Oh God here we go again....jrb32 wrote:I’m pretty sure you could modify the preamp of a III to a IIC+ without much problem and get 95% close to a IIC+ easily enough. They’re not some mythical creature that have a hidden mystery component inside and some are definitely better (and worse!) than others in that they vary a lot in resistor and cap type. They also vary a lot in values and different components if they were an original factory C+ or an upgraded C. It will take some minor PCB mods on a III to do this, at the least disconnecting some components and maybe running wires to other bits of the board but it's definitely possible! I’m planning on doing this though to my recently aquired III Early Black Stripe and will report back. I would imagine the reason the III+ mod doesn’t replicate this turning the III into a clone of the IIC+ preamp because the III+ mod is more simple component value changes or cap additions rather than any PCB mods which would be time consuming and costly for Mesa.
For as close a conversion as possible, the more difficult bit to sort is the output transformer and the power voltage rails which are different on the III vs IIC+. If you have an early Black Stripe III with the IIC+ transformer I don’t see this as impossible though. You’d need to add a filter cap and mod the PCB slightly for the different voltage rails but it’s certainly achievable.
It wouldn’t be a ‘verified’ IIC+ but would be near enough identical. I’ll try it out and see what happens give me a few weeks though with work commitments at the moment though.
Jon your intentions might be noble but seriously if it was as simple (or "minor") as you describe it'd have already been done.