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#74419 - 01/03/05 10:35 AM S.O.S-either me or my Denon 3805 has gone cookoo
mwc Offline
aficionado

Registered: 07/21/02
Posts: 958
Loc: Texas(DFW)..that country to th...
I have my Denon AVR-3805 setup this way:
1. All speakers set to small, subwoofer-yes
2. Crossover at 120
3. EQ off
4. sub crossover control set to off (so that the receiver handles the crossover.)

Here is the problem:
I get a huge peak (10db+) at 63Hz according to the RS meter and the Rives Audio Test CD 2 (tones are corrected values for RS meter).

But get this, the peak at 63Hz is coming from the mains. Shouldn't there be little or nothing in the 63Hz range coming from the mains with the crossover set to 120 and mains set to small? This happens even if I run the tone and turn the volume control all the way down on the sub. Could there be something wrong with my receiver? This just started happening yesterday-everything was fine last week when I ran the same test.

Any thoughts/comments/solutions appreciated.

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#74420 - 01/03/05 05:41 PM Re: S.O.S-either me or my Denon 3805 has gone cook
pmbuko Offline
shareholder in the making

Registered: 04/02/03
Posts: 16437
Loc: Ben Lomond, California
You're not running it in Direct mode, are you?
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#74421 - 01/03/05 06:29 PM Re: S.O.S-either me or my Denon 3805 has gone cook
Ray3 Offline
connoisseur

Registered: 02/02/04
Posts: 2854
Loc: Rochester, NY
Get the manual out and check the settings. Something is not set correctly. I'd start with the crossover at 80 to see if that helps.

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#74422 - 01/03/05 06:43 PM Re: S.O.S-either me or my Denon 3805 has gone cook
spiffnme Offline
axiomite

Registered: 04/01/03
Posts: 5233
Loc: Los Angeles
Just curious why you'd set the cross-over so high. Most people set theirs at 80hz or lower. Personally I have mine set at 80hz for movies/tv and 60hz for music.

Not sure why that would have any effect on the results your finding, but it's certainly something I'd change.

Are your mains in a corner, or very near a side wall? That'll create havok with your readings as well.


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#74423 - 01/03/05 09:35 PM Re: S.O.S-either me or my Denon 3805 has gone cookoo
mwc Offline
aficionado

Registered: 07/21/02
Posts: 958
Loc: Texas(DFW)..that country to th...
Thanks for the suggestions guys but I've solved the problem. It was caused by a null at the listening position at 1Kh which is the reference tone. I recently added some diy room treatments that caused the null which wasn't there before.

I took a reading at 1Kh and another at 4Kh and then used the difference between the two and it worked out fine with a little speaker repositioning. But I'm still puzzled by the mains putting out that much output at 63Hz when the crossover is at 120Hz when there is supposed to be at least a 12db drop between crossover settings.

Craig: I set my crossover at 120 because that is where I get the most even response from 20hz-200Hz and I have my sub positioned between the mains. Localization has not been a problem. But I think the bigger question is:

If the sub is positioned in such a way that there is no danger of localization (as mine is), why not have a higher crossover point.

I mean, we have subs such as the HSU,SVS,etc. that are highly capable of producing high quality clean bass above the widely accepted 80Hz point. Do we all use 80Hz just because THX says so.? Did we all buy expensive subs just to supplement our "full range" speakers with the bottom octave?

I think a higher crossover for the sub allows greater flexibility in speaker placement and takes more of the burden off the amp and main speakers which could result in less distortion and compression.

If a sub is crappy enough to sound poor at any crossover point, then yes let the mains handle as much of the bass as they can.

I have yet to hear a good reason (other than localization or if the mains produce higher quality bass) for not using a higher crossover point than 80. Here is a terrific article that touches on this subject.

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#74424 - 01/03/05 10:29 PM Re: S.O.S-either me or my Denon 3805 has gone cookoo
donjuanmiguel Offline
veteran

Registered: 12/03/04
Posts: 132
Hi. I'm fairly new here so be patient with the question. You say you have the sub cross set to off? Won't this prevent very little signal coming from your receiver no matter what the crossover setting is there?
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#74425 - 01/03/05 10:56 PM Re: S.O.S-either me or my Denon 3805 has gone cookoo
spiffnme Offline
axiomite

Registered: 04/01/03
Posts: 5233
Loc: Los Angeles
quite the opposite. With the cross-over on the sub turned off, it'll receive the entire signal that the receiver sends it, as the cross-over job is being handled by the receiver.




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"A nation cannot prosper long, when it favors only the prosperous." -President Barack Obama

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#74426 - 01/03/05 11:00 PM Re: S.O.S-either me or my Denon 3805 has gone cookoo
Ajax Offline
axiomite

Registered: 12/30/03
Posts: 6331
Loc: Cleveland, Ohio
John, there are two ways to hookup and run a powered sub.

1. You can run speaker cables from the speaker outputs of the receiver to the sub's speaker inputs, and then run speaker cables from the sub's speaker outputs to your speakers. When hooked up this way, the crossover in the sub is active and does the separating of the signal.

2. Run a single subwoofer cable (RCA connectors at both ends of the cable) from the receiver's "sub out" jack to the "sub in" jack on the sub. Hooked up this way, the crossover in the receiver does the separating of the signal, and you should be sure the sub's crossover is turned to off and/or turned up to it's highest setting so as not to interfere with the receiver's crossover.
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#74427 - 01/04/05 12:04 AM Re: S.O.S-either me or my Denon 3805 has gone cookoo
mwc Offline
aficionado

Registered: 07/21/02
Posts: 958
Loc: Texas(DFW)..that country to th...
what spiff and ajax said.
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#74428 - 01/04/05 12:42 PM Re: S.O.S-either me or my Denon 3805 has gone cookoo
donjuanmiguel Offline
veteran

Registered: 12/03/04
Posts: 132
Hey, thanks for that info. It makes sense now. I was under the impression turning the dial on the sub was like turningn a volume control. All this stuff is really cool to learn. Thanks!
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