Is there a strategy in preamp tube placement?

@curiousjim - A buddy came over yesterday and we installed 4 of his olderTelefunken's in the phono stage in place of the Electro Harmonics. It was really really nice.

@lowrider57- I bought my Linlai's from Vivatubes, so I'm on the fence about buying a 2nd set from Grant Fidelity or finding a set of Ken Rad's

Presently, I have a set of Tung-sol's in the Gain position and the Linlai's in the Buffer spot. I still need to experiment a little more.

@decooney - The Full Music seems reasonably priced, might have to experiment.

I too have a Cary preamp that I bought earlier this year.  I got the SLP-05, and it has a pair of 6SN7 tubes for the balanced input buffer, and 2 pairs of 6SN7 for the left and right gain stage.  The stock EH tubes have good details in the treble and decent slam in the bass, but I found them to be a little too bright for my system.

So I bought 3 pairs of NOS RCA black plates to replace them all.  The RCA's are much warmer, less details but no harshness at all at the high end. The bass does get pretty low, but lack a little bit of slam.  Overall, I found them to be a little bit too dark.

So I changed the pair for the balanced buffer back to the stock EH tubes.  It sounded much better now with that setup (EH in the buffer, and RCA in the gain).  It restored some details on the high end, but without the brightness, and just a tad of improvement on the tightness of the bass.  So I kind of agree with @lewm that the tubes at the gain stage seem to have bigger impact on the SQ.

Anyway, I also recently bought some Ken Rad VT-231, based on all the praises I read here, and sure enough, they have very bad microphonic.   One minute into the first song I played with these KR, there was a sudden loud hum coming out of my speakers, and I ran to lower the volume down to zero, but the hum was still there.  I ended up having to power off the preamp to stop it.   I tried playing some songs again after a few minutes, and by chance I noticed a loud knocking sound coming out of the speaker when I just happened to tap the volume knob while trying to adjust the volume.  I then tried tapping the surface areas of my preamp, and every time it would be amplified and heard through my speakers.   I ended up returning them to the dealers and asked if he can find me some without the microphonic, but I haven't heard back.

Questions to you guys with the Ken Rad with microphonic.   How do you guys deal with this issue? or do you simply just live with it?   Thanks.

Hey @coachpoconnor, how are you liking the Linlai's?  I've been thinking about trying a pair also, but haven't pulled the trigger yet.   Also the Elite 6SN7 might be a little bit too tall for my setup, so I'm also considering the globe shaped ones available in Grand Fidelity, which are $400 a pair.   It's a lot of money to spend without hearing them first. Thanks.

re: " The Full Music seems reasonably priced, might have to experiment."

To @coachpoconnor, I went with them long before the Linlai came out, and was tired of chasing quality matched pairs and quads of vintage 6SN7s any more. A SET/Triode obsessed gear friend of mine turned me on to them a few years back. Its worth following the other 6SN7 thread on Agon for more info. I would not say they are better than Linlai, yet I do like the TJFM better in some ways then the psvane CV181-MKIIs, and vice versa in other ways. Different sounding tubes, comparing them to each other.

That’s where I started mixing them within the SLP-98 for an enhanced result. Like mixing in a little butter and lemon for a good pasta dish, hahaha. :)

If you have Linlai now, will be interested in your feedback if you mix them with psvane or TJFM later on. I started doing this to have at least 2-3 other type quad sets in reserve while I mainly keep my vintage stuff tucked away and rotate them in every once in a while. Honestly, no need for it after I got the TJFMs in rotation, and they fit and seat down very well in the 98. PM if interested, I get them from their largest distributor overseas, with fewer middle-men and handoffs in shipping, helps reduce shipping damage some, and this dist packs them well layered in cotton, good boxing. Cheap insurance actually.

They learned this years back after a series of tubes failing after poor packing/shipping. Mine have 2yrs run-in on them now. So far, like mixing psvane/tjfm. Having another quad of Linlai will be good. Thx

With KenRad, I've had problems with microphonics that were not totally curable, even in my Atma-sphere MP1 where the tubes are entirely enclosed in the chassis and my MP1 is 22 feet away from my speakers with a couch in between.  However, the problem was "tolerable".  Then I switched to RCA VT231 gray glass in the gain stage.  They're not quite as terrific as the KR but less microphonic, at least the pair I've got.  Much better in that regard. In my Atma amplifiers which sit next to the speakers, I use 12SN7s or 12SX7s (6SN7 with 12V filament); for some reason these are not microphonic at all.