KT77 in place of EL34?

[12AX7]

Isn't it the 77 thats a direct swap for them, and if not what is? 88? I believe it;'s the 77.  Anyways, the question is this...what is the tonal difference between them generally?

[SILVERGUN]

Not sure if you've ever seen this, but I found it to be kinda helpful:
Power Tube Comparison

Jump to 0:39 for KT77 and then 1:21 for EL34

[garyboy]

Yeah you can use the kt77 as a drop in for el34s you'll just hafto rebias also the 77s use alittle less heater current. I tend to like the kt77s more than the el34s. Their mid range isn't quite as compressed and the top end sounds better and the bottom end is tighter. An excellent tube for metaling in my opinion.

[12AX7]

Hmmm....i kinda like that compressed mid tho.  The lack of that sounds sorta like what i hear with 6550's.

[HotBluePlates]

You won't know until you try it and see if you like the sound.

I also didn't like the output tube comparison clip, because I felt the preamp distortion overwhelmed any chance of hearing the differences in how the output tubes might be distorting.

Also note that the amp/speaker anyone uses for a sound clip comparison can skew your impressions... If it's very different from your setup, you may hear very different results. Guitar/amp/speaker/playing style all impact whether you feel a resulting sound from a tube change is a step up or a let down.

[12AX7]

Yeah, I put zero stock in clips anyways. I heard little to no diff like always, yet but the guitar in my hands and i will notice a lot ! A big part is feel too so.....