hack@math13.math.umbc.edu (05/09/91)
I have a question about the power supplies used in high power hi-fi audio amplifiers. I would assume that the power supplies are voltage regulated. The question is can switching power supplies be used or are linears required, assuming the power supply will fit into the same box. Also, what insolation and sheilding must be there to prevent hum and noise pickup. Thank you very much in advance, J. Hack
john@newave.UUCP (John A. Weeks III) (05/10/91)
In article <1991May9.120758.20464@umbc3.umbc.edu> hack@math13.math.umbc.edu writes: > I have a question about the power supplies used in high > power hi-fi audio amplifiers. I would assume that the power > supplies are voltage regulated. The question is can switching > power supplies be used or are linears required, assuming the > power supply will fit into the same box. For the most part, the power supplies are voltage regulated linear power supplies. The key factor is the peak current available. Musical peaks may come along that surpass the current capacity of the power supply itself, so most high end amps have huge capacitors for current reserve. For the most part, switching power supplies are too noisy to be used for audio amps, and switching supplies like well behaved steady loads, not something like music. There are amps available with wierd power supplies, but they tend to be for specialized purposes. Class C amps work good for voice, but not for music. They are used because they are very efficient. Soundcraftsman used to advertise something called class 'H' amps. These were basically two stage amps that had a quality low power amp plus an extra high power stage. The high power stage could not run continious duty, so it was used only for peaks. The end result was a quality low power amp the acted and sounded like a much more powerful amp. Carver designed the most unique audio amp that I ever encountered. It is advertised as a magnetic field amp. It had a high power rating but was far lighter and smaller than conventional amps. What I suspect is that Carver used the input signal to somehow modulate the power supply. -john- -- ============================================================================= John A. Weeks III (612) 942-6969 john@newave.mn.org NeWave Communications, Ltd. ...uunet!tcnet!newave!john
whit@milton.u.washington.edu (John Whitmore) (05/11/91)
In article <822@newave.UUCP> john@newave.mn.org (John A. Weeks III) writes: >Soundcraftsman used to advertise something called class 'H' amps. >These were basically two stage amps that had a quality low power amp >plus an extra high power stage. The high power stage could not run >continious duty, so it was used only for peaks. The end result was >a quality low power amp the acted and sounded like a much more powerful >amp. The 'class H' amps started with Hitachi, I think. Most of Carver's units use this same principle (and the highest power ones have THREE positive and THREE negative power supplies). Amplifier efficiency depends on the difference of the power supply voltage and the output voltage; on the average, that efficiency goes WAY up when there are several possible power supplies (and the least of them is used until the signal demands more...). John Whitmore