Subwoofer Delay Taper (Update 1)

Here is a quick preview of my next post.  These plots contain concentric circles. Each represents a wavelength traveled from the speaker at 125 Hz (2.73 meters). The first one shows 7 speakers spaced at 1/2 wavelength (1.37m) and all set to 0 ms delay. The concentric are all the same for the 7 speakers and we can see where the beam will go – the top center, where all the speakers are in phase.  The MAPP plot then shows you the result. We can also see where the nulls will be – the areas where the wavelength rings are spread all over.

The second set is the same speakers, same spacing but with a delay taper of .67 ms per box. So it’s   0.0, 0.67,1.33 …..up to 4.00 ms. At this freq this translates to 0, 30, 60, 90….. up to 180 degrees (30 deg per box). In this case the concentric rings are all different – because the delay sets up a different origin timing. (I will explain this better later – this is just a preview)  Where is the beam going to go?   Well it is just as obvious as the 0ms version eh?

all for now……………………….

Here are the answers to Matt’s question about what happens on the back side. It is a mirror image with the reflection going in the direction if the delay ===> Right.

Phase wavelengths in front and behind the array

MAPP levels front and back with delay taper

Here is the same physical setup (67ms delay taper) at 63 Hz. The DELAY is the same (.67ms per box) but the PHASE shift is different – it was 30 deg per box at 125 Hz. Now it is 15 deg per box at 63 Hz.  It will be 7.5 deg per box at 31.5 Hz – (not done yet).  The concentric circles are rescaled to the 63 Hz size and recentered to the 15 degree increments. ( I will explain that later) Suffice to say – THESE CIRCLES ARE NOT A FEATURE OF MAPP. They are insanely (correct wording) detailed Autocad scaled drawings. There were derived by a simple 2304 step process.

This is a work in progress……….

63 Hz with delay taper

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8 Comments on “Subwoofer Delay Taper (Update 1)”

  1. Matt Says:

    Bob,

    I think this is obvious but I wanted to check to make sure. The rear “beam” will shift in the same direction?

    Thanks,

    Matt

  2. 6o6 Says:

    Yes sir. I added pics to the post to show

  3. jdenning1 Says:

    Bob,

    Matt and I were wondering how you made MAPP generate the plots with concentric circles? Thanks a bunch!

    Jeremiah

  4. Matt Says:

    Bob,

    Is MAPP always generating the concentric circles in every plot it creates, and they are turned off in our version?

    Jeremiah and I also started thinking about the implications of delay steering vs. physically moving the subs in a subs in a line situation. If we are delaying/moving them to spread the energy, is one or the other better for controlling the energy behind the line in your experience?

    Thanks for your time!

    Matt

    • 6o6 Says:

      The circles are not a MAPP feature. They are scaled .dxf files created in autocad. As for the answer to benefits of moving subs vs delaying……… stayed tuned. Look at the test pattern circles………. you are getting VERY sleepy……………………very sleepy

      • Matt Says:

        When I finally snapped out of it, my check book and wallet were laying in front of me on the desk…I think I hurt myself.

        You should probably have a disclaimer on all of your posts! Our students are complaining of their heads feeling like they’re going to explode. Have a great day and look forward to the explanation.

        Matt

  5. Matt Says:

    I hear people talk about wavelength spacing for subwoofers. Are people normally referring to the wavelength of 125hz? I’ve seen people use 1/4 wavelength and 1/2 wavelength…. etc.

    When i first saw this i thought…. what wavelength frequency? Because every frequency has a different wavelength.

    Thanks for the info…. Great blog!!


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