I have just put up two new webpages on the history of Armstrong audio and
'related topics'. You can find them at
http://www.audiomisc.co.uk/Armstrong...s/1979-81.html
and
http://www.audiomisc.co.uk/Armstrong...nale/1982.html

These took a lot longer for me to write than the previous pages and contain
a lot more. I decided to finally spell out in details a lot of the
'features' of the reviews, so the content should give people something to
argue about. Those who believe what they read in reviews may find the
content 'interesting'... :-)

Apologies in advance for any remaining typos, etc. I confess at times my I
got a headache trying to sort out such a long set of info. So I'm sure I've
missed things.

When I have recovered from the effort I now have more info on the much
earlier 'radio chassis' years and will expand that when I can.

Enjoy... 8-]

Jim

--
Please use the address on the audiomisc page if you wish to email me.
Electronics http://www.st-and.ac.uk/~www_pa/Scot...o/electron.htm
Armstrong Audio http://www.audiomisc.co.uk/Armstrong/armstrong.html
Audio Misc http://www.audiomisc.co.uk/index.html

In article , Jim Lesurf
wrote:
I have just put up two new webpages on the history of Armstrong audio
and 'related topics'. You can find them at
http://www.audiomisc.co.uk/Armstrong...s/1979-81.html
and http://www.audiomisc.co.uk/Armstrong...nale/1982.html

I'm now curious that no-one has commented on the contents - particularly of
the 1982 page!

Jim

--
Please use the address on the audiomisc page if you wish to email me.
Electronics http://www.st-and.ac.uk/~www_pa/Scot...o/electron.htm
Armstrong Audio http://www.audiomisc.co.uk/Armstrong/armstrong.html
Audio Misc http://www.audiomisc.co.uk/index.html

On 17/12/2015 18:42, Jim Lesurf wrote:
In article , Jim Lesurf
wrote:
I have just put up two new webpages on the history of Armstrong audio
and 'related topics'. You can find them at
http://www.audiomisc.co.uk/Armstrong...s/1979-81.html
and http://www.audiomisc.co.uk/Armstrong...nale/1982.html

I'm now curious that no-one has commented on the contents - particularly of
the 1982 page!

And Martin Colloms was quite a sensible fellow back in the '70s. :-)

--
Eiron.

In article , Jim Lesurf
scribeth thus
In article , Jim Lesurf
wrote:
I have just put up two new webpages on the history of Armstrong audio
and 'related topics'. You can find them at
http://www.audiomisc.co.uk/Armstrong...s/1979-81.html
and http://www.audiomisc.co.uk/Armstrong...nale/1982.html

I'm now curious that no-one has commented on the contents - particularly of
the 1982 page!

Jim

Haven't got aroundtuit reading it yet Jim!.

--
Tony Sayer

Jim Lesurf wrote:


http://www.audiomisc.co.uk/Armstrong...nale/1982.html

I'm now curious that no-one has commented on the contents - particularly of
the 1982 page!


** You mention speaking with Peter Walker about the "crow bar" circuit in the ESL63. Here is a schem for an early version.

http://www.quadesl.com/schematics/quad63_schematic.gif

The triac used is a T6000B, rated at 16 amps continuous and 150 amp surge for 10mS. Other units use a T2800B, rated at 8 amps with a 100 amp surge rating.

Later ESL63s, from 1989 onwards, used a TIC216D, rated at 6 amps with a 50 amp surge rating.

http://www.euronet.nl/users/temagm/a...ematic_new.jpg

As the crow bar is intended to clip transients that exceed the voltage limit of the panels and only to be used with amplifiers that have electronic current limiting, any of the above are more than adequate.

Large amplifiers with no current limiting are warned against, but if used could fry the smaller triacs or the 1.5 ohm 5W resistor in series. Later models also had a circuit breaker in series.

In any case, the speaker itself was protected, because triacs invariably fail short.


..... Phil

In article , Phil
Allison wrote:

** You mention speaking with Peter Walker about the "crow bar" circuit
in the ESL63. Here is a schem for an early version.

http://www.quadesl.com/schematics/quad63_schematic.gif

The triac used is a T6000B, rated at 16 amps continuous and 150 amp
surge for 10mS. Other units use a T2800B, rated at 8 amps with a 100 amp
surge rating.

Later ESL63s, from 1989 onwards, used a TIC216D, rated at 6 amps with a
50 amp surge rating.

http://www.euronet.nl/users/temagm/a...ematic_new.jpg

As the crow bar is intended to clip transients that exceed the voltage
limit of the panels and only to be used with amplifiers that have
electronic current limiting, any of the above are more than adequate.

Agreed. But the 732 *doesn't* have current limiters and can deliver
sustained RMS currents above the values you gave.

PJW clearly intended the ESL to be used with amps like the 405 which had
current limiters. But I felt they were a PITA for people who had
'difficult' speakers - as the orginal 405 design actually showed very
neatly.

Jim

--
Please use the address on the audiomisc page if you wish to email me.
Electronics http://www.st-and.ac.uk/~www_pa/Scot...o/electron.htm
Armstrong Audio http://www.audiomisc.co.uk/Armstrong/armstrong.html
Audio Misc http://www.audiomisc.co.uk/index.html

In article , Eiron
wrote:
On 17/12/2015 18:42, Jim Lesurf wrote:
In article , Jim Lesurf
wrote:
I have just put up two new webpages on the history of Armstrong audio
and 'related topics'. You can find them at
http://www.audiomisc.co.uk/Armstrong...s/1979-81.html
and http://www.audiomisc.co.uk/Armstrong...nale/1982.html

I'm now curious that no-one has commented on the contents -
particularly of the 1982 page!

And Martin Colloms was quite a sensible fellow back in the '70s. :-)

I keep wondering if someone started putting something into the water that
reviewers drank from the mid 1970s onwards. Was LSD getting easier for some
to obtain, I wonder... ;-

Jim

--
Please use the address on the audiomisc page if you wish to email me.
Electronics http://www.st-and.ac.uk/~www_pa/Scot...o/electron.htm
Armstrong Audio http://www.audiomisc.co.uk/Armstrong/armstrong.html
Audio Misc http://www.audiomisc.co.uk/index.html

In article , Phil
Allison scribeth thus
Jim Lesurf wrote:


http://www.audiomisc.co.uk/Armstrong...nale/1982.html

I'm now curious that no-one has commented on the contents - particularly of
the 1982 page!


** You mention speaking with Peter Walker about the "crow bar" circuit in the
ESL63. Here is a schem for an early version.

http://www.quadesl.com/schematics/quad63_schematic.gif

The triac used is a T6000B, rated at 16 amps continuous and 150 amp surge for
10mS. Other units use a T2800B, rated at 8 amps with a 100 amp surge rating.

Later ESL63s, from 1989 onwards, used a TIC216D, rated at 6 amps with a 50 amp
surge rating.

http://www.euronet.nl/users/temagm/a...ematic_new.jpg

As the crow bar is intended to clip transients that exceed the voltage limit of
the panels and only to be used with amplifiers that have electronic current
limiting, any of the above are more than adequate.

Large amplifiers with no current limiting are warned against, but if used could
fry the smaller triacs or the 1.5 ohm 5W resistor in series. Later models also
had a circuit breaker in series.

In any case, the speaker itself was protected, because triacs invariably fail
short.


.... Phil



Quite the case!. Has anyone had problems with nearby mobile phones
tripping the protection crowbar as mine seem to be very sensitive to
that sort of signal?.

--
Tony Sayer

In article , Jim Lesurf
scribeth thus
In article , Eiron
wrote:
On 17/12/2015 18:42, Jim Lesurf wrote:
In article , Jim Lesurf
wrote:
I have just put up two new webpages on the history of Armstrong audio
and 'related topics'. You can find them at
http://www.audiomisc.co.uk/Armstrong...s/1979-81.html
and http://www.audiomisc.co.uk/Armstrong...nale/1982.html

I'm now curious that no-one has commented on the contents -
particularly of the 1982 page!

And Martin Colloms was quite a sensible fellow back in the '70s. :-)

I keep wondering if someone started putting something into the water that
reviewers drank from the mid 1970s onwards. Was LSD getting easier for some
to obtain, I wonder... ;-

Jim


Yes I used to regard him as one of the better ones then it all started
going downhill, and i stopped buying hi-fi news;!
--
Tony Sayer

In article , tony sayer

wrote:
In any case, the speaker itself was protected, because triacs
invariably fail short.


Quite the case!.

Erm... I have the feeling that people may be reading too much into an
anecdote. The conversation I reported was a casual one we had at a show.
Not a serious analysis we'd have presented at an engineering meeting. I
just thought it amusing as a recollection. :-)

That said, I suspect most users would have concluded that the speaker was
damaged if the actual failure was a welded-short triac that then stopped
the speaker from functioning.

The amp fuses would probably have blown before the output devices.
However...

You have set me wondering, though, what then would happen when/if the amp
went on driving very high steady currents into such a near short. But it
isn't an experiment I'm volunteering to try. I've certainly blown up power
transistors during bench tests when the power was continued after secondary
breadown. The case tended to fly off. Just a matter of how much current,
for how long. ;-

Jim

--
Please use the address on the audiomisc page if you wish to email me.
Electronics http://www.st-and.ac.uk/~www_pa/Scot...o/electron.htm
Armstrong Audio http://www.audiomisc.co.uk/Armstrong/armstrong.html
Audio Misc http://www.audiomisc.co.uk/index.html