I realize that I'm way too late to this party. But after over a decade making pedals with opamps, I'm finally getting interesting in old germanium stuff.
If I wanted to get a decent number of germaniums, say 100, where would you look?
Seems like there are no more reliable AC128 transistors, but perhaps some decent equivalents are still out there? Especially since I hear that AC128 was basically a label for leftover germaniums, so the specs are all over the place.
You might be able to get some Russian sources and they tend to have low leakage, but you might be subject to an embargo. The only other place is old transistor radios and cassette players and maybe some old console stereos.
You can still get Russian and Chinese Germaniums at reasonable prices. I bought Chinese Germaniums off Aliexpress. However, you are mainly going to get PNPs. I can also find vintage US made ones at surplus stores. They have a lot of old circuit boards and broken electronics that you can pull transistors from.
The AC128 was used as output transistor in battery operated gear. It is not hard to find an old transistor radio containing a pair of output transistors equivalent to AC128's. Getting 100 of them, well that might be difficult these days.
It's germanium devices day! I just typed in some things to think about for germaniums in another thread:
https://www.diystompboxes.com/smfforum/index.php?topic=133267.0
Germaniums are technological orphans, bypassed by industry long ago. There are remaining pockets of dusty-shelf bins of them in some places. Being late to the party is a problem. Enterprising pedal makers have been buying up bins of leftover germanium devices for over two decades now, and rooting around for more leftover dusty bins. The quality varies with germanium - a lot! - so there's a lot of sorting to be done for good gain numbers and low leakage, as well as low noise. Sadly, germanium sorters often sell of the leftovers after they have sorted out the ones they like.
There are still a few places that make new germanium transistors. I would think of these as placing a bet on getting good ones for pedals, as well as maybe or maybe not having the germanium quirks that make germanium sought out for pedals.
NJ semiconductor. They had some old test equipment for sale on facebook marketplace and i asked the seller if he had any old stock transistors. He said he wasn't in the sales dept but sent me pictures of part of the warehouse. He said to contact sales and they will let you know what they have, may be larger quantities minimum order than you are looking for though.
They are out there, i picked up a few thousand 6 years ago and still have 95% of them.
(https://i.postimg.cc/sMfSsFNz/20190612-222202-2448x1836.jpg) (https://postimg.cc/sMfSsFNz)
(https://i.postimg.cc/5XPztPhC/20190612-222219-2448x1836.jpg) (https://postimg.cc/5XPztPhC)
(https://i.postimg.cc/sBqZYMDf/20190714-180049.jpg) (https://postimg.cc/sBqZYMDf)
(https://i.postimg.cc/WhwrBpSS/20190714-180104.jpg) (https://postimg.cc/WhwrBpSS)
The 2SB56's in the second picture are very similar to AC128 :P
The old Eastern Block countries still have large quantities of Soviet-era Ge transistors. I bought hundreds from Bulgaria, all with hfe around 100 and leakage on a par with silicon. I still don't know exactly how they achieved such low leakage, but Soviet factories look like they continued production and development long after the rest of the world had abandoned them.
The problem now is that sellers are aware of the prices that pedal builders are willing to pay. I bought my stock when they were just happy to get rid of them.
Quote from: Clint Eastwood on May 16, 2025, 02:36:46 AMThe 2SB56's in the second picture are very similar to AC128 :P
I'd say less leakage but not as low as most Russians. The few real AC128 i have are pretty bad but are on par with other transistors from that time period. I did get a bag of each 2SB54 and 2SB56 which were the driver and outputs for most Japan made radios. Also grabbed some 2SB175 but gains are kind of high for basic fuzz. Most Japanese germaniums are pretty consistent in gain and leakage. They also do have gain buckets with a suffix or color code.
Quote from: mozz on May 15, 2025, 08:30:12 PM(https://i.postimg.cc/sMfSsFNz/20190612-222202-2448x1836.jpg) (https://postimg.cc/sMfSsFNz)
Enough seed for big farmland of Germanium trees..!! :icon_wink:
Quote from: mozz on May 15, 2025, 08:30:12 PM95% of them.
(https://i.postimg.cc/5XPztPhC/20190612-222219-2448x1836.jpg) (https://postimg.cc/5XPztPhC)
geeze! there's
some of us have never even had
one Toshiba 2SB56.
Hamfest are one place to look, the bagged ones i asked the seller if he had any transistors, he had them under the table.
What would be some of the one's that is worth getting from ebay, looking to build the typical rangemasters and fuzz faces.looking at MP20,MP21A,1T308V,P416B. whats the current experience with these.
Quote from: Mick Bailey on May 16, 2025, 03:16:08 AMThe old Eastern Block countries still have large quantities of Soviet-era Ge transistors. I bought hundreds from Bulgaria, all with hfe around 100 and leakage on a par with silicon. I still don't know exactly how they achieved such low leakage, but Soviet factories look like they continued production and development long after the rest of the world had abandoned them.
Once you start looking outside of the regulars, there are still stacks of incredibly high quality tubes for next to nothing too. I've also noticed it with diodes/transistors - any of the types regularly used have ridiculous markups, but similar models are still cheap enough.
You can still get a quad of matched, NOS Reflektor 6P14P-EV's for under $100AUD delivered out of post-Soviet states, while getting a single EHX EL84 is over $50 each locally.
I got 10x NOS boxed 6SL7 equivalents and including delivery they were far less than the cost of a single EH tube in the UK.
Thank you all for your advice!!
Quote from: amptramp on May 15, 2025, 04:06:47 PMYou might be able to get some Russian sources and they tend to have low leakage, but you might be subject to an embargo.
Quote from: idsnowdog on May 15, 2025, 06:07:23 PMYou can still get Russian and Chinese Germaniums at reasonable prices. I bought Chinese Germaniums off Aliexpress. However, you are mainly going to get PNPs.
Do you think the Russian sources on eBay are trustworthy? Or are y'all buying from elsewhere?
Quote from: mozz on May 15, 2025, 08:30:12 PMNJ semiconductor. They had some old test equipment for sale on facebook marketplace and i asked the seller if he had any old stock transistors. He said he wasn't in the sales dept but sent me pictures of part of the warehouse. He said to contact sales and they will let you know what they have, may be larger quantities minimum order than you are looking for though.
Woah super cool!! I sent them a message, hopefully I'll hear back.
How much did you pay for those Toshiba 2SB54 and 2SB56? I only seem them for $5/each on eBay.
I think for the bags of 2sb54/56 i might have paid under $100 per about 1200 transistors? I forget the qty. The T59248 raytheons were $10 for 900 pcs.
I occasionally step into deals, such as the 6C10 tubes for $8 each, on a website I ordered 4 just to see if they would ship, and they did. I lost the webpage somehow. The place was in Texas is all i remember.
I've made a number of purchases of Ge transistors from eBay user alexer1 in Ukraine, trading as "SOVCOM (https://www.ebay.co.uk/str/sovcom)". His shop appears to be still active.
Quote from: mozz on May 18, 2025, 02:57:34 PMI think for the bags of 2sb54/56 i might have paid under $100 per about 1200 transistors? I forget the qty. The T59248 raytheons were $10 for 900 pcs.
Woah, I have to be on the lookout haha!! Seems like nothing on eBay comes close to that...
Quote from: bluebunny on May 19, 2025, 03:38:10 AMI've made a number of purchases of Ge transistors from eBay user alexer1 in Ukraine, trading as "SOVCOM (https://www.ebay.co.uk/str/sovcom)". His shop appears to be still active.
Thanks for the tip! Looks like they have decent prices on MP42B, which they say are similar to AC128.
Anyone have experience with the MP42B for a fuzz face?
Quote from: bluebunny on May 19, 2025, 03:38:10 AMI've made a number of purchases of Ge transistors from eBay user alexer1 in Ukraine, trading as "SOVCOM (https://www.ebay.co.uk/str/sovcom)". His shop appears to be still active.
I can vouch for him as well. I have bought tubes and transistors. There's also a guy in Florida that has very reasonable prices.
The Antique Radio Society has these reference guides available for free download. They list European, US, and Japanese equivalents but not Soviet or Chinese because the books were from the cold war.
You can also go to alltransistors.com and do a search based on the part number and there will be a link to compatible replacements. I have found if I change the search terms from si to ge and change PNP to NPN then uncheck the form factor field I can get a list of compatible substitutions if I'm willing to convert the circuit from PNP to NPN.
BP14-2nd-Transistor-Equivalent.pdf
bp85-international-transistor-equivalents-guide.pdf
SAMS-Transistor-Specifications-Manual-4th-1970.pdf
RCA-Transistor-Manual-SC-12-1966.pdf
I bought a big box of transistors last year and I was trying to sell off the excess. I sold a lot of them so I need to update my inventory. They are mostly GE PNPs with HFE between 20-80. Although they are below 100 HFE they work really well in darlington or sziklai pairs. Let me know if you're interested and I will send you my spreadsheet.