Crossover Questions - Axiom Message Boards

I am confused by the cross-over issue. I understand the basic concept that the processor divides the audio signal and re-directs the low base signal to the sub, and sends only the higher frequency signals to the fronts, center and surrounds. So, the questions looms, if the lower base sounds are taken away from the front tower speakers, why do we even need tower speakers for fronts? What are the towers (80's or 60's, etc.) doing if the crossover is set at 60hz or 80hz?

I do listen to a lot of two channel stereo, so the towers could be useful there, but, couldn't a sub still be used to replace the towers even for stereo listening?

I want to buy the towers, but I am hoping that you guys can convince me that it is not a waste of money.

Bob,

Believe me, even with a crossover of 80hz, there is still a LOT OF KILLER base coming from your mains. 80hz is very low. Also, it does not just CUT OFF at 80, there is actually a gradual slope or blend during the transition.

The sub having a larger driver and built in amp will do a much better job with those lower frequencies than the small drivers on your center, surround, and mains. Yes the specs show the 60's and 80's go that low, however, they just can't move as much air as the larger sub driver.

This is why I recommend in your other thread a bigger sub for that huge space.

Besides, THX and others recommend 80hz for a crossover, which matches up with how the movie soundtracks are designed.

Bookshelves vs. towers.

Room size (volume) is the biggest factor. Bigger speakers fill bigger spaces.

It is mostly in your ears. I suggest an audition of both even if you order both and send one back.

BobG

My guess is that the M80's or M60's have all the bass below somewhere near 300hz going to the bass drivers.

A note on what sirquack said, that some bass below 80hz will go to the main speakers because the roll of is gradual... Although this may be true, I have heard that most digital crossovers to subs are very high order crossovers, which means very little bass at all below 80hz (or the selected crossover point) will actually go to the main speakers. This information may be available from the manufacturer of your receiver, but I have never seen it in a manual. You may have to ask if you really want to know, but I think it's a safe bet that it's a very high order crossover, hence, very little bass below the crossover point will go to the main speakers.

I have a strange issue where I think the answer is that my sub is too samll for my room and was hoping for some validation to this - My speakers when set to small and the crossover at 80hz give a nice bass response but when I set the speakers to large I hardly get any bass weather its music or movies.
I'm using a 225watt sub and was wondering if my 3600 cubic foot room with vaulted ceilings is too large for this size sub and is why I can't bass response when set to large.
Thank guys, -- Happy St. Patricks Day to you all

My other thought and I'm hoping I don't have to deal with this is that maybe my Onkyo 801 has the problem - where the large and small setting are backwards, and thats why I have this bass response problem

When setting the speakers to large, your receiver is probably disabling your subwoofer and sending the bass frequencies to the mains only.

When playing music, and with the receiver set to large, can you hear the sub if you put your ear next to it?

N24Color,

try giving these articles a read by the very knowledgeable Alan Lofft.

http://www.axiomaudio.com/deepbass.html
http://www.axiomaudio.com/bassmanagement.html

Richydog,

The sub is diffently working, I can hear it when set to large but like I said there is no comparision at all when its set to small.. when in large setting its like its waiting for a signal and when it gets one its volume and deep authority goes away - when in ht though it sounds wonderful - I'm puzzled and assuming at this point a larger sub might do it..

Ravi - thanks for the links - I haven't got the time to day but I will read that info and will let you know

N24Color,

If available, you may also want to consider switching the phase switch on your subwoofer and trying that. Please make sure your sub is OFF when you make the change.

Quote:

N24Color,

If available, you may also want to consider switching the phase switch on your subwoofer and trying that. Please make sure your sub is OFF when you make the change.

I've never shut either of my subs off when changing the phase switch. No problems as of yet. Am I tempting fate?

Quote:

I am confused by the cross-over issue. I understand the basic concept that the processor divides the audio signal and re-directs the low base signal to the sub, and sends only the higher frequency signals to the fronts, center and surrounds. So, the questions looms, if the lower base sounds are taken away from the front tower speakers, why do we even need tower speakers for fronts? What are the towers (80's or 60's, etc.) doing if the crossover is set at 60hz or 80hz?

I do listen to a lot of two channel stereo, so the towers could be useful there, but, couldn't a sub still be used to replace the towers even for stereo listening?

I want to buy the towers, but I am hoping that you guys can convince me that it is not a waste of money.

Great questions which depend very much on your listening habits. If you listened exclusively to HT I would suggest monitors plus subs would be optimal and save yourself the expense of full range speakers. If you listen to at least 50% music in stereo then full range floorstanders are a must, IMO.

When crossing the mains most receivers impose either a 12db or 24db /octave slope to the signal below the crossover point. While some LF sound finds its way to the mains not much is audible one octave below the crossover point , say at 40hz with a 80hz crossover.

For music listening, I've found using monitors with subs doesn't have the same sonic quality of a good full range loudspeaker owing to the greater dynamic range of the full range speaker and their superior built in crossover electronics and phasing. Also depending on your room acoustics and how good you are at blending the subs and mains, there are artifacts created around the crossover point which are more apparent with music than in HT.

So if you are using your system for both music and HT applications a full range main speaker would be a good choice. I have heard only one or two systems where a skilled calibrator was able to optimize monitors with stereo subwoofers that rivalled the dynamic range of floorstanders. For HT only applications, monitors with a capable sub(s)crossed at 80hz or higher, would likely suffice.