diode compression opamp

[sean k]

http://www.diystompboxes.com/analogalchemy/pedals/diodeopamp.html

  Could this single opamp be run from a 9volt supply by adding 4.5V through resistors to the positive input and the base of the 2N5089?
 I mistakenly used this circuit in the insanity box and have just realised that it was working like it was because the legs to a negative supply go to earth without proviso for biasing the gates.

[sean k]

A bit of an update
 I've gone over the board I built which is the insanity FX but I replaced the 4558 with the discrete opamp at the top of the page in the link from the above post.
Whats happening is that the signal at the + input is gating quite badly so only signal over a certain voltage is getting through.So what I did was inject the guitar signal at point around Q1 and Q2 to see is the stages beyond it were working.Signal applied,through a cap,to the base of Q3 was the loudest and proves all the stages were beyond Q3 are working fine.This was the loudest input and was similarely loud either side of the 1N914 at say 12.the next lodest point was at the base of Q2 at 7,compared to the 12,next was at the tied emitters of Q1 and Q2 and the collector of Q2 at 5.So it would seem that Q1 collector bias resistance to ground is the problem which is setting the turnon for the base too high.Am I right in thinking that and that a trimmer to adjust could solve this problem?