TC 80i midrange sounding muffled

marius94024

I just installed a home theater system in my home using TC 80i in-ceiling for the front three channels and TC60i for the rear channels.

The speakers mostly sound good, but the midrange seems a little muffled, even if I stand where they are pointed. This makes voices harder to hear.

Is there anything I can do do improve the situation? The back of the speakers basically point up into the attic, except I covered them with a small layer of weedblock fabric to keep the loose fill insulation from falling onto the back of the cone and getting stuck in the speaker.

My recevier is onkyo TX-605 if that makes a difference. All of the speakers have similar sound so I think we can rule out a speaker defect.

Thanks,

Mark

[Deleted User]

Hello Mark,
Thanks for posting on the Forum. Usually when someone describes the sound as "muffled" we suspect the operation of the tweeter. I know you said it was the mid range that was unclear, but I'm wondering if it is the high frequencies that are the cause? Some questions:
1). are any of these speakers within two feet of a wall?
2). is the sound "box-like"; seeming to be coming from inside a box? As opposed to sounding "open" and free of a boxy coloration.
3). what program material are you listening to? Does this problem change if you try another type of program material?
Regards, Ken

marius94024

> I know you said it was the mid range that was unclear, but I'm wondering if it is the high frequencies that are the cause?

Hmm, I think I heard high frequencies fairly well on my Art of Noise CD, but I'll have to check when I get home. I will confess to not being an "audiophile", so I have some trouble detecting exactly what is wrong.

1). are any of these speakers within two feet of a wall?

No, though they are within two feet of my projector screen. It sounds about the same with the screen up and down. I'll try to flip the >2' switch when I come home. I tried it before running auto-calibration on the receiver with no major effect, but I can try it again.

2). is the sound "box-like"; seeming to be coming from inside a box? As opposed to sounding "open" and free of a boxy coloration.

Yes, box-like seems like a reasonable way to describe it. Actually, it sounded really box-like until I ran the auto-calibration on my receiver. After that, the effect is fairly marginal.

3). what program material are you listening to? Does this problem change if you try another type of program material?

I noticed the problem with Van Halen and regular TV. I did not notice the problem when listening to classical music or Art of Noise, but I may not have been paying enough attention.

Since all speakers sound about the same, I suspect the problem is not a speaker defect, but is there any way I could have hooked them up wrong to create this problem? I think the only thing I had to do was hook up the speaker wire to the red and black terminals. Was anything else needed?

[Deleted User]

Hello,
Thanks for the additional information. In terms of electrical connections, the positive/negative speaker wire is all that's needed. There are some ways to avoid a box-like mid range coloration when dealing with in-ceiling or in-wall type speakers. It is important to absorb the rear sound wave the speaker produces. Some kind of sound absorbing material, such as Polyfil, can be placed into the cavity before installing the speakers. If the rear wave isn't dealt with it can reflect off of the interior surfaces of the cavity, then pass through the front surface of the speaker. This sound wave closely follows the main forward sound wave and adds a smearing quality to the sound. It can also add mid range coloration, a feeling that the music is coming from a box instead of from real instruments.
However, I believe in your case, the problem is related to the crossover between the sub-woofer (I'm assuming there's a sub-woofer as part of the system) and the TC80i speakers. It is possible the crossover frequency is too high, meaning there is an overlap between what the sub-woofer is playing and what the speakers are playing that is giving a cloudy quality to lower mid range/bass information. As a test, find a piece of music that makes the problem most noticeable and while it's playing turn down the sub-woofer. Granted there will be less bass information, but see if the mid range doesn't sound better.
Let us know what you find.
Ken

marius94024

I do not have a sub-woofer. (Have small kids, and using system mostly after bedtime, so decided the polk speakers would have enough bass for me... and they seem to).

I can certainly try the polyfil. Based on your description of how the reflecting soundwaves could be problematic, the problem could be related to the weedblock fabric I used to cover the speakers to keep the loose insulation away. It seems like it could be fairly reflective. I'll take that out and use polyfil instead.

This is the same polyfil that I can get in craft stores for stuffing pillows, etc, right? How thick of a layer do I need?

Thanks,

Mark

[Deleted User]

Hello,
Yes, that is the correct material. I would consider using a couple of double-handfulls of the stuff for each speaker. This should be sufficient.
Regards, Ken

hearingimpared

Welcome to Club Polk Mark.