kt66 in a stock 18watt?

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RockinRocket
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Joined: Sun Nov 20, 2011 5:23 am

kt66 in a stock 18watt?

Post by RockinRocket »

Theoretically if I changed the sockets to octals and stuck some KT66s in my stock 18 watt what would happen? The el84s have around 340 v and the output impedance is correct at 8k. Other than being underpowered what could one expect for volts on the KT66? How would the ez81 feel about this and would the 18 watt transformer be ok with this? Technicaly speaking of course.
10thTx
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Re: kt66 in a stock 18watt?

Post by 10thTx »

The KT66 tubes draw MUCH more current then EL84's and if your power transformer can't handle the current, it will burn up.

With respect, 10thtx
Badside
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Re: kt66 in a stock 18watt?

Post by Badside »

6V6 yes, KT66 no
Amplifiers built:
Marshall 2204 head with some mods
Low-power 2204 (cathode biased 6V6s)
Single-knob dual-6K6GT amps using a Wattkins uPCB
AC30 clone with Plexified preamp section
AX84 Firefly
Stevem
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A

Post by Stevem »

Each 66 needs 1.3 amp for the filament, each 84 only needs .8, so as was posted in short you will likely burn up the PT unless you add a seperate heater sulpply PT.

Sound wise it's likely that you will not have enough drive signal kicking into the 66s and little grit will be added by them, also since to bias them in close to not being too cold the added bias current to do such will cut back on the peak volume that the amp use to have.
A 84 @ around 300 plate volts wants 10 volts of drive signal , while a 66 wants over 30!
You would be better off with running JJ brand 6V6 tubes since they are a bit like a 6L6 !
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RockinRocket
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Re: kt66 in a stock 18watt?

Post by RockinRocket »

Thanks! Exactly the info I was looking for!
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jaysg
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Re: kt66 in a stock 18watt?

Post by jaysg »

RockinRocket wrote:Thanks! Exactly the info I was looking for!
Also there's a KT66 spec about how close they can be in a pair. C to C is about 4.5" I think.
Stevem
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Post by Stevem »

Yes, and some tubes if not mounted in a stand up , or hang down position but in a horizontal position need the tube socket to be clocked a certain way .
This will be stated on the tube spec / data sheet.
When I die, I want to go like my Grandfather did, peacefully in his sleep.
Not screaming like the passengers in his car!😊

Cutting out a man's tongue does not mean he’s a liar, but it does show that you fear the truth he might speak about you!
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Phil_S
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Re: kt66 in a stock 18watt?

Post by Phil_S »

IMO, KT66's move the amp into JTM45 territory. As noted, you'll need other transformers.
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