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Bass port whistle on my Sequels

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Tube60

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Hi all
Both my Sequels will get a bit of a whistle or "chuffing" with recordings that go down really deep. The tone controls on my preamp are set flat, in fact, I've cut the bass about 3db to suit the room acoustics anyway. Normally this is not a big deal, but as recording bandwidth increases, musicians are making more use of really low frequencies, so this is happening more often. I've considered replacing the stock ports with flared ports, but so far I haven't found any close to the stock inside diameter. Has anyone else run into this? If so, any suggestions?
Thanks & regards,
Ross
 

roberto

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Tube60 said:
Hi all
Both my Sequels will get a bit of a whistle or "chuffing" with recordings that go down really deep. The tone controls on my preamp are set flat, in fact, I've cut the bass about 3db to suit the room acoustics anyway. Normally this is not a big deal, but as recording bandwidth increases, musicians are making more use of really low frequencies, so this is happening more often. I've considered replacing the stock ports with flared ports, but so far I haven't found any close to the stock inside diameter. Has anyone else run into this? If so, any suggestions?
Thanks & regards,
Ross
Hola Ross, just thinking loud...if you have too much bass energy is because you have weak panels, in other words, the bass is more present than it should...I do understand your point regarding the musicians with more low frequency usage...but your speakers should not whistle...perhaps this might help...happy listening,
Roberto. :eek:
 

Tube60

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roberto said:
Hola Ross, just thinking loud...if you have too much bass energy is because you have weak panels, ...I do understand your point regarding the musicians with more low frequency usage...but your speakers should not whistle...perhaps this might help...happy listening,
Roberto. :eek:
I hadn't considered weak panels, however the panels on these have very few hours on them, and the transition from panel to dynamic is very smooth; not quite seamless, but close. And it's definitely the bass port. I played my copy of Boston Acoustic's Bass Rally Collection , disc one, track two, which has subsonic information in the recording, and the whistling and "chuffing" is really pronounced, and that allowed me to isolate the issue. Of course, not all recordings have subsonics, and I was definitely exaggerating the problem!
I wonder if a very light stuffing of the port would help, using Acousta-Stuf or pillow stuffing; just enough that it doesn't collapse from it's own weight?
 

MiTT

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I used to think I was getting some intermittent bass port chuffing from my ReQuests, but then it dawned on me that it only manifested itself when I had eaten a great abundance of Mexican food. Further research led me to discover the true source of the abnormality and it was easily resolved by placing a pillow beneath the offending "port", thus greatly diminishing the noise. This remedy did not work for all of the senses unfortunately.

On a more serious note - yes, I believe that some soft material placed into the ports should help with your issue.

Mine is an entirely different situation...the upside of course is that I am left alone to enjoy the sweet spot to the fullest.
 

Statman

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Tube 60

Okay am I missing something here? I own Sequel II's and they have no "port",they are a sealed box system? Did the original Sequels have a ported woofer section? You say the "tone controls are flat"? What pre amp are you using? Any chance you have a subsonic filter on the "preamp"? You can stuff the ports but that will also change the characteristics of the bass.
 

Joey_V

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Port turbulence is evident when you're pushing the sub beyond it's potentially musical limits... too much air movement for the size of the chamber will result in a rapid "flush" of air out of the port..... thus, port turbulence.

You can soften the port with some materials... but you would likely change the sonic character of the bass, so YMMV.

Or maybe you're driving the bass aspect of your stats too much, weak panels or an unbalanced eq would be the likely culprits.

Joey
 

Tube60

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Statman said:
Tube 60

Okay am I missing something here? I own Sequel II's and they have no "port",they are a sealed box system? Did the original Sequels have a ported woofer section? You say the "tone controls are flat"? What pre amp are you using? Any chance you have a subsonic filter on the "preamp"? You can stuff the ports but that will also change the characteristics of the bass.
I've never looked closely at the IIs, so I didn't realize they had a sealed enclosure. The vent port on the original Sequel is below the woofer, and it's about 1 1/2" in diameter.
My preamp is a restored and mildly hotrodded McIntosh MX-110. It has a low frequency cutoff, but it's set to 60hz for turntable rumble.
I'll try padding the ports, but I think that'll change the sonic characteristics like you and Joey_V have mentioned. I'll continue in the meantime trying different adjustments and tweaks to the system.
I'm still of the opinion that the panels are not weak on these. They play loud and don't have any odd frequency imbalances, and the panels don't have many hours on them. I think it's a combination of really low frequencies in many recordings today, I love bass, and my Citation II is capable of reproducing very low frequencies ( down to 7hz according to the mfr ). That and it's got loads of headroom, so it'll dump it's plate dissipation into almost any frequency & impedance without sweating too much!
Okay, I'll stop bragging now! :rolleyes:
Anyway, thanks for the advice and observations so far.
Regards,
Ross
 

roberto

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Tube60 said:
I've never looked closely at the IIs, so I didn't realize they had a sealed enclosure. The vent port on the original Sequel is below the woofer, and it's about 1 1/2" in diameter.
My preamp is a restored and mildly hotrodded McIntosh MX-110. It has a low frequency cutoff, but it's set to 60hz for turntable rumble.
I'll try padding the ports, but I think that'll change the sonic characteristics like you and Joey_V have mentioned. I'll continue in the meantime trying different adjustments and tweaks to the system.
I'm still of the opinion that the panels are not weak on these. They play loud and don't have any odd frequency imbalances, and the panels don't have many hours on them. I think it's a combination of really low frequencies in many recordings today, I love bass, and my Citation II is capable of reproducing very low frequencies ( down to 7hz according to the mfr ). That and it's got loads of headroom, so it'll dump it's plate dissipation into almost any frequency & impedance without sweating too much!
Okay, I'll stop bragging now! :rolleyes:
Anyway, thanks for the advice and observations so far.
Regards,
Ross
Hola Ross...well, I was just thinking loud regarding of the might and possible weak panels...why? I had notice that when I had changed panels, the bass at the room overall is less present, due to the high sensitive of the newer panels, in other words, new panels sound louder than old ones...making this feature to bring down a bit the bass energy present in the room. I did have your problem with a pair of Sequels, too much bass energy in the room, and the panels sounded to the ears o.k., but they were with less sensitivity, making the woofers to sound louder than the panels...it is good to know that your panels are o.k... happy listening,
Roberto.
 

Tube60

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*update*

Over the weekend I moved the speakers a little further apart and further away from the wall (three feet from the panels vs. 2 1/2) which has helped a whole bunch. I think the problem has been some standing wave reinforcement in the low frequencies. To get the chuffing and whistling to happen now, I have to get the amp well into A/B, and at that point, the system is playing a lot louder than even I like it, so the problem is effectively solved. However the change in location has revealed more clearly some issues I need to address with my preamp; specifically the volume control is mistracking pretty badly, so it's time to upgrade to a Goldpoint attenuator. That and I want to re-do the tone control circuits with better quality components. And I thnk some bass traps in the room will help.
Anyway, thanks to all for the advice!
Regards,
Ross
 

Craig

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I could use some bass traps as well. I've been using pillows everywhere and I hear a noticeable effect when I have enough tucked away in the corners and along the bassboards. My room begins to sound good in the bass region with the pillow tweak along with an increase in the Summits bass control knobs. Better bass control in the room allows you to turn up the bass on the Summits and let you hear what they are capable of. Time to put the pillows back and get some real bass traps for the room.
 

Peter Hogan

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Craig said:
If this decay time, known as the room's reverberation time, is too long, sounds will linger within the space and begin to overlap with new sounds being made, creating an unintelligible caucauphony.
Hi,
One of the places I have known this to be very true is at indoor pools. You have the reflective surface of the water, and most of the floor/walls tend to be tile, also very reflective.

I used to work for a company that made underwater communications equipment (sort of like walkie talkies for scuba divers). When demoing the equipment in open water, the sound was extremely intelligible, but when doing a demo in an indoor pool, the sound on the surface unit was MUCH less so, due to the effects you describe. In that case, we used headphones, and the sound quality returned...:).

Peter
 
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