sub experts... whats wrong with this sub?

[tcguy85 10+ year member]

i dropped a midbass once and it sounded like what yours is sounding like, the magnet was a little off set from the basket, and you could hear the coil kinda rubbing a little bit when you would push in it just right, banged on it a little bit and got it lined up again and she worked great, good old radioshack speakers, and sorry to thread jack but whats an rta and how do you set phase? and whats t/a? i just wanna know the phase thing cause ive got two L7s and they dont move in sync with eachother and it bothers me, good luck with the sub though

rta stands for real time analysis. it's a system that measure frequency response.

usually you set your phase by ear but the rta will make it a whole lot easier especially when you have a dial for your phase adjustment, not just a switch(180 or 0).

t/a is time alignment. you set the distance between you and all the individual speakers. t/a also affects phasing to some degree.

BTW this sub is for my HT(home theater).

 

[muskyhunter567 10+ year member]

riiiiight, im new and abbriveations throw me off, so how do you measure with an rta? you would use it for HT so it matches up with your normal speakers so it doesnt cancel out your bass correct?

 

[tc3k101 5,000+ posts]

dope sub ive wanted one for some time now. tried getting one local dude never responded.

sucks its fvcked up. let me know how u like it

 

[tcguy85 10+ year member]

riiiiight, im new and abbriveations throw me off, so how do you measure with an rta? you would use it for HT so it matches up with your normal speakers so it doesnt cancel out your bass correct?

you can use the rta anywhere ya want. i use it in both my car and my HT.

my rta consists of the following:

http://www.samedaymusic.com/product--MXLUSBMICMATE

http://www.samedaymusic.com/product--BEHECM8000

http://www.trueaudio.com

and a usb cable to connect the mic-mate to my laptop.

you simply play pink noise though the system and tune it.

 

[tcguy85 10+ year member]

dope sub ive wanted one for some time now. tried getting one local dude never responded.
sucks its fvcked up. let me know how u like it

it should be a sick *** sub.

this is the response at my listening position. it's in a 3.32 cubic foot sealed box.

the low end extension is unreal. room gain FTW!

it sounds great other than the scratching clicking sound of the coil rubbing on the motor. //content.invisioncic.com/y282845/emoticons/crap.gif.7f4dd41e3e9b23fbd170a1ee6f65cecc.gif

 

[Immacomputer 10+ year member]

It has nothing to do with Xmax and bottoming out.
It has to do with non linear movement.

I have seen it many times before when frequencies that were too low were played, especially with subs with no acoustical suspension i.e. no enclosure. Or a ported enclosure where the F3 was above the frequency being played.

Can I ask what frequency was being played?

I think you misunderstand what is meant by "linear" movement of a speaker. This doesn't mean the speaker moves in a perfectly straight line up and down. The linear region means that the magnetic field acting on the coil is constant within a certain stroke distance. Outside of the distance, the coil acts nonlinearly because the motor force or suspension parameters begin to shift and these parameters throw off other parameters of the driver and the output becomes distorted.

The problems you're describing are from pushing the mechanical limits of a sub, which can happen playing frequencies too far below tuning or in an IB situation but the damage doesn't come from the frequency but from the over excursion. He's not over driving the suspension so the sub is still operating within the linear region, both electrically and mechanically.

It's too bad it's like that.

 

[audioholic 5,000+ posts]

Its a mis-aligned coil probably. There's no way its from too low of a frequency.

 

[audioholic 5,000+ posts]

I think you misunderstand what is meant by "linear" movement of a speaker. This doesn't mean the speaker moves in a perfectly straight line up and down. The linear region means that the magnetic field acting on the coil is constant within a certain stroke distance. Outside of the distance, the coil acts nonlinearly because the motor force or suspension parameters begin to shift and these parameters throw off other parameters of the driver and the output becomes distorted.
The problems you're describing are from pushing the mechanical limits of a sub, which can happen playing frequencies too far below tuning or in an IB situation but the damage doesn't come from the frequency but from the over excursion. He's not over driving the suspension so the sub is still operating within the linear region, both electrically and mechanically.

It's too bad it's like that.

I have seen subs linear excursion affected by mounting the subs non-symmetrically in realtion to the interior walls of the enclosure. This can place a non-uniform load around the circumference of the cone which could lead to non-linear excursion under extreme conditions. But I agree in this case that's definitely not the case.

 

[tcguy85 10+ year member]

they sent me out another. i just hope it gets here quicker than the 1st, which took 9 days.

 

[ramdaspadhye 10+ year member]

Are you planning on running it sealed only? I know these Shivas and Tempests like large enclosures, but had you thought about trying it in a 2-4 cu ft ported enclosure to see what the freq response is?

 

[Gilliz 10+ year member]

Yea, I call assembly error on this one. GL with new one.....5....6....7...8...9...days from now .

 

[tcguy85 10+ year member]

Are you planning on running it sealed only? I know these Shivas and Tempests like large enclosures, but had you thought about trying it in a 2-4 cu ft ported enclosure to see what the freq response is?

yup sealed only. if you look at the in-room response graph i posted you'd see the VERY flat and very extended frequency response.

it's perfectly flat (within 1 db) from 16hz up to 60hz. it's only down 2db at 12hz. so the F3 in room is at like 10-11hz. thats plenty low.