Crossing over small mains to OB woofers

[suttondesign]

Hi all. Regular readers of this column will recall that I built Heissmann DXT-Mon-182's recently. I've got great results, but as I introduce them into my system in place of my Linkwitz 521.4's, I want to continue using the Linkwitz open-baffle V-frame bass modules because of their naturalism. The Heissmann have passive crossovers but also run through my DSP engine; the Linkwitz use solely DSP crossovers. The Heissmann sit atop the Linkwitz bass modules, so in essence it's still sort of a full-range setup divided between 2 boxes. So here's the question:

When crossing over a small pair of mains like the Heissmann at the 120hz mark, and apart from level setting, is there anything else I should be thinking about besides 4th-order Linkwitz-Reilly DSP settings? I would have thought phase is not troublesome if the two boxes are stacked, though the voice coils of the Heissmann do sit somewhat forward of the big SEAS LROY woofers.

It seems to me that since all I'm doing is replacing Siegfried's top baffle drivers -- in essence a small main -- I just need to get levels right. I will of course run REW to see if something weird is happening, but I was hoping some smart person(s) in the forum could warn me of other issues.

 

[mcdn]

I think it’s basically an LXStudio setup so far as the sub/bass crossover is concerned? The DXTs are monopoles at 120Hz, as are the LXminis. Like you I prefer to cross around that point as the bass from the dipole modules is just so good. Wavelength is around 3m and well below Schroeder, I wouldn’t sweat phase theoretically as the room will dominate practically.

What I did with my LXStudio setup was to eyeball the RTA in REW with different delays until the XO looked smooth, then do the room EQ.

 

[charlielaub]

If you want to get into the dirty details there are things like different response patterns (monitor is monopole vs LX521 bass bins are dipole) and this will go through cardioid at the crossover frequency, however, do not over think it. Honestly I would just play around a bit with the level and frequency of the crossover point and find the best compromise that sounds good to you. The frequency is relatively low and this combination should not really present any audible problems.

 

[suttondesign]

did just what posters suggested and got a pretty good response on rew after playing around with it. sounds terrific.