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Biamping Maggie 20.1s: Amps and Xover Frequencies

I am trying to optimize the sound from a pair of 20.1’s – currently driven by a pair of VTL 450 signature monoblocks (450 watts into 4 ohms). You’d figure that is plenty for the Maggies, but I am not totally wowed in the dynamics and openness category. I’ve heard that biamping makes them more dynamic and open, and want to try that route. To that effect, I’ve just ordered a Marchand XM-44 active Xover with 0.5 db attenuators, and am currently selecting modules. I’m also selecting an amplifier to drive the low frequency drivers. I don’t want to invest a ton in trying out this approach, but I want to make sure I am getting a sense of what it can do. So – my questions relate to amplifier selection for the bottom end and Xover frequencies.

For amplifiers, my price range is $2k-$4k, but I’d really like to stay near the $2k level for now and maybe upgrade later if warranted. Here is my current working list of amplifiers in approximate order of ascending price:

Bryston 4BSST
Bryston 7BSST
Innersound (not sure which model to consider)
H2O 250 Monoblocks
Parasound JC-1
McCormack DNA-500
Pass labs x350
Edge NL10
Pass Labs x600

I think I’d like to go with the Bryston 4BSST to start, but would like comments and other suggestions. The VTL’s would power the mids and highs. A digital amp would be great for power consumption considerations, and I know they do well on the bass (I’ve owned PS Audio), but still find myself hesitating a bit. More comments?

As for Xover frequencies, my review online indicates the following:

Stock high-pass (HP) is 6dB (first order) with a -3dB point at 230Hz
Stock low-pass (LP) is 18dB (third order) with a -3dB point of 116Hz

Recommendations include:

Increase LP to 140Hz (same 18dB slope)
Increase HP to 250Hz (same 6dB slope)

The second recommendation also included moving the LP to 110Hz instead of 116Hz, but I can’t imagine that 6Hz is audible in this case.

The Marchand Xover modules aren’t too pricey, so I intend to get the stock settings (230/6 and 116/18) along with a 140/18 and maybe a 250/6. Are there any other combinations out there worthy of trying? If I took a shotgun approach, should I stick with the specified slopes of the HP and LP units and just try different Xover frequencies? How much of a change is significant for both the LP and the HP (e.g. 10%).

Thanks Very Much, Peter S.
peter_s

Showing 1 response by loontoon

loontoon
301 posts
 
I can't emphasise enough the that amps on bass make a huge difference in sound, they control the pace. I learned this long ago when I subbed in a B&K amp for a Muse 160II during an all night session with an old freind. He's a music buff but no audiophool.

When the B&K went in I heard it right off but said nothing, it took him maybe a minute to ask me what just happened to the music.

When I moved up from the Muse to a Threshold there was again an increase in bass quality and speed but nothing like from the B&K to the Muse.

BTW this is all on Maggies.

As for X/O slopes, get a RANE 22, it's adjustable, not the cleanest audiophoolish device out there, but they can be had on the open market for about 1-200. Use it to find the settings you seek then swap for the Marchand unit, then------ sorry but find a used Bryston 10B. Yeah you'll hear it, the problem with maggies, is you hear freakin everything. I wouldn't rush to find a Bryston but keep you eye out for one a good price.

I'm not as keep on the Bryston amps as I am the 10B X/O.

das loon
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