DTA-100a Amplifier direct power 12 volt

[pja]

Can I run this amp on straight 12 volt power with out damage to the amp?
I realize this will reduce output.
Thanks

[dthomas]

Can I run this amp on straight 12 volt power with out damage to the amp?
I realize this will reduce output.
Thanks

Sure it won't care actually it will be less offensive to the amp since it has to dissipate less power.

[rvsixer]

Rated power is 24V@5A. Last time I checked, in general halving the voltage doubles the current for the same power output, to me that means increased chance of smoke ???

[dthomas]

Rated power is 24V@5A. Last time I checked, in general halving the voltage doubles the current for the same power output, to me that means increased chance of smoke ???

Nope 12V across an 8 ohm or 4 ohm load will dissipate 1/2 the current compared to 24V across the same load. So no reason for it too smoke. You can do the same thing with LM3886 chip amps.

[Wolf]

Yeah- I wouldn't advise it.
Wolf

[dthomas]

Yeah- I wouldn't advise it.
Wolf

Not sure why the chip is rated to work at 12V to 35V. He may need to adjust the feedback resistor but that is highly doubtful at worst case he loses some gain. Lower voltage won't cause an increase in current since the output load is not reduced. It is rated for an 8 or 6 ohm load. If he reduces the load significantly it could but that would happen if he used a 24V supply and even faster. It won't have as much power output as it would with 24V but it will work.

[dthomas]

Rated power is 24V@5A. Last time I checked, in general halving the voltage doubles the current for the same power output, to me that means increased chance of smoke ???

Actually if you halve the voltage into the same load the current goes down. In order to get current to go up you have to lower the load resistance or increase the voltage. Since he is lowering the voltage and keeping the same load, current will go down of course power output will also. But he already knew that.

On a tripath amp you have a feedback resistor that controls gain. Since it is already sized for a 24V supply he will lose gain. If he wanted to change the value of that feedback resistor he could increase the gain but he is not doing that either.

[rvsixer]

...12V across an 8 ohm or 4 ohm load will dissipate 1/2 the current compared to 24V across the same load.

True.

I guess everyone missed the at the same power output part. In my experience the DTA-100 already puts out a limited amount of clean power with the 24V brick. I could only imagine it with 12V, keep cranking up the gain in an attempt to get more out of it, and over amping it. Just a different POV from an high voltage/lower current/lower heat for the same job advocate.

[ROTECH]

Didnt ohms law figure this all out for us?

[dthomas]

True.

I guess everyone missed the at the same power output part. In my experience the DTA-100 already puts out a limited amount of clean power with the 24V brick. I could only imagine it with 12V, keep cranking up the gain in an attempt to get more out of it, and over amping it. Just a different POV from an high voltage/lower current/lower heat for the same job advocate.

No this is the first mention of the same power output. It has been pretty clearly stated that it won't have the same power output since gain is limited by the rail voltage and the feedback resistor with this device if you halve the rail voltage it will reduce gain. The question was would it work and the answer is it will but at lower power and no chance of smoke as you implied. In order to increase the current by a significant amount you would have to increase the gain by changing the feedback resistor inside the amp. No one discussed changing anything in the amp circuit just the voltage supplied to it. Which according to ohm's law won't increase the current through the amp.

[1100xxben]

True.

I guess everyone missed the at the same power output part. In my experience the DTA-100 already puts out a limited amount of clean power with the 24V brick. I could only imagine it with 12V, keep cranking up the gain in an attempt to get more out of it, and over amping it. Just a different POV from an high voltage/lower current/lower heat for the same job advocate.

Increasing the gain still won't allow the amplifier to reach any higher maximum output (unless you have a very weak input signal), it just requires a lower input signal to reach the maximum output power. The amplifier gain is a voltage gain, not a power output setting. Let's assume you're driving a speaker with a 1 watt signal. You shouldn't notice any difference in output if you change the input voltage from 24V to 12V (assuming the amplifier will still operate normally at 12V). You're going to be limited by the voltage rails. I believe that almost all (if not all) these "class-T" amps do not have an internal supply to regulate the voltage rails. This is why the amplifiers have a higher power output with a higher input voltage. So, the rail is determined by what input voltage you provide. As dthomas already said, powering the amp with 12V instead of 24V is only going to decrease the voltage rail and will not allow the amp to put out full power (because your load, the speaker, is a constant impedance regardless of the voltage applied), and it should decrease the current draw significantly, not increase it. If any of these amps were to have an internal, regulated switching supply to boost the input voltage, then decreasing the input voltage would increase the current, because the amplifier would then become a constant power load.