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.

You're not running it in Direct mode, are you?

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.

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.

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.

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?

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.

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.

what spiff and ajax said.

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!

Glad to help. That's what we're here for.

mwc,

I'm fairly certain you are getting a big standing wave because of the room dimensions. It's very common. Try listening to the 63 Hz tone and moving around in the room with the sound level meter to measure the peak and null.

As to using a lower crossover at 80 Hz, apart from avoiding localization effects, there is a rationale that the smaller woofers in your main speakers will have better control for reproducing upper bass from 100 Hz up than the larger-diameter driver in a subwoofer. In other words, you may experience "tighter" bass by keeping the sub to frequencies of 80 Hz and below.

Regards,