Replacing 6L6s with KT66s?

[Ydna]

Hi. I am going to be aquiring a Fender Dual Showman today, it runs on 6L6s, and I want to know if it would be easy to put KT66s in it. I'm wondering this, because I know that 6L6s have a "kink" in the mids, and have a kind of scooped sound, while KT66s don't, and I've been told that KT66s are very much alike 6L6s. I don't know much about the amp, so I can' say much.

[Mars Hall]

What year is the Fender head? Does it have the bias balance or bias adjustment? Another concern would be the physical size od the head cab, KT66's are quite a bit taller than 6L6's.

Otherwise, they should bias up fine without changing the bias resistor, that is if your head is set up with the bias adjustment verses the balance. Generally speaking Blackface amps have bias adjustment and Silverface have bias balance. There are always exceptions when it comes to Fender stuff, many transitional period amps that will have circuit designs from both eras.

I would try it out as it is for awhile, before opting to change the tube type. Another thing to look for when buying older tube amps, are the see if the filter and bypass caps have been changed or not, if they haven't, you'll want to have those done, especially before you change the tube type.

Most BF and SF Fenders have a mid scoop design, one of Leo's ways of obtaining more clean headroom, so it really is not the tube but the circuit. If you like mid prominent sounds and want a Fender, look for a Tweed or Brownface amp.

[Ydna]

Yea, this is the later version of the Dual Showman. These stopped production in 93, and I think they started in mid 80s. I'm going to just stick with 6L6s. The EQ is push-pull for boost, so I think I can get more mids out of it. Jeez, this thing is gigantic. The 4x12 is 42 inches tall, excluding the wheels. I'm hoping to get some really good tones out of this amp, tide me over until I can get some money together to start a 45/100.

[Mars Hall]

Yea, this is the later version of the Dual Showman. These stopped production in 93, and I think they started in mid 80s.

Is this the red knob model?

[Flames1950]

My concern would be that many Fenders don't have a power tranny rated for a high enough heater current. Not sure about that specific model transformer, but KT66's draw substantially more heater current than the 6L6's which can overheat the transformer........

[Ydna]

It is exactly the same as the red knob model, but has black knobs. And has white snake skin covering. Haha.