AudioMisc pages on early J. E. Sugden Class A amps
 

"Phil Allison"

http://www.geocities.com/quad_esl63/...c/power303.jpg

** The output triples inherently limit at 4.5 amps.


** Silicon diodes MR105 & MR106 (along with TR7, the 1.4 volt Vbe
multiplier used for bias setting ) are responsible for this - in
combination, they limit the drive voltage at the input to each triple to
about +/- 2.1 volts, relative to the output line.

MR106 affects the upper triple while MR 105 the lower triple.

The Vbes of TR103 and TR104 plus voltage drops across R120 and R121 &
R124 and R125 add to +/- 2.1 volts when the current flowing into a load is
+/- 4.5 amps, respectively. Current limiting is not sensitive to the phase
angle of the load impedance.

Under shorted or very low impedance load conditions, the power dissipation
in each output device limited to 70 watts, worst case.



........ Phil

AudioMisc pages on early J. E. Sugden Class A amps
 

In article , Phil Allison
scribeth thus

"Phil Allison"

http://www.geocities.com/quad_esl63/...c/power303.jpg

** The output triples inherently limit at 4.5 amps.


** Silicon diodes MR105 & MR106 (along with TR7, the 1.4 volt Vbe
multiplier used for bias setting ) are responsible for this - in
combination, they limit the drive voltage at the input to each triple to
about +/- 2.1 volts, relative to the output line.

MR106 affects the upper triple while MR 105 the lower triple.

The Vbes of TR103 and TR104 plus voltage drops across R120 and R121 &
R124 and R125 add to +/- 2.1 volts when the current flowing into a load is
+/- 4.5 amps, respectively. Current limiting is not sensitive to the phase
angle of the load impedance.

Under shorted or very low impedance load conditions, the power dissipation
in each output device limited to 70 watts, worst case.



....... Phil



Correct me if I'm wrong, and I'm sure you will;!, but the voltage
regulator is involved in the protection?....
--
Tony Sayer

AudioMisc pages on early J. E. Sugden Class A amps
 

In article ,
Phil Allison wrote:
The interest in the Sugden amps mystifies me because they seem to be
so backward.


** A quirky, pommy amp only a quirky pommy could love.

I'd suggest you actually listen to one - especially into a pair of ELS 57s.
It sounds a deal cleaner than a 303 - although obviously slightly down on
power.

--
*Never put off until tomorrow what you can avoid altogether *

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

AudioMisc pages on early J. E. Sugden Class A amps
 

"Dave Plowman (News)"


** A quirky, pommy amp only a quirky pommy could love.

I'd suggest you actually listen to one ....


** Yaaawnnnnnnn - more audiophool DRIVEL !!

I suggest you go drop dead.




........ Phil

AudioMisc pages on early J. E. Sugden Class A amps
 

"tony sayer"


Correct me if I'm wrong, and I'm sure you will;!, but the voltage
regulator is involved in the protection?....



** See what I mean about " insufferable pommies " ??





....... Phil

AudioMisc pages on early J. E. Sugden Class A amps
 

In article , Phil Allison
scribeth thus

"tony sayer"


Correct me if I'm wrong, and I'm sure you will;!, but the voltage
regulator is involved in the protection?....



** See what I mean about " insufferable pommies " ??




** No mate! I'm not quite as insufferable as some Aussie's !!!!


****** the old reg offers some current limiting dontcher tink ore
is that or **** ????? whoops ......................

thats the one;).......


...... Phil





--
Tony Sayer

AudioMisc pages on early J. E. Sugden Class A amps
 

In article ,
Phil Allison wrote:
** A quirky, pommy amp only a quirky pommy could love.

I'd suggest you actually listen to one ....


** Yaaawnnnnnnn - more audiophool DRIVEL !!

I suggest you go drop dead.

So that's your response to a reasonable point?

As it happens I've done just this test which is why I brought it up. And
thought it might be of interest even to you - thinking you may have
changed your attitude to attempts at sensible discussion. So back in the
killfile you go.

--
*Experience is something you don't get until just after you need it *

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

AudioMisc pages on early J. E. Sugden Class A amps
 

In article , Dave Plowman (News)
wrote:
In article , Phil Allison
wrote:
** A quirky, pommy amp only a quirky pommy could love.

I'd suggest you actually listen to one ....


** Yaaawnnnnnnn - more audiophool DRIVEL !!

I suggest you go drop dead.

So that's your response to a reasonable point?

As it happens I've done just this test which is why I brought it up. And
thought it might be of interest even to you - thinking you may have
changed your attitude to attempts at sensible discussion. So back in the
killfile you go.

Which amp did you try?

Slainte,

Jim

--
Electronics http://www.st-and.ac.uk/~www_pa/Scot...o/electron.htm
Audio Misc http://www.audiomisc.co.uk/index.html
Armstrong Audio http://www.audiomisc.co.uk/Armstrong/armstrong.html

AudioMisc pages on early J. E. Sugden Class A amps
 

"Dave Plowman (News)"

** A quirky, pommy amp only a quirky pommy could love.

I'd suggest you actually listen to one ....


** Yaaawnnnnnnn - more audiophool DRIVEL !!

I suggest you go drop dead.

So that's your response to a reasonable point?



** Audiophool drivel is inherently * ANTI * reason.

It is the exact, bloody OPPOSITE of reason .



I do most sincerely suggest YOU go and **** yourself.






........ Phil

AudioMisc pages on early J. E. Sugden Class A amps
 

In article ,
Jim Lesurf wrote:
As it happens I've done just this test which is why I brought it up.
And thought it might be of interest even to you - thinking you may
have changed your attitude to attempts at sensible discussion. So back
in the killfile you go.

Which amp did you try?

All from a failing ;-) memory as it was a long time ago.

A pal was a great ELS fan - but wasn't happy with the 303 as a replacement
for his Quad II amps. And experimented with what I think was a borrowed
A21. And liked the sound. Actually bought the later 25 watt one (A42?)
which he stuck with for a long long time - despite trying the 405 etc.
And demonstrated the various combinations with which I agreed with on his
conclusions.

--
*Windows will never cease *

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