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Sub Distortion question

5K views 24 replies 8 participants last post by  jacobpritchett 
#1 ·
Hey guys,

I recently installed a 10" P3 Rockford sub, powered by a RF 300-1 Punch amp. (acutally puts out 420 watts RMS, despite being rated at 300). I installed it in a sealed enclosure, put silicone on all the joints, used wood glue, etc. to make sure it was airtight...however when I listen to music with heavy bass and low frequencies I get a fair amount of distortion ( kinda like a vibration/flapping noise) Now I know 10" subs and sealed enclosures arent ideal for synthetic bass like in rap/hip hop, but I was just surprised at the distortion. Is it possible the box isn't airtight like I think it is? Most all other music sounds perfect, but I was a little dissapointed when listening to music with the heavier bass.

(I attached some pics of the setup)
 

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#2 ·
Is this the shallow mount p3? My brother has a 12" P3 and it does the same thing. His is in a silverado though. Maybe its just Rockford subs are having a problem with heavy bass oriented music? Maybe someone with more knowledge than myself can answer your question for sure.
 
#3 ·
Check gain and equalizer settings first, then move on to the box. How was the gain set and is there any boost of any kind involved? How do you know for sure what the amp puts out? Did you by any chance use a voltmeter to set the gain, and if so did you use a calculation for the 420 watts that you believe the sub puts out or for what it's actually rated at by the manufacturer? What type of equipment do you have in the rest of your system? Is only the sub amplified or are the front speakers too? Have you high-passed the front speakers properly? Where is the sub crossed over in relation to the rest of the speakers?

I am not a box expert but I can tell you if your settings may or may not be an issue. May also get some useful info in the audio section.
 
#4 ·
Lower end Rockford products dont do well with rap-type bass. You could try turning any and all EQ settings off (including bass boost on the amp). You could also increase your lower bass response by porting the box to Rockfords specs.

Whiskey Lover - Most Rockford and Kicker amps come with a "birthsheet" that shows what the amp benches at despite the rating. However, I do think a 420w bench is a bit high for a 300w amp.
 
#5 ·
Is this the shallow mount p3? My brother has a 12" P3 and it does the same thing. His is in a silverado though. Maybe its just Rockford subs are having a problem with heavy bass oriented music? Maybe someone with more knowledge than myself can answer your question for sure.
Its not a shallow mount. and it claims it can handle 400 watts RMS. rockford is known for its subs, so I wouldnt think handling deep bass would be an issue.
 
#6 ·
Check gain and equalizer settings first, then move on to the box. How was the gain set and is there any boost of any kind involved? How do you know for sure what the amp puts out? Did you by any chance use a voltmeter to set the gain, and if so did you use a calculation for the 420 watts that you believe the sub puts out or for what it's actually rated at by the manufacturer? What type of equipment do you have in the rest of your system? Is only the sub amplified or are the front speakers too? Have you high-passed the front speakers properly? Where is the sub crossed over in relation to the rest of the speakers?

I am not a box expert but I can tell you if your settings may or may not be an issue. May also get some useful info in the audio section.
I have a Rockford Fosgate bass boost remote which controls the boost (which is usually set fairly low) and I have the gain set at roughly 5, which is halfway turned up.

I know its 420 watts RMS, because rockford gives you a data sheet with all their amps which shows the true RMS watts it puts out.

I have Alpine Type S speakers in front and back powered by the Alpine KTP-445 power pack, which is 45 watts X 4 to each speaker, and I have a high pass filter for the speakers which cuts out freq. below 80 Hz.

As far as "crossing over" the sub, I basically hooked up the sub to the amp and headunit and went for it. Is their something else I have to do?
 
#7 ·
Just like you have a 80hz filter for the front speakers, you also need to activate a "low pass crossover" for your sub. It can be found on the amp marked "X-Over". Put it at 80-90hz. Also, keep your finger off of that bass knob you were talking about. That knob only boosts frequencies around 40hz. Not only does it sound bad, you run the risk of messing up a speaker.
 
#8 ·
I sense a few problems here.

Those subs need to be low passed. Part of your problem, if that sub is also trying to play mid/high frequencies there may be some nastiness happening in your car in the 80-200 HZ range as a result of the frequency overlap where there shouldn't be any. Cross the sub over around 80 HZ.

I'm guessing too much boost may be a problem, and you need to verify that your gain is where it should be. How did you come to the conclusion that '5' is the right place?

Does your head unit have subwoofer controls and if so where are they at? Where's the amp's bass boost at. Where's the bass boost on the head unit at. I could care less what any manufacturer tells you, the bass knob is not to add more boost on top of other boost. It's to add an extra control at your finger tips to level match your bass to the rest of the frequencies by cutting it appropriately. Ideally you want it to be adjusted so the max volume is where you've tuned everything else to play clean, then cut from there. If you're running some bass boost in your system do it at one place in the system and only one, don't stack them. What I normally like to do is cut sub volume at the head unit slightly then use a slight boost at the amp. But my HU EQ stays flat.

Every time you boost something you have to notch the gain back a bit to compensate. Better to set the gain taking into account whatever boost or EQ you will use then set it first then boost from there.

I think you are really just clipping the crap out of that sub.
 
#9 ·
I would look at the box itself and and is it within spec for the sub. the optimal size for your sub in a sealed box is 0.5 to 0.75 cubic feet. I have 2 p2's in my truck and they sounded like crap until i matched the sub to the box and now they sound great. If you go to the rockford website and find your sub and at the bottom of the page they have a box advisor tab that will tell you the size of box you need.

Andrew
 
#10 ·
Buy a Pioneer Sub... LOL
 
#11 ·
yeah box specs are spot on. 0.67 ft for a sealed box. and the amp has a low pass filter on it which I set at 250 hz, so anything above that is cut out. I think I may have some kinda air leak somewhere, so Im gonna recheck all the screws and silicone. It definietly isnt "clipping," its very light distortion/flapping air noise. And my bass on my HU is set at 0, so theres no additional boost to the sub.
 
#12 ·
and the amp has a low pass filter on it which I set at 250 hz, .
You have several people telling you to do it at 80hz. It may not be a direct relation to your "flapping" problem, but subs dont need to be run much over 100hz anyway. You are drawing the sound towards the rear with such a high cutoff.
 
#13 ·
Hey guys,

I recently installed a 10" P3 Rockford sub, powered by a RF 300-1 Punch amp. (acutally puts out 420 watts RMS, despite being rated at 300). I installed it in a sealed enclosure, put silicone on all the joints, used wood glue, etc. to make sure it was airtight...however when I listen to music with heavy bass and low frequencies I get a fair amount of distortion ( kinda like a vibration/flapping noise) Now I know 10" subs and sealed enclosures arent ideal for synthetic bass like in rap/hip hop, but I was just surprised at the distortion. Is it possible the box isn't airtight like I think it is? Most all other music sounds perfect, but I was a little dissapointed when listening to music with the heavier bass.

(I attached some pics of the setup)

First off low end bass isnt gonna work out of a 10. They are not made to catch frequencies that low and if you have the amp adjusted to try it wont carry and all the voice coil can do is basically vibrate. I wouldnt go any higher on your frequency output on your amp then 75 to 80hz. Also I would suggest checking the gain on the amp. Bass amps tend to put out mix ohm ratings and watt push anything higher then half throttle.
Finally I would suggest going to a larger sub if you could and maybe a few series up.
 
#14 ·
First off low end bass isnt gonna work out of a 10.
Thats a matter of opinion. 10's can play just as low and loud as any 12 or 15. If you take a look at the graphs of some of the higher end 10's, they have similar curves @40hz and below as some 12's. Set up correctly, 10's are just as efficient at producing lower bass notes than 12's.

I have a 10", and while it may not rattle any windows, it can play very cleanly down to 25-30hz...*without* distortion.
 
#15 ·
Thats a matter of opinion. 10's can play just as low and loud as any 12 or 15. If you take a look at the graphs of some of the higher end 10's, they have similar curves @40hz and below as some 12's. Set up correctly, 10's are just as efficient at producing lower bass notes than 12's.

I have a 10", and while it may not rattle any windows, it can play very cleanly down to 25-30hz...*without* distortion.
As I highlighted what you said.. Im not degrading 10s in my opinion they have a much cleaner sound then 12's and 15's Im just pointing out what I know and that is to get low end bass out of economical speakers and not spend a weeks worth of a paycheck on a sub its better just step up to a larger speaker.
I unfortinately am a stickler on sound and have spent well over 10 grand on audio in my truck alone. Not everyone is like that.
 
#16 ·
As I highlighted what you said.. Im not degrading 10s in my opinion they have a much cleaner sound then 12's and 15's Im just pointing out what I know and that is to get low end bass out of economical speakers and not spend a weeks worth of a paycheck on a sub its better just step up to a larger speaker.
I unfortinately am a stickler on sound and have spent well over 10 grand on audio in my truck alone. Not everyone is like that.
The 10" in my truck was about half the cost of the OP's sub. Even some higher end subs are in the $100 price point.
 
#17 ·
The 10" in my truck was about half the cost of the OP's sub. Even some higher end subs are in the $100 price point.
I need the link to these pages. Im not quite sure what we are considering high end for $100.00 but if they are what i'm thinking please mail me where I can start buying them in bulk cause I can make one hell of a profit down here.
 
#18 ·
#19 ·
If a proper crossover setting doesn't improve the sound what about tinsel slap? When the tinsel leads hit the cone during high excursion. Should be an easy fix if so.

sidenote: i can't see the point in spending big money on a subwoofer as it only plays from 20-63 Hz (in my case). I'd rather spend the cash on high end mids.
 
#20 ·
If a proper crossover setting doesn't improve the sound what about tinsel slap? When the tinsel leads hit the cone during high excursion. Should be an easy fix if so.

sidenote: i can't see the point in spending big money on a subwoofer as it only plays from 20-63 Hz (in my case). I'd rather spend the cash on high end mids.
sorry but what exactly are tinsel leads? and to Brandon1, I think I will lower the crossever freq. to about 100 and see how that changes things.
 
#22 ·
Andylax: I just installed a memphis S class 12 in my truck and a first it was great and then I started hearing the SAME sound that you are describing. I knew there was no way that I had blown the sub. I knew the sub wasn't bottoming out either because I had the volume at like 60%. I did consider tinsel slap, but I am by no means no expert in the audio world, so I asked around and called some local audio dealers, and they told me with my sub it would sound like that for about 6-8 hours of playing time. For me it was because the spider?(Can't remember exactly what he said), but he said the spider or something was stiff where it was brand new, so he told me to just play it at about 50-65% volume for a few hours and it would go away after it had been broken in. I hope this helps, I got a new 370z so I have been driving it a lot more than my truck, so it may be a while before I get 8 hours of playing time on the sub, but I will keep up with how long I listen to it, and after 8 hours or so I will let you know if it went away for me or not.
 
#23 ·
Update******

I found the culprit behind my sub sounding terrible. They sub actually tore the box apart at the seams. The seams have actually began to come apart on the box. I have college orientation tomorrow and wednesday, so thursday I will use some silicone and also use the air nailer and nail it back together and see if that fixes it. Andy, try pushing the center of your sub down while its off and listen carefully for air "whooshing" out. I hope this helps.
 
#24 ·
Update******

I found the culprit behind my sub sounding terrible. They sub actually tore the box apart at the seams. The seams have actually began to come apart on the box. I have college orientation tomorrow and wednesday, so thursday I will use some silicone and also use the air nailer and nail it back together and see if that fixes it. Andy, try pushing the center of your sub down while its off and listen carefully for air "whooshing" out. I hope this helps.
thanks man. I feel like its definitely some air leak somewhere, but I used wood glue, pre drilled all my screw holes (to prevent the MDF from splitting), used plenty of silicone on all the joints...maybe air is leaking where the lip of the sub rests on the box?? Ill try pushing on the sub and see if I hear anything.
 
#25 ·
Good Luck dude! I hope you figure out what it is!!
 
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