Triode-wired tetrode like a 436A or 6E5P-E or maybe a planar triode like 7077?
Or since you are playing with phono stuff, how about an 8056?
John
Or since you are playing with phono stuff, how about an 8056?
John
Oh, ya know those beam-deflection tubes like 7360 are pretty linear in the middle of operation.
Tim
The beam deflection tubes might well make the dist. spec, but I don't think they can do 8.5 V rms out from 1 V in with a Mu of 6 or less.
Probably some video amp tube or some big sweep tube in triode. Base 9DX, 9BF or 12something.
Probably some video amp tube or some big sweep tube in triode. Base 9DX, 9BF or 12something.
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C3M triode wired (or is it C3G as you were looking into phono stages, though it is said to be less linear in triode mode).
Solved! 6LE8 in either grid2 drive or grid3 drive(s).
Works good in differential g3 mode too:
http://www.diyaudio.com/forums/tubes-valves/160240-suppresor-grid-used-feedback.html#post2066833
Works good in differential g3 mode too:
http://www.diyaudio.com/forums/tubes-valves/160240-suppresor-grid-used-feedback.html#post2066833
Wow, there's some pretty esoteric guesses!
But the winner is bigwill, with a VERY mundane choice- 12AX7. Despite the knocks, if that tube is run using the lightest possible load, it is impressively linear. Taking it up to the measurement levels up to the 19.8VRMS used in my 5692 (heavy duty 6SN7) tests, the second was still better than -65dB, third and higher below -100dB. That's better than a 6SN7 can do.
The circuit was a single red LED in the cathode and a bipolar current source for a plate load. Test current was 0.8mA. Using my resistor trick to increase LED current had no effect on distortion or gain- the CCS works as advertised.
Show me a DHT with this sort of linearity and kind harmonic distribution and I'll start taking them seriously.
But the winner is bigwill, with a VERY mundane choice- 12AX7. Despite the knocks, if that tube is run using the lightest possible load, it is impressively linear. Taking it up to the measurement levels up to the 19.8VRMS used in my 5692 (heavy duty 6SN7) tests, the second was still better than -65dB, third and higher below -100dB. That's better than a 6SN7 can do.
The circuit was a single red LED in the cathode and a bipolar current source for a plate load. Test current was 0.8mA. Using my resistor trick to increase LED current had no effect on distortion or gain- the CCS works as advertised.
Show me a DHT with this sort of linearity and kind harmonic distribution and I'll start taking them seriously.
EL36 (or EL360, 6CM5, E235L, E236L,...) driven on G2 with Ua~500-600V and Ug2~100-150V and G1 to ground (anode resistor 15-20kOhms, Rk~100-150 Ohms)!
So I'm listening to this phono amp with 12AX7s in two stages, each with 270k anode and 4.7k cathode resistors - if I soup this up to a red led and CCS should it sound better? (I.e. should the distortion fall?).
If so - please provide the exact details of the CCS you measured with please, ideally with a diagram for the ignorant, as someone may want to implement it 🙂
Ahhhh, you're just jealous of bigwill.😀 The "class" hint was supposed to drive people toward DHTs, but that didn't work.
Actually, these results point to use as a voltage amplifier to drive a split load inverter for pp EL84. I'm thinking of rebuilding the RLD to use a 12AX7 to a 6DJ8. A bit more open loop gain will drop the source impedance.
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