NOS Tubes for Rogue Tempest II

It's hard to pinpoint differences in 5751 vs. 12AX7 for me, since individual tubes in each genre sound different (like the Mullards/TFs). But I think the 5751s image a bit better for me. Like, center images like vocals are more, well, centered, and there seems to be a bit more width. Not drastic differences though.

One thing I can say though, is I tried some variations with new production tubes (JJ Ecc82 gold pin, bare bones TungSol 12AX7) and that was largely disappointing. I wanted to like something new just for $ reasons, but no dice. The Mullards with the JJs turned out "OK" - not great, not terrible - but after a while listening got boring, so I moved on...

My power tubes are stock - EH KT90s. I've never tried changing them (and there don't seem to be many kinds of KT90s out there, and I need 8 of them so that can get pricey!).

Yes I agree the power tubes can get pricy. I'll get there sooner or later and thank goodness I only use 4. It does seem from what I am reading that the 5751's are working better in most systems. I will try some those RCA cleartops before long.

I have a Rogue 99Magnum preamp and M180 monoblocks. Here's briefly my experience, and if someone wants me to expound further, please let me know.

Preamp: Looking at the front of the preamp, the two sockets on the right are the amplification pair, the two on the left are the driver pair. It is most critical to put the quietest tubes in the amplification side.

Preamp: NOS RCA 5692 in amplification sockets, Sylvania 6SN7-GTA in driver sockets. Too much sibilance for me. Moved Sylvanias to amplification sockets, 5692's to driver. Way, way, way too much sibilance for me. Sold Sylvanias to another guy in the shop who has a darker sounding system and he loves them. I went with all RCA 5692s in preamp and am very happy.

M180 monoblocks: Got the amps with Gold Lion KT-88s. Replaced the 12AU7s with RCAs. Put a Telefunken 12AX7 in and wanted to love them - they are rare and last forever! - but the RCA 5751s just sounded more pleasing to me. In terms of quietness, it was like going from ultralinear to triode all over again.

Someday I may try some Mullards in the 12AU7 position.

And please take this in the context of my system: Kimber Select interconnects, Kimber KS3035 speaker cables, Silverline SR17.5 speakers with Mundorf S/G/O capacitors (soon to be replaced with Duelund VSF caps).

Samzx12:

I went back and reread your post. And before I add more to this thread, I just want to say that I agree with our Red Wings fan from Detroit: the choice of tubes is very personal.

I was going to follow-up my first post with another saying that I should have asked you what you were trying to achieve, but you did say that, "I want a little more transparency or pop yet retaining overall smoothness and good bass."

I would have said that if you were trying to brighten up a dark sounding system, or add more “air” and “sparkle”, go with the Sylvanias in the 6SN7 position. If you were not trying to enhance that effect in your system, try the RCAs - they offer a good balance of smoothness and bass, and you don’t have to spend the $$$ on the 5692’s to get those qualities. But either way, make sure you get a 6SN7 with low microphonics.

For the 12AX7, the Telefunkens are more dynamic than the 5751s, but I went with the 5751 because I liked their musicality - and they lowered the noise floor on my system even further. But your use of the word “pop” would tend to make me think Telefunken… but my experience is probably more limited than the others contributing to this thread and I would not discount differing opinions. But in my system, no matter how much I really wanted to like the Telefunkens, I kept coming back to the 5751 and relaxing and listening to music with a smile on my face.

But my system was already very transparent and detailed, so that's why I have been moving away from tubes that are usually described as bringing out "air" and "sparkle"... my system doesn't need help in that regard. So for me, the RCAs have been a really nice balance. And like I said in my first post, the Sylvanias in my system were unacceptable, but for another guy that comes into our local shop and whose system had a darker sound, the Sylvanias worked out really well.

I agree totally about the 5751's. They made quite a difference over the stock 12AX7's. More clarity and focus. I do have some RCA clear tops that I will put in sometime soon for comparison. As far as the 6SN7's I bought the NOS Sylvania GTB tall bottle and things improved more in fact much more. I also ordered from Andy at Vintage Tubes some NOS Sylvania GTA chrome tops so can't wait to get those. These particular tubes are suppossed to be very close to the Bad Boy and 6SN7W's from what I was told.