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PM 2.1: rattling noise from subwooofer


TwoCables

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No, the chuffing is so far unfixable. I think that it's just a case of me wanting more out of my subwoofer than it can handle, even though the chuffing is the only problem. I mean, there's no subwoofer driver distortion or anything, just chuffing. If it weren't for the chuffing, then this would be an even MORE impressive sound system. I mean, if I ignore the chuffing (if I pretend that it's not happening) and only listen to the low-end that's being produced and the QUALITY of that low-end, then wow - it's very impressive and very much in my chest and gut. I love it. Unfortunately though, I can't get rid of the chuffing. Fortunately, there aren't many things I listen to or watch that make my subwoofer chuff.

 

After reading about subwoofer cabinet design, I'd probably need to build my own cabinet with a straight tube with a more aggressive flange on the outside (like a horn). Of course, at that point, I'd be better off just building my own system.

 

So, I've decided to live with it and understand that when I hear it, I'm just at the limits of my subwoofer cabinet. So at those times, I just turn the Subwoofer level down until it stops. Fortunately, I never have to turn it down so low that the low-end is too low. However, I would obviously prefer to keep the level up for a more powerful sound, but hey - it's not a $1,000 system either! :)

Edited by TwoCables
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Are you sure it's chuffing? Chuffing does not sound like a rattle at all, it's unique. Can you roll your r's like you were saying arriba in Spanish? Chuffing sounds like you doing that without using your voice. It just sounds like air fluttering or flapping through something. The pressure multiplied by the velocity in a system is a constant when it's linear. You decrease the pressure, and the velocity goes up. This is what happens when you put your thumb on the end of a hosepipe: the pressure has dropped, but the velocity skyrocketed.

 

Chuffing is when the above falls apart and becomes nonlinear. This occurs when the area is too small for the velocity to increase and stay in shape. Think about merging 4 lanes of traffic into 1: you can't break the speed limit to keep the flow of traffic the same, so you get a traffic jam. Chuffing is that traffic jam inside a ported box. Putting tape over the port is just the sound of the tape causing a disturbance, not the port.

 

I would suspect a loose wire hitting a cabinet wall, hitting the port, or the leads on the driver slapping the cone. Again, chuffing is not a "hard" sound like a rattle. It's a fluttering, yet soft sound. Since you've only just now noticed it, I don't think it's chuffing. That would have been there since the first time you played it loudly. Can you confirm if it's soft sounding or hard sounding? That's the best I've got right now. :)

Edited by DaveWJr
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Are you sure it's chuffing? Chuffing does not sound like a rattle at all, it's unique. Can you roll your r's like you were saying arriba in Spanish? Chuffing sounds like you doing that without using your voice. It just sounds like air fluttering or flapping through something. The pressure multiplied by the velocity in a system is a constant when it's linear. You decrease the pressure, and the velocity goes up. This is what happens when you put your thumb on the end of a hosepipe: the pressure has dropped, but the velocity skyrocketed.

 

Chuffing is when the above falls apart and becomes nonlinear. This occurs when the area is too small for the velocity to increase and stay in shape. Think about merging 4 lanes of traffic into 1: you can't break the speed limit to keep the flow of traffic the same, so you get a traffic jam. Chuffing is that traffic jam inside a ported box. Putting tape over the port is just the sound of the tape causing a disturbance, not the port.

 

I would suspect a loose wire hitting a cabinet wall, hitting the port, or the leads on the driver slapping the cone. Again, chuffing is not a "hard" sound like a rattle. It's a fluttering, yet soft sound. Since you've only just now noticed it, I don't think it's chuffing. That would have been there since the first time you played it loudly. Can you confirm if it's soft sounding or hard sounding? That's the best I've got right now. :)

 

Thank you, but I'm 100% sure because it was established in this thread by others. They corrected me and showed me that it's just chuffing and it's normal for this subwoofer. Prior to making this post, I did not know about the word "chuffing". I'm serious (and I'm 36 years old for cryin' out loud). This is the first time that I have ever heard this sound before in my entire life, so I thought that something was rattling or vibrating inside, but it's just chuffing. It is indeed exactly as you described, but never hearing this sound before (in my entire life) and not knowing what chuffing is, I thought it was just a strange rattling sound instead. I didn't know about air turbulence in these things or anything like that.

 

As I stated, the only reason why I am just now noticing is, the movie that caused me to hear it is very new to my collection and it just so happens to be producing a huge amount of very deep low end in a sudden burst without any highs or mids to mask the chuffing (in the scene, it's a massive deep underwater explosion viewed from a distance above water). None of my other movies have such sound effects. So, this didn't just start happening out of nowhere. The problem is simply that I want more than this subwoofer can deliver cleanly without chuffing. For ~$150 though, I can't complain. I have learned that when I hear chuffing, I simply reduce the Subwoofer level a little bit. Fortunately, the point where the chuffing gets eliminated doesn't require me to turn it down to unpleasantly low levels.

 

So, the reason why you don't think it's chuffing is, you needed more information. However, this information has already been posted in this thread. ;) As a Klipsch Employee though, I imagine that your available forum time is limited and you're probably busy with other things, so it's all good.

 

So yeah, I have spent a ton of time and energy on figuring out that nothing is rattling, that this is just chuffing.

Edited by TwoCables
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Massive, deep underwater explosion viewed above water...may I surmise this is the beginning of the main depth charge scene in U-571? :)

 

hehe nah, I may have exaggerated the description a little in order to help describe the sound. It's a scene in Superman Returns.

Edited by TwoCables
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  • 11 months later...

Maybe this will help someone with the rattle issue:

 

READ - This is about the rattle in the subwoofer. 

 

I recently bought the Promedia 2.1's from Best Buy for $149.  Great price considering the Prime price on Amazon was up to $188.  

 

Well, I didn't get the 2 yr warranty but I thought maybe I'd return before before the 2 week window to add the warranty.  After noting the overheating issue on the back of the subwoofer almost immediately, I decided for $20 I'd go back to Best Buy and add the warranty.

 

My bad, I couldn't find my receipt after only about 10 days to verify my cash purchase.  To make matters worse, today, the day I planned on adding the warranty, the subwoofer developed a noticeable (very noticeable) rattle.  Forget about the warranty... I NOW WANTED TO RETURN THESE and instead get the Corsair SP2500 2.1 system at about $400 vs the $149 I paid for the Promedias.  Without the receipt, however, I've probably just thrown $150 out the window.

 

Just in case Best Buy wouldn't work with me on a return or exchange due to my lost receipt, I decided to look for a fix to the rattle in case I had to keep them.  Thanks to this thread I started trying to chase down the rattle and a possible remedy.  Based on the responses here I determined that my rattle which just appeared out of nowhere, wasn't from a blown subwoofer, but some kind of rattle between parts, probably due to inexpensive mass production assembly. 

 

FIXED ABOUT 95%!!!  I ran the text for the frequency where the rattle occurred at http://plasticity.szynalski.com/tone-generator.htm (thanks TwoCables for the link!)  Once I got the most noticeable rattle (between 50-90Hz) I let the tone play nonstop, then started trying to re-position the sub.  Well, certain positions made the rattle WAY worse while other positions almost did away with the rattle COMPLETELY!  

 

Turns out that facing the speaker grill down to the ground and adding a few rubber footpads under the grill-side to still allow for the speaker to move air, the rattle is now all but gone!  It's maybe 95-98% gone.  So, it's gone to the extent that it's now almost totally noticeable in the rare moments that it does still happen. 

 

Needless to say, the speakers by rotating the sub, sound great again.  The bass is strong and darn near 100% rattle-free.

 

Some Notes:  In the 10 days I've had the Promedias, I've never once turned the volume up past what would be about a 6 volume level (just past the half-way mark).  In addition, I've never turned the bass past the half-way mark, or in other words, I kept it at about a level 4.  This is important, because this illustrates that this is an issue of design and/or production quality - not an issue caused by product abuse.  So, Klipsch needs to remedy the build/production issues with this speaker system.  The speakers are a great value at $150 but the rattle mine developed with little use and no abuse was unacceptable at any price over $50, let alone $150 but most importantly for any product bearing the prestigious "Klipsch" name.

 

If Best Buy won't let me exchange these they're at least usable again - thankfully.  THANKS AGAIN FOR THE POSTS HERE THAT GOT ME ON THE RIGHT TRACK FAST.

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Maybe this will help someone with the rattle issue:

 

READ - This is about the rattle in the subwoofer. 

 

I recently bought the Promedia 2.1's from Best Buy for $149.  Great price considering the Prime price on Amazon was up to $188.  

 

Well, I didn't get the 2 yr warranty but I thought maybe I'd return before before the 2 week window to add the warranty.  After noting the overheating issue on the back of the subwoofer almost immediately, I decided for $20 I'd go back to Best Buy and add the warranty.

 

My bad, I couldn't find my receipt after only about 10 days to verify my cash purchase.  To make matters worse, today, the day I planned on adding the warranty, the subwoofer developed a noticeable (very noticeable) rattle.  Forget about the warranty... I NOW WANTED TO RETURN THESE and instead get the Corsair SP2500 2.1 system at about $400 vs the $149 I paid for the Promedias.  Without the receipt, however, I've probably just thrown $150 out the window.

 

Just in case Best Buy wouldn't work with me on a return or exchange due to my lost receipt, I decided to look for a fix to the rattle in case I had to keep them.  Thanks to this thread I started trying to chase down the rattle and a possible remedy.  Based on the responses here I determined that my rattle which just appeared out of nowhere, wasn't from a blown subwoofer, but some kind of rattle between parts, probably due to inexpensive mass production assembly. 

 

FIXED ABOUT 95%!!!  I ran the text for the frequency where the rattle occurred at http://plasticity.szynalski.com/tone-generator.htm (thanks TwoCables for the link!)  Once I got the most noticeable rattle (between 50-90Hz) I let the tone play nonstop, then started trying to re-position the sub.  Well, certain positions made the rattle WAY worse while other positions almost did away with the rattle COMPLETELY!  

 

Turns out that facing the speaker grill down to the ground and adding a few rubber footpads under the grill-side to still allow for the speaker to move air, the rattle is now all but gone!  It's maybe 95-98% gone.  So, it's gone to the extent that it's now almost totally noticeable in the rare moments that it does still happen. 

 

Needless to say, the speakers by rotating the sub, sound great again.  The bass is strong and darn near 100% rattle-free.

 

Some Notes:  In the 10 days I've had the Promedias, I've never once turned the volume up past what would be about a 6 volume level (just past the half-way mark).  In addition, I've never turned the bass past the half-way mark, or in other words, I kept it at about a level 4.  This is important, because this illustrates that this is an issue of design and/or production quality - not an issue caused by product abuse.  So, Klipsch needs to remedy the build/production issues with this speaker system.  The speakers are a great value at $150 but the rattle mine developed with little use and no abuse was unacceptable at any price over $50, let alone $150 but most importantly for any product bearing the prestigious "Klipsch" name.

 

If Best Buy won't let me exchange these they're at least usable again - thankfully.  THANKS AGAIN FOR THE POSTS HERE THAT GOT ME ON THE RIGHT TRACK FAST.

 

Interesting. If I did this, then I'd have to move my subwoofer closer to me because of the DIN cable (because of the design of my desk and where I must keep my subwoofer), but I still might try it just to see if it's worth it. I'll post again if I end up trying it to share my results.

 

The main reason why I'm replying though is to say that the 'Subwoofer' knob on the control pod is not for adjusting your Bass (it's not for adjusting the 'tone'). It's for adjusting the subwoofer's volume level independently of the main volume (it's like a mixer). So if you feel that you have too much bass, then you have to reduce it at the source. If that source is through Windows, then you can lower the bass directly in Windows. The default setting is 50%, but that's usually way too high for decent speaker systems that have a subwoofer. I keep my Bass level in Windows at around 15%, and I keep the 'Subwoofer' volume knob at the white mark for most things, but of course I adjust it from time to time depending on what I want at any given time.

 

The manual has this to say about it:

 

 

For CD or DVD output, the optimum position will be indicated by the mark at 10 o’clock on the sub level control. Optimum sub levels and user preference may vary from game to game. Usually a high bass level is preferred, especially at low listening levels. Remember to reset the control settings before playing CDs or films on DVD.

 

For me, the Subwoofer and Main Volume controls are like level controls on a mixer. The Suboofer level control contains all the low-end in the mix while the Main Volume adjusts everything together (so, it's an extremely simple mixer). In addition to that, I can further adjust the tone of that low-end by adjusting the Bass level and/or the low frequencies in a Graphic Equalizer. This is something the manual doesn't explain very well. It still leaves room for interpretation that the Subwoofer level will adjust the tone, giving you more or less bass, like an analog Bass Boost adjuster or something. So it's really just an independent volume knob for the subwoofer.

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