The construction booklet for the phono preamps says: "Q1, Q2, Q3 Q101, Q102, Q103 are 2SB737 transistors. These are supplied in the kit. To the best of our knowledge, The Signal Transfer Company is now the only source of these transistors in small quantities."
Are these supplied with the PCBs? If not, any suggestions on where to get them?
Are these supplied with the PCBs? If not, any suggestions on where to get them?
Signal Transfer Company used to sell those 2SB737 transistors, individually, before the global pqandemic. Since then I believe S.T.C. are only selling bare PCBs.
2SB737 transistors are obsolete and out of production. There are many counterfeit "duplicates" on eBay and elsewhere, with terrible performance.
Your best option, your only option, is to choose a replacement transistor from among those you can buy today, which are known with 100.00% certainty to be genuine and not counterfeit. That means buying from a trusted source such as DigiKey, Farnell, Mouser, Element14, etc. The replacement transistor that you choose won't be quite as good as the 2SB737 but it will play music.
You Choose.
2SB737 transistors are obsolete and out of production. There are many counterfeit "duplicates" on eBay and elsewhere, with terrible performance.
Your best option, your only option, is to choose a replacement transistor from among those you can buy today, which are known with 100.00% certainty to be genuine and not counterfeit. That means buying from a trusted source such as DigiKey, Farnell, Mouser, Element14, etc. The replacement transistor that you choose won't be quite as good as the 2SB737 but it will play music.
You Choose.
The 2SB737 is indeed a problem
Signal Transfer has a stock of them, but they are in Gareth's hands at present. I don't know how many he has. I don' know if or when I'll be able to get hold of them.
Last time I needed a low-rb transistor I used the 2SA1312 in SMT, two in parallel in each position. Not sure if there's a leaded version readily available.
The definitive work on low-noise BJT selection is the chapter in The Art of Electronics by Horovitz & Hill; must be the Third edition. It is very good indeed with lots of real measurements.
Hope that's some help.
Signal Transfer has a stock of them, but they are in Gareth's hands at present. I don't know how many he has. I don' know if or when I'll be able to get hold of them.
Last time I needed a low-rb transistor I used the 2SA1312 in SMT, two in parallel in each position. Not sure if there's a leaded version readily available.
The definitive work on low-noise BJT selection is the chapter in The Art of Electronics by Horovitz & Hill; must be the Third edition. It is very good indeed with lots of real measurements.
Hope that's some help.
Can I suggest you look at the Zetex ZX851 and ZX951 devices as a replacement?
Measured rb' of 1.3-1.4 Ohms (a few folks on the internet have done the measurement legwork and H&H speak highly of them from the noise perspective as well).
(I published a design in audioXpress using these devices in Feb and March of this year with a measured input spot noise of <250 pV/rt Hz on the MC input using a QA401).
Measured rb' of 1.3-1.4 Ohms (a few folks on the internet have done the measurement legwork and H&H speak highly of them from the noise perspective as well).
(I published a design in audioXpress using these devices in Feb and March of this year with a measured input spot noise of <250 pV/rt Hz on the MC input using a QA401).
Do I need to find an an NPN or PNP. How about the ZTX851 as suggested above?
John Roberts looked in his boxes and found some quantity of vintage 2SB737.
2SB737 Transistor
While you read many untrue things on the interwebs, this one I believe. John was in the right times doing the right things (audio kits), and the vendor KA-Electronics is a sophisticated audio designer and fan who would know good from bad.
Can I suggest you look at the Zetex ZX851 and ZX951 devices as a replacement?
Measured rb' of 1.3-1.4 Ohms (a few folks on the internet have done the measurement legwork and H&H speak highly of them from the noise perspective as well).
(I published a design in audioXpress using these devices in Feb and March of this year with a measured input spot noise of <250 pV/rt Hz on the MC input using a QA401).
Where might you source these?