5751 tubes and Rogue Tempest?

Anyone used 5751 in place of the 12ax7 in a Rogue?
Yes I have.If you like your sound a little more laid back it is very nice.
I switch back and forth all the time.
Make sure you get good NOS 5751.
I initially swapped out the stock 12ax7 for a telefunken 12ax7 in my M-120 monos. Then went to the RCA command series 5751. The 5751 is a keeper.
12BZ7 is the ticket. Much better dynamic contrast and safe to substitute for the 12AX7 according to Rogue.
I think the 5751's sound much better and have a LOT more focus than the 12AX7's. The 12AX7's sound fuzzy in comparison. Have not tried a 12BZ7.
As I posted in more length in a similar thread, I preferred the RCA 5751 over the Telefunken 12AX7. The Telefunken was more dynamic, I guess, but 5751 seemed to give me a sweeter sounding system. But it wasn't so much the dynamics but rather the musicality and reduced noise that the 5751 gave. I describe it as like going from ultralinear to triode all over again. But whatever the actual proper way to describe it, I just preferred the 5751 and am happy with the dynamics of my system. And my system is plenty dynamic.


Rogue M-180 monoblocks with RCA 5751, RCA 12AU7, Gold Lion KT88

Rogue 99 Magnum preamp with RCA 5692

Kimber KS-3035 speaker cables; Kimber select interconnects throughout

Silverline Bolero speakers

The system sounds fine to me.

Caveat: the bottom line is that you need to try a couple of the tubes you are considering and see how they sound in your system. What worked for me may not work for you.
Reynolds853...How did the GL 88's improve your system over the stock tubes? Were your stock tubes EH KT-90's?

I actually never owned the stock tubes. I ordered the M-180's with the GL KT-88's - they were about a $300 upgrade from the stock EH KT-90's.

I would like to be able to give you a more insightful answer regarding the comparison of the two tubes, but I went with the 88's on instinct and haven't actually compared the 88's to the 90's. I asked the guys that own the local audio shop which they thought I should get and after talking about it they recommended the 88's. I don't recall the attributes they mentioned, but I have been very happy with the 88's. I do find that the combination of the 88's and the RCA small tubes I have make for a very musical system with a very low noise floor... I run the system in triode 99% of the time.

Sorry that I couldn't be of more help.
Thats ok I appreciate you letting me know. I talked to Mark and he suggested the KT-90's in place of the stock tubes so I ordered a quad. He matches and burns them in before shipping. My Tempest II came with 2 sets of quad EH KT-88's and I have no idea how many hours were on them or how matched they are. I have had problems with 2 tubes so I said screw it and ordered a new quad from Rogue.

You're welcome. When we talked with Rogue about tubing my M-180's we were told that one of the factors influencing Rogue's decision to go to KT-90's was that they were having quality issues with the stock EH KT-88's (no quality issues with the Gold Lion KT-88's however). Your comment about having trouble with two of your tubes may be an yet another example of the quality issues they were seeing.
That's what it sounds like. Mark didn't mention it but was quick to suggest replacing the KT-88's. I think I do remember Kevin Deal talking about the KT-88's on his website.

I talked with the guys at the shop yesterday regarding their opinion of the sound differences between the KT-88's and KT-90's (it also reminded me again why I went with the 88's). The comments they made were that the KT-88 is a little warmer, more delicate and three-dimensional than the KT-90. The KT-90 having more a little more slam and power.

I hope this helps answer your earlier question about the sound differences between the two tubes. As I mentioned, I didn't audition the EH KT-90 - I just went with the GL KT-88 right out of the gate and have been very happy.
Have the KT90s in my Cronus Magnum, and the GL KT88s in my Ayon Spirit 2 and agree about the sound as Reynolds853 described.

Use Tungsol 5751s in the Cronus, added some warmth