Bret Ludwig
2007-04-29 08:09:02 UTC
Talk to me, English experts. Tell me all about it.
Discussion:
(too old to reply)
Iain Churches
2007-05-02 20:22:29 UTC
1960s tube amplifier manufacturer based in Scotland.
One of the partners was James Kerr who also
owned a very prestigious hifi shop in Glasgow.
I knew him quite well.
Iain
One of the partners was James Kerr who also
owned a very prestigious hifi shop in Glasgow.
I knew him quite well.
Iain
Bret Ludwig
2007-05-04 00:17:36 UTC
Post by Iain Churches
1960s tube amplifier manufacturer based in Scotland.
One of the partners was James Kerr who also
owned a very prestigious hifi shop in Glasgow.
I knew him quite well.
No relation to Jim Kerr who was pounding Chrissie's hynde, then?1960s tube amplifier manufacturer based in Scotland.
One of the partners was James Kerr who also
owned a very prestigious hifi shop in Glasgow.
I knew him quite well.
What did the Kerr-McCosh amp do that was different?
Patrick Turner
2007-05-04 01:51:30 UTC
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Iain Churches
2007-05-04 05:14:27 UTC
Post by Patrick Turner
Quite a challenge:-))Post by Bret Ludwig
What did the Kerr-McCosh amp do that was different?
Made fuckin bagpipe bands sound real well!!!Post by Iain Churches
1960s tube amplifier manufacturer based in Scotland.
One of the partners was James Kerr who also
owned a very prestigious hifi shop in Glasgow.
I knew him quite well.
No relation to Jim Kerr who was pounding Chrissie's hynde, then?1960s tube amplifier manufacturer based in Scotland.
One of the partners was James Kerr who also
owned a very prestigious hifi shop in Glasgow.
I knew him quite well.
What did the Kerr-McCosh amp do that was different?
Iain
Iain Churches
2007-05-04 06:08:47 UTC
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Bret Ludwig
2007-05-04 22:00:01 UTC
Post by Iain Churches
2. CWA 2/12 Power Amplifier. EL84s PP.
3. CWA 40 Power Amplifier EL34s PP.
The CWA 2/12 was a stereo power amp built as two
"in line" mono channels on the same chassis, with separate
mains transformers. It had an output of 12W at 0.1%
Noise -95dB. Response 25Hz to 30kHz +/- 0.2dB.
The CWA 40 was a monobloc (built on the same chassis
as the CWA 2/12) Output 40W peak continuous. THD=
<0.1% at 38W. Noise -98dB.Response 25Hz to
30kHz +/- 0.2dB.
Both amps were claimed unconditionally stable. They had
huge powder coated transformers in substantial enclosures
with flat lids, typically British, Gardner or Partridge.
The Kerr McCosh amplifiers were very highly regarded
and used in many prof facilities. They were quite a bit more
expensive than Quad. Build quality was IIRC very good
indeed.
Do you have one of their products Bret?
Iain
Unfortunately no. I've never even seen one in the flesh. I was justPost by Bret Ludwig
What did the Kerr-McCosh amp do that was different?
1. DSI stereo control unit. (never seen one)Post by Iain Churches
1960s tube amplifier manufacturer based in Scotland.
One of the partners was James Kerr who also
owned a very prestigious hifi shop in Glasgow.
I knew him quite well.
No relation to Jim Kerr who was pounding Chrissie's hynde, then?1960s tube amplifier manufacturer based in Scotland.
One of the partners was James Kerr who also
owned a very prestigious hifi shop in Glasgow.
I knew him quite well.
What did the Kerr-McCosh amp do that was different?
2. CWA 2/12 Power Amplifier. EL84s PP.
3. CWA 40 Power Amplifier EL34s PP.
The CWA 2/12 was a stereo power amp built as two
"in line" mono channels on the same chassis, with separate
mains transformers. It had an output of 12W at 0.1%
Noise -95dB. Response 25Hz to 30kHz +/- 0.2dB.
The CWA 40 was a monobloc (built on the same chassis
as the CWA 2/12) Output 40W peak continuous. THD=
<0.1% at 38W. Noise -98dB.Response 25Hz to
30kHz +/- 0.2dB.
Both amps were claimed unconditionally stable. They had
huge powder coated transformers in substantial enclosures
with flat lids, typically British, Gardner or Partridge.
The Kerr McCosh amplifiers were very highly regarded
and used in many prof facilities. They were quite a bit more
expensive than Quad. Build quality was IIRC very good
indeed.
Do you have one of their products Bret?
Iain
curious about them. But their reputation is certainly impressive. as
was Radford's. The Quad amp isn't particularly good, although not
particularly bad either. Arguably with its limited output it's
perfectly suited to the Quad electrostats.
Iain Churches
2007-05-08 18:33:14 UTC
Post by Bret Ludwig
curious about them. But their reputation is certainly impressive. as
was Radford's.
Hi Bret,Post by Iain Churches
2. CWA 2/12 Power Amplifier. EL84s PP.
3. CWA 40 Power Amplifier EL34s PP.
The CWA 2/12 was a stereo power amp built as two
"in line" mono channels on the same chassis, with separate
mains transformers. It had an output of 12W at 0.1%
Noise -95dB. Response 25Hz to 30kHz +/- 0.2dB.
The CWA 40 was a monobloc (built on the same chassis
as the CWA 2/12) Output 40W peak continuous. THD=
<0.1% at 38W. Noise -98dB.Response 25Hz to
30kHz +/- 0.2dB.
Both amps were claimed unconditionally stable. They had
huge powder coated transformers in substantial enclosures
with flat lids, typically British, Gardner or Partridge.
The Kerr McCosh amplifiers were very highly regarded
and used in many prof facilities. They were quite a bit more
expensive than Quad. Build quality was IIRC very good
indeed.
Do you have one of their products Bret?
Iain
Unfortunately no. I've never even seen one in the flesh. I was justPost by Bret Ludwig
What did the Kerr-McCosh amp do that was different?
1. DSI stereo control unit. (never seen one)Post by Iain Churches
1960s tube amplifier manufacturer based in Scotland.
One of the partners was James Kerr who also
owned a very prestigious hifi shop in Glasgow.
I knew him quite well.
No relation to Jim Kerr who was pounding Chrissie's hynde, then?1960s tube amplifier manufacturer based in Scotland.
One of the partners was James Kerr who also
owned a very prestigious hifi shop in Glasgow.
I knew him quite well.
What did the Kerr-McCosh amp do that was different?
2. CWA 2/12 Power Amplifier. EL84s PP.
3. CWA 40 Power Amplifier EL34s PP.
The CWA 2/12 was a stereo power amp built as two
"in line" mono channels on the same chassis, with separate
mains transformers. It had an output of 12W at 0.1%
Noise -95dB. Response 25Hz to 30kHz +/- 0.2dB.
The CWA 40 was a monobloc (built on the same chassis
as the CWA 2/12) Output 40W peak continuous. THD=
<0.1% at 38W. Noise -98dB.Response 25Hz to
30kHz +/- 0.2dB.
Both amps were claimed unconditionally stable. They had
huge powder coated transformers in substantial enclosures
with flat lids, typically British, Gardner or Partridge.
The Kerr McCosh amplifiers were very highly regarded
and used in many prof facilities. They were quite a bit more
expensive than Quad. Build quality was IIRC very good
indeed.
Do you have one of their products Bret?
Iain
curious about them. But their reputation is certainly impressive. as
was Radford's.
Along with the large numbers of medium-priced, medium performance
tube amps there were, in the UK at least, quite a number of firms building
good amplifiers to a high standard. Both Radford and Kerr McCosh were
good examples, along with Shirley Laboratories and several others.
The object of the exercise was to build an amplifier as well as possible
with the current technology. The opinions of the bean-counters were
not important, as such an amplifier would sell on its performance
alone.I an sure the situation was the same in the US.
This was at a time when the demarcation between high-end/semi pro
and professional was less defined than it is now. Arthur Radford was
actually a builder of precision audio test instruments and so the
transition to high performance audio amplifiers was not a quantum
leap.
A Radford LODI (Low distortion oscillator) produces a sine wave
with THD better than 0.001% see:
Loading Image...
and also
http://www.kolumbus.fi/iain.churches/ThermionicThoughts/TestBenchFunctionGenerators.html
Many are still in use in studios and prof installations. They rarely come
on the market, and when they do they are bought by the Japanese
at very inflated prices.
The same goes for Kerr-McCosh. Jim Kerr was a very capable
engineer with a studio background. He had a thriving retail business
with clients who were prepared to pay for quality. He built his
amplifiers to fit this market niche, which even in this day of "plug
and play" still seems to exist. There are still people who are
willing to dig deep into their pockets for a quality item, especially
something tailored to fit their specific requirements.
The same applied to Wayne-Kerr (it's that name again)
test equipment.
Hmm. Easy to say in hindsight:-) When the Quad II Mk II
appeared in 1952 is was a pretty remarkable amplifier
which remained in production for almost 20 years, with
nearly 140,000 units built. That's a pretty successful
amp in my book:-))
Arguably with its limited output it's
Agreed
Iain
campbellcw@aol.com
2018-04-02 14:28:50 UTC
James Kerr built amplifiers which could stand conditions abroad and were much in use by colonial expats - hence retaining the Valve! The Retail business was run by his partner Ted MacCosh (hence the name)and included Record sales (under Tony Austin) and upmarket Hifi (run by Tom Simmons) with closed circuit sound systems being installed in many landed estates' "Big houses" installed by Hugh Coulter (sometime Glasgow taxi-driver!)