| Small speaker flanking sub limitations. [message #83791] |
Wed, 26 October 2016 15:08  |
jonone
Messages: 67
Registered: October 2015
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Viscount |
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So my main speakers are quite small typical 6" plus 1" dome tweeter. I know the idea of running your mains full range with flanking subs is to have as many speakers overlapping as possible to help smooth the response.
But if your speakers are relatively small is there some actual benefit in crossing them over at 80hz etc like the AV boys do, does this increase "headroom" or just intermod distortion?
Is intermod distortion audible?
Is it plausible to roll in the flanking subs with the circa 100hz crossover but then add a 80hz shallow crossover to your mains, this way the modal transition area is still covered by the mains and the flanking subs.
If you also have distributed subs you still have up to four sources overlapping up to 80hz. (Three in my case)
I suppose you can measure the response at the seating positions and see how adding in or taking out the 80hz crossover on the mains effects the response?
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| Re: Small speaker flanking sub limitations. [message #83798 is a reply to message #83791] |
Thu, 27 October 2016 08:42  |
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Wayne Parham
Messages: 18783
Registered: January 2001
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Illuminati (33rd Degree) |
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When mains are very small like that, you really need to use subs just to prevent over-excursion of the mains. If you want to use a flanking sub approach in that case, you really need two subs per side.
The whole idea is to increase the number of sound sources in the modal region. This smooths room modes and self-interference notches. At low frequencies, smoothing is accomplished by placing subs around the room, distant from one another. At higher frequencies, where localization can occur, you want the sound sources closer together, but still not coherently grouped (like you would want in an anechoic environment).
The idea behind flanking sub placement is basically the same as an array. It reduces self-interference notches from nearest boundaries. At whatever frequency one sound source suffers a notch, the other won't and vice-versa. Since you tend to see these anomalies in the 100-200 Hertz region, blending of sound sources by a truncated array makes sense.
That's why we run helper woofers (flanking subs) up into that 100-200Hz range. They smooth self-interference and high frequency room modes, up to around 200Hz where the sound field becomes statistical rather than modal.
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