6SN7GT VT231 TUBES

I'm using the Sylvania 6sn7 gtb tubes right now and love them. I actually bought several sets just to have backup. I also have a few sets of the Raytheon and Tung Sol 6sn7gt (not the oval mica). I think they are really close but slightly prefer the Sylvania. The Sylvania 6sn7 GT 3 hole Bad boys are a little bass heavy in my system but have great soundstage and some spooky holographic detail that I do love. I could certainly live with them.  I also tried the Ken Rad VT-231 clear glass but I have not found a set that wasn't microphonic unfortunately.  I'd love to try the oval mica TS VT-231 but those prices have just gotten too steep for me. Running $ 800.00 a pair etc. Wow!

I have heard that the military VT-231 designation is overblown and many of the standard 6sn7 GT or GTB from the same era sound no different. YMMV

Thomas,

I've read through your 6sn7 tube shootout many times. It's a great guide and has helped a lot in my selection. Any particular 6f8g tubes that you prefer?

Thanks,

Mark

All of them are pretty great, and the final choice is going to be very system & listener dependent. More often than not, I like Tung-Sol black glass round plate 6SN7 the best - if I had to pick one, that's it. Unfortunately, I've had the bad luck of heaters going out on a few of these. 

I prefer Sylvania (side getter) VT231 over RCA. Sylvanias in general (through the 1950s) are pretty cool with me. Next are Hytrons and Ken-Rads. And RCA last (but still nice). I haven't had the pleasure of trying the Raytheon VT231, but they look lovely! Heck, even the Russian issues (Electro Harmonix, Tung-Sol) can be good - they measure VERY strong in transconductance, and can sometimes be best-in-slot for driving lots of big KT tubes. 

What I found is that vintage 6SN7GT tubes are best suited for the input stages of power amps. In these slots, you're getting all of their sweet sound with none of the downsides. In preamps, these old tubes are going to have all kinds of noise / microphony issues. Even worse in phono stages. As an output stage tube in headphone amps (this was more popular circa 2000s head-fi), they are very weak compared to many other better alternatives. 

For preamp slots, it's best to stick to later GTA / GTB issues (lower noise & microphony), or modern Russia/China tubes which can be selected for very low noise (and matched tightly, to boot). 

6SN7 is a GREAT tube, but it's important to respect its proper role and limitations. 

@vintageadict 

RCA, Sylvania, Tungsol 6f8g are good.

But Tungsol seems to be overpriced due to hype.

Raytheon sounds more shapr and clear thus dependent on system and taste.

Thomas

Interesting that I mainly use the 6SN7 tube family in my preamp and have not experienced any noise or microphony issues with older tubes.  Just a couple outright failures.
My preferred 6F8G tubes are Raytheon with flat ladder plates (very hard to find).  Step up from the T plate version.  National Union round plates and RCA Gray Glass are also excellent.