Neat circuit, but an expensive tube! See

http://oldradio.qrz.ru/tubes/foreign/01/ECLL800.gif

Not sure how well balanced it is - second half over-driven?. Any
comments?
Cheers,
Roger

PS I've just found a NOS one in a box of old tubes - perhaps Santa
came early this year!
..

"Engineer" wrote in message
.. .
Neat circuit, but an expensive tube! See

http://oldradio.qrz.ru/tubes/foreign/01/ECLL800.gif

Not sure how well balanced it is - second half over-driven?.

No, not over-driven.
Ri of the triode is µ/S = 24K, Ra in this case is 150K.
So in theory amplification is S.[(Ri.Ra)/(Ri+Ra)]= 1.03.

For a practical amp I guess you'll have to play around with
Ra just a little to exactly balance both pethode sections.

Rgds,
Jan.

Any comments?
Cheers,
Roger

PS I've just found a NOS one in a box of old tubes - perhaps Santa
came early this year!
.

"J.Koning" wrote in message
...

"Engineer" wrote in message
.. .
Neat circuit, but an expensive tube! See

http://oldradio.qrz.ru/tubes/foreign/01/ECLL800.gif

Not sure how well balanced it is - second half over-driven?.

No, not over-driven.
Ri of the triode is µ/S = 24K, Ra in this case is 150K.
So in theory amplification is S.[(Ri.Ra)/(Ri+Ra)]= 1.03.

For a practical amp I guess you'll have to play around with
Ra just a little to exactly balance both pethode sections.

Rgds,
Jan.

Any comments?

Yes, there is some performance data at:
http://www.mif.pg.gda.pl/homepages/f.../e/ECLL800.pdf
for a class-B amp on page 1 and for a AB on page 2.
The class AB data exactly refers to your link.
Data is in German but I think it speaks for itself.

Rgds,
Jan.


Cheers,
Roger

PS I've just found a NOS one in a box of old tubes - perhaps Santa
came early this year!
.

"J.Koning" wrote in message
...

"J.Koning" wrote in message
...

"Engineer" wrote in message
.. .
Neat circuit, but an expensive tube! See

http://oldradio.qrz.ru/tubes/foreign/01/ECLL800.gif

Not sure how well balanced it is - second half over-driven?.

No, not over-driven.
Ri of the triode is µ/S = 24K, Ra in this case is 150K.
So in theory amplification is S.[(Ri.Ra)/(Ri+Ra)]= 1.03.

For a practical amp I guess you'll have to play around with
Ra just a little to exactly balance both pethode sections.

Rgds,
Jan.

Any comments?

Yes, there is some performance data at:
http://www.mif.pg.gda.pl/homepages/f.../e/ECLL800.pdf
for a class-B amp on page 1 and for a AB on page 2.
The class AB data exactly refers to your link.
Data is in German but I think it speaks for itself.

Jawohl!

Rgds,
Jan.

Thanks, Jan. I did not notice the low "mu" of the triode My mind was
fixated on a medium gain triode tube!
I had also found the German spec sheet (and printed it for reference,
but "mu" still not noticed.)
Cheers,
Roger

(snip)

In article , "J.Koning"
wrote:

"Engineer" wrote in message
.. .
Neat circuit, but an expensive tube! See

http://oldradio.qrz.ru/tubes/foreign/01/ECLL800.gif

Not sure how well balanced it is - second half over-driven?.

No, not over-driven.
Ri of the triode is µ/S = 24K, Ra in this case is 150K.
So in theory amplification is S.[(Ri.Ra)/(Ri+Ra)]= 1.03.

For a practical amp I guess you'll have to play around with
Ra just a little to exactly balance both pethode sections.

You don't want exact balance of both pentode sections, a slight imbalance
will give the amp just a touch of that sweet SE sound quality.


Regards,

John Byrns


Surf my web pages at, http://users.rcn.com/jbyrns/