Whats the deal with the center channel? - AVS Forum
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post #1 of 15 Old 05-18-2009, 10:52 AM - Thread Starter
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Ive bought 3 different receivers in the past few months because i havnt decided on what i like yet. So far 2 of them had blown center channels. I got one off e-bay and one at a swap n shop so i knew i was taking a risk but i dont understand whats happening?

Are people using junk center channels? are they blowing them, wrong impedance or what? 2 out of 3 blown seems like really weird odds.

One was an Harmon/Kardon AVR35, the other is a Denon AVR-87 both older units i know but my point is are the center channels really fragile? do i need to keep an eye on mine? Ive taken the grill off mine now and im keeping on eye on how much its moving because i guess it can be deceiving on how hard they are being driven?

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post #2 of 15 Old 05-18-2009, 11:04 AM
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Maybe try buying one from a reputable place and you likely wont have this issue. I have never heard of this being an issue.
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post #3 of 15 Old 05-18-2009, 11:17 AM
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No, the center channel is no more fragile than any of the other channels. Those are prehistoric models compared to todays standards so unless you know and trust the seller any purchase is going to be a crap shoot. How much the speaker is moving is of no relevance either.
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post #4 of 15 Old 05-18-2009, 01:38 PM
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One possible cause of a blown channel would be blown power transistor. That could happen from overheating.

The center channel could be running at a higher average output level, I have seen this in some movies. Or people could be bumping the center level up a lot to hear it.

In my opinion though, much more likely is coincidence.

The odds of getting four of a kind again after getting it in the previous hand is no lower. And while the odds of someone getting a royal flush is very low that does not mean it happens. Just because I am terrible at golf, does not mean I will never get a hole in one ( in fact, I got one last year.)

"But this one goes up to 11"
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post #5 of 15 Old 05-18-2009, 08:38 PM - Thread Starter
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I do that though with the 2 receivers i have that work. I crank my center channel and then use the volume and the levels to bring the front and rear up to match it how i like.

They are old receivers i know but i got them cheap so thats why i got them. All my stuff is just cheap junk though so i couldnt see spending $1k on a receiver.

How do you guys set your center channel? Do you do it like i do or differently?

I havnt blown any center channels but im wondering if i may be doing somthing wrong and i dont want to.

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How can you tell a point is a reflection point?
Quote:
Originally Posted by maxcooper
sit in normal spot
have friend slide mirror on wall
see speaker? bingo!-Max
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post #6 of 15 Old 05-19-2009, 06:03 AM
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Quote:
Originally Posted by BowerR64 View Post

I do that though with the 2 receivers i have that work. I crank my center channel and then use the volume and the levels to bring the front and rear up to match it how i like.

How do you crank the center? Just turning up that channel in the speaker setup menu is pointless.

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How do you guys set your center channel? Do you do it like i do or differently?

Adjust all channels equal at 75dB using pink noise or pulses.

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post #7 of 15 Old 05-19-2009, 07:30 AM
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You don't mention your speakers, which could be part of the problem. It is possible they are unusually low in impedance and sensitivity, which may putting too much demand on the aged receivers, or because the speaker connection is faulty and causing the receiver's to short and/or suffer damage.

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post #8 of 15 Old 05-19-2009, 08:34 AM - Thread Starter
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Quote:
Originally Posted by Kal Rubinson View Post

How do you crank the center? Just turning up that channel in the speaker setup menu is pointless.

Adjust all channels equal at 75dB using pink noise or pulses.


Well the receivers have a level setting for each channel, you can select the speaker size and the DB level for each independant of the master volume.

I have been adjusting my center to the max first then adjust the surround to a leverl that sounds balanced to my ear. Im not having issues with blowing them but i wonder after receiving 2 top brands with blown center channels if i should do more research on this channel because i may have the same problems.

The HK receiver i had fixed and it works and sounds great but if has blown before i might want to be careful on how i use it.

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Originally Posted by dsmith901 View Post

You don't mention your speakers, which could be part of the problem. It is possible they are unusually low in impedance and sensitivity, which may putting too much demand on the aged receivers, or because the speaker connection is faulty and causing the receiver's to short and/or suffer damage.


Well i didnt list mine because i havnt had an issue with them on my system. It just seems odd that a brand like Denon and HK both had center channel issues. Older cheap Aiwa i have didnt have a blown center nor did an older 90s Sony receiver i sold a friend.

Maybe it is a coincidence.

The Denon has a pre center out and i hooked a seperate amp to the pre output and it works so the problem is in the output stage of the amp.

Quote:
Originally Posted by donsantos
How can you tell a point is a reflection point?
Quote:
Originally Posted by maxcooper
sit in normal spot
have friend slide mirror on wall
see speaker? bingo!-Max
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post #9 of 15 Old 05-19-2009, 08:55 AM
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Quote:
Originally Posted by BowerR64 View Post

I have been adjusting my center to the max first then adjust the surround to a leverl that sounds balanced to my ear. Im not having issues with blowing them but i wonder after receiving 2 top brands with blown center channels if i should do more research on this channel because i may have the same problems.

Makes no sense, of course. These are trim settings and maxing any one, a priori, creates potential problems with setting the others.

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post #10 of 15 Old 05-19-2009, 09:15 AM
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I don't know why you would set your center level to maximum. Follow Kal's advice, and set all your channels to hit some pre determined level such as 75 dB using an SPL meter or use auto setup if available.

"But this one goes up to 11"
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post #11 of 15 Old 05-19-2009, 12:13 PM - Thread Starter
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Well im still new so im not sure what im trying to say.

There is a master volume on the receiver, its a big round knob. Then each speaker has its own independant volume or level.

I find the place where i normaly watch tv (im in a wheelchair so i dont have a fixed seating position) i may have left out the fact im in a chair.

Now once i adjust the center i then adjust the front and rear to sort of match or balance out what sounds right to my ear.

I dont know why i start with the center, maybe because it has more midrange or the majority of what i watch has more dialog or what im not sure it just seems to be what i do. It seems to sound ok


Mabe i should just shutup and leave it, its just fun to talk about i guess. Im hoping for more info as i want to learn more

Quote:
Originally Posted by donsantos
How can you tell a point is a reflection point?
Quote:
Originally Posted by maxcooper
sit in normal spot
have friend slide mirror on wall
see speaker? bingo!-Max
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post #12 of 15 Old 05-19-2009, 01:47 PM
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The channel trims are used to balance out the system. Using test tones, you want each speaker to play back the same average SPL level at your listening position.

What Kal is suggesting, is that you set each channel trim such that the speaker outputs 75 dB at a set volume level, probably 0 dB. That seems to be how Yamaha's YPAO sets my speakers, as they all play at roughly 75 dB with a volume of 0. They play louder with real world material, as the test tones are intentionally designed to be quieter for user comfort. In my case, 0 dB is very loud, over 90 dB SPL at my listening position.

"But this one goes up to 11"
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post #13 of 15 Old 05-19-2009, 02:23 PM
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BowerR64,

If your receiver is too old to include auto-calibration (with a special mic), go buy a SPL meter (cheap at Radio Shack) and a calibration disc with test tones like Kal mentioned. Set your master volume to 0 db or whatever reference vol level you want. Then do what MJ suggested above. This is how you supposed to setup your receivers.
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post #14 of 15 Old 05-19-2009, 02:37 PM
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Quote:
Originally Posted by Foxbat121 View Post

BowerR64,

If your receiver is too old to include auto-calibration (with a special mic), go buy a SPL meter (cheap at Radio Shack) and a calibration disc with test tones like Kal mentioned. Set your master volume to 0 db or whatever reference vol level you want. Then do what MJ suggested above. This is how you supposed to setup your receivers.

A lot of receivers have internal test tones, so you may not need a disc.

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post #15 of 15 Old 05-19-2009, 02:41 PM
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[quote=Foxbat121;16492049]BowerR64,

If your receiver is too old to include auto-calibration (with a special mic), go buy a SPL meter (cheap at Radio Shack)

Cheaper still at Aperion, a speaker mfg. who happens to sell a decent spl meter for 29.95, if I remember right. If it's cheaper and does the same job, it's for me!
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