tried GT404`s for NPN work as well, and I`m quite satisfied with them. Go for the GT404B or GT404G, which are higher gain range (60-250). The «B» and «G» will be in cyrillic letters, whereas the lower gain «A» and «B» (our V sound) look like english letters, so it can get confusing. Here is a cyrillic to english letter equivilant chart. Helps me sort out what`s what with Russian transistors sometimes.

[IvIark]

Yes I got GT404B's as well, but they were very high leakage, with 21 essentially being unusable for anything other than buffers or as diodes.  Out of the other 29 only 3 had less than 0.4mA leakage.  The MP38As were much better with all of them being usable (0.11 to 0.23mA leakage), but I'd love some a bit higher gain.

[digi2t]

Really? Wow, pretty high reject rate. I must have scored a nice lot then, I only had 6 bad ones out of 25.

Essentially, I passed on the MP38`s because of the low gain. Out of any of the other Russian NPN Ge`s that I bought, the 404`s were the only ones I liked. Used it in my Gemini III Dual Fuzz, along with a GT402, and an MP20. There`s a build thread here on the forum, complete with video.

That project really sold me on keeping a stock of the Russian Ge trannys.

[IvIark]

I was unsure of the MP38's for the same reason but I figured that the GT308's sounded great in fuzz circuits despite not reaching the traditional expected "Q2" gain level and I'm similarly happy with the results.  The GT404's I got were from gordelux04 and manufactured in 1982.

[digi2t]

For PNP, I have a bunch of MP20B`s, which for some strange reason, I`ve had a hard time finding more. They range anywhere between 70 and 140. I tried them in a Burns Buzzaround circuit, and they sounded really good. They have a bit of a Muffish edge to them.

I know Jimi built a fuzz with lower gain MP16`s, and it sounded great.

[Thecomedian]

MP25As (20-40hfe) are fine. I have fistfuls of them, and they distort softly or harshly, depending on how you tweak Rc.

[jojokeo]

Hello I'm awaiting some AC125z VI and wondering if they're dark or brighter and higher or lower gain sounding? Also would like to know the same characteristics about the Russian GT2 308 aka SFT308 clone? Thanks guys.

[fuzzymuff]

Nice thanks for your tips.  I just placed another order on a 150 count bag of AC125 VI 75-150 hfe.  So far, I've tested about two dozen AC125 and I've ranged from 49hfe to 144hfe.  The leakage from 67uA all the way 398uA.  I figure the high leakage ones, I would use for tone benders.  I'm still looking at eBay for those russian trannies you all mentioned.  i found that the Russians seem to be in the dark side, not as trebly as the AC125 and others in the tone frequencies....is this a fair statement?

[chromesphere]

Quick comparison of the AC125z vs GT108V:

Edit: i have spoken to orpheus, he has told me he has access to a milatary warehouse of electronics, i dont think the ac125's are going to run out any time soon.  How cool would that be? Like a guitar pedal builders willy wonka factory...

Paul

[effection]

It really depends on the circuit.

I can't speak for other designs, but I have a particular fuzz design in which I'm a big fan of the GT308A.

Really though, Russian germaniums are cheap enough that I'd just do a quick eBay run and make sort of a sample batch to see which ones you like the best and go from there. That's how I learned that I really like the 308A.

[fuzzymuff]

Quick comparison of the AC125z vs GT108V:

Edit: i have spoken to orpheus, he has told me he has access to a milatary warehouse of electronics, i dont think the ac125's are going to run out any time soon.  How cool would that be? Like a guitar pedal builders willy wonka factory...

Paul

Cool!!  That's the seller I got my AC125s from.  Great seller indeed, less than two weeks to the states, thats faster than some some venders I've ordered from    BTW...your youtube channel is informative....thanks mate!!

[fuzzymuff]

It really depends on the circuit.

I can't speak for other designs, but I have a particular fuzz design in which I'm a big fan of the GT308A.

Really though, Russian germaniums are cheap enough that I'd just do a quick eBay run and make sort of a sample batch to see which ones you like the best and go from there. That's how I learned that I really like the 308A.

How are the hfe on those?  I read the specs and it states "25-75" hfe, but are those the actual hfe less the leakage, if not then the hfe maybe much lower.  The price is fantastic, $25 for 100 count, may just pull the trigger on it.

http://www.ebay.com/itm/Germanium-PNP-Transistors-GT308A-USSR-1980s-QTY-100-/160589077755?pt=LH_DefaultDomain_0&hash=item2563dadcfb

[chromesphere]

Cant speak of the GT308a, but i had bad luck with GT308v.  they measure low as the test conditions had a higher collector current then what your likely to test yourself in the usual methods us diy'ers are using (including the DCA55 i believe).  They are also ridiculously sensitive to ESD.  Thats the GT308v though, not sure about the A variety.

Orpheus is good to deal with.  Always helpful.  Do a search on ebay for ac125 and you will see the bags he sells.  If you buy a bag of the (V) variety 50-100 hfe and a (VI) variety 100-150 hfe you will have ALOT of sets on hand.  I have the quoted hfe's to be very accurate!  Some hfes are just way out of the ballpark, but i'd say...rough guess...70% in spec?  70% between 100-150.  Thats pretty dam good from my experience.

The first ac125's i bought off him, i couldnt find any information on the net.  I was worried about the (z) and the (v) (vi).  I took a risk on a bag and they paid off!  fyi the z stands for 'high voltage'  they can take a higher voltage then the non z variety.  Doesnt effect hfe either.  Orpheus has since updated the listings to show what (v) and (vi) actually mean to make it easier for people new to the ac125.

I have done a few sound comparisons between ac128's and 125's and their difference is subtle to my ears.  They arent a 'spectacular' sounding transistor, but i think they are a very good all rounder.

I have a bit of a history with the ac125

Paul

[chromesphere]

As far as russians go the gt402 is a great sounding transistor, i wish i had of bought more though because they are now extinct.  The gt108v and gt309g are my pick of the modern 'ufo' type of russian, with the gt309g sounding very slightly older and noiser to my ears (in a good way), and alas...extinct again!  The GT308v is one to avoid imo for reasons stated.  People have had good luck with them.  I didnt.  There was another russian i bought...gt422 something.  Man they were useless.  The hfe's were low, but the actual frequency response was terrible.  Another one that sounded very good is the mp21D which is super cheap .  The hfe's are not what is quoted.  You'll get 40-70 probably.  But i would sacrifice the slightly low hfe on q1 / q2 for the great sounding frequency response of these little puppies.

Anyway, thats a crash course in what i have learnt so far.  Hope it helps.

Paul

[Thecomedian]

It really depends on the circuit.

I can't speak for other designs, but I have a particular fuzz design in which I'm a big fan of the GT308A.

Really though, Russian germaniums are cheap enough that I'd just do a quick eBay run and make sort of a sample batch to see which ones you like the best and go from there. That's how I learned that I really like the 308A.

How are the hfe on those?  I read the specs and it states "25-75" hfe, but are those the actual hfe less the leakage, if not then the hfe maybe much lower.  The price is fantastic, $25 for 100 count, may just pull the trigger on it.

http://www.ebay.com/itm/Germanium-PNP-Transistors-GT308A-USSR-1980s-QTY-100-/160589077755?pt=LH_DefaultDomain_0&hash=item2563dadcfb

Those Hfes are taken from the Mfg sheet on how they should perform. You can do a "Search Engine" on those doc sheets.

for example: http://alltransistors.com/pdfview.php?doc=gt308a-b-v_1t308a-b-v.pdf&dire=_russia

I've heard the 80's transistors of Ge aren't so good. Doping material or construction practice changed, changing their "sound. THis might be where "darker" or "trebly" comes from for the others.

[chromesphere]

One final 'tip' for anyone playing along at home.  

Its really easy to buy ANY germanium thinking your getting a bargain when your not.  30 transistors for $7!  Bargain!  Wait...add the delivery.  Another $6.  So its $13 divided by 30 = 43c.  Thats 'ok' in my books.  But the method i just showed you is something i ALWAYS do before i hit the buy it now button.  Its a good idea to see the unit cost before you decide. A 'good price' depends vastly on the transistor you are buying and how badly you want them i guess.  Likewise theres no point paying 25c a transistor if they arent going to measure / sound very good.  And conversely dont pay $1+ a transistor for run of the mill russians, when you can get another model cheaper.

Thats why i think the ac125's are currently the pick of the bunch.  You have to order ALOT (1 x (v) and 1 x (vi) = 300 units).  But you get then for around 30-35c each, they measure well and they sound good.

Confused?  Me too.

Ok, i'm done 'rambling'

Paul

[Thecomedian]

I still have packages of transistors from 80's Archer.

Jfets are 99c a piece, 15 2n3904's are 2$ a pack.

http://www.radioshack.com/product/index.jsp?productId=2062608
http://www.radioshack.com/product/index.jsp?productId=2062609

1.49 for a SINGLE 2n3904, and that isn't factoring in the shipping cost.

I think any transistors below 50c is a steal, especially if it is made of Ge.

http://www.radioshack.com/product/index.jsp?productId=12668957&numProdsPerPage=60

8 dollars for a single Ge transistor these day.

The shipping could be an outrageous 20$, and those 30-50 bulk Ge transistors are still a huge deal compared to the major retailers. As long as you're buying ones which have very little negative feedback about them, or have a high reliability/aging rate, it should e fine. Tin whiskers can grow in the cans, shorting them and causing them to fail. Those whiskers can be removed through some methods to be found online, without destroying the Tx, if youre careful.

[chromesphere]

Lucky we arent paying 80's prices then i guess. Looking at the current market, i would agree that any (decent) ge's under 50c is a steal.

Edit: some people may like to pay more, some less, but i think that what im comfortable paying compared to the next person isnt really relevant.  Keeping track of what your paying on a per unit cost is something i have personally found useful.

Paul