Grateful Dead Music Forum

A place to talk about the music of the Grateful Dead 

 #134742  by Jon S.
 Sun Dec 08, 2013 8:36 am
Flipping a tube's like changing a light bulb so why not think?! :D
 #134743  by Smolder
 Sun Dec 08, 2013 9:41 am
Jon S. wrote:Flipping a tube's like changing a light bulb so why not think?! :D
lol... yah, with any other amp you're right, but my SMS is buried in the rack set up. A tab more of a hassle.
 #134744  by Jon S.
 Sun Dec 08, 2013 10:00 am
True. What I did was disconnect the power and output cords, remove the preamp, remove the top, swap the tube, then slide the unit back into the rack sans the top or screwing it back in, hook the cords back in, then plug it, just being careful when doing so as it's not screwed into the rack at the time. Was pretty easy even if not instantaneous.
 #134900  by cmc64
 Sat Dec 14, 2013 2:55 pm
SarnoMusicSolutions wrote:In mine... RCA 7025's.

I have two black short plate RCA 7025's that came with an Alembic F-2B that I have (it came from Leighsa Montrose, widow to Ronnie - she sold off some of his old gear and gave me a GREAT deal - very sweet lady - he was in the process of modifying it but did not finish it so it is not functional at the moment - when I have some spare cash I plan to Jerry-fy it and add a parallel effects loop for reverb) - anyway it came with a few tubes including the aforementioned but they look a bit rough and one of the other tubes it came with is shattered and as I have no tester I am a bit leery of placing them in my SMS. Anyway, I have a lovely G.E. 12AX7 I just placed in V1 and kept the stock tube in V2. About to give it a go!!

I also have four NOS Sylvania 12AX7's and I am going to give them a run after the G.E. test and hear what I come up with. I have a G.E. 12AZ7 in my H&K Bluesmaster and it sounds very decent so I am expecting good results. I fired up the SMS and then wrote this post so the tubes should be warmed to ready to sing. We shall see (hear).

If anyone out there has any experience with the Sylvania 12AX7's please let me know your thoughts on them. Also, as far as the "who knows what kind of shape they are in" tubes that came in a plastic bag with my F-2B is there any risk to my SMS if I try them out and they have issues? I certainly do not want to cause any damage!

Thanks for the tube rolling thread and any input!


 #134901  by cmc64
 Sat Dec 14, 2013 3:48 pm
Well, I can certainly say that the G.E. 12AX7 is an improvement. A bit more in the fine detail department, top end sparkle, tight, defined and controlled mids and bass. The middle pup is rich and full and there is nice twang from my bridge pickup that wasn't there before. Tunes like Cumberland Blues (for example) have definition and clarity without being overly bright or harsh. And my Mu-III, Tru-Tron 3X and Phase 100 are very happy effects. In the simplest terms, it is a step closer to that elusive tone we are all chasing. I wonder how the Sylvania's will sound? I want to give them a go but I am pretty happy at the moment!
 #137736  by wfrobinette
 Fri Mar 21, 2014 1:48 pm
I just scored a couple of Amperex Bugle Boy 7025's. To my ears the Amperex sound absolutely phenomenal in the SMS and much better than the RCA 12Xa7's long grey plates I had in there before. If you can find them at a good price it might be worth a try.
 #138090  by Bobbybriand
 Fri Apr 04, 2014 4:42 pm
SarnoMusicSolutions wrote:In mine... RCA 7025's.

Just in V1 right or both? I have a version of your smsjg model after you stopped using those JJ tubes and I had tried all sorts of NOS's for fun. RCA's are what u want foresure if your gonna take the Fender route especially 7025. I sold all mine off and even got more money than I paid for some. The tubes that came in my sms have black writing on them and are 12ax7wa's. You mention in the instruction paper about discontinuing the JJ's amen.
All my tubes that I acquired after I bought it had great results when tested (close to factory spec). Anyway those wa's that came from Mr.Sarno are the winners out of tonnes of combos Ive tried. I stayed away from GE. There was a very bad run of them late 60s n early 70s.
What was the original signal path tube wise for the twin ab763 circuit did it go 7025<12ax7 or 7025<2at7? Also did the post alembic preamp mod on the Fender plugged in thru vibrato jack sent the signal thru only 2 tubes before heading out the back to the MAC?
Who ever makes those 12ax7wa's boy are they clean. Maybe someone can elaborate. They came with the unit and won by far over all kinds of tube combos. I did run the RCA7025 that had the best scores on the tester and used one of the wa's in V2. I also never got my hands on a 5751. I heard those are the sweetest of the sweet. Very low gain factor and can be pushed hard without breakup but definitely have to follow it up with a 12ax7 in V2 due to its lower output freq.
Brad sry 3rd question are you still installing 12ax7wa's in your current production?