To avoid analysis paralysis and getting stuck trying to design an amp that's all things to all people, I realized I needed to formalize my design goals.
- Class A, Single Ended design
- Output: > 3 Watts per channel
- Overall power consumption: < 50 Watts
- Heater power consumption: < 20 Watts (6B4G: 2 x 6.3 = 12.6 Watts)
- THD (total harmonic distortion): < 5% (ideally < 3%)
- Power tube cost: < $70 each (rules out 300B, 45, etc.)
- And of course, amazing sound
50 Watts of input power is rather low for most power amps, especially a tube amp, let alone a Class A single ended one. My power consumption goals are not just to produce a "greener" amp. It seems silly to consume power just to turn it into heat. I've seen many amps with huge power resistors (10 to 25 watt) for biasing the power tube or in a DC heater circuit to trim the voltage gained via the rectification. I believe, if you design for the right voltages, you generally shouldn't need to use big honkin' power burning resistors to trim it down.
Also, I'm building at least one of these amps for my friend who will be living off the grid via photovoltaic solar in New Mexico. I'd like this amp to make as little of a dent in his daily collection of power as possible.
No comments:
Post a Comment