EL34 as triode?

[woody]

What would the plate resistance and amplication factor of a
El34 be wired as a triode ?

[kevinkr]

Take a look at the Mullard data sheet, it is all there..

http://www.mif.pg.gda.pl/homepages/f...129/e/EL34.pdf

Ra 910 ohm

mu 10.5

Incidentally quite linear as well.

[woody]

Thanks, I had already looked in my RCA and Sylvania manuals
and it didn't have it. That Mullard sheet was right on the mark.

[ray_moth]

Unfortunately, the info given in data sheets can vary considerably from one to another. I've sometimes had to look at several different manufacturers' sheets for the same tube before I find what I'm looking for.

As said by Kevin, the EL34 is quite linear as a triode, although there has been some debate as to whether the suppressor should be connected to the cathode as advised by Mullard, or to the plate as used by Steve Bench in this circuit. (Actually, Steve is using an E34L but I wouldn't think it makes any difference.)

[Tubes4e4]

Hi Ray_moth,

although there has been some debate as to whether the suppressor should be connected to the cathode as advised by Mullard, or to the plate as used by Steve Bench

What is debatable about it? The curve set is just shifted horizontally for very few percent, likely well within the range of manufacturers tolerances for either connection type, and definitely much less than the difference between any standard EL34 and a JJ/Tesla E34L.

EF91 example from my ETF06 lecture on triode-strapping pentodes.

Tom

[ray_moth]

Hi Tom,

I daresay it is much ado about nothing, just that some people reckon that one way sounds better than the other. I'm not sure that there is a majority for either way.

[Tubes4e4]

Originally posted by ray_moth
Hi Tom,

I daresay it is much ado about nothing, just that some people reckon that one way sounds better than the other. I'm not sure that there is a majority for either way.

Ah, I see. Since the "effect" is within tube tolerances, it just might turn out that for a stereo amp, it very well could turn out the amp as whole would sound best if one power tube´s suppressor is wired to anode, and that of the other channel tube is wired to cathode.

In this regard and by all practical means it would make much more sense and it would be much easier to provide a facility for adjusting the bias voltage to "pull" the operation point within a range (not only two states like g3-strapping) somewhat

Tom