First test drive with the new JJ KT77

novosibir · Post by **novosibir** » Fri Jan 13, 2006 5:28 pm

Today I've got my first quad of the new JJ KT77 and of course I was very curious to hear it and to compare it with JJ's EL34, E34L and with Mullard Xf4's.

At first a huge bias correction was needed and finally I was at the endpoint of my bias pot, to get them down to a max. plate dissipation of 74% - I didn't worry about it, because the distributor has told me, that it wouldn't be a problem to drive them up to a max. dissipation of 100% w/o red plates.

As I've played the tubes in my British Purist (where the Classic channel is very very close to a late '67 plexi circuit), very soon I've noticed, that my expections have been higher than that, what came out of my cabinet 

Compared to the usual JJ EL34 it doesn't have the mid complexity and furryness of this tube, although I can't say, that the KT77 is sounding cold. It's a very dynamic tube, cleaner sounding and it is breaking up later and not as "round", as a EL34 is doing this.

So I'd remembered, what the distributor told me and I've adjusted the bias to about 95% of the max. plate dissipation and played again. Now the sound was "rounder", still a tad warmer and the midrange furryness also was enhanced, but nevertheless it didn't reach the ranges of a JJ EL34 – and after a while of playing I've noticed, that the plates slowly began to get red.

100% of the max. plate dissipation may be possible for 5 minutes with this tube, but never for a whole night show! Adjusted back to 75% the red glow again disappeared, but also the playing feel again was stiffer and the sound less complex and furry.

I really won't say, that this tube is sounding like a 6550, although it's a tube with nearly the same dynamics, but it is sounding warmer, rounder and it also has partially this husky woodiness, which I very like with the JJ EL34 or Mullard. But on the other hand I'd never swap it in my amp instead of these other tubes!

Still some conclusing words about the E34L in comparisation to the KT77: In my ears the E34L is between the both other tubes, but closer to the EL34. The E34L sounds ballsier than the EL34 and even a tad ballsier than the KT77, but isn't sounding as round and warm as a EL34 and isn't as dynamically as the KT77. Both the E34L and the KT77 are lacking a tad midrange complexity in respect to the EL34 – which clearly is my personal favorite among these three tube types.

In my ears the only tube, which still nails the JJ EL34 is the Mullard, but the JJ already is very very close to it.

Larry

Billy Batz · Post by **Billy Batz** » Fri Jan 13, 2006 8:49 pm

Great. Ive been waiting for a review of those. When you say Mullard your talking about the NEw Sensors or real Mullards?

Which 6CA7s have you tried Larry? What were your thoughts on those compared to these other tubes?

novosibir · Post by **novosibir** » Fri Jan 13, 2006 9:05 pm

Billy Batz wrote:Great. Ive been waiting for a review of those. When you say Mullard your talking about the New Sensors or real Mullards?

Of course REAL Mullards. The New Sensor's Mullard only is labelled as a Mullard - but that's already ALL, what both have together. If you'd compare the New Sensor's with real Mullards, after that you'd throw the Russians directly into the carbage

Billy Batz wrote:Which 6CA7s have you tried Larry? What were your thoughts on those compared to these other tubes?

In this case I haven't compared the KT77 with 6CA7's! I have compared it with the JJ EL34, with the JJ E34L and with REAL Mullard Xf4's.

Larry

Billy Batz · Post by **Billy Batz** » Fri Jan 13, 2006 9:16 pm

novosibir wrote:
Billy Batz wrote:Great. Ive been waiting for a review of those. When you say Mullard your talking about the New Sensors or real Mullards?
Of course REAL Mullards. The New Sensor's Mullard only is labelled as a Mullard - but that's already ALL, what both have together. If you'd compare the New Sensor's with real Mullards, after that you'd throw the Russians directly into the carbage

Larry

Yeah. What the hell was I thinking

kt77 · Post by **kt77** » Fri Jan 13, 2006 9:31 pm

in all fairness, you really ought to AB against GEC KT77.....in an amp w/ Partridge OT

I know that Marshall had spec'd them in a couple earlier 100W amps (prob for clean headroom for the SuperBass), but there is prob a reason that idea got abandonded (and I'm sure availability of '77s played a role)

Burman's came stock w/ '77s.....and those amps are HUGE sounding (think Killing Joke).

that's just my opinion...and I'm biased, because I've had nothing but problems w/ JJ tubes (all the ones I had are all dead....two DOA out of the box) and the JJs don't even compare to NOS tonally:roll:

it's kinda like putting EL34s in a Fender Twin and thinking it's gonna sound like a SuperLead

again...opinions

novosibir · Post by **novosibir** » Fri Jan 13, 2006 9:40 pm

kt77 wrote:in all fairness, you really ought to AB against GEC KT77.....in an amp w/ Partridge OT

I still have some orig. GEC KT77 around, but just now none amp with Partridge trannies (Hiwatt)

But today also I hadn't time, to compare the origins with the clones.

Larry

Guest · Post by **Guest** » Sat Jan 14, 2006 12:15 am

Hi, first time posting, but have been seaching for info on these tubes and found this forum. Great review, although I was hoping they would meet or exceed expectations for a GEC KT77. The GEC KT77 is my favorite tube bar none.

Rick

kt77 · Post by **kt77** » Sat Jan 14, 2006 3:51 pm

novosibir wrote:
kt77 wrote:in all fairness, you really ought to AB against GEC KT77.....in an amp w/ Partridge OT
I still have some orig. GEC KT77 around, but just now none amp with Partridge trannies (Hiwatt)

But today also I hadn't time, to compare the origins with the clones.

Larry

nov'
when you get a chance, AB the JJ to the GEC....it would be VERY interesting to hear your review (even in the amp you have)

I may (depending on price) try a pair in my Burman. I'm running Harma E34Ls (HUGE plates!) at the moment.