Anyone compared BAT Rex vs. Atmasphere MP-1?

The preamp is designed for 24/7 operation. IMO you get better bang for the buck when the preamp is operated when you are playing music, rather than using up the tubes while you are at work or asleep in bed.

It warms up quickly, much faster than in years past, due to better regulation and better coupling caps. Two hours is more than enough for the preamp to settle out so 24/7 operation really doens't win you anything with it like it did 10-15 years ago.

The power supplies (8 of them) are all tightly regulated so the use of SS or tube rectification isn't relevent; the rectification is all handled by HEXFREDs. The highest voltage drop on any tube in the unit is about 150 Volts, the B+ and B- are both regulated at +/- 250V.

The 6SN7s in the unit tend to last about 10,000 to 30,000 hours (GT, GTA or GTB, although seriously we don't know how long the 6SN7s last; some seem to last literally for years). The 12AT7s (used only in the phono) tend not to last as long. IF you run the preamp 24/7 we used to recommend replacement of the 12AT7s every 4-5 months; in the Mk 3.1 (the latest version IOW) they seem to last considerably longer but the preamp is so recent (came out a year ago) that we don't have good numbers on that.

Mr. Karsten: Many thanks for your responses. The 6SN7 Sylvania chrome tops in my VAC Renaissance amp, used as driver and splitters, are beginning their eleventh year of use (in on/off service), and for all I know, they may have previously seen service in somebody's T.V. :)

Just a couple of quick notes here, don't mean to overburden the forum.

One - regarding the extended tube life with 24/7 operation... while a common opinion, it is most definitely not universally agreed upon or shared. One could construct many different cases, but in my opinion, in ***general*** in normal home environment turning the equipment ON and OFF will produce longer tube life.

Furthermore, continuous operation will, without any doubts, shorten the life of most electronic components. Whether this is justifiable by potentially shorter readiness times - is up to the individual user to decide.

Regarding the 5AR4 tubes - their quality level is generally quite high, but we certainly went through a less than spectacular batch. As the manufacturer, we do our best trying to shield the customer from such problems, but that is not always possible in timely fashion. For instance, we stopped using the Sovtek 6V6 tubes entirely, at one point. But some problems only manifest themselves weeks or months down the road.

All tubes in BAT equipment operate with very significant deratings. The output 6C33 tubes operate the hardest, at about 60% of maximum stress, other tubes are typically used at far less than 50%.

Victor Khomenko
BAT

Raquel, yes, those old 'chrome dome' tubes are pretty impressive- I've seen them as original parts in equipment that is over 50 years old, still testing as strong as new tubes. We have seen them go over 50,000 hours in our stuff and I would not be surprised to find out that some of them could do over 100,000 hours in the right circuit. They sound nice too :)

Mr. Khomenko:

Thanks for the input on the issue of tube life and 24/7 operation. My experience is that, while most people are aware of a debate regarding 24/7 operation and solid-state gear, few people who own or sell tube gear are aware that some manufacturers advocate 24/7 operation of equipment using small-signal tubes in order to extend tube life (my posts on this issue tend to create surprise).

Assuming the conditions necessary for 24/7 use are present that I describe in the links referenced in my posts, the only thing I worry about operating 24/7 with either solid-state equipment or small-signal tube gear (aside from not being home to disconnect equipment when an electrical storm passes through) is what it's doing to the caps, which tend to be rated for only a few thousand hours, but caps will often far outlast their ratings and are relatively cheap and easy to replace, while thermal cycle damage to transistors from on/off operation, particularly where the transistors have gone out of production and the amp thereby becomes worthless, or thermal-cycle damage to irreplaceable, cherished NOS small-signal tubes, is not cheap. If I owned BAT gear (and I may one day, as my system is fully differential balanced from turntable to amps - that's why this thread, about BAT and Atma-Sphere gear, caught my eye), I would follow your instructions and turn my equipment on and off. With all due respect, however, your advice does run contrary to the evidence I have described in my posts referenced above and in numerous other posts I have made over the years here.