5D3 build.

[sdorer]

I have made a couple of 5E3 amps and then I tried a 5D3 amp because the circuit looked simple and I was curious. Like a dumb guy I find out that the phase inverter is called "biphasic" and that it limits the highs. However the amp sounds just plain bitchin and I wonder why these circuits aren't more popular. I'm glad I didn't read up on the limits of the circuit as I probably wouldn't have built it. The amp is way loud, break up nice, and has a nice wide spread when played softly. Also, I noticed in my amp book that the 5C3 and 5d3 aer identical schematics. I wonder why the folks at Fender called them a different model. Any thoughts?

[Gee]

The 5C3 has feedback whereas the 5D3 doesn't. Also they have slightly different types of paraphase inverters. From memory the 5D3 had better balance (or worse maybe).

[gldtp99]

I built a 5D5 based 30 watter with 6L6GC x 2 cathode biased--- except with cascaded gain stages ---- two 12ax7's (tube halves running in parallel and cascaded V1 into V2) feeding the Paraphase PI---i also added a mostly useless Type 1 PPIMV--- it does limit the vol just fine but it robs the thickness of the tone like a thief.
hot blooded amp !! i'll probably mess with paraphase PI amps more in future builds.........................gldtp99

PS--- 5D5 circuit does have NFB

[sdorer]

My bad. The 2 models with the identical schematics were the 5d3 and 5d4.