Since it was mentioned about replacing the stock tubes, at least in the SV 236 MK I wanted to let anyone interested a possible option. I tried a number of combinations in mine, replacing the original Chinese military 12AX7B with some GE 5 star triple black plates ( 1950's ) in all three positions, then some 1980's RFTs I believe, finally one NEC up front in the driver slot and a pair of Raytheon black plates ( early '60's ). Found the bass a bit too heavy, not as open sounding as I wanted as well, but not bad.
The current set up is a Ten Kobe 12AX7 as a driver and a pair of mid '60's Tungsram ECC83 - this is the first combination that has allowed me not to touch the tone controls and actually use the by pass switch. Bass is tight and accurate, nice open mids and clear but not harsh highs, finally the amplifier is starting to really sing - if I ever put those original Chinese tubes back in it would be difficult to listen to.
The Ten Kobe is a great choice as a neutral tube that enhances the sound qualities of the ones for the left and right channel, finding that balance is the difficult part, and the Vincent needs something like the older Tungsrams, if you can find the silver colored ones from the 1950's even better, no latter than early '70's though, after that they are not nearly as musical.
I have been keeping an eye out for some early production Mazda and Valvo tube, 1950's, but prices are not cheap for a reason. I know many have their particular preferences, but a modern hybrid like the Vincent needs a dynamic,open and transparent sounding tune that has a well controlled bottom end. The choices are rather limited out there. Those early Tungsrams are highly coveted by those in the know for a reason. Most of the older ones are coming out of Bulgaria lately or ex Soviet counties.
If anyone with a stock Vincent SV 236 is thinking of changing tubes start with my suggestion - you will save yourself time, money and guess work.
