jtm 45 ot for dumble build?

[FuzzFreak]

I found one of these in my cabinet and really want to put it to good use. its a heyboer and the ct is 3.4k, is it safe to use in place of something like a jcm800 ot?

[ToneMerc]

Sure, build a 50W #183.

TM

[FuzzFreak]

so i can use this ot in any 50 watt config and it will be safe?

[renshen1957]

so i can use this ot in any 50 watt config and it will be safe?

Hi,

Most MI transformers are overpowered as compared to Hi Fi OT. The you would have less bandwidth bass and treble, and more emphasis on midrange. I see no problem.

Best Regards,

Steve

[Harald.Nowak]

I found one of these in my cabinet and really want to put it to good use. its a heyboer and the ct is 3.4k, is it safe to use in place of something like a jcm800 ot?

3.4k is fine for 50 Watts with 400V-450V or so - I used a Hammond 1650K (also 3.4K) in a Bassman/Dumble crossover with 6L6 on anode 430V, yielding around 50 Watts clean. The only thing is (imho) that you may want the sound of a higher OT resistance more - if the OT resistance is comparably light, the load line is going through the 0V grid curve of the 6L6 above the knee (to the right); in this range there is little compression of the tube before grid current flows (grid voltage gets higher than 0V), leading to clamping. If you manage to cut the 0V curve below the knee, you have more compression of the tubes on their own, long before you reach positive grid voltages. What it all boils down to for me is, that I like to drive my Bassman/Dumble thing with a mismatched load (8 Ohm set, 16 Ohm Speaker), leading to something like 6.8k load - sounds a lot better to my ears. Anyways, starting with 3.4K is fine!