advances in tube amp design?

[First_octave]

I have posted the david berning OTL amp on audiogon for sell if you guys want to take a look.


http://cls.audiogon.com/cgi-bin/cls.pl?ampstube&1119547860

 

[planet10]

Are those PEARL tube coolers on the output tubes?

dave

 

[First_octave]

Hello

Yes--those are pearl coolers.I have sold the amp now---it was a nice sounding piece.

 

[bear]

<snip>Studying the circuit of lower tube (or follower) of the phasesplitter the junction of the 2x 1M dividers is often shown with a 1M to ground. Strictly one doesn't need this resistor as the 0V return goes through the other resistors. The result is a far better balanced HF response.

The circuit shown is the modified I use so much in 3 stage amps. <snip>
richj

I'm maybe not following the circuit's design... where does the second stage derive its bias voltage from and its drive??

And, I am wondering if the second tube has any gain at DC, and if it matters if it does?

_-_-bear

 

[JZatopa]

So from what I have read of this thread have we learned all we can about the tube? All the new designs out there are just rehashed or slightly modified versions of old designs? I am surprised that there arn't new parts,designs,concepts that could yeild a better amp then what was made 50 years ago.

 

[richwalters]

I am surprised that there arn't new parts,designs,concepts that could yeild a better amp then what was made 50 years ago.

Wer'e dealing with the laws of physics which were sussed out eons ago.... with a slide rule and pencil and a proper understanding which todays people haven't learnt any better.......some cathode materials have improved, but you are right.....the electrodes and the concept are the same.........just as the Otto Motor. Only the brand changes.

richj

 

[rick57]

> the laws of physics were sussed eons ago

Since then we’ve got way better designs with cars, audio source material, video cameras, put man on the moon (at absurd expense), but it seems tube amplifiers are limited . . to just reshuffling the deck . .

 

[smoking-amp]

"but it seems tube amplifiers are limited . . to just reshuffling the deck . ." and rolling tubes around


some more innovations:

can double the output power of your favorite SET triode and use a P-P transformer with no air gap (better frequency response) in SET equivalent mode.
(works even better with a Mosfet in place of the pentode)
http://www.diyaudio.com/forums/showthread.php?postid=632222#post632222

high bandwidth transformers by the foot off a reel, (finally gets it right near the end of the thread) (also, I'm holding back on a fix for the distributed capacitance problem, looking at a patent maybe)
http://www.diyaudio.com/forums/showthread.php?postid=626852#post626852

cosmetic innovation:
http://www.diyaudio.com/forums/showthread.php?postid=633527#post633527

this too:
http://www.diyaudio.com/forums/showthread.php?postid=448813#post448813

well, this one doesn't count:
http://www.diyaudio.com/forums/showthread.php?postid=449149#post449149

but Hawksford error correcting output and active ultralinear are right up there with unity coupling:

http://www.diyaudio.com/forums/showthread.php?s=&threadid=35001&highlight=

http://www.diyaudio.com/forums/showthread.php?postid=590565#post590565

and last but not least, vacuum tube current mirrors:
http://www.diyaudio.com/forums/showthread.php?s=&threadid=40595&highlight=

Don

 

[richwalters]

I don't think car electronics has really improved......recalling vehicle eletronics errors seems to getting evermore louder and it involved millions....so much for reliability. Of course intrumentation has changed.......but human commonsense hasn't........that's got way worse.

A patent search will dig up alot of electronic stuff from the past....so much of todays is copied in a hope to rake in the cash.
Perhaps I am becoming an old fashioned git......but I came from the old school of thought.
The Orient had wide bandwidth ferrites sussed out before the 2nd world war....

richj

 

[405man]

What might also stimulate interest in tube design would be modern tubes. As far as I am aware most output tubes were designed more than 50 years ago with out the aid of any modern design tools. The only example of modern thermionic devices I can think of are CRTs which now use very sophisticated electron optics resulting in much reduced size and greater efficiency and high power RF devices such as TWTs. Perhaps it is time for tube manufacturers to stop producing clones of 50 year old designs and design a modern device for audio use

Stuart

 

[richwalters]

Perhaps it is time for tube manufacturers to stop producing clones of 50 year old designs and design a modern device for audio use

Stuart

Hi there........Swetlana did exactly this with the 6550C (some reason now all's gone quiet with this company unless anyone knows better ).. this tube has been fiddled about so much from the B version that it now has precious metal grids and other fancy things. Despite this, the golden oldie GE 6550A version now obsolete is (obviously unproductive to make) was way supreme in performance compared to the modern counterparts.
In my early days, (1960's) radioactive cathodes were about in tv sets often thought to prolong longevity...these tubes were pushed to their operating limits and often had a short life. I don't think there is a recent new tube on the market with a new designation.
As to your question to design a new audio tube...........I can't see any change........Wer'e stuck with the past.

richj

 

[rick57]

smoking-amp

Holy smoke - You’ve given me a lotta reading!