150V plate output tubes

engels · 9th July 2007, 07:58 PM

I've got a couple of beefy 230:115V transformers which I wanted to put in use. Do you have any suggestions on power tubes which may work good with low voltages?

I've got a couple of SE output transformers with 10K and 5K primaries.

Of course, more output is better, ST octal is better than 9-pin envelope, cheaper is better than expensive etc. I thought about 6G6G output but 1W is not that much.

bigwill · 9th July 2007, 08:22 PM

6c33c / 6c41c

richwalters · 9th July 2007, 08:27 PM

Don't ignore the idea of using secondaries configured as voltage doublers or even triplers, if windings are suitably current rated. Many early amp designs used this technique using cheaper TV components. There was one in particular..name lost..perhaps other members know.

Hint: if there is enough room between bobbin and outer core limb on an E/I core one can often wind a few turns for the heater. Even easier with toroid without centre.
richj

Craig405 · 9th July 2007, 08:36 PM

Make sure they arent auto transformers, if the secondary has a detectable resistance to the primary you are basically tapping straight from the mains without any protection!!

Regards
Craig

Tom Bavis · 9th July 2007, 09:23 PM

6Y6G is cheap enough, and can give a few watts at 160V B+... but I like the idea of the voltage doubler, which will give you a lot more choices, and let you use a 5K transformer (most tubes at 160V will want 2K or so...).

Be sure they are ISOLATION transformers, as already suggested.

Tweeker · 9th July 2007, 09:46 PM

You can also series connect the secondaries for more voltage since you have two.

Also, the two secondaries can be series connected for a 230V winding that can be used as a primary, giving you two 230V secondaries to play with.

astouffer · 9th July 2007, 10:00 PM

The 6K6 looks like another good tube. Same goes for the 6AS7.

Eli Duttman · 9th July 2007, 11:17 PM

Engels,

The nnL6 (not 6L6) group was intended from the start for a "150" V. B+ regime. Tom Bavis is correct about a low impedance O/P trafo being necessary.

I LIKE the voltage doubler idea. That brings "El Cheapo" into play.

Grinding one's own axe is always fun. You said Octal and inexpensive. Build with NOS 12V6s!

Tom Bavis · 10th July 2007, 12:20 AM

The tubes to which Eli refers are: 6W6, 6DG6, 12W6, 12L6, 25L6, 35L6, 50L6, and similar ones in different bases. Not commonly found in "ST" style, though they're quite common and cheap. 25C6G and 50C6G are not common, but there's no demand, so they're quite cheap. They're higher heater voltage versions of 6Y6.

wa2ise · 10th July 2007, 02:50 AM

There's always the 50C5, a 7 pin miniature version of the 50L6, though it won't take B+ over about 160VDC.

At my web page where I built a tube amp in a Sony receiver using such tubes.

9th July 2007, 07:58 PM	#1
engels diyAudio Member Join Date: Jan 2007	150V plate output tubes I've got a couple of beefy 230:115V transformers which I wanted to put in use. Do you have any suggestions on power tubes which may work good with low voltages? I've got a couple of SE output transformers with 10K and 5K primaries. Of course, more output is better, ST octal is better than 9-pin envelope, cheaper is better than expensive etc. I thought about 6G6G output but 1W is not that much.

9th July 2007, 09:46 PM	#6
Tweeker diyAudio Member Join Date: Dec 2004 Location: Cincinnati, Ohio	You can also series connect the secondaries for more voltage since you have two. Also, the two secondaries can be series connected for a 230V winding that can be used as a primary, giving you two 230V secondaries to play with. __________________ Be sure your foil hat has a good low impedance ground.

9th July 2007, 11:17 PM	#8
Eli Duttman diyAudio Member Join Date: Apr 2004 Location: Plainsboro, NJ	Engels, The nnL6 (not 6L6) group was intended from the start for a "150" V. B+ regime. Tom Bavis is correct about a low impedance O/P trafo being necessary. I LIKE the voltage doubler idea. That brings "El Cheapo" into play. Grinding one's own axe is always fun. You said Octal and inexpensive. Build with NOS 12V6s! __________________ Eli D.

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
Sophia Electric™ 300B 2.5V Mesh Plate Tubes	barossi	Tubes / Valves	2	25th October 2004 06:50 AM
Figuring plate resistor values or tubes 101	Original Burnedfingers	Tubes / Valves	15	9th August 2003 11:13 PM

9th July 2007, 08:22 PM	#2
bigwill diyAudio Member Join Date: Dec 2004 Location: UK	6c33c / 6c41c

9th July 2007, 08:27 PM	#3
richwalters diyAudio Member Join Date: Sep 2003 Location: Alps:Tube amp designs over 150W, SMPS guru.	Don't ignore the idea of using secondaries configured as voltage doublers or even triplers, if windings are suitably current rated. Many early amp designs used this technique using cheaper TV components. There was one in particular..name lost..perhaps other members know. Hint: if there is enough room between bobbin and outer core limb on an E/I core one can often wind a few turns for the heater. Even easier with toroid without centre. richj

9th July 2007, 08:36 PM	#4
Craig405 diyAudio Member Join Date: Jul 2005 Location: Sussex	Make sure they arent auto transformers, if the secondary has a detectable resistance to the primary you are basically tapping straight from the mains without any protection!! Regards Craig

9th July 2007, 09:23 PM	#5
Tom Bavis diyAudio Member Join Date: Jun 2002 Location: Macedon NY	6Y6G is cheap enough, and can give a few watts at 160V B+... but I like the idea of the voltage doubler, which will give you a lot more choices, and let you use a 5K transformer (most tubes at 160V will want 2K or so...). Be sure they are ISOLATION transformers, as already suggested.

9th July 2007, 10:00 PM	#7
astouffer diyAudio Member Join Date: Jun 2004 Location: Pittsburgh, crumbling wasteland	The 6K6 looks like another good tube. Same goes for the 6AS7.

10th July 2007, 12:20 AM	#9
Tom Bavis diyAudio Member Join Date: Jun 2002 Location: Macedon NY	The tubes to which Eli refers are: 6W6, 6DG6, 12W6, 12L6, 25L6, 35L6, 50L6, and similar ones in different bases. Not commonly found in "ST" style, though they're quite common and cheap. 25C6G and 50C6G are not common, but there's no demand, so they're quite cheap. They're higher heater voltage versions of 6Y6.

10th July 2007, 02:50 AM	#10
wa2ise diyAudio Member Join Date: Apr 2005 Location: NJ	There's always the 50C5, a 7 pin miniature version of the 50L6, though it won't take B+ over about 160VDC. At my web page where I built a tube amp in a Sony receiver using such tubes.

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

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