Chesty nasal sound

[rhapsodee]

Hi guys,

I'm hoping to get some advice on possible causes and remedies of a nasal / chesty quality from a center speaker.

It is a Legacy Audio center speaker that i got second-hand, supposed to have retailed at more than 1k new.. I had opened it up previously to add some foam and stuffing, it did help the problem slightly, however it is still rather obvious and unpleasent.

The enclosure is very solidly built 3/4 in MDF, with two shelf bracing (this is a regular sized MTM center speaker), using a pair of Vifa woofers and a tweeter. The crossover looked very well built, almost like a hand assembled DIY design, with quality inductors and capacitors.

Guess what i'm trying to say is that the nasal / chesty sound is definitely not because of a poorly constructed, resonant cabinet, crappy drivers and a cheap crossover.

If so, what could be the cause, and how do i begin to try and fix it? I will try to get pictures and specs posted.

Thanks!!

[wakibaki]

This sounds like something really pronounced, like a broken or faulty driver.

Either that or it's something miniscule that you're exaggerating out of all proportion.

Has a particle fallen into a driver somewhere?

w

[rhapsodee]

Hmm, not broken or faulty, just that vocals in movies and 5.1 audio have a chesty and nasal colouration. Does not sound neutral and natural, as in a real voice.

I would imagine it to be related to a uneven or frequency response, as if a certain frequency is particularly prominent.

Could this be due to a particular driver resonance not filtered out using a notch filter?

[planet10]

I often find that this is caused by time-smeared reflections back thru the cone... post a picture?

dave

[rhapsodee]

Hmm, i thought so, hence tried lining the rear and side walls with egg carton foam, as well as slighly increasing the stuffing in the enclosure. Helped a little, but the problem is still there.

Will post pics as soon as i can.

[planet10]

It can also be reflections off the basket or the driver cutout. How close are the box walls to the driver.

dave

[Un-filtrd]

Originally Posted by rhapsodee

If so, what could be the cause, and how do i begin to try and fix it?

Where do you have the speaker located? Is it in an A/V console or entertainment center? Is it close to any boundaries? Is it positioned below ear level?

[ashok]

Did you try reversing the phase at the speaker terminals ( of the center channel )? If it's causing a bass hump it should reduce this. If it now sounds OK just leave it or introduce an 'informed' bass roll off with normal polarity!

[rhapsodee]

It's just on top of the console infront of the LCD tv. Previously it lived on top of a rear projection tv. Same problem. Don't it's due to location.

Will try the polarity. I thought the cancellation generally results in no bass.

Do woofers need notch filters? In what circumstances?

[GM]

Originally Posted by rhapsodee

I'm hoping to get some advice on possible causes and remedies of a nasal / chesty quality from a center speaker.

'Chesty' = pronounced mid-bass (~128-896 Hz), so a higher F3/lower Q is normally the fix.

'Nasal' = mids distortion (~896-2560 Hz), so depending on the driver's/XO's combined response, raising F3 may solve it all or you may need to also insert some amount of 'BBC dip' to tonally balance it all out with the trade-off being potentially some loss of the high speech intelligibility that the center is mainly there for.

GM