Peter Wieck wrote:

You have my deepest sympathies. This reminds me of some of the items
that have crossed my bench for repair where the owner has a
sentimental reason or some such that makes even the most irrational
approach feasible. One such case, I actually took the few useable
parts out of the item (one output transformer, a choke, front panel
and knobs, cleaned them up and installed them into an entirely
different working chassis (saving the parts from that one, of course),
and returned it to my friend... he thought I had 'worked a miracle'.
He had left the room for a few hours just as his Eico 70 was
experiencing an output tube melt-down... Fortunately the panel breaker
blew before the real-estate was threatened.

I am re-engineering a stereo Woodham CR amp made in the UK.
This nice looking amp has reliably produced clouds of smoke.
It will be totally re-built, using my own circuitry.
It was theraputic to remove all the terribly complex pcb to the rubbish
pile,
and saw a big hole in the case bottom to allow service access,
and fix in a proper top chassis plate.



To this day some 18 years later, he still believes that he has his
original unit, only this time he pays attention to the bias and tube
behavior. I don't charge people to indulge in my hobby, but I warned
him that next time I would.

I have to charge, its my living.

I admire your perseverance, many would have returned the kluge to the
customer and wished them the best of luck. And it does seem to be one
helluvalot of money to spend for a badly conceived kit.

Out of curiosity, do you think such kits are at all feasible in the
real world? Do you think that:

a) better instructions
b) better parts-finishing
c) better diagrams

If all 3 things are improved, yes, the ESL kits could be
equal to a Martin Logan, Quad, et all, and still less than 1/2 the
prices for the
high end names.

Anyone building an ESL kit should salute the High End names for charging
so much, because that high price gives them a chance to compete.


or some permutation/combination of the above could make such a kit
workable for the average Jill or Joe?

Frankly, ppl used to putting a dynamic speaker kit together
with nothing more than a screw driver and bottle of wood glue are in for
a real
shock woth an ESL kit. Its MUCH harder to get right.



You mention that you had to
design-build your own crossovers... They are not complicated, but do
you think this should be "Factory" or at least the bits included?

The "Factory" has not really done any R&D, other than guessing their way
to good sound.
I've done more in a couple of months than they seem to have done.
I finally evolved the crossover R values by trial and measurement after
intial calcs.
It was a surprise to find that the signal applied to the bass panels
has its F2 pole at 160Hz and rolls off at 6dB/octave, and and yet
the acoustic response was essentially flat from 35Hz to 2kHz.
So the bass panels have increasing sensitivity at 6dB/octave if fed with
a
flat signal, so you mustn't do this, because if you did the
response would be an arch, like the Sydney Harbour Bridge,
and the sound would be badly unbalanced with neither bass or upper
treble.


I measure things. I have serious technical expectations. I expect
ruggedness, and simplicity,
and ability to provide louder sound than I ever might use, ie, real
headroom,
sensitivity, and absense of arcing and BS stiction effects.
Even after taking steps to limit the membrane travel, i was able
to turn up the EHT and just watch the membrane move over to be hard
against a stator.
I'd back off the EHT, and it't re-centre, and I could repeat it.
From this I can only think that ALL their bass panels would behave
similarly.
So the amount of EHT is limited to around -2,700V, thus limiting
sensitivity.

If the step up tranny ratio was increased from the existing 1:90 ratio,
then the impedances all reduce; a rise of turn ratio to 1:127 would
halve the impedance.

There is a whole array of things need addressing and balancing.

Peter Walker spent many years developing his line of ESL.


It seems to me from many thousands of miles away that the entire kit
is an afterthought made from factory sweepings...

I wouldn't say the short comings are totally bad.

I'd rather think positive, and hope the kit makers step up the
quality. There IS a market for ESL, somewhat limited by the huge prices
of new ESL speakers.

There is about enough collective experience from the pioneers like Peter
Walker
and his mate Peter Baxandal to allow any keen person to develop decent
ESL panels.

Its all been done before.

Patrick Turner.



But, thank you again for your painstaking description and tale. A
significant example of "doing" over "blathering".

Peter Wieck
Wyncote, PA