[medium jim]

I would also consider talking to Kevin Deal from Upscale Audio. They test all tubes extensively including for microphonics and grade them accordingly. I have had great experience with Upscale.

Kevin is a good guy, albeit a bit pricey on tubes, but who isn't anymore.  I was thinking about $25 to 35 a tube.  I have a collection that mostly came from vintage guitar amps and the like.   The 12AY7 was usually used as a Phase Inverter tube, but in the mid 1950's it was also used as the 1st and 2nd gain stages.  I also have a lot of NIB/NOS 6V6's, 5Y3's, that I hoarded for my Fender Tweed Deluxe and Black Face Deluxe Reverb amps.  Some are Jan/MIL spec...plenty of 12AX7's, again pulls that test like new, GE, Telefunken, Mullard, RCA, etc.   

I decided to let many of them go as I have more than I will ever need in my lifetime.   I will price them to sell and all will be tested on my EICO 667 for mutual conductance, leaks and shorts. 

Jim

[TJHUB]

I may have made a mistake or a genius decision.  I contacted several tube vendors today.  To be honest, none of them impressed me.  Brent Jessee, good tube vendor or not, is off my list.  It wasn't until I called Andy at Vintage Tube Services.  He was the ONLY tube vendor familiar with my preamp and it "special" needs.  It turns out the gain stage is hot, and therefore sensitive to what tubes are used.  He was also the only one to explain the MU-follower design my preamp employs.  So after a discussion with him, I was convinced I needed to follow his advise.  So I ordered (4) tubes from him.  It's a little more than double what I'm gettting refunded for the RCA clear top blunder, but it could be worth it in the long run.  I got quite an "education" today.  Andy is a little on the pompous side, but his knowledge allowed me to look past that.  I hope I made a good decision to buy from him.  So far Rogue Audio screwed me over (and I told them that...nicely), Brent Jessee failed me, and Freo-1 was an extremely great guy and sent me some tubes to try (which I'm back to using right now).   

For the record, buying tubes sucks!

[TJHUB]

I received my new tubes from Vintage Tube Services today.  I think Andy is a freakin' genius!  He sold me (4) 1950's TUNG-SOL 12AU7 tubes.  This little journey of mine had me telling my friends I was selling the Rogue preamp to never mess with tubes again.  And anyone that knows me knows I meant it.  I've been screwing around with this situation since early January.  I've spent a lot of weeks just pissed off about all of this.  I had a sound that I thought was damn near perfect last December.  I knew there would only be down hill from there, but it happened way too soon!  I can already say that I'm back to something that I can say seems damn near perfect again. 

I can't even describe all the great stuff I'm hearing.  All I can say is that everything just seems right.  The clarity, tone, detail, sound stage, imaging and separation, and level of realism is just fantastic.  Im not hear speakers again, I'm hearing music from a sound stage.  If these tubes settle in like all the other tubes I just spent 100's of hours breaking in, they will be everything Andy promised me. 

I really hope I can post this weekend that these tubes landed squarely where I hoped they would. 

[FullRangeMan]

In the 90s VTS advert in the late FI magazine they just bought about 10 miilions tubes from the USA army.
If I live in north america I also would buy tubes from Andy.

FWIW, preamps need hi quality tubes and it is a picky find some suited, these and others reason I dismiss preamps in favor of a power amp with a sensitive input stage with a volume control.
Happy listenings

[dB Cooper]

My system is already sounding nearly normal.  These tubes are changing fast. 

I wish I had a better idea of what I'd hear when the tubes were giving up before it actually happened.  I was blaming a recent change for the issue I was having, and no it may just turn out to be a horrible coincidence that my tubes started to fail at the same time. 

And the sound had degraded even more than I was realizing.  Of course this is obvious now...

What makes it hard is that the changes are gradual unless a tube flat-out fails.