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-   -   Car subwoofer sounds muddy but hits low bass well (sluggish bass) (http://www.diyaudio.com/forums/subwoofers/214941-car-subwoofer-sounds-muddy-but-hits-low-bass-well-sluggish-bass.html)

dannyjmf 22nd June 2012 01:47 PM

Car subwoofer sounds muddy but hits low bass well (sluggish bass)
 
9 Attachment(s)
hi ...

i've completed a subwoofer system with 12in subwoofer for my car use. Initial testing indoor using a normal quality car amplifier (used for my PC system) the bass is tight and well controlled.

Problems rise when it is used together with my car amplifier which has bass boost at 45Hz and i set it at a mild boost of 4dB. The amplifier setting of the crossover is at 85Hz. The sound of the bass hits very low frequency but it is not tight when playing techno or dance tracks with very fast beats ...:(:confused:

The amplifier is connected to a parametric preamp which has subwoofer controller.

I here also attached the graph of the predicted frequency response by WINISD, photo of the completed subwoofer, amp photo and specification.

I wonder if my box is not properly designed or my car amp have damping factor issues.

thanks for advices and solutions to my problem

sreten 22nd June 2012 02:04 PM

1 Attachment(s)
Hi,

Tune your box a lot lower or go sealed for in car use. The mud is probably
the inevitable bass overload you will get below the port tuning frequency.
Tune it down to between 33Hz and 38Hz.

55L is a big box for sealed giving a low Q of 0.47. Tuning the box to 26Hz,
an octave below the current tuning, will be better than sealed IMO here.

rgds, sreten.

chlorofille 22nd June 2012 02:07 PM

Sealed subs are normally faster and less muddy for car use. Try stuffing the port completely and see how that goes.

Hey Danny, I'm from JB but now living in NZ. Nice to see a fellow M'sian here!

lduarte1973 22nd June 2012 02:11 PM

Quote:

Originally Posted by chlorofille (Post 3068668)
Sealed subs are normally faster and less muddy for car use. Try stuffing the port completely and see how that goes.

I did that at home , huge difference for the better

dannyjmf 22nd June 2012 02:42 PM

Quote:

Originally Posted by sreten (Post 3068664)
Hi,

Tune your box a lot lower or go sealed for in car use. The mud is probably
the inevitable bass overload you will get below the port tuning frequency.
Tune it down to between 33Hz and 38Hz.

55L is a big box for sealed giving a low Q of 0.47. Tuning the box to 26Hz,
an octave below the current tuning, will be better than sealed IMO here.

rgds, sreten.


Ok lower the tuning frequency. But i tried the subwoofer system before using another car amp which is used for my computer subwoofer (DIY sub also) and the bass there is tight. The amp signal feeds from a custom made bass boost circuit peaking high pass filter.

The previous version of my car subwoofer (i sold off already) also have the same issue when using the car amp the bass sound sluggish and using another amp it sounded tight and nice ...

sreten 22nd June 2012 02:51 PM

Hi,

A computer sub amp may have a bass roll-off to suit a boom-box bass
alignment, but it won't go deep, it probably doesn't even try to do that.

It depends also on whether the bass boost is just a 2nd order peaking EQ,
or a 2nd order peaking high pass filter what low bass distortion you will get.

rgds, sreten.

dannyjmf 22nd June 2012 02:55 PM

Quote:

Originally Posted by sreten (Post 3068664)
Hi,

Tune your box a lot lower or go sealed for in car use. The mud is probably
the inevitable bass overload you will get below the port tuning frequency.
Tune it down to between 33Hz and 38Hz.

55L is a big box for sealed giving a low Q of 0.47. Tuning the box to 26Hz,
an octave below the current tuning, will be better than sealed IMO here.

rgds, sreten.


Ok lower the tuning frequency. But i tried the subwoofer system before using another car amp which is used for my computer subwoofer (DIY sub also) and the bass there is tight. The amp signal feeds from a custom made bass boost circuit peaking high pass filter.

The previous version of my car subwoofer (i sold off already) also have the same issue when using the car amp the bass sound sluggish and using another amp it sounded tight and nice ...

dannyjmf 22nd June 2012 03:08 PM

Quote:

Originally Posted by sreten (Post 3068737)
Hi,

A computer sub amp may have a bass roll-off to suit a boom-box bass
alignment, but it won't go deep, it probably doesn't even try to do that.

It depends also on whether the bass boost is just a 2nd order peaking EQ,
or a 2nd order peaking high pass filter what low bass distortion you will get.

rgds, sreten.




Forget to mention ... the amp for the computer system which i used to test my New subwoofer is actually a Diy 4 channel 25W LM1875 based amp. 2 channel were bridged to test the subwoofer. And the bass boost module is also a DIY system build to suit my subwoofer system. The boost is around 4db @ 45Hz using peaking high pass 2nd order Peaking filter. Low pass was crossed at 85hz cutoff. I even tested it with another spare car amp i have it sounded tight and nice.

Brian Steele 22nd June 2012 04:25 PM

1. Fb is too high. 50 Hz? That's way too high. Try 30 Hz
2. Remove the bass boost @45 Hz.
3. Try orienting the box a bit differently in your car.
4. What LP filter are you using on the subwoofer? 80 Hz? Try a higher frequency. The rear seat in a sedan can act like a natural LP filter. Now add to that the LP filter on your subwoofer amp and possibly the LP filter on your deck or EQ and the effect of the driver's Le, and the end result may be that the subwoofer is simply being effectively filtered at too low a frequency for car audio use.

For some background, I use 2x12 (sealed) subs in my car. The LP filter on my deck is set to 125Hz, 12dB/octave, and on the amp 200Hz/24dB/octave. And I drive an SUV, so no "rear-seat LP filter" to worry about. Le for the subs works out at 1.5mH at a 2 ohm load.

OscarS 22nd June 2012 06:16 PM

I completely agree with Brian. If you need "bass boost:", then you just don't have enough subwoofer or amp, period. Tune that box right (low 30s), bump up the LPF to 100 or 110. Or just get a different amp. Remember, we just can't hear what you're hearing and can only go by your description, which can mean different things to us.

It partially sounds like you've made up your mind about the amp. So just replace it. Gotta pay to play in this game. Otherwise you're left with modifying your system in the other ways that have been described.


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