port noise? distortion?
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=105912
Printed Date: May 15, 2024 at 6:46 AM
Topic: port noise? distortion?
Posted By: wishuponansg
Subject: port noise? distortion?
Date Posted: July 03, 2008 at 10:19 PM
i got my new amp today, US amps xt2000D wired at 1 ohm, and installed it. it is powering 2 15" kicker cvr DVC 4ohm subwoofers. they are in a 2.9 cubic ft box (each chamber has 2.9 cubic feet), it is also ported. it seems im hearing some sort of noise come out of the port but, i cannot quite tell what it is. I'm not 100% sure what 'port nosie' actually sounds like, but it doesnt sound anything like distortion from the speaker (atleast i dont think it is). It just sounds like a little bit of wind blowing thru a hole or something (couldnt really think of anything else to describe taht sound, sorry). this sound comes directly out of the port, not the subs themselves. i also have them wired out of phase (which is going to be fixed tomorrow). any idea what this is?
Replies:
Posted By: i am an idiot
Date Posted: July 03, 2008 at 10:25 PM
Port noise. But you may be OK tomorrow, the speakers being wired in phase will dramatically increase their volume, thus possibly masking the port noise a bit.
Posted By: wishuponansg
Date Posted: July 03, 2008 at 10:46 PM
so wait, your saying that the port noise volume will increase? or my speaker volumer will increase?
Posted By: wishuponansg
Date Posted: July 03, 2008 at 10:52 PM
thanks for the incredibly speedy response, idiot. i feel so bad when i say that
Posted By: wishuponansg
Date Posted: July 03, 2008 at 11:00 PM
the gain settings and bass boost setting also seem to be limitless (as in i can turn it all the way, which i dont plan on doing very much) and i still dont get any distortion, could this be because of the out of phase issue? thanks.
Posted By: whiterob
Date Posted: July 04, 2008 at 12:07 AM
He means that when you have your subs in phase you may not be able to hear the port noise any longer.
How big is the port anyways? Port noise is caused by having a port with too small of a cross sectional area.
Having the subs in phase should also help figure out what to set the gain to. You should be able to hear the distortion better. If you still can't hear it set the gain with a DMM.
Posted By: wishuponansg
Date Posted: July 04, 2008 at 12:44 AM
ok, thanks for the clarification. im not exactly sure how big the port is (its just a shotty prefab box), ill meaure it tomorrow when i fix the out of phase sub tomorrow.
Posted By: DYohn
Date Posted: July 04, 2008 at 11:18 AM
wishuponansg wrote:
i got my new amp today, US amps xt2000D wired at 1 ohm, and installed it. it is powering 2 15" kicker cvr DVC 4ohm subwoofers. they are in a 2.9 cubic ft box (each chamber has 2.9 cubic feet), it is also ported. it seems im hearing some sort of noise come out of the port but, i cannot quite tell what it is. I'm not 100% sure what 'port nosie' actually sounds like, but it doesnt sound anything like distortion from the speaker (atleast i dont think it is). It just sounds like a little bit of wind blowing thru a hole or something (couldnt really think of anything else to describe taht sound, sorry). this sound comes directly out of the port, not the subs themselves. i also have them wired out of phase (which is going to be fixed tomorrow). any idea what this is?
Yes, that seems to be port noise you're describing. Fix your phase issue, set your gain properly, and let us know if you still have issues. ------------- Support the12volt.com
Posted By: i am an idiot
Date Posted: July 04, 2008 at 5:48 PM
wishuponansg wrote:
the gain settings and bass boost setting also seem to be limitless (as in i can turn it all the way, which i dont plan on doing very much) and i still dont get any distortion, could this be because of the out of phase issue? thanks.
The gain and bass boost were probably only causing more movement from your woofers. No change in the sound at all. Your woofers were out of phase, one woofer is canceling the other out. Turn gain up and woofer A moves more, but so does woofer B, but in the opposite direction, thus canceling out the extra movement of woofer A. Let us know if you can hear the port noise after proper phasing.
Posted By: wishuponansg
Date Posted: July 04, 2008 at 11:41 PM
well i tried switching the pos. and neg. wires on one of the speakers today and had worse results. the subs seemed to be still out of phase, and were much, much quieter, and distorted much quicker (when setting the gains and bast boost). port noise was still there. the port noise is only noticeable when you put your ear practicaly in the port so im not to worried about it. are the subs going to be damaged if i cant fix the phasing problems?
Posted By: stevdart
Date Posted: July 05, 2008 at 9:01 AM
wishuponansg wrote:
(its just a shotty prefab box)
You have a prefab box that is 6 cu ft in size? Any way you can link to it? Starting back at square one and building a custom enclosure is most important if you are to lick these nagging problems. ------------- 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: DYohn
Date Posted: July 05, 2008 at 10:02 AM
Since you have not corrected whatever phase issue you have, open your enclosure and ensure your wiring looks like this (for a 1-ohm load with 2 DVC 4-ohm woofers): 
------------- Support the12volt.com
Posted By: wishuponansg
Date Posted: July 05, 2008 at 10:47 AM
stevdart wrote:
wishuponansg wrote:
(its just a shotty prefab box)
You have a prefab box that is 6 cu ft in size? Any way you can link to it? Starting back at square one and building a custom enclosure is most important if you are to lick these nagging problems.
i would link to it, but i bought it off of ebay. i know, its pretty big for a prefab.
Posted By: wishuponansg
Date Posted: July 05, 2008 at 10:47 AM
DYohn] wrote:
p>Since you have not corrected whatever phase issue you have, open your enclosure and ensure your wiring looks like this (for a 1-ohm load with 2 DVC 4-ohm woofers):
i know one of them is wired in 1 ohm, i guess i was pretty stupid when i just assumed that the other one was also.
Posted By: wishuponansg
Date Posted: July 05, 2008 at 10:52 AM
one more thing, my amp has 2 sets of positive and negative terminals (for different speakers, it is a monoblock amp). was i supposed to fit both of wires into one set? i checked out the manual and it looks like what i have.
Posted By: DYohn
Date Posted: July 05, 2008 at 12:50 PM
wishuponansg wrote:
one more thing, my amp has 2 sets of positive and negative terminals (for different speakers, it is a monoblock amp). was i supposed to fit both of wires into one set? i checked out the manual and it looks like what i have.
Sine it is a mono amp, you may use one set or both it does not matter. Have you checked the wiring on both subwoofers and ensured it is like the image I posted? ------------- Support the12volt.com
Posted By: wishuponansg
Date Posted: July 05, 2008 at 4:49 PM
DYohn] wrote:
p>wishuponansg wrote:
one more thing, my amp has 2 sets of positive and negative terminals (for different speakers, it is a monoblock amp). was i supposed to fit both of wires into one set? i checked out the manual and it looks like what i have.
Sine it is a mono amp, you may use one set or both it does not matter. Have you checked the wiring on both subwoofers and ensured it is like the image I posted?
yes i did. both are wired correctly to make it a 1 ohm load. im stumped. i guess ill try switching the other speaker's pos and neg wires around? i only switched one of the speakers wires the first time. any one have any ideas?
Posted By: DYohn
Date Posted: July 05, 2008 at 5:09 PM
As long as you have all four positives wired together to one of your positive terminals, and all four negatives wired together to the negative terminal, then you are correct and you do not have a polarity issue (unless one of the voice coils is mis-marked.) Set your gain properly and see what happens. Please post what you think is wrong after you set your gain. ------------- Support the12volt.com
Posted By: wishuponansg
Date Posted: July 05, 2008 at 6:12 PM
well, i've already set the gain, and it is plenty loud. it sounds as loud as it should without any distortion. its just that the speakers move opposite of each other. other than that it's fine. you also kind of lost me when you said 4 of each positive and negative wire. i have 2 positive (1 from each speaker) and 2 negative (one from each speaker) wires, and each of them are going into their own terminal. so, essentially i have 4 terminals, with 1 wire going into each one. i really appreciate that help and patience.
Posted By: DYohn
Date Posted: July 05, 2008 at 6:56 PM
wishuponansg wrote:
well, i've already set the gain, and it is plenty loud. it sounds as loud as it should without any distortion. its just that the speakers move opposite of each other. other than that it's fine. you also kind of lost me when you said 4 of each positive and negative wire. i have 2 positive (1 from each speaker) and 2 negative (one from each speaker) wires, and each of them are going into their own terminal. so, essentially i have 4 terminals, with 1 wire going into each one. i really appreciate that help and patience.
I thought you said your speakers were DVC. What is the make and model number? ------------- Support the12volt.com
Posted By: wishuponansg
Date Posted: July 05, 2008 at 7:04 PM
they're kicker compvr cvr15
Posted By: i am an idiot
Date Posted: July 05, 2008 at 7:22 PM
wishuponansg wrote:
its just that the speakers move opposite of each other.
With music as a source, you can not see that a speaker is out of phase.
Posted By: wishuponansg
Date Posted: July 05, 2008 at 8:20 PM
i am an idiot wrote:
wishuponansg wrote:
its just that the speakers move opposite of each other.
With music as a source, you can not see that a speaker is out of phase.
wow... i feel dumb as hell. what are the woofers moving at opposite times a sign of?
Posted By: DYohn
Date Posted: July 05, 2008 at 8:32 PM
Do you have a 9-volt battery? Disconnect the speakers from your amp and connect the speaker leads to a 9 volt battery. If they both move the same direction they are not out of phase. ------------- Support the12volt.com
Posted By: i am an idiot
Date Posted: July 05, 2008 at 8:37 PM
I really do not know the answer to that question. A 45 Hz bass note moves the speaker in and out at the rate of 45 times a second. I am sure you have one woofer that on an extended bass note appears to be moving in, and the other appears to be moving outward. I have seen this many times, I mean many. Never had a need to figure out what caused this phenomenon.
Posted By: DYohn
Date Posted: July 05, 2008 at 8:42 PM
i am an idiot wrote:
I really do not know the answer to that question. A 45 Hz bass note moves the speaker in and out at the rate of 45 times a second. I am sure you have one woofer that on an extended bass note appears to be moving in, and the other appears to be moving outward. I have seen this many times, I mean many. Never had a need to figure out what caused this phenomenon.
Timing issues due to differences in DCR and inductance, as well as series resistance from speaker wires, can cause this. ------------- Support the12volt.com
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