Receiver crossover

[Hi Ho]

The lowest crossover setting on my receiver is 100hz. I'd rather have 80hz but I'll have to live with it until I get a new receiver.

Anyway, I was messing around with that "Bass I Love You" song (the best bass test ever!) about shaking my house off the foundation, when I noticed that my main speakers were moving like crazy. That's not right, is it? I don't think so.

I opened TrueRTA and play various test tones well below 100hz. When I got to 18hz, the mains started moving like crazy. They still get a signal below 100hz, and it doesn't seem to be rolled off much at all, if any. What is going on here? My receiver is a Panasonic SA-HE100.

Any ideas?

 

[jcPanny]

Are your mains set to LARGE?

If so, they will get the full range signal. Set to SMALL to engauge the crossover. Some receivers also have a setting for LFE = BOTH (mains and sub) vs. LFE = Sub only.

 

[Pyrrho]

There are two things to remember. The first is mentioned by jcPanny; the settings on your receiver likely allow you to have deep bass going to both the main speaker and the subwoofer. Make sure the receiver is set to "small" (or the equivalent word if Panasonic uses something else) for the main speakers (all of them, really), and if there is a subwoofer menu that gives three choices, "On", "Off", "Both" [sub and main], set it to "On", not "Both". You can consult your owners manual for details on this.

The second thing to remember is that a crossover point is where things start to be diminished. With a crossover setting of 100 Hz, it isn't normal for a receiver to send 99 Hz to the subwoofer only, and 101 Hz to the main speakers only. What it does is diminish the frequencies being sent to the other thing, so that 99 Hz is still going to the main speakers, only not as loud as it would without the crossover, and 98 Hz a little lower still, and 97 Hz even lower, etc. So, if you play test tones, you should be hearing things in your main speakers below 100 Hz.

 

[Hi Ho]

All of the speakers are set to small. The only options regarding the sub are "Yes" and "No". This is not a fancy receiver and it doesn't have any other options than that. There are no LFE options. I know about crossover points, slope, and roll-off. I even tried setting the crossover to 200hz (the only other setting) and nothing changed. I know there will still be sound from the mains below 100hz but isn't 18hz A bit too low? Shouldn't it be rolled off enough by 18hz so that it does not affect the speakers? Another thing is, the amps in the receiver have a rated frequency response of 40hz-20khz. I know that's not set in stone but I wouldn't think it would even be capable of 18hz. Maybe I should be picking up a Yamaha 2500 even sooner than I was planning?

 

[MDS]

The slope of the xover affects how rapidly the frequencies below the xover point are attenuated. The typical 24 dB/Octave xover will cut the frequencies at 50 Hz by 24 dB, but how high in amplitude was the signal to begin with? Being a bass test CD I would assume very loud and there will still be sufficient amplitude to move the driver at even very low frequencies.

When a speaker is rated to 40 Hz, that is the point at which the response drops off by 3 dB. It will still try to play well below that but the response will be diminished even more.

 

[Hi Ho]

HERE is a video. Maybe it's some sort of anomaly? It's the very lowest notes, where the woofer moves very slowly, which I am curious about. When I play an 18hz tone, I get the same thing from the mains. I just don't want to damage my recently completed DIY speakers.