4k vs 5k transformer impedance

[fossilshark]

Hi all, my friend wants a 5w jcm800 so im thinking im going to do an AX84 high octane build.

The closest output transformer I can find has 5k primary impedance instead of 4k @5 watts. Will there be any other issues besides a loss of output power?

[bmccowan]

I think you would be fine with the 5K - but Heyboer makes a 4k to 4/8 ohms I believe. I think I bought one from Carl's custom Amps on ebay.

[tubeswell]

5k reflected load would be better than 4K for a SE EL84 in center-bias Class A.


Zout = Va/(Pa/Va)


250/(12/250) = 5k2

[shooter]

^^^ agree
I would suggest reading Merlin's stuff on DCCF
also expect with big gain feeding small PA you might wind up with the sags like I did

[jeff]

5k reflected load would be better than 4K for a SE EL84 in center-bias Class A.


Zout = Va/(Pa/Va)


250/(12/250) = 5k2

Hello,
Would this mean that a 6V6 running at 360V be better suited to a 10K OT than a 7K?
I built a champ style amp using a 7K but have an extra 10K OT. Worth it/OK to swap out to experiment with the differences?

[jordan86]

I know you did not ask this, but I have built and tweaked an AX 84 SEL. I would highly recommend a conjunctive filter on the output transformer. I have a few threats about it on here.