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Xover on MJA Pro 50 sub

Discussion in 'Subwoofers' started by michaelab, Jun 1, 2003.

  1. michaelab

    michaelab
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    Right, my budget AV Receiver (Marantz SR4200) has a fixed xover for bass management set at 100Hz. That means, in theory, if you set your speakers to "small" and sub to "on" your speakers won't get given anything below 100Hz and instead that will all get routed to the sub.

    Now, the MJA Pro50 only has a single xover knob which applies to both hi-level and lo-level inputs (unlike, say, the REL Quake, which also only has a single xover setting but you can configure it so that it only applies to the hi-level input and not the lo-level).

    So, I had a problem because for music I have the xover at its lowest setting (40Hz) which I found to be best. I have the hi-level input connected to the speaker terminals of my stereo amp along with my speakers. For music that's perfect. No worries.

    However, it meant that I had to compromise for AV and tell my Marantz that I didn't have a sub and set my front speakers to "large". That way the LFE (.1) channel would get sent to the fronts along with all bass content from the other speakers and then the sub would handle anything below 40Hz, and the speakers would just have to struggle with the LFE sounds they would also get sent. It means not having a proper LFE (.1) channel and missing out on proper bass management. Now, I was just about ready to remove the low level connection from sub to AV amp (because it's not needed in the above scenario) when I thought I'd try setting my front speakers to "small" (the rest are already all set to small) and set sub to "on".

    Whoa! What a revelation! :eek: I hooked up my laptop and some test tone generating software to the Marantz and ran through the frequencies from 20 to 200 just to see if I was missing anything. In theory, I wouldn't get anything between 40Hz and 100Hz because the Marantz would send anything below 100Hz to the sub (and not the speakers) and the sub would only cut in at 40Hz. What I in fact got was a pretty smooth (just judging by ear, I couldn't be bothered to get out all the measuring gear) response all the way from 20 to 200. There was an ever so slight drop off at around 90Hz but it really was minor. I then tried a few DVDs with 'appropriate' :D scenes eg: Neo and Trinity destroy the lobby in "The Matrix", the massive gun battle in "Heat" etc. The difference was night and day. I suddenly had all that weight to my movies again (and now of course, because of individual gain for hi and lo inputs I can adjust the bass response for movies and music independently :cool: ).

    Watching TV was also soooo much better. It had all sounded rather thin before.

    Well, there are two conclusions I can draw:
    1) Most obvious of all is that the xover on the MJA Pro50 is very gentle to the point that it only seriously starts to roll off about 50Hz above the xover frequency.
    2) The bass management in the Marantz, when presented with an non-ideal configuration is cr@p.

    Sorry about the long post. Hope it helps some of the rest of you with the Pro50 maybe get more from your setups.

    Michael.
     

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