The myth of the powered woofer

[David Matz]

I have been auditioning a variety of amps recently. One of the things people assume about the new generation of Logans is that because they have a powered woofer, they can use a low powered amp to drive them. Furthermore, since the woofer is powered, one may assume that the bass of the amp should not be much of a factor.

However, in my experience I have found that the bass does vary greatly from amp to amp. Bryston, Sanders, and CJ 350 among others all have extremely powerful bass slam. Most other amps do not, which to me, takes away much realism from the music.

Can someone explain this?

Has anyone tried bi-amping the new generation Logans?

 

[Rich]

I always thought that the amp wouldn't matter that much for bass quality on the newer Logans because of the internal amp. I was much surprised, then, when I auditioned a Sunfire amp and an Anthem amp on a pair of Vantages. The Sunfire produced deep, tight, powerful, accurate bass; the Anthem exhibited loose, wooly, flabby bass. Everything else remained constant -- only the amps were changed. The difference was night and day and certainly made a believer out of me that the amp does matter.

Later, I asked one of the engineers at Martin Logan to explain this experience, and he said that the internal amp can only amplify the quality of the signal that it is given. In other words, garbage in - garbage out. So I don't think it is so much the power of the amp that matters, but the quality of the amp. It just so happens that a lot of quality amps also tend to produce a lot of power.

I have found that my Sanders monoblocs, my Sunfire 5400, and my Pass Labs X-350.5 all produce wonderful bass with my Summits. My CJ Premier 140 tube amp, while still decent, is not near as good for bass on my Summits as these other amps.