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tube rolling first-timer

So I bought some NOS tubes to try in my preamp. It is my first piece of tubed equipment, and this is my first time switching out the tubes for something different. The pre is a Nagra PL-L. It comes with some Sovtek tubes. The tube complement is two 12AX7's and one 12AT7.

So, I've done a fair amount of reading about different tubes, and decided to start with some Telefunkens. I found a good deal on a matched pair of Telefunken smooth plate 12AX7's and a Telefunken 12AT7.

Here are my questions:

(1) when you are first learning about tube characteristics and your preferences in your system, is it best to stick with all one kind of tube and swap them all out, or should I first switch out the AX7's (leaving in the Sovtek AT7)... I'm just curious if people think there is a "right" way to go about it.

(2) Does one generally switch to all of the same brand tube, or do people tend to mix and match brands to their preference? Of course I recognize you need to use the same brand (and closely matched) tubes for the L/R channels, so I would stick with the same brand for the AX7's.

(3) Do folks have particular preferences or combinations of tubes that they have like for the Nagra PL-L and would recommend?

Thanks for your advice and recommendations.
dgaylin

Showing 7 responses by dgaylin

dgaylin OP
255 posts
 
Hey Rick, thanks very much. The PL-L only takes a single 12at7. Maybe that means it's not in the signal path and is just used for for volume attenuation? So I can switch all of the tubes to the Telefunkens (the two ax7s and the one at7) or I could try just switching the pair of ax7's first, and then try all three or try just the single at7 first....

any thoughts?

Thanks again,

--dan
dgaylin OP
255 posts
 
Thanks again Rick. Much appreciated.

--dan
dgaylin OP
255 posts
 
Thanks Jim. Very helpful. I am going to try some Mullards at some point. Just doing this gradually.
dgaylin OP
255 posts
 
Lenny -- that's a quite reasonable thought, and where I was initially. I guess from what I've seen the Sovtek tubes aren't that highly regarded, but also, to get new ones Nagra charges quite a bit (they specially select them) Then there's curiosity at play too. But I am half expecting to swap in new tubes and decide that things sounded better with the stock tubes.
dgaylin OP
255 posts
 
Yes certainly sseems I'm on the right track to experiment here and will do so with interest. Plenty of agreement on that score. Intersting, Jim that you prefer RCAs to Telefunken. I've got a lot of listening to do....
dgaylin OP
255 posts
 
Hi Samhar. I have settled on Mullards and RCAs as my favorites which I prefer over the stock tubes. I also have some Bugle Boys to try. The Telefunkens and Genelex were not my cup of tea.
dgaylin OP
255 posts
 
Interesting on the 7025's and thanks for the recommendations. I tried RCA 5751s and thought them not as good in my system as the RCA long black plate 12AX7s. The Mullards I tried were both short plate 12AX7s from the 60s (nice) but also the long plate O-getters from the late 50s (nicer).

Between the RCAs and the Mullards (12AX7s) the RCAs are a bit more balanced and dynamic, but the Mullards have a wonderful midrange that is really enticing. I am using the Mullard 12AX7s and RCA black plate 12AT7 -- seemed to be the best combo, although it started to get pretty subtle in trying the different combinations. The 12AT7 tube (single) does not seem to have as much affect on the sound, although I did not check this very scientifically.
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