Variac said:
Yeah, that's what I thought too but when I Googled it, it seems that while the quote has been attributed to Twain, it hasn't been able to be verified. One site said that he'd said something a bit similar about Paris.
Hehehe. I'm sure they do.
But then when you folks get a hot spell, like over 90 degrees, y'all start dropping like flies and they send out the Soylent Green trucks to scoop y'all up.
Having spent sub-zero winters in Nevada and Utah, I've found it quite pleasant there every time I've visited.
se
Variac, you're in an odd spot. It's ******* warm on this side of the Bay. Even warmer where Steve is. The lab is already too darn hot just from my little tube amp...
Get a thousand watts of heat going in a room and it will quickly be too warm even in Germany.
Excuse me, I have to go outside and sweat.
Get a thousand watts of heat going in a room and it will quickly be too warm even in Germany.
Excuse me, I have to go outside and sweat.
Hey Bandersnatch
I've seen your method of connecting the driver anodes to the UL taps before. A nice way of getting a more linear feedback than standard Ultralinear. Can you tell us your impressions of this arrangement vs standard Ultralinear?
Did you do any measurements or just (the vital) listening tests? I'm particularly interested on what effect it had on output impedance and total power.
Cheers,
Ian
I've seen your method of connecting the driver anodes to the UL taps before. A nice way of getting a more linear feedback than standard Ultralinear. Can you tell us your impressions of this arrangement vs standard Ultralinear?
Did you do any measurements or just (the vital) listening tests? I'm particularly interested on what effect it had on output impedance and total power.
Cheers,
Ian
Hey-hey!!!,
I don't find that the front end does anything for power( unless it won't swing the voltage ). This one has no troubles with voltage output.
I have not done much measurements. I was hunting a simple circuit for stacked Quad 57's. With the circuit as drawn, there is a damping factor of ~2 with 6BQ7's, 1619's and 9k a-a. It did not quite do the HF well enough.
Sooo, more NFB from what amounts to the same circuit.
Go here:
http://audioroundtable.com/GroupBuild/Projects/
Look at the Merlin amp. The differential cascode front end has a bit of added complexity but sounds fantastic. With 6J6/6H6Pi, HY69's and the 10k 40W Peerless S265Q it makes ~10W with a 300V B+. E-Linear on 30%. At 50% you'll be making 6W( but you can do it with an original,in-the-can OPTx and not have to get a modern rewind/copy ).
The cascode/faux pentode does the phase splitting better than pentodes so far, and offers high output Z for more NFB than a triode would. It rocks quads. You can build this with any multi-grid. I am running the cheaper, 12V, slightly higher gm, HY1269 now. This one likes a little more B+, so a redesign is in the works.
Drop me a line, we can exchange numbers and speak at length. This all bears my copyright.
regards,
Douglas
I don't find that the front end does anything for power( unless it won't swing the voltage ). This one has no troubles with voltage output.
I have not done much measurements. I was hunting a simple circuit for stacked Quad 57's. With the circuit as drawn, there is a damping factor of ~2 with 6BQ7's, 1619's and 9k a-a. It did not quite do the HF well enough.
Sooo, more NFB from what amounts to the same circuit.
Go here:
http://audioroundtable.com/GroupBuild/Projects/
Look at the Merlin amp. The differential cascode front end has a bit of added complexity but sounds fantastic. With 6J6/6H6Pi, HY69's and the 10k 40W Peerless S265Q it makes ~10W with a 300V B+. E-Linear on 30%. At 50% you'll be making 6W( but you can do it with an original,in-the-can OPTx and not have to get a modern rewind/copy ).
The cascode/faux pentode does the phase splitting better than pentodes so far, and offers high output Z for more NFB than a triode would. It rocks quads. You can build this with any multi-grid. I am running the cheaper, 12V, slightly higher gm, HY1269 now. This one likes a little more B+, so a redesign is in the works.
Drop me a line, we can exchange numbers and speak at length. This all bears my copyright.
regards,
Douglas
Miles Prower said:
Thanks to a distortion analyser I have been able to view the distortion life of a PP preamplifier. Symetric start to finish. The second stage allowed a bias per tube. Of course I expected nasty 3rd harmonics. But what I saw was that the disbalance in the output allowed me to gently 'select' a niice distortion makeup (predominant 2nd harmonics) even thought both stages were long-tailed. (6J6 in, E90CC out). The preamp works nice for over 10 years.
Also the French writer in L'Audiophile, Héphaistos, showed such beneficial results in differential pairs by 'wrong biasing'.
My lesson: yes, in theory 2nd Harmonics cancels out, but by tweaking you can dial it back in. This is of course the 'bricolage' approach to building.
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