Need crossover and other suggestions for center channel

[dmy19]

I recently replaced the center dash-mounter speaker in my car and the sound is too bright and the highs too harsh. It is also loud and a little overbearing. I am looking for suggestions to tame the sound. I really like the center speaker because it fills an apparent void (I miss it when it's disconnected) yet it just doesn't sound right. The center speaker is a coaxial Polk db351. The factory speaker that I replaced was a 4 ohm 3.5" paper cone speaker. The center channel is powered by the factory radio and there is no way to adjust its volume.

I tried to lower the volume by wiring in a 4 ohm resistor in series with the speaker. It brought the volume down some but I understand that this changes the sound. My current options are:

1) Clip the tweeter wire on the tweeter so I only have the woofer (mid?") playing

2) Install an L-pad / driver attenuation circuit to properly reduce the volume without messing with the sound

3) Install a bandpass crossover/filter on the speaker - I do not know what frequencies I would need to filter and what slope would be best however I am open to building my own

4) Combination of #2 and #3

5) I have no idea - open to suggestions! (I already tried reversing the wires for phase)

Before we go any farther I know that I am supposed to have a sound processor to figure out what goes to the center speaker but me and my budget are just not on that level!

Some back story: I recently installed a set of Polk DXi6501 component speakers in the front of my car. The woofers and tweeter went in their factory locations - woofers in the doors and tweeters up in the dash up by the windshield. I am running them off of a Kenwood KAC-M3004 amp that is giving the speakers up to 50W RMS x 2 @ 4 ohms. That setup on its own sounds pretty good. I'm not used to having good tweeters so that is taking some getting used to. I also have two factory-installed 8" subs in the rear shelf that are now driven by the Kenwood amp getting up to 75W RMS x 2 @ 2 ohms.

I am open to suggestions. I feel like #1 is a too good to be true scenario. I like #2 and #3 but I don't know how many decibels to attenuate, what frequencies to filter, and what slope to use. Any help around that would be huge.

Thanks in advance!

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[trumpet 5,000+ posts]

A center channel should be playing treble up through 20 kHz. I would not disconnect the tweeter. Perhaps a 1st order crossover to give a gentle roll-off on the upper end would help, but you really ought to measure what that speaker is playing to see if there is an offensive hump that's causing the harsh and overbearing sound.

You could try CDT's LP-1 L-pad to cut back the volume. This is what they use in the Image Enhancement Kits. CDT Audio Image Enhancements

 

[dmy19]

Thanks for the reply!

The only audio monitoring equipment I have is permanently attached to either side of my head so I think measuring is out. //content.invisioncic.com/y282845/emoticons/smile.gif.1ebc41e1811405b213edfc4622c41e27.gif However, I do have a tone generator on my phone. If I let it play up through the range, say from 200 Hz through 20 kHz, would I notice the increase in sound?

I will look into the L-pad.

Can you [or anyone else] suggest some bandpass crossover points and slope for the 3.5" coaxial speaker? I can hear it clearly distorting on bass drum hits and I know it needs attenuation in the higher frequencies as well. This center channel adds a third tweeter to my dash which is overkill IMO.

 

[trumpet 5,000+ posts]

Search your app store for an RTA app. Then get a 20 Hz - 20 kHz correlated pink noise test track. Together you can see a response graph of your vehicle in real time. Hold the phone close to the center speaker.

If you do this please share your result.

 

[Papermaker85 5,000+ posts]

I've bet it's reinforcement from the windshield that's causing it it's a simple little trick to test take a dish rag and tape it on the windshield directly above the driver in question and try again and see if it don't damping the sound report back

 

[dmy19]

Thanks again for the replies, guys.

Okay, I downloaded the RTA app on my phone. I got a 5 second 20 - 20,000 sweep... not sure if it's pink noise or what. I got it here, "Sweep1" - Professional Online Audio Frequency Signal Generator. I looked for a while and it's the best I could find. Now what do I do???

I will try that dish towel thing today. The harshness is worst when I am driving and I turn the volume up. That is the same time that I'm introducing road, engine, and exhaust noise into the mix... maybe not a coincidence.

 

[dmy19]

Well I bought the parts to build a 1st order 500 Hz - 3,000 kHz bandpass filter. I also bought an adjustable L-pad. Hopefully I'll be able to dial it in with that!

 

[HardcoreBob]

Well I bought the parts to build a 1st order 500 Hz - 3,000 kHz bandpass filter. I also bought an adjustable L-pad. Hopefully I'll be able to dial it in with that!

****... I was looking forwarded to hearing the results of the "rag absorbing experiment"...

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