Single tube, Single ended, 20W, impossible? - Page 3

kstagger · 18th November 2010, 12:02 PM

I was about to mention the EL156 in pentode, but see someone beat me to it.

I built an Shuguang EL156 ULSE amp with 450V on the plate, but never measured the output. It is an easy tube to drive - I used an EF86 in pentode. Plenty of power to run a pair of UREI 813A speakers.

http://www.mif.pg.gda.pl/homepages/f...28/e/EL156.pdf

45 · 04:50 PM

I don't think EL156 with input step-up transformer will work well unless one has a beefy and mighty source. It's not a real solution, it's just shifting the problem from the driver to the source and usually it's just asking for more troubles......
It's that step-up the main problem.
45

mik190 · 19th November 2010, 09:36 AM

Quote:

Originally Posted by coldcathode

So that is an 833A with 2300 Volts on the plate?

WHOA!

Yes, I like this concept - only 1 element, but 2300V - is extremely high. At the moment I try to find something less energetic. But all other single tube variants are around 2W output.

DolganoFF · 19th November 2010, 06:03 PM

What's about this (sadly almost extinct) tube: EL503(EL530)

Plate resistance 7.5K
Transconductance 23 mA/V (!)
Plate dissipation 27W is a little small, but is 20W SE is an absolute necessity for you?

nuvistordave · 2nd April 2012, 05:54 AM

Nearly 20 years ago John Atwater (of one-electron fame) had an SE shoot-out at his home in San Jose. The max power for most of the entries was on the order of 3W...But for the finale I set up my '13 Cubed' SE amplifier. 813's running into custom Doc Hoyer OPT's; 1300V on the plates and 2x SIXTY FIVE WATTS (130 watts total). Of course to spite the narrow minded group; the amplifier was all pentode; drive tubes were EF86's running 6AU5 cathode followers. The amps blew everything into the weeds with their premium OPT's and great circuit design. Later, Svetlana came out with the SV572 triodes. These beauties were good for well over 20 watts; the higher mu ones could easily do over 25 watts. Again, Doc Hoyer came up woth the output iron. I built several of these and sold them to fellow audiophiles.

revintage · 10:16 AM

A Schadeoed EL156 with a depletion mosfet at the input ala MJK would probably do it with acceptable fidelity.

FullRangeMan · 2nd April 2012, 02:09 PM

I surprised no one mention the 805, more rugged than the 211/845 tubes as the 805 plate=125W, and gain is 50 with the same 900V from 211(gain=12) and 845(gain=6), all this for the same sale price.
Howeber these 3 tubes need a driver.

FullRangeMan · 2nd April 2012, 02:23 PM

Quote:

Originally Posted by mik190

Here is the single tube single stage 45W amplifier.

http://spbsound.narod.ru/SPbSound/sc...chematic2.html

I read that some people build it in Russian forums.

Some people in Japane did similar as well as I heard.

I would like to repeat it at less powerfull tubes but did not find the scheme.

WOW, this GM70 amp had a triple secondary output transformer!!... Very impresive, I wonder how it sound??

Any chance did you know the price of this GM70 Integrated?? ("МикроГМка")
http://spbsound.narod.ru/SPbSound/photo/photo7.html
Thanks

Wavebourn · 2nd April 2012, 05:15 PM

Does 10 of 4P1L in parallel count?
Output transformer will be peace of cake, and no lethal voltage required.

Also, B+ easy to stabilize.

v4lve lover · 2nd April 2012, 05:34 PM

YL1260/1350 EL3010 crazy steepness

v4lve

18th November 2010, 04:34 PM	#22
45 diyAudio Member Join Date: Dec 2008 Location: United Kingdom	I don't think EL156 with input step-up transformer will work well unless one has a beefy and mighty source. It's not a real solution, it's just shifting the problem from the driver to the source and usually it's just asking for more troubles...... It's that step-up the main problem. 45 Last edited by 45; 18th November 2010 at 04:50 PM.

2nd April 2012, 10:05 AM	#26
revintage diyAudio Member Join Date: May 2007	A Schadeoed EL156 with a depletion mosfet at the input ala MJK would probably do it with acceptable fidelity. Last edited by revintage; 2nd April 2012 at 10:16 AM.

2nd April 2012, 02:09 PM	#27
FullRangeMan diyAudio Member Join Date: Aug 2009 Location: Brazil	I surprised no one mention the 805, more rugged than the 211/845 tubes as the 805 plate=125W, and gain is 50 with the same 900V from 211(gain=12) and 845(gain=6), all this for the same sale price. Howeber these 3 tubes need a driver. __________________ >Never go to a psychiatrist, adopt a cat or dog from the streets. On the streets pets live only two years average.

2nd April 2012, 05:15 PM	#29
Wavebourn diyAudio Member Join Date: Sep 2006 Location: Pleasant Hill, CA	Does 10 of 4P1L in parallel count? Output transformer will be peace of cake, and no lethal voltage required. Also, B+ easy to stabilize. __________________ If I disappear suddenly, that means I finally created a time machine and pushed wrong button that brought me to Stalin's Russia. In any experiment any result is the result. Even if it is negative.

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18th November 2010, 12:02 PM	#21
kstagger diyAudio Member Join Date: Dec 2003 Location: Grand Rapids	I was about to mention the EL156 in pentode, but see someone beat me to it. I built an Shuguang EL156 ULSE amp with 450V on the plate, but never measured the output. It is an easy tube to drive - I used an EF86 in pentode. Plenty of power to run a pair of UREI 813A speakers. http://www.mif.pg.gda.pl/homepages/f...28/e/EL156.pdf

19th November 2010, 06:03 PM	#24
DolganoFF diyAudio Member Join Date: Jun 2004 Location: Paris	What's about this (sadly almost extinct) tube: EL503(EL530) Plate resistance 7.5K Transconductance 23 mA/V (!) Plate dissipation 27W is a little small, but is 20W SE is an absolute necessity for you?

2nd April 2012, 05:54 AM	#25
nuvistordave diyAudio Member Join Date: Nov 2009 Location: pleasanton ca	Nearly 20 years ago John Atwater (of one-electron fame) had an SE shoot-out at his home in San Jose. The max power for most of the entries was on the order of 3W...But for the finale I set up my '13 Cubed' SE amplifier. 813's running into custom Doc Hoyer OPT's; 1300V on the plates and 2x SIXTY FIVE WATTS (130 watts total). Of course to spite the narrow minded group; the amplifier was all pentode; drive tubes were EF86's running 6AU5 cathode followers. The amps blew everything into the weeds with their premium OPT's and great circuit design. Later, Svetlana came out with the SV572 triodes. These beauties were good for well over 20 watts; the higher mu ones could easily do over 25 watts. Again, Doc Hoyer came up woth the output iron. I built several of these and sold them to fellow audiophiles.

2nd April 2012, 05:34 PM	#30
v4lve lover diyAudio Member Join Date: Aug 2010	YL1260/1350 EL3010 crazy steepness v4lve

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