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Using a mono-block amplifier as mains power for another amplifier

post #1 of 19
2/19/13 at 11:08am
Thread Starter 

I was wondering it this would be possible. If there was a mono block amplifier powerful enough to deliver an output of 120 V of a 60 Hz sound wave to match the voltage and frequency of mains electricity, wouldn't you be able to use it instead of the mains for a non-fluctuating clean AC signal? I am not saying it is a sensible thing to do but would that be possible or even beneficial to a sound system? Let me know what you think.

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post #2 of 19
2/19/13 at 11:37am

Would have to be at least a 3600 W power amp (into 4 ohms) and while it could work it is patently absurd. tongue.gif

 

Just get a mains conditioner if you have proof that your mains supply is bad. Or an amp with a better power supply.


Edited by xnor - 2/19/13 at 11:42am
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post #3 of 19
2/19/13 at 7:09pm
Quote:
Originally Posted by xnor View Post

Would have to be at least a 3600 W power amp (into 4 ohms) and while it could work it is patently absurd. tongue.gif

 

Just get a mains conditioner if you have proof that your mains supply is bad. Or an amp with a better power supply.

But then you'd need another amp to drive the amp to drive the amp to drive the amp.

 

Hey, if you took the last amp's output and really really fast...shoved it into the first amps mains, the whole rig would just keep running on free energy right?  No?  Shucks.

 

To be serious, amps have been used to drive some strange stuff, including motors to achieve variable speed tape drives.  It's just not really an efficient way to do it. As a kid I lit up some lightbulbs with an audio amp.  Even burned a few out that way. Lightbulbs, not amps. 

 

Related, sort of,  old AM radio transmitters used to use audio power amps to modulate the plate voltage of the final RF amplifier to achieve amplitude modulation.  That meant if you had a 1000 watt transmitter, you had a 1000 watt (tube!) audio amp.  The idea got really messy at high powers like 50Kw, and other methods were quickly found, but low power rigs up into the 1970s used big audio amps as high-level plate modulators.  

 

So, that's kind of like an amp as part of a power supply for another amp.

 

(footnote: the tube in my avatar is an 833A, and was used in just that sort of rig)

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post #4 of 19
2/19/13 at 7:24pm

There are many audio speaker amplifiers like that. Here's one from Cello, Performance Amplifier II, a pair of mono amps powered by mono power supplies.

 

 

The Performance Amplifier II

The Performance Amplifier is a four chassis set, comprised of two mono power supplies and two mono power amplifiers.

 

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post #5 of 19
2/19/13 at 8:18pm
Quote:
Originally Posted by wuwhere View Post

There are many audio speaker amplifiers like that. Here's one from Cello, Performance Amplifier II, a pair of mono amps powered by mono power supplies.

 

 

The Performance Amplifier II

The Performance Amplifier is a four chassis set, comprised of two mono power supplies and two mono power amplifiers.

 

Now there's a unique term! "Mono Power Supply".  

 

I think, though, that the folks at Cello are building really one audio amp and one "mono power supply" to work together, not an audio amp powering another audio amp.  In other words, the "mono power supply" isn't an audio amp at all, it's a specially designed power supply.

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post #6 of 19
2/19/13 at 8:19pm

Those monoblock power supplies output fixed voltage supply rails (DC) for the amps, right?

 

We're talking about repurposing an amplifier (amplifies whatever waveform you please, so long as it is of a certain frequency and so on) to feed the input of an amplifier's power supply (AC), simulating the wall voltage.

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post #7 of 19
2/19/13 at 8:27pm

Yes it is dc, which I'd rather have than ac.

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post #8 of 19
2/19/13 at 8:43pm
Quote:
Originally Posted by wuwhere View Post

Yes it is dc, which I'd rather have than ac.

Agreed.  The entire thread is hypothetical.  

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post #9 of 19
2/19/13 at 9:51pm

I DARE you to plug 120v DC into the back of one of your amplifiers, and see how well that goes ;) 

 

Quote:
Originally Posted by wuwhere View Post

Yes it is dc, which I'd rather have than ac.

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post #10 of 19
2/20/13 at 12:38am
Quote:
Originally Posted by El_Doug View Post

I DARE you to plug 120v DC into the back of one of your amplifiers, and see how well that goes ;) 

 

If you bypassed the power transformer things might go well, but again, hypothetical. 

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post #11 of 19
2/20/13 at 5:03pm
Quote:
Originally Posted by El_Doug View Post

I DARE you to plug 120v DC into the back of one of your amplifiers, and see how well that goes ;) 

 

 

Lol, I seriously doubt that the power supply is supplying that high of a voltage. It would be different dc voltages from the power rails of the power supply. Separating the power supply from the power amp makes them lighter, relatively, to move around, weight-wise and also dimension-wise.


Dimensions:
17.5"w / 8.5"h / 18.5"d (each of four chassis)

Shipping Weight:
72 lbs. each Power Supply
60 lbs. each Power Amp

 

But there are penalties as well, price mostly and space. BTW, I listened to these amps before, a bi-amp speaker with four pairs of these amps.

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post #12 of 19
2/20/13 at 9:48pm
Quote:
Originally Posted by wuwhere View Post

BTW, I listened to these amps before, a bi-amp speaker with four pairs of these amps.

...and?
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post #13 of 19
2/21/13 at 5:44am

In the distant past days of analog tape, occasionally a studio needed to tune a recorded instrument track to live instruments that weren't so easy to tune.  So they would use a audio oscillator, a power amplifier and a voltage step-up transformer to power the tape recorder. Then they would slightly adjust the oscillator frequency to tune the already recorded musical instrument.

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post #14 of 19
2/21/13 at 8:46am
Quote:
Originally Posted by Speedskater View Post

In the distant past days of analog tape, occasionally a studio needed to tune a recorded instrument track to live instruments that weren't so easy to tune.  So they would use a audio oscillator, a power amplifier and a voltage step-up transformer to power the tape recorder. Then they would slightly adjust the oscillator frequency to tune the already recorded musical instrument.

For an extra 10 Bonus Points, what was name of the commercially made device to do this job?

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post #15 of 19
2/21/13 at 8:48am
Quote:
Originally Posted by jaddie View Post

For an extra 10 Bonus Points, what was name of the commercially made device to do this job?

 

A computer.  cool.gif

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