oddball DOA's

[mrphotodude]

few interesting DOA's i picked up for nothing... no real info available that i can find on either. Anyone see these before?

 

[emrr]

It was pointed out in some long lost thread that many of these mystery discrete opamps have poor high frequency response and low current drive capability.  I'd stick them in something and measure.  I have a bunch of Union Carbide op amps that roll of pretty fast after 10kHz. 

 

[JohnRoberts]

Back in ye very olde days, operational amplifiers were building blocks used in analog computers for simple adding and subtracting.

Operational amplifiers were noted for (relatively) high open loop gain, (relatively) high input impedance and perhaps (relative) DC accuracy but these old devices will be slow and over compensated so not very useful for audio. The not very modern ua741 generally kicked their ass and that is a nothing opamp by today's standard.

JR

 

[kato]

They're from the pre-IC days of function blocks. I believe most if not all devices in this exact package are op-amps, but since there are dozens of uses for opamps, there's no guarantee they're optimal for pro-audio.

There's at least one GroupDIYer who swears by the ballsy sound of his Analog Devices 40J which are still available from BudgetTronics for 25 euro or probably a dollar at a flea market. No specs, but I'd assume they would technically be outperformed by a 47¢ TL071.

Worth trying at least, right?

I'm kinda fascinated by these things from an antique electronic perspective, so I'll dig up some vintage ads you might enjoy...

 

[emrr]

Yep, my Union Carbide pieces might be the ultimate bass DI.  : )

 

[kato]

Also Ken, I've got a DVD on the way to you in today's mail.


Here's an advert from 1967:

From 1969:

Some specs and prices from the 1974 models: