Question for Tube Heads

[Jim Alfredson]

Anyone try the new Tung Sol 6550 re-issues?

[AllenLowe]

haven't tried those - but I have tried other highly touted current production tubes and they almost all suffer by comparison to NOS - the only new tube I like is the TAD 6L6, which sounds as good as my old GE's -

[Jim Alfredson]

I'm looking for something for my Leslie 122 amp.

[jazzbo]

I believe these have absolutely no relation to the original Tung-Sols, they're just new tubes branded with the old label which was purchased, as was Mullard, etc. by an unscrupulous business hack who makes no effort to recreate original design, just labels inferior tubes with a time-honored name or two.

New old stock is the way to go. I've had decent experience with POWER tubes from JJ Electronics and SED (formerly Svetlana, but not the NEW Svetlana which is part of this bogus new name on inferior tubes megabusiness) but I've had no real success comparing input tubes of new production to NOS tubes; NOS tubes win hands down every time.

Admittedly, I'm not using them in Leslie cabinets, and I don't know how crucial that position in the circuit is on a Leslie amp, but in my audio amps I've given up trying to use new production input/driver tubes.

[wolff]

Anyone try the new Tung Sol 6550 re-issues?

No, my old stock, no hole, grey plates are doing fine. Always liked the EI KT 90's for new stock.

[wolff]

Kevin Deal at Upscaleaudio.com may be someone to talk to.

How many 6550/KT88 does the amp use?

[Jim Alfredson]

Just two.

[wolff]

Have you tried many different types in the Leslie?

[Jim Alfredson]

No... I hear the old Tung Sols are the best, and indeed Leslie actually used them in their stock Leslies (and the tubes have the Leslie name on them).

Like I said, I'm not sure what's in there now... I don't think they are stock. I have the newer Hammond-Suzuki 122 amp, which is identical to the old 122 amps, but all new parts. The stock tubes in that were horrible Chinese crap so my tech put in some new Russian tubes (I think). But they are on their way out... for reasons not relating to the tubes themselves... just the rigors of the road.

[Jim Alfredson]

Man, doing some reading on the 'net and looking at pictures, I'm beginning to think I have Svetlana 6550C tubes in my Leslie right now, which are supposed to be about as good as you can get for new tubes. I guess I should go unload the van and take a look.

The old Tung Sol 6550s are supposed to be the best for Leslies, from what I've been reading. Maybe the thing to do is keep my Svetlana's for the road and buy a pair of NOS Tung Sols for special occasions (like the upcoming recording sessions).

All I know is that I have a quad Tung Sol 5881's in my Leslie 21H which I keep in my home studio, and that Leslie sounds amazing. I have another 21H amp with GE tubes in it, and I've swapped the tubes out and did comparisons and the Tung Sols blew the GE's out of the water.

More research...

[Jim Alfredson]

So I just checked the 6550s in my 122... they are indeed Svetlana 6550C tubes. However, the amp uses two 12AU7... one for the Leslie motor control circuit, and one for preamplification. So one of those tubes is very much a part of the sound of the amp. In my Leslie, both are new chinese tubes.

On a whim I went into my garage and looked in the back of two Hammond M3 organs that I have, which I do not use. I have them mainly for parts. In the preamp of one I found an RCA 12AX7 and an RCA 12AU7. In the preamp of another I found...

Tung Sol 12AX7 and 12AU7!! Woot! So I'm going to stick that 12AU7 into the Leslie 122 amp and see what difference that puppy makes!

I'm still seriously considering getting a NOS Tung Sol 6550 pair for recording, even though they are upwards of $115 per pair.

[wolff]

There are 3 different types(construction wise) of Tung-Sol 6550's. You'll have to decide which kind to get. More research...

Access to a tube tester?

A very good and still affordable NOS 12AU7 is the RCA cleartop. I've seen many in old organs at the Goodwill.

I'd call Kevin Deal and see what feedback he's gotten from others with Leslie speakers, especially regarding the 12AU7 and 12AX7. He says 90% of his business is to musicians.

[Jim Alfredson]

wolff,

Today before rehearsal started, Joe and I swapped out various old 12AU7's that I have, including the Tung-Sol I found in my Hammond M3.

I tried the Tung Sol, two different RCAs (one with red lettering, one with white), two Sylvania's (one with green lettering, one with yellow), and a couple different Amperex tubes. I also tried the Tung Sol 12AX7.

Our favorite was the Tung Sol 12AU7. Perfect blend of high end clarity without being harsh and a smooth midrange. The RCAs were very similair to each other and were a close second.

Sticking the Tung Sol 12AX7 in there was very interesting... it was louder (to be expected) and as such it added a nice, growly tone to the Leslie. I may have to experiment more between the two Tung Sols. The 12AU7 was very clean and beautiful sounding... the 12AX7 was a little dirty, which is not a bad thing.

[Jim Alfredson]

Interesting 'review' of the new Tung Sol re-issues:

And now - to the extreme consternation of the Glass Snob

Contingent, and to the delight of the folks who listen

to the tone and not the printing on the glass - I'm happy

to announce the introduction of the new Tung-Sol 6550.

That's right, I said Tung-Sol. This is a new-producion

tube from Mike Matthews/New Sensor, and it bears the

Tung-Sol trademark, which Mike owns the rights to. It

shares the plate structure of the venerable Sovtek 6550WE

(which, BTW, is larger than a stock Tung-Sol's) albeit

using a different alloy sandwich. It also uses only two

vertical support rods instead of the three used by the

old Tung-Sol or the four used by the 6550EH and KT88-EH.

Like its ancestor, it has a triple getter system, with

one top and two side getters. The grid radiators (two

sets, top and bottom, like the original) are quite a bit

larger than the old ones. The more massive plate and

larger grid radiators certainly add credence to New

Sensor's claim that their new Tung-Sol 6550 can deliver

more power than the original. Pin one is connected to

the metal base ring (like the original) so anyone wanting

to use this tube in a Fender-wired socket should take

note - unless you rewire the sockets so that the grid

swamp resistors are flying in the air from pin 5 (like

on a Marshall) you'll have your bias voltage on the outside

of the base ring. If a butterfly clamp comes into contact

with it, you'll have a fat repair bill. (6L6s have no pin

in the #1 position, so the #1 socket connection is often

used as a tie point for the swamp resistor/bias feed.)

Other interesting facts - the screen grid in this tube is

*super* beefy - gold-plated, and carbon-coated. JC, the

head design engineer at New Sensor, said that they paid

particular attention to the screen, because the screen

grid is the most likely failure point in any power tube.

Appearance-wise, they got the bottle perfect; it even

has the "stop sign" tube-ID number on the top. The micas

are thicker than the original, and of larger diameter.

So- how does it sound? The only thing I had in the shop

at test time that uses two 6550s was one of my Leslies,

which is hooked up to my A-100. (An A-100, for you string-

plinkers who may not know anything about manly instruments,

is a B-3 with speakers, amps, and reverb built in.) I had

a couple of 100W Marshall heads in for service that were

set up for 6550s, but the four I got were pre-production

samples, and I was lucky to get a pair out of 'em that

was even close. (6 mA apart.) Since my Leslies are all

loaded with the original Tung-Sol 6550s, and since I've

never used anything else (except in an emergency or for test

purposes) and I've been listening to those Leslies since 1965,

I have a pretty good idea what Tung-Sols sound like in my application.

I stuffed the pair into a 145 "Memphis" style Leslie and fired

up the A-100. A 145 Leslie is the short-box version, using

a 147-type amplifier. It is in all respects identical to a

147, except for the size of the cabinet. And, before you ask,

a 147 has the same amplifier circuitry as a 122, with the

exception of the single-ended (unbalanced) input stage.

The other differences have to do with how the motors are

switched on and off, and don't affect the tone. A "Memphis"

Leslie has a top rotor which can spin fast or slow, and a

bottom rotor which can spin fast or not spin at all. It's

called a "Memphis" setup because that's how Booker T always

ran his Leslies with the MGs.

Once the organ rig was warmed up, I laid into it big-time.

I ran some finger bass and kicked some pedals, played

chords on the lower end of the manual, and did all manner

of other nasty things which are hard on the tubes. A 145

(or 142, which is the same box with a 122 amp installed)

is a particularly good testbed for 6550s, because the

shorter box kills off some of the bass response, and a tube

with no nads will sound extra wimpy in this situation. Aside

from the fact that the bass end of things was tighter and

that the organ snarled a bit better in the midrange with Mike's

new Tung-Sols, I couldn't hear any noteworthy differences.

The (original) Tung-Sols I currently run in this Leslie only

have around 200 hours on them, which is *nothing* for those

tubes. (I still have some that spent 15+ years on the road,

and they still test great and sound fine.) While I can't speak

for the service lifetime of the new ones, they do pass a life

test on my Hickok. No rattles or other nasty artifacts that

I could hear, and Leslies are especially good at bringing that

kind of stuff out, since the power tubes live only 8" from a

roaring 15" woofer and a large spinning baffle.

Preliminary testing leads me to believe that this is a KICKASS

tube. When I can get some real production stock, burn 'em in

and do my usual QC and matching, I'll put a set in one of my

SVTs and we'll see how they survive in high-voltage land.

Mike says he should be able to start shipping on September 15th.

No pricing is set as of yet. As for the pair I put in my Leslie,

I think I'll leave 'em there. They sound great.

Now that the Glass Snob Contingent has had a chance to stop

wheezing and sputtering for a few seconds, I'll drop a hint:

if you think a current-production Tung-Sol 6550 is sacreligious,

just wait - you ain't seen nothin' yet. Further details in

about two or three weeks, and have your Kleenex boxes and

tranquilizers ready, kiddies. ;-)

Lord Valve

I found this on the alt.music.hammond-organ list. Obviously to be taken with a grain of salt, but it sounds promising. I've noticed some online Hammond dealers are selling these now and proclaiming good things. It might be worth giving a pair a shot.

[wolff]

One thing....you are swapping out 12AU7 for 12AX7 in the same 'spot'? If so, can you do that without causing problems with the amp?

I know I like certain Mullard 12AU7's in my audio gear. Maybe another to try.

[Jim Alfredson]

12AU7, 12AT7, 12AX7... all the same thing. You can interchange them. There are differences, but they are negligable. The main difference is the gain. The 12AU7 has the least, the 12AT7 has more and the 12AX7 has even more. I think... I know the 12AX7 is the hottest of the bunch.

I've got some new Electro-Harmonix 12AX7s I should try in that amp. Although the Tung Sol sounds so good, I think I'll just leave it!

[wolff]

I'll add that I've used Sovtek 6550WE, Svetlana 6550C, EI KT90(drop in, in most cases, for 6550/KT88) and NOS Tong-Sol 6550's in my amps, and the winner is the Tung-Sols with the KT90's second.

[Jim Alfredson]

Hmmm. Just found this on google:

Do you think that I can replace tubes 12AU7/SBQ5 with 12AX7 in a power amp

without modifications

."

The short answer would be most likely not in the majority of applications.

The problem is that a 12AU7 is a medium mu tube (mu factor 20) versus the

12AX7 which is a high mu tube (mu factor 100).  Placing the 12AX7 into an

application designed for a 12AU7 would in most cases result in to much gain

& problems for the circuit.  You did not say which function the 12AU7

performs in your power amp or the type of power amp.  It is very typical for

the 12AU7 to perform the phase splitter function in a push-pull amplifier &

in that case it would be a terrible mistake to place the 12AX7 into the

circuit.

There are some cases where you could get away with it but that would depend

on the circuit.  Unless you really understand the circuit I would strongly

advise against it.  The ECC82 has been returned to production & is a direct

replacement for the 12AU7.  I think Ned at Triode Electronics has these

available brand new in the JJ Telsa brand for a very resonable cost.  The

12AU7 is also available in other brands & sticking with the same tube would

be your best bet

I didn't have any problems in my Leslie. Like I said, the tone was different and the signal was definitely hotter, but it didn't seem to have any adverse affects on the amp. Then again, those amps are built like brick shithouses!

[wolff]

12AU7, 12AT7, 12AX7... all the same thing. You can interchange them. There are differences, but they are negligable. The main difference is the gain.

Okay. Pretty much a no no in my audio gear, that's why I was wondering.

[wolff]

I didn't have any problems in my Leslie.  Like I said, the tone was different and the signal was definitely hotter, but it didn't seem to have any adverse affects on the amp.  Then again, those amps are built like brick shithouses!

It may not be damage that happens right away. It may just cause the tube to fail, or something worse. I'd check with your tech guy or someone who knows the Leslie amp you are using.

Edited February 28, 2005 by wolff

[wolff]

Yes, Ned at Triode is another who can steer you straight. Are you visiting Audioassylum/tubes??

Edited February 28, 2005 by wolff

[Jim Alfredson]

I didn't have any problems in my Leslie.  Like I said, the tone was different and the signal was definitely hotter, but it didn't seem to have any adverse affects on the amp.  Then again, those amps are built like brick shithouses!

It may not be damage that happens right away. It may just cause the tube to fail, or something worse. I'd check with your tech guy or someone who knows the Leslie amp you are using.

I had an emergency once were one of my 12AU7s went out. My tech said to replace it with any of the 12**7 series and it would be fine. Leslie amps aren't picky!

[wolff]

How about the holy grail of 6550/KT88's the GENALEX GOLD LION KT88 used in Leslie's??

LINK

Edited February 28, 2005 by wolff

[Jim Alfredson]

How about the holy grail of 6550/KT88's the GENALEX GOLD LION KT88 used in Leslie's??

LINK

I read something funny about those tubes just last night... supposedly when they first came out they were much cheaper than Tung Sols and touted as a good replacement for Leslie amps. Supposedly a lot of people tried them and discovered they actually sounded like shit in that application.

Now they are worth $$$$! But they still won't sound good in a Leslie amp. In a hi-fi amp, yes.

[Jim Alfredson]

Dang... looking at all these pictures of Tung Sol 6550s I just remembered that a Leslie 147 amp I sold to a friend of mine two years ago had the "coke bottle" tubes in it...

I didn't know any better. I sold it to him cheap, too becaue he's a friend. Dang.