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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Started by jrmintz The Lab.

2SB Datasheet, Equivalent, Cross Reference Search. Transistor Catalog

Started by maxime The Lab. Started by abby normal The Lab. Bookkeeper Member Czech Republic Posts: Hi Have these transistors in bad Delta channel. Is there any equivalent for this?

You tell me whar a man gits his corn pone, en I’ll tell you what his ‘pinions is. Rossi Member Germany Posts: Those are super low Rbb transistors for low Z input stages.

2SB737 Datasheet, Equivalent, Cross Reference Search

Datashee probably have two of those per mic input. 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.

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 Change both transistors in the input stage. April 01, If you sprinkle when you tinkle, please be neat and wipe the seat.

You are about to become the voice of Interplanetary Parliament. Yup, they have been obsolete for years. There are some newer substitutes that aren’t as low R’bb but are acceptable in general microphone preamps. 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.

You can buy small quantities on the web I still have some back in my lab. If you sub a newer part, you may want to back off on the current density for optimal noise performance or not. Just to get the channel 2ssb737 you could probably parallel up a few 2n per, but longer term you want to use a proper low noise part. Thank you very much I also want to know if there is a good modern replacement for the 2sb out there.


I have not searched the other parts mentioned in this thread, but also with web search i didnt found a “recommended” replacement. Also on this forum are some threads about 2sb77 part, but no conclusion what to use instead.

A am wondering what Midas is using or their XL42 preamp now. In the schematic there are 2 2sb Maybe they have REAL much in stock. But that will not last for ever. Very nice that Mr.

Roberts joins the thread! Maybe he, or another ilumanted member of this forum can bring some other substitutes! Looking forward to some results! The 2SA Hitachi that I pointed out earlier is a popular replacement used in quite a few preamp stages that previously had the 2SB I’ve used the npn counterpart 2SC with good results.

The 2SA from Toshiba datashwet an excellent super low Rbb transistor, but it has become scarce. I looked around briefly this afternoon and didn’t see anything obvious Rossi probably knows more than I do about what folks are using 2sb7337 days. The number sounds familiar But look at the data sheets for NF vs impedance curves, for something that doesn’t suck into ohms.

I don’t remember what transistor Peavey switched to. They were using truck loads of the 2sd NPN version. I was already off the reservation when Peavey made their lifetime buy on that.

2SB Datasheet – Transistors, Bipolar, Si PNP Low-Power from ROHM Co.

My stash of s are from my design work back in the ’70s, before I worked at Peavey. Hi all, looks like two of the channels of my mixing console were fried when a phantom power coupling capacitor blew up. As we all know the 2SB has practically become extinct so I thought I’d dataseet Rossi’s recommendation and have them replaced by 2SA actually 2SA which I can get at my local dealer.


Is there anything to consider changing resistor values etc. I typically would have run the 2sb at a little higher current density. That design looks like around 1 mA nominal set by ohm and Vbe of 2sc But I wouldn’t change it here for two reasons. First increasing current there, will decrease input signal swing before saturation, unless you change other values, but more importantly, I suspect the newer replacement devices are higher Rbb and happier at lower current density.

Looking at the noise figure curves wrt source impedance and current density here javascript: So I’d drop them in and see how it works. The 85 looks identical except for higher breakdown voltage than 84 so no problem with either. Low noise devices are generally graded for beta, as in the more beta the better for low noise applications. The -E parts are higher beta than the -D. Other observations about the schematic, the diode across the uF looks a little odd.

Perhaps they are protecting against some latch up condition. 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. One weak link sonically for that design is the uF cap in the gain leg 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.

June 06, Transistor substitution in GAR Transistor substitution question Started by jrmintz The Lab. March 29, February 18, February 26, August 16, ,