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Atma-Sphere MA-1 Burn-In Process

Posted by ACHiPo (A) on September 28, 2021 at 17:51:49

I did a search and was a bit surprised I didn't find anything on amp burn-in on the forum, so I apologize if I'm duplicating a thread. Just thought I'd share my experience though the burn-in process.

I received my brand-spankin' new MA1s Saturday afternoon (woohoo!). I loaded up the tubes and plugged in the amps to cook about 16 hours overnight in standby. Ralph suggested 24 - 72 hours in stand by, so I cut it short, but I was impatient and the tubes looked good and stable.

Early Sunday morning I installed the amps in my system. No drama. Good. The music came softly to life (wife was still sleeping) and sounded, well, ok. (More about that in a bit) After 30-60 min I muted the preamp and flipped the middle meter switches into the "down" position (1 watt full scale) to adjust the DC offset. The meters on both amps jumped up to about half scale. I twisted the pot to minimize the needle's reading. If I went too far the needle started to climb back up, so I left the pot where the needle was at its lowest point.

I took the pre off mute and the music (and meters) sprung to life. I flipped the middle switch into the up position so as not to peg it when I applied more than a watt of power.

The sound...well, it didn't sound bad, but it didn't sound like my beloved M60s either. The increased dynamics were immediately apparent. Everything sounded much louder. There was also an edge. The music sounded like music--certainly no nasty distortion or coloration--but nothing like the effortless midrange I'd come to expect with the M60s.

A day later they sound ok, but are still missing the special sound (air, spaciousness, depth and width) I was getting from the M60s. The dynamics and power are definitely there--almost too much so as I do most of my listening while working at the computer and it's hard to find just the right low volume with the extra gain stage of the MA1. Not sure if the lack of air and emotion is the burn in, tubes, or amp/speaker combo.

Two days in and things are starting to sound more familiar and musical. There is more air, more spaciousness. Instruments are sounding more natural.

Ralph tells me it takes a couple hundred hours for the amps to hit their stride. I believe it. I'll update this as the sound evolves. Of course once it stabilizes I'll be itching to install NOS 6SN7s instead of the Chinese driver tubes.

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