BUF634P alternatives in XP-7?

[Rhydon]

I currently own a Ray Sammuels XP-7 and was wondering if its BUF634p's are rollable. Has anyone tried using different buffers for the XP-7?

 

[bg4533]

There isn't anything pin compatible with the BUF634P. You can make an adaptor to try other buffers. The Intersil HA3-5002 is the PPA V1 buffer and many prefer it over the BUF634P. You might be able to get discrete diamond buffers working, but YMMV.

 

[amb]

The BUF634P (DIP8 version) pin-out happens to be the same as a standard single opamp, except that there is no inverting input, and pin 1 (either NC or used for some other purpose on a opamp) is for bandwidth/quiescent current control. If you add a small jumper wire between pin 6 and pin 2 at the BUF634P socket under the board, then you could roll a high-current opamp in its place. The opamp will then operate as a closed loop voltage follower buffer with unity gain. With this mod, you can still roll back to the BUF634P without the need to remove the wire jumper because the BUF634P doesn't use pin 2.

You could try the Analog Devices AD811AN or the TI/Burr-Brown OPA551PA opamps. Both of these are high output current (100mA and 200mA respectively), and do not have internal connections to pin 1, so it's safe to use in place of the BUF634P regardless of whether there is an existing bandwidth control resistor at pin 1.

Whether these sound better than the BUF634 is open to question, though.