TL081 and TL082 in Mixer

[argonrepublic]

Thes two are in each channel strip of mixing console. Could somebody tell me what is their function and can I install an improved chip. They console was made in 1984. There no other ICs in channel just Caps, resistors, and Pots.
Thanks

[adrome00]

Hi argonrepublic!
Those are operational amplifiers, with standard pinouts. The TL082 contains two seperate op-amps in one chip.
The TL072 is slightly better according to specs than the TL082. It has lower noise. They are cheap, available, and can be changed readily.
But there are certainly many other op-amps you can use such as LM833 for much lower noise. You can try to optimize noise, distortion, or frequency response. They are often trade-offs.

I hope this helps.

(added: I am interested if anyone knows more about the TL082/TL072 story ?? )

[schnullimaus]

Those TL072, TL082 have JFET input stages.
When exchanging against other, better opamps
I would first try to stay with JFET Types, such as
OPA2132, OPA2134, OPA 2604 etc.

The LM833 is a great, cheap opamp,
but it has bipolar input stages, resulting in
higher currents flowing through the input pins.
If your circuit uses very high resistances,
additional errors might be included when
swapping JFET against BJT. I use LM833 a lot
exchanging against those 4560, 4558 etc standard
types.

Regards,
Stephan

[adrome00]

Stephan,

Ah, yes, so it does, and you have a very good point!

[Bill Fitzpatrick]

Originally posted by argonrepublic
can I install an improved chip.

You can install an improved chip but you are unlikely to hear any improvement unless you believe there will be an improvement. It will be a change for the sake of change.

[argonrepublic]

I found a replacement. Mine are National are defective so I have to replace.
Analog devices has AD711 and AD712. Both have a number of variations (suffixes). Any suggestions? I am using dip sockets.

[cpemma]

See the datasheets, some will be smd package. Or just get CN suffix if listed, that's DIP.

At the lower end of the price range, LF351/353 are better than 081/082 and easy to find.

[argonrepublic]

There are about five of them that are DIP. I think different temp ratings and other characteristics

[cpemma]

Unless you've another source, Futurelec carry both those AD in DIP and are cheap shipping, even to the UK.

Oddly, the dual is cheaper than the single...

[calvinhpk]

i'm using JRC 072D aka TL072 opamp currently.
I wanted to upgrade to BB OPA2604 or OPA2134.

i) Would like to know what's the difference btw 2604 and 2134?

ii) What are the things that i need to take care off?

iii) I read many sites that recommend to put a capacitor at the V+ and V- pins (pin 8 & pin 4) with a 10uF capacitor. What is the function of these caps? Why we need this?