OT swapping info

[TweeDLX]

I would like to add a beefier OT to my Mission 5E3 clone. Are there specific issues I need to be aware of, or can I use any old something that I have lying around? Specifically, I have an OT from a Peavey Classic 50 (4 x EL-84 w/8 & 16 ohm taps) that I'm wondering about. I've read where the C-50 OT might want to see a different ohm reading when going from 4 tubes to 2. Correct? Thought I'd ask the experts first...Thanks in advance for your help.

Mike :munch

[TweeDLX]

Um...bump.

:munch

[Wakarusa]

I suppose the first question is what are you trying to achieve? Do you think the PV iron will sounds better than what you have, or you just want to play?

Anyhow, an OT built for 6BQ5/EL84 can be used with 6V6 (the plate to plate impedance you want, voltages and power handling are all close enough to substitute). The problem, as you've already guessed is that the PV iron is marked for 4 tubes and your 5E3 clone only has 2. No real worries, since the OT is really just an impedance matching device -- but halving the power tubes you've double the impedance they present (removed two impedances from 4 in parallel), so the reflected impedance on the OT secondary will be doubled also. What this means in English is that if you use the PV iron in your 5E3, the tap marked 8 ohms really wants a 16 ohm load (the 16 becomes a 32).

[TweeDLX]

I suppose the first question is what are you trying to achieve? Do you think the PV iron will sounds better than what you have, or you just want to play?

Bruce at Mission Amps suggested using an OT rated for higher output to increase my clean headroom. I have the Peavey iron from a cannibalized amp and wondered if it would fit the bill. It seems like it would be better to get one that accepts an 8 ohm load, since that's what I have.

Thanks for the insight!

Mike

[jh45gun]

If you can find a PV OT that has 4/8/and 16 ohm taps for the 4 tube amp then the 4 would read as 8 which is what I had to deal with as my PV OT is for 4 6l6's and I am only using two on my amp build so my 4 becomes the 8 and the 8 becomes the 16 and the 16 32 which of course is useless for most applications but the 4 ohm tap reading then as 8 and the 8 as 16 should work for ya if you can find one of those OT's

[Wakarusa]

... and the 16 32 which of course is useless ...


Aww c'mon. You know you secretly want to try an old Altec PA speaker in there :)