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Re: Mono "flanking sub" [message #83336 is a reply to message #83335] Wed, 10 August 2016 15:01 Go to previous messageGo to next message
Wayne Parham is currently offline  Wayne Parham
Messages: 18670
Registered: January 2001
Illuminati (33rd Degree)

When we talk about phase anomalies (time domain) or when we talk about peaks and dips in the amplitude response (frequency domain), we're essentially talking about flip sides of the same coin. I've always been more focused on the frequency domain because I know that anomalies in frequency response are audible, when the peaks or dips are large and wide enough. Anomalies in the time domain are a little more controversial, unless the defects are large enough to cause a time delay between two sounds that were supposed to be simultaneously presented. But again, the two things are really inter-related, and problems in the time domain are presented in the frequency domain, and vice-versa.

Beyond that, see the Pi Speakers FAQ, and especially the sections about Crossovers, Room Effects and Loudspeaker Interactions and Simulations and Measurements. They talk a lot about what is required to get proper summing between adjacent subsystems. This will address what you asked "how important you feel phase is between the drivers in a speaker?" They also talk a lot about room interactions, room modes and the ways to correct the problems that result. That will answer your questions about flanking subs and the frequency range they're used in.

In a nutshell, it is important to get summing right in the statistical range, above 200Hz. This is what you're calling "phase between drivers." We want them to act as a single point source. On the other hand, it is impossible to do this in the modal range, below 200Hz, because of the multiple reflections from each room boundary. Since we can't achieve a point source in the modal region, we want dense interference to smooth the sound field instead.

Re: Mono "flanking sub" [message #83340 is a reply to message #83336] Thu, 11 August 2016 08:00 Go to previous messageGo to next message
jonone is currently offline  jonone
Messages: 67
Registered: October 2015
Viscount
Ok thanks I will have a read.
Great simple explanation at the end of the post though? Smile

I know I've asked this before and you have said its not that important but is there a specific filter type you use and a xo point you reccomend for flanking subs or is it room / speaker dependent? What do you use in your own set up?

Is there a technique to best choose the filter and xo?

Also should the subs be a certain db down (I.e 6db or somthing) at 200hz to help the speakers be the point source above 200hz?

P.s I've ordered another td15h+ from ae to make steps towards a true flanking sub setup.
Re: Mono "flanking sub" [message #83341 is a reply to message #83340] Thu, 11 August 2016 08:40 Go to previous messageGo to next message
Wayne Parham is currently offline  Wayne Parham
Messages: 18670
Registered: January 2001
Illuminati (33rd Degree)

The links in the FAQ explain all that and more.

Re: Mono "flanking sub" [message #83342 is a reply to message #81624] Thu, 11 August 2016 14:54 Go to previous messageGo to next message
jonone is currently offline  jonone
Messages: 67
Registered: October 2015
Viscount
Something I found.

"Low-pass frequency for flanking subs should be between 80Hz and 150Hz, and use second-order or third-order for best results. Fourth-order can be used, but it doesn't sound as good to me - It doesn't blend as well. The higher the slope, the higher the the crossover frequency. So for example, second-order at 90Hz or 100Hz often works well, third-order is better around 125Hz and fourth-order usually has to be set higher still. Set the amplitude for SPL matching the mains in the overlap band."
Re: Mono "flanking sub" [message #83753 is a reply to message #81624] Fri, 21 October 2016 12:52 Go to previous message
jonone is currently offline  jonone
Messages: 67
Registered: October 2015
Viscount
My new woofer has arrived, so I can use them as flanking subs, I've also had some new cabs made so they will be forward firing this time.
The Amps ordered and the cabs are being sprayed, so I'm pretty much ready to rock.

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