Dennis Had Inspire Amps

[Bombadil]

I've spoken to multiple amp designers and tube dealers who are very high on some of the current production tubes. I've been told that this is sort of a second Golden Age of tubes. Gold Lion KT77s and KT88s, Tung-Sol KT120, EH 6CA7s (at a bargain price), the recently discontinued SED Winged C 6L6GC, some of the PSVANE tubes, and more, have been positively compared to classic NOS tubes. Even some of the lower priced tubes, like Sovtek EL84s and Tung-Sol EL34B have fans. And the JJ KT77s are said to be quite good for the money. I've had two amp builders tell me that they prefer the new GL KT77 over the uber expensive vintage GL KT77.

[Musica Amantem]

Originally Posted by Bombadil

I've spoken to multiple amp designers and tube dealers who are very high on some of the current production tubes. I've been told that this is sort of a second Golden Age of tubes. Gold Lion KT77s and KT88s, Tung-Sol KT120, EH 6CA7s (at a bargain price), the recently discontinued SED Winged C 6L6GC, some of the PSVANE tubes, and more, have been positively compared to classic NOS tubes. Even some of the lower priced tubes, like Sovtek EL84s and Tung-Sol EL34B have fans. And the JJ KT77s are said to be quite good for the money. I've had two amp builders tell me that they prefer the new GL KT77 over the uber expensive vintage GL KT77.

I believe variables are so inter-dependent with each other there is no specific unique combination that could be generalized. System components, room conditions, specific tastes in music and sound preferences, all bear vote in the final count. It is an unavoidable trial-and-error process to gradually find the two or three best combinations for each system assuming main components are not changed in the process. Otherwise one would have to start over.

In my current setup, 6V6's are anemic and lifeless compared to 6L6 GC (Russian) and GL KT88's. Depending on the type of music, I would choose one over the other between those two. Same with the 56 vs 27 in my preamp and whether I use the preamp or do balanced with the ZBit straight into the amp. Of course, I have not tested a whole bunch of possibilities, but I'm happy.

[robert_kc]

Musica_Amantem expressed my sentiments before I could finish typing.

IME the Inspire single-ended-pentode amp can be finicky about speaker synergy. My short answer is that the best sound quality depends on your speakers, your room, the type of music that you listen to, and your preference regarding which inevitable colorations suit you.

I listen to classical music and opera. I employ my Oppo player’s built-in crossover for 2.1 in order to off-load bass from my Inspire “Fire Bottle” SE Stereo Tube Amplifier HO and Klipsch RF-7II speakers to a 15” powered sub. I’ve tried almost every possible output tube in my Inspire amp (which was originally equipped with GL KT88). With my RF-7II speakers, my favorite remains the 6L6GC variants. Thus far the best combination for me is GT6L6 GE (performance rating 5), 5AR4, and Amperex (Holland) 6DJ8 – which sounds fabulous. With that said, I’ve been able to achieve good sound quality with almost every output tube I’ve tried - KT150, KT88 (which tend to sound bright with my Klipsch), EL34, KT66, 7581A, various new and vintage 6L6GC, and 7408 (6V6 variant that I received today) - when paired with the right input tube and rectifier, and when paired with a particular type of music (e.g., chamber music vs. large scale orchestra).

IMO, other important factors include pairing with the best bourbon or rye … phase of the moon … etc …

[Bombadil]

Has anyone tried a lower rated rectifier? Like substituting a 5V4GA for a 5U4G? Dennis told me via email that one can do this. Or even go all the way down to a 5Y3GT, which he also said was okay. I've got a handful of the 5V4GAs. They can't handle as much voltage or current, but the voltage drop is just 25. The 5Y3GT is really low with a big voltage drop - not sure there would be much reason to try it. Except that I've got some very pretty vintage ones just laying in my tube box.

[BearCityUSA]

Originally Posted by Bombadil

Has anyone tried a lower rated rectifier? Like substituting a 5V4GA for a 5U4G? Dennis told me via email that one can do this. Or even go all the way down to a 5Y3GT, which he also said was okay. I've got a handful of the 5V4GAs. They can't handle as much voltage or current, but the voltage drop is just 25. The 5Y3GT is really low with a big voltage drop - not sure there would be much reason to try it. Except that I've got some very pretty vintage ones just laying in my tube box.

Definitely try them. I have not found a better pairing with 6v6gts than a 6106 bendix red bank (5y3). Forget the numbers and roll. You may be surprised.

[nhparrot]

Originally Posted by Bombadil

Has anyone tried a lower rated rectifier? Like substituting a 5V4GA for a 5U4G? Dennis told me via email that one can do this. Or even go all the way down to a 5Y3GT, which he also said was okay. I've got a handful of the 5V4GAs. They can't handle as much voltage or current, but the voltage drop is just 25. The 5Y3GT is really low with a big voltage drop - not sure there would be much reason to try it. Except that I've got some very pretty vintage ones just laying in my tube box.

I have used 5AR4/GZ34, 5U4GB, 5Y3GT, 274B, 5R4GYA, 5Z4GY/CV1863 and 5U4G rectifiers in various configurations with 6V6, 6V6GT, KT77, KT88 and 6L6 in my amp.

[Bombadil]

Originally Posted by nhparrot

I have used 5AR4/GZ34, 5U4GB, 5Y3GT, 274B, 5R4GYA, 5Z4GY/CV1863 and 5U4G rectifiers in various configurations with 6V6, 6V6GT, KT77, KT88 and 6L6 in my amp.

Any favorite combinations? Or any that you felt didn't work out so well?

[nhparrot]

Originally Posted by Bombadil

Any favorite combinations? Or any that you felt didn't work out so well?

I overall prefer 6V6GT output tubes.

Overall top combos for me to date are:

Pope 6V6GT, RCA 5U4G, Raytheon VT231
Visseaux 6V6GT, Zalytron (Holland) 5Y3GT, Zalytron 6SL7
Bendix 5992, RCA 5U4G, Raytheon VT231
Genelex KT77, RCA 5U4G, Tung-Sol 6SU7GTY
Tung-Sol 6L6G or SED Winged "C" 6L6GC, Sophia 274B, Sylvania 6SN7

both the KT77 and KT88 output tubes are interesting when driven hard with a 5AR4/GZ34 rectifier

In my system the Sophia 274B has a mid bass hump and is not a good match with many output tube/driver combos that I have tried

[FloridaBoy]

Originally Posted by Bombadil

Any favorite combinations? Or any that you felt didn't work out so well?

The best thing to do is experiment with the tubes you have. There are just too many variables between systems to recommend specific combinations. Me? I like the 6V6/6L6 family of tubes in my rig. If you want to use ST 6L6G or 6V6G's use a 5Y3 rectifier. You can get Zenith ST 6V6G's for little money. They are rebadged RCA or Sylvanias.

The new production power tubes, IMHO, are excellent. My favorite power tube is the Shuguang Treasure KT66z. The GL KT66 and KT77 are also very good. The general consensus on the GL's is that they outperform the original old production. YMMV.

[Bombadil]

On my Inspire EL84, it is my perception that when using a 5V4GA the sound is a bit edgier. As in a bit too edgy. Smoother with the stock 274B or a vintage 5U4G.