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FDP Forum / Amp Mods, Repairs, and Projects / BDRI // Tung Sol KT66



Jul 14th, 2014 04:21 PM   Edit   Profile   Print Topic   Search Topic

Yo !
The last bit of the below commentary is preventing me from ordering those KT 66's.
Anyone hear know anything about..."if anything is tied to pin one, like in a Fender amp, it will be bad."
The Tung Sol KT66 has all the design specs of a 6L6 and needs to be biased like one, but it does sound like a KT66, and they are fairly reliable. They also have metal bases which are tied to pin one, which means if your amp has bear trap retainers it will short the tube, or if anything is tied to pin one, like in a Fender amp, it will be bad."



Jul 15th, 2014 08:50 AM   Edit   Profile   Print Topic   Search Topic

The linked page from the tubestore site indicates it is likely to be a problem.
It's easy enough to change but I suspect that the Tung Sol KT66 is just their 6L6 in different bottle, so why bother?
Certainly its specs diverge from those of real KT66,

External link



Jul 15th, 2014 11:06 AM   Edit   Profile   Print Topic   Search Topic

Thank you PD. Yes I have been all over the Tube Store looking for answers and have exchanged several e mails. To no avail I'm afraid.
I believe the bear claws are removable.
Reviews of the KT66 by Tungsol report more than just a 6L6. The TS differs only in its current draw, i believe is the correct way of saying it.
Anyway I have a buddy who has ordered a set of the Gold Lions KT66's and the Tungsol's so his amp tech will have the last say, I guess.



Jul 15th, 2014 12:47 PM   Edit   Profile   Print Topic   Search Topic

I'm not a fan of KT66 power tubes unless you are playing heavy overdriven rock. They kind of sound muddy playing clean...which is probably why the 6L6 tube was considered a design improvement decades ago in hi-fi audio.

They eat up more current as well, taxing power transformers and your electric bill.

At the end of the day, I've found that pedals like the Marshall Bluesbreaker will achieve that sound in a more practical way if I ever want to go there.



Jul 15th, 2014 03:42 PM   Edit   Profile   Print Topic   Search Topic

'I believe the bear claws are removable'

OK, that's one way of making it work but it's well into 'there, I fixed it' territory, due to it leaving the tube base shells connected to their control grids, and the tubes liable to work loose from their sockets.
Just need to remove the 1k5 control grid stopper from the pin 1 terminal, in the same way as done on EL34 amps; have a look at some Marshall gut shots.

(This message was last edited by pdf64 at 06:11 PM, Jul 15th, 2014)



Jul 16th, 2014 10:49 AM   Edit   Profile   Print Topic   Search Topic

Thank you GC. I appreciate your perspective.
Overall reviews of KT 66's are glowing. Can't say as I've read a negative thing about them in terms of tone.The Tungsol KT 66 draw is the equivalent of the 6L6.I understand that a KT 66 draws at about 1.2 whereas a 6L6 at about 900.I have heard that with proper biasing the differential may be reduced and become a non problem. Yes I do run a Carl Martin Plexitone on my board.

PD RE tubes left to work themselves out.Apparently the Blues Junior has a brackett which can be put in place instead of the bear claws which does eliminate that worry.The BJ does not use bear claws, apparently.
Please explain further the removal of the IK5 control and what it accomplishes.

Thanks you guys.



Aug 7th, 2014 11:30 AM   Edit   Profile   Print Topic   Search Topic

I do know that there are some "KT66" brands out there that are simply a 6L6GC in a KT66-shaped bottle. Those of course would have the exact same specs as a 6L6...If the Tung-sol people are advertizing their KT66 as having the exact same filament current draw as a 6L6GC...I would assume this might be the case. But other than looking like a KT66 why would you bother? These "fake" KT66 will sound the same as a 6L6GC. Some geniuses in Russia figured out that a 6L6GC will work in any application where a KT66 is called for...and probably better because they draw less current and have a wider frequecy response (with less of a mid hump)....But if you are looking for that vintage sounding low-fi mid-hump of a KT66....they aren't going to deliver.

(This message was last edited by guitarcapo at 01:31 PM, Aug 7th, 2014)



Aug 11th, 2014 08:47 PM   Edit   Profile   Print Topic   Search Topic

The Tung-Sol KT66 is a 1500 ma draw thereby not an exact 6L6GC match at 900 ma. I have used them in my Peavey VK112 with the bear traps removed and screws re-inserted to keep sockets tight to chassis.



Aug 12th, 2014 02:55 AM   Edit   Profile   Print Topic   Search Topic

'The Tung-Sol KT66 is a 1500 ma draw thereby not an exact 6L6GC match at 900 ma'

Why do you think that the TS KT66 (heater) current draw is 1500mA?

Please review the manufacturer's information, linked.

As above, it appears all but identical to that of a 6L6GC, rather than a KT66; to the point of being considered mis-labelled.


(This message was last edited by pdf64 at 04:57 AM, Aug 12th, 2014)

Steve Dallman
Contributing Member

Merrill, Wisconsin

Age is just a number...mine is big
Aug 12th, 2014 03:08 PM   Edit   Profile   Print Topic   Search Topic

I would check the heater voltage with 6L6's and then again with the KT66's. If the heater voltage stays above 6.1 or more, you're probably OK. If it were mine and the voltage dropped at all, I'd either not use the KT's or add an auxillary filament transformer. I've added these to quite a few amps, such as my Bassman 100 when I switched to 6550's. They are pretty inexpensive.



Aug 14th, 2014 08:18 AM   Edit   Profile   Print Topic   Search Topic

There are some tricks you can do if you just want to hear what the amp will sound like with KT66 before going to the trouble of adding an auxiliary transformer. If you remove the preamp tubes on one of the channels and disconnect the pilot light, that might free up some current capacity temporarily in the filament supply.

In a blackface amp, you could just pull the reverb tube, pilot light, oscillator tube and preamp tube for the vibrato channel. That would free up about 1 amp of heater current.

You'd still have impedance issues because your output transformer would be for 6V6 instead of KT66....and then there's also the matter of having enough bias supply on tap to bias those tubes properly.

At the end of the day my personal experience was that all that work wasn't worth the sound you got.
The KT66 is a very raw low-fi sounding tube to my ears. not really in keeping with what blackface fenders are all about. I am kind of intrigued about making a single ended KT66 amp for raw blues.

Like this one

FDP Forum / Amp Mods, Repairs, and Projects / BDRI // Tung Sol KT66

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