After a lot of experimentation I've found that the 6CG7 tube is my favorite "driver" tube in my SEWE300B, or at least the one I like the most with the rest of the tube complement (6085 pinched waist, 75C1s, Sophia Electric Aqua II 274B, Black Treasure 300B-Z).

I've tried a half a dozen types and the clear stand out for me is a Sylvania gray plate. . . rich but dynamic. I've tried RCA clear tops, Westinghouse, and several pair of differently branded Japanese, and I have a pair of Raytheon Japanese on the way (should arrive today).

Anyone have a favorite brand and type of this tube that I can consider?

Thanks. My purchase record shows I bought a pair of RCA black plates two years ago. . . but I have searched and only found one tube! I'll be on the lookout for another.

I found the clear tops to be a tiny bit tart and on occasion "sibilant." Nice in other ways though, I'm hanging on to my pair.

My 4th, 5th, 6th and 7th have been and will be mostly dominated by three visiting from out of town groups of in-laws. For the most part that's a good thing.

As always, thanks James.

I just did some bouncing around the net, looking at the 6cc42. Have you ever compared to the 6n3p?

I have wondered this for years, but have never looked it up, but it seems like any tube type, with a “pinched waist” is highly regarded. Why is that?

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I’m sorry, Lon. No more of these questions

The original question was, of those that have used one, what is your favorite 6CG7?

CAJames-  you mentioned these are compatible in place of 6922 tubes in Decware amps.  Including my Torii Jr v2? Anyone try GE tubes?

The GE tubes I was looking at were grey ladder plates with the dot matrix date coding etched on them.  Sure looks like 60’s vintage GE to me.

Fist try at 6CG7 is a pair of ‘66, ‘68 GE grey plates that tested 2600+ NOS.  Sounded very nice but I still prefer my ‘65 Amperex USN 7308 and RCA Grey Glass 6SN7 in adapters. Some stiff competition…Next up- I have a pair of RCA 6CG7 Black plates in route. These should be a true test how 6SC7 tubes sound in my Torii Jr within my system.  I gotta stop buying tubes…😩

Amperex 7308 are hard to beat in my experience, but you pay for the privilege of listening to them.

I'm generally not a fan of GE tubes, so very interested in what you think of the RCA black plates.

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Yeah, you and me both . Pass the candle.

I’ve been curious about the 6CG7 tubes and this thread has brought that curiosity back up again. I’ve currently got a 60’s white label Amperex 7308 in my UFO25 and an Amperex PQ 6922 in my CSP3 and these have been my go to tubes in those positions. I was considering using a pair of 6CG7’s in the output position in my CSP3, in place of a pair of 6N1P’s. Is this a good spot for them or are you guys mainly using these as gain tubes, other than in the Sarah?

Anyone know if 6GC7’s with 3 plates sound better/same/worse than 2 plates?  Any difference?  

CAJames-  these GE grey plates have grown on me or they are just sounding better with more hours on them.  I changed my rectifiers in my STR and they are sounding really quite good.  The reason I tried GE is this is the same gray plate vintage as 12ax7’s that were excellent- right up there with RCA blackplate 12ax7’s. At $20 /pair low risk.

When I started using 6CG7s in my CSP3 power positions, I had been using early 60s white label Valvo E88CCs with hallow getters, a clear, neutral and resolving tube with good space and fine detail. The 6CG7s I tried first were some Emerson labelled Sylvanias I think, having a line of copper grid posts running across the middle of the top mica, the only construction difference I can see on the Sylvania labelled pair I have being wires connecting the filaments.  

I tried a lot of tubes in the power position early on, finally gravitated toward early 60s euro E88CC types. My Decware order having been for a CSP2+, the change to CSP3 happened as mine was built, so it is one of the 1st CSP3s... not sure how long ago that was, but quite a few years. So my preferences for system/room tuning came with a few E88CC/E188CC types as part "my sound." Mullards or Phillips SQs with parasol getters, the Valvos I mentioned, and Siemens, both with halo getters were primary for years, the Mullards warmest, and Valvos and Siemens, different flavors of resolving and neutral. At least with all else the way I like it, these give variations of useful dynamic and complete balances that allow complexities of fine detail, space and speeds.

With the Emerson 6CG7 in direct comparison to these E88CCs, it had a warmer/slower baseline sound, softer and more weighted toward bass, a little restrained/held back most everywhere. Still it was pretty resolving, and an oddity, compared to rest being a little slow and veiled, the mids/upper mids were pretty present... All combined, they made a warmer, milder and more euphonic sound that felt a little off to me with that mid compared to the rest discrepancy. With direct replacements here, this seems to be characteristic of the tube, some more than others, the mids/upper-mids tend to push through the comparatively slightly recessed feel of all the rest. Interestingly, the bolder focus in the mids on its own make the mids pretty similar to good E88CCs. But in this softer context, the mids can feel a little sharp/forward.

Listening to this description, I would probably not try these tubes, but for me they had compelling traits even though they would not have won with my usual preferences if I had stopped at direct comparisons to my favored clear and balanced E88CCs and all else the same. Wanting to see what was possible, I avoided E88CCs, and was able to get to know the new tube type and adapt...

The Emersons had pretty nice complex resolution, under their warmish/slowish veils still letting me into the music in less obvious ways, but enough to want to try to wake them up more. And though the mids tended forward in these balances, especially on open recordings, I liked a lot of those mid qualities...if a little too bold, not particularly consolidated and hard... more being out of balance with the rest to me.



So I worked with other tubes first. Having played with this component in this system a long time, my choices ended up being variations on what I had used for years... For inputs mostly some resolving and open earlier Mullard/IEC ECC88s, or PCC88s. And for a rectifier, different versions of RGN1064s, or variants of the same spec Euro tubes having different pinouts... AZ1 and AZ11. Over decades, lots of materials, designs, makers, and vintages, there are a lot of flavors of these types. In Decware, all need adapters and none are the same spec as Decware is designed for. These rectifiers are rated for 4 volt/1.1amp, another story!

But in this setup, they are nicely resolving, dynamically complex, and spacious with less power/push... milder even than GZ32s, and still a little warm, but with more space and complexity, they are beautiful to me as a flexible and not domineering basis for the rest... importantly, their revelation and balances allow flexibility for the rest, while showing all clearly.

I think especially since all my stuff has been modified for more easy flow, I need less push here, but also I have never loved strong rectifiers, feeling like I needed to work around them as much a with them, and ending up with more open GZ32s and similar for many years before these.

Powerful rectifiers can sound really good here, but they make all aspects of the sound a little too much for me in sort of hifi "wow" ways... Very generally speaking, more concentration and focus from everything being pushed harder by more power, from low bass to high-highs...the amp circuits pushing caps and tubes more, at some point this over-emphasizes everything. Taken to extremes here, an aspect of excess consolidation and density throughout, this finally throws off spectral balances with excess bass weighting and darkness damaging bass focus, speed, and textures...  and more darkness leaking into the mids, along with excess consolidation in the mids, subtle and complex information is slowed, darkened, and hardened... subtle musical information that is critical to me.

Anyway, with tubes in the CSP3 more optimized to accommodate the 6CG7s, they were more compelling, but still a little off to me... a little unbalanced... most of the range still a little held-back, and the mids tending a little forward in that context. As I resolved these issues with gain tuning, this made me wonder what was up, and made me realize direct comparisons without playing more specifically with gains was defeating.

It also reminded me that 6SN7s with adapters, electronically kin to these, though more even spectrally, they too were initially a little more restrained and darkening/dulling in direct comparisons to my cleaner E88CC types. This could be different now, my room and system a lot more alive and flexible, but back then, I never loved 6SN7s in E88CC/ECC88 positions, though with tube and gain adjustments I was able to get great sound from them that others might have loved.



This morning, thinking about LiquidBlue looking at trying 6CA7s in a 6N1P position, I broke my commitment to avoid direct comparisons to more stock-like tubes after just using 6CG7s for quite a while. I did some quick tests using some old Cryoset 6N1Ps, and the Mullards, Valvos, and Siemens I had used so long for CSP3 power.

That was pretty revelatory in more ways than one... With the system set for 6CG7s, those tubes all showed well balanced spectrally, but sort of wildly clear and resolving, and strange to me being that clear, mostly in good ways... good extension, dynamic and spacious, and still complex enough to not be hard for the most part. Feeling too clear overall all though, especially with this 6N1P, the mids could get a little harder a little easier. This reminded me that I liked that tube in this position when I first got the CSP3, with nice complex and open warmth, but it was a little rigid for me in the mids to upper mids, and felt a little truncated in finer detail... And even with this very open setting, though less, these qualities still showed some for me. The system, much faster and more resolving than those days, I felt like I could probably integrate the tube now, but usually with these exciting initial impressions, with known issues still hovering in the background, if close, I can solve some of that and make the tube sound pretty great.... but they don't tend to stay in, sounding good to me in most ways... but other tubes fitting more naturally and comfortably.



Wondering if 6CG7s might end up this way for me... I was thinking my next exploration should be more articulate gain tuning for the tube specifically. Having backed pre stage gains off a little while exploring the 6N1P some this morning, that gave me a good start I think.

To test the theory of refining gains more systematically compared to my usual spontaneous ways, I started with the warmer/fuller Sylvainia labeled 6CG7 in the CSP3, and working on the CSP3 gains. All else was a little milder balance of pre stage gains I had been using with the slightly more open sounding Emersons, relaxed some playing with the 6N1Ps ... the ZBIT pretty strong, between 3 and 4 o'clock, ZRock not far above unity with a nicely open 12AU7 (not a pumped up variant). From there, I adjusted the CSP3 gains to be a little warm without bass becoming muddled and creating mid masking, which was not so easy with this particular warm leaning tube... at the same time I was listening for livening up the signal as much as I could with natural density, dynamics and lucidity, while being careful to not overdo darkness or density that would consolidation and damaging complexity, openness, lucidity. In initial experiments, this was easiest by turning down the CSP3 input tube attenuators from 8 to 7 and the main gain pretty high, around 3 o'clock here...

Generally speaking, my pre stage gains turned up just so increase the signal power, ideally so that all is enhanced without imbalances. Taken too far, the denser/fuller/darker parts become domineering, at some point especially messing up the lower end of spectral balances. So in this system, where I have worked so hard on balances that allow most recordings to be beautiful in most balances (with gain tuning anyway), I do not need more warmth. Still, within reason, I can love a little more if I can amp up gains for lively dynamic lucidity without getting too dark. So I played a little with pre stages again, and things got even better.

This particular 6CG7 still showing some very minor darkish veil issues that by now I was pretty sensitive to, and my pre stages seeming to be tuned as far as I could without imbalances, I raised the amp gain a little, making the whole signal stronger/more defined, and it seemed to even up the sound while filling the sound space more...

Then, having established a new baseline of gains relationships, I refined other pre-stage gains further, tuning for roughly the same balances and information, while trying for more lucidity and dynamic complexity.

Finally, after all that, I thought I was seeking good balances, which is true. But now I am guessing that I have been more or less trying to give this tube the right juice to perform more optimally, while also trying to more fully resolve its warmth and bass weighting. Still warm, but dynamic, revealing, and pretty balanced throughout, the original anomalies are not really showing from recordings so far. Now I find these particular Sylvanias pretty beautiful, if a little warm for my tastes. And really, these tubes look new, so might get good for me with 50 more hours or so.

Then, warming up the Emersons again, with these same settings, still warm, but more open, dynamic, spatially alive and free... the sound is quite beautiful for me... a happy place of warmth that is alive and fresh. This could all change with more recordings showing imbalances I am not hearing now, but I have been using these tubes long enough that I think I am doing well toward optimizing the tube to my needs in this system.

So I have a better tube baseline and gain balances from which to tune for different 6CG7s and recordings. The gain balances are basically turning down pre-stages a little with compelling balances from how they work together, while giving more gain to the more neutral amp.



Just thinking out loud, but this tube is different enough from good E88CCs, that not doing direct comparisons, it was easier for me to find more complete balances and pull a deeper potential for beauty from the 6CG7.

I am thinking soundwise, this process may have been a lot about optimizing things for the different electronic draw of these tubes, or 6SN7s. And not having tested them today, from memory I think 6SN7s in these E88CC positions are different enough sonically from 6CG7s, that tuning around differences between 6CG7s and 6SN7s with tubes and gains could likely help balance differences from direct comparisons between them...not making the the same, but perhaps making them both "good."



I imagine this all may be a big deal for me in part because I have come to relatively hair splitting balances here, having worked on this system and room so long, and in so many ways. And so much of it has been adjusting the many little seeming things like resistors, caps, wires, connectors.... rather than buying new components and cables and all to adjust the system/room. Whether front end components, pre stages or amps, power, cables, speakers....   Changes have mostly been a progression of refinements of what was already there. So over time it seems I have gotten to know the sound in most of its complexities pretty intimately as I experience and tune the whole. Literally hundreds of little refinements over many years, all that stayed mattered in terms of refinement of the balances of balances.

Related, adapting to new things that change the balances can mess with the pretty refined balances already in place. But as my system refines, so do the tools I use to adjust balances day to day...  component settings and tubes mostly, but also power adjustments and cables...  So I can usually muddle through integrating new things that show signs of possibly improving the whole.

Lately I still see the vast balances that make the sound experience as complex in ways. But at the same time, I am finding it is getting pretty straight forward, the balances of balances powerful teachers. At this point, with complex spectral balances that are relatively neutral, not off in any notable ways, along with related speed balances and harmonic/textural/spatial complexity that balance across these spectral balances... These provide a foundation from which more open or warm, forward or more relaxed, more space and fine detail or more density, etc, can be tuned, while defining limits before things get off.

Then the soundstage is a final arbitrator, showing subtle issues by how the soundstage presents. When some things are little off, it can be really wide and less deep, usually from a little too much density here, and little too little harmonic complexity and space... And adjusting that, it can become closer to as deep as it is wide, while making day to day listening from all over the house more beautiful.

So the balances and how they play in the whole finally tell me what to try to refine, in ways making it a "self healing" process... Within the ranges that work well here, if something is a little off, it tends to finally show pretty clearly with attention, and I can usually find ways to solve it.

That said, I am always learning, and finding new ways to improve as my baseline becomes more real, so the beat goes on... like this exploration of trying to articulate how to integrate 6CG7s with grace here.



Related, this being a highly modified setup, in line with the usual variations we all experience in our varying system/rooms, settings and effects I arrived at here will very likely vary. But I imagine these principles should translate if needed.

Will- Many thanks for the 6GC7 3 plate update and your detailed write up.
Very informative and helpful.  Your description on how the 6GC7 sound is very similar to my short use with mine.   Once I changed the rectifiers and adjusted gain they improved.  Very nice sounding now.  Need more time to see where they land.

Lon, thanks again for all of your tube observations. Have you tried a pair of E180CC/7062 tubes in the 6922 positions?

You are welcome Hearafter. I just noticed I have a few 6CG7s in the gang PO boxes down the road where I get mail. One pair is a "NOS GE 6CG7 1960 Long Gray Triple Plates (center Shield) Halo Getters" that has some different construction from the Westinghouses I mentioned. I look forward to hearing and comparing.

That is funny Lon... going to change the gains on the CSP that is no longer there!

Yes. my knowledge and understanding as well. I think the 6085 are special tubes, and I like them best in 6V mode.

CAJames wrote on 07/10/24 at 15:39:43:

12SN7 would have to be run with a base to at least convert to 9 pin. These 6085 work without a converter (in part as they are 9 pin).

Well I put more hours on the RCA black plate yesterday and this morning. Then I put the 6085 back in.

No contest--I prefer the 6085 for tone and texture. I'll keep using these until I can try some Amperex 6CG7 which are not easy to find inexpensively and I suspect will be significantly different to warrant trying.

Yeah, not easy, and I'm now in no hurry. Looking for Holland made if possible, even more difficult. At least I've satisfied my curiosity about this tube type for now.

Glad the early returns on the RCAs are positive. Since you're half way there you might as well get another clear top to complete the pair.

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Yes. My (non-Decware) preamp uses a pair of 6SN7s for input. The 6SN7 is a dual triode, and the good ones have gotten pricey. But there are many single triodes that are equivalent to half a 6SN7 so a pair of them (with adapter) can replace one 6SN7 and that is what I've been hoarding collecting. So I have done mix-n-match single triodes, with good success. I compare it to blended Scotch vs. a single-malt matched quad. YMMV.

But I haven't done it in my Decware amps.

Will, thank you for the detailed post. I read through it again last night more carefully. Lots of great information in there! Your impressions are helpful to get a baseline to work with. Lon, yours as well. I have a pair of RCA black plates and a pair of RCA 3 gray plate tubes on the way to me and looking forward to trying them out.

So I figured for completeness I ought to go back and re-listen to the 6CG7s in my current setup. FTR non-Decware pre with Super Tube Rectifier and UFO25s with Cossor 53KU rectifiers, Mullard EL822 power tubes, Sylvania JAN 0B3 in back Hytron JAN 0C3 in front.

I listened to the RCA Clear tops and Black plates and, neither of them sounded like I remember. The clear tops were like Lon described: bright (esp. on high piano notes) and sibilant. The black plates sounded good: big and sweet and airy, but lacking a little in dynamics and transparency compared to my favorites. I suspect different rectifiers and front VR tubes might change the equation more in favor of the 6CG7, because I remember them sounding better early on with the UFO25s, and much better with the UFOs. But I lost interest in the experiment and am going back to my Tesla 6CC42s.

Spent more time with the RCA 6CG7 Blackplates with center shields in my Torii Jr amp.  These are really nice sounding tubes you guys recommended.  I would not have come up with trying these in my Torri Jr. Thank You!!  They are paired with 4 Mullard EL34 xf2, 2 RCA VR150/OD3, STR-104 super rectifier. The one thing I did notice is these tubes sound better with more gain.  To get optimum SQ I have to play them louder than 6922/7308 variants.  Not an ideal tube at low volume.  They become soft/veiled, less detail and less dynamics/bass.  But with the right amount of gain/volume these tubes are excellent and keepers.

Liquidblue-  Interesting results with your gain adjustments.   Just a different way to get the same results. I am using the 6CG7’s as input tubes in my Torii Jr. On my system I get better SQ results turning down my amp volume while increasing my preamp gain slightly and increasing the preamp volume control.  This appears to give the 6CG7 input tubes more current while the preamp provides more gain and the amp output tubes do less of the load.  
I find it very interesting how all our systems and components set up's vary and need adjusting in different ways.
Next up is rolling some VR tubes to see what kind of an impact that makes on these tubes.

Hey Hearafter. I actually did initially reduce the amps gain a little, when I boosted the output gain on the preamp, to compensate. Failed to mention that. I adjusted the master volume on the preamp for late night listening. Glad you found your tube synergy. I actually feel like I found mine this evening, as well.

Earlier, I swapped out the RCA 5z3 for a Cryotone 5U4G, which sounded similar, but good. I just swapped it for a Mazda GZ32 and WOW! Everything is just so right, right now. Goosebump city. That little bit of extra voltage did the trick. Different methods, similar results like you said. Think I’m going to sit with this combo for a bit. Don’t see need to change anything right now.