Crossover verification

[DTRUTH]

Here is my setup:
Mains: M80s
Freq Resp +/-3db (Hz): 34 - 22 kHz
Freq Resp +3dB- 9dB (Hz): 25 - 22 kHz

Center: VP150
Freq Resp +/-3db (Hz): 85 - 22 kHz
Freq Resp +3dB- 9dB (Hz): 50 - 22 kHz

Surrounds: QS8s
Freq Resp +/-3db (Hz): 95 - 22 kHz
Freq Resp +3dB- 9dB (Hz): 65 - 22 kHz

SUB: EP500

I've read Clint's doc on setting crossover freqs and I wanted to make sure I'm interpretting my speaker specs and what I have set correctly.

I'm using the info above in bold to base my crossover settings on. Is that the correct set?

Right now, I have my crossover settings as follows:

Mains: large 40Hz
Center: small 120Hz / 100Hz (Still tweaking)
Surrds: small 100Hz
Sub: *mains+LFE 60Hz (sub set to bypass)

*• When this option is selected,
a full-range signal will be sent to the front
left/right “main” speakers, and the subwoofer will
receive LFE information and the bass frequencies
under the selected crossover point.

If I switch the mains to small and leave them at 40Hz, I can't tell a difference. So, what is the difference between setting to mains to large/small if you are sending everything below the crossover point to the sub? Is there a particular movie or CD to test with that would make changes more noticeable? (I haven't used the Avia disk yet as there is a long wait for it on Netflix. )

Thanks,
DTruth

 

[MDS]

Setting a speaker to large means it gets a full range signal and in the normal case none of the bass for those channels will go to the sub.

With lfe+main, the sub ALSO gets a copy of the bass that is sent to the mains. Onkyo calls that setting 'double bass' and that is a bit more descriptive of what actuallly happens - you have the subwoofer reproducing the bass from the mains (as well as bass below the xover from the Small channels) and you have the mains reproducing that bass as well.

 

[DTRUTH]

Setting a speaker to large means it gets a full range signal and in the normal case none of the bass for those channels will go to the sub.

With lfe+main, the sub ALSO gets a copy of the bass that is sent to the mains. Onkyo calls that setting 'double bass' and that is a bit more descriptive of what actuallly happens - you have the subwoofer reproducing the bass from the mains (as well as bass below the xover from the Small channels) and you have the mains reproducing that bass as well.

With the settings that I have now, the only overlap that falls under "double bass" would be between the 40Hz and 60Hz, correct?

If I have the mains set to small, then what freq range isn't being sent to them? I thought that the speaker would get everything above the crossover point.

 

[annunaki]

The speakers do get everything above a crossover point, if on a highpass crossover. The opposite is true for a lowpass crossover.

By setting your mains to small, the bass will rolloff at 12db/oct.(or 24db/oct. depending upon your receiver) from 40 hz. What that means, is that at 20hz (one octave below the cutt off freq.) the signal present at the speaker will be 12db quieter than it is at 40hz. If your speakers are ported, and you have them at high volumes, this could potentially damage a driver if the output level was high enough.

I would suggest setting all of you speakers to small. The mains with the 40hz crossover point, the center at 90hz or 100hz and your surrounds at 100hz. The sub should then be sent signals below 40hz.

However, you may want to try the main's crossover at 60hz and the sub at 60hz. This may help to blend the rest of the speakers a little better.


I am not impressed with the limited low end capability of the Axiom surrounds and center speakers. I think they should go down to at least 80hz.

 

[DTRUTH]

The speakers do get everything above a crossover point, if on a highpass crossover. The opposite is true for a lowpass crossover.

By setting your mains to small, the bass will rolloff at 12db/oct.(or 24db/oct. depending upon your receiver) from 40 hz. What that means, is that at 20hz (one octave below the cutt off freq.) the signal present at the speaker will be 12db quieter than it is at 40hz. If your speakers are ported, and you have them at high volumes, this could potentially damage a driver if the output level was high enough.

I would suggest setting all of you speakers to small. The mains with the 40hz crossover point, the center at 90hz or 100hz and your surrounds at 100hz. The sub should then be sent signals below 40hz.

However, you may want to try the main's crossover at 60hz and the sub at 60hz. This may help to blend the rest of the speakers a little better.


I am not impressed with the limited low end capability of the Axiom surrounds and center speakers. I think they should go down to at least 80hz.

Thanks! That helps a lot.

 

[eric0531]

Isn't using a crossover of 40Hz a little low? My understading is that you want the speaker to be able to handle frequencies for a least an octive below the crossover point to allow for a smooth transition from speakers to subwoofer.

Here's a very good article over on ecoustics.com about bass management:
http://forum.ecoustics.com/bbs/messages/34579/128214.html

 

[MDS]

Setting the xover to 1/2 to 1 octave above the F3 point of the least capable speaker is a good rule of thumb; however, it breaks down when you have satellites that are only good to 100 Hz or higher. Using the rule your xover would be 150 to 200 Hz which is way too high as the bass could become localizable (you can tell it is coming from the sub).

The best you can do in that case is set the xover right at the F3 point. The eCoustics article summed up the relevant issues pretty succinctly.

 

[aarond]

here is another good bass management article http://www.hometheaterhifi.com/volume_12_2/feature-article-slope-troubles-6-2005.html

 

[MACCA350]

Ask yourself which can handle the bass the best. If your sub can handle bass from say 20hz - 60hz or 80hz better then your mains(in most casses it will), then you'd be better off raising your xover.

cheers