Home |
Search |
Today's Posts |
#1
Posted to rec.audio.car
|
|||
|
|||
Regulated power supply in car amp?
Hello! I'd like to get opinions about the pros and cons of regulated
PWM supplies in car amps, in the real world. Thanks! -- Eric (Dero) Desrochers http://homepage.mac.com/dero72 Hiroshima 45, Tchernobyl 86, Windows 95 |
#2
Posted to rec.audio.car
|
|||
|
|||
Regulated power supply in car amp?
Eric Desrochers wrote:
Hello! I'd like to get opinions about the pros and cons of regulated PWM supplies in car amps, in the real world. The one major drawback would be the additional size, as well as probably heat generatred, as they cram enough stuff into most HUs as it is. I can't think of any REALISTIC benefits that would out-weigh that. |
#3
Posted to rec.audio.car
|
|||
|
|||
Regulated power supply in car amp?
well the obvious benefit is constant power output, regardless of input voltage. Disadvantages include no gain of power at higher voltages and the amount of current drawn increases when voltage drops. So it's kind of a circular problem at that point. voltage drops because current draw is too much, but the amp sucks more current because the voltage is dropping. -- KU40 |
#4
Posted to rec.audio.car
|
|||
|
|||
Regulated power supply in car amp?
|
#5
Posted to rec.audio.car
|
|||
|
|||
Regulated power supply in car amp?
Kevin McMurtrie wrote:
They're all regulated or controlled to some degree, but not solid like a preamp or computer supply. With a properly balanced amplifier circuit, ripples and dips in the power rails don't cause any problems. It's more efficient to drain the amp rail capacitors a bit rather than try to pass enormous surges through the whole system. Despite not holding a constant voltage, audio power supplies are designed with control over the output. Home systems sometimes have weak magnetic coupling in the power transformer so that the power rails can droop on low impedance loads without frying parts. Car amps will adjust the voltage based on current draw and temperature to avoid overheating. You'll not likely find a high power car amp that doesn't have a PWM power supply. It's the simplest and most effective design these days. Chips handle the complexities like regulation feedback, avoiding transformer saturation and bias, bootstrapping, soft-start, thermal overload, current overload, and MOSFET driving. Thanks for the info, all! It goes with what I read elsewhere and with my own knowledge of electronic (which I studied). So an amp that is fully regulated (models by xtant, JL Audio and Alto mobile comes to mind) will hold its power rating better despite varying supply voltage. Since audio power output is often quoted at an high supply voltage of 14.4 volts, a regulated model might keep its promise better at a more realistic 13.8 volts, for example. Or 12.2 volts... Now a more acute question : do you think a regulated supply will affect the overall amp efficiency compared with a similar, unregulated model? FInally, a rave and a rant! I think the new CEA 2006 standardisation have cleared A LOT of fluff and clutter in the spec sheets of equipment and I APPLAUDE those responsible for its creation and the manufacturer who apply them! OTOH, every manufacturer of class-D or D-variant amps like to talk about the great efficiency of their amps but fail short of stating the actual figure in %. Few reviewers actually post those figures either. I find this info to be more relevant than say the damping factor (which is already an order of magnitude higher than what is needed in most case) and it's virtually impossible to find... If you happen to have numbers for Premier PRS-D2000T or Kenwood KAC-9109D... Thanks! -- Eric (Dero) Desrochers http://homepage.mac.com/dero72 Hiroshima 45, Tchernobyl 86, Windows 95 |
#6
Posted to rec.audio.car
|
|||
|
|||
Regulated power supply in car amp?
Now a more acute question : do you think a regulated supply will affect
the overall amp efficiency compared with a similar, unregulated model? Ooh..... Good question. I don't think I've ever heard that asked here before (how does the efficiency of regulated amps compare with unregulated amps). My hunch (and this is a totally uneducated guess) is that efficiency would tend to be the same as both are Class AB in operation (which ultimately determines efficiency), it is only the power supply that is regulated. MOSFET |
#7
Posted to rec.audio.car
|
|||
|
|||
Regulated power supply in car amp?
MOSFET wrote:
Now a more acute question : do you think a regulated supply will affect the overall amp efficiency compared with a similar, unregulated model? Ooh..... Good question. I don't think I've ever heard that asked here before (how does the efficiency of regulated amps compare with unregulated amps). Ha! I wouldn't ask to this fine group if the info was readily available on the web! My hunch (and this is a totally uneducated guess) is that efficiency would tend to be the same as both are Class AB in operation (which ultimately determines efficiency), it is only the power supply that is regulated. MOSFET Yeah, in the case of the class AB, some more or less efficient supply might get lost in the grossly innefficient actual amplification circuits. But in the case of a class D amp, a few more % efficient PSU becomes more important. In case you haven't realized yet, i'm an efficiency freak! Regards, -- Eric (Dero) Desrochers http://homepage.mac.com/dero72 Hiroshima 45, Tchernobyl 86, Windows 95 |
#8
Posted to rec.audio.car
|
|||
|
|||
Regulated power supply in car amp?
|
#9
Posted to rec.audio.car
|
|||
|
|||
Regulated power supply in car amp?
In article , "MOSFET" wrote:
Now a more acute question : do you think a regulated supply will affect the overall amp efficiency compared with a similar, unregulated model? Ooh..... Good question. I don't think I've ever heard that asked here before (how does the efficiency of regulated amps compare with unregulated amps). My hunch (and this is a totally uneducated guess) is that efficiency would tend to be the same as both are Class AB in operation (which ultimately determines efficiency), it is only the power supply that is regulated. With an unregulated supply, the rails are higher than whats needed, so there is too much power wasted in heat, equals less efficiency. greg |
#10
Posted to rec.audio.car
|
|||
|
|||
Regulated power supply in car amp?
With an unregulated supply, the rails are higher than whats needed, so
there is too much power wasted in heat, equals less efficiency. greg Interesting. And I am not an EE so I know NOTHING about how an amp actually operates. But just so I'm clear, you are seeing that with a regulated Class AB amp, the rails are NOT higher than needed? I just want to be sure we are comparing apples to apples. MOSFET |
#11
Posted to rec.audio.car
|
|||
|
|||
Regulated power supply in car amp?
Interesting. And I am not an EE so I know NOTHING about how an amp
actually operates. But just so I'm clear, you are seeing that with a regulated Class AB amp, the rails are NOT higher than needed? I just want to be sure we are comparing apples to apples. MOSFET I meant "saying" not "seeing". The reason I ask is that I thought with ALL Class AB amps the rail voltage was ALWAYS higher than what was needed (regardless of regulated vs. unregulated). This, of course, is the KEY thing that separates more efficient amp designs (Class D, Class T, etc.). MOSFET |
#12
Posted to rec.audio.car
|
|||
|
|||
Regulated power supply in car amp?
In article , "MOSFET" wrote:
With an unregulated supply, the rails are higher than whats needed, so there is too much power wasted in heat, equals less efficiency. greg Interesting. And I am not an EE so I know NOTHING about how an amp actually operates. But just so I'm clear, you are seeing that with a regulated Class AB amp, the rails are NOT higher than needed? I just want to be sure we are comparing apples to apples. The rails are always higher than needed. When you speak of regulation, the rails don't have to be smart, or follow along to a certain extent, with the music. The rails could be regulated to a certain value and stay there, but that would be stupid to do when you can control the rail so it for example, stays 5-10 volts above the music waveform. Some systems have done this with two or three discrete rail voltages, have been mostly home amplifiers. The more voltage differential between the rail and the music waveform, just produces more I times E wasted power across the transistors in the amplifier stage. The regulated power supply is an infant form of switching amplifier, where the power supply is basicall acting also as the amplifier stage directly, so that 5-10 voltage differential does not exist at all, except for the voltage across the mosfets which is pretty small. We eliminated the transistors and went to use mosfets because of their fast switching speeds. I had one of the first amplifiers that had transistor switching power supply, It use a slow swiching speed campared to the mosfets. greg |
#13
Posted to rec.audio.car
|
|||
|
|||
Regulated power supply in car amp?
In article ,
"MOSFET" wrote: Interesting. And I am not an EE so I know NOTHING about how an amp actually operates. But just so I'm clear, you are seeing that with a regulated Class AB amp, the rails are NOT higher than needed? I just want to be sure we are comparing apples to apples. MOSFET I meant "saying" not "seeing". The reason I ask is that I thought with ALL Class AB amps the rail voltage was ALWAYS higher than what was needed (regardless of regulated vs. unregulated). This, of course, is the KEY thing that separates more efficient amp designs (Class D, Class T, etc.). MOSFET A switching power supply can't raise the rails in the 1/80000 second that could be needed. Switching power supplies that track the output always risk clipping during a sudden noise. Class D amps chop the rails into a fractional signal that's filtered using a nearly lossless LC filter. The negative feedback is loop is really tricky because the amp's gain is proportional to the rail voltage and the chopped output lags the input. It's why most Class D amps are subwoofer grade only. Class H and variants are a Class AB amp with a Class B amp pushing its power rails outward as needed through capacitor coupling. It's more efficient but the high current pulsing in the power rails can cause minor audio quality problems. |
#14
Posted to rec.audio.car
|
|||
|
|||
Regulated power supply in car amp?
Thank you for your thorough explanation. I really appreciate it!
MOSFET A switching power supply can't raise the rails in the 1/80000 second that could be needed. Switching power supplies that track the output always risk clipping during a sudden noise. Class D amps chop the rails into a fractional signal that's filtered using a nearly lossless LC filter. The negative feedback is loop is really tricky because the amp's gain is proportional to the rail voltage and the chopped output lags the input. It's why most Class D amps are subwoofer grade only. Class H and variants are a Class AB amp with a Class B amp pushing its power rails outward as needed through capacitor coupling. It's more efficient but the high current pulsing in the power rails can cause minor audio quality problems. |
#15
Posted to rec.audio.car
|
|||
|
|||
Regulated power supply in car amp?
In article
, Kevin McMurtrie wrote: In article , "MOSFET" wrote: Interesting. And I am not an EE so I know NOTHING about how an amp actually operates. But just so I'm clear, you are seeing that with a regulated Class AB amp, the rails are NOT higher than needed? I just want to be sure we are comparing apples to apples. MOSFET I meant "saying" not "seeing". The reason I ask is that I thought with ALL Class AB amps the rail voltage was ALWAYS higher than what was needed (regardless of regulated vs. unregulated). This, of course, is the KEY thing that separates more efficient amp designs (Class D, Class T, etc.). MOSFET A switching power supply can't raise the rails in the 1/80000 second that could be needed. Switching power supplies that track the output always risk clipping during a sudden noise. Class D amps chop the rails into a fractional signal that's filtered using a nearly lossless LC filter. The negative feedback is loop is really tricky because the amp's gain is proportional to the rail voltage and the chopped output lags the input. It's why most Class D amps are subwoofer grade only. Class H and variants are a Class AB amp with a Class B amp pushing its power rails outward as needed through capacitor coupling. It's more efficient but the high current pulsing in the power rails can cause minor audio quality problems. Actually, there are two kinds of Class H. The compact version uses diodes and capacitors and a Class B amp to raise the rails, more like a Class G. Another version has one Class B or D amp driving the common line of an isolated power supply for another Class AB amp. The second has good audio quality but it requires one extra power supply per channel and it's only efficient if the first amp is Class D. http://en.wikipedia.org/wiki/Electronic_amplifier |
Reply |
Thread Tools | |
Display Modes | |
|
|
Similar Threads | ||||
Thread | Forum | |||
A Strawman, Constructed and Destroyed-Williamson's Folly? | Audio Opinions | |||
Power supply question | Audio Opinions | |||
KISS 121 by Andre Jute | Vacuum Tubes | |||
here is how firewire ports fail | Pro Audio | |||
ATX Power Supply | Pro Audio |