Groove tubes

[burner]

I noticed on the GT website that they are listing some of the tubes as "U.S. Made"
I didn't realize that there were any uS manufactured audio tubes anymore.
where are they made (specifically) and does anyone have any more info regarding them?
Are they good?

I've really been liking the JJ tubes for a while, they sound great, IMO. any reason to try the US GTs?

[Greenbacker]

I thought they were rebranded Chinese tubes...

[burner]

For the record, not all GTs are made in China.

From reading the website I am under the impression that the GE copies are US made.....either that or they bought the US tools and sent them to china.
Does anyone really know?

What do you think of the quality/sound of the GEs?

[stratman_el84]

GT makes a number of tubes in a factory in California. The ones they make are about 90% US content, which is about the same as GE and other makers' content was when they were producing tubes.

A good number of GT's are made overseas, but many are made on different, GT-specific tooling and to different specs than the "house" brand.

Here's a copy of a post on another forum made by Myles Rose from Groove Tubes:

================================================== =======

From Myles Rose:

To all of you folks on this ....

GT makes their own 6L6GE. If you go to the GT website in the area of the GE, I have some photos of production.

The GE 6CA7 is about 6 months away. The tooling from the GE Owensbourogh KY plant was purchased when this plant shut down.

GT is financially involved with the JJ factory and the main tube factory in China. Tooling was specifically designed by Groove Tubes for some of these tubes. If you look at a JJ E34L and hold the GT version next to it, you will see the GT tube has a more massive plate assembly, with welded heat sinks on the plates. This is a 30 watt tube, all the other EL-34's are 25 watters. This is the tube used by Slash, Billy Gibbons, Joe Perry, Joe Walsh, Matchless and Bad Cat in their EL-34 amps.

The JJ KT-88 is also different from the GT KT88SV. Again, different plates, much larger wings on the plate assembly that are even easier to see, as they are at an angle, four of them. This tube has the same curves as the GEC Gold Lion. The other KT-88's curves are different.

The Chinese 12AX7C GT tube is off GT tooling, and it is a 9th generation tube. If you want me to show you the difference, if you are local, this is pretty easy to do.

On GT preamp tubes, they are tested for low output, noise, and microphonics. The reject rate is over 50%, hence their sometimes higher retail cost.

The power tubes are tested dynamically, not statically ( I have done articles on this a lot in the past, and it's somewhere on my website). They are also tested for gas leakage, grid leakage, and low vacuum.

From the GT website ( http://www.groovetubes.com/tubes.cfm ) this is gone into in a bit more detail than space here allows.

The folks that use them:

http://www.groovetubes.com/f-n-r.cfm .... which is why I get a lot of free tickets for folks that sit and wait until I finish my work with a lot of these folks.

On the other tubes, at one time, I made up a list. I will try to copy it here, but lord knows how bad the formatting will come across....

Here is a bit of text that may help.... this may be a bit out of date .....

12AX7C - China, new tooling with a few spec changes specific to GT.

12AX7R - Russia, Reflector Factory, east side of the Reflector factory where the
Sovtek 12AX7WA/WB is made.

12AX7R2 - Russia, Reflector Factory, on the east side of the factory where the
Sovtek 12AX7LP/LPS are made.

12AX7R3 - Russia, Reflector factory, west side, new tooling, same as the Electro
Harmonix (sold by Sovtek in their EH division ... and Sovtek is not a tube company,
but a NYC company doing business with Reflector) This is the same as the 12AX7EH.

12AX7A - no longer in stock, the USA 12AX7 tube that used to be at a higher retail
than the other 12AX7's.

ECC83 - from the JJ factory

7025 - from the Ei factory made on the last tooling that was used to make the smooth plate
Telefunken. Ei also made many OEM Siemens, Mullard, and telefunken tubes

12AT7Y - Ei

12AT7C - China

(by the way, on the latest GT pricelist, there is a legend at the bottom where they tell where
the tubes are from country wise)

12AU7 - Ei

6V6R - a newer Russian 6V6 that is from the same tooling as the Electro Harmonix 6V6.

6V6C - a new 6V6 off new tooling that is holding up to higher plate voltages nicely and has
a sound more folks are starting to prefer than the 6V6R in more cases all the time.

6L6CB - Chinese, softer vacuum, coke bottle shape.

6L6B - Russia, Reflector, sometimes called the Sovtek 5881. Sturdy tube, maybe the
most strong from a physical standpoint, great for touring stuff that gets thrashed by
heavy handed road crews. This is the stock tube in currently manufactured Fender
amps. This is also known at times as the Fender 6L6GC or the 6L6WXT Sovtek.

6L6S - from the JJ factory but rebased and re-pinned if or when they come in with
stamped pins with dipped pins that tear up some sockets. The rolled polished pins
are also tapered. A bit of an extended midrange that a lot of heavy rockers love.

6L6R2 - The Svetlana 6L6, a tube I personally liked a lot, but date codes from 2002 have low vacuum and problems, so for Svets, know your vendor!

5881A - NOS, Tung-Sol - Great in Fender Black Face amps for a lot of my
Blueprinting clients. The tube used a lot in Black Face Fender amps as
original. They also used the Sylvania STR-387 and GE. This tube is now usually the JAN Philips rather than Tung Sols at this time I believe.

KT-66C - China, the KT-66 that folks like Valve Art and others sell as the KT-66.
Good to about 450 volts B+.

KT-66HP - Russia, built under contract for GT to GT specs. A copy of the GEC tube.
Handles higher plate voltages than the KT-66C and has a different getter assembly.
Great to 525 volts, and the tube the Dr. Z Route 66 was designed around. The
tube to be used in Marshall JTM-45.

6L6GE - made in California by the GT factory with USA parts and labor. This
was the tube used in the four Fender Showman heads at the 1968 Hollywood
Bowl concert by Jimi Hendrix. (not always a Marshall guy)

EL-34C - Chinese EL-34 (25 watt tube) By the way ... (added for this post), Chinese output tubes used to be about 20% down on power from the Russian ones. Now they are 15% above.

EL-34R - Reflector (Russian) EL-34 (25 watt tube) sometimes sold as the EH tube.
Pretty linear and Mullard like in some aspects of its character.

EL-34R2 - Svetlana (Russian) 25 watt tube, used a lot as standard in Rivera amps.
This is a stronger tube then the R or C. (as of July 2002 it is not as stong as the Chinese).

E34Ls - JJ factory but with a GT developed heat sink assembly extruded onto the plate
assembly. Hold up a JJ and a GT and you can see the difference without any sort of
equipment (with the eye its easy). This is a 30 watt tube and bias should be
checked and adjusted when one uses these. Very high output and strong mids.
Used by Gibbons, Perry, Walsh.

6CA7 GE - the next USA tube on the GT list to go into production with a higher
vacuum than the softer vacuum Europe style of tubes that use a diffusion pump
for vacuum rather than a turbo-molecular pump in manufacture. ... also has an
active beam forming assembly as a 6L6, rather the passive beam forming
element of a normal EL-34. One of the only tubes that will hold up in
Music Man amps that have over 700 volts on the plates.

6550A - USA NOS GE no longer in stock. The strongest of all the 6550's.

6550C - Chinese and a fun tube, as you can get these to distort in amps
where the 6550A would not.

6550R - Russian 6550, takes longer to distort than the Chinese, maybe
somewhere between the A and C. ( June 2002, Chinese is stronger).

KT-88C2 - Chinese KT-88

KT-88-SV - JJ tube that has a different plate assembly with a large heat sink
welded to the plate. It may have a different base, pins, at times if necessary.
There is also a KT-88 that is a JJ tube that is stronger by a wide margin than
the original Gold Lion GEC KT-88. It biases differently. The KT-88SV (think
of the "V" as "vintage" ... where the output of this tube and design was redone
to copy the GEC Gold Lion.

EL-84R - Reflector Russia (as the Sovtek)

EL84Y - Ei

EL-84S - JJ

7027 - JJ

7591 - Reflector, Russia.

............................

GT also rebases a lot of power tubes. Some come with stamped pins with dipped plating, that is rough on vintage sockets. GT's pins are rolled and electroplated or polished.

Hope that helped [Smile]

--------------------
Myles S. Rose

================================================== =======

Facts are great things to know!

Strat

[burner]

Excellent post, thanks for sharing!

The GT 6L6S looks like it might be my next investment as I've been really happy with JJ tubes thus far.

For a while I was beginning to think I posted this in the wrong section......

[stratman_el84]

Originally Posted by burner

Excellent post, thanks for sharing!

The GT 6L6S looks like it might be my next investment as I've been really happy with JJ tubes thus far.

For a while I was beginning to think I posted this in the wrong section......

Hey, your very welcome! Glad to have helped.

I'd also recommend the 6L6GE's. I've put them in a number of amps for people. As Myles stated, they're not as mid-rangy as the 6L6S's. They're very balanced, have tons of power, the lows are tight and thundering, and the highs are sparkling.

They're very dynamic and have lots of headroom. They also seem to take higher plate voltages well, and last quite a long time without going "thin". They would be my choice for a Twin Reverb or a Super Reverb where the amps would be gigged at significant volume regularly. Good luck.

Cheers!

Strat

[scottywompas]

I'm not sure which tubes are manufactured in the US but they definatley do have the equipment here in California. I had the good fortune of having my old Bandmaster worked on by Groove Tubes and when I went to pick it up I got a little tour of the facilities.

I use the 6l6GE's in my band master and I know at least those are made here.

Scott

[GuitarBrent]

Originally Posted by stratman_el84

Hey, your very welcome! Glad to have helped.

I'd also recommend the 6L6GE's. I've put them in a number of amps for people. As Myles stated, they're not as mid-rangy as the 6L6S's. They're very balanced, have tons of power, the lows are tight and thundering, and the highs are sparkling.

They're very dynamic and have lots of headroom. They also seem to take higher plate voltages well, and last quite a long time without going "thin". They would be my choice for a Twin Reverb or a Super Reverb where the amps would be gigged at significant volume regularly. Good luck.

Cheers!

Strat

Yeah except mine went microphonic after about 50 hours of playing them. They sounded great before they croaked though. Too bad I've had them more than 90 days or they'd still be under warranty.

[Big White Tele]

Ive got a pair of Groove tubes 6l6gc tubes that say USA on them. Now I bought this amp 2 years ago from Pete Anderson, Im thinking these were Sylvania or RCA's that GT matched and labelled for him, but I could be wrong. Wasnt this before GT started making there own? Ironically, 1 is now microphonic also. But they still do sound very good. Im in need of a replacement set, and would love to know what these are. I'll try to get a picture.

[stratman_el84]

Those are probably some of Groove Tubes' US factory production, as the 6L6's were one of the first power tubes that Groove Tubes put back into production in the USA around 2002. Here's a copy-paste about Groove Tubes USA production concerning the 6L6GE:

"Groove Tubes bought it's present building in August of 2000. The new GT home has close to 12,000 feet of office, lab, and manufacturing space and is located in the small town of San Fernando, California. The new building has allowed expansion into actual tube production, and Aspen was blessed to be able to acquire the entire production line from the old G.E. company upon it's closing. This line will produce the original GE 6L6 and 6CA7 power tubes to the original specs and sound. Actually, at NAMM 2002 in Anaheim GT proudly introduced the first effort from this adventure, showing the new GT6L6-GE to rave reviews...it was generally confirmed this new GT tube is the exact equal of the famous 6L6."

Cheers!

Strat

[Big White Tele]

Perfect. Thanks very much for that info. I just assumed they recently started building them. Thanks again!

[Gtrman100]

I know GT gets slammed around here a lot from the connoisseurs of tone, but I think a lot of it is really unfair. It's probably the boutique vs production snobbery syndrome; GT provides tubes for Fender, Carvin, etc., so how could they be good?

I picked up a Hotrod Deluxe a few weeks back, needed a lightweight rehearsal/ small gig amp and the original ('99) tubes were shot. Popped in a set of GT6L6GCHD's, which I believe is a reproduction of the RCA 6L6, and it sounds great!

Punchy, sweet, with a really warm bottom end. I don't know why someone would slam them, but I see posts in this and other forums that just hate them! Probably from someone who wants to sell their own tubes.

I've used GT tubes for years(had a bad one or two also) in my Marshall's, Matchless', and other amps and think they're as good or better than anything else out there.