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.
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."
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.
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.
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.
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.
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.
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
-Matt
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?
If PWM supplies are regulated then there should be nearly minimal effects of large capacitors and power cabling on those amps. Right?
zagisrule! said:
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.
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.
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.
djQUAN said:
Efficiency ? There's no reason that efficiency would be any different. The additional components are a pair of sensijng resistors and a photo-coupler.
I have read (again) from my mag, about 2 years ago an article about car amps written by a car amp designer.
it may sound simple. this is what the guy said.....
regulated PSU's need high quality low ESR caps, output chokes and optically isolated feedback for regulation. unregulated supplies are less expensive because they do not need output chokes and feedback circuitry and since unregulated designs have 50-50%duty cycle all the time, there is much less ripple current and cheaper caps can be used.
for the pros and cons of regulated and unregulated supplies, I think I have to quote this directly.
"Some designers try to keep their supplies regulated down to battery voltages as low as 9.5 volts. the supply compensates by increasing current. the current increases dramatically at the lower voltages. because of the higher currents at lower voltages, the supply efficiency drops further, requiring even more current. at higher voltages, the pulse width reduces, causing increased ripple current. this high current creates heat in the filter capacitors and can destroy the capacitor's electrolyte. some manufacturers do not use capacitors of sufficient quality for this range of of regulation. these amplifiers may not perform up to specification just one year after installation. also, the extra current at low voltages is extra hard on a battery that is already suffering. so we recommend that amplifiers stay in regulation down to about 11-11.5 volts.any properly working charging system can easily keep the battery voltage well above this."
-robert zeff, car audio and electronics january 2002.
it may sound simple. this is what the guy said.....
regulated PSU's need high quality low ESR caps, output chokes and optically isolated feedback for regulation. unregulated supplies are less expensive because they do not need output chokes and feedback circuitry and since unregulated designs have 50-50%duty cycle all the time, there is much less ripple current and cheaper caps can be used.
for the pros and cons of regulated and unregulated supplies, I think I have to quote this directly.
"Some designers try to keep their supplies regulated down to battery voltages as low as 9.5 volts. the supply compensates by increasing current. the current increases dramatically at the lower voltages. because of the higher currents at lower voltages, the supply efficiency drops further, requiring even more current. at higher voltages, the pulse width reduces, causing increased ripple current. this high current creates heat in the filter capacitors and can destroy the capacitor's electrolyte. some manufacturers do not use capacitors of sufficient quality for this range of of regulation. these amplifiers may not perform up to specification just one year after installation. also, the extra current at low voltages is extra hard on a battery that is already suffering. so we recommend that amplifiers stay in regulation down to about 11-11.5 volts.any properly working charging system can easily keep the battery voltage well above this."
-robert zeff, car audio and electronics january 2002.
most of the losses take place in the power diode and the power transistor (switch), followed by the snubber, capacitor ESR and thermal and other losses in the magnetics -- i believe that most of the transistor switching losses occur during the transition period.
the graphs of efficency which I have seen show efficiency somewhat like a parabola -- low at low currents, rising to some optimal level, then falling at high currents -- these graphs can be found on both the Nat Semi and Linear Tech websites (I haven't checked TI).
if you don't regulate (i.e. maintain a constant duty cycle) the output voltage will track the input voltage -- it would be interesting to put a data-logger on the cigarette lighter output jack to see how this varies during the course of a trip !
one thing which we don't have to do as DIYr's is conform our project ot some linear programming optimization model -- we don't have to be particularly "green" if we feel that Class-A is best.
the graphs of efficency which I have seen show efficiency somewhat like a parabola -- low at low currents, rising to some optimal level, then falling at high currents -- these graphs can be found on both the Nat Semi and Linear Tech websites (I haven't checked TI).
if you don't regulate (i.e. maintain a constant duty cycle) the output voltage will track the input voltage -- it would be interesting to put a data-logger on the cigarette lighter output jack to see how this varies during the course of a trip !
one thing which we don't have to do as DIYr's is conform our project ot some linear programming optimization model -- we don't have to be particularly "green" if we feel that Class-A is best.
interesting? I have a digital voltmeter always plugged in into the cigarette lighter socket. my charging system varies from 12.8V to 14.2V. I know some causes of the varying voltage, the other times when it varies, I have no idea.
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