Several Questions

Guest · Posted: Mon Apr 21, 2003 6:45 pm Post subject: Several Questions

I am currently planning on buying either the THD Univalve or Bivalve amp. These have the ability to swap tubes to any of your choice (one power and two pre amp on the univalve, 2 power and 2 preamp on the bivalve) and i was wondering what kind of sound each tube will give you? Also, it lacks a gain switch but comes with two inputs (high gain "rock" and low gain "roll"). If i buy an ABY switch and plug my guitar into it, connect the high gain input of the amp to output A and low gain input to out put B on the switch, would i be able to successfully change channels? Would the power of the amp decrease because the two inputs would be taken up?

One more thing....i have the choice of what cab i can get....what sounds would each cab give (single 12 two 10 two 12 4-10 4-12?)

TimC · Posted: Mon Apr 21, 2003 9:01 pm Post subject:

Your switching plan should work fine as long as it's A or B and not A and B. I went to the websight and listened to the demos, but since they added delay and reverb in the mix, it's hard to tell what the pure amp sounds like. There are a few "magic" amps that sound good with any guitar or speaker combination, but not many. The attenuator is supposed to let you crank up the volume until the power section starts to "sing", and still keep the overall volume at level that won't bring the law. A good rule of thumb on speaker wattage is to keep the combined wattage of the speakers close to the rated output of the amp. Part of that cello/sax sound we love comes from speakers near meltdown. The single power tube option is class A (think Fender Champ or Vox AC series). Half the power of two power tubes, but more harmonic overtones. The other option with both tubes is AB (push-pull) I imagine but it may be a more powerful class A. Great distortion comes from the power section. One night I was fooling with my Twin when a neighbor called and said he was coming with his shotgun. His wife was crying and yelling at him in the background, so I belived him. No more cello/sax, no sir.

TimC · Posted: Tue May 13, 2003 8:07 am Post subject: Senior brain fade

I realized that my advice to keep the wattage of the speakers close to the output of the amp was not the best. I've tailored the amps I play at my house to sound the best at low volume and clean settings. If you crank an amp wide open and push the output into a square wave (distortion), with a cheap speaker you should have 3x the rated output. With a better made speaker, 2x. This is rated peak wattage, not rms. Rms wattage at the rated output should be fine with a good quality speaker.
Concerning the cabinet choices, those with the most speaker area will move the most air. I can't tell much difference between the different configurations as far as tone. I think quality has more to do with tone than any certain grouping. Multiple speakers offer a safety net in case of an open circuit. If a single speaker looses continuity and you don't notice it, the amp could fry in about 30 seconds. Multiple speakers would result only in an impedance mis-match.