Axiom Home Page Forums General Discussion Technical Questions One more question regarding crossover frequency

Hi all,
I have a pretty good understanding of this principle but am lacking in one area. It's not yet clear to me...if say...I set my Denon - 4802R crossover to 80 Hz...and my mains to large....if I will get any overlap. What I mean is...I don't want all freqs under 80 Hz to go only to the sub....nor do I want all freqs just above 80 Hz to go only to the mains. What I really want is...a nice gradual blend... The sub to handle what the mains absolutely can't...(in this case we're talking M80s for those who haven't read my other posts)....but I also want the sub adding punch to those frequencies that the mains can handle. It's not clear from the Denon manual if the crossover pt is a sharp cutoff. What's the best approach here...or am I asking for something that I shouldn't be?

If you set your crossover at 80Hz and your mains to "small," there IS a gradual blending. It's not like everything above 80Hz goes to the mains, and everything below goes to the sub. There is a roll off of the volume of frequencies lower than 80Hz being sent to the mains BEGINNING at 80Hz. How quickly the volume tapers off is called the slope. It can drop off at 6dB per octave, or 12 dB per octave, etc.

Anyway the point is, there ARE frequencies below 80Hz coming from your mains, and frequencies above 80Hz, coming from your sub. It's just that at frequencies below 80Hz, there is a gradual drop off in volume in the mains, and a drop off in volume of frequencies above 80Hz coming from the sub.

Can someone with a little technical expertise say this better please? I'm driving myself nuts!

OH...I thought 80 Hz...would be basically the 3db pt...and while yes...frequencies still pass, they're just attenuated such that they have little affect?? I guess I'm just trying to make sure that I get good bass to the M80's and to the sub -- have I mentioned that it's due to arrive today!!!

Well, they ARE attenuated, but they DO have effect. If I understand correctly, we humans don't hear a change in volume until it changes +/- DB. And then, the difference is barely noticeable. So even if the volume is down DB and more, it is still audible. Hope I've got that right.

Eight, the way to get the nice gradual blend that you want is to set all speakers(including the M80s)"small", to set the crossover in the 4802 to 80Hz and to have lows set to subwoofer only. The receiver then rolls off the speakers below 80Hz at typically 12dB per octave and rolls off the sub at 24dB per octave above 80Hz.

Thanks Ajax and John. I guess the next question is...is this what I want...or would I be better served leaving my fronts large and crossover at 80. After spending an hour at UPS this evening I finally came back with the 82 lbs that is my new SVS sub. Of course I hooked it up...while my wife was watching the Bachelor...and proceeded to regale her with overwhelming bass. I have some serious tweaking to do. Currently...I left the setting at large...crossover at 80...and there's another setting on the Denon...under the sub menu...where you can have Large + sub... or THX...for now I have it at large + sub.

A downside to the Denon (and the only one I've seen thus far) is that you HAVE to use the onscreen display for any meaningful tweaking. This would have meant my wife would have missed the revealing of the mole...on the Bachelor...and you can guess how that would have gone over. (ok everyone...quit pretending you don't know what I'm talking about )

JohnK said it above. All speakers to "small" crossover at 80Hz. I can't address the other Denon settings. I have an Onkyo.

Eight(nka Malcolm), if you set all speakers "small" as Denon generally recommends, the additional sub setting you mention doesn't appear, and all frequencies below 80Hz(subject to the rolloff described)are automatically sent to the sub alone. If the mains are set "large", that sub setting appears. Large + sub has both mains and sub playing all the very low frequency material simultaneously, THX would have only the mains playing the low frequencies of the main channel. Again, this has no application when all speakers are set "small".

Thanks all. I think I'll experiment with both to determine which I prefer.... I'm looking forward to watching my first movie on these speakers this weekend.

eightman, I have a Denon 2802 and M60s, etc... I leave the M60s set to large, crossover at 80hz, w/ "LFE + main" selected. I tried them set to small but didn't like that configuration for music. Rather than have to go into the on-screen setup menu every time I wanted to listen to music, I leave them set to large all the time. Sounds better (to me) for movies anyway.