low voltage valve use

[punkbass]

hey, i was planning to build a distortion/fuzz pedal which uses a transistor and a valve gain stage.

i have a lot of valves laying around, mainly EC92's E80CC's EABC80's and fewer of the ECC81 ECC82 ECC83 ECC85.

i have the EC92 as the first choice, bacause of its seize and the fact its a single triode, instead of a double, like the others (except fot the EABC80, research that one for your self, hehe), but which ones wil work best on a low voltage (9v)?

[PRR]

> which ones wil work best on a low voltage

All tube suck on low voltage.

But how "good" do you want it to be for a Fuzz?

I suggest build it and see.

[amptramp]

The EC92 is equivalent to a 6AB4 which is half of a 12AT7 and was used as a VHF oscillator and amplifier.  At 100 volts, it has a µ of 60, an Rp of 15,000 ohms and a transconductance of 4 mA/V.  The heater is 6.3V / 0.15 A.  Other ratings are here:

http://www.tubebooks.org/tubedata/HB-3/Receiving-Type_Industrial_Tubes/6664_6AB4.PDF

The EABC80 is the 6T8, a triode with two additional plates driven by the cathode of the triode and a completely separate diode.  The idea was for one of the plates to be an AM detector and the other two diodes to be either a discriminator or ratio detector for FM.  This tube is found in a lot of AM-FM radios.

The E80CC is interesting - it was originally a ruggedized computer tube but there is characterization right down to zero anode volts as shown on page 7 of this:

http://www.mif.pg.gda.pl/homepages/frank/sheets/009/e/E80CC.pdf

where you could get 0.5 mA at 9 volts, sort of like a 12AX7 at higher voltages.  This is a tall 9-pin tube like a 12BH7 and with similar characteristics and it should operate well at low voltages.  It has a µ of 20.

The following are equivalent:

ECC81 = 12AT7
ECC82 = 12AU7
ECC83 = 12AX7
ECC85 = 6AQ8