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.
Balanced Phono Preamp BOM in spreadsheet format
As promised... Hope this helps anyone else putting one of these together.
It's a txt file to allow uploading here. Change extension to .csv and open in Excel, etc.
As promised... Hope this helps anyone else putting one of these together.
It's a txt file to allow uploading here. Change extension to .csv and open in Excel, etc.
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).
🙂
2SB737
In my D.S. tt preamp I got my 2SB737 from utsource. At the time I bought 48 new one (1 year ago) but as I looked up now you still can find only used one. Transistors are long term reliability. Could be interesting in trying them!
In my D.S. tt preamp I got my 2SB737 from utsource. At the time I bought 48 new one (1 year ago) but as I looked up now you still can find only used one. Transistors are long term reliability. Could be interesting in trying them!
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.
I have just given the Signal Transfer website another overhaul and it works more smoothly now.
I would like to thank everyone who has placed orders with me in the last two weeks. All orders were dispatched with 24 hours of receiving the funds.
I would like to thank everyone who has placed orders with me in the last two weeks. All orders were dispatched with 24 hours of receiving the funds.
Hello,
I got mine off RS Components in the UK, and Mouser also has them. As Mark indicates in his link, there will be other sources as well.
I got mine off RS Components in the UK, and Mouser also has them. As Mark indicates in his link, there will be other sources as well.
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I see what happened. The text refers to ZX851, the schematic to ZTX851. There are many sources of the latter 😊.
Hello Everybody.
The Signal Transfer PCBs are selling fast, and I need to arrange for some more to be manufactured.
Can anyone recommend a reliable PCB manufacturer on the British mainland? Nothing more complicated than double-sided is required.
Many thanks in advance.
The Signal Transfer PCBs are selling fast, and I need to arrange for some more to be manufactured.
Can anyone recommend a reliable PCB manufacturer on the British mainland? Nothing more complicated than double-sided is required.
Many thanks in advance.
Terminology clueless Yank here, what's the British mainland? Is that Wales + Scotland + England while excluding Northern Ireland?