Dennis Had Inspire Amps

[Bombadil]

Originally Posted by Analog Addict

I don't know if it's been commented on before, but logically, Dennis is an amp designer, not a tube collector. In general, he doesn't care if that expensive set of NOS Tung Sol Black Plate 6550s only last 2000 hours instead of 5000 hours. Instead he is looking to squeeze maximum performance out of the tubes so that the amps perform to the max.

This is good for me. I've never dropped big bucks on a rare NOS tube. Have been able to pick up some decent vintage tubes at reasonable prices. I have 11 matched pairs of various EL84 tubes. That should hold me a while, even if I don't get maximum tube life.

Burn baby Burn!

[FloridaBoy]

Originally Posted by guitardave

Yes, I have had if for about a week or so. Very nice amp. I am still burning it in, but currently using a 5u4 with 6sn7, a pair of KT 88's, and a pair of Pope 6v6's. Very nice combination! I am driving it with an Audionotekits Mentor preamp.
The amp has a nice "live" sound. Very open, detailed, and nuanced.

Congrats Dave! The ability to mix the power tubes is very cool. So is your preamp.

[Bombadil]

I remember reading that the higher output KT-88 SE amp could run at 10 watts with KT-66 tubes, 12 watts with KT-88, and 14 watts with KT-120 tubes.

Later Dennis introduced his High Output KT-88, advertising that it could produce 17 watts with KT-88s and that it had 20 watt output transformers. And he claims in his eBay description of it that the power transformer could run 4 of these amps.

Does anyone know if this second amp can run KT120 tubes? I can't recall ever seeing any mention of this. Or for that matter, KT150 tubes? Two years ago there was a discussion on this board about Dennis' claims that his KT88 amp could safely run KT150s.

[guitardave]

Yes, I had one of those amps and put KT150's in it. Sounded great.
I really like that tube. I am thinking I should try a quartet of them in my PSE...

[FloridaBoy]

Originally Posted by Bombadil

I remember reading that the higher output KT-88 SE amp could run at 10 watts with KT-66 tubes, 12 watts with KT-88, and 14 watts with KT-120 tubes.

Later Dennis introduced his High Output KT-88, advertising that it could produce 17 watts with KT-88s and that it had 20 watt output transformers. And he claims in his eBay description of it that the power transformer could run 4 of these amps.

Does anyone know if this second amp can run KT120 tubes? I can't recall ever seeing any mention of this. Or for that matter, KT150 tubes? Two years ago there was a discussion on this board about Dennis' claims that his KT88 amp could safely run KT150s.

My amp has the 20 watt transformers bit it is single ended runs the output tubes in triode. 6V6's in this amp are about 5 watts. I tried KT150's and did not care for them. These amps can run many tubes. However, there will be two or three that *sound the best* to your ears. A few extra watts will not be noticed unless you have very efficient speakers. Power needs to double for the next 3db of output. I have Heresy III's, 99db on paper, and they work well. They have a complex crossover and I do not know how flat the impedance is. You can get by with less power if the speakers are less efficient but have flat impedance. I don't feel like I need a subwoofer or more power.

When I took my amp and pre to a friends house last year and connected them to his 104 db La Scalas there was a huge difference in the presentation. We were shocked at how life like the Pope 6V6's and 5Z3/5U4G sounded. We used one of his Treasure CV181's for the input tube.

Google 'speakers for low power tube amps'.

[FloridaBoy]

Originally Posted by guitardave

Yes, I had one of those amps and put KT150's in it. Sounded great.
I really like that tube. I am thinking I should try a quartet of them in my PSE...

The KT150 must work better in an amp that is not triode wired/strapped. It sounded good but was not my favorite. Could be my room.

[Bombadil]

Did Dennis wire your amp in triode by your request?

I have a European PP amp wired in triode, running a quad of Sylvania Fat Boy 6CA7s. Produces around 18-20 wpc. It sounds fabulous. Has Audio Note output transformers. It runs so cool, even after two hours of playing the OTs are barely warm.

[FloridaBoy]

Originally Posted by Bombadil

Did Dennis wire your amp in triode by your request?

I have a European PP amp wired in triode, running a quad of Sylvania Fat Boy 6CA7s. Produces around 18-20 wpc. It sounds fabulous. Has Audio Note output transformers. It runs so cool, even after two hours of playing the OTs are barely warm.

No, he just built it that way. I believe a switch could be added to allow it to be simply run single ended. I may have that done someday but I don't feel that I need to. I'm done chasing my tail in audio.

[Analog Addict]

Originally Posted by FloridaBoy

My amp has the 20 watt transformers bit it is single ended runs the output tubes in triode. 6V6's in this amp are about 5 watts. I tried KT150's and did not care for them. These amps can run many tubes. However, there will be two or three that *sound the best* to your ears. A few extra watts will not be noticed unless you have very efficient speakers. Power needs to double for the next 3db of output. I have Heresy III's, 99db on paper, and they work well. They have a complex crossover and I do not know how flat the impedance is. You can get by with less power if the speakers are less efficient but have flat impedance. I don't feel like I need a subwoofer or more power.

When I took my amp and pre to a friends house last year and connected them to his 104 db La Scalas there was a huge difference in the presentation. We were shocked at how life like the Pope 6V6's and 5Z3/5U4G sounded. We used one of his Treasure CV181's for the input tube.

Google 'speakers for low power tube amps'.

In general, Dennis has not been a huge fan of the KT-150s. And a suggestion for you from me and Dennis. If you try your amp with the La Scalas again, try using a 5Y3G rectifier.....

[Musica Amantem]

Originally Posted by Analog Addict

In general, Dennis has not been a huge fan of the KT-150s. And a suggestion for you from me and Dennis. If you try your amp with the La Scalas again, try using a 5Y3G rectifier.....

Would not it be even better to use one of the NOS 6V6 G ST (1940's shouldered) types along with either the 80 (4 Pin) or the 5Y3 G/GT (Octal 80)? I know I would try that first with such a high sensitivity speaker. In my setup, with 98 dB's, the 80 comes short to boost the G ST (which in another amp fares much better through a 12AT7), so it's not the tube, is the combination plus the lower sensitivity, I believe. But once the G ST sings ... It is a dream!