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