Has anyone ran Kt-88's in their Mark amp?

[disassembled]

Just curious to see if anyone has run a pair of KT-88's with EL34's or 6L6's in a Mark series amp. Will KT-88's even fit in a mark amp?

I am thinking about getting a quad for my 2:90 when it arrives since the 2:90 and mark series power sections are very similar I figured I'd get more of a response here than with the rack guys.


The first question would be could the PT handle the extra 2.8 amps or so that a quad of KT-88's will draw over a quad of 6L6's? The second question is would it have the same reliability?


Greg

 

[Russ]

Check the physical dimensions of your KT-88's because I am not sure they will even fit on my short chassis. I think it would be absolutely crazy to run them though. Talk about tight and heavy. It would be like swinging a 2x4 at someone's chest or your back when you are playing your amp. I think it would make the amp have a little more bottom from having more headroom if that makes any sense. I would try it if they fit. You might need a specially selected set, a mod, or both to run them though. I saw a Dual Rec that was running 88's on e-bay not too long ago and he had to have a mod to run 6550s/KT-88s. I am assuming the Mark would also need a mod if the tubes would even fit.

 

[disassembled]

It depends on how much current they draw but the plate voltage is right around 460 or so in the Mark IV and 290 which should be fine. I am only talking for the middle pair not the outer pair but I would probably want to run EL34's in the outer sockets to compensate for the extensive lows of the 88's.

If JJ Kt-66s are 2 1/8" in diameter i wonder if they would fit too. When I get my 2:90 I will do some measurements to see how much real estate is in there. Looking at a pic of the 290 with the roof off the only problem I see is maybe the top and bottom covers but the two middle tubes should fit fine otherwise.

I don't think much modding is necessary if you get a cool set. Maybe a bias trim pot for good measure but it might not be needed if they run cool enough.

I bet it would be sweet though especially with a my 212 with EV 12L.

What got me thinking about this is the VHT 2902 which runs 4 KT-88s. It would be cool to try so if i get a few extra bucks I might go for it.

Greg

 

[mxr2000]

interesting would love to know more about findings doing this... 8)