Sophia Electric 6SL7: Current Production vs NOS Tubes
Soon after getting the SE power tubes into my system, I ordered a 6SL7 from them. The 88’s are excellent, and I figured we should see how their pre tubes perform.
I have three other vintage 6SL7 types, and here I’m comparing two of those to the SE tube:
GE 6SL7 variant – I don’t have details on this one. I bought it used from another Head-Fi member.
Sylvania 6SL7GT – I bought this from Upscale Audio. A fairly expensive NOS tube, that is well regarded. This one I’ve used almost exclusively since I bought the Mogwai.
A shot of the Sylvania’s box – a military tube manufactured in 1944. I admit, the romance of vintage gear grips me at times. In the end, the desire to better understand the equipment, and for better sound drives my choices.
If you are new to tube gear – I’ve only returned to higher end audio in the past several years – then, I recommend an exercise like this if you can get a hold of the tubes. The perspective gained, even with a simple listening test, is valuable. In fact, it’s necessary in order to understand what you are hearing. Many of you can’t or don’t want to put time into this – so, then this is for you. Hope this provides some insight.
You’ll likely find over time that there are no absolutes, and that each component or tube simply sounds different (so long as they are of similar quality/build) and what’s best for you may even change at times. For example, I have preferred a slightly more mid-forward tube for their tone and texture. This has changed some over time, and the SE KT88’s more linear and balanced performance is checking all my boxes today. Listening to as many amps/tubes as possible is the best way to figure out what you want to hear.
A dedicated Win10 machine/Fidelizer Pro/Tidal/Roonserver(headless)/Android and PC Roon remotes/Schiit Yggdrasil/ampsandsound Mogwai/Audioquest Nighthawks. I use Anti-cable interconnects (analog and usb) and a Double Helix Molecule SE headphone cable. All gear powered by a PS Audio Power Plant Premier.
I used a playlist I created a while back for more critical listening. Of course, it’s music I like, but also selected because I know the songs/recordings very well and they represent various levels of recording quality.
After swapping out the three tubes – beginning with the Sylvania – and listening for several hours, I selected three tunes for a more immediate comparison. I listened to each track three times and took notes. I powered the amp down and quickly swapped the pre tube and listened to the track again.
Sparklehorse – Sea of Teeth
Fiona Apple – Valentine
Joshua Redman – Act Natural (live)
The following notes came out of this session. Note that generally these differences are subtle – not huge shifts in sound quality.
Overall character is a shade darker than the other two. It has the slightest mid bloom, so sounds closer and more closed. Voices do sound very nice, which makes sense since it was likely built for military/communications use. The shimmer and brilliance frequencies are slightly forward. The stage width is inside the headphones. Again, the space is shadier, shallower and with a lower ceiling. Bass notes are less defined, and I’m getting a bit more mid-bass. Cymbals are fairly natural. Acoustic guitar has more gut – less neck. I do love this tube.
This is a leaner sounding tube. The stage is lifted slightly above the Sylvania. Maybe forward leaning treble. Stage width is inside the headphones. Slightly more illumination here due to overall brighter character than the Sylvania. More attack in the bass freqs – chest thumping kick drum, though less presence below 50hz. Snare drum sounds more papery and with less body. The vocals are drier and more whispy – we lose some throatiness. Hihats are more tick/tack, and with less body. Acoustic guitar has more fret and string attack.
Sophia Electric 6SL7:
First, a couple comments on build quality: a tighter fit in the tube socket. With the heavy glass the tube feels more solidly built. The SE may have a touch more gain (Note: I left the volume in the same position for the entire session). Overall, remarkably more linear and balanced. Similar to the KT88, this tube appears to meet Sophia Electric’s claim of low distortion, dimensional, open imaging and dynamic drive. They deliver more natural tone and timbre. The stage width is slightly wider than the others.I can hear more of the recorded space. Bass reaches lower, and I can better see the shape of the kick drum. I’m getting the whole snare drum, and not just the batter side. All of this adds up to a more real sound, as I imagine it. And while it is more open and illuminated, it’s not dry sounding. Very nicely balanced.
So, the SE 6SL7 outperforms my other pre tubes in the Mogwai. At US$100, they aren’t cheap, but are less than some NOS equivalents. Again, it’s great to find current production tubes that can match the best of the vintage selections. As time goes on, those NOS tubes will disappear, and become even more expensive.