Audio history
 

Dave Plowman (News) wrote:



** Reading old copies of a magazine called " Wireless World " might
indeed give one the idea that AM radio was all that existed.

You'll need to fish in a bigger pond to find what kicked off the
manufacture of genuine *high fidelity* audio equipment round the world.

It certainly wasn't cinema sound IMHO.



** Oh come on Dave, your opinions have never been humble.

Or the slightest bit relevant.




.... Phil

Audio history
 

In article ,
Phil Allison wrote:
Dave Plowman (News) wrote:



** Reading old copies of a magazine called " Wireless World " might
indeed give one the idea that AM radio was all that existed.

You'll need to fish in a bigger pond to find what kicked off the
manufacture of genuine *high fidelity* audio equipment round the world.

It certainly wasn't cinema sound IMHO.



** Oh come on Dave, your opinions have never been humble.

Or the slightest bit relevant.


Then I take it you are as cloth eared as rude. If you really hold up
optical film tracks as an example of decent sound.

--
*How's my driving? Call 999*

Dave Plowman London SW
To e-mail, change noise into sound.

Audio history
 

On 25/09/2015 6:22 PM, Jim Lesurf wrote:
I've recently been working though Wireless World issues from the 1930s and
1940s, looking for info on the ancient history of audio/hifi. As mentioned
in another posting, doing this at the Museum of Communications in Fife.
They have a fair collection of old mags, abeit with gaps and mainly on
'radio' and related topics.

It occurs to me to ask he

What other magazines from the 1930s-50s period would people expect to
provide reports, reviews, etc, on items like 'radio' and 'radiogram'
chassis or what we'd now think of as 'hifi' or 'audio' home equipment?

The museum do have Practical Wireless, and I think they have ERT. I know
ERT will have some service sheets that are relevant, but beyond that I
don't know enough about the old mags to know if they - or other titles -
would be good places to search though.

Also, anyone here have back issues of 'Hi Fi Sound' from circa 1970? There
may be one or two Armstrong reviews from it I haven't yet tracked down.

Thanks in advance for any help,

Jim


**Jim, I may have something to interest you, but my email to you bounces.


--
Trevor Wilson
www.rageaudio.com.au

---
This email has been checked for viruses by Avast antivirus software.
https://www.avast.com/antivirus

Audio history
 

In article , Trevor Wilson
wrote:

**Jim, I may have something to interest you, but my email to you bounces.

Please change 'noise' to 'web' or 'armstrong'. :-)

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

Audio history
 

I've just put up a new webpage dealing with reviews of Armstrong equipment
during the 'Germanium Era' - i.e. the 400 and 500 ranges. Anyone interested
can find it at

http://www.audiomisc.co.uk/Armstrong...maniumEra.html

I didn't put in the bit about the director from Comet and his 'minders' who
stood either side of him as he sat and told the Armstrong directors what he
expected them to do. Maybe I'll add that in future. But think along the
lines of Arfur Daily, but a bit more intimidating at the time... :-)

Next in line is the silicon era (600 and 700 ranges) then I'll expand on
the 'radio chassis era' once I can track down more reviews, etc.

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

Audio history
 

On 28/09/2015 13:22, Jim Lesurf wrote:
I've just put up a new webpage dealing with reviews of Armstrong equipment
during the 'Germanium Era' - i.e. the 400 and 500 ranges. Anyone interested
can find it at

http://www.audiomisc.co.uk/Armstrong...maniumEra.html

I didn't put in the bit about the director from Comet and his 'minders' who
stood either side of him as he sat and told the Armstrong directors what he
expected them to do. Maybe I'll add that in future. But think along the
lines of Arfur Daily, but a bit more intimidating at the time... :-)

Next in line is the silicon era (600 and 700 ranges) then I'll expand on
the 'radio chassis era' once I can track down more reviews, etc.


I'm intrigued, why do you have a word count at the bottom of the page?


--
Graeme Wall
This account not read, substitute trains for rail.

Audio history
 

In article , Graeme Wall
wrote:

I'm intrigued, why do you have a word count at the bottom of the page?

Habit! :-) I also routinely write for magazines, etc, where the word count
is useful for editors and myself to estimate how well the item fits an
allocated space. And I try to keep a webpage to being of a 'reasonable'
length for someone to read in one go.

In cases like this it helps me decide when a topic might be better split
into a set of pages. Initially, I planned to write a single webpage on the
entire Armstrong review history from 1932 to the 1980s. But quickly
realised it would make sense to split it into 'Eras'. Easier to write as
well as read. And in practice I suspect some people will be interested in
one section rather than another. Currently, I'm planning to split it over 4
webpages. The first and last of which are yet to be written.

As I go, of course, I keep finding items that fit into a section I've done.
So I may eventually expand the pages a bit.

I have the info I need for the 'silicon era'. But am still searching though
potential references for the 'radio chassis' era.

I also add the date to help me keep track of when something was written.
(Sometimes a webpage comes from an item I wrote earlier.)

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

Audio history
 

Jim Lesurf wrote:


I've just put up a new webpage dealing with reviews of Armstrong equipment
during the 'Germanium Era' - i.e. the 400 and 500 ranges. Anyone interested
can find it at

http://www.audiomisc.co.uk/Armstrong...maniumEra.html


** The second review of the 521 amplifier mentions that connecting a Quad Electrostatic, the ESL57, produced low frequency instability with a tone being heard.

This is probably due to the 521 having a feedback loop that connects to the output after passing through a speaker coupling capacitor. While doing this improves the damping factor at low frequencies, the additional phase shift with reactive loads can lead to instability.

In any case, using this speaker with an amp with relatively fragile Germanium output transistors is risky at best - due mainly to the very low impedances seen at sub sonic and also the top the audio band. Quad themselves waited out the mid 60s Germanium era and chose instead more rugged silicon devices plus an output stage that self limited load current to a safe level for their 303.



.... Phil

Audio history
 

Yes. That's why Armstrong at the time weren't keen on anyone using the 521
with an ESL57 and recommended adding a series resistor for anyone who did!

The intended customers for the 400/500's were people who wanted a decent
'value for money' hifi. Customers who didn't expect the best available
regardless of price, but something that would sound good with speakers, etc,
in a similar price bracket.

The assumption was that if someone wanted (and was willing to pay for) ESL's
they'd buy Quad amps because they were specifically designed for the task.
Franchised dealers of the period would be likely to have told customers this.

FWIW I'm sure Armstrong changed the circuit details many times over the period
the 400/500 was on sale. It seems possible that this was why some reviews
thought it was OK when others didn't. Alas, the details are now lost. I
wasn't with the firm at the time, and those who were are now either gone or
can't recall. As with the 600's the printed versions of the diagrams that
were issued didn't track all the changes. Just gave a couple of 'snapshots'
of what was being made at the time.

Personally I wouldn't have used an ESL with a 521 if only because the
AL102s varied so much from one example to the next! Asking for trouble!

Fortunately, most real world users at the time only played music at low
levels into easier loads. It was long before the days of level-compressed
and clipped rock played at deafening levels.

Jim

In article , Phil
Allison wrote:
Jim Lesurf wrote:


I've just put up a new webpage dealing with reviews of Armstrong
equipment during the 'Germanium Era' - i.e. the 400 and 500 ranges.
Anyone interested can find it at

http://www.audiomisc.co.uk/Armstrong...maniumEra.html


** The second review of the 521 amplifier mentions that connecting a
Quad Electrostatic, the ESL57, produced low frequency instability with a
tone being heard.

This is probably due to the 521 having a feedback loop that connects to
the output after passing through a speaker coupling capacitor. While
doing this improves the damping factor at low frequencies, the
additional phase shift with reactive loads can lead to instability.

In any case, using this speaker with an amp with relatively fragile
Germanium output transistors is risky at best - due mainly to the very
low impedances seen at sub sonic and also the top the audio band. Quad
themselves waited out the mid 60s Germanium era and chose instead more
rugged silicon devices plus an output stage that self limited load
current to a safe level for their 303.



... Phil













--
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

Audio history
 

Jim Lesurf wrote:


The assumption was that if someone wanted (and was willing to pay for) ESL's
they'd buy Quad amps because they were specifically designed for the task..



** Actually, the Quad II valve amp was designed at least 4 years *prior* to release of the ESL in 1957. It remained stable with open circuit and low impedance loads, as any good amplifier should. It lacked the power output to damage an ESL but was otherwise designed to drive any 4, 8 or 16 ohm hi-fi speaker system.

Released 10 years after the ESL, the Quad 303 was similarly stable and also short circuit proof. Having a power output of 26 watts into 16 ohms put it on the limit for the ESL. But 45 watts at 8 ohms made it suitable for the vast majority of other speakers available.


Franchised dealers of the period would be likely to have told customers this.


** They likely did, if you visited one with a view to purchase ESLs.

But if you acquired a second hand pair, hooking them up to whatever amp you happen to own is a near certainty.

I personally know one who hooked his pair of ESLs to a Phase Linear 400 and actually got away with it for many weeks.



.... Phil