Dennis Had Inspire Amps

[Bombadil]

Originally Posted by 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....

I know he says that, and it is true that both work. But you can't optimize a circuit for both. They are too different. You can optimize for one or the other, or for neither by splitting the difference.

The 6BX7 is not a direct substitute for either a 6SN7 or 6SL7. In some amps using this tube in a 6SN7 socket will cause the amp to oscillate. One can certainly design a circuit to prevent that, but it is still a questionable substitution in terms of its affect on the sound.

[Bombadil]

Originally Posted by Comzee

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

Now those are very close to a 6SN7, with the adapter. I've never even seen one.

[Bombadil]

I guess I would submit my own Inspire amp as an example of the 6SN7 vs 6SL7 issue. With a good 6SN7 my amp sounds fantastic. Beautiful natural open sound. I get drawn into the music, which can sound so lifelike.

But if I stick a 6SL7 in it, with which it seems compatible in terms of still being a stable amp, the sound becomes very forward and even shrill. Too much detail in the upper mids and highs. Within a few minutes, I get headaches from it. Can't stand to listen to it. The effect is anything but subtle.

It goes from beautiful to unlistenable by simply switching that tube. With a good 6SN7 the amp sounds like a $5000+ amp. With the 6SL7, well, I'd rather listen to my 30 year old Rotel RB-850 SS amp.

[Comzee]

Originally Posted by Bombadil

Now those are very close to a 6SN7, with the adapter. I've never even seen one.

They look like this, below:



Also, if anybody has a better ear to Dennis, it would be appreciated if you could ask him about making one of his newest universal fire-bottles for headphone use. I asked him a lot about it about 6 months back, and it never culminated to anything. I assume he has a lot on his plate and doesn't like taking custom jobs, not sure.

I know myself, and a few other audiophiles I know would love one of his universal fire-bottles for headphones use.

[Breakdown7]

Good info about the 6SL7's instead of 6SN7's. So whats you guys thoughts on using a 6BX7? I know Dennis says it is possible, but how does that change the sound?

[Bombadil]

To my ears, and in my system, the only tubes which sound good in the driver stage socket are 6SN7s and true equivalents - 5692, VT-231, 6H8C, a few others, including some "mislabeled" CV-181 from PSVANE and other Chinese manufacturers. A "true" CV-181 is not equivalent, but these guys made real 6SN7s and decided to label them as CV-181s. The Brimar CV1988 is equivalent to a 6SN7, however it tends to be very microphonic and thus not suitable in audio equipment. [NOTE: If a tube has both a JAN label and VT-231 label, then that's a military grade tube. But if there is only a VT-231 along with 6SN7GT, then that's simply a common tube with a military inventory number printed on it.]

Tubes which negatively affect the sound of my Inspire amp include 6SL7, 5691, VT-229, 6BX7, 6BL7, "real" CV-181, 6H9C, 6N9S, 6SU7, CV1985.

If you are interested in learning more about the 6SL7 and how it differs from a 6SN7, click on this link: http://vinylsavor.blogspot.com/2016/...onth-6sl7.html

[Tyson]

Can I play too? I'm super stoked to have picked up a pair of MB 12 Inspire Monoblocks, circa 2014:



I actually took the KT150s out before I turned it on and replaced them with some Gold Lion KT77s, as well as the 6SN7s with NOS GE 6SN7s and changed the rectifier tubes with Tung Sol 5u5g tubes.

These were all new tubes, so still running them in. But even with the tubes still fresh, I must say that this amp sounds remarkable. Right now it's displaced a TAL Korneff 45 SET amp I'd been using, and my poor Almarro 318b 20 watt SET amp sits in the corner looking lonely :

[Masterlu]

Tyson... Welcome to AA, from lurking mode.

[FloridaBoy]

Originally Posted by Breakdown7

Good info about the 6SL7's instead of 6SN7's. So whats you guys thoughts on using a 6BX7? I know Dennis says it is possible, but how does that change the sound?

If you already have a tube stash try it. I did but my ears, long term, like 6SN7's.

[Comzee]

Originally Posted by Bombadil

Tubes which negatively affect the sound of my Inspire amp include 6SL7, 5691, VT-229, 6BX7, 6BL7, "real" CV-181, 6H9C, 6N9S, 6SU7, CV1985.

Originally Posted by FloridaBoy

If you already have a tube stash try it. I did but my ears, long term, like 6SN7's.

I can thirdly agree with this. I own the kt88 fire-bottle. Tried most of the tubes Bombadil listed too. 6SN7 just sounds.. correct. At least in the design Dennis has implemented. Of course if you get something that's almost electrically identical to the 6sn7 like the 6f8g that works too.

Also a quick list of my personal favorites. I don't have one, because I'm a tube swapping machine. Each one gives me a specific sound for whatever I'm in the mood for any given day.
RCA red base 5692
Melz 5 hole plate 6sn7
Tung-Sol black round plate 6sn7
Psvane grey bottle cv181 (which is 6sn7)
Tung-Sol 6f8g (mentioned this just earlier)
Fivre 6sn7

Also, I can't overstate enough (in my opinion) how much rectifiers matter. Again same vain tho, nothings best, they just dramatically change up the sound, so I can mix and match to find really unique styles.
Favorites are:
GZ34 metal base (expensive, but legendary)
U52 (From England) (expensive, a pass for most people because of price, unless you're a crazy tube roller like me)
United Electronics 596 (was made for USAF, need an adapter, but crazy good)
RCA CRC 5r4 ST shaped dual bottom square getter
Type 80 tube (need an adapter, lighter bass, but awesome sound. It's what the 5y3 evolved from)