This is a copy of the 6G2 Princeton circuit. It took me a while to get this one right. The Chassis is from Mojotone. Unfortunately, the current chassis sold by Mojotone has a power transformer cutout for a low powered 5E3. So, I tried using that transformer set at first...and it did not work. I wound up buying a Mercury set specifically for the 6G2. It was too small for the Mojotone chassis but when I turned the transformer 90 degrees, it had enough space to fit with new screw holes for that orientation.
Secondly, once the amp was completely assembled, it had an oscillation issue. After quite a bit of searching, I found the oscillation was coming from the yellow lead going into the screen of the first half of V2 (12AX7). Once I found it, I redressed the lead closer to the body and the oscillation disappeared. I will probably go back in and put a shielded cable in the place of the push-back wire and run it under the eyelet board.
If you are considering an amp like this, I would suggest going with the correct transformers for this schematic and reorienting the PT and OT. The version that finally worked for me was the original Fender schematic. So, I would follow that. I did run a twisted filament pair for modern grounding and used a grounded power cable. Of course, bypass the death cap. You may see where I modded the rectifier tube with diodes, but I wound up removing those...In fact, I wound up pulling this amp apart a couple of times...hence the parts and eyelet board shown in a box...but the final result was a beautiful sounding 6G2 amp...and it was WELL worth the initial frustrations.
Finally, I mentioned Mojotone a couple of times. I spoke to a representative from Mojotone and he explained that the chassis' were ordered, in bulk, by a customer that wound up not using the order. I think Mojotone is a great company. I order from them quite often. I just want to make other builders aware of the issue with the transformer cut out. Not a big issue if you don't mind altering the chassis, but possibly a big issue for builders who aren't comfortable with making alterations.
2 окт 2024