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Guru amp designer Bruce Egnater discusses his highly acclaimed designs!
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KT66 in a Tweaker 40?

Thu, Nov 01, 2012 10:33pm

Just got the Tweaker 40 head a couple days ago, so far I'm loving the sound, but I'd like to experiment with some different tube types. Specifically someone mentioned using KT66s but I haven't been able to confirm whether or not this is safe (i.e. whether this will fry the amp).

I've got a set of JJ KT66s lying around that I'd like to put to good use. Anyone know if this is feasible and if so what I should set the bias at (using the internal bias points). I'm already pretty well acquainted with biasing the amp (popped a set of EL34s in there earlier just for kicks; sounded great dirty, but I didn't like how it affected the clean sound), I just want to check what I should set the bias for.

Re: KT66 in a Tweaker 40?

Sun, Nov 11, 2012 10:23pm

Not a good idea to use KT66 in this amp as they draw more heater current than 6L6s. One 6L6 - 0.9 amps heater current, one KT66 - 1.3 amps heater current, so that's nearly 0.8 amp more current from the power transformer with two KT66 tubes installed. Considering the transformer issues with Egnater, you'll be fortunate if the amp holds up with the 6L6s.


Re: KT66 in a Tweaker 40?

Sat, Mar 09, 2013 9:41am

So you can put EL-34's in the tweaker 40? what should the mA be for bias? what about 6v6?

Re: KT66 in a Tweaker 40?

Mon, Mar 11, 2013 9:26pm

I wouldn't put el34s in the tweeter, higher filament current than the kt66 as noted above.

El34-1.5 current required
Kt66-1.3. " "

You need to review schemo filiment supply pt to see if there is enough head space. Good luck in getting any tech support from Egnater.

Re: KT66 in a Tweaker 40?

Sat, Mar 16, 2013 6:55am

You can put EL34 in the tweaker 40 here is the bias document from Bruce

Re: KT66 in a Tweaker 40?

Sat, Apr 06, 2019 3:49am

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