Princeton Reverb vs Deluxe Reverb

[Randall]

Why does a Deluxe ab763 sound louder and more robust than a Princeton Reverb with a 12" speaker? They look quite alike to me, both having a pair of 6V6's. The Deluxe has the long tailed pair and fixed bias, where the Princeton has the cathodyne PI with the trem bias. Is this why?

[echuta13]

PI is partly why. The power transformer, and output transformer are both larger in the Deluxe which should give it a bit more headroom. Speaker efficiency most likely will come into play as well. Depends on which speakers are being used in each model.

There are some other subtleties as well (voltages, choke, power filtering, ect...) which will also contribute to differences in the sound and feel of these two amps.

[Milkmansound]

the PI is really the main factor. Long tail is much better at driving the output tubes compared to cathodyne.

[xtian]

And yes, fixed bias is more efficient than cathode bias, I understand.

[Firestorm]

Both are fixed bias and both have a fair amount of gain on tap, but the Princeton drives the signal in only one "direction" (and it's the stage with NFB applied). The Deluxe picks up only 2x or 3x in the reverb mix stage and then adds gain in the PI. They are very different sounding amps.