Bottlehead SEX amp and Tung Sol 6SN7GTB Experiment – First 2 Days
Stumbled onto a Bottlehead thread that revealed the possibility of running 6SN7’s in the S.E.X. amp. Fun.
Of course, the circuit is not designed for these tubes, and though they are within spec, there’s little documented feedback available. The assumption is that the 6SN7’s will have a shortened lifespan. Some users posted that they enjoyed these tubes in the amp, but there isn’t much to go on. I just want to know how it sounds in my system. In the end, perspective is crucial and I know that, at least, will be provided.
I think it will be an interesting experiment – especially for an inexperienced Bottlehead. Let’s plan to let them burn in for 100 hours before making final decisions on sound quality.
1:00pm installed the new production Tung Sol 6SN7GTB
The hum I recently battled with some minor modification (with direction from the BH forums) is back….no wait, one of these tubes is simply noisier than the other. Swapped the tubes and the humbuzz moved along with the offender. Oh well, not a showstopper. It’s only audible on my Nighthawks, though it is significantly louder with the TS.
First thought: the mids and highs have more clarity. Not sure if this is extension and possibly a more mid-forward presentation – if so it’s subtle. But nice! – I like that, as voices have more presence. Maybe it’s just that my RCA 6DN7s are old. More touch and dimension at first blush. Acoustic instruments and voices are airier, yet have the presence I was missing. Bass is definitely more rolled off vs the RCA.
About 24 hours play time.
There’s greater extension in the high frequencies, and more dynamics with the Tung Sol. More sparkle. Bass performance lacks extension and weight.
The darker character and audibly lower gain of the NOS RCAs could just be old vs new production. Would be nice to have new production 6DN7s for comparison.
And, several days later we’re back to the stock 6DN7s. The 6SN7 were lean, with a subtle lift in the upper mids and high freqs and a substantial rolloff of lower frequencies. Interesting test that gave me perspective on the amp. It sounds so good with the stock 6DN7.