Tuning

[rob420]

Can Tuning a port lower than what the sub manufacturer recommendation harm the sub? I got a Memphis M515Q1 it is recommended to be tuned at 43hz. I recently built a box at the required size, but did a port at 35hz, so I could pick up some lower bass (Had the amp set at 35hz). It worked good for about a week than I noticed the sub slapping. I turned the amp down and turned the hz on the amp up to 40hz to eliminate the slapping at high volume sounded good, for about 30 min than it fried. Wondering if the port tuning had something to do with it? (Amp is a Rockford Power 1500 running at 1 0hm, 1880rms)

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[fasfocus00 5,000+ posts]

it shouldn't unless it's below the speakers frequency range.

 

[bowhunter 10+ year member]

Your sub blew cause you more than doubled the rms rating... I believe that sub is rated at 800 rms

 

[garretttt4 10+ year member]

Your sub blew cause you more than doubled the rms rating... I believe that sub is rated at 800 rms

This.

 

[rob420]

Sub is rated at 1850 rms

 

[Milk Mayne 10+ year member]

Clipped to death?

 

[Full Tilt 10+ year member]

Sub is rated at 1850 rms

Where'd you get that information?

M5 Subwoofers from Memphis Car Audio

It clearly says under 'Specs' that the 15 is rated at 800w RMS. You gave that sub way more than it should've had to handle. You could power two of them with that amp and still be overpowering them by a little bit.

 

[IonRL205 10+ year member]

Sub is rated at 1850 rms

1000 rms and above is pushing it for a 2.5" vc thermally

If the sub was slapping it was because you were bottoming out, due to playing too low of a freq with that power you're putting out

 

[Milk Mayne 10+ year member]

Guys, I think he's got the quad coil 515, the Mojo. Which from what I understand is rated at 1750 rms. I'm still going with clipped to death. Then again, I could be under the wrong impression too.

 

[mrclean636 10+ year member]

Can Tuning a port lower than what the sub manufacturer recommendation harm the sub? I got a Memphis M515Q1 it is recommended to be tuned at 43hz. I recently built a box at the required size, but did a port at 35hz, so I could pick up some lower bass (Had the amp set at 35hz). It worked good for about a week than I noticed the sub slapping. I turned the amp down and turned the hz on the amp up to 40hz to eliminate the slapping at high volume sounded good, for about 30 min than it fried. Wondering if the port tuning had something to do with it? (Amp is a Rockford Power 1500 running at 1 0hm, 1880rms)

My input:

1. 43Hz is their tuning for max "SPL" on the meter. For street beating. you can always tune lower, ideally to your favorite area. You have to make sure that the subsonic filter on the amplifier is set, around your tuning frequency, you don't want it all the way down or off. If your Rockford Fosgate amp is like the rest then there should be a "infrasonic filter" with an on and off setting, this is Rockford's "subsonic filter". If the box is ported you definitely should have that on, it sets the filter to 27Hz I believe.

2. Now... you can bottom out a sub multiple ways. Too big of a box, too much power, no subsonic, poor tuning, distortion (which causes a smelly sub), etc. Let's say you listen to music that has notes of 40Hz, and your box is tuned to 35Hz, you will have no problem playing that note at high volume. Now if you were to have a song that has notes of 25Hz, and your box is tuned to 35Hz, you risk bottoming out the sub. A subsonic filter helps prevent that but only so far. The lower Hz tracks generally cause more excursion on the sub and having the volume cranked can cause stability problems with the motor.

3. You should really tune the amp with an oscope of DD-1 next time, if you didn't this time. It will allow you to set the max un-distorted gain on the amplifier. That way you know you aren't clipping the sub. But if you play some ****** slowed and boosted youtube song rip, at like 96kbps, you are going to clip. If you smell the sub, you have already done damage, turn it down.

I hope your sub is under warranty btw, that *****, this whole hobby is a learning experience from day 1. No one knew everything at the start!

 

[rob420]

The sub is the new 2012 mojo 15" quad voice coil 1 ohm, not the M5 misprinted that above. The box is a little over the recommendation of 5.25. The amp never clipped at the setting in the prior box, which was 3.5 cuft or slapped, not sure what the port was tuned at. I ended up frying the voice coil still plays to some extent. Sending it out tomorrow for a new one under warranty. My port maybe an issue, not sure new to this tuning thing. Prior to this sub all my other mojos had a 2" wide port at the length of the box not sure how far it dropped in they always slammed with no slapping. I used the re box calculator and ended up with a port 4.75" wide 19.5" high and 15.75" with an 8" 90 degree angle. The box externally measures 21" high 30" wide 23" deep. Tuned at about 36hz. I believe the port ratio was 9:1. Sub facing up port on back. Is it possible its getting to much air? Was thinking about chopping the height down and doing a port running with the length at a smaller diameter on the lower back of box, as a possible fix. Already, chopped the box once due to being to big, figure I could do once more before having to buy more MDF. No car audio places have the tools to check if my amp is set correctly around where I live to rule the amp out. Thanks for all the feed back it is greatly appreciated

 

[mrclean636 10+ year member]

The sub is the new 2012 mojo 15" quad voice coil 1 ohm, not the M5 misprinted that above. The box is a little over the recommendation of 5.25. The amp never clipped at the setting in the prior box, which was 3.5 cuft or slapped, not sure what the port was tuned at. I ended up frying the voice coil still plays to some extent. Sending it out tomorrow for a new one under warranty. My port maybe an issue, not sure new to this tuning thing. Prior to this sub all my other mojos had a 2" wide port at the length of the box not sure how far it dropped in they always slammed with no slapping. I used the re box calculator and ended up with a port 4.75" wide 19.5" high and 15.75" with an 8" 90 degree angle. The box externally measures 21" high 30" wide 23" deep. Tuned at about 36hz. I believe the port ratio was 9:1. Sub facing up port on back. Is it possible its getting to much air? Was thinking about chopping the height down and doing a port running with the length at a smaller diameter on the lower back of box, as a possible fix. Already, chopped the box once due to being to big, figure I could do once more before having to buy more MDF. No car audio places have the tools to check if my amp is set correctly around where I live to rule the amp out. Thanks for all the feed back it is greatly appreciated

No problem. The recomended box spec for that sub, according to the Memphis box spec document (Memphis Box Spec Document) the NET volume of the enclosure after all the displacements should be 3.8 cuft minimum to 4.30 maximum. Putting your dimensions into the Torres Box Calculator your gross volume is 6.91 cuft, and then entering your port in there it goes down to 3.64 cuft net. Then subtract the sub displacement and any additional bracing displacement and it goes down from there. Your port might honestly be a little big too.