Dennis Had Inspire Amps

[Comzee]

Originally Posted by Musica Amantem

Could I ask if anyone has had good results using a 6SL7 (or equivalent) in their Inspire amp, and if so, what the complement was and the type of amp (Pentode or Triode configuration)?

I have the fire-bottle SE HO, not sure if it's pentode or triode strapped, guess somebody can let me know.

The only 6sl7 I tried was fullmusic, it was decent.
It's sweeter treble, but a bit less mids and doesn't have the linear full range sound like my 6sn7's.

I find brand and design go further in terms of overall sound quality, than model types (6sn7 vs 6sl7 vs 6bl7 etc..)

[FloridaBoy]

Originally Posted by Musica Amantem

My Inspire came originally from Dennis with a current production Tung-Sol 6SL7. When I replaced that with a NOS 6SN7, with a slight gain loss, the sound improved tangibly. I know this does not mean the 6SL7 cannot make this amp sing, it probably will depend on the tube complement set.

Could I ask if anyone has had good results using a 6SL7 (or equivalent) in their Inspire amp, and if so, what the complement was and the type of amp (Pentode or Triode configuration)?

I have on hand a JAN Phillips 5691 (6SL7-equivalent) and several other Sylvania and GE 6SL7's, and will be trying those for the first time since I replaced the original Tung-Sol I sid not care much for. The output tube is going to be the GL KT-77.

I will be also trying a Shu Guang 6N8PJ, which is a 6SN7 variant, and a Radiotron VT-231 (6SN7). Thanks for any feedback on 6SL7 results!

6SL7's work just fine.

[Musica Amantem]

Interesting to confirm yet another opinion on better results with the 6SN7, overall. Although I agree with your take on brands and design features being leading factors, IMO there seems to be a pattern of better affinity with the 6SN7, or at least it being easier to accomodate in the Inspire sound-making process over the 6SL7, as the former seems less intruding, maybe due to its lower gain.

Curiously, I found yet another good 6SN7 for the GL KT-77 in the Radiotron VT-231 (6SN7 GT), so now I have three input tubes in synergy with this particular output tube. I need to try some 6SL7 just the same. Thanks for sharing your experience.

[FloridaBoy]

Originally Posted by Musica Amantem

Interesting to confirm yet another opinion on better results with the 6SN7, overall. Although I agree with your take on brands and design features being leading factors, IMO there seems to be a pattern of better affinity with the 6SN7, or at least it being easier to accomodate in the Inspire sound-making process over the 6SL7, as the former seems less intruding, maybe due to its lower gain.

Curiously, I found yet another good 6SN7 for the GL KT-77 in the Radiotron VT-231 (6SN7 GT), so now I have three input tubes in synergy with this particular output tube. I need to try some 6SL7 just the same. Thanks for sharing your experience.

Not a bad idea because 6SL7's are cheaper 6SN7's.

[Bombadil]

6SN7 has a mu of 20, draws 0.6A from the heater and is best used with around 8 to 10 ma of current.

6SL7 has a mu of 70, draws 0.3A and usually uses less than 1 ma of current.

In many amps one has to redesign the circuit to switch between the two. They are not considered to be direct equivalents. Dennis has said that he has designed his circuit to handle either, but switching one for the other will have an impact on the sound. Usually if an amp is designed to be linear with a 6SN7, it will measure differently if you use a 6SL7.

[Musica Amantem]

Originally Posted by Bombadil

6SN7 has a mu of 20, draws 0.6A from the heater and is best used with around 8 to 10 ma of current.

6SL7 has a mu of 70, draws 0.3A and usually uses less than 1 ma of current.

In many amps one has to redesign the circuit to switch between the two. They are not considered to be direct equivalents. Dennis has said that he has designed his circuit to handle either, but switching one for the other will have an impact on the sound. Usually if an amp is designed to be linear with a 6SN7, it will measure differently if you use a 6SL7.

Yes, I'm aware of those spec differences, but why did Dennis ship my brand new Triode-strapped HO KT-88 Inspire amp with a Tung-Sol 6SL7? Probably he wanted to compensate some for the power limitations of that Triode configuration. But, if someone asks for a Triode-strapped (old man's) amp, it is quite clear the objective is to get the best sound possible by accepting the corresponding tradeoffs involved (i.e., dynamics). So there may be some merits to the 6SL7, after all.

It won't take much effort to do another set of testing with 6SL7's (5691's) and find out which output tubes can work well with these.

[x3workshop]

Originally Posted by Musica Amantem

Yes, I'm aware of those spec differences, but why did Dennis shipped my brand new Triode-strapped HO KT-88 Inspire amp with a Tung-Sol 6SL7? Probably he wanted to compensate some for the power limitations of that Triode configuration. But, if someone asks for a Triode-strapped (old man's) amp, it is quite clear the objective is to get the best sound possible by accepting the corresponding tradeoffs involved (i.e., dynamics). So there may be some merits to the 6SL7, after all.

It won't take much effort to do another set of testing with 6SL7's (5691's) and find out which output tubes can work well with these.

I've used an RCA VT 229, as well as Sylvania, RCA, & TS 6SL7's with RCA 807's and Amperex EL34's and they worked very well for me when I was driving a small pair of a/d/s L300C's in my office as well as with a vintage pair of Desopren folded horns. It seemed to add a nice upper midrange w/those two setups.

I did not like it when running KT88 or KT120's and have been using a VT 231 and Sylvania 6SN7's for the last few months.

[Bombadil]

Originally Posted by Musica Amantem

Yes, I'm aware of those spec differences, but why did Dennis shipped my brand new Triode-strapped HO KT-88 Inspire amp with a Tung-Sol 6SL7? Probably he wanted to compensate some for the power limitations of that Triode configuration. .

Dennis is constantly making design changes to his amps. He may have tweaked the circuits a bit in that design to use a 6SL7. Just like he has tweaked other versions of these amps to use 6DJ8 drivers. Perhaps your triode-configured design needed the extra gain of the 6SL7. All I am saying is that these two tubes are different enough to make a significant difference in many amps, in some amps to the point of swapping one in for the other could make them unstable.

This is why tube sellers, such as The Tubestore, have different pages for 6SN7 & Equivalents, and 6SL7 & Equivalents.

[Musica Amantem]

Originally Posted by Bombadil

Dennis is constantly making design changes to his amps. He may have tweaked the circuits a bit in that design to use a 6SL7. Just like he has tweaked other versions of these amps to use 6DJ8 drivers. Perhaps your triode-configured designed needed the extra gain of the 6SL7. All I am saying is that these two tubes are different enough to make a significant difference in many amps, in some amps to the point of swapping one in for the other could make them unstable.

This is why tube sellers, such as The Tubestore, have different pages for 6SN7 & Equivalents, and 6SL7 & Equivalents.

Interesting. I may be in for further surprises, then, since my amp sings with the 6SN7's so far. To think it could even sound better with a 6SL7 is exciting. We'll see!

[FloridaBoy]

Originally Posted by Bombadil

Dennis is constantly making design changes to his amps. He may have tweaked the circuits a bit in that design to use a 6SL7. Just like he has tweaked other versions of these amps to use 6DJ8 drivers. Perhaps your triode-configured design needed the extra gain of the 6SL7. All I am saying is that these two tubes are different enough to make a significant difference in many amps, in some amps to the point of swapping one in for the other could make them unstable.

This is why tube sellers, such as The Tubestore, have different pages for 6SN7 & Equivalents, and 6SL7 & Equivalents.

They are different tubes but either can work in the amp I have. I recently got some Ken Rad 6CG8's. This tube is between a 6SL7 and 6SN7 and needs an adapter. It sounds very good and 2 NOS pairs with matched sections was $45 delivered.