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Hello ,

I will be running two sealed boxes with JL audio 12W3-3-2 subwoofers, and 1 ported box with a JL audio 12W7-3 when the subwoofer boxes are completed . I will also be post pictures when their done.

After a little research and additional information from another home theater shack member . I found that my Crown XLS2000 has a built in high pass 20HZ filter that cant be off per Crown tech support.

Can the dspmini some how defeat this high pass filter?


Is their crossover network that goes in between the crown amplifier and the Subwoofer that would allow them to reach frequencies below 20 hertz ?

Read more: http://www.hometheatershack.com/for...y-home-theater-subwoofer-3.html#ixzz2Xfeyj5fs
 

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It depends on where in the circuitry that high-pass filter resides. If it is entirely the result of a series input capacitor, you can connect a larger value capacitor in parallel with it to lower the high-pass cutoff frequency. With a Class D amplifier, that high-pass function could be buried in other parts of the design, and then you would be stuck with it. Definitely a job for a skilled tech, warranty voided, risk of death & destruction, etc.

The XLS 2000 spec says -1 dB at 20 hz, so the -3 dB point would be about 10 Hz, and -6 dB at about 6 Hz, just so you know what you are really dealing with.
 

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I think whit -3 db at 10 hz it,s not a point.
The Xmax at 10 hz will be 4 time,s as a 20 hz tone,so i think that will compensate it.

I would build it ,measuere it,maybe after this, if your output below 20 is not ok thinking about modding the amp.
 

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And no, you can't "undo" an HPF by using another device earlier in the signal chain. There is no such thing as a reverse filter and it would be problematic for a variety of reasons. The only way to get rid of the HPF would be to modify the amp or to use another amp altogether.
 

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Using another amp would be easiest. But if you can't you can use an external EQ and add eq so that the Hpass is not effective. It is how most people get around having a 10hz Hpass on most amps.

I am not a big fan of others modifying amps but if you are capable then sure go ahead. But I would use work arounds instead or buy another amp with 10hz Hpass.
 

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And no, you can't "undo" an HPF by using another device earlier in the signal chain. There is no such thing as a reverse filter and it would be problematic for a variety of reasons. The only way to get rid of the HPF would be to modify the amp or to use another amp altogether.
I thought if you, for example, put +3dB at 20hz before the amp and the amp has a -3dB filter at 20hz, the result would be 0dB
But I'm sure the phase/group-delay would be affected!
 

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You would also be amplifying noise, which to me is the biggest issue. Sure at -3dB you could add 3dB, at which point a .1V noise blip would become a .2V noise blip. But then what about where you're gaining +10dB and so forth? What about when you get to the point of amplifying the noise floor up to your reference level? As you get farther out into the slope the noise would be more and more amplified, killing your SNR and adding susceptibility to other issues.
 

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The simple way of looking at this is: When you EQ your system, if your bass is lacking in the 10 to 20 Hz frequency range, go ahead and boost it a little, assuming your EQ device or software will allow you to. You never want to boost very much at any frequency, and never at a room node, but a small boost - say 2 or 3 db around 10 Hz, knowing the nature of what caused it - to pump up that gradual rolloff a bit - would be fairly safe. Only as the need is indicated by measurement data, and with care, as other have warned.
 
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