FS: N.E.W. 66W Class A Amplifier (modified)

[jono1]

This is a used piece of gear - N.E.W. stands for Nirvana Electric Works.

They manufactured an outstanding 33W/channel amp that was designed to run off of four marine type lead-acid batteries, which required charge and discharge cycles, eventual replacement of the batteries, etc.

A failure of the OEM charging circuit killed my woofers, so I custom designed an outboard AC/DC power supply that actually consists of two separate supplies that can deliver 500 watts of continuous power.

This supply weighed considerably less than the batteries; is certainly more reliable, and permits continuous operation of the amplifier. It is dead quiet - I can't detect any hum on my JBL Century 100s.

A lot of craftsmanship and thought went into the modification. The "umbilical" power cable took about 2 hours alone. The front is polished brass and looks much better than my photo, which suffers from reflection.

If you want a fine example of a Class A amplifier (supposedly based on a Pass design), this is a great value at $599 plus shipping.

[jono1]

In reply to some questions:

I wish that I had been able to do a side-by-side comparison of the battery-powered amp vs. the A/C supply. To my aural memory -- which is naturally suspect -- I don't recall a difference between the two.

Does a DC power supply actually produce more "magic" -- or is a more hype -- or a combination of the two?

In my opinion, the chief benefit of batteries is reduced noise. Like most engineering choices, there are alway compromises. There is no doubt about the drawbacks of a battery supply, e.g. 1) have to charge / discharge and can't run continuously; 2) the battery pack was incredibly heavy and unwieldy, and 3) lead-acid batteries have a typical life of 2-3 years.

I think that low noise (in the power supply) is most important in high-gain, low-level circuits such as preamplifiers, and that is where a battery supply should shine.

A Class-A amplifier has a substantial quiescent current (by definition) and I think this makes it a bit more immune to transients, but I may be wrong.

In any event, the power supply consists of two separate channels. There are two toroids -- Plitrons, I believe -- that provide 225VA at 50 Hz. or 250W each at 60. Each toroid produces about 38VCT. The A/C is rectified by hefty bridge rectifiers, and then filtered by a pair of 18,000 UF capacitors per channel.

There are bleeder resistors and each rail is separately fused. I made an umbilical cord to connect the two chassis, and there is plenty of wire allocated for grounds or power returns.

I think $599 is a great price for what you are getting.