On 13/05/2016 08:19, Woody wrote:
"Phil Allison" wrote in message
...
Don Pearce wrote:

Jim Lesurf

Just to let people know I've added some examples to the 'valve
era' page at

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

Jim

Just had a quick skim. Did I read that right? You have to buy and
fit
your own output transformer. If that is really so, I can see why
there
is no overall NFB.



** The EXP48 output stage uses a pair of 6F6 pentodes operating
essentially in class A, so has low distortion without NFB.

However the output impedance is high, providing current drive to the
speaker.
The gain of such a stage follows the speaker's impedance, rising
strongly at bass resonance and also at frequencies above 1kHz due
to voice coil inductance.

With typical speakers of the time, mounted on an open baffle, this
gave the resulting sound an automatic eq that was quite intentional.

Note the lack of any form of tone control.



I remember that from the 60's. In the Music Room the teacher used to
play us records with an old E.A.R. record player with valve amp
feeding what I guess was maybe a 8inch or 10 inch loudspeaker mounted
in the centre of a (quite solid) baffle board about 4ft or so square.
I can still hear it in my minds eye (as it were) to this day - and it
makes me smile.



Used to listen to BBC schools programmes on a similar set up, don't
remember what the receiver was. Well I was only 5!

--
Graeme Wall
This account not read.

In article ,
Graeme Wall wrote:
Used to listen to BBC schools programmes on a similar set up, don't
remember what the receiver was. Well I was only 5!

At my school, it was a Truvox radio jack (crystal set) plugged into the
tape recorder. (Schools broadcasts were never at the correct time for the
appropriate period so always a recording.)

--
*And don't start a sentence with a conjunction *

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

In article , Dave Plowman (News)
scribeth thus
In article ,
Graeme Wall wrote:
Used to listen to BBC schools programmes on a similar set up, don't
remember what the receiver was. Well I was only 5!

At my school, it was a Truvox radio jack (crystal set) plugged into the
tape recorder. (Schools broadcasts were never at the correct time for the
appropriate period so always a recording.)


We used to have a valve Leak amp, can't remember which one now, but we
also had a Troughline tuner. Was a bit peeved that the science master
couldn't explain what one of they was;!...

--
Tony Sayer

In article ,
tony sayer wrote:
In article , Dave Plowman (News)
scribeth thus
In article ,
Graeme Wall wrote:
Used to listen to BBC schools programmes on a similar set up, don't
remember what the receiver was. Well I was only 5!

At my school, it was a Truvox radio jack (crystal set) plugged into the
tape recorder. (Schools broadcasts were never at the correct time for
the appropriate period so always a recording.)


We used to have a valve Leak amp, can't remember which one now, but we
also had a Troughline tuner. Was a bit peeved that the science master
couldn't explain what one of they was;!...

I don't think schools stuff was broadcast on FM in my area when I was a
kid. ;-)

But we did have Leak equipment in the main music room. And a Leak pickup -
mono of course. It was all just dumped on a domestic trolley (dumb waiter)
Gawd knows what H&S would make of that today. Speaker looked to be home
made. Think it was all supplied by a local place.

--
*If you lived in your car, you'd be home by now *

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