weird loss of output at specific frequencies

[Beatin' 10+ year member]

I have a pair of radio shack 15's (yeah lolol whatever...) in a sealed Atrend prefab enclosure, in side the trunk of my car.

Even when the EQ is flat, no bass boost, etc, there are songs I listen to that have sine wave bass notes (southern rap music) that are no where near as loud as the real lows and highs. I see the waves on the oscilliscope in the windows media player and they are heavily amplified like other bass notes within the track. So this is not a case in which certain bass notes were recorded softer than others.

If not that, then what may be the cause of this loss of SPL?

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[ThatChevyGuy 5,000+ posts]

It's the subs and the enclosure those subs will probably drop off pretty quick under 40 hz

 

[TaylorFade 10+ year member]

It's the subs and the enclosure those subs will probably drop off pretty quick under 40 hz

That was my first thought too, but he said "the real lows" and the highs. Like, there's a hole in the response other than the rolloff. Of course, I'm assuming his definition of real lows is like sub-35hz or so.

I wonder if maybe the box is big enough to catch low end well, but impedance rise is killing him in the 40-50hz range? Or his cabin gain is working overtime down low. Or conversely, causing cancellation in whatever range he's lacking.

 

[Chriszle 10+ year member]

I can think of two possible problems. The subs and the box.

 

[TaylorFade 10+ year member]

I can think of two possible problems. The subs and the box.

Those are the obvious ones though. Would be interesting to know (or think about) what's going on outside of those. Lol.

 

[Beatin' 10+ year member]

Is there any other information I can give to help solve this problem?

 

[Chriszle 10+ year member]

You can check your crossover settings on amp and/or h/u. If they are set correctly, you should try moving your box in all sorts of configurations. Sealed boxes should have less low end roll off than ported, so you shouldn't be missing the lows.

 

[Beatin' 10+ year member]

the LPF on the amp is all the way up at 200hz and the HU is set at 160hz. But that's not the range in which loss occurs. The loss I'm experiencing is, I'm gessing, in between 50-80hz.

I have the box sitting deep in the trunk facing backwards (ie: open the trunk, subs in your face). You think moving the box towards the trunk lid will help?

 

[av83 10+ year member]

the LPF on the amp is all the way up at 200hz and the HU is set at 160hz. But that's not the range in which loss occurs. The loss I'm experiencing is' date=' I'm gessing, in between 50-80hz.
I have the box sitting deep in the trunk facing backwards (ie: open the trunk, subs in your face). You think moving the box towards the trunk lid will help?[/quote']

Leave the lpf on the amp up or off, and turn the lpf on your H/U down to 80, at the highest. You should be attempting to reproduce frequencies above 100 hz with your interior speakers.