fender princeton chorus amp

[T-bone]

hi guys, newbie, ive got a princeton chorus, that seems to want to bottom out and rumble if you turn the bass up over 4, is there a special way to test the speakers for ineficiancy? really appreciate help! T-bone.

[6267]

first, check the speakers with a ohmmeter or digital multimeter. If they're 8-ohm, they should read between 6 and 8 ohms. Four reads about 3 ohms, and 16 can read as low as 12. Then try the speakers in another amp, to see if the problem is still present. I would also try a different speaker in the original amp. If the problem does not move with the speaker, and persists despite a different speaker being installed in the amp, you have an amp problem, not a speaker problem.

There are plenty of online resources for diagnosing tube amp problems (google: tube amp problem). Some older tube amps 'fart out' on low bass, for reasons known only to the designers and/or the bastards who charged them too much for large electrolytic caps. You can fix this (unless you need more bass) by lowering some coupling cap values a bit. I'd also replace all the cathode bypass caps (if any) and verify that the caps in the tone control section (as well as resistors) are in spec.

Good luck, that should get you started...

[T-bone]

cheers for input

thanks for your input mate really appreciate it T-bone .

[Enzo]

Efficiency will have little to do with the speaker farting. The only way I know to test efficiency is to do it like the speaker makers do - apply 1 watt of 1kHz and mic it at 1 meter. Easier to look it up. But that is not why it farts.

Try something like a CD player into it. How does that sound? There will be no acoustic linking like there is with the guitar



The Princeton CHorus is a solid state amp, not a tube amp.
So there are darn few cathode bypass caps...

[6267]

Heh, thanks enzo...I saw princeton and thought "oh, tubes!".