Steve- a tube question or two...

Steve, a lot of folks who aren't too experienced with tubes might be curious about some of the sonic characteristics of certain tube types - maybe you could give us some general thoughts on some common amp tubes (EL34, KT-88 and 6550 are generally used in the equipment us beginners muight run into) and what kinda sonic things happen when you choose a particular amp/tube combo. Same goes for preamp type tube - 12AX7's, 6DJ8/6922/7308 family - maybe this question is kinda vague, but I bet your thoughts might help us make more informed choices when we solid state folks take the plunge into glowing bottles...

 

I've asked Steve H. these toob questions several times.

The vintage amps out there used all three types of output tubes: 6L6GC (KT-66 as well), EL-34's, 6550 (KT-88 as well).

Other than the big transmitting tubes made popular by Japanese SET designers, that is pretty much it in the way of output tubes.

The El-34's for old Marantz should be Mullards, as they invented the tube. Seimens makes a great modern version.

6L6GC's should be GE's for McIntosh, RCA Black Plate for Fender guitar amps. Steve doesn't like KT-66's or EL-37's except for Marshall Amps.

6550's for Mac 60's should be Tung-Sol's. They invented the tube. The British KT-88 can SOMETIMES be used in place of the 6550, and vica versa. Genelex KT-88's aka GEC are the ones to use.

Input tubes.

Steve said that the Telefunken 12AX7 is the one and only tube he likes. NOT so for 12AU7's. They should be Amperex Bugle Boys or Mullards.

Steve likes a certain 6DJ8 tube, but I can't remember which one. Sorry.

But, off the top of my head, how did I do?

 

Neat.

Totally boggles my mind, but I guess if I was into it, I would know all the correct versions of tubes to use as well.

I used to think that if one had tube gear, it didn't even matter what brand of tubes were used.

 

I'm following this thread closely, because I have a pair of McIntosh MC30s and I'm just getting into tube rolling.

So two nights ago I realized I had a quad of Telefunken ECC/83/12AX7s that I wasn't using, so I put them in the MC30s -- I replaced some new Sylvanias my repair guy had installed.

My Macs basically became new amps. The air, the timbre, the presence, the "there-ness" of the music and vocals increased exponentially. I'm still a little freaked out over it.

I cannot wait to get my hands on a quad of GE 6L6GCs and some of those Mullard 12AU7s. I am sure those tubes will be worth the money.

 

Yes, Indeed.

Steve has stated to us several times that the McIntosh 30 is his favorite of all the vintage amps. It has a "sound" all its own.

His tube rolling ended when he got his cheap GE 6L6GC's (cheap as compared to KT-66's etc.). And of course, Telefunken 12AX7's are to die for. The best sounding of all time I think.

A magic combination.

Go here for a picture:

http://www.sundial.net/~rogerr/amplif1.htm#mc30

Here is a close up:

http://www.geocities.com/SunsetStrip/Alley/7458/MacMC30.htm

 

Any idea what those big glass 1614/6L6s are in the amp in this picture? And I wonder what those black things under the amp are -- they sorta look like black Isopods.

 

They are Genelex KT-66's. A very expensive tube that Steve feels sounds dreadful in a McIntosh MC-30.

This guy doesn't think so, but he probably hasn't thought of trying a cheapie GE 6L6GC yet!

 

I rolled some Mullard 12AU7s into my Rogue 66 Magnum last November producing similar results to those you described. Later found some military versions of the Mullards providing even better results. The Telefunken 12AU7s were a bit more dynamic, but a bit glassy by comparison to the Mullards.

Since Mullard EL34s are now too expensive for mere mortals, I've settled on the Valve Art version of the tube. It more closely resembles the sonic signature of the Mullards than the Tesla, Svetlana, Sovtek and Siemens tubes do in my Quicksilver MS-190 (which uses 4 EL34s per side).

Need some help finding some NOS 7308's. I just retubed by amp's DC coupled input cards with some Sovtek 6922's, but these just aren't getting the job done. The sound is thin and lifeless compared to the old Amperex 7308's that Quicksilver used to provide.

 

I've really been devil's advocate about Mullards, but I've come around and through the forest at least twice in two years. So, I'm here to say, Mullards and most NOS tubes are best in just about any application.

Russians get flaky over a short period of time. They DO sound great in my Dynacos, but guess which ones sound more musical?? Yup, those expensive, hard to snag NOS buggers. Mullard your amp and basically forget it. They're stable as a rock, sound "flavorful" with great tone, and I've rarely had to re-bias an amp with a Mullard.

You COULD buy 4-6 sets of Sovteks, or just get the blasted Mullards and have less to worry about.

The 12AU7 Mullards are great but I've rolled a few RCAs and Amperex's that did wonderfully too. Each amp and application defies a steady decision of what tubes to use in general. Roll on!

Oh, Chinese makes, Teslas, most cheap tubes - beware. Keep away!

 

Now, are these GE 6L6GCs you're talking about the ones that are black metal? Or are those the RCAs?

And how can tubes be made of metal? That seems weird to me. Is it even a tube if it's not made of glass?

 

Many tubes were made of metal in the old days. They didn't shatter like glass tubes.

Forget about the metal RCA 1614's. Forget about the expensive black plate RCA 6L6GC's.

If you have a McIntosh MC-30 or MC-40 or 240, use GE 6L6GC's (GC stands for "Glass Case"). Steve sez these are the best for Mac's, and he oughta know.

 

Thanks for the quick info, John. I think I'll work on getting a quad of those GE 6L6GCs as soon as I can.

My MC-30s and I thank you. My checkbook, however, is a little nervous. But not nearly as nervous as when I whisper "300B" or "Mullard" to it .

 

Well, I think GE 6L6GC's are very cheap (at least compared to everything else). Maybe 25$ each or something like that? A Genelex British KT-66 is now $400 per quad. Urggh.

Upscale Audio probably has some nice GE's. They have a link on Steve's homepage.

Good luck.

 

Just thought I'd add my two cents to this. I am following these tube recommendations with my McIntosh MC30s. As I said in an earlier post, I rolled in Telefunken 12AX7s and was very surprised.

And last week I popped in four GE 6L6GCs (to replace Sovteks in one amp and RCA blackplates in another) and the amps got even more transparent and detailed. And the GEs glow so brightly, they're prettier than the blackplates.

Next to be replaced are the 12AU7s!