Just built a Timmy

[Strat68]

I had to substitute for the 4559 op amp.  My first choice was a 072 which was pretty amazing.  Crazy loud, great tone that's not mushy if you push the Gain and Treble.  The Les Paul needs to be turned up to only about 2 to get excellent sound.  Push it to 10 and you get a very saturated distortion to the point of fuzz.

(tested on a Carvin V3 twin, with the overdrive channel drive at about 4)

I then tried a 4558 which lowered the volume by an order of magnitude.  There was still some great tone but far less distortion at all volume levels regardless of where the Gain and Level were set.  Same for using the guitars volume control.

I'll stick with the 072 for now but I have some 1458's coming to try.  Some folks in various places seem to like them.

For general info, I found a manufactured PCB for it and there are places that sell them if you know how to read a schematic and decode the cryptic descriptions.  But in the interest of the general community's sensibilities on this I'll leave the sources anonymous.  I only bring this up since manufactured Timmy PCBs seem to be taboo (and I understand why) but they are out there.

[roseblood11]

I really liked the TLC2272 and OP275 in this circuit.

[Mark Hammer]

A buddy brought his over to my place and we tried out about a half dozen different chips, including a TL072, NE5532, OP275, CA3240, 4558, and eventually a 1458.  It came as a complete surprise to me, but we both liked the 1458 best.  It did a nice job of taming the harshness.

Sometimes a chip's shortcomings are its very strengths in some contexts.

[Strat68]

A buddy brought his over to my place and we tried out about a half dozen different chips, including a TL072, NE5532, OP275, CA3240, 4558, and eventually a 1458.  It came as a complete surprise to me, but we both liked the 1458 best.  It did a nice job of taming the harshness.

Sometimes a chip's shortcomings are its very strengths in some contexts.

I agree that the 072 can be harsh.  You really have to cut back the treble some and although not too significant, the clipping selection can dial back on the intensity as well. 

It's been really interesting to see what various mods do to pedals.  I haven't done a lot of this since the late 1970's when the only real source was Craig Anderton who was very helpful.   I've done the DS-1 "Evil" mod which really makes the pedal much better.