gt4586c@prism.gatech.edu (WILLETT,THOMAS CARTER) (09/20/90)
I was recently perusing this month's Stereophile, and listed among the specs for the Audio Research Classic 60 power amplifier was its idle power consumption. This 60 Wpc amp draws 370W at idle. That's far more than your refrigerator draws when its running. At this rate, you can expect to pay about $20 per month just to keep your amp warm and ready to go. Since I see this as a needless waste of resources and a contribution to the contamination of our planet, I must ask if it is really necessary for a class A amp to draw this much power at idle? Is it not possible for it to have an idle mode during which it draws just enough current to keep the tubes happy and warm? By way of comparison, my class AB Adcom GFA-555 (200 Wpc) draws "only" 78W at idle. Would anyone care to comment on the ecological unsoundness of Class A amps and any possible remedies? -- thomas willett Georgia Institute of Technology, Atlanta gt4586c@prism.gatech.edu "Violence is the last refuge of the incompetent." - Salvor Hardin (Foundation)
tomp@vicom.com (Tom Pohorsky) (09/22/90)
>Audio Research Classic 60 power amplifier draws 370W at idle. >That's far more than your refrigerator draws when its running. >is it really necessary for a class A amp to draw this much power at idle? If a Class A amp in "on" and ready to operate, it will be drawing bigtime power, by the very nature of class A. There are a few companies that recognize the waste in this, and have an "idle" mode that keeps the machine warmed up without drawing the big power that class A bias warrants. Counterpoint maybe ?? Anyone know specific brands/models that do this ?? -- ames!vsi1!tomp tomp@vicom.com
ed@maxed.amg.com (Ed Whittemore) (09/24/90)
In article <6535@uwm.edu> tomp@vicom.com (Tom Pohorsky) writes: >>Audio Research Classic 60 power amplifier draws 370W at idle. >>That's far more than your refrigerator draws when its running. >>is it really necessary for a class A amp to draw this much power at idle? > >If a Class A amp in "on" and ready to operate, it will be drawing >bigtime power, by the very nature of class A. There are a few >companies that recognize the waste in this, and have an "idle" >mode that keeps the machine warmed up without drawing the big >power that class A bias warrants. Counterpoint maybe ?? Anyone >know specific brands/models that do this ?? > The solution here is to get a variac, and step down the voltage to the amps about 75%, or say 30 volts. You also protect the tubes from the on/off transients. For solid state equipment I don't know what you would do. Anyway, after listening to some high powered Class A amps such as a Krell KSA-250 and VTL Ichibans with only 1/2 hour of warm-up vs. a full day I can't say that there is too much, or any, difference in sound. Your mileage may vary. So I don't think the clear inefficency of Class A amplification poses either a practical or ethical problem--it is OK to turn the equipment off/bring down the voltage, and the extra pennies burned while playing music (it is only pennies), are more than compensated for by Class A sound. -- Ed Whittemore uunet!maxed!ed ed@maxed.amg.com American Micro Group, Inc. 201-944-3293