Hi LS,

I'm happy my experience w/ the power tubes triggered the idea for you to put the el34's in in the IV.  I can see why the thought didn't occur to you for so long.  Most everything written here about the Mark IV is with the 66's in place.

I wouldn't be surprised to see someday you writing about putting the 66's back in though.  I actually have them back in my III.  And soon, I'll probably rotate the 77's in for awhile.  It seems they all have their strengths and I think I'll be enjoying revisiting them all from time to time. 77's for the awesome bass,  34's for the mid's and the 66's for the detail and other well documented strengths.  The first time I listened to a piano's decay via the 66's was certainly a jaw dropping moment.   Some day I may spring for those Psvane el34's you mentioned in the other thread. Lotta money, but if they are that much better than my tung-sols, it'll be worth it.

Lon, you are absolutely correct about us all having valid but different opinions on what tube set work best based on our differing gear,environments etc.  No doubt about it.

The reality check that keeps me from going overboard with all this nirvana searching is the reactions I see from my wife or friends when I put on a cool "stereo" kind of song like Fleetwood Mac's Rhiannon.  The talking seems to stop and they just sit in amazement at the sound.  Doesn't seem to matter which tube combinations I'm running either.    Makes me realize it's all good and there is no right or wrong, and also, for me, no set in stone tube combination.

What tube set I run is now just going to be a mood thing.

Greg

(btw, I know for most folks that read this, what I say is no revelation.  It's just some rambling of a first year tube nube figuring some things out for the first time.  It's been a really great year.)  

What KT66's do you use?

will, at some point you wanted me to let you know any impressions I had if I put the Tung-Sol KT66 back in the Mk III (main system) in place of the Genelax Gold Lion KT66.

Well, I did that yesterday for about four hours of listening. And I must say. . . I put the Genelax Gold Lions back in and signed a sigh of satisfaction and relief.

The Tung-Sol are very good, but there's a bit of upper midrange energy to them in comparison that can be excellent on some material, but that overall my system doesn't need. The Gold Lions are just richer and more stately in sound, an overall nature that I prefer readily. I could live with either but the Gold Lions are more to my taste.

I'm thinking of perhaps trying out the TAD one of these days but. . . not soon. As I'm not really using my second system at home much (man, I spent so much on it and it languishes unused!) I swapped the JJ 6CA7s that I was using in the Mk II at my Dad's place into the Mk III in the second system and put the Tung-Sol KT66 into the Mk II at Dad's. Nice! Still dialing that in a bit but the KT66 in the Mk II is a good upgrade, fuller, richer sound in his room (which is the best naturally equipted listening room I've ever lived in). They're staying there. . . Gold Lions would probably be better but not making that expenditure til I need to replace the present tubes.

Note: all tubes in this post are from cryoset.com -- I'll get tubes from there whenever I can.

I've got about 900 hours on my stock tubes by now. I've been itching to try something new.

Steve doesn't seem to condone the use of tubes more powerful than KT-77. But I'm curious what the ZMA would sound like with a bigger tube.

My fallback is to try out one of the KT66 you guys have mentioned. The TAD or Golden Lion specifically.

Yes the GL KT66 are bigger, more atmospheric, and less lean here, the GL drawing notably higher current. The Maxi Ip is 37 for them, and 25 for the Tungsols, both tests by cryoset. I got into a lot of trouble with Ron on this as one GL was defective and he was convinced it was the amp, not the tube, saying this high current tube needs very accurate biasing. I thought it was a funky filament. The MKIV being self biasing, I could not argue accept that I thought Steve knew what he was doing with his amps. When I gave up, packing then for return, he finally said he would send a single he had that actually had a little higher Ip. These tubes have been in hundreds of hours, no problems.

Just a heads up in case the current/biasing is somehow and issue with the ZMA. The factory ratings on these GL KT66 are Ip: 59 and Gm: 4900 if you want to check it out.