I’m pretty sure I know what I want to hear………………, and by extension I think other people would groove on what “I” hear. We don’t want that to be messed up with a “different” sonic profile, do we? Nope.

Yeah, “different”, when applied to a device with only three tubes in the signal path could be catastrophic…., so the 14F7 signal tube was chosen. It was chosen because I’d bet you dollars to doughnuts that every 14F7 (REGARDLESS of what box it came in or what is silk-screened on it) was made by Sylvania on the same production line building the Sylvania JAN-CHS-6SL7 and it’s 12.6v filament sister the JAN-CHS-12SL7. The 14F7 uses the Sylvania developed, Loctal socket as compared to the standard “Octal” 8-pin socket used by both the 6SL7 and 12SL7. Many companies made the 6SL7 and 12SL7….., not so with the 14F7, you’re pretty much guaranteed a Sylvania tube. The Uber 7 is being “voiced” using the Sylvania…….., so different would be unacceptable…. :)………., besides, have you priced out a trio of matched Army/Navy 6SL7’s these days? I have on-hand a CASE of N.O.S. 14F7’s and the five phono stages will ship with a set of these tubes…. possibly even a complete back-up set as well… why not spread the love? :)

The reality is that by removing as many of the variables as possible, I’ll be able to deliver the consistency required of an amplifier designed to amplify a signal a thousand times smaller than the average CD player puts out.

It’s important to note that I’m deviating from the original tube type used in the original Marantz 7 circuit. I believe the only reason Saul used the smaller form-factor noval socket 9-pin tubes was……. real estate. Yep, after all, six of these things had to fit into that chassis, AND, space was so tight, they even had to poke out the back of the unit for them to fit.

Not only smaller, these 12AX7’s were also cheaper………as I’m certain the accountants were also involved in the decision making process. These things never change.

The larger 14F7 is truly a beautiful sounding tube, IMHO it has more “air” and certainly more….. “body” than any of the 12 _ _ 7 tubes can muster and will help get us a little bit closer to that “magic” formula. I think Saul would nod his head in approval of the choice.

Speaking of choices……….the next installment will cover the other device choices, ie., resistors, capacitors, etc., So stay tuned and buy more vinyl. Cheers! Matt.

Uber 7 Phono Amplifier - Design Choices... the vacuum tubes.