[Patrick Turner]

On Feb 8, 4:10*am, Big Bad Bob BigBadBob-at-mrp3-
wrote:
On 02/02/11 19:10, Patrick Turner so witilly quipped:

ARC should never ever let any amp out the factory gate unless it is
equipped with an easily adjustable mains voltage selector switch, with
selections of 100V, 110V, 120V, 220V , 230V 240V and 250V. This isn't
difficult in such highly priced amplifiers.

although my transformer experience only extends to things like unwinding
a few burnt ones to see if I could fix them (no) and selecting low
voltage transformers for solid state power supplies "intentionally
overrated" to prevent burnup, I would expect that a properly designed
power supply transformer capable of 110/220 would theoretically NOT be
that much more expensive to make if it contained a few MORE taps, like
120/240 at the very least (if not all of the ones you mentioned). *And
yeah, the extra dollar or two for a high end amp should be expected.

Mains trannies designed by ARC or perhaps Magnequest who may their sub-
contractor are generally sturdy things and can survive having +/- 15%
higher or lower voltages and currents than design centre values.
But the electronics suffers if mains voltages are away from design
centres.

But I'm still having a bit of trouble seeing why a transformer power
supply would be superior to a switcher, especially when a switcher would
produce the same output voltages REGARDLESS of the input voltage, and
would most likely cost less, weigh less, etc. (unless large chunks of
iron for the power supply have a nostalgia factor that I"m somehow
missing). *Anyway I probably wouldn't be able to convince the amp
makers, but it's an interesting point anyway (I think so).

I don't know where a +450Vdc x 1Amp dc regulated SMPS can be found.
Try Googling, and perhaps like me you cannot find anyone building/
using such a PSU and probably you won't find a schematic either.

Many high end professional amps for SS have SMPS with rails of +/-
240V for 5kW amps. One would think 480Vdc is also doable.

But the high end press is always scared of anyone using SMPS because
switching artifacts and high level RF signals get into the audio
signal path or become difficult to supress. But Halcro use SMPS also.
No schematics though.

So SMPS technology has yet to be accepted for high end tube and much
other SS audio amps among fussy buyers.
Its easy to say, just use a SMPS, and in theory its valid, but I am
not going to bash my head against a world which is recalcitrantly
stubborn.
Old fashioned linear PSUs are extremely rugged and unlike my
computer's 300W SMPS, they won't become un-repairable if struck by a
very small amount of lightning. That happened last year and cost me a
new PSU and a MB and later the HD.

Besides people who own ARC or other absurdly heavy expensive amps
don't want a thief running away with one. They want the thief to
struggle, and drop the fukkin amp on his foot, then leave it alone to
limp to a hospital.

Patrick Turner.