12ax7 vs 5751

a quickie update, i contacted the shop in hong kong about my kt88-z`s. they should be here next tuesday. customs have my tubes and have just released them. they had them ages too grrrr! no sign of my ge 5751`s though but to be fair it states in their advert it`ll take 20 to 25 days so hopefully they`ll be here next week too

I have not read every post in this thread, so I will apologize ahead of time if I am repeating any previous comments.

I have Rogue M180 monoblocks that for a year or so I used with Silverline SR17.5 bookshelf speakers. I used the 5751 with them and it was great. I eventually acquired some Silverline Bolero floorstanding speakers and the 5751 didn't work well with them at all. The sound was just, well, blah. I replaced the 5751 with a Telefunken rib plate 12AX7 and the system was dramatically improved. With that substitution the tube compliment in my amps was Telefunken rib plate in the 12AX7 signal tube position, RCA 12AU7 tubes in the driver position. I have since replaced the RCAs with Telefunken rib plate 12AU7s.

I also have a pair of Telefunken smooth plate 12AX7s. I put them in the signal tube position and both me and a buddy noticed that the leading and trailing edges of transients were slightly smeared compared to the rib plate. I prefer Telefunken to all other tubes I have auditioned and/or used in my system (the others being RCA, Tung Sol, Amperex). But to me the smooth plate Telefunken is slightly warmer than the rib plate. Both are very, very clear, but I preferred the dynamics and crispness of the rib plate, and once they break in, mine were NOS, they are actually quite sweet. Smooth, clear, dynamic, fast.

Also, in my headphone amp I have a smooth plate 12AX7 and smooth plate EL84s, but I plan to replace the 12AX7 with a rib plate - it's on order and should be here soon. We'll see how that goes, in that application the smooth plate may be the ticket!

Anyway, back to the original question, I think the 5751 is a great tube, but I've been very happy since moving on to the Telefunkens.

Reynolds
When you say "the leading and trailing edges of transients were slightly smeared"...
Does that mean the high frequency is smoothed out? Sorry if the ? seems silly but I have Focals and they seem to be a bit on the bright side, just wondering if tube change has the potential to balance that out a bit. Of course much of the sound depends on the recording.

i did some rolling to and forth between the ei elites and the telefunkens today. there really isn`t much if anything between them. the telefunkens definately have a wider soundstage. the sound seems to go beyond the speakers which i really like but in pretty much all other area`s i couldn`t really tell the difference. the ei elites, one side is slightly microphonic but again it doesn`t really effect the sound performance at all.

i have my pioneer bluray player plumbed into the amplifier and watched shrek earlier. the sound was really good. music scores in the film sound excellent and voices throughout the film sound very natural. of course there`s no explosions or the like in this film so i can`t comment on stuff like that plus i have to think of the neighbours! music on this film certainly has some punch though!

by the way i`m from the uk and had our first snow fall today! i`m praying it stays for at least some of the week so i don`t have to go to work lol more listening time for me hopefully!

describe microphonic