Axiom Home Page Forums General Discussion Home Theater Advanced crossover settings

I'm thinking of upgrading my M22's with some M80s. Right now I have my M22s crossed over at 60 hz and the rest of my speakers at 80hz. (I'm using a Denon 3808). With the M80s I could cross-over at 40hz or lower. My question is that I've read (I think in users manuals or somewhere) that when setting your main's crossover lower than the rest of the speakers you can have a gap in bass frequencies. Is that true? And if it is, that's stupid.

The crossover setting for each speaker is the point where you direct the low frequencies to the sub. If you have all speakers set to small, which you should, and say have the 80's on 40hz, anything below that will go to the sub. With that said, you should turn all speakers to small. Most speakers should be set to 80hz or higher. The 80's can go down to 40hz, but your better off using 60 or 80, as the sub will do a better job in those low frequencies.

This is also Audyssey's recommendations, and the creator of THX helped create Audyssey.

It is possible, regardless of where you set your crossover, that you will have 'holes'. It all depends on how low frequency sound interacts with your room.

The advantage of directing the low stuff to your sub is that you have more flexibility in placement with the sub. There is a limited area where you can place your mains for them to form a proper soundstage at higher frequencies.

Its probably a good idea to experiment to see what sounds best in your room. There is at least one person on this board that has posted that they get better bass with both the mains and the sub producing the low stuff.

Then what's the real advantage of having floor standing speakers that can go low when you're crossing over at 80hz? And if I was crossing over at 80hz would I really be able to tell a difference between the 80's and the 22's? I know there's a separate stereo/direct crossover I can use, so perhaps for music listening I could take more advantage of the 80's bass capabilities. One final question, why do receivers have separate crossover settings for speakers if it can lead to gaps in bass response (i.e. crossing over the mains at 40, the rest at 80hz leads to it essentially setting the crossover at 40hz, which leaves a gap for all the other speakers if they cannot go down to 40).

They don't just "cut off" there is a roll off or "slope". Do you understand how low 80hz really is? The reason each speaker can be set with different crossovers is because different speakers have different frequency response. You don't want to send them a lower frequency than they can handle efficiently. If you study the +/- 3dB point for each speaker you will see that they are different.

Google is your friend.

It does not lead to gaps, not sure why you would think that way.

I must admit I am also one of those that has experimented with a number of AVR's and found the "both" setting for the mains and sub give me the best overall sound for my particular environment. I would add, however, that this setting has worked better with full-range floor-standing speakers then bookshelf models. I have tried both. I originally used M22's as mains, however, in this setting they just seemed to strain a little more in the mid/low bass region particularly at higher volumes. I replaced them with M60's which cured that issue beautifully. You might have to check and raise your sub volume 2-3 db as opposed to the 80hz crossover for all speaker settings since it drains some of the bass energy from the subs. All my other speakers are set to 80hz. I have tried many permutations and combinations of this and I always seem to come back to the "both" bass management set-up. It has always seemed to sound the best to me and dealt better with any "holes" problems in the overall soundstage that might exist.

Yeah I know about rolling off frequencies. I'm just saying what I read somewhere in my history of researching receivers, was that using separate x over settings resulted in the bass from the higher x-over speakers not being redirected to the sub. It said you shouldn't have too much of a difference between your highest and lowest x-overs. This statement has confused me, as it seems to defeat the purpose of having separate cross overs (i.e running almost full range mains while having surrounds x-ed over much higher). Hopefully what i read was wrong and is complete b.s. and was based on poorly translating Japanese or reading a Denon manual.

Crossover setting aside I’m curious why you are considering changing from your M22s to M80s?

As for the Dolby and THX recommendations take them as such…recommendations. They are designed to create a standard between recording and playback so that you ostensibly hear what the sound engineer intended. They also provides a simple way to setup a system for the majority of people who don’t want to spend the time and effort tweaking their systems to find exactly what they prefer. So if you want to try, or find you prefer, a lower/higher crossover or different speaker placement than recommended then by all means do it.

I found that in my apartment setup running the M80s large and the subwoofer LFE+Mains substantially evened out the bass and also gave more of a feeling of impact to the M80s which I sat fairly close to. However, in the larger room I’m now in I’m not seeing the same benefits and may even be noticing some power related advantages to running the M80s small.

Back to what the real question seems to be…what is it you are looking for in moving from the M22s to the M80s?

Cheers,
Dean

Mario, you may have misinterpreted what you read, or it may simply have been wrong. Most modern HT receivers allow setting different crossover frequencies for different speaker groups, and the lowest frequency set doesn't overrule the other settings, which would make no sense.

So, don't worry about that happening, but also don't worry about setting one or more of your speakers at a frequency higher than their maximum extension. The entire idea of bass management with a good sub is to allow it to handle the very low frequencies which it does best while allowing the speakers to handle the frequencies which they do best a little more cleanly. A large speaker such as the M80, set "small" and crossed over at maybe 80Hz will still be able to play the higher frequencies at a louder level with lower distortion than a smaller speaker would.

Okay, reading the article that you linked, it appears that part of the discussion is at least outdated. Most(all?)modern HT receivers don't roll off the bass in the sub from all the speakers set "small" above the lowest frequency set for any of them. The LFE channel is also not rolled off above that lowest frequency. His concluding summary remains as mostly good advice.

Here's a link giving an example of what I'm describing. http://www.hometheaterhifi.com/volume_9_3/feature-article-multiple-crossovers-9-2002.html
Start reading about 3/4 the way down, starting with the topic line: Mixing high and low frequency crossovers in a multi-channel set up.

So I guess if I were to get the M80's I should cross them over at 80hz for home theater use, maybe lower for 2 channel/direct mode (provided I get acceptable bass response). I do have a Radio Shack SPL meter and Digital Video Essentials for calibrating, by the way.

I guess what this boils down to is would upgrading to M80's be a significant improvement over M22's?