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Argus25 · 12th Sep 2017, 1:10 pm

Hello Thomas,

I can let you in on a secret about germanium transistors and their applications in musical instruments such as guitars and FX pedals etc.

Most American instrument makers of guitars and pedals, if they were not scrimping on the dollar, selected the one and only one best suited transistor at the time, in the early to mid 1960's, made by RCA, which was a low noise germanium type, this was the 2N2613. That is if they didn't subs in a poorer/cheaper older part like a 2N408 or combine it with a 2N2613 as the second stage where the noise wasn't as critical.

Oddly in the USA there were few other types that were specifically low noise. In the UK there was the approximate equivalent of the 2N2613, the AC107. These transistors were initially designed and conceptualized for the input stage of Tape deck amplifiers.

Gretsch in the USA started to put them (2N2613's) in as treble boost amps in guitars like the Rally and the Jetfirebird model in the mid '60's. Gretsch lost the original documentation on these so I reverse engineered them, the analysis and history is here:

http://worldphaco.com/uploads/Gretschdoc.pdf

In the UK slightly less satisfactory transistors were selected for the treble boost application & fuzz, these were transistor radio transistors, like the OC44, OC45, OC71, OC72 etc, because these were less expensive than the AC107, at the time.

What has been neglected though is this:

The Japanese, in the early '60's era, were not confined to one low noise germanium transistor type. Because they basically pioneered battery operated portable tape recorders they made a number of types, there are at least 5. Their classics, equally as good (if not better) than the UK's AC107, or the USA's 2N2613 for this music application, these are the remarkable 2SB439 and 2SB440, both were made by Toshiba. I will let you discover the others, it makes for an interesting journey.

12th Sep 2017, 1:10 pm	#13
Argus25 No Longer a Member Join Date: Oct 2016 Location: Maroochydore, Queensland, Australia. Posts: 2,679	Re: Transistors wanted Hello Thomas, I can let you in on a secret about germanium transistors and their applications in musical instruments such as guitars and FX pedals etc. Most American instrument makers of guitars and pedals, if they were not scrimping on the dollar, selected the one and only one best suited transistor at the time, in the early to mid 1960's, made by RCA, which was a low noise germanium type, this was the 2N2613. That is if they didn't subs in a poorer/cheaper older part like a 2N408 or combine it with a 2N2613 as the second stage where the noise wasn't as critical. Oddly in the USA there were few other types that were specifically low noise. In the UK there was the approximate equivalent of the 2N2613, the AC107. These transistors were initially designed and conceptualized for the input stage of Tape deck amplifiers. Gretsch in the USA started to put them (2N2613's) in as treble boost amps in guitars like the Rally and the Jetfirebird model in the mid '60's. Gretsch lost the original documentation on these so I reverse engineered them, the analysis and history is here: http://worldphaco.com/uploads/Gretschdoc.pdf In the UK slightly less satisfactory transistors were selected for the treble boost application & fuzz, these were transistor radio transistors, like the OC44, OC45, OC71, OC72 etc, because these were less expensive than the AC107, at the time. What has been neglected though is this: The Japanese, in the early '60's era, were not confined to one low noise germanium transistor type. Because they basically pioneered battery operated portable tape recorders they made a number of types, there are at least 5. Their classics, equally as good (if not better) than the UK's AC107, or the USA's 2N2613 for this music application, these are the remarkable 2SB439 and 2SB440, both were made by Toshiba. I will let you discover the others, it makes for an interesting journey.