# Center Channel Port



## the_rookie (Sep 30, 2008)

So, my newest issue with my center channel isn't the placement atm, its the port.

So tonight, i was wanting to tweak and maximize my sub's input frequencies. So i First played some frequencies from my iPod to get a gauge of where the speakers started to roll off on the lower freq. My Towers played great down to 45Hz, very loud...sounded like a good diesel truck sitting in front of me. My book-shelves did fine down to 60hz or so. But my Center channel had intense port noise, and colored the sound way too much. When I would plug the port, the volume increase from it substantally. But still only lasted loud down to 60Hz.

So I currently have the xover on my sub set at 70Hz, cuz that's where I like the depth of my sub to hit, any higher makes the higher bass too loud for me. I don't like loud high bass. I love the deep stuff. So, I have my towers set to 50Hz, my Center set to 90Hz and the rears set to 80Hz. I would set my Center channel higher, like to 60Hz. But port noise is too much. 

So here are my questions.
1) If I have my towers set to 50Hz, does the sub only receive 50Hz and down?
2) If I blocked my center channel and brought the Hz down to 70 would that be good?
3) Is it just best to have all my speakers set to 70Hz xover than since my sub is set to there?


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## lalakersfan34 (Oct 31, 2007)

Hi,

I'm trying to understand exactly what you've done now, and I'm hoping you'll clarify things for me.



the_rookie said:


> So I currently have the xover on my sub set at 70Hz, cuz that's where I like the depth of my sub to hit, any higher makes the higher bass too loud for me. I don't like loud high bass. I love the deep stuff. So, I have my towers set to 50Hz, my Center set to 90Hz and the rears set to 80Hz. I would set my Center channel higher, like to 60Hz. But port noise is too much.


Let me know if I'm wrong, but it sounds like you're using multiple crossovers in your receiver:

fronts: 50hz
center: 90hz
surrounds: 80hz

BUT...you're using the subwoofer's built-in crossover knob as well and have that set to 70hz. Is this correct?

I'm curious why you're using the sub's built-in crossover. Usually when using a receiver with bass management (which your receiver has), it's advisable to either bypass the subwoofer's built-in crossover or, if it's not defeatable, turn the sub's crossover all the way up. The way you have things set right now, the subwoofer's crossover is interacting with the various crossovers you have set your other speakers to. This can sometimes cause unwanted effects. 

Have you tried bypassing the sub's crossover and seeing what you think of the sound? Since you've already been able to set your crossovers the way you want them for your speakers, I'd recommend getting the sub's crossover "out of the way" so to speak.

I look forward to your response. Good luck with everything!


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## the_rookie (Sep 30, 2008)

I have tried turning off the subs crossover.

But I have gotten ill effects from it, I still get higher freq from the AVR. My Onkyo 876 does have built in bass management, but I dont know exactly how the sub is handled. All I know is it does have a decent roll off for the freq. for the individual speakers so they dont get those freq, to maximize their own freq. handling. I am under the impression my AVR will automatically send my sub the LFE or Low end of the spectrum under any circumstance, the 180hz and down, but the bass mangement will limit what it sends to my speakers.


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## lalakersfan34 (Oct 31, 2007)

the_rookie said:


> I have tried turning off the subs crossover.
> 
> But I have gotten ill effects from it, I still get higher freq from the AVR. My Onkyo 876 does have built in bass management, but I dont know exactly how the sub is handled. All I know is it does have a decent roll off for the freq. for the individual speakers so they dont get those freq, to maximize their own freq. handling.


I'm not really sure what to make of this. You've tried turning off the subwoofer's crossover but have gotten "ill effects from it - you still get higher frequencies from the AVR." Could you try to clarify what you mean by this? It's not making a whole lot of sense, though I admit I could be missing something.



the_rookie said:


> I am under the impression my AVR will automatically send my sub the LFE or Low end of the spectrum under any circumstance, the 180hz and down, but the bass mangement will limit what it sends to my speakers.


You're speaking of different things here. "LFE" is its own discrete channel which brick walls at 120hz (no content above this) and is almost always covered solely by the subwoofer in a home theater setup. People often and mistakenly say "LFE" when they are talking about bass, but bass is present in the other channels of audio, too. As an example, CD's have bass and do not use an LFE channel. "LFE" and "low end of the spectrum" are two different things, and I'm a bit confused as to what problems you're running into.

Bass management dictates what part of a full-range signal from one of the other discrete channels (Front L/R, Center, Surrounds) are sent to the speakers and what is redirected to the subwoofer. This is what is referred to when discussing a crossover. For example, if a crossover of 80hz is employed for the front right channel in a system, the front right speaker is required to reproduce everything from 80hz and up, while the subwoofer receives the rest of the signal for this channel. From your post, it sounds like you're under the impression that a crossover limits how low your speaker will go, but it won't limit how high your subwoofer goes. This isn't the case. A crossover set at 80hz doesn't _only_ prevent the front right speaker from reproducing lower bass, it also rolls off the subwoofer's response above 80hz.

Let me know if I'm missing something obvious, and good luck


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## the_rookie (Sep 30, 2008)

So basically I will reiterate myself.

I tested each speakers crossover levels independently. So far this is my results;
Front (Left, Right): Had clean, loud bass up til 45hz.
Center: Had decent bass up til 89hz without port noise. When I plugged the Port it had bass up til around 60Hz.
Rears, I really didnt test because I just didnt feel like it.
Subwoofer, I had the crossover set to 70Hz, because when I tested it independently, It had too much boomy bass when I had the crossover any higher.

So respectively, when I did the Speaker Config on my Onkyo 876, I set the Fronts to 70Hz, the center channel to 90Hz, and my rears to 80Hz.

My original questions were;
1) If I have my towers set to 50Hz, does the sub only receive 50Hz and down?
2) If I blocked my center channel and brought the Hz down to 70 would that be good?
3) Is it just best to have all my speakers set to 70Hz xover than since my sub is set to there?


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## lalakersfan34 (Oct 31, 2007)

the_rookie said:


> My original questions were;
> 1) If I have my towers set to 50Hz, does the sub only receive 50Hz and down?


From the front L/R channels, yes. If other channels have higher crossover frequencies then the subwoofer will reproduce frequencies higher than 50hz from those other channels. Additionally, the subwoofer will receive signal higher than 50hz from the dedicated LFE channel. That said, using a 50hz crossover on the front channels means the front L/R speakers will go down to 50hz and the subwoofer will ONLY cover the frequencies below 50hz for these two channels.



the_rookie said:


> 2) If I blocked my center channel and brought the Hz down to 70 would that be good?


Possibly. Hate to say it, but experimentation is really the name of the game here. If blocking the port and setting the crossover for the center speaker to 70hz sounds better, that's what I'd do. Having not heard your system or the port noise you've experienced, it's hard for me to say what should or shouldn't be done. 

Out of curiosity, what is your center speaker? My center speaker is ported but I've never heard any port noise with a crossover of 80hz, even at high volumes. I find it odd that your center speaker is having such problems with port noise. My only guess (and it's really a stretch) is that if you're using Audyssey, maybe it's trying to boost frequencies right around or below the tuning point of your ported center speaker. I'd doubt it but I can't think of any reason for your center speaker to be having such a huge issue.



the_rookie said:


> 3) Is it just best to have all my speakers set to 70Hz xover than since my sub is set to there?


Again it's a matter of taste. Many receivers only allow for a universal crossover frequency and not independent crossover settings for each channel. My receiver is such a receiver, and as a result I have not experimented with using multiple crossovers in my system at the same time. Using a single crossover can simplify calibration and I'd recommend at least trying it out.

I really hate to have such open-ended answers but audio is very much about personal preferences and it is impossible to know what will sound best to you. There are general guidelines that tend to be a good starting place (trying a universal 80hz crossover for example), but rooms, gear, and preferences vary so greatly that each setup needs to be fine-tuned.

So to reiterate, I cannot say it is necessarily _best_ to set your crossover to 70hz for all speakers, but I do think you should try it and listen critically to your system with this setting. Hope you can figure out the settings you prefer for your system .


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## the_rookie (Sep 30, 2008)

Well I heard port noise when I played a dedicated frequency tone.

I had my AVR set to All Chn Stereo, unhooked my Fronts, and set my rears to none on the stereo, and played tones from my iPod, with the Equalizer set to None. I than played the tones, and would memorize at which frequency the speaker best handled the bass.

During my experimentation with my center, I noticed the port on the back had excessive "wind noise" and made the tone from the speaker inaudible. However, when I blocked the port, I noticed that the tone was audioible again, and sounding pretty good.

Down to around 60hz, after that the sound became inaudible.


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