Dennis Had Inspire Amps

[Breakdown7]

I also have a Russian Tung-Sol 6SN7. It came in my PSE, but I immediately pulled it out and never gave it a chance due to the sound you described above. Maybe I should? I have been running a Sylvania 6SN7GT, but I'm gonna try Westinghouse black plate 6SN7 next.

[Bombadil]

I have 4 various vintage Sylvania 6SN7. I like all of them better than the new Tung-sol.

(Edit) I just popped the Tung-sol out, after 6 hours. I listened to music for a couple of hours, let it run for another 3+ hours, then listened again for 30 minutes. I just couldn't enjoy the sound. I had to get it off! Put in one of the Sylvania's and there was an appreciable improvement. Eventually I'll get back to my Westinghouse but I like to make the rounds now and then. Give many tubes a chance to feel the power. Reaffirm earlier findings.

[Bombadil]

The most overrated 6SN7, IMO, is the RCA (and others of the same ilk) red base 5692. I have one and it sounds okay, but nothing special. When I did my shoot-out of 16 6SN7s, I ranked it #6, which is certainly decent. But that placed it behind 5 other inexpensive tubes.

There's really no reason for this tube to be so expensive. I've seen them selling for over $200. There's a mythic reputation of it. Built in the "Golden Age" of tubes. Heavy duty military designed to run for 10,000 hours (which is true). But one has to look more closely at it. It was rated for 10,000 hours because RCA lowered the specs considerably, where a 6SN7 is rated to run at 450V and has a 5W plate dissipation, the 5692 was derated to 275V and 1.75W. At those lower voltages it lasted much longer. When run at standard 6SN7 values in an amp, it doesn't last any longer than a regular 6SN7.

It is built to more rugged standards with more bracing and less vibration. But there's no reason for that to make it sound better in an audio application.

Right now I'm running a 1950s Sylvania black plate 6SN7gtb which has a "chrome dome" covering the top 1/3rd of the tube. Not one of the classic "true" chrome domes, but a nice tube. One can get these in used but very good condition for around $15-$20. To my ears it is better than the red base 5692.

[nhparrot]

I have tried a number of input tubes in my Inspire including:
NOS Sylvania 6BX7
Admiral 6SN7GT
Zalytron 6SL7GT
Tung-Sol 6SU7GTY
Raytheon JAN-CRP-6SN7GT VT-231
NIB Full Music 6SL7
NOS Sylvania 6SL7GT VT229
RCA JAN CRC 6SN7GT
RCA 6SN7GT VT-231
NOS Tung-Sol VT-229/6SL7GT
NIB PSVane CV181
NOS Tung-Sol 6BX7GT
Ken-Rad JAN-CKR-6SN7GT VT-231
Amperex 6SN7GTB

Of all the tubes I have tried my top 5 are:
PSVane CV181
Tung-Sol 6SU7GTY
Raytheon JAN-CRP-6SN7GT VT-231
Zalytron 6SL7GT
Sylvania 6SL7GT VT229

[Bombadil]

Oh, that reminds me of the VT designation. It doesn't mean anything for a tube to have a VT-229 or VT-231 label. The military had a inventory system based upon VT numbers. So they asked tube manufacturers to print those numbers on the tubes. Manufacturers complied. They did not change their tubes in anyway. So a Sylvania 6SL7GT is exactly the same as a Sylvania VT-229. Some tube sellers like to portray the VT tubes as some kind of improved military tube.

This doesn't mean the VT-series tubes are inferior or lesser in anyway. Some of them are great tubes.

As to 6SN7 vs 6SL7, to my ears and in my system, I cannot stand any 6SL7 in my Inspire amp. Makes my system way too harsh and bright. My system has a very detailed sound to begin with and using a 6SL7 pushes it way over the line. Perhaps I should give a listen to using a 6SL7 with my Spica speakers, which are more laid back.

[Breakdown7]

I also have a nice pair of Sylvania 6SL7GT tubes, but don't care for them in my Inspire gear. Too clinical, bright and shrill for my system. Granted, my speakers are very revealing and don't have a warm coloration to them. If I were running some older vintage speakers that were rounded off sonically, maybe the 6SL7's would be just the ticket.

I'm experimenting with Westinghouse 6SN7 black plate and RCA grey glass VT-231 tubes at the moment. I hear the Sylvania chrome domes as being very neutral/transparent with the Westinghouse having the slightest bit of warm coloration. The RCA VT-231 are warm, rich and velvet smooth.

[Bombadil]

It may be that my amp isn't a good match for the 6SL7. As I've noted before, my amp runs tubes hard, at their maximums. That's with a 6SN7. As a 6SL7 has considerably more gain (over 3X), it may be that it pushes my output tubes too hard.

The two tubes aren't really compatible. There are several differences. If a circuit is optimized for a 6SN7 then it really isn't optimal for a 6SL7. Technically they can work in each other's sockets.

[Analog Addict]

In Dennis' gear, that generalization isn't always valid. Many of his pre amps/amps will take either 6SN7/6SL7 and sometimes even 6BX7. Best way to tell is to ask....

[Comzee]

I really like the tung-sol 6f8g black round plate. You'll need an adapter tho.

[BearCityUSA]

Originally Posted by Comzee

I really like the tung-sol 6f8g black round plate. You'll need an adapter tho.

You got any pictures of that?
I’ll bit it looks spectacular.