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-   -   PWM Power Supplies in Car Amps (http://www.diyaudio.com/forums/car-audio/41274-pwm-power-supplies-car-amps.html)

Mikett 21st September 2004 04:05 AM

PWM Power Supplies in Car Amps
 
Do these power supplies regulate output voltage?

Evan Shultz 21st September 2004 05:06 AM

it depends. it can be either way. however, if they are switching it is far more likely that they will be regulated than if it was a linear supply. and since a car amp has to run higher than 12V rails to provide decent power, and a car supplies DC, car amps have to use a switching supply. i feel pretty confident in saying that most car amps are regulated, and all the ones i have dealt with are.

SupraGuy 21st September 2004 05:44 AM

Well, Pulse Width Modulation suggests that the supply regulates voltage by varying (or modulating :) ) the signal to the transformer. Given that information, I'd say yes, however, since I've seen unregulated supplies being called PWM, I'd have to say "It depends."

thespeakerguy 21st September 2004 06:12 AM

Kinda...
 
As they are usually making dual supply voltages, you can regulate one output. It would take two separate supplies to create two regulated voltages.

The couple I've looked at seemed to use an open loop push pull supply, and were unregulated.

JZatopa 21st September 2004 06:18 PM

They use both pretty equaly. JL audio happens to make two lines of amps. The / series and the e series. The / series uses regulated power supply where as the e series uses unregulated.

eric180db 21st September 2004 10:11 PM

they are all regulated
 
some are tightly regulated and some are loosely regulated the good amps are more tightly regulated you can tell if it is by how much power it puts out at 14.4v as oposed to 12v if its the same then its a tight supply.

zagisrule! 21st September 2004 10:44 PM

Competition amps (from what I have heard) are rarely regulated because an unregulated supply can be run at 100% output all the time for maximum power. A regulated supply is "held back" so to speak, but the rails try to always stay the same by adjusting PWM.






-Matt

Mikett 22nd September 2004 02:15 PM

Generally then, the better amps are regulated.

If PWM supplies are regulated then there should be nearly minimal effects of large capacitors and power cabling on those amps. Right?

jackinnj 22nd September 2004 03:18 PM

Quote:

Originally posted by zagisrule!
Competition amps (from what I have heard) are rarely regulated because an unregulated supply can be run at 100% output all the time for maximum power. A regulated supply is "held back" so to speak, but the rails try to always stay the same by adjusting PWM.

-Matt

One of the reasons that you DO want to regulate a PWM supply is that under certain circumstances the core can go into saturation -- bad for the switching transistors since the impedance drops to zero and the transistors look into a shorted primary. (particularly if they are BiPolar). Pulse-by-pulse current monitoring can limit this.

Most SMPS like to look at a constant, or nearly constant load -- depending upon the amplifier configuration it can be great or a disaster -- the example of a really bad idea is a Class-C ham radio amplifier used for CW transmission -- a Class A amp is the other side.

All depends upon the plug and chug math which spits out the inductance values, themselves inversely related to the peak and average current demands.

djQUAN 22nd September 2004 04:43 PM

from my point of view, I think non regulated SMPS's are cheaper and simpler to build. a reason cheap amps use them. I have heard that non regulated ones tend to be more efficient. I have not proven it though.

a regulated PSU is a bit more complex or very complex depending on the design, and it needs additional filtering on the output of the PSU. but the rails would be stiffer.


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