My monitor audio vector vw-8 subwoofer puffing air at low frequencies - AVS Forum
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post #1 of 9 Old 08-30-2013, 10:28 AM - Thread Starter
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I have a monitor audio vw8 sub connected to a marantz sr5005 receiver.
I have a question: Should my subwoofer try and produce lower frequencies than it was designed to or is my unit faulty? This is most noticeable while watching movies with a LFE track: at above 30hz everything is fine, but the sub tries to go lower than this only to produce puffing air sounds which are annoying to the ear. Shouldn't the sub have an internal crossover for the lowest frequencies so it would cut anything it can't handle?
I used this for testing: http://www.audiocheck.net/testtones_subwooferharmonicdistortion.php. Even at 10hz the sub tries to reproduce the frequency. Is this normal?
Thank you.
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post #2 of 9 Old 08-30-2013, 03:48 PM
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That depends entirely upon how MA implemented the protection mechanisms. Some companies are very particular about how they program their DSP's and HPF's, others are less concerned. It's not terribly uncommon for a ported sub to make some unpleasant sound when pushed, but most companies try and minimize it.

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post #3 of 9 Old 08-30-2013, 07:07 PM
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Quote:
Originally Posted by Andrei Pavel View Post

Even at 10hz the sub tries to reproduce the frequency. Is this normal?
It's normal if the amp driving it is not high-pass filtered to prevent the passage of frequencies lower than it it can effectively reproduce. All powered subs should have high pass filters built in, but not all do.

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post #4 of 9 Old 08-31-2013, 05:06 AM - Thread Starter
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I have discovered that by blocking its bass-reflex port this problem goes away. The only downside seems to be the lower output volume. The result is a much more enjoyable experience. However, is there a chance to damage the subwoofer by sealing its port?
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post #5 of 9 Old 08-31-2013, 06:30 AM
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Quote:
Originally Posted by Andrei Pavel View Post

I have discovered that by blocking its bass-reflex port this problem goes away.
That's because air vibrating in the port is the source of the chuffing.
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The only downside seems to be the lower output volume.
That's because by blocking the port you're restricting the cone's ability to move, and when you do that you lose output and low frequency extension.
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However, is there a chance to damage the subwoofer by sealing its port?
There is. You've addressed the symptom, but not the cause, which is most likely an amp that's not high passed. High passing prevents the low frequencies that the speaker can't handle from being amplified. While blocking the port helps with the driver over-excursion, those low frequencies are still being amplified and sent to the driver, and all of the power associated with them is still heating the voice coil, with long term heat damage a distinct possibility.

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post #6 of 9 Old 08-31-2013, 06:57 AM
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Quote:
Originally Posted by Andrei Pavel View Post

I have discovered that by blocking its bass-reflex port this problem goes away. The only downside seems to be the lower output volume. The result is a much more enjoyable experience. However, is there a chance to damage the subwoofer by sealing its port?

I would advise against that. Some manufacturers engineer their subwoofers to accommodate various tuning frequencies by blocking one (or more) ports, but those have been specifically designed for that. If yours hasn't been -- and I doubt it was -- there's a strong likelihood of damage. If the port noise is happening on a regular basis it might be time to consider another sub.

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post #7 of 9 Old 09-03-2013, 04:25 PM - Thread Starter
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I decided to replace the subwoofer. I found a second-hand MA silver RSW12 for about 400 euros. The reviews are good and I don't think that there is a difference between this one and the new model besides design (the new one retails in my country for aprox 800 euros). It has a sealed cabinet which means there is zero chance of port chuffing.
Do you think it is a good fit for my system: Marantz SR 5005, 2x MA BX6, 4x MA vector satelites and 1x MA vector centre?
This is the subwoofer in question: http://www.okazii.ro/boxe/altele/subwoofer-monitor-audio-rsw12-a127188052?icid=homepage-carousel&ibid=ultimele-accesate[127188052]
Thank you for all your informative and fast replies.
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post #8 of 9 Old 09-03-2013, 06:17 PM
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I like MA speakers, but I've never heard any of their subwoofers. If it's in good shape that might not be a bad deal.

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post #9 of 9 Old 09-03-2013, 10:02 PM
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A 12" 500 watt RMS sealed subwoofer vs an 8" 100 watt RMS ported? Most likely it will have a good bit more output. Probably better sound quality, too.

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