Pro Audio Design Forum

Thanks John. I am not sure if it has been mentioned over here but the 2sk389 appears to be obsolete. Which is also why I have a pile of Toshiba 2SK389s. They're still using 12AX7's "over there" aren't they? Unobtanium normally doesn't phase the :ugeek: Linear Systems still make 2SK389s in ...

Upon reflection I believe the "unity CM gain" notation is an observation of how those blocks act together in response to CM signals at the very input, not about how the internal gain blocks respond to local inputs, with only one input per shown. I think you're right about that. EDIT: Note...

National Semiconductor AN-64, "LM381 Low Noise Dual Preamplifier," Joe Byerly and Ernest Long, May 1972.

https://proaudiodesignforum.com/images/ ... _LM381.pdf (pdf, 5MB, searchable)

I'm always getting inquiries from people trying to locate MCI or Otari lamps. The Otari LU2049 axial lead VU meter lamp is a popular request. I think MCM has a suitable replacement for the LU2049 but while looking for a Sylvania "90L" aka 90MB lamp for a Heathkit IG-18 generator I stumbled...

How do I post a pic of this? Use an attachment? Send a link to the file and use the img tag? Send it to me and I'll post it? Thank you for sharing the MEH handbook. I had forgotten about Ian's scan of it. Speaking of Leon Audio, Ian is a member here. He shared what he had on Cohen here with us. htt...

AN104 that you provided may be what ricardo was talking about. Thank you for posting that John. From scanning National's AN104, it looks like it demonstrates how you can calculate noise "piecewise" and then by (power) "summing" the bands deal with all the frequency-dependent thin...

" Photoconductive Cell Application Design Handbook ," Clairex Electronics, 1978. https://www.ka-electronics.com/images/pdf/Photoconductive_Cell_Application_Design_Handbook_Clairex.pdf (Full Handbook, Color, 26.4 MB) This file is huge and takes awhile to render once downloaded. I had to sc...

I just went to the old house today to pickup some stuff and grabbed the National file. Sure enough, right at the front, I had a copy of AN-64 for the LM381 by Byerly and Long of National dated 1972. AN-64 does go into RIAA preamp design but I think what we may be looking for is in the Audio Handbook...

Remember I'm presently a beach bum.

Did not know that. Isn't it winter there?

This doesn't quite explain current noise. That vid didn't explain current noise at all. Still a good background though. Never got the follow-up question. There's an old AD note which was very good on precise calculation of noise including summing several bands when response & source Z isn't fla...