Knocking sound

[mustbenu 0]

hi

Edited April 3, 2006 by mustbenu

[Eldorado 0]

bottoming out

turn the volume down

[///M5 2,833]

the real answer is in your question

[flakko 1]

yes wat kinda box you have? i thought mags could take more

[Tirefryr 1,742]

Power handling is enclosure dependant. And even that is only if the actual power is power, if you know what I mean.

[Electrodynamic 2]

Bottoming out or clipping, one of the two.

[mustbenu 0]

it cant be clipping because i set it with a DMM with a -6db test tone at 50hz

and it was just under the max volume... its in a 2.6ft sealed box.

[Tirefryr 1,742]

That doesn't mean it's not clipping. If you're feeding s clipped signal, you're already screwed. Fact of the matter is, 90% of todays recordings are crap, and they get worse as you shuffle them around from your computer to CD, etc.

I think it's time to tunr it down a little. Granted, the driver may be able to handle more power, but clearly you don't need it. You're obviously reaching some mechanical limits already and there's no need to dump anymore into it.

[Electrodynamic 2]

^What Tirefryr said. My Alpine 9813 would clip like it was its job at/near 3/4 max volume where as my 8v Eclipse has yet to clip even at full tilt.

[NDMstang65 403]

coil wont reach the backplate

will it?!

[mustbenu 0]

so the DMM method is pointless then?

[Electrodynamic 2]

Well you've got to think about it - your amplifier will only send back back out what it is given. If you feed it a clipped signal, it will send out a clipped signal. My Alpine 9813 started clipping at/near 31 (I believe its max was 40) where as my Eclipse has yet to clip even at full tilt. To be super sure you can grab an o-scope to see where your HU starts clipping at.

[mustbenu 0]

i have a jvc touch screen headunit, is there any type of head unit that doesnt clip as earlier or is there a way to know which headunits clip at what points. at the volume it was getting a knocking sound my front speakers were sounding crystal clear

[jntar 15]

i have a jvc touch screen headunit, is there any type of head unit that doesnt clip as earlier or is there a way to know which headunits clip at what points. at the volume it was getting a knocking sound my front speakers were sounding crystal clear

<{POST_SNAPBACK}>

You can buy an ocilliscope that will tell you when the clip. Try setting all the gains with the volume on your HU lower. If it still make the sound you are over driving the subwoofer.

[Tirefryr 1,742]

If you really wanna get into it, chances are the material you are playing has clipping as well.

[Renegadesrun 0]

Bottoming out... ie ... hitting the coil hangers.

Box tuned to closely to the FS of the subs OR amp adjustment, or too much power. Considering impedence rise robs almost everyone of actual output of the amp i choose one of the latter 2.

[Trevor Eaton 0]

youd want to tune at 0db recording too btw...

[sundownz 197]

i have a jvc touch screen headunit, is there any type of head unit that doesnt clip as earlier or is there a way to know which headunits clip at what points. at the volume it was getting a knocking sound my front speakers were sounding crystal clear

Sounds like your sub amplifier gain is too high or your mid/high amplifier gain is too low. I don't know of many front stage setups outside of the high end realm that will keep up with a Mag if they are level matched.

Chances are you are simply pushing the sub too hard mechanically. You set your gain at 50 Hz, if you drop down to 25 Hz and you require 4x the excursion for the same SPL output.

The song you are listening too probably has some very low information that pushes the sub to a point where you get a slapping sound... which is probably the tinsel leads as the Mags really won't bottom out unless you tear the spider. It can *possibly* have a lead slapping sound in the right set of circumstances; eg: mechanical overdrive, as the leads will not slap in normal operation.

Thermally you are okay with 1000 watts but you can exceed the linear x-max capabilities of the subwoofer at a low enough frequency. Does your amplifier have a subsonic filter? If so, have you tried playing with this a bit to see if perhaps it helps? Chances are the notes that are causing the slapping sound are nearly inaudible anyway, so filtering them out won't effect your listening noticeably other than reliving the mechanical slap.

Edited March 31, 2006 by sundownz