OT Impedance match

[LooseChange]

I get this mixed up all the time...
A 6V6 pushing an OT with 9K primary, secondary 8 ohms into an 8 ohm speaker.
Switch out the 6V6 to a 6L6.
What secondary (16 ohm or 4 ohm) do I use to best match the 6L6 with the 8ohm speaker?

Thanks!

[tubenit]

I've used a 16 ohm with 5881/6L6 with an Emminence 8 ohm speaker for a number of yrs now & it sounds fine to me. 

Hopefully someone will chime in that actually knows if that's correct.

With respect, Tubenit

[LooseChange]

Your OT has a 9K primary??

Actually the tone is not the issue. The amp sounds great with any impedance choice.

Just looking for the "proper" match. Thanks!!

[tubenit]

Sorry about that.  No, the OT primaries on the two amps I've done this with are 6.6k & 7.6k.

With respect, Tubenit

[Dave]

4 ohms.

If you pulled two tubes out of a twin reverb, you would run an 8 ohm load. Same if you replaced all 4 6l6's w/ 6V6.

You are going the other way. So, 8 ohms for 6V6's becomes 4 ohms for 6L6.

Dave

[jjasilli]

A 2:1 or 1:2 mismatch is considered generally acceptable: e.g.: 4Ω speaker off an 8Ω tap, and vice-versa.  Caveat:  Marshal's are said to be particularly fussy about this.  My SF Princeton was hotrodded with 6L6's, which mismatches the primary OT 1:2; this makes the 8Ω secondary 4Ω.  It drove an 8Ω speaker.  Another 1:2 mismatch on the secondary side.  It worked fine for hours on end, and sounded so good someone insisted on buying it.  I A/B'd 4Ω vs. 8Ω impedances with an impedance matching tranny to convert the now 4Ω tap to 8Ω, to match the speaker.  It sounded good, though a little different, either way.

Ditto to Dave arithmetically.  A tranny performs simple arithmentic.  (How it does this and proper design are too complex for me, but the result is simple).  6L6's have 1/2 the plate impedance of 6V6's.  So, if you halve the impedance on the primary side then you automatically halve the impedance on the secondary side.  The 8Ω tap becomes a 4Ω tap.