Figure 3: rbb’ = 2Ω of 2SB I’ve found the same 2Ω value in Douglas Self’s new book “Small signal audio design”. Although the. 2SB Rohm data sheet. 2SB Silicon PNP transistor Components datasheet pdf data sheet FREE from Datasheet (data sheet) search for integrated circuits (ic). 2SB Low rbb Low Noise Amp Components datasheet pdf data sheet FREE from Datasheet (data sheet) search for integrated circuits (ic).
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June 06, One weak link sonically for that design is the uF cap in the gain leg Is there any equivalent for this? 2ab737 all, looks like two of the channels of my mixing console were fried when a phantom power coupling capacitor blew up.
You dagasheet about to become the voice of Interplanetary Parliament. Bookkeeper Member Czech Republic Posts: Regular transistors will be noisy in this application; I don’t know the NTE part, but I doubt it is a super low Rbb part.
Started by jrmintz The Lab. I also want to know if there is a good modern replacement for the 2sb out there. The 2SA Hitachi that I pointed out earlier is a popular replacement used in quite a few preamp stages that previously had the 2SB That design looks like around 1 mA nominal set by ohm and Vbe of 2sc I looked around briefly this afternoon and didn’t see anything obvious Hi Have these transistors in bad Delta channel.
You probably have two of those per mic input. Transistor substitution in GAR Low noise devices are generally graded for beta, as in the more beta the better for low noise applications. Yup, they have been obsolete for years. Transistor substitution question Started by jrmintz The Lab.
Just to get the channel working you could probably parallel up a few 2n per, but longer term you want to use a proper low noise part. Those are super low Rbb transistors 2db737 low Z input stages. Roberts joins the thread! Other observations about the schematic, the diode across the uF looks a little odd.
2SB Datasheet – Transistors, Bipolar, Si PNP Low-Power from ROHM Co.
Very nice that Mr. Dtaasheet on this forum are some threads about this part, but no conclusion what to use instead. If you sub a newer part, you may want to back off on the current density for optimal noise performance or not.
I’ve used the npn counterpart 2SC with good results. Maybe they have REAL much in stock. But I wouldn’t change it here for two reasons. No simple fix to avoid the scratchy noise with gain changes due to small DC offsets, but you might want to experiment with cap quality there. The 85 looks identical except for higher breakdown voltage than 84 so no problem with either. Is there anything to consider changing resistor values etc.
I don’t remember what transistor Peavey switched to.
I have not searched the other parts mentioned in this thread, but also with web search i didnt found a “recommended” replacement.
It will work but you’ll have more noise.
2SB Datasheet PDF –
The -E parts are higher beta than the -D. Maybe he, or another ilumanted member of this forum can bring some other substitutes!
March 29, Perhaps they are protecting against some latch up condition. August 16, The original Rohm transistors are discontinued; if you can’t source any, try the 2SA or, not quite as low noise but still pretty good, 2N I usually added clamp diodes backwards across the be junction of the low noise devices to make sure they never zener if reversed, as that can make them noisy.
As we all know the 2SB has practically become extinct so I thought I’d follow Rossi’s recommendation and have them replaced by 2SA actually 2SA which I can get at my local dealer. Started by maxime The Lab.
(PDF) 2SB737 Datasheet download
There are some newer substitutes that aren’t as low R’bb but are acceptable in general microphone preamps. Change both transistors in the input stage.
Looking forward to some results! I typically would have run the 2sb at a little higher current density. They were using truck loads of the 2sb377 NPN version.