Stereo question

bobthetj03

bobthetj03

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I have a Kenwood HU. It has a 13 band equalizer and crossover settings. I'm running Polk DB525's front/rear and a sub in the center console powered by a small mono block amp. the amp has a LPF frequency setting and a gain setting. My question is, do I use the amp LPF frequency setting to set the sub, or do I open up the setting to let all frequencies thru and adjust them thru the HU crossover? The way I have it now I have the amp LPF frequency set around 70db. and the HU crossover set to "through" which allows all frequencies thru. The amp is under the dash, so making adjustment changes is not easy, so that is why I'm considering using the deck for adjustments.
 
Both the head unit and the amplifier should have cutoff curves listed in their literature. I would go with whichever one has higher, or if the slope is at or over 24 db, I would just go with the head unit for convenience.

You should not use both at the same time, because they tend to retard the timing of the waves, and could result in cancellation around the cutoff frequency relative to the speakers.
 
Also what size speakers and subs are you running? By 70 db, I assume you mean 70 Hz. That is a rather low cutoff frequency except for very large subs. 100-120 is a good crossover frequency for most small systems.
 
Steel City 06 said:
Also what size speakers and subs are you running? By 70 db, I assume you mean 70 Hz. That is a rather low cutoff frequency except for very large subs. 100-120 is a good crossover frequency for most small systems.
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Yes, I meant 70 Hz. It's an 8" slimeline sub.

Steel City 06 said:
Also make sure you're using the High Pass Filter (HPF) on the speakers. Speakers cannot play below 80-100 Hz effectively.
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The HU has HPF adjustments for the front/rear speakers. I have it set to "through" right now. It can adjust from 30 Hz. to 250Hz. There is also a slope adjustment and a gain adjustment. Have no idea what to do with those two.
 
You should use the deck. There is no other simple way to match the HPF of the main speakers to the LPF on the sub. You should match the HPF to the LPF if that makes sense. The frequency and slope should be the same so you don't get dead spots. It doesn't really matter where you set the gain as long as you don't do anything like have one max and the other min.
 
pagrey said:
You should use the deck. There is no other simple way to match the HPF of the main speakers to the LPF on the sub. You should match the HPF to the LPF if that makes sense. The frequency and slope should be the same so you don't get dead spots. It doesn't really matter where you set the gain as long as you don't do anything like have one max and the other min.
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The slope adjustment is from -6db to -24db. I'm not sure I know what you mean by matching the HPF to the LPF.
 
Also, would I be better off using the gain adjustments vs. the fader control? I have the pods toned out since they are so close to my ears.
 
cliffish said:
I am in same boat and have been playing with settings I don't understand for 4 months. I really miss the old days where there was just a slide on a graphic equalizer.
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My HU has a 13 band equalizer, so I've been playing with that as well. It has presets, none of which I like, so I have a basic smiley face on the manual EQ and use it.
 
If your HPF is set to -6db then your LPF should also be set to -6db. If you set your LPF to 120 hz then set the HPF to 120 hz as well. If they don't match you can create dead spots. If I was setting up everything I would set all the faders and gain on the deck to "zero" or neutral and then adjust the gain on the amp once so it sounds close to correct. Then button it all up and fine tune it at the deck. When you first set the filters, HPF and LPF keep the eq zeroed out. Same when you set the gain on the sub. Then use the fader to get front-back close and finally play with the eq when you are all finished. At least that's how I'd do it, interwebs grain of salt and all.
 
The high pass filter removes low frequencies from the signal sent to the speakers. It should be used to reduce over-excursions of the speaker woofer cone.
The low pass filter removes high frequencies from the subwoofer signal. It should be used to prevent the subwoofers from attempting to play high frequency signals, which it cannot do accurately.

The slope describes how much the signal is attenuated above the cutoff frequency for a LPF or below for a HPF. With a -6db cutoff slope, the sound will be attenuated 6 dB per octave above the cutoff frequency.
 
Personally I prefer to use 24 dB/octave on al of my equipment. 12 can also work.

The HPF/LPF should be set close to each other. Some overlap is okay, but not necessary. For example I set my HPF to 100 Hz and my LPF to 120 Hz. The reason for the overlap is because there is a small amount of attentuation even before the cutoff frequency is reached.
 
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8DD189AC-564C-4786-9AF7-F7388C9F6CAE.gif

This is a cutoff curve for a (unknown type) filter I pulled from Google. The slope describes how quickly the signal is attenuated below a certain frequency. Note that even at the crossover frequency there is still some attenuation.

I’ll see if I can find a better picture.
 
Higher cutoff slope requires less overlap because it is sharper. I used 24 db with both high and low set at 80 Hz in my last system
 
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