OPA2604 and OPA2134 as replacement for the usual opamps?

[MetalGuy]

Hi,

I found this french website with optimizations for some well known guitar effects/amps. This is not the first time I see claims that OPA2604 and OPA2134 change the tone alot anf for good. Check out the harmonic spectrum comparison between different opamps. Also I'll be glad to hear from those that  have any experience with these and whether the  $4.28 and $2.63 per opamp respectively /Digikey/ are justified.

http://optimisetonampli.chez-alice.fr/exemple.htm#guv

[WGTP]

As the graphs suggest, IMHO there is a slight difference in tone/gain/impedance/frequency response, etc. between different op amps, not as much as changing diodes (in distortions at least).  Some of the differences can be simulated by changing caps/resistors, etc.  Check out Texas Instruments free samples.