Not reaching full Xmax. Should I be?

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=81637
Printed Date: July 13, 2025 at 2:34 AM

Topic: Not reaching full Xmax. Should I be?

Posted By: trustyrusty
Subject: Not reaching full Xmax. Should I be?
Date Posted: August 15, 2006 at 1:02 AM

I recently finished totally putting together my system in which I am pretty happy. I have a JBL BP1200.1 amp, 2 Cerwin Vega VMax's (300rms ones), and then two acoustic elegance 15" passive radiators all in a 5.8cu. foot box. i have PG 4gauge amp kit and ground going to it which is all nice and well. I just regrounded it and those all check out. I then upgraded my subwoofer wiring to 12gauge (from previous monster 16gauge), so thats taken care of. After that was all set and done, I was playing some late night tip on it, and I realized that my subs don't look like they are really moving all that much. The Vmax's have a 20.3mm Xmax and I didn't think that was what i was getting. So after looking at my graph in WinISD, i noticed that my cone's excursion peak is only about 14.4mm at around 26hz. My box with the PR's in them is tuned to 18.04(if that matters at all). I increased the power to 3200watts in winISD and then it finally was hitting full Xmax around 22hz on the graph if that means anything. This may seem like a stupid question, but if the subs are rated at 300rms, and i'm giving them 500 to 600 a piece, how come I can't even hit full Xmax no matter the frequency?

Replies:

Posted By: KarTuneMan
Date Posted: August 15, 2006 at 1:28 AM

How do you know you are NOT reaching "full xmax" and why is that important?

Posted By: DYohn
Date Posted: August 15, 2006 at 7:41 AM

You can't hit full Xmax because the enclosure is doing its job properly. Unless you are looking for a SPL competition single burp, you do not want your speakers operating at Xmax unless you want to fry them rather quickly. Besides, WinISD is a tool for designing systems, it cannot accurately predict what will happen in the real world. Like Kartune asked, how do you know you are not reaching Xmax? Are you measuring cone excursion with a laser?

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Posted By: trustyrusty
Date Posted: August 15, 2006 at 11:03 AM

Well I wasn't sure if I should be hitting full Xmax or not, but I guess if I'm still getting good sound, it's better not to considering I am running them over there RMS rating and if the thermal doesn't get it to fry, then Xmax is usually the next thing that will kill a subwoofer.

I am pretty sure I am not hitting Xmax because i played an 15hz test tone in which my VMax's definetely hit full Xmax i'm sure, or at least a lot more then before.

It's not so much that I want them to, I am very happy with them now and I am even more happier with a non-blown sub that doesn't hit XMax then a blown sub that did for like 10 seconds, posted_image

. Looks like it was just a good job with my enclosure and I guess I don't need to worry about it then.
Thanks!

Posted By: cloak559
Date Posted: August 15, 2006 at 1:25 PM

Do you actually know what xMax is?...It sounds to me like you need a refresher course on subwoofer anatomy and terminology....

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'89 Mercedes-Benz 300E
Pioneer DEH-5900UB
(2)RE Audio SX 10"s
(1)US Amps MD3D
3ft^3 @ 37Hz

Blowing up in a car accident doesnt worry me, as long as I'm putting out some major dB's when I die...

Posted By: stevdart
Date Posted: August 15, 2006 at 3:41 PM

It seems like there's been a recent movement regarding the importance of Xmax. Everyone should know what it is so they don't reach it...but the common thought now seems to be that it must be reached.

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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: aznboi3644
Date Posted: August 15, 2006 at 3:55 PM

Well...either that or it just looks cool to see how far a sub can move...I always enjoy watching.

If you wanna see your subs at full excursion...lay it on the ground in free air and plug em into the wall outlet.

Posted By: trustyrusty
Date Posted: August 15, 2006 at 11:41 PM

Yea, I'm well aware of Xmax...but i just thought that according to the graph its 6mm away from it. I'm not trying to push for a full Xmax SPL box, but i didn't know if 6mm was enough for it not being to the max to be concerned. My questions have been answered fully now. as for wall socket's...i've seen enough of that, haha

I probably should have rephrased my question into being...i'm 6mm off peak one way Xmax at full volume before clipping, is that to much?

Posted By: KarTuneMan
Date Posted: August 16, 2006 at 1:04 AM

trustyrusty wrote:

Well I wasn't sure if I should be hitting full Xmax or not, but I guess if I'm still getting good sound, it's better not to considering I am running them over there RMS rating and if the thermal doesn't get it to fry, then Xmax is usually the next thing that will kill a subwoofer.

I am pretty sure I am not hitting Xmax because i played an 15hz test tone in which my VMax's definetely hit full Xmax i'm sure, or at least a lot more then before.

It's not so much that I want them to, I am very happy with them now and I am even more happier with a non-blown sub that doesn't hit XMax then a blown sub that did for like 10 seconds, . Looks like it was just a good job with my enclosure and I guess I don't need to worry about it then.
Thanks!

use commen sence man....you won't here a 15 cycle note in normal listening.... X-max means nothing, unless your over powering your sub, or flooding it with "way too low" information...

Posted By: kfr01
Date Posted: August 16, 2006 at 11:37 PM

You don't want to reach xmax. If your subwoofer isn't moving much at your listening volume... GOOD!

Also. You "HEAR" with your ears. I am "HERE" sitting at my computer.

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