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I have still been trying 6SN7 mostly in the CSP3 output position, but shifted to the Torii yesterday to see what I could do.
Especially in my Torii, the 6SN7 is so different from our more typical 9 pin tubes, to get a similar tonal balance, while opening the mids enough to pull their lively potential, I think the 6SN7 is the most difficult tube to adjust of any I have tried. Yet I continue because of its compelling qualities once fine tuned.
With those I have, some pretty definitely true NOS, 25 hours or so is needed to start to open up, and more like 50 or more to really start to hear them.
I don't think I would quite call the mids lush either, probably more calling them richly complex...clear, defined, with good textures and spacial information once tuned. That said my 51 smoked glass RCA 6SN7-GTs, when opened up with other tubes, have what I think of as classic warmth.... darkish, while still having good detail and spacial information. Also being a little slow, I guess one could tune it to sound "lush" with the right supporting tubes.
Here, if used plug-and-play in the Torii, some more than others, the 6SN7s are so powerful sounding, and balanced toward bass, they are overstated, dark, and thick.
Soundstage-wise, once tuned to compensate for there powered up nature, they have a nice stage, but about the same as 9 pin tubes I prefer, some tube sets a little better than others with either type.
Still running into variations of the same issues in my system as with the 1st 6SN7 I tried, with 4 pairs now, I can call my difficulties with it tube type related. In the Torii, and to a lesser degree in the CSP3 output, unless very carefully compensated for, they are notably too bold, and balancing toward dark especially when averaged across recordings. So to really hear what the tube can do, I need to open them up spectrally and relax them with other tubes.
Reducing power, bass and thickness in the balance in a just-so way is easier for me to get using the Torii, it having VRs in the blend. But I need to pay attention to both the Torii and CSP3 to get the magic, and especially in the Torii, each 6SN7 seems to need a little different adjustment to get the magic across most recordings. My CSP3 outputs utilize them really well and much more easily.
The complimentary Torii tube sets I like best so far are sort of predictable in some respects (working mostly with milder VRs and rectifiers), but still a challenge to open the 6SN7 just right across recordings while creating tonal beauty, great fine detail and space, and without losing too much bass power.
Two base-line Torii sets using variations on the Voltage Regulators to reduce power:
[Torii VRs had been confusing to me until I noticed O_3 types cut more voltage as the letters go up. So an OB3 reduces voltage to the power tubes more than an OA3, relaxing the tubes they are filtering some. Whereas, the little VRs are the opposite. OC2 cut the voltage least, the input tubes left bolder, and OA2s, cut voltage more, relaxing/opening the inputs.]
This set is a pretty good base here when using 6SN7s in the Torii inputs, focussed on toning down the inputs more:
AZ1 ST-shaped mesh plate rectifiers
OB3
Hytron OA2
TubeStore Preferred 6L6GC
Normal inputs when using the 6SN7s in the CSP3 output are:
Heerlen made, early 60s ECC189s
With voltage reductions being a little less, and reduced in the opposite way (none for inputs, and more for power tubes), I like this set a little more just now for using the 6SN7s in the CSP3 outputs:
AZ1
OC3 - mid-40s Hytron
75C1 (OC2)
TubeStore Preferred 6L6GC
Heerlen made, early 60s ECC189s
The first three tubes open up the sound compared to more stock-like tube sets. Finding stock Torii sets overstated (in my system/room anyway) I usually use well balanced but less forceful AZ1/RGN1064 rectifiers or similar, OB3, 75C1 (euro OC2), and ECC... or PCC... inputs rather than E88CC, so my sound is already more open and less bold than using stock OA3, OC2, and new Chinese 274Bs or similar. AZ1/RGN1064 being 4 volts, I am not sure how they would work in all amps, but in my Torii and CSP3, they seem to work well over the last several years. The sound is nicely balanced, spacious with warmth, and complex, but less intense than many 5 volt, higher powered rectifiers.
The TubeStore Preferred 6L6GC might be described as a little more powerful feeling version of an American made 807. Or maybe as a more nuanced and complex sounding Tungsol 7027A. I am guessing the heavier construction of Tungsols contributes a lot of the Tungsol power tube tendency toward solidity and less textural complexity. Though I have liked using the 7027A, I prefer the nuance and fine information complexity of this 6L6GC.
To test 6SN7 tubes in the Torii, in the CSP3, I used the following relatively low key, but quite clear, open, slightly warm and solid set:
AZ1 globe mesh plate
Siemens E88CC with hallow getters outputs
Siemens E288CC red label input
The Siemens E88CC and E288CC, and OC3 and OA2s almost never get used used here, each being too powerfully articulating and opening for me in general. But this clarity is needed for these 6SN7s in my setup.
With these baselines, all my 6SN7s sound different, but these clearer, less intense tube sets allow the 6SN7s to be closer to what I consider their fuller potential.... opened enough to have better balance across more recordings, bringing out more mid openness, while still being bold, but not bold enough to sound unnatural.
Even so, in the Torii, with my gains normally set, all these tend to be too warm for my tastes, but pretty fun to listen to, with tight enough and deep/full enough bass to sound pretty real.
When not testing, having two pre gain/voltage adjusters before the Torii, I can tune for more or less bass, weight and intensity depending on recordings.
I tested these as Torii inputs leaving gains set the same, and using the same lower key support tubes:
- 51 clear glass RCA GTA with two side getters, silver letters: Thinking it is still a little green, I can't compare it conclusively. But now, it has a nice balance, a little warm for me with this setting, but relatively revealing and fast, smooth and solid. It is still too dark on darker recordings, full/thickness leaking upwards, masking and slowing the sound, especially mids down. But on more neutrally balanced ones, it can be beautiful. Just now, this tube is a little quieter (dBs) and less complex than the others. But in this quickish test it is nice, and if I am right about burnin, I look forward to more time on it.
***BUT, another wild card came up when listening louder! Similarly to having always gotten early distortion using 6N1Ps in my Torii MKIV, I get less with these, but still! When loud, distortions can subtly show up in many areas of sound, but they are especially noticeable on fuller recordings with a lot of harmonic information, like harder notes of woman's voices, Ralph Towner's guitar, hard piano notes, or solo violin! More on this below...
- 55 clear glass RCA GT with offset plates and bottom D/horseshoe getter, silver letters: On more balanced recordings, similar balance as above, but louder, faster, and more articulate, more spacious and textured than the '51 with side getters. With well balanced recordings, this tube is spacious and revealing while being quite complex. BUT, with darker material, leaving the pres set the same, both of these similar sounding RCAs are still dark and veiled, probably needing additional tube tuning to work across recordings, at least for me.
***BUT, with louder play, this one slides into early distortion too!
- 51 Smoke glass RCA GT, sliver letters: when recordings are not dark, this tube gives an unusually good "warmth." Here it has the power and articulation to push quite good detail, complexity, and ambient information through its darkish basis. And its slightly slow leading edges support a pleasant smoothness. Though probably a little rolled off way up, on balanced recordings they reveal detail and associated ambient information really well..... But on a little darker recordings, even though it does warmth well, it sounds pretty unnatural to me without further tube tuning. Though the smoked glass uses what looks like similar construction as the above tube, I did not notice as much tendency to distortion when playing this tube louder in the Torii, but it is still there.
- Chrome top Sylvania GTB, halo top getter, green letters, guessing 60s: A little slow on leading edges, but with quite nice dynamics otherwise, it is open but with a more solid and articulate mid body than the others. Good spaciousness contrasts this body nicely, creating quite good complexity and ambient information. Though just a little rolled off way up, here, I like this midrange for its slightly full and solid, and dynamic character, while still being pretty complex. The complexity is weighted more toward ambient information than textures, but to me, not excessively.
Loud, this one has subtler early distortion similar to the smoked glass.
For my preferences, especially for all the RCAs, but for all, I would have to further tune my tube sets to accommodate them as Torii inputs if I wanted excellence across recordings, which I do!
*** On distortion. Move the same tubes to the CSP3 outputs, they sound notably more complete and balanced, and no distortion problems. This might support my thought that they could be like 6N1Ps in my Torii. 6N1P always falling into early distortion, I think I recall Steve attributing this to some Toriis having a too low "knee" for the tube???....I think I recall it being associated with the higher draw the 6N1P has on the amp. But not clear on just what is up, as a minor test, I tried going from OA2, to OB2s, and then 75C1s for input VRs, to gradually up the voltage to the input tubes. Each step, the distortion improved a little, but it was not totally solved. And checking tube specs, the 6SN7 looks much closer to a 6N1P than 6922/E88CC variants.
If I really cared about 6N1P and these tubes as inputs, and if I am correct about the cause, I imagine Steve would tell me how to adjust resistors to solve this issue. But finally, after these tests, though much better than without compensation, for now I am ready to give up on 6SN7s in the Torii.
Difficulty getting optimal musical balances with this tube type in the Torii was a reason for my trying them in the CSP3 outputs earlier. And there they are still a little touchy in terms of bringing out their best across recordings, but used as OTL preamp "power" tubes, the pre seems to even up, open, articulate and increase clarity and dynamics from the 6SN7, just like it tends to do with other tubes. Once a good balance was found in the Torii to tone down the whole, and some tuning in the CSP3 for more clarity, so far the 6SN7 in the CSP3 outputs work very well across recordings.
The Torii tube set I like for this above, the base tube set in the CSP3 with 6SN7s as outputs is AZ1 (or some more open GZ32, or 5V4G fat bottles can work pretty well too), and the very open, linear and articulate Siemens red label E288CC for the input. With the E288CC I found I can use open, but pretty powerful tubes in the CSP3, getting a nice complex, spacious, punchy and open body with the CSP3 powered up a little and the Torii powered down. If a particular 6SN7 is too concentrated and closed, I so far use an AZ1 rectifier to reduce density and open space and textures. Or if a 6SN7 can take more power while remaining open and textured, not becoming too dense, a Sofia Aqua 274B is really good in initial tests.
So after a lot of trial and error, in my system, the 6SN7s are compelling but perhaps not worth the challenges in the Torii, nine-pin sets being more natural and balanced sounding there.
But in the CSP3 outputs, with the right supporting tubes in Torii and CSP3, the 6SN7 do not overwhelm the sound with their nature, rather being quite compelling and a very real option for changing up the sound in beautiful ways, balanced across the spectrum, and across recordings. All of the 6SN7s I got work well in this use, hearing their beauty once fine-tuned...
On the other hand, when I put back in favored 9 pin tube sets, I always relax. I miss aspects of the 6SN7 blend of solid body, mid clarity and smooth/articulate mid complexity for a while, but enjoy the slightly more relaxed sound from my 9 pin sets which are fast, revealing, complex, finely detailed, spacious and punchy...also inviting. I guess at this early learning phase if I could find it, I might love a tube somewhere between 6SN7 and 6922/E88CC variants. But I do like combining them using 9 pins in one component, and 6SN7 in the other quite a lot!
So Safe and HK. if you have been listening to the 6SN7, plug and play just changing an input, I agree, they need burnin to hear them, and my guess is that the 6SN7 may be just too intense/full in your setups too to hear fully what they are capable of. From your 1st impressions, I am thinking some level of adjusting VRs and rectifiers and/or other tubes to calm and open the whole might better reveal the 6SN7 potential there similarly to how it did here.
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6SN7 tube (Read 16633 times)
