Good eye. That PT does appear to be smaller than the one on my KT88 High Output amp.

Love the look of that WE6SN7 Plus.

Dennis' measurements on my Inspire PSE show that it has less output power with KT150s (21w) than with KT88s (23w).

Yeah. It can use all of those tubes but won't have any more power than the KT88.

Interesting. I have the KT88 firebotle and I really prefer the 6v6 types in my amp over the KT88. In fact I like most other tubes in it than the KT88. Good eye spotting the smaller PT. Wonder if it is voiced for those tubes running at lower power. Interesting idea.

Dennis says that he thinks that SEP for pentodes/beam power tetrodes really is the best configuration verses strapped SET. So far he is really liking the Nesstone 6550, which he calls "6F6s with some chutzpah". Apparently it is a re-issue of an older tube out of China, but I could be mistaken. Dennis says the Blue Racer is good for 2-7W, depending on what output tube is being used.

I believe the Nesstone 6550 is based on an old Shuguang design. Very inexpensive. Same for their EL34, which I believe was Shuguang's low-cost copy of a Mullard EL34.

Any CJ5 owners out there that have done some tube rolling? Curious about rectifier options. Sent message to Dennis but we all know how busy he is. CJ5 comes with a Sylvania 5Y3G rectifier. What others have you tried? Wondering if the Brimar 5Z4Y or Mullard 5Z4G would work. Also any other 6C5’s or 6J5’s you like. Currently using 1937 Raytheon 6J5’s with the stock RCA 6C5’s and Sylvania 5Y3G rectifier. Thanks!

I have a quad of the 6550's coming in to retube a pair of McIntosh MC-60's I've just finished restoring for a friend. I'll give them a go in one of my SE/Inspire type amps as well to see how they sound....

Nesstone has some of the least expensive tubes anywhere.

I see they are no longer offering their low-end EL34. Perhaps the Shuguang factory problems have impacted their supply. They were selling a quad of them for around $42. Now they have the EH EL34.

They are still selling their 6L6GC-NT for $11.59 each.

They source tubes from China, Russia, anywhere. A classic rebrander from the days of yore. But then again, so are Mesa, Groove Tubes, Ruby. It used to be that Ruby was very strict in their testing procedures and their EL34BSTR were very close to the original Mullard EL34 xf2. I don't know how true that is anymore.

The Shuguang EL34-B is also a close copy of the xf2. This may be what Nesstone was rebranding, or a version of it.

I get tempted to buy some of these but I have too many power tubes already and I really like my Gold Lion KT77 and vintage Sylvania 6CA7, so there is no reason to buy more.

Same for the Nesstone 6550. I have quads of the GL KT88 and the Tung-sol KT120 & KT150. How many of these do I need? But $95 for a quad of 6550 is certainly a great price.

And the last set of Groove Tube 6550s I picked up recently were strong as new testing GE 6550As....

Does that mean Dennis prefers straight SEP vs. triode strapped?


I don't know if they are re-issues, but I bought an identical-looking pair years ago and they were fine-sounding tubes. Nesstone does a good job with testing and matching.