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Thread: Sierra2 port chuffing

  1. #1
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    Default Sierra2 port chuffing

    I've been away from home for work about 1 week and the first thing I did when I got home was fire up the HiFi. To my horror the 2nd track I listened to had this odd noise. I initially thought something was rattling on a shelf but it seems to be coming from the ports. I don't really recall hearing it before I left but I'm getting significant noise from the ports. I'm pretty sure it's due to the air turbulence of the port which I believe is text book "Chuffing"?

    The track was "It Could Be Sweet" by Portishead, which is very bass centric. I don't really notice it with other tracks.

    In total disclosure, the day before I left I was doing some measurements and messing with subwoofer phase. I had played Pink noise and set volume to ~85db. I then played a 50hz sine and adjusted the sub phase until reading the highest SPL at the listening position. I definitely heard significant port noise while performing my measurement but I kind of just wrote it off due to the sine wave.

    I also spent some time setting a PEQ on the sub to help tame the room mode @ 55hz, I unfortunately have no way of doing anything for the mains at the moment.

    All of my amp's tone controls are bypassed via a "pure" switch on the amp.

    I didn't really get a chance to evaluate anything I was doing before having to leave town.

    Anyone else able to evaluate this track and notice anything....?
    Could I have damaged something by playing a sine wave for an extended period?
    Could the room mode be contributing to the noise?

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  2. #2
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    Default Re: Sierra2 port chuffing

    I don't have that track, but if you're getting odd noises like that I'd suggest you need to back it off a little.
    My Sierra 2's are driven by a Parasound Halo A21 with 250 wpc on tap. I've never heard any kind of port noise. These are quality speakers, but every speaker has its limits.

  3. #3
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    Default Re: Sierra2 port chuffing

    First...are you sure it isn't some anomaly in the track itself...bad recording?

    Second...are you sure the noise is coming from the port? The port on the Sierra-2 is quite large and flared, hard to believe it can be chuffed without turning the volume up very high. I demo'd a pair at Ascend, no sub, to some crazy high levels with The Sheffield Lab: Drum and Track disc with no sign of chuffing or distress.

    When driven full-range, I have not heard issues like that from my Sierra-2's.

    Room node at 55hz? You should not fix nulls by EQ, only peaks. If you turned the PEQ up at 55hz, I bet that is your problem. Oops...nevermind, that was for your sub only.

    I'm assuming you are crossing over to the sub at 50hz...why so low? I cross at 80hz.
    Last edited by curtis; 04-01-2016 at 09:50 PM.
    -curtis

  4. #4
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    Default Re: Sierra2 port chuffing

    OK...I played the track off of Tidal.

    Definitely moves air, but no chuffing...I had it pretty loud at full-range.

    I am wondering if your room is accentuating the frequency and making it sound bad...like chuffing.
    -curtis

  5. #5
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    Default Re: Sierra2 port chuffing

    Quote Originally Posted by sharkman View Post
    My Sierra 2's are driven by a Parasound Halo A21 with 250 wpc on tap. I've never heard any kind of port noise.
    I don't have any where near that amount of power on tap, 100wpc @ 8ohms Yamaha A-S801.
    Maybe I'm not familiar with what real chuff is, but if I put my fingers in the port the noise changes or goes away.

    Quote Originally Posted by curtis View Post
    First...are you sure it isn't some anomaly in the track itself...bad recording?
    Second...are you sure the noise is coming from the port?
    Room node at 55hz? You should not fix nulls by EQ, only peaks.
    I'm assuming you are crossing over to the sub at 50hz...why so low? I cross at 80hz.
    It might just be something weird with that track. I added a link to spotify incase anyone wanted to check it out.

    I actually have the crossover set to max but have the LPF on the sub set to 50hz/24db Rythmik F12. 80hz seems pretty high unless you have some sort of HPF. Are you running full range with your Sierra2? I figure the sub is just there to fill in where the Sierras start to lay down.

  6. #6
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    Default Re: Sierra2 port chuffing

    Quote Originally Posted by SAFETYpin View Post
    I actually have the crossover set to max but have the LPF on the sub set to 50hz/24db Rythmik F12. 80hz seems pretty high unless you have some sort of HPF. Are you running full range with your Sierra2? I figure the sub is just there to fill in where the Sierras start to lay down.
    Yeah...I am running a HP (but did fullrange to test the track). No need to stress the Sierra's woofer/low end if you don't have too...and bass is cleaner from the Rythmik.
    Last edited by curtis; 04-01-2016 at 10:34 PM.
    -curtis

  7. #7
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    Default Re: Sierra2 port chuffing

    Maybe there is something different with the Spotify track.

    That Yamaha is nice...feed it some high quality source.
    -curtis

  8. #8
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    Default Re: Sierra2 port chuffing

    Quote Originally Posted by curtis View Post
    That Yamaha is nice...feed it some high quality source.
    I can't hear a difference between 320kbps Vorbis and FLAC, so I'm not terrible worried about it.

    I was able to capture the sound on my phone. YouTube This was recorded roughly 3-4in. away from the port and off to the side of it and at ~2:15 in the track. Playback volume was peaking around 93db according to an app on my phone, I didn't bother getting the measurement mic out.

    That flutter/port noise is pretty prominent on this track. The phone did a good job picking up the noise, IMO. I'm getting this on both speakers so if it is damaged somehow, I managed to do it to both.

  9. #9
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    Default Re: Sierra2 port chuffing

    That certainly doesn't sound like port noise or what I hear from my speakers.

    Can you reproduce something like it with other music?

    93db peaks are not extremely loud...but the SPL/FR apps on the iPhone are not accurate...although for this application it should be fine.
    -curtis

  10. #10
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    Default Re: Sierra2 port chuffing

    I can recreate it with REW and a sine wave, I don't notice it in other tracks as much. I was incorrect at the spl levels I was using during my phase adjustment. It was probably closer to 90db with pink noise and then playing a 50hz sine. If I recreate this scenario I can start to hear the noise at ~63-60hz but it gets louder as I drop the frequency, and starts rolling off ~45hz.

    50hz sine 90db video
    Hand near port 50hz sine

    Another track I notice it in.... "Never End Land" by Infected Mushroom very noisy around 1:10
    Last edited by SAFETYpin; 04-02-2016 at 10:47 AM. Reason: Added 2nd video

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