Boxy center channel remedy

[wooly]

When I bought my HK avr140, I was advised by HK to turn my center channel louder than the other speakers in my 5.1 system because it's an 8 ohm where the other speakers are 4 ohm.

I discovered something in the mean time. I had been running my system this way for a few months but never liked the boxy sound coming out of the center channel. Now I have it turned down -1 below the rest of the speakers which are at 0 and it sounds so much more natural. The sound is broadened (if that's a good term to use)with a much more even sound stage across the front and voices are as audible as ever with sufficient sound still coming out of the center channel. I'm happy now.

Clear this up for me though. With a 8 ohm center and 4 ohm mains and surrounds, wouldn't it be advisable to turn the center channel down rather than up and not the other way around as I was advised to do?

 

[Nuglets]

Actually you can't tell which one will be louder with a given amount of power just by the nominal impedance(Ohms). You should get a Radio Shack SPL meter and use your receiver's test tones(if it has them built in) and adjust the level of each channel so that meter reads 75dB(for most A/V receiver's) with the master volume at 0.0dB. Once you do that you can make minor adjustments to get it just right. An SPL meter is much better at measuring how loud the speaker is than a salesman who tells you to turn the center channel up because it has a different impedance than the other speakers.

 

[WmAx]

I discovered something in the mean time. I had been running my system this way for a few months but never liked the boxy sound coming out of the center channel.

Well, I'm not sure what you mean by "boxy". But it may be that this speaker has excessive audible resonance(s), primarily due to insufficient internal acoustic dampening material(s). You can correct this problem by adding the correct material(s) to the interior volume.

-Chris

 

[wooly]

Yes, how do I explain "boxy" . But whatever, it's not there anymore.

I really do need to get a SPL meter. Hopefully the Source (formerly Radio Shack in Canada) has them. I'm going to find out tomorrow.

Just out of curiosity, what does one use for internal acoustic dampening material and how much?

 

[wooly]

So I found out that the Source (Radio Shack) here in Canada doesn't carry SPL meters. Radio Shack on line won't ship to Canada. Any others suggestions?

 

[Nestor]

The sensitivity of the speaker (typically measured in db from 1 metre distance and 1 watt power) tells how loud it will play for a given volume setting.

Impedance tells you how much of a load you are placing on the amplifier, which is more of a concern when running multiple speakers.

It sounds to me that you've already solved your problem with a little critical listening and some minor adjustments. Save your money!

 

[wooly]

It would be good to have a SPL meter but I think I have done pretty well with my own ears. I may still get one sometime but I think I'm at the point where I have my system fine tuned to where it sounds pretty darn good.

I put on an ELO Zoom dvd tonite which is a very well recorded dvd and tweaked it a bit more just by listening to the balance of all the speakers. I'm satisfied and I guess that's what matters in the end.

 

[sleeper]

Actually, what the HK rep mentioned is correct advise. All things being equal, a 4ohm load will be louder than an 8ohm load. Again... that's all things being equal.

Since your centre speaker is of a different impedence to your mains, can I assume that they are of different make and model? If not, then I can only assume that the sensitivity of your centre channel speaker is much higher than your mains. That could be why the centre channel sounds more blended in with the mains when you lowered it. He/she did give the correct adivise given the circumstances. The only real way to see if it's good advice is to measure the decibles. But hey... whatever sounds good to you, right?

sleeper.

If you assume, that makes an "a$$" of "u" and "me"...

 

[Josuah]

The sound may be boxy due to vibrational energy transferring onto whatever the center channel is on, or if there are close reflective surfaces because it's on a shelf or inside a closed space.

You can put rubbery things between the shelf and speaker enclosure to decouple the speaker from its shelf or whatever, and make sure the front of the speaker clears the front of anything it might be sitting on or inside of.

 

[wooly]

QUOTE/Since your centre speaker is of a different impedence to your mains, can I assume that they are of different make and model? If not, then I can only assume that the sensitivity of your centre channel speaker is much higher than your mains.QUOTE

Actually the mains have a higher sensitivity than the center. I think they are rated at 93db and the center at 88db. The center is a different make than the 2 mains.

QUOTE/The sound may be boxy due to vibrational energy transferring onto whatever the center channel is on, or if there are close reflective surfaces because it's on a shelf or inside a closed space.QUOTE

You may be right there. I never thought of that but it is sitting on top of an older CRT type plastic encased TV. Good point.

 

[Nestor]

Actually, what the HK rep mentioned is correct advise. All things being equal, a 4ohm load will be louder than an 8ohm load. Again... that's all things being equal.

Since your centre speaker is of a different impedence to your mains, can I assume that they are of different make and model? If not, then I can only assume that the sensitivity of your centre channel speaker is much higher than your mains. That could be why the centre channel sounds more blended in with the mains when you lowered it. He/she did give the correct adivise given the circumstances. The only real way to see if it's good advice is to measure the decibles. But hey... whatever sounds good to you, right?

sleeper.

If you assume, that makes an "a$$" of "u" and "me"...

No it won't. It's not clear cut. For instance, my Chorus' are rated at 8ohms and 105db. My B&W's are rated at about 86db and 6ohms. Which plays louder?

Two speakers with "all things being equal" except impedance, will play the same volume. Only difference will be a higher current draw from the lower impedance.

HK should fire their rep.