GU-50, GM70 and KT88

nina · 29th March 2008, 04:14 PM

Hi,

I wonder how its linearity is at ~400Vdc in triode mode/single ended. Any one has Triode curve of GU-50?

For single ended operation, how is this GU50 tube compare with KT88 and GM70?

Thanks.

ErikdeBest · 29th March 2008, 05:59 PM

Hi

A google search for GU50 triode will reveal good results! I read somewhere that triode connected, the GU50 can take up to 400V (due to the limitation on G2).

I am also curious how it compares soundwise to a KT88... The GM70 will need some more volts on its plate, Brett (member) said it starts singing from 600V onwards.

Erik

nafanja · 30th March 2008, 09:07 AM

This military tube have a good sound for Se and PP, in triod variant.

Have a big time of work.

Good soud with according 6E6P, 6E6P drive tube.

Tweeker · 30th March 2008, 10:11 AM

I have Russian datasheet with triode curve, is too large to attach.

80ma 400V is limit as triode.

I suggest 4Kish load.

Tweeker · 30th March 2008, 10:52 AM

From my running of the curves at 400V 80ma, as you go into high impedances, you start trading off: more 3H, less 2H and less power. Is nice tube.

GM70 needs more volts and has a 60watt filament.

ja2dhc · 30th March 2008, 11:29 AM

GU50 is a Russian version of Telefunken LS50 whose data sheet
can be down-loaded below.

http://www.mif.pg.gda.pl/homepages/f...043/l/LS50.pdf

I purchased a Chinese amp using FU50 Triode Connection
Parallel single ended. FU50 is Chinese version of GU50.
My amp Manufacturer's Web page is below.

http://www.xshn.com/office/cpshow.asp?id=383

The schematics is indicated at the bottom of the Web page.

My amp is introduced in my blog(in Japanese) as below.

http://ja1cty.at.webry.info/200803/article_7.html

nafanja · 30th March 2008, 11:53 AM

I am send You the letter, please look e-mail and my missage

Tweeker · 30th March 2008, 01:52 PM

The Russian tube, while a copy, is not quite identical to the German.

rdf · 30th March 2008, 02:22 PM

There's a thread somewhere here concerning G2 limits of the GU50. The rather contentious consensus was G2 is more power than voltage limited at lower B+. Use a screen resistor, monitor G2 current and voltage, watch the product of the two. I've run it up to 600 VDC and heavy A2 on the bench without issue for about 12 watts SE into a 10k load. FWIW, I very much prefered the harmonic signature of the GU50 into that load over a KT100.

nafanja · 30th March 2008, 08:17 PM

Asd far as i know Russian GU 50 is a copy of Telefunken tube.

But spectral analise may show the difference.
But VA parameters the same.

29th March 2008, 04:14 PM	#1
nina diyAudio Member Join Date: Apr 2005 Location: Earth	GU-50, GM70 and KT88 Hi, I wonder how its linearity is at ~400Vdc in triode mode/single ended. Any one has Triode curve of GU-50? For single ended operation, how is this GU50 tube compare with KT88 and GM70? Thanks.

29th March 2008, 05:59 PM	#2
ErikdeBest diyAudio Member Join Date: Mar 2003 Location: Itoculo	Hi A google search for GU50 triode will reveal good results! I read somewhere that triode connected, the GU50 can take up to 400V (due to the limitation on G2). I am also curious how it compares soundwise to a KT88... The GM70 will need some more volts on its plate, Brett (member) said it starts singing from 600V onwards. Erik __________________ my surname is indeed 'de Best': neither misspelling nor snobbism! Ask SY!

30th March 2008, 09:07 AM	#3
nafanja diyAudio Member Join Date: Mar 2008	Triod variant is fine This military tube have a good sound for Se and PP, in triod variant. Have a big time of work. Good soud with according 6E6P, 6E6P drive tube. __________________ Shippment: $:Europe: 1,2 x (16+2,45 x Weight(kg)) N. Amerika & Asia: 1,2 x (10 +4,9 x Weight(kg))

30th March 2008, 10:11 AM	#4
Tweeker diyAudio Member Join Date: Dec 2004 Location: Cincinnati, Ohio	I have Russian datasheet with triode curve, is too large to attach. 80ma 400V is limit as triode. I suggest 4Kish load. __________________ Be sure your foil hat has a good low impedance ground.

30th March 2008, 10:52 AM	#5
Tweeker diyAudio Member Join Date: Dec 2004 Location: Cincinnati, Ohio	From my running of the curves at 400V 80ma, as you go into high impedances, you start trading off: more 3H, less 2H and less power. Is nice tube. GM70 needs more volts and has a 60watt filament. __________________ Be sure your foil hat has a good low impedance ground.

30th March 2008, 11:29 AM	#6
ja2dhc diyAudio Member Join Date: Dec 2007	GU50 is a Russian version of Telefunken LS50 whose data sheet can be down-loaded below. http://www.mif.pg.gda.pl/homepages/f...043/l/LS50.pdf I purchased a Chinese amp using FU50 Triode Connection Parallel single ended. FU50 is Chinese version of GU50. My amp Manufacturer's Web page is below. http://www.xshn.com/office/cpshow.asp?id=383 The schematics is indicated at the bottom of the Web page. My amp is introduced in my blog(in Japanese) as below. http://ja1cty.at.webry.info/200803/article_7.html

30th March 2008, 11:53 AM	#7
nafanja diyAudio Member Join Date: Mar 2008	For ja2 I am send You the letter, please look e-mail and my missage __________________ Shippment: $:Europe: 1,2 x (16+2,45 x Weight(kg)) N. Amerika & Asia: 1,2 x (10 +4,9 x Weight(kg))

30th March 2008, 01:52 PM	#8
Tweeker diyAudio Member Join Date: Dec 2004 Location: Cincinnati, Ohio	The Russian tube, while a copy, is not quite identical to the German. __________________ Be sure your foil hat has a good low impedance ground.

30th March 2008, 02:22 PM	#9
rdf diyAudio Member Join Date: Jun 2004 Location: big smoke	There's a thread somewhere here concerning G2 limits of the GU50. The rather contentious consensus was G2 is more power than voltage limited at lower B+. Use a screen resistor, monitor G2 current and voltage, watch the product of the two. I've run it up to 600 VDC and heavy A2 on the bench without issue for about 12 watts SE into a 10k load. FWIW, I very much prefered the harmonic signature of the GU50 into that load over a KT100. __________________ Ears aren't microphones.

30th March 2008, 08:17 PM	#10
nafanja diyAudio Member Join Date: Mar 2008	Gu50 Asd far as i know Russian GU 50 is a copy of Telefunken tube. But spectral analise may show the difference. But VA parameters the same. __________________ Shippment: $:Europe: 1,2 x (16+2,45 x Weight(kg)) N. Amerika & Asia: 1,2 x (10 +4,9 x Weight(kg))

Currently Active Users Viewing This Thread: 1 (0 members and 1 guests)

Thread Tools	Search this Thread
Show Printable Version Email this Page	Search this Thread: Advanced Search

Similar Threads
Thread	Thread Starter	Forum	Replies	Last Post
want to do PP-GM70	day	Tubes / Valves	79	10th October 2011 06:30 PM
GM70 sockets?	otto88	Tubes / Valves	41	7th September 2009 09:08 AM
GM70/GM70 parafeed SET?	louischia	Tubes / Valves	10	4th December 2008 03:12 PM
any example of SE designs using GM70?	jarthel	Tubes / Valves	3	31st May 2007 08:10 AM
Another Gm70 amp !!	HFGuy	Tubes / Valves	4	8th July 2005 08:41 PM

New To Site?	Need Help?
Register to Participate Search Privacy Statement Contact Us	Frequently Asked Questions Did you forget your password? Mark Forums Read