The Cleanest Tube?

[open]

Hi everyone,

I'm new to this forum, so goes easy on me, okay? I just bought a THD 30 Watt BiValve ( the one that you can switch the tubes on and it auto baises) I'm trying to find out what are the cleanest tube I can get for it. In other words, ones that don't break up (distort) early or at all. I'm would like to get the cleanest and fullest sound I can get at the highest volume possilbe. Any suggestions? Thanks guys.

[rectifier]

I would suggest the KT-88. It would give you the most clean headroom at the highest power.

[brownnote]

I'd try a good KT-88 too, or a NOS General Electric 6550A or Tung-Sol 6550 for max power.

A Philips / Sylvania 7581A or RCA 6L6GC would be a sound choice for a good clean tone at a little lower volume.

[open]

Thanks a bunch guys. I appreciate the quick response. I did a little research on it yesterday and it does look like the KT88 is probably the best bet. I'm thinking of trying to use them in conjunction with a couple of 12AU7's instead of the 12AX7's I have in there right now. From what I've read, that should get things really clean. However, I have yet to read about someone using an 12AU7 with a KT88. I hope it works out well.

[marshman]

12AU7 is a pretty low-gain pre, so it will probably help if ultimate headroom is your goal, but I would probably install the KTs first, and then start backing down the pre-s a little bit at a time...AX7, then 5751, then AT7, AY7, then AU7, etc... I personally can't imagine using anything less than a 12AT7 as a V1, but I think a lot of tweeds came stock with AY7s, so there you go.

[rectifier]

The 12AY7 is a toneful, excellent sounding preamp tube. I'm using a TungSol 12AY7 in V3 in the tremelo channnel of my 18 watt combo, and I'm getting an excellent warm, punchy clean sound up to 5 on the volume. Past 5, I get a nice beefy overdrive. I've got a Mullard ECC83 in V1 for the normal channel, and use a Whirwind Selector AB box to switch between the channels. I can't seem to put my guitar down these days! I'd bet your THD Bi-Valve would sound great with the 12AY7 and KT-88 combination. I have a Univalve, and when I want headroom, that's what I use. My favorite all around tube in my Univalve is my GEC KT66. The great thing about a BiValve is that you can use 2 different power tubes at the same time. Another tube you might try is a Mullard EL37 for good headroom. They are in the 6L6 family, but can take a lot of voltage and sound great overdriven (and look cool too!).

[PepeJara]

Mullard 12ax7 M1783 version... I am amazed how it has increased the headroom of my 18watt...

[guitar-head]

I recommend using 7027 power tubes. The pin out is the same as a 6L6/6V6. It draws the same amount of heater current as the 6L6. They'll work at the same B+ as 6L6's.

It is designed to be used in low distortion audio amps. Traynor used them in their early YBA-1 bass amp. I have a YBA-1 and can confirm that 7027's do not distort! They sound nice and warm, but they do not distort.

If you want clean try 7027s. JJ and others make them. Here's a link for a pair of Sovtek 7027s.

http://thetubestore.com/sovtek7027.html

Hope that helps.
Don

[open]

Wow! Thanks for the heavy responses guys. This information is helping me immensely. I think I'm going to start out with the KT88's and roll from there. I hope I can return the favor someday. Thanks again.