Opamp suggestions for buffers?

[knealebrown]

Im going to build a buffer from danos schematic on the beavis audio site (link below)

i was wondering if anyone could recommend any substitute opamps that would be interchangeable/you have found too work well for guitar in this type of circuit? Just going to put a 8 way socket in and try them out

http://www.beavisaudio.com/techpages/Buffers/


Thanks Kneale

[head_spaz]

It's not very critical in a stompbox application.
They make so many different opamps because there are many things to consider in trying to accomodate different applications. Things like idle currents, max voltage, minimum voltage, dc offset, bandwidth, input and output impedences etc. Stompboxes are pretty forgiving with regards to those specs.

I tend to prefer the NE5532 for output buffers, since they're cheap, low noise, widely available, well proven, and they have a fairly low output impedence capable of driving down to 600 ohms. But keep in mind that the NE5532 doesn't have a low input impedence.
If you're needing an input buffer, use a TL072, or similar, because it has a high input impedance and won't load down the source that's driving it.
If you're looking for a one-size-fits-all, the TL072's is difficult to beat.
If you wanna compare them with some of the higher spec's chips, try an OPA2132 and see if you can tell the difference. YMMV.

[knealebrown]

thanks man, i will be trying some varying price ranges and also comparing against some Jfet buffers too as its for a university dissertation project (building a true bypass strip with switchable buffers and relay switching) will have to take measurements/ frequency sweeps etc so its important to get varying qualitys of Opamps in there

thanks again

[jkokura]

Essentially, you could use any single opamp and have it work. But whether it sounds good is the question. I think that's why the TL071 is the recommended opamp is because it is reliably transparent, and like the above poster, gives you enough headroom.

You could also build a single opamp buffer using one half of a double opamp like the 4559, TL072, OPA, and another dozen good options.

Jacob