AC Power Regeneration anybody?

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The following is taken from Madrigal's literature.

AC Power Regeneration

"The No33 Reference Monaural Amplifiers employ a revolutionary technique called AC power regeneration: the DC supply feeding the voltage gain stages is derived from an AC source generated within the device itself. This technique is expensive but very effective. In the No32 Reference Controller, a 400Hz oscillator generates the AC source for the preamplifier's audio power supplies (replacing the 50/60Hz reference provided by the local utility).

One advantage that 400Hz offers over 60Hz is that transformers are more efficient (they generate less heat) at the higher frequency. Another advantage is that filter capacitors are refilled more quickly, leading to a smoother supply of DC from the filter capacitors. Equivalent filtering from a 60Hz supply would require much larger capacitors (with higher Effective Series Resistance at high frequencies).

The 400Hz oscillator supplies an input signal to separate left and right channel power supply amplifiers. The oscillator amplifier outputs, in turn, supply clean, stable (400Hz) power to discrete DC regulators located in the adjacent left and right towers. Each of these towers contains a completely independent power supply; each powers a single preamplifier channel independently."

I was thinking about building stand alone unit, based on the above principle, supplying clean AC power to my source components.

Does anybody know links or schematics that might be helpful? As always your assistance is greatly appreciated.:)
 
First you will have to build a power amplifier that will handle the required voltage swing. Then find a high quality oscillator to drive the amplifier. The amplifier should also have some form of overcurrent protection to protect from shorts.
I use a PS Audio 600 with great results. This will be quite an undertaking but the results are worthwhile or just get a PS Audio.
I can hear cries of SPAM from Harry

Jam
 
400 hurts

HPotter,

IMHO you are wasting your time. Make a good clean PSU to start with and don't worry about the 400 hz stuff. For one thing, rectified 400 Hz is 800 Hz which is far more audible that 120 Hz. Second, you should use 400 Hz transformers. 60 Hz transformers will get hotter when run at 400 hertz because there are more eddy current losses in the laminations.
 
AC Power Regeneration anybody

400Hz will require better transformers than the usual power tranformer. I have used the output transformer from a very good 200 watt tube amp and have gotten better sound than from a very good 1000 watt Bicron toroid power transformer even for 60Hz regeneration. There are other frequecies than 60 Hz involved when the voltage gets rectified. This is not as big a project as you might think. Check out the PS audio website for information on the benifits of AC regeneration.

H.H.
 
Re: Power regeneration

HarryHaller said:
Used 797 op amp 60Hz oscillator, one channel of regular stereo amp and power transformer for voltage step up. Sounded awsome but I need to fix power amp which was under heatsinked. Highly recommended.
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The output transformer seems very important. The 230V PS 300 is compromised by its output step up transformer, perhaps optimised for 60Hz areas. The multiwave patterns has less effect than expected. The transformers are also noisier than is desirable and must be damped.

I have found the same with a Japanese unit, stepped up to 230V. Despite a well wound step-up, there is a strange colouration to the sound from this. The Accuphase units which use a form of cancellation sound best.
 
Peter,

A good choice might be a Wein-Bridge oscillator. Years ago Audio Elecrtonics published a design for a very low distortion oscillator. If you cant find it let me know and I will try to find it.

Harry and Jocko might be a good resource for oscillator designs, but as usual you might have to bribe them.

Jam

P.S. I would make the oscillator variable from 60 to 400 Hz.
 
jam said:
Peter,

A good choice might be a Wein-Bridge oscillator. Years ago Audio Elecrtonics published a design for a very low distortion oscillator. If you cant find it let me know and I will try to find it.

Harry and Jocko might be a good resource for oscillator designs, but as usual you might have to bribe them.

Jam

P.S. I would make the oscillator variable from 60 to 400 Hz.
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The R53 thermistor takes a longish time to settle in this design. Not suitable fpr powering a mains suply. We need a stable, fast acting oscillator.
 
Fmak,

In this design I don't see a slight drift in frequency as much as a problem. All we need is a pure sine wave. There are several modifications to the Wein-Bridge circuit that improve its performance . I recall the use of a fet in place of a thermistor or light bulb.

On the other hand I am open to any suggestions you may have to help Peter out.

Jam
 
paulb,

Thanks for the excellent link. Seems to cover all the bases with regard to the Wein Bridge oscillator.
I see simplicity and low distortion as the key here as we are not trying to drive a turntable or device that is locked on to a specific frequency.
I still will have to say that even with a turntable I have used a simple Wein-Bridge oscillator and was not able to detect the slight speed drift on turn on.

Jam
 
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