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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Maybe he, or another ilumanted member of this forum can bring some other substitutes! 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. February 18, Transistor substitution in GAR I also want to know if there is a good modern replacement for the 2sb out there. You can buy small quantities on the web I still have some back in my lab.
There are some newer substitutes that aren’t as low R’bb but are acceptable in general microphone preamps. The 85 looks identical except for higher breakdown voltage than 84 so no problem with either. Hi Have these transistors in bad Delta channel.
Other observations about the schematic, the diode across the 2sn737 looks a little odd. Rossi Member Germany Posts: You probably have two of those per mic input. So I’d drop them in and see how it works.
It will work but you’ll have more noise.
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 Hi all, looks like two of the channels of my mixing console were fried when a phantom power coupling capacitor blew up.
2b737 by maxime The Lab. The -E parts are higher beta than the -D. That design looks like around 1 mA nominal set by ohm and Vbe of 2sc The 2SA from Toshiba is an excellent super low Rbb transistor, but it has become scarce.
The original 2sb and 2sD were designed for moving coil head amps with ohm nominal source impedance, so arguably better than needed for ohm source impedance microphones.
The 2SA Hitachi that I pointed out earlier is a popular replacement used in quite a few preamp stages that previously had the 2SB Xatasheet 16, June 06, Rossi probably knows more than I do about what folks are using these days. Looking forward to some results!
Low noise devices are generally graded for beta, as in the more beta the better for low noise applications. March 29, If you sub a newer part, you may want to back off on the current density for optimal noise performance or not.
Started by abby normal The Lab. Bookkeeper Member Czech Republic Posts: 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. Very nice that Mr.
A am wondering what Midas is using or their XL42 preamp now. No simple fix to avoid the scratchy noise with gain changes due darasheet small DC offsets, but you might want to experiment with datashdet quality there.
Started by jrmintz The Lab. I was already off the reservation when Peavey made their lifetime buy on that. Perhaps they are protecting against some latch up condition. The number sounds familiar But I wouldn’t change it here for two reasons. I have not searched the other parts mentioned in this thread, but also dxtasheet web search i didnt found a “recommended” replacement.
They were using truck loads of the 2sd NPN version. 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. You tell me whar a man gits his corn pone, en I’ll tell you what his 2wb737 is. First increasing current there, will decrease input signal swing before saturation, datashete you change other values, but more importantly, I suspect the newer replacement devices are higher Rbb and happier at lower current density.
Roberts joins the thread! April 01, 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. But look at the data sheets for NF vs impedance curves, for something that doesn’t suck into ohms.