KT-66 tubes... How do they sound?

[TrueTone500]

I believe they are more 6L6ish. They are not as tight or aggressive as the 6L6s I've used. Higher headroom, more bottom end, smoother high end. The mids are not as pronounced. My experience with them in the SLOs is that they are the more vintage of the 5881s/6L6/Kt66s I've tried. Gold Lions are the only ones I've used based on internet love for them.

To me switching from a 5881 to the KT was like going from the Ruby 12ax7 to an NOS Mullard. Still plenty of gain, more musical and balanced. Much better for cleans and rock, but not as balls out for more modern voicing,

Thanks. My amp is similar to the SLO with exception to some cap values in the tone-stack. I'll just stick with the 6L6's I think. I definitely don't want to dull the mids since it's already a somewhat lower-mid voiced amplifier. It's closest relative would be a Soldano SLO, but with an extended amount of bottom-end.

Soldano SLO T/S

My amps T/S

Didn't love them in my MK50 when I had it. In that amp the 6l6 was my favorite.

I preferred the 6L6's in my MK also. Looking at the schematics, the MK circuit is quite different compared to the RK... Both amplifiers have that bottom-end intensity.

 

[racerevlon]

Marshall Vintage Modern uses KT66 valves. Go play one and decide?

 

[sahlomonic]

Just to add to what Shark Diver has stated - Because they are KT - "Kinkless Tetrode" they do not have any cancellation and all frequencies are there. In some of my amps it can produce the best cleans & lead sounds ~ big & round. In some amps with the extended bottom it will not be as tight as EL34 or even 6L6. In a very tight amp this can be nice because it loosens up the sound a bit. Overall it is just a bigger sound in most amps .... huge actually.

I also agree with rupe about them having more midrange. But the difference's in what David is hearing might be explained by the amp circuit or the other gear being used.

Be aware that with some amps changing tubes can make a huge difference. Other circuits little change is made. What tube the circuit was designed around often is the best sound (taste). Also be aware every tube has it's own sound & property's. Two tubes made on the same day on the same run can react & sound very different. They are like snowflakes ....everyone is different.

Some of my favorite tubes are KT66 & 6CA7 ..... like stated the KT66 has more of a 6L6 sound - but it does have some of the crunch associated with amps designed around EL34. The 6CA7 is more like a EL34 - but has more bottom like a 6L6.

I would not worry about them over smoothing the highend - unless the cut in the mix you get with some amps that have a more brash sound is very important to you.

What amp are you planning on trying them in ?

I've been curious about the KT66 tubes as well. My JCA100H runs 6L6 but after seeing FastRedPonyCar's vid of his with KT66, I agree that it adds a bit more midrange. To my ears the KT66 is somewhat of a blend between 6L6 and EL34 tonally.

Will a 6CA7 bias up like a 6L6 (safe to run in 6L6 amps)?

 

[JTyson]

Just to add to what Shark Diver has stated - Because they are KT - "Kinkless Tetrode" they do not have any cancellation and all frequencies are there. In some of my amps it can produce the best cleans & lead sounds ~ big & round. In some amps with the extended bottom it will not be as tight as EL34 or even 6L6. In a very tight amp this can be nice because it loosens up the sound a bit. Overall it is just a bigger sound in most amps .... huge actually.

I also agree with rupe about them having more midrange. But the difference's in what David is hearing might be explained by the amp circuit or the other gear being used.

Be aware that with some amps changing tubes can make a huge difference. Other circuits little change is made. What tube the circuit was designed around often is the best sound (taste). Also be aware every tube has it's own sound & property's. Two tubes made on the same day on the same run can react & sound very different. They are like snowflakes ....everyone is different.

Some of my favorite tubes are KT66 & 6CA7 ..... like stated the KT66 has more of a 6L6 sound - but it does have some of the crunch associated with amps designed around EL34. The 6CA7 is more like a EL34 - but has more bottom like a 6L6.

I would not worry about them over smoothing the highend - unless the cut in the mix you get with some amps that have a more brash sound is very important to you.

What amp are you planning on trying them in ?

I've been curious about the KT66 tubes as well. My JCA100H runs 6L6 but after seeing FastRedPonyCar's vid of his with KT66, I agree that it adds a bit more midrange. To my ears the KT66 is somewhat of a blend between 6L6 and EL34 tonally.

Will a 6CA7 bias up like a 6L6 (safe to run in 6L6 amps)?

6CA7 is a direct EL34 replacement
If you can run 34's in it, you can run 6CA7's

 

[stephen sawall]

The 6L6 tube family is - 5881, KT66

The EL34- 6CA7, KT77

KT66, 6CA7 & KT77 all kind of sound like a combination of a 6L6 & EL34 - but each have their own personality.