Pro Audio Design Forum

I recall using the 723 in my first kit back in the '70s before three terminal regulators became ubiquitous. I'm not sure I see the rationale for using the rail splitter in this design, since a real ground exists at the common point between the two capacitors. If they are trying to deal with one rail...

AFAIK he never got a patent. I vaguely recall some of the pages may have been witnessed (signed by a co-worker). Yes, those are classic engineering notebooks. The pages are numbered for integrity of the chronological order. Gaps with pages left empty are likewise a no-no. I had a classic engineering...

Ok here's that notebook page I found amusing. Sketch of newsreel camera mounted in an old Ford. The actual company this work was done at is ERPI one of the sundry interrelated organizations. FWIW I didn't inherit my dad's neat handwriting or drafting chops, and I even worked as a draftsman long befo...

I have a picture of my dad's ham rig from before he was married... No amateur radio at the house when growing up, but I did my share of SWL. ---- IIRC early DBX VCA were selected discrete (to-92) (edit- that would be to-18) metal can transistors, wedged into a common thermal heatsink to hopefully ke...

I'm kind if busy at the moment but I have some cool stuff I can scan in... engineering sketches of movie cameras mounted into old model A (T?) Fords and such. AFAIK Muzak was not connected to RCA but a letter from the president of WE was addressed to my dad c/o MUZAK. Another data point is we actual...

My dad worked for WE and RCA, among sundry other related companies (Vitaphone, Muzak,,) . He was sent over to England in '30's to record coronation of King George (?). He was a recording engineer for RCA in NYC when he died in 1950's. I have some of his early engineering notebooks which are dated an...

AFAIK the 5534 per it's specification won't drive 300 ohms rail to rail. According to Graeme, the input op amps only swing half rail making the use of 300R resistors possible. These op amps are also running class A in so far as their outputs are always sinking. I asked Graeme some time ago about us...

I don't see much market for a stand alone mic preamp. What about all those studios who need to get a mic or two into their HDD recorder? I used one just the other week to run an AKG condensor mic into a laptop. It is true that if the OM1556 hybrid was used in a traditional mixing desk front end appl...

Yup.. Another point that is mentioned and perhaps worth discussing is the nominal impedance of the feedback network. I've looked at this a little in the context of very low noise front ends for A/D and you can get into current drive issues with standard opamps if you work at very low impedances. AFA...

Thanks, I wish I could use that excuse, but I just skimmed through the pdf linked to and missed that "E" is apparently grounded. I guess "E" stands for earth (?). :oops: I'd have to spend more time looking at an actual implementation to find the claimed advantage of that topology...