Choke tail phase inverter

[mooreamps]

Just wondering if anyone has ever built a choke tail phase inverter.


-g

[octal]

Well, that guy at Boozhound labs has. (Google) I think he also has some sound clips.

[mooreamps]

Ya, I saw that. I'm still thinking of using a pair of 12SJ7 for that purpose, instead of a triode.

-g

[octal]

Wouldn't using pentodes defeat the purpose of the choke tail? I.e. creating a lower impedance drive source / running the PI at a higher current to minimize bias shift/hard grid clipping?

[JoeM]

I've never seen an PI with a choke tail. There was an article in Glass Audio with CCS chip in a Super Reverb. Seems more like a hi-fi type thing though.

[Old Tele man]

...the "tail" resistor functions as a quasi-constant current source, thus serves more as a biasing device.

...substituting a choke for the resistor simply reduces voltage-drop (drastically) and provides a current-sensitive AC-reactance (unlike simple DC-resistance).

[mooreamps]

Wouldn't using pentodes defeat the purpose of the choke tail? I.e. creating a lower impedance drive source / running the PI at a higher current to minimize bias shift/hard grid clipping?

Two thoughts. One, I can run a small signal pentode in triode mode, and have it idle at 8 or 10 mills, which is what I thought was the point. Two,even in triode mode I can still power scale a pentode.


-g