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Discussion Starter #1 (Edited)
How much does suspension noise vary between drivers?

I have an SDX15. At about 15mm it begins to make gurgling/motorboating noises (tested in free air at 20Hz). These noises steadily become worse until by full travel it's making quite a bit of racket.

Just curious if the other popular drivers (Tempest X2, Av15, Mach IXL 15 etc, etc) have similar amounts of suspension noise or are some noticeably better than the others?

EDIT: FWIW, I hear the "knocking" that Ricci mentions on both my drivers. So it appears to be normal for the SDX.
 

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ive always had a bit of noise running drivers free air, motor noise as well as suspension i would assume. it is masked when in an enclosure. only so much though, if it is bad there may be a problem. I broke in a pair of 15's once free air and 1 driver was loud the other "normal" upon closer inspection, 1 driver had a small dent on the mounting flange..probably shifted things enough to misalign it
 

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Discussion Starter #3
Ya, I meant all the various extraneous noises the driver makes.

Mainly I was curious if they varied that much. I'd definitely buy one that was the same in other respects but quieter. Depending on frequency it's audible if one knows what to listen for (in that sense, ignorance is bliss).
 

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Yes they do vary even between subs of the same kind. Seems like the big excursion subs have a few main issues which are spider slap, vc rock and surround deformation. There's also a difference between the sounds. There's a high excursion sort of (whoosh) sound that is the suspension stretching out, the spiders , distortion, air flow through the motor etc. I'd consider this normal. Then there is a mechanical type sound like a tapping or knocking that is not due to the sub bottoming out. My SDX's have this pronblem at around 20mm and to me it sounds like either coil rock, or spider slap, can't tell which. A lot of people have mentioned this so it seems common. My LMS is basically free from any bad noises until about 30mm or more until you start to hear the whoosh noise and even then there isn't any of the obvious mechanical stuff like on the SDX's. My XXX's are hit and miss 3 of them are free from anything other than normal suspension noise issues up until 40mm or more and the other 2 start exhibiting a tapping sound around 25mm, but they function fine well past that point. I was going to recone those 2, but you really don't notice it in use. It think it's coil rock, because they are very deep motors. My 2 12" Eminence drivers from Danley Sound Labs were very clean up until about 20mm and only made heavy suspension overload sounds at around 25mm (rated at 15mm versus 30mm for the SDX if that shows you anything).

It's all over the map.
 

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I guess I'll make this my very first post in this forum.

I have the IXL 18.2.2 in an 11Hz LLT - it does the whooshing thing Ricci mentioned at full throw, but I've never heard it sound like a motorboat. Suspension noise does vary though, as mentioned.

It's actually kind of cool when mine whooshes... that's when I know it's singing for its supper :D
 

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I guess I'll make this my very first post in this forum.

I have the IXL 18.2.2 in an 11Hz LLT - it does the whooshing thing Ricci mentioned at full throw, but I've never heard it sound like a motorboat. Suspension noise does vary though, as mentioned.

It's actually kind of cool when mine whooshes... that's when I know it's singing for its supper :D
free air or in box? If in box, sound from the driver port or both?
 

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In box, coming from the driver. You have to pay attention to hear it, and I haven't heard it since I made the box go stand in the corner with the driver firing straight at the corner. Box is 25.5 x 25.5 x 49."

The port is 5.9" x 40" facing downwards... I have to really crank it at 11Hz to hear anything from there.
 

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My Maelstrom 21" makes some funny noises when it's pushed. The 3Hz tones around 30-37seconds in this video you can hear it wump, wump, wump. The rattling sounds you hear are things in the room. I'm still trying to track down everything that rattles and try to make it all more secure. I believe my driver noise to be suspension. I've never heard it since this video, because I don't often torture it with 3Hz tones.

 

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I want one of those. Especially since the IXL doesn't quite do it for me, I need a shallower box to go behind a projector screen, and I have some amp power not being taken advantage of.
 

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That sounds like the suspension hitting the stops (reaching Xmech.) Is that enclosure vented?
 

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That's a possibility... I was just reading through the build thread on that beast. 16 cubes sealed - seems a bit on the large side for that bad boy.

I'm still torn on whether I'd even try an LLT with that monster, or just go sealed myself with a bit smaller of a box. I'm only limited by depth and height... it's a straight shot down the stairs and into the home theater here. Length likely won't be an issue.

Glad to see an EP-2500 is able to push it. I have an RMX-1850HD I plan to saddle it with :)
 

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My Maelstrom 21" makes some funny noises when it's pushed. The 3Hz tones around 30-37seconds
Stop doing that! You will seriously destroy your driver trying that stuff.

pushing a driver hard below it's Fs isn't suggested. Regardless the driver/design. I suggest you play it safe.

I'm really concerned about that beautiful sub. I will call sub protective services if you continue. :hissyfit:
 

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Nothing wrong with temporarily testing and finding your limits so long as youre careful. He carefully planned ahead with the intention of making 1 vid, and he never actually bottomed it and doubt any damage was caused. I don't think he will push it anywhere near that again either.

What does driver Fs have to do with how hard you can push it below its Fs?
 

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The Fs is as low as most drivers can safely produce useful undistorted sound. Below that distortion rises very rapidly.
 

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The Fs is as low as most drivers can safely produce useful undistorted sound. Below that distortion rises very rapidly.
let me see some links please


BTW Kevin himself brings the drivers to stress in his demo vids showing where the limits are. why? cuz hes not ripping spyders tearing tinsel leads and hard bottoming coils. or leaving it like that for long periods of time.
 

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Discussion Starter #18
The Fs is as low as most drivers can safely produce useful undistorted sound. Below that distortion rises very rapidly.
The increase in distortion isn't due to safety issues. It's mainly because the fundamental begins rolling off below resonance but the excursion related distortion products don't.
 

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That sounds like the suspension hitting the stops (reaching Xmech.) Is that enclosure vented?
I'm not sure about that. It doesn't look close to 40mm at all...

Here's a video of my sub playing Bass I Love You. Watch it on the 8hz tones...:


Maybe Raven's noise is a slight amp clip, and the red clip lights just aren't picking up on it?
 
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