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overpowering subs?

Printed From: the12volt.com
Forum Name: Car Audio
Forum Discription: Car Stereos, Amplifiers, Crossovers, Processors, Speakers, Subwoofers, etc.
URL: https://www.the12volt.com/installbay/forum_posts.asp?tid=103802
Printed Date: March 29, 2024 at 6:49 AM


Topic: overpowering subs?

Posted By: michael.laroya
Subject: overpowering subs?
Date Posted: April 07, 2008 at 5:25 PM

I have 2 cerwin vega 12" subwoofers (400rms ea. and 800watts max ea) I wanna put a fosgate T10001BD amp (1000wattsx1 @1ohm). Do you think it's to much for the subs?

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bighead



Replies:

Posted By: stevdart
Date Posted: April 07, 2008 at 7:06 PM

No, but I'd still rather know the pertinent info on your setup, which includes: 

  • What is the combined impedance of the subs going to be?
  • Are the subs going into a vented, sealed or *choke * bandpass?

If you're wiring to 1 ohm and using a vented box, when setting the gain you might have to be listening (and watching) for evidence of over-excursion or bottoming out...instead of listening only for the clipping sound.



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Build the box so that it performs well in the worst case scenario and, in return, it will reward you at all times.




Posted By: sedate
Date Posted: April 07, 2008 at 8:14 PM
"headroom is your friend"

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"I'm finished!" - Daniel Plainview




Posted By: michael.laroya
Date Posted: April 08, 2008 at 10:44 AM
I am wiring them at 1 ohm and using a vented box, and how can you tell if there is over-excursion or bottoming out or clipping sound.


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bighead




Posted By: Blowntweeters
Date Posted: April 08, 2008 at 11:20 AM
if i remember correctly bottoming is a snaping sound very loud and noticable.you could easily execeed the thermal limits of those subs . if you could give the model # of the subs. just use good judgement. if they sound like there gonna break back off the volume and or gain.do you plan on upgrading your subs?

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1974 ford pinto 4 15" punch Z power punch bd 1001 pioneer DEH-6700




Posted By: michael.laroya
Date Posted: April 08, 2008 at 11:44 AM
They are Vega 124D (DVC). I am very happy with these subs but have been contemplating on upgrading. Maybe JL W6/W7 or maybe a stroker.

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bighead




Posted By: Blowntweeters
Date Posted: April 08, 2008 at 12:03 PM
do you already have that amp ?  do you like RF products. JL W6 and W7 are SQL type subs . there well rounded but not the best of both worlds.if you like RF products . i would buy that amp . take it easy on those. and upgrade later

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1974 ford pinto 4 15" punch Z power punch bd 1001 pioneer DEH-6700




Posted By: michael.laroya
Date Posted: April 08, 2008 at 1:30 PM

This would be the first RF product I would own but I don't have it yet. I just got a new (used) car and just wanted to keep some of my old equipment. Here is my planned set up

Alpine IVA-W205 (head unit)

4 Pioneer 6.5 4 way speakers TS-A1682R (280 watts max each)

2 Alpine 3/8 sps 1005 tweeters (120 watts each max)

T10001BD amp (1000wattsx1 @1ohm)

2 12" Cerwin Vega 124D (DVC) (400 watts RMS each)

Clarion MCD360 3 way x-over

Capasitor (?) any sugestions

Amp for mids (?) any sugestions



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bighead




Posted By: Blowntweeters
Date Posted: April 08, 2008 at 3:19 PM

are u on a buget ? https://www.ikesound.com/product-product_id/4391 this heres a link for a good amp for your mids and highs. https://www.ikesound.com/product-product_id/3384 and i would suggest this amp over the rockford.



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1974 ford pinto 4 15" punch Z power punch bd 1001 pioneer DEH-6700




Posted By: michael.laroya
Date Posted: April 08, 2008 at 3:36 PM
The link for the mid amp won't show up. You really think that amp is better than the RF?

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bighead




Posted By: aznboi3644
Date Posted: April 08, 2008 at 4:11 PM
bottoming out is a loud clanky mechanical noise.

What happens is the former slams against the backplate. Either that or the spider/former joint hits the bottom of the basket if the latter doesn't come first




Posted By: stevdart
Date Posted: April 08, 2008 at 8:32 PM

...And over-excursion occurs before it gets to the point of bottoming out.  There is a defined amount of play (excursion) which you will find reference of in the parameter notes.  Say, for example, it has Xmax listed as 17 mm.  Look at that distance on a metric ruler and you will see what it's playable limit of one-way excursion is.  With your hand, push the cone from its resting position.  It will be within the boundaries of the specified Xmax if you push it back to any point up to 17 mm.  The cone can also extend forward from resting position that same length, safely.

While playing, you will see the cone move forward and backward equally (or very much so).  The excursion you see will appear as Xmax * 2.  The sub with a specified Xmax of 17 mm will appear to move within a range of 34 mm (17 mm * 2) and still remain within its safe excursion range.  That translates to a total range of 1 1/3 inches and is the distance you will judge when looking for over-excursion.  Figure out the total excursion range for your sub based on its Xmax.

But it will go farther...but then will be out of boundaries and precision will be lost.  This longer area of one-way excursion is noted as Xlim, or the limit of excursion.  It allows the sub to stay in one piece when encountering the occasional thump that might occur in a soundtrack.  It is also there to allow for some amount of the excursion problems that come when the sub is playing tones below the box tuning frequency and those lower freqs aren't being adequately filtered.  You really want your sub to stay out of that area, though.

So when I said you should be watching for the overexcursion, that means you should make a note of how far back or forward that sub can healthily go and watch for out-of-the-ordinary wobbling or fluttering.  This will occur in a vented box if all the setup conditions aren't being met properly.  Those conditions include (possible) use of a subsonic filter and extra care in preventing an overpowering situation (which you can use the amp's gain for).

Take extra care in the setup by playing recorded tones at lower freqs to see if you have filters set correctly.  If the sub has to play those tones that are well below the box tuning frequency, it will lose control of its excursion because the box has lost control over the damping of the sub.  This is where you notice suddenly greater amounts of excursion and out of control movement that I call "flutter".  At the same time, you don't want to set a subsonic filter higher than it needs to be set because you could lose some of the low freq range your vented box may be designed to enable.



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Build the box so that it performs well in the worst case scenario and, in return, it will reward you at all times.





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