Sierra2 port chuffing

[SAFETYpin]

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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[sharkman]

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.

[curtis]

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.

[curtis]

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.

[SAFETYpin]

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.

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.

[curtis]

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.

[curtis]

Maybe there is something different with the Spotify track.

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

[RicardoJoa]

Make sure is not the damping material that is vibrating inside the cabinet

[davef]

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.

This was really a bad idea... Sine Waves are not music, they are steady state and heat up voice coils very quickly. 50Hz also happens to be where the port is tuned and as such, this is where the woofer has minimal movement so the voice coil has the least amount of cooling (nearly all output at this frequency is from the rear port)

With setting the level to 85dB using pink noise, it is highly likely that 50Hz could be -10dB or even more depending on your room modes. If you were measuring SPL at 10 feet back, you were hitting the speakers with a 100watt 50Hz sine wave. Frankly, I am surprised the woofer coils didn't completely burn up.

It is highly likely you damaged the woofers but please answer these questions.

1. How far back were you sitting when you measured the SPL?
2. What did you use to measure the SPL and what weighting?
3. When you hear this noise, is it only this particular song?
4. Are you running the speakers full range?
5. Did you send the sine wave to both speakers at the same time or one speaker at a time?
6. What amp or receiver are you using?

And most importantly -- please stop hitting the speakers with sine waves

Also, please feel free to send me an email directly.

Thanks in advance!

[SAFETYpin]

This was really a bad idea... Sine Waves are not music, they are steady state and heat up voice coils very quickly. 50Hz also happens to be where the port is tuned and as such, this is where the woofer has minimal movement so the voice coil has the least amount of cooling (nearly all output at this frequency is from the rear port)

With setting the level to 85dB using pink noise, it is highly likely that 50Hz could be -10dB or even more depending on your room modes. If you were measuring SPL at 10 feet back, you were hitting the speakers with a 100watt 50Hz sine wave. Frankly, I am surprised the woofer coils didn't completely burn up.

It is highly likely you damaged the woofers but please answer these questions.

1. How far back were you sitting when you measured the SPL?
2. What did you use to measure the SPL and what weighting?
3. When you hear this noise, is it only this particular song?
4. Are you running the speakers full range?
5. Did you send the sine wave to both speakers at the same time or one speaker at a time?
6. What amp or receiver are you using?

And most importantly -- please stop hitting the speakers with sine waves

Also, please feel free to send me an email directly.

Thanks in advance!

OH NO!!!!

1. ~8ft to the mic, it's a pretty small room but does have two open doorways to the rest of the house.
2. Umik-1 Z weighting as it's what REW recommended with the USB mic
3. I've noticed this in two tracks
4. Speakers are full range, I don't have any type of HPF with my amp.
5. I don't recall, i've probably done both.
6. Yamaha A-S801 http://usa.yamaha.com/products/audio...s/amps/a-s801/

What is my mistake going to cost me, approximately?