AMZ Superbuffer questions

[WickedBlade]

Hello all,

I'd like to implement a variation on the AMZ Superbuffer.
Basically what I want is this:

• use only one opamp (not even 2 opamps in a dual package)
• have 2 buffers on the same board (one will be placed at the beginning of the effects chain, and the other at the end, both commutable independently)

I'll be using a dual opamp with each half going to its own buffer circuit. The questions that arise then are:

• Is it stupid to try and make do with only one dual opamp and should I use 2 single opamps instead? I'm considering noise issues here mainly, and oscillations maybe.
• If I use this dual opamp then, do I have to build 2 vref voltages or will sharing one suffice?
• Considering that I will use only one opamp per buffer, do I still need R1 in the schematics (or R2/R3/R4 if you will)? My understanding was that it was there to make all opamps outputs work together... So what's the benefit with only on opamp?

Thank you for your help!

[Morocotopo]

Wicked, you might want to see the IC Buffer at ggg (General Guitar Gadgets) and buiild two of those in the same box, the difference of the AMZ super buffer is that it stacks four opamps to get better drive. It´s highly unlikely you will get oscillations or extra noise by using a single package, dual op amp.  Of course, you have to be careful with wiring, layout, etc. You can use a single Vref for all the op amps.

[WickedBlade]

Thanks for the tip. I've had a look at he GGG schematics and it's basically a lighter version of the buffer, with R6, C4, R1-4, C2, and R7 'missing'. I guess it answers my question about R1-4 at least.
I think I'm going to build the more complicated version, where I can get back to the GGG design by replacing stuff with jumpers and open links.
It looks like the AMZ superbuffer isn't only about stacking opamps, there are additional caps (probably for noise cleaning) and resistors (R7 to ensure an output impedance I guess, but I don't know about R6 and R4). Maybe Jack can shed some light?

Are you sure I can 'share' vref? I recall I've read some reserves about that but I can't quite remember where... Anyone can confirm or infirm this?

Cheers.

[jkokura]

*Edit* I realized what I posted wasn't entirely what you were looking for.

What I would do is just build two single opamp buffers. Rather than try and utilize one opamp for buffering twice, just build two of these:

http://www.buildyourownclone.com/board/viewtopic.php?f=41&t=18652

Jacob