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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I typically would have run the 2sb at a little higher current density.
2SB737 Datasheet, Equivalent, Cross Reference Search
If you sub a newer part, you may want to back off on the current density for optimal noise performance or not. The number sounds familiar Looking forward to some results!
But I wouldn’t change it here for two reasons. Maybe they have REAL much in stock. Those are super low Rbb transistors for low Z input stages. Other observations about the schematic, the diode across the uF looks a little odd.
Regular transistors will be noisy in this application; I don’t know the NTE part, but I doubt it is a super low 2sb7337 part. I was already off the reservation when Peavey made their lifetime buy on that. Very nice that Mr. 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.
Is there any equivalent for this? Yup, they have been obsolete for years.
Also on this forum are some threads about this part, but no conclusion what to use instead. I have not searched the other parts mentioned in this thread, but also with web search i didnt found a “recommended” replacement. Transistor substitution in GAR The 2SA from Toshiba is an excellent super low Rbb transistor, but it has become scarce. February 26, Rossi probably knows more than I do about what folks are using these days. March 29, 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.
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 ‘pinions is.
2SB737 Datasheet
Perhaps they are protecting against some latch up condition. Bookkeeper Member Czech Republic Posts: Hi Have these transistors in bad Delta channel. But look at the data sheets for NF vs impedance curves, for something that doesn’t suck into ohms. A am wondering what Midas is using or their XL42 preamp now.
Low noise devices are generally graded for beta, as in the more beta the better for low noise applications. There are some newer substitutes that aren’t as datashert R’bb 2sb73 are acceptable in general microphone preamps. Started by abby normal The Lab. You can buy small quantities on the web I still have some back in my lab. April 01, No simple fix to avoid the datashert noise with gain changes due to small DC offsets, but you might want to experiment with cap quality there.
2SB Datasheet PDF –
The -E parts are higher beta than the -D. Looking at the noise figure curves wrt source impedance and current density here javascript: Started datashfet jrmintz The Lab. 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. Is there anything to consider changing resistor values etc. I don’t remember what transistor Peavey switched to. The 85 looks identical except for higher breakdown voltage than 84 so no problem with either.
But that will not last for ever.
August 16, If you sprinkle when you tinkle, please be neat and wipe the seat. That design looks like around 1 mA nominal set by ohm and Vbe of 2sc Thank you very much My stash of s are from my design work back in the ’70s, before I worked at Peavey. One weak link sonically for that design is the uF cap in the datasyeet leg They were using truck loads of the 2sd NPN version. So Datashdet drop them in and see how it works.
Just to get the channel working you could probably parallel up a few 2n per, but dataxheet term you want to use a proper low noise part. Roberts joins the thread! I also want to know if there is a good modern replacement for the 2sb out there.
Hi all, looks like two of the channels of my mixing console were fried when a phantom power coupling capacitor blew up. You are about to become the voice of Interplanetary Parliament.