Best 6L6GC out there now for high gain channel switcher?

[FourT6and2]

Both Ruby and TAD are just rebrands of other manufacturers

Nope. The TAD 6L6GC-STR and the TAD 6L6WGC-STR are made specifically to their own proprietary specs at the Shuguang factory in China (most likely by the Valve Art guys).

A real sleeper 6L6 variant tube for high gain is the old short bottle Sovetec 5881's if you can find a set as they are very focused smooth and musical sounding in fact one of the very best sounding 6L6 variants I have heard in a high gain amp. Now we are not talking the full size 5881 labeled Sovetecs here as they are shrill and harsh.
These are the ones I'm talking labeled here Mesa but these are Sovetecs.

As far as I can see, those are the exact same tube as the ones you think are "shrill and harsh." Maybe I'm wrong, but the only difference is the plastic base. Same exact tube, though. The "wafer bottom" version you have pictured is for sockets that don't use clamps. The other version, with the larger full-size base (the WXT) is for sockets that have clamps. Neither tube was made for audio. But they are robust. Soldano uses them as stock. And most people find them to be shrill and harsh either way.

The Sovtek 6L6WXT+ is killer. It's tight and crunchy, so I can't see you having an issue with boominess. As for treble, it's not dark by any means, but it's not shrill either. The fact that they're cheap and last forever is nice too.

The WXT is the same tube as the WGC. Just different base. They are robust and can handle some high voltages. But a lot of folks find them to be a bit sterile depending on the amp. It's all opinion at that point though.

 

[FourT6and2]

I should say I'm currently using the Sovtek 5881/6L6WGC wafer-bottom in my SLO Clone. But I'm probably going to try the TAD 6L6GC-STR. I've heard good things about the Ruby MSTR as well. Although, ideally I'd go with the SED =C= if they weren't out of production. Prices for a quad of those are up around $200 now and like someone else already said... they are most likely factory 2nds or B-stock at this point so not worth it.

 

[Dale B]

I should say I'm currently using the Sovtek 5881/6L6WGC wafer-bottom in my SLO Clone. But I'm probably going to try the TAD 6L6GC-STR. I've heard good things about the Ruby MSTR as well. Although, ideally I'd go with the SED =C= if they weren't out of production. Prices for a quad of those are up around $200 now and like someone else already said... they are most likely factory 2nds or B-stock at this point so not worth it.

I have a Soldano SLO. Other than going to KT66's, you may not notice much of a difference between the Sovteks and others. The O'Netics transformers in your amp are pretty much right there with the DeYoung transformers. I went from the Sovteks to =C= to the Philips 7581A. There wasn't much of a difference. Per Mike and Bill's recommendation, I kept the bias right around 25 mA, so I'm sure that is playing a part in the lack of what I heard during any changes.

The feel changed slightly, but it wasn't drastic. The Sovteks had the "gooey" thing going on. I've always liked them in the Rectos, Marks and Naylors. The =C= stuff was always the "go to" tube for me. Now, they're all but gone. The Philips is pretty much the same vibe of the =C=, but it is just a touch cleaner sounding in other amps.

If you get around to changing the power tubes, I would love to hear of any differences you notice.

 

[FourT6and2]

I should say I'm currently using the Sovtek 5881/6L6WGC wafer-bottom in my SLO Clone. But I'm probably going to try the TAD 6L6GC-STR. I've heard good things about the Ruby MSTR as well. Although, ideally I'd go with the SED =C= if they weren't out of production. Prices for a quad of those are up around $200 now and like someone else already said... they are most likely factory 2nds or B-stock at this point so not worth it.

I have a Soldano SLO. Other than going to KT66's, you may not notice much of a difference between the Sovteks and others. The O'Netics transformers in your amp are pretty much right there with the DeYoung transformers. I went from the Sovteks to =C= to the Philips 7581A. There wasn't much of a difference. Per Mike and Bill's recommendation, I kept the bias right around 25 mA, so I'm sure that is playing a part in the lack of what I heard during any changes.

I don't know if I believe the SLO is magical in that other amps respond to power tube changes and it... somehow... does not. If you can hear sound coming out of the speakers, then the power tubes are at work and will influence the sound of the amp. Their job—as you know—is to amplify the signal so you can hear it. So even if they aren't being driven to the point of clipping liked a cranked Marshall, those tubes are still affecting the sound of the amp one way or another, otherwise there wouldn't be any sound coming out of the speakers. Sure, most high-gain amps get their "tone" from the preamp. The SLO is no different. But the power amp definitely has an affect, albeit small.

I've learned through trial and error that power tube changes in most amps yield very subtle results. So I'm not expecting something huge. But the stock Sovteks are a little... harsh. Maybe grainy or gritty are more accurate.

The super cold bias is also part of it in my opinion.

If you get around to changing the power tubes, I would love to hear of any differences you notice.

Absolutely. I tried to record a clip of my build this past weekend but got interrupted right when I was about to flip the amp on

 

[sahlomonic]

The Sovtek 6L6WXT+ is killer. It's tight and crunchy, so I can't see you having an issue with boominess. As for treble, it's not dark by any means, but it's not shrill either. The fact that they're cheap and last forever is nice too.

Laura recommended these when I was tube shopping last year. Couldn't be happier with them.

 

[Lution]

Wouldn't the JJs just add more bass and treble (something I'm looking to lessen)? Or is the bass tighter and treble more smooth on the JJs?

JJ's are the way to go. I've owned 2 of these amps, and JJ's were the ticket in both. They are far from bright, it will tame that very well. Just bias it properly, and a JJ in V2 & V3 will smooth the treble out that much more, and very noticeable. In fact, I found myself ADDING treble. Of course, cabinet makes a difference too..

They do add some bass, but it's much tighter, and more focused. Just back down the bass knob. I loved those amps! They ate my 5150III mini for lunch, at half the price! I'd take another in a heartbeat if I ran across one used at a great price.

I just tried a set of JJ's in my RD45 and it did exactly the opposite of what you said. lol. I biased both to 40mA and the treble was even more icepicky than the Rubys - unbearably so. The bass tightened up a bit, but I had to take them out and return them to the local mom and pop store.

The Rubys beat the JJs (for my taste in this amp).