• WARNING: Tube/Valve amplifiers use potentially LETHAL HIGH VOLTAGES.
    Building, troubleshooting and testing of these amplifiers should only be
    performed by someone who is thoroughly familiar with
    the safety precautions around high voltages.

6n6p or 6P14P-ev for driver

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Well after some experimenting im down to a 6n6p or 6p14p-ev (super Russian el84) with a ccs IXP10M45S running at 20ma for my driver tubes for my projects, a mono diyparadise simple el84 pp for work, and an el34 pp stereo version for home. Both have about the same gain of 20-22.

The question is which one to pick for a grounded cathode setup. What concerns me is that the bias of the 6n6p is suggested at -2v with a b+ of 120v. That only gives a 4v swing tops for the input, and some of my sources are 2vrms. On the other hand the el84 can be biased at -7v all day long. But with a gain of 20 that puts the 4vpp signal at 80v swing which should be good for anything.
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You can easily bias the 6N6P much more than -2V-it is a small power tube after all- unless you are stuck with 20mA current and 120V on the anode. Google "klausmobile" for an easy guide to operating points for both tubes. Personally, I doubt you need to run either tube as hot as 20mA and very few tubes sound best at a lowish anode voltage either. I can vouch for both of these from my own experience as being excellent and the only important consideration might be whether you want to use 2 6P14P requiring more filament current or just one 6N6P.
MOD? Never heard of any piece of electronics that would boost a signal by a fixed db.

Gain of 2 would be 3db. Gain of 4 would be 6db. Gain of 20 would be 26db.

Mu=gain. Or is the mod messing with me?

This would pertain to power gain while you're referring to voltage gain (multiply by two to get correct dB value). Common mistake, I do it every now and then too when writing something quickly in the forum ;)
Sorry, are you running the 6P14P as a triode or a pentode? When you mentioned a gain of 20 I assumed triode. At Va = 120V, Ia =20 mA both tubes will give a bias of a little over 2V if the pentode is triode wired. To get 7V bias with Ia =20mA from a triode wired 6P14P you need Va > 200V.
Sorry the 20ma at 120v was the recommended operating point of the 6n6p.

Im leaning more towards the 6p14p since it looks more linear at 20ma (according to klauz) and can do the larger offset and higher voltage. I might even be able to hook up my preamp without dc blocking caps (output floats at 2.5v) since the tube would never get close to zero even with that big of a dc offset.
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