What crossover frequency to set?

[underthebridge]

Hi everyone. After lurking for quite a while, I finally decided to post something .

Anyway I am setting up the HT system in my brother's house, which has an in-wall 7-channel setup preinstalled. The speakers are Sonance Cinema Select, which are supposedly THX Select certified. After looking at the specs (http://www.sonance.com/subs/product_details_specs.php?product_id=327), the frequency range is quoted as:

80Hz - 20kHz, +/-3dB

I am hooking these speakers up to a Marantz SR8500 THX receiver. The receiver allows you to set the low-pass crossover frequency to 80Hz, 100Hz, or 120Hz. I would like to use the receiver as an active crossover (i.e. using LFE output). The subwoofer is a Velodyne DLS-4000R.

I know that the recommended setting for THX is 80Hz, and I would love to set the Xover at this point but it just worries me how 80Hz is right at lower boundary of the speaker response. Should I do it anway (after all, the speakers are THX certified and are designed with 80Hz crossover in mind, no?). Or maybe 100Hz is a safer deal?

Also, should I bypass the built-in subwoofer crossover entirely?

Thanks.

 

[Vancouver]

I asked a similar question here. While my speakers are slightly different I am sure you could read between the lines. I would guess at setting it at 100Hz.

http://forums.audioholics.com/forums/showthread.php?t=12625

 

[Takeereasy]

I think that the odds are Vancouver is correct, but...
If those speakers are THX certified then they are supposed to have sufficient output at 80hz. What you really need to do is pick up a DVD such as AVIA or S&V HT setup Disc. They provide you a test tone so that you can measure how well the speakers blend in with the sub. If you have the crossover too low then there will be a gap in the sound, or there will be less volume at the frequency where the speakers sound cuts out and the sub can't reach. You can grab the Sound & Vision disc for about $20 on Amazon. It's actually kind of fun to go through the first time. Not so much the third time though.

 

[MACCA350]

Use a low frequency sweep(found in AVIA or Digital Video Essentials DVD's) to help you find the best setting for your system. If you dont have these mabey the THX Optomiser(found on THX Mastered DVD's) could help.

Cheers

 

[AVRat]

Set at 80Hz and bypass the sub crossover. Even with a 12dB/octave slope, the speakers are still producing sound at 50Hz.

 

[underthebridge]

Thanks for all your replies. I will try 80Hz and see how it turns out.