It's been a while since I posted, I've just been absorbing so much info from the various sites.  This is quite an addictive hobby.  I've got 2 distortions and a fuzz under my belt now, and I'm working on the phase 45 off of tonepad.  I'm finished with the board, and I socketed the transistors.  I ordered 12 jfets to try to get a couple pair of matching ones (my friend is building one, too).  I tried swapping transistors and doing it by ear, but the differences are subtle and my ears just got tired after a while.  I want to match these the right way.  I read RG Keen's page on JFET matching, but I'm sorry to say my schematic skills aren't quite up to snuff yet.  Is there a layout version of that circuit out there?  If not, what is the IC, and how is it connected? What is Vmid?  Is the 10-47uF cap a range of values?  Is the Vgs "voltage from gate to source" of the tested device? Sorry so many questions.  Thanks for your time.
-David Fisher

I'll give this a go but I might miss something so... :wink:

The IC looks to be an opamp.  Probably any one would work.  741 or something like that.  As for how to hook it up, just look up the data sheet for what ever op amp you're using and there should be a diagram with the schematic symbol for the IC with the pin numbers beside them.

Vmid is probably just another way to say Vref (Voltage refernce).  It's half of the voltage to bias the IC.  So for the 9v that's in this circut Vmid is 4.5v.  You don't really need to know that becouse it looks like the two  10k resistors are already forming a voltage divider, splitting the 9v in half.

As for the voltage from gate to source, I would assume that it's for the Fet but I'm not absolutly sure...

hope this helps, good luck and post how it sounds with the matched trannys if you could.  I'm interested to know... :lol:

I made a pcb for the fet matcher (i know, it's like using a shotgun for killing mosqitoes) if you want it i'll mail it to you.

Gringo, a PCB? Really?  Can you scan it or email a picture of it?  A shotgun may be necessary, depending on the mosquito problem...
dfisherdds@juno.com

Boxed the Phase 45 last night.  Thanks for the FET matcher layout, Gringo.  I tried doing it on copper board with rub-on transfers, but the surface didn't etch well at all.  I'm not sure if my etchant was defective or there was stuff on the board, or what.  (The board looked clean).  Even the blank side didn't etch well at all.  I need to solve this problem so I can make more complex circuits.  Gave up and did the FET matcher on perf, and it worked very well.  Out of 12 JFETS, I got 4 pairs that were close to each other in range +/- .01  Two were an exact match at 1.21.  The closely matched FETS sounded by far the best, but I noticed something else that was interesting.  The higher values sounded better than the lower values: ie. the 1.11 - 1.12 combo sounded better than the .79 - .80 combo.  More presence, or a "brighter" sounding phase as opposed to the "darker" sound of the lower values.  Of course, you have to adjust the trimpot to the "sweet spot" for each combination, but overall, the higher values were better.  I imagine you'd have to have a lot of FETs to choose from if you were doing the phase 90, to get 4 closely matched.
I really like the sound of the phase 45.  I have an old MXR Phase 90.  More swoosh, but pretty obtrusive as well.  I play mostly bass, and the Phase 45 is something I might use occasionally with that (sounds nice with my Ric)  I must have gotten the last RTS boards from Tonepad (Francisco Pena) as they are sold out for the moment.  Cool stamps from El Salvador, FP!  This is a great hobby.  I'm hooked!

I really enjoy reading this kind of message!!!!

Have fun with your pedal!

Fp