[Patrick Turner]

On Jan 29, 4:53*am, flipper wrote:
On Fri, 28 Jan 2011 00:53:49 -0800 (PST), Patrick Turner

wrote:
snip for brevity,

In the Land of the Free aka as Home of the Brave, when the mains
voltage is is off 10--20% we use Variacs . And no need to monkey
around with unnecessary 'modifucations' .

Technicians and do it yourselfers, maybe, but the vast majority of
users do exactly what his user does: plug it in and turn it on.- Hide quoted text -

The vast majority of users are technically illiterate, through no
fault of their own.

"Technically illiterate" is a buzz phrase that has no meaning unless
qualified. Users may be "technically illiterate" about the quantum
mechanics of LED light emission but they are technically literate
enough to drive cars, operating iPods, iPhones, and many other
'technical' devices.

The astronauts who went to the moon in 1969 did not have to know how
to repair/modify or service their vehicle.
So complete technical literacy isn't needed for a moon trip.
But I bet those astronauts knew more about their rocket than the
average audiophile knows about his audio gear!!!!!!!

Most of my customers know **** all about how the amps they buy work.
If asked to describe how it all works, they cannot, and biasing is
something poorly understood and many get it very WRONG unless I make
sure it is impossible to bias any tube with too much current.

It is my duty of care to protect my customers from themselves. It is
my customers' right to obtain something they buy from me which is easy
to live with, needing almost zero understanding of anything technical,
and which will never put smoke int their loungerooms.


They cannot be blamed for buying ARC and other major "reputable" brand
names of audio gear while thinking they can use it without special
mains arrangements to get reliability if the mains voltage is 13.7%
above the labelled input mains voltage on the unit they buy, ie,
252Vrms instead of the labelled 220Vrms.

Actually, yes, they can be 'blamed'.

For example, my nephew decided to try the 'wrong' mains setting on a
computer power supply. Why he did it is another story but the PSU is
blown. His fault.


I've lost count of the number of times I have had to repair US made
gear which ppl here have bought on E-bay, then plugged in to 240
without a step down tranny.
A good amp design will just blow a fuse, but not the rectifier diodes.



Btw, 252V is 14.5% above 220V, not 13.7%.

Indeed, but so what?



The question here would be, who represented it would work on what and,
then, what did it end up on?

Huh???

The damn hi-brow makers AND low brow makers SHOULD ensure that users
are made aware of the pitfalls of incorrect mains voltages. But they
all know any mention of anything technical or of any possible negative
outcomes is detrimental to sales figures. They think its better users
burn their gear to bits, with an attitude of utter carelessness about
their customers.

Bullcorn

You are free to believe what you like....

A distributor might, figuring 'it's the manufacturers responsibility'
(more likely ignorance), but no reputable manufacturer ever knowingly
sells equipment that is doomed to fail as the loss of reputation and
warranty service would far exceed any short term gain.

They may claim they don't knowingly sell gear that fails all too
easily, but it fails. ARC is such an old venerable brand, they think
they can let their amps be "conditionally reliable", wheras I would
always look for ways of making my product unconditionally reliable,
like making an amp unconditionally stable.

A few 'fooled you' sales is peanuts compared to the future 'bad
reputation' loss of sales.

Using ARC amps here with 250V mains puts the amps at their most
severely stressed operational condition especially where room temp may
be 35C on a hot day.
I just want ppl to know.

I would prefer they designed their amps so this high stress is
avoidable.

Usually most makers might test their gear during the prototyping
process so that mains voltages of +10% or -10% may be applied
indefinately while retaining 90% of the reliability of the item when
the mains voltage is exactly as specified.

ARC and many other makers in the US and in China etc fail this golden
rule dismally.

Oh really? And just how the hell do you think they work here then?

I see the results of poor amplifier design shortcomings on my work
bench all too often.

So, really, yes, **** happens.



255V is not +-10% of 220V (the rating you stated was on the amp).

When the local shop Duratone Hi-Fi began importing Jolida amplifiers
they found the B+ in their UL amps with EL34 or 6550 *would rise to
+530Vdc and way above the normal 470V and with a big increase in Ia,
and Pda went just above rated limits. So after several cloud-of-smoke
events and angry customers they were forced to modify all the stocks
they imported with a changed arrangement of electrolytic caps which
shorted out. But they also then had to re-bias any all amps to a lower
Ia to avoid a high Pda, and this allowed the B+ to rise even more.

Btw, did it ever occur to you that if there are so many problems in Oz
that maybe there's something 'unusual' about Oz?

There is nothing unusual about Oz. OK, so we have mains which goes up
to 255Vac sometimes.

But if you were here, you might think you were in a state of the Union
because life here is a similar standard to that in the USA.

Ppl here have thought of selling Oz to the USA, but they were told it
more or less already is in USA hands so we don't need to sell it.
The profits of many US owned businesses go back to the US....


As of 2000 your nominal mains voltage is *supposed* to be 230V +10%
-6%.

I can't prove but I suspect the places running a hot 255V (the number
you gave) are occasionally spiking above even that and taking the amps
even further out of spec.

Indeed mains often measures 255Vrms with my Fluke meter.

ARC should take this into account, and adjust their designs to cope
better and keep their amps out of my workshop where i san see them,
inspect them, and then write horrible things about them.

But all ARC owners in Oz ought to know about the horribilities I find.

Then the solutions may be found and offered, so music and happiness
can flow without smoke and repair bills.

I
had the job of fixing two Jolidas after OPT failures, probably caused
by tubes saturating, heating OPT primaries, and then causing shorted
turns.
In one case O opened up tha Jolida 502 OPT to see where/how the short
had occurred, and as stunned my the ****ing lousy quality of the OPT
winding method, so it didn't take much to make the OPTs fail.
The Jolida brand is a is a US-China joint venture, and both the
Chinese and their US exploiters don't give a **** about quality.

While I respect your opinion on how to make OPTs survive a nuclear
blast you are not the world's arbiter of 'quality'.

Nobody is the world's arbiter of anything. I am in the industry of am
making. I do believe in self regulation. This means I will expose
others to scrutiny. It means owners and buyers of amps get a better
deal. And while I talk openly and transparently about all matters
technical I have a 22MB website crammed with ideas.

All makers should welcome my input of constructive criticisms, for
they only stand to gain by making improvements rather than letting
their products become overly complex and too conditional for
reliability.


The correct way to provide for mains voltage selection is as
follows...

There should be TWO mains tranny windings, both meant for 120Vrms, but
so Bmax is 1 Tesla even with 50Hz and 135vrms.
Taps should be placed on both for Common, 100V, 110V, 120V.

Then you can get low loss matches of parallel windings for 100V, 110V,
120V.

Series connection can give 200V, 210V, 220V, 230V, 240V.

The vast majority of the world is standardized in the ranges of
110-120 and 220-230, which is why it's so common to see
"international" transformer primaries rated '115V' and '230V' 50/60Hz.

That means they actually run a little to the high side in the US but
we don't have things blowing up all over the place.

B+ should never rise to more than 95% of the Vdc working voltage
rating of electrocaps even if 1/2 the recommended Ia is used for bias
and if the mains voltage rises 5% above the nominal value of the
country in which the amp is used.

Your own criteria fails in Oz since the 'nominal value' there is
officially given in AS 60038 as 230V and 255V is well over 5% by more
than twice at 10.9%. It doesn't even work for the 240V you *think* is
nominal as 255V is 6.25% over that.

I can't write an industry standard in the time for an email here.

I sure could not propose anything ARC or anyone else would adopt.

Everyone hates being told how to make their gear.


Design engineers in the rest of the world, though, might believe your
government's specifications.

Only a complete fool would build an amp to comply with a government's
spec rather than what is really the case in any country.

In most old radios for the Oz market there were always 3 mains input
selections, 220V, 240V, and 260V.

So where a radio was bought by someone way down a country road with
low mains, he could use the 220V setting. But if he moved to town the
setting was forgotten, but although the city voltage of 240V was and
remains to be so common, the radio rarely would smoke if used with the
wrong setting.

There was no silly attempt to run the 6V6 output tube at high Pda.


So, in Oz, where mains is sometimes 255V, and nominal voltage is
240Vrms,

Your 'nominal' is *not* 240V, it's 230V. Call up Canberra and ask
them.

I have never ever seen 230V here and here is where I live in Canberra.
Sometimes on really cold evenings with high heating power used by all
the mains goes down to 237V.

I cannot alter an established situation.

Those running 240V do so on the grounds it's 'within spec' but it's
*not* nominal and 255V, the number you provided, doesn't meet spec.
It's not 'a lot' out but it is, nevertheless, out.


and where cap rating is +450V, then cap working voltage must
never rise to above
+428Vdc. The best way tfor any maker to avoid problems of exceeding
Elcap V rating is to use caps in series, say rated for 350Vdc each so
that rating is +700vdc and there is never a problem. And the easiest
best way to achieve this is with a voltage doubler type of rectifier.
See my website for many examples.

Nicholson brand soldering irons made in China are widely sold in Oz
and cost about $25 for 80W versions. They are designed to run on
220Vac.
But here and in other parts of Oz we have 255Vac mains and the irons
won't last longer than a month if just plugged in here without a step
down tranny or a series resistor, which I uses, in a metal box under
the bench.

I fused 3 Chinese irons years ago

I guess they didn't plan on them being run 16% over rated.

My guess is that they were made for Chinese condtions, 220Vac, and
sloppy marketeers don't give a ****, and just sell what can be sold.


until I made the step down
resistance box and then when I know there is about 210Vac at the iron,
they run fine for maybe 2 years or more used daily for long periods in
my workshop, with the hot end inside an open jam tin as a guard
agaisnt this falling on the hot iron.
screwed to the bench.
I had used Weller brand mains irons but could never get more than 12
months from them and they cost 3 times as much as the Chinese types.

They probably didn't plan on them being run overrated either.

I returned two failed Weller irons to the Cooper Tools factory in
Albury-Wodonga. They were very keen to inspect irons which had failed.
Probably all soldering irons last years if only used for 1 hour in 6
months, but I often have mine running hot all day, year after year.
Weller sent me two new irons as replacements and tried to tell me the
salt content in water used for making a clay mix used with the iron
wire used in the heating coil had caused the early iron failure, and
despite my resistance box to lower the applied voltage.
I tried telling them to make irons with 12V heating coils of thicker
wire and supply a transformer, but they said that would make it
impossible to compete on price.

The replacements failed and I went to te Chinese product which works
just fine for years if one keeps the applied mains voltage at no more
than 220Vac.

So I can get the Chinese irons to last real good except for the mains
lead from wall socket to iron. Unfortunately the quality of the
ordinary 3 core mains flex has become down graded in just about all
gear compared to previous years. So after 6 months the strands of
copper wire in the mains cables fatigues, arcs, and goes open and
sometimes short circuits and blows switch box circuit breakers. And
all this while oneis using the iron and holding the cable while it
****s itself up.
I have 8 amp circuit breakers for my work bench which limits what I
can use, but I found it necessary because of crap I have to use.
The solution is to wrap a pile of tape around the lead where it enters
the plastic handle of the iron so that the cable bends over a much
wider radius. Its slightly more awkward, but of course a net
improvement.


The ARC uses hi-temp soldering which probably is Rohs complient, ie,
lead free, and of course difficult to solder with irons meant for for
old 35/65 standard solder.
But with the Chinese irons plugged straight into my 250V mains here I
found I could remove the open circuit cathode and screen resistors off
the ARC pcbs, and then solder in replacements using old type solder.

Well, you could get a hotter iron instead of over volting a lower
rated one.

I way well have to get an iron designed to run hotter for the non-lead
soldering.

So far I have not needed to.


The ARC VT200 amp has what appear to be 3 Watt wire wound 100 ohms
series screen resistors. There appear to be old style wire wound.
There are carbon composition 1 ohm x 1W resistors between the 6550
cathodes and the OPT speaker secondary winding which is arranged to
provide 10% local cathode feedback to the two lots of 4 x 6550 on each
side of the PP circuit, ie, in a very similar manner to a Quad-II
amplifier.

To generate enough heat in a 1W x 1 ohm R to make it burst into
flames, one might have to have say 2W of power for some time so the
current must be 1.41 Amps, a huge amount considering the tube curves
indicate 0.5A max with grid bias at 0.0Vdc. To make a 3W x 100 ohm
also fuse open with 6W, then I must be 244 mA, way above the normal
6mA ort working screen current. So obviously when tubes decide to go
beserko, rather high amounts of energy are generated in the tube, and
sometimes it is in the form of very strong RF oscillations which the
"stopper" resistors don't stop. Many makers like ARC and and ALL
others afaik just don't give a **** about the damage shorting output
tubes may cause, and they never would bother to fit active protection
schemes against collateral caused by a failing OP tube.

Protection circuitry is a wonderful thing. My Sony SS 'theater amp'
(had to have something that could decode the TV S/PDIF) has all sorts
of 'smarts' to 'protect' me from doing something stupid except it's
the 'protection' circuitry that's gone insane and keeps shutting down
the amp.

And so often in solid state amps its the fuse which blows last after
several power transistors and a few diodes and driver transistors and
resistors have fused, and the protection circuit did not detect or
react to the presence and effect of a shorted speaker cable at low
volume levels.

I think all SS amp makers have signed a secret Declaration Of
Incompetence, or DOI, and this forbids any one of them to place output
terninals far enough apart to stop strands of speaker cables touching.
I have seen speaker wires owners have used where they have bared the
wires for use with a kitchen knife but have bared far too much, and
never bothered to twist all the strands together. Then they have move
the system around and turned the speakers around thus twisting the two
bared wires together, all without the slightest idea of what may
result. And also forbidden by the secret manufacturers' Agreement Of
Bull****, ie, AOB, is the provision of a circuit costing 50c with two
ICs which detects the presence of a load less than 2 ohms at any level
of operation and which reacts by TURNING THE ****ING AMP OFF but then
displaying a red LED beside a sign which says,
"You have a faulty speaker or cable".

I raise my hat politely to all the fuctards and their shortcomings
because they give me a chance to compete in the market place.....

Never expect to see such a quote in 'Stereophile', a place where
embarrassment is always elegantly sidestepped.


Patrick Turner.