KT-88 Tubes in a Mark IV ????

[slayboy3]

Has anyone put 2 KT-88's (with 2 6L6 GC's) in a Mark IV ??

 

[ryjan]

Call Bob at Eurotubes. If it can be done he has done it.

 

[slayboy3]

Bob said that two KT-88's can go in the middle two positions - has anyone ever done this??

 

[rabies]

I've bought some tubes from Bob in the past. Not so bad for the price. He's VERY experimental, esp. by Boogie's rules/standards.

KT88 is what VHT is/was using a lot in the pitbulls, etc.

lots of low-end. I'd like to hear a Mark IV/V with KT88's... brutal.

 

[Dale B.]

I tried it once several years ago. I didn't really like it.

 

[slayboy3]

I tried it once several years ago. I didn't really like it.

What was it about the sound that you did not like?

 

[stephen sawall]

Mesa told me this was a very bad idea..... ask them and they well tell you why. If you want big sounding tubes for IV check out KT66.

 

[slayboy3]

Mesa told me this was a very bad idea..... ask them and they well tell you why. If you want big sounding tubes for IV check out KT66.

What did they tell you??

 

[stephen sawall]

I was thinking about trying KT88 in the amp and called MESA a few times ..... everyone I talked to there told me it was a bad idea. The KT88 that Bob uses is so far off it's normal spec that it is not even acting like a KT88. The rating is very far off the normal range of the amp and is stressing the amp. That he runs amps on the extremes of there range of parameters. Something about this is a way for him to sell off his stock that is not in the normal range for that tube.

This is just what I was told .....I never put KT88 in a Mesa amp.

I should say I have been to Bobs home a few times and have a number of tubes from him .... very nice person. I have played on a number of amps he set up. (tubed and biased) All were running hot. This gives them a lot of punch.

 

[slayboy3]

Bob told me that I could put a pair of KT-88's in the middle two positions and since the bias is fixed - they would be "plug-and-play" i'm going to try it and will let everyone know what happens "fingers crossed".

 

[phyrexia]

Don't do that. Bob does not always know what he's talking about.

 

[rabies]

Don't do that. Bob does not always know what he's talking about.

this may be true. nice sig btw.

 

[slayboy3]

Well I tried it at a low to medium volume - no problems and it sounds good - the bottom is very tight and punchy.

What is the real risk here? I usually play very loud and i'm a little hesitant to really crank this thing up.

 

[rabies]

Well I tried it at a low to medium volume - no problems and it sounds good - the bottom is very tight and punchy.

What is the real risk here? I usually play very loud and i'm a little hesitant to really crank this thing up.

OT or power tube damage. that's about it AFAIK. be careful, i've heard your amp can knock you down with KT88s!

that's why Diezels are cool, the adjustable bias sweep range is wide, thus accommodating a large variety of power tubes...

 

[phyrexia]

KT88s and 6550s draw more heater voltage (or is it current)? and the PT may not be able to handle it under high loads/sustained playing.

 

[rabies]

you're best off getting a mod done if you want to consistently use KT88s (esp. at loud volumes).

 

[stephen sawall]

you're best off getting a mod done if you want to consistently use KT88s (esp. at loud volumes).

What mod ? Adjustable bias ?

 

[rabies]

either adjustable bias or changed the value of the resistor for the non-adjustable bias so it's better-suited for KT88s.