Anyone compared BAT Rex vs. Atmasphere MP-1?

Rtml, thank you for the great description. I find myself leaning towards a more rich(not overly-ripe, though) and powerful sound. I had considered ARC, but since I will be buying used, I didn't want to deal with trying to decide between the Ref 2, 3, 4, or 5 to find where the "sweet spot" for price versus performance was.

Simontju, I will ask Victor. He is always great with technical advice - whether about his products or just engineering in general.

Hello Darkmoebius,

Just wanted to take the opportunity and give a plug for the BAT Rex. I don't think you'll find a preamp that dives deeper into the texture of sound as the BAT Rex. That's what I consider detail!

At the same time it does it with such a sense of authority and grace, never blinking an eye, a feeling of ease to the sound that invites one to listen in to the music. For me it is such a pleasure to own and I wish you luck finding a pre that you'll feel the same about.

best,
Tom

I would like to ask Raquel to elaborate on the Rex not being able to be on 24/7. The reason I ask is that I have mine on 24/7 (breaking in new speakers) and you have me worried. :-)

Madflloyd:

Some tubes in some tube power supplies can pass a relatively large amount of current and will wear out like output tubes in a power amp will wear out (certain tube preamps actually use output tubes in their power supplies - the ARC Reference 3 uses a 6550, and I believe the big multi-chassis Jadis used to use EL-34's). For example, when Stereophile reviewed the BAT Rex, they went through a couple of 5AR4's in the power supply over the course of several months of leaving the preamp on 24/7 (which they evidently did at BAT's suggestion). The review suggests that the BAT is fused to protect against tube blows in the power supply - you need to consult your owner's manual or ask BAT whether 24/7 operation poses a safety issue.

The other circumstance in which I would tend to think twice about 24/7 operation in a piece of equipment using small-signal tubes (i.e., tube preamps, tube DAC's, tube tuners) is if the tubes are run near their maximum voltage rating. Basically, such a tube will face the same wear issues that an output tube in a power amp will. It did not escape me that the Rex is said to run really hot, but this could be nothing more than the fact that it has a ton of tubes in it - I don't know how its various tubes are run relative to their maximum voltage ratings.

If, however, a tube preamp has solid-state rectification and does not feature a hot-rodded tube circuit (that would be the vast majority of them), I will run it 24/7 in order to maximize sound quality and tube life. As for why 24/7 operation would extend tube life, please see my comments about small-signal tubes and tube performance in the following thread:

http://forum.audiogon.com/cgi-bin/fr.pl?aamps&1281657617&&&/VAC-Signature-MK2a-w-phono-users

I hope this helps.

Raquel, just for clarification, the BAT should be left on standby when not in use? Just not 'on' 100% of the time. One could turn it off if going away for some time.

I thought the initial surge of current into a cold tube was the detrimental factor.

I also hear no sonic difference within 5 minutes of coming from totally off, vs. 5 minues of coming out of standby.

I'm not sure why Stereophile had problems with the 5AR4s. These Sovtek tubes cost $20 each, so it is not a big deal. Nonetheless, something must have been not quite right, and I agree to burn-in the unit for a few hundred hours for a review. Also, it is practically unheard of for a NOS GZ34 to die. Some of these have been in operation for a few decades.