Crossover Help

Posted by: hhiggins

Crossover Help - 04/23/19 01:01 PM

Hello Everyone,

New Axiom customer. Hopefully my speakers should be delivered within the next two weeks. I have ordered 9 speakers for my first "real" home theatre. They are as follows...

LCR - M5HPv4 In-wall
Rear - M2v4 In-wall
Atmos - M3v4 In-ceiling

I have been reading about speaker setup, specifically the crossover frequency as this is not something I have any knowledge of. Looking at the specs of the three speaker types they obviously have different frequency response capabilities.

What does the group recommend for crossover frequency for the above?

Thank you.
Posted by: Mojo

Re: Crossover Help - 04/23/19 01:10 PM

The cross-over frequency is not only speaker-dependent, it is also room/location-dependent. Presumably you have a receiver with auto set-up capabilities. The receiver will find the correct cross-over for each speaker. Using that as a baseline, you can then experiment with different settings. If you have a sub, setting the cross-over to a higher frequency will relieve your receiver of having to re-produce the majority of the lows which will give it some more headroom.

The flip-side of that is that the channel bass the recording engineer intended for that channel won't come through the intended speaker which may reduce the A/V experience. Since I got my QS10s for example, my receiver found them at 40Hz and I've left them there. I've been surprised how much bass content comes through and how great it sounds.

Great choice on the speakers BTW!
Posted by: hhiggins

Re: Crossover Help - 04/23/19 01:18 PM

Thanks Mojo! I have a Yamaha AVR RX-A3070 which uses YPAO. I will use that first and tweak as required as you suggested. I do have an old sub that I just couldn't afford to replace yet. Maybe next year.

I have also read that many of the auto set-up capabilities tend to set the front speakers to "large" and many people change that to "small". Is this something I should also keep an eye on during setup?
Posted by: Mojo

Re: Crossover Help - 04/23/19 01:24 PM

If you set them to large, the receiver will send the sub-bass to them as well. I don't recommend that with the M5s. As great as the M5s are, if you have your receiver's gain set anywhere near 0, the bass from the M5s will distort during peaks. Even if you had M100s I wouldn't do it because it will tax your Yammie.

So leave them as small. It is going to sound great and you'll be kicking yourself for not doing this earlier!
Posted by: hhiggins

Re: Crossover Help - 04/23/19 01:49 PM

Right on. Thanks for the info. I do have other questions on speaker placement as my room will present challenges. I will post those as a separate thread later.
Posted by: bman84

Re: Crossover Help - 04/23/19 04:07 PM

That'll be a nice setup! I thought I had my crossovers figured out until I ran Audyssey and realized that my room had a major impact on frequency response. For example, Axiom specs had me wanting to cross my M5s at 60hz, but my left channel M5 has a major dip in response at 70hz, so 80hz becomes the ideal crossover point.
Posted by: hhiggins

Re: Crossover Help - 04/30/19 10:55 AM

I'm sorry, but I am not sure how to interpret the graph you supplied. Can you point me to what to look at?
Posted by: Mojo

Re: Crossover Help - 04/30/19 11:59 AM

Look at the green trace on the left. Find the number 100 at the bottom of the chart. Now look at the large dip that goes down to -15. That's the dip in response bman is talking about. That's not because there's a problem with his M5. It's because he has a jog in his wall at a quarter wavelength of 70Hz away from his M5. It's causing destructive interference as a result, right at 70Hz, causing him to lose 15dB of signal at that frequency. 15dB is 32 times less power than he should have at that frequency.

The red chart on the left shows the correction his software on his Denon made. It's better but still down 9dB or about 16 times less power than he should have at that frequency.

Crossing over at 80Hz, as he said, allows his dual subs to take over which I imagine gets rid of that valley.
Posted by: hhiggins

Re: Crossover Help - 04/30/19 12:20 PM

Thank you very much! What would be required to make these types of graphs and to take these types of measurements?
Posted by: Mojo

Re: Crossover Help - 04/30/19 05:08 PM

You need a receiver like the Denon 4500H that bman has along with a $30 Audyssey app from the app store.

There are other ways too but they get more complicated.
Posted by: hhiggins

Re: Crossover Help - 05/01/19 08:41 AM

Thanks. I have a Yamaha RX-A3070 with YPAO. Not sure if that does what the Denon does. Will have to check that out.
Posted by: bman84

Re: Crossover Help - 05/01/19 08:57 AM

You'd need a receiver that uses Audyssey XT32 (Denon and Marantz mid-range units and above).

Just re-ran Aydyssey yesterday and got the following results, if you're interested:
Posted by: Mojo

Re: Crossover Help - 05/01/19 09:06 AM

The front left and front right correction is identical. I find that very surprising.
Posted by: bman84

Re: Crossover Help - 05/01/19 09:44 AM

Aside from the notch on my left-hand wall, the front of the room is symmetrical. I guess the notch doesn't make that big of a difference, and my previous result was wonky? It was windy outside that day, so the background noise may have skewed the results.
Posted by: Mojo

Re: Crossover Help - 05/01/19 10:02 AM

Understood but the pre-EQ curves are not identical and yet the post-EQ are. If the pre-EQ curves were identical, I could see how the post-EQ would end up being the same. It sounds better with Audyssey engaged, yes? I find with my Audyssey engaged, not only is the bass more defined, I can hear micro-dynamics that are completely veiled otherwise. These micro-dynamics make a huge difference in the definition of images and their relative location on the soundstage. v4 for sure has made a big difference compared to v2 but the room, even though I've pulled a few tricks, still sucks and blows. XT32 is another one of those fancy gimmicks that ought to be worshiped.