Looking for a linear triode for lowish B+ CF (6N6P?)

Virtalahde · 27th September 2008, 09:24 PM

People, I have an push-pull ECC88 cathode follower in a piece of equipment with a B+ of 130v (not of my own design) and 11k cathode resistor - 1k+10k with the self-bias point between, working into 2:1 output transformer.

I like its sound but I'd like to try out something which would be a little more linear at the given B+. I won't be chaning the circuit topology, pin order or B+.. Just want to try out a few tubes with their optimal points to find if I could get it accept a little more voltage swing at the inputs.

So far the best thing I've found is the 6N30P, which seems like a real winner at 130v, biased perhaps by a 200R+4k7 resistor for -4v at the grid, if I remember it right.

6N30P's seem bloody expensive, so another cool one would be 6N6P. Not as linear, but seems a little more linear to me and the push-pull configuration would cancel out the distortion.

But just to open up the eyes, I'm asking you gurus - what other tubes I should try?

leadbelly · 28th September 2008, 03:11 AM

IMHO, you're spending your effort on the wrong this. An ECC88 makes a very good cathode follower, and 130V is a pretty decent voltage to work with for that tube. If you spent your effort on replacing the cathode resistors with a CCS, you'd be way ahead of where you are going with just trying other tubes.

Wavebourn · 28th September 2008, 03:12 AM

2xIRF610?

Virtalahde · 28th September 2008, 08:41 AM

Well, I gave some thought to this, too. Might be I just need to try out a CCS. Back to the Gary Pimms site..

andyjevans · 28th September 2008, 10:42 AM

A few choices - 5687, ECC99 as well.

But look at 6S4A and 12B4A - really good sound and you can buy them by the dozen for peanuts. You can then match them, which you need to do since they measure all over the place (especially the 12b4). A stock of these then sets you up for drivers, preamps etc etc. The 6S4A is a particularly useful little tube with its higher gain.

andy

Gordy · 28th September 2008, 11:36 AM

The 6H30 (6N30) really is very linear... and surely not so expensive...
http://www.watfordvalves.com/products.asp?search=6h30

grhughes · 28th September 2008, 04:18 PM

It's not made any more. But don't tell anyone, or there will be a run on the tube. The rabid Koreans and Japanese will buy up all the existing stock and reasonable folk will have to pay through the nose. Ray

27th September 2008, 09:24 PM	#1
Virtalahde diyAudio Member Join Date: Jan 2006 Location: Kuhmoinen, Finland	Looking for a linear triode for lowish B+ CF (6N6P?) People, I have an push-pull ECC88 cathode follower in a piece of equipment with a B+ of 130v (not of my own design) and 11k cathode resistor - 1k+10k with the self-bias point between, working into 2:1 output transformer. I like its sound but I'd like to try out something which would be a little more linear at the given B+. I won't be chaning the circuit topology, pin order or B+.. Just want to try out a few tubes with their optimal points to find if I could get it accept a little more voltage swing at the inputs. So far the best thing I've found is the 6N30P, which seems like a real winner at 130v, biased perhaps by a 200R+4k7 resistor for -4v at the grid, if I remember it right. 6N30P's seem bloody expensive, so another cool one would be 6N6P. Not as linear, but seems a little more linear to me and the push-pull configuration would cancel out the distortion. But just to open up the eyes, I'm asking you gurus - what other tubes I should try?

28th September 2008, 03:11 AM	#2
leadbelly diyAudio Member Join Date: Dec 2002 Location: Calgary, Alberta	IMHO, you're spending your effort on the wrong this. An ECC88 makes a very good cathode follower, and 130V is a pretty decent voltage to work with for that tube. If you spent your effort on replacing the cathode resistors with a CCS, you'd be way ahead of where you are going with just trying other tubes. __________________ Aerodynamics are for people who can't build engines. Enzo Ferrari

28th September 2008, 03:12 AM	#3
Wavebourn diyAudio Member Join Date: Sep 2006 Location: Pleasant Hill, CA	2xIRF610? __________________ The devil is not so terrible as his mathematical model! Wavebourn: We Create Creativity!

28th September 2008, 04:18 PM	#7
grhughes diyAudio Member Join Date: Mar 2005 Location: Cubicle Sweet Cubicle, SW, MO, USA	Yes there is such a tube. It's not made any more. But don't tell anyone, or there will be a run on the tube. The rabid Koreans and Japanese will buy up all the existing stock and reasonable folk will have to pay through the nose. Ray __________________ "The gift of imagination is the gift of the gods imparted to a few for which they receive innumerable kicks in the a$$ their entire life." Le Corbusier (Edward Jenneret)

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28th September 2008, 08:41 AM	#4
Virtalahde diyAudio Member Join Date: Jan 2006 Location: Kuhmoinen, Finland	Well, I gave some thought to this, too. Might be I just need to try out a CCS. Back to the Gary Pimms site..

28th September 2008, 10:42 AM	#5
andyjevans diyAudio Member Join Date: Sep 2003 Location: London	A few choices - 5687, ECC99 as well. But look at 6S4A and 12B4A - really good sound and you can buy them by the dozen for peanuts. You can then match them, which you need to do since they measure all over the place (especially the 12b4). A stock of these then sets you up for drivers, preamps etc etc. The 6S4A is a particularly useful little tube with its higher gain. andy

28th September 2008, 11:36 AM	#6
Gordy diyAudio Member Join Date: Nov 2006	The 6H30 (6N30) really is very linear... and surely not so expensive... http://www.watfordvalves.com/products.asp?search=6h30

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