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Thread: Plugging port hole in Sierra 2 center that's in a cabinet?

  1. #1

    Default Plugging port hole in Sierra 2 center that's in a cabinet?

    I have LRC S2's and the center is in a Sanus media cabinet like below. I could hear the center sounding kind of boxy and felt like the sound was bouncing around inside the cabinet. So I put a small roll of acoustic foam in the back vent as a plug and it seems to sound better.

    Any better options? Maybe just putting a 12" x 24" piece of foam around the back of the speaker, but a few inches behind and not blocking the hole? I didn't have a piece to try.

    http://www.sanus.com/assets/products...b_LS_570px.jpg

  2. #2

    Default Re: Plugging port hole in Sierra 2 center that's in a cabinet?

    Is it crossed over to a sub? Is the speaker at all recessed into the cabinet? Can you remove the center face of the cabinet to see if maybe it is contributing?

    I have my Sierra 2 center is a similar shaped salamander cabinet, crossed at 80hz, door off with the speaker angled slightly up and extending slightly out of the cabinet. I don't hear anything boxy or any bouncing around in the cabinet. It sounds like the LRs.
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  3. #3
    Join Date
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    Default Re: Plugging port hole in Sierra 2 center that's in a cabinet?

    I took some measurements of my Sierra-2 running full range with and without the port plugged. This was with the speaker sitting on a speaker stand, microphone at my couch, and all room correction turned off.


  4. #4

    Default Re: Plugging port hole in Sierra 2 center that's in a cabinet?

    Yes, I think it's crossed at 80. I had it in a config like yours but then put the door back on and have it recessed a bit. The door has a thin metal grill. I just liked how it looked better. Maybe I'll try it again though.

  5. #5

    Default Re: Plugging port hole in Sierra 2 center that's in a cabinet?

    Cool graph. What software and setup do you use to capture that?

    What's the chart look like with room correction on?

    Thx!

  6. #6

    Default Re: Plugging port hole in Sierra 2 center that's in a cabinet?

    Maybe I spoke too soon about not being boxy. Center does have a decent peak at around 80 Hz. Maybe the correction is fixing any boxy sounds???

    Edit: Are these ARC graphs with Anthem provided mic anywhere close to what I'd get with REW and a real mic? ... This rabbit hole looks pretty deep.
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    Last edited by Todd WI; 02-10-2017 at 06:33 PM.

  7. #7
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    Default Re: Plugging port hole in Sierra 2 center that's in a cabinet?

    Quote Originally Posted by Blingleberry View Post
    Cool graph. What software and setup do you use to capture that?

    What's the chart look like with room correction on?

    Thx!
    I'm using Room EQ Wizard with a Umik-1 microphone. I'll see if I can dig up the room corrected measurement.

  8. #8
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    Default Re: Plugging port hole in Sierra 2 center that's in a cabinet?

    Quote Originally Posted by Todd WI View Post
    Maybe I spoke too soon about not being boxy. Center does have a decent peak at around 80 Hz. Maybe the correction is fixing any boxy sounds???

    Edit: Are these ARC graphs with Anthem provided mic anywhere close to what I'd get with REW and a real mic? ... This rabbit hole looks pretty deep.
    That 80Hz peak is only +4dB, typical in-room peaks are +/- 10dB or higher. This is actually a fantastic in-room response, esp when considering the placement. The peak is also more likely caused by floor bounce than the enclosure the speaker is placed in.

    Plugging the port reduces the peak because it reduces the bass response of the speaker. The better option is to use auto-eq.
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    Good Sound To You!

    David Fabrikant
    www.ascendacoustics.com

  9. #9

    Default Re: Plugging port hole in Sierra 2 center that's in a cabinet?

    Thanks for the info Dave!

    I was curious what the frequency graph would look like with the center speaker recessed into the cabinet. In the graph below, the blue line is with the speaker in the normal position angled up and at the front of the cabinet, the red line is with the speaker flat and recessed 4 inches into the cabinet. I guess I expected to see bigger differences.
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  10. #10
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    Default Re: Plugging port hole in Sierra 2 center that's in a cabinet?

    Quote Originally Posted by Todd WI View Post
    Thanks for the info Dave!

    I was curious what the frequency graph would look like with the center speaker recessed into the cabinet. In the graph below, the blue line is with the speaker in the normal position angled up and at the front of the cabinet, the red line is with the speaker flat and recessed 4 inches into the cabinet. I guess I expected to see bigger differences.
    80Hz has a wavelength of 14 feet. Moving the speaker a few inches will have no effect on these long wavelengths - as you can see. The differences in your positioning is evident in the critical 1kHz - 3kHz range and I definitely recommend the "blue line" positioning, where the speaker is not recessed into the cabinet.
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    Good Sound To You!

    David Fabrikant
    www.ascendacoustics.com

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