As far as what tube.....well, there's tons of threads here about this. IMHO, TAD 6L6WGC STR's are solid great productions tubes. And Tung Sol 12AX7's have served me well so far. This is basically, what I would suggest for a solid set of cost friendly production tubes.

One thing, I did just check some prices and knew the prices have gone up considerably at the beginning of the year. But, I was a bit shocked to see just how much. The same set that cost me about $80 a year ago, now are more like a $100. BS as far as i'm concerned...but that's another topic.

OK, let's back up a little. I thought you had the amp in your posession.

Here's what I know about the Groove Tubes, I think most of it is correct. GT's are just rebranded tubes from any number of manufactures. Same thing as the TADs. The thing that most people don't like about GT is that they charge a whole bunch of money for selecting the best, but seem to fall short much of the time. While the TAD's seem to have the opposite track record.

The GT 6L6GE RI is suppose to be a replica of a GE US made tube. It very well could be that these specific GT's that your amp guy is using is sounding good and maybe you/he found a new cool tube to use. So price aside, if you really trust this guys opinion it might not be a bad thing.  The same deal goes with the EH tubes. They're just rebranded tubes also and some of the EH tubes are highly thought of for certain circuits but generally not what I see a lot of guys use for the D-style amps.

So the question is, did he try different tubes and found these to sound the best or was this the first set he put in and went with it? Maybe wait a little bit for some others to respond. Maybe someone has experience with the GT tubes in question.

Edit: Yeah biasing the amp is not a hard thing and worth learning how to do. You'll need a multi-meter of some sort. But it's doable.

The Groove Tubes in question are NOT made in the US. They are select picked Chinese Made tubes, much like the TAD's. Groove Tubes,

of course, was acquired by Fener, which is why almost every new Fender you buy has GT's in it.
Here is a post from TGP on the subject:
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"the Groove Tubes are supposed to be produced on original GE equipment"

The are not produced on the original GE equipment .... and never were. They are made in China and always were made in China.


There is some truth to the statement and some "Aspenism" to the statement.

The original design was followed and the micas were made by the same company that made the originals.

The plate material was at one time a reproduction of the 5 clad plate material formula but a lot of the time when production

needed to continue and the Chinese did not have plate material they used their own.

The grids, winding machines, and grid wire were Chinese.

The tubes were never made on the original machines. Those machines at GT were never used for any production at all.

The tubes orginally were screened "made in USA" but when Aspen was called on it and learned that he could be brought up on charges

for making false claims that line of print was removed from the tubes.

There were a lot of things Aspen told people at GT where initially we believed him. Over the years many of us learned that he was

basically making up his own story. I worked directly with the Chinese factory and saw the 6CA7 failures as well as the 12AX7M

failures over a number of years. I watched the GEs change radiators, use the wrong plate materials and saw other things as well

right down to the wrong bottles. Aspen would generally say he was going to do something about it but in the end the tubes were

just sold and it was hoped that chance would make things right in the future which rarely came to pass. In the case of the 6CA7

and 12AX7M things were not resolved at the time GT was sold to Fender.
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With all that in mind, consider that when I was first getting into tube amps when i was in 8th grade and high school back in the very eary 90's, Groove Tubes was pretty much it as far a source of tubes, other than Ruby Tubes, Radio Shack, and NOS until New Sensor acquired the Reflektor Plant and started pumping out tubes under the Sovtek name, and then under the EH name later on. I was lucky enough to have a stash of NOS preamp tubes, but when it came to power tubes, i either used Radio Shack or Groove Tubes, and i didn't have any issues that i can think of. I think there is alot of negative feelings regarding Groove Tubes amongst those of old enough to remember all the BS that Groove Tubes tried to feed us about their tubes being made here and so on and so forth. Alot of guys wouldn't use em, especially when NOS tubes weren't quite so pricey back in the day.

I can't say for sure which factory in China GT picks their Chinese tubes from, but there have so many mixed reviews on them
compared to TAD who sources theirs primarily from Shuguang, that I never have been tempted to try them. Their russian line of

preamp tubes, however i like for use as a PI tubes and even as good balanced workhorse preamp tube.

That being said, it couldn't hurt to try them. You may end up liking them.

Gregg

Any time, man.

As far as tried and true, new tubes, the TAD's have been used with quite a bit of success, in the Ceriatone Community, and in other amps circles as well, as have the Winged C's (SED). I have read good things about the Tung Sol 6L6GC-STR, and that's what i'll be trying next. The stock JJ's can be a good baseline to get to know your amp, and make sure everything is wired properly and functioning correctly.

For NOS, you can't go wrong with RCA blackplates and older GE's, both 6L6Gc's, of course, if you can get em. I have also heard great things about the JAN Phillips 7581A and the Sylvania STR415's which were made for Mesa. They are both very clean, heavy duty tubes which really don't break up, which is great for D-Style amps, as the bulk of the OD tone is from the preamp. They are pricey, though, which is why i have never tried em.

As far as preamp tubes for new production, the Tung-Sol "reissues" are supposed to have great tone, i haven't used em yet, but Chris (SoundPerf) uses em, and if you listen to his clips, they sound excellent! Just be sure to buy em from a dealer that screens em and tests em thoroughly, like Mike from KCA, as they seem to have about a 50/50 failure rate. Pretty high for a new production tube. The Mullard and EH "reissues" get great reviews as well, and each has their own strong suit as far as tone. The Tung-Sol Reissue, the Mullard Reissue, and the EH Reissue are all made by Reflektor/New Sensor in Russia, who also make Sovtek as well. New Sensor bought the rights to those trademarks, and Sveltlana and manufactures all of them. Each one has its own vibe, though so it's not like if you buy an EH it will sound like a Sovtek, etc. TAD tubes are also pretty well regarded, and most fo their stock is screened, picked, tested, and re-labled Shuguangs from China, and have proven to be reliable. Their 7025 is very quiet and stable, and nice for use in C-Lators.

NOS preamp tubes opens up a HUGE can of worms, and there are quite a few choices out there, each with their own voice and drive characteristics, and everyone has an opinion on which sounds best. They can cost anywhere from $28- $200 US a tube. Some of the best, subjective, i know, are right in the middle, around $50-$65 US.

Looking forward to hearing how you like the amp. Hope you get it home and up and running soon, and I hope this info helps!

Gregg

Here's the response on my questions about the tubes in question:

"The GE Clear Top Tubes were one of the best 6L6 of their time, noted for their sparkle and great frequency response.  All current production tubes are made either in China or Russia or somewhere in the former USSR – there are no tubes made in the USA anymore.  The Groove Tubes, just like the TAD’s, are selected from the best of the best (Chinese or Russian,) then repackaged with their name and given a rating when matched.  I don’t know of anything higher quality than what I picked for you.  I use Electro Harmonix and Tung-Sol 12AX7’s in all my builds, except when the customer requests NOS tubes and is willing to pay a lot of money for them.  The only ordinary tubes on the market are junk Chinese and JJ tubes.  They are cheap and sound like it.  All the tubes we use here are very high quality for current production tubes and I only select the best of these.  I already had the Tung-Sol tubes, but I had to order the TAD’s.  I ran out of them and didn’t re-order since everybody has been raving about the tube brands I do install, but they will be here tomorrow, along with the relays and I’ll try them out.

There really isn’t anything custom about tubes these days.  Builders have about 4 or 5 brands to choose from, all made overseas, however some of those brands have proven themselves to be better than others which are the tubes we use here."

So, I'm going to have him put in the TAD's and Tung-Sols and see what happens.

It's really hard having someone else pick and choose tone becasue everyone has different ideas as to what sounds best. I think this is a good place to start though.

I'm also going to ask him about the matched triodes on the phase inverter.
I have a question though:
After the triodes are matched, the phase inverter needs to be balanced? Is this correct?

Thanks for all the help!

Wow, it was hard staying with that thread, but great info, thanks.

I asked about this and he said he does this already with the phase inverter so the amp should be good to go. He's also going to try the TAD's with the Tung-Sols and then let me know the tone difference between them and the G.T.'s and EH's.
This guy seems to know his stuff so I'll trust him to give me what's best for the amp. When I get it, I'll do what's best for my amp....lol

If only my guitar playing was as good as my knowledge of tweaking these amps  actually, my knowledge is limited to tubes, speakers and a few simple tweaks. if i tried to build one of these or do any major work, i would prolly electrocute myself 

Gregg