OC71 Tranny question...
What is the sonic difference between the OC75's and OC71's? Are the OC71's fewer and far between?

From what I understand the OC71's are a little lower gain than the OC75's, but The Captain would be the best person to answer this.

I believe the OC71 is higher gain than the OC75.

Re: OC71 Tranny question...
Taken from MrPicard registry: -214, 17/10/2007, Dave Main, Grey Hammerite, OC71 / OC71 / OC71, No LED, Internal trimmer; Low Gain; Marked 2 of 2 It's a low gain version MKII, so far two have been made.

Seeing the whole OC75 / OC71 issue bubbling around the last few months (or is that years) I thought this might help: I have a regular mkII with a trio of OC75's (no 194 26/4/07) and a custom mkII with an extra selector switch on the side similar to that on the 1966 - but in this case switching between the regular mkII voicing and that of a Marshall Supa Fuzz - which uses a trio of OC71's (no 230 7/10/07) It is a little strange because the Marshall fuzzes used triple OC75's (I have two of them) and despite supposedly having their maximum gain/saturation limited (a fact which I believe applied to the earliest rather than later Marshall versions) are very gainy with masses of darkly distorted delight on tap - I had expected my custom mk2 to be slightly compromised on output because of the 71's but have to say that it does stack up very nicely against my originals - maybe a bit brighter but on a par in other respects. Comparing the regular OC75 mk2 against the mk2 option of the custom OC71 pedal, frankly there is not that much difference at all - maybe the 75's give a more extreme ride / less control over feeding back at stage levels but............read on Using a nice 65 Fender Duosonic into a NOS valved Matamp Minimat with all controls at 13.30 (on the clock face) into my current favourite small cabinet - a closed 2x12 custom Park cab loaded with a T731 G12 15 watt alnico (july '64) and a T1217 G12H 30watt ceramic (february '66) with the attack on both pedals maxed out to achieve similar output levels I had the regular mk2 at 12.00 and the custom at 13.30 so the 75's are kicking out a little more overall volume - tonewise the OC75's are (at that setting) a bit more aggressive - maybe brighter would be the better word. To achieve similar outputs between the pedals I had the OC75 (regular mk2) with its level at 12.00 but needed to set the custom version at 13.30 - that level of difference in overall volume held up when maxed too. Noodling around for half an hour to get a good feel for them both and keeping to the amp setting - already distorting but not madly so - can make the following statement. Hitting single notes the regular OC75 model sustained for getting on for ten seconds until gone - with a nice smooth decay - a few seconds more and then the amp started to pick the harmonics back up again and start into feeding back. The custom with its OC71's held the note (at the same setting levels) for a couple of seconds less and had less of a tendency to feedback - similarly with open chords there was a slight difference with the degree of sustain and length of decay (although the decay was just as smooth/sweet) - Of course by goosing the volume on the amp or the level on the pedal it was easy to get the custom mk2 exactly matching the OC75 version but it did need more overall volume to get the amp feeding back the same. For my style of playing which is rooted in sixties and seventies blues I tend to avoid running my amps too hard preferring that bit more flexibility or control. For example I have the boost on the minimat set with a non-latching footswitch - rather than the one that came with it - and generally run with ten percent or so in reserve - using it that way it was a doddle to get either of the two pedals singing back to me through the speakers. THe other option of course is to run everything maxed and use the guitar controls to keep a cap on things until you need them - I always find this sucks a bit of tone from what I am looking for so prefer to set things up to the point where I can get what I need by digging into the strings that bit more heavily. I would say that at reasonable amp levels there is very little between the two transistor types that you cannot compensate for with your setup - to call OC71's "low gain" is daft but with my two pedals at least it is true that with everything else pushed to the limit the OC75's are the more aggressive setup - but at the cost of control - so if you want your sound right on edge of losing it to the feedback then the regular 75's are the ones - (I would imagine that an OC81D equipped version would be even more hairy) - but if you want that bit more flexibility without compromising on where you can get to if needed then the 71's are just peachy - of course you can get exactly the same with the 75's just by backing off slightly on pretty much any of the controls - I am not talking of any major differences here - it is a lot more subtle than that but on an exact like for like I think what I am saying will hold up. Another consideration is that David has set each pedal up slightly differently and I am certain that if he chose to he could get either of these transistor choices performing more or less identically! I didn't get into the Marshall option in any of this - basically that just gives a darker sound which leads you to believe the note is saturating differently - but that is another story! I hope that this helps rather than confuses people - G

Thanks for the info.

Interesting read Graham! I have a Supa Fuzz that was "restored" by Proanalog. Has a trio of Mullard OC71 transistors. I also have a D*A*M with OC81D transistors. The Supa is darker, more compressed and has a more aggressive voice with more spit around the edges and on the decay. Less midrange as well, though not "scooped". Years back before D*A*M, I was desperately looking for a good MKII clone and Proanalog was the favorite at the time. I was told that the OC71s packed the most gain and compression with the OC81D and OC75 coming 2nd. Don't know how faithfull the rest of Scotty's "restoration" of my Supa was, but it also packs more output than my D*A*M. About a 1/3 more output. The signal gets too compressed with the output knob full out. Unity is around noon and that's usually where I set it.