I've got two 75SE amps ... one powers the midranges only and another powers the ribbon tweeters only in my Selah line arrays.

Anyone have any experience (positive or negative) with "tube rolling" in these amps, or, have suggestions for where to inquire?

Thanks.

I've got two 75SE amps ... one powers the midranges only and another powers the ribbon tweeters only in my Selah line arrays.

Anyone have any experience (positive or negative) with "tube rolling" in these amps, or, have suggestions for where to inquire?

Thanks.


A lot of mystique and hype behind tube rolling. I have found in my experience that what I hear is often different but not necessarily better. What I have found is that merely rolling the 12AX7 gives the best overall best improvement as this tube is the first tube seen by the signal. I have tried many and the two best are NOS Telefunken Circa 1962 with ribbed rather than flat plate. Arguably the very best 12AX7 ever made is the NOS Telefunken with a diamond imprint along the bottom.....very difficult to find and if you are so lucky be preared to pay as much as $400-$500 /tube for a matched pair. Granted this tube can go easily 5000 hours or more but a steep price nonetheless. I paid $250/tube for a amatched pair for the one I just described. Another great 12AX7 is an NOS circa 1957 Mullard which is very subdued and great for mid range but I found just a little too laid back for me.
Not sure if your amp uses 12AX7 or 12AU7 or 12AT7 but you can buy ECC803 or ECC83 for instead of a 12AX7.
I would only buy from a reputeable dealer as there are many fake tubes on the market made in China that in some case are difficult if not impossible to tell from the original. Certainly you can find them on Audiogon or E-Bay but again I would be careful of fakes and you should always buy a matched pair. Below is a great summary from one of the local dealers I use regarding Telefunken

Telefunken produced some of the best tubes that have ever been made anywhere at anytime. They are remarkably devoid of any microphonic problems and tend to last a very long time. It is fairly rare to see a weak or bad Telefunken tube. The sound is characterized by many to be "mellow" or "dark" but really if you want to know how a tube sounds, you need to try it for yourself in your own equipment because it may sound totally different to your ears than someone else's. There are basically 2 different kinds of Telefunken 12AX7's. The "smooth" plate version has as large totally smooth plate surface. I believe that these are the earlier version. The later version has ribbed plates that look much like RCA plates. I really couldn't tell you the difference in the sound quality....like I said, buy one of each and try them both. There are allot of "fake" Telefunken tubes out there, you need to be careful. Any tube produced in the Telefunken factory should have a "diamond" molded into the glass in the base of the tube inside the circle of pins. If you don't see this diamond, then the tube wasn't produced by Telefunken. There are many Telefunken tubes out there that don't have the Telefunken name on them, but instead an OEM brand like Fisher, H.H. Scott,etc. These are true Telefunken tubes as they have the characteristic diamond in the base. This is true for other brand names of tubes like Amperex