25 watt output tube

grungeman91 · 15th September 2010, 04:26 PM

I'm designing my first amplifier for my senior project in electrical engineering. Looking for suggestions for an output tube for 25 watts at the output stage.

leadbelly · 15th September 2010, 04:40 PM

Do you mean a tube with 25W plate dissipation, or a tube that can be used to build a 25W amp? What kind of amp: single ended or push pull, pentode or triode, etc.?

nightanole · 15th September 2010, 06:49 PM

A kt120 with 600v b+ in pentode SE would be the only sane thing i could think of. Lots of stuff if you want 18-25 watts in PP setup though.

Globulator · 15th September 2010, 06:57 PM

I'd use a GU50, then it doesn't really matter how much power you want from it: it will be enough.

Frank Berry · 15th September 2010, 07:11 PM

A pair of 6L6 tubes will easily produce 25 watts in PP AB mode.

kstagger · 15th September 2010, 07:21 PM

EL156 SE as a pentode can swing 24Ws
http://www.mif.pg.gda.pl/homepages/f...28/e/EL156.pdf

I've built a pair of monoblocks using single ended Shuguang EL156s in Ultralinear mode. Very good amplifier.

Wavebourn · 15th September 2010, 07:27 PM

Quote:

Originally Posted by Globulator

I'd use a GU50, then it doesn't really matter how much power you want from it: it will be enough.

Sure. It is still alive even after short dissipation of 100+ watt.

Recently experimenting with monoblock with 4xGU-50 output I made a mistake in bias adjustment. However, it sounded very nice and very loud, but smelled like a burning paint, so I come closer to the amp to sniff what smells, I thought it was some resistor... But I found that anodes were red.

Captn Dave · 15th September 2010, 07:38 PM

Are you actually going to build it? If you are only doing a design, you can use the 6CA7 (EL34) pentode in push pull for an easy 28 watts. The reason I suggest this one is that you will have no problem easily finding datasheets on-line for this popular tube as it is still widely manufactured. Other such options include the KT88 and 6550 pentode with even greater power. Single ended designs are simpler but 25 watts pushes way out on the envelope and I suspect you will struggle to find datasheets on these monsters.

If you are going to build it, then that's another matter.

piano3 · 15th September 2010, 07:45 PM

Is GU-50 good for SE?

Wavebourn · 15th September 2010, 08:05 PM

Quote:

Originally Posted by piano3

Is GU-50 good for SE?

Yes. 450V B+, 4K load, 620 Ohm cathode resistor shunted by capacitor. Needs about 100-120V of input swing. Input transformer may be used to drive by iPod or some other similar source. 100V to 16 Ohm speaker transformer may be good to drive it.

About 40W of idle dissipation, about 100 mA of idle current.

15th September 2010, 04:26 PM	#1
grungeman91 diyAudio Member Join Date: Aug 2010	25 watt output tube I'm designing my first amplifier for my senior project in electrical engineering. Looking for suggestions for an output tube for 25 watts at the output stage.

15th September 2010, 04:40 PM	#2
leadbelly diyAudio Member Join Date: Dec 2002 Location: Calgary, Alberta	Do you mean a tube with 25W plate dissipation, or a tube that can be used to build a 25W amp? What kind of amp: single ended or push pull, pentode or triode, etc.? __________________ Aerodynamics are for people who can't build engines. Enzo Ferrari

15th September 2010, 07:11 PM	#5
Frank Berry diyAudio Member Join Date: Sep 2003 Location: Midland, Michigan	A pair of 6L6 tubes will easily produce 25 watts in PP AB mode. __________________ Frank

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15th September 2010, 06:49 PM	#3
nightanole diyAudio Member Join Date: Feb 2009	A kt120 with 600v b+ in pentode SE would be the only sane thing i could think of. Lots of stuff if you want 18-25 watts in PP setup though.

15th September 2010, 06:57 PM	#4
Globulator diyAudio Member Join Date: Aug 2004 Location: Cambridge, England.	I'd use a GU50, then it doesn't really matter how much power you want from it: it will be enough.

15th September 2010, 07:21 PM	#6
kstagger diyAudio Member Join Date: Dec 2003 Location: Grand Rapids	EL156 SE as a pentode can swing 24Ws http://www.mif.pg.gda.pl/homepages/f...28/e/EL156.pdf I've built a pair of monoblocks using single ended Shuguang EL156s in Ultralinear mode. Very good amplifier.

15th September 2010, 07:38 PM	#8
Captn Dave diyAudio Member Join Date: Jun 2008	Are you actually going to build it? If you are only doing a design, you can use the 6CA7 (EL34) pentode in push pull for an easy 28 watts. The reason I suggest this one is that you will have no problem easily finding datasheets on-line for this popular tube as it is still widely manufactured. Other such options include the KT88 and 6550 pentode with even greater power. Single ended designs are simpler but 25 watts pushes way out on the envelope and I suspect you will struggle to find datasheets on these monsters. If you are going to build it, then that's another matter.

15th September 2010, 07:45 PM	#9
piano3 diyAudio Member Join Date: Aug 2010 Location: London,UK	Is GU-50 good for SE?

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