Audyssey Speaker Large/Small & Crossover Setting??

[408Revo]

Hi everyone, I'm new to this so please bear with me if the answer is obvious. I know this topic has been discussed all over the net but I can't find the information I'm looking for.
I'm trying to understand exactly what these setting do to a speaker. I did some tests on REW to try to understand but now it seems that I'm completely confused.

I ran a sweep [20-200] on my main left speaker with the following:
Speaker set to Large with xover set to 100 and 40
Speaker set to Small with xover set to 100 and 40

I then did the exact same sweeps but with Audyssey Off [multeq xt32 off]

1. In every scenario there were frequencies below each xover setting. Why am I getting frequencies below these xover settings?
2. I didn't see much of a difference when speaker was selected large or small. I thought for sure if I had the speaker set to small, no low frequencies would make it to the speaker.
3. I did notice that with Audyssey on, I got a much flatter curve. That was the only difference I saw.

Maybe I'm doing something wrong when testing?
I decided to do this when I set my front speakers to Large after running Audyssey for the first time on my "new" x4500. My previous receiver was a x4000 and was able to tell a difference between small and large. Any help is greatly appreciated. thanks

 

[Wayne A. Pflughaupt]

1. In every scenario there were frequencies below each xover setting. Why am I getting frequencies below these xover settings?

That’s normal. The sound doesn’t just disappear into a black hole when it gets down to the crossover frequency. It’s a filter that rolls out frequency response at xx dB per octave below the frequency setting. 24 dB/octave is a common filter slope. To put it crudely, if you have the crossover on the main speakers set for 100 Hz and that frequency is generating 85 dB sound level, than one octave below that, 50 Hz, will generate a signal at 61 dB (i.e. 24 dB lower). (Octaves halve the starting frequency when you’re going down, and double when you’re going up.)

Here's a graph showing the frequency response applied to a signal with a variety of slopes.

2. I didn't see much of a difference when speaker was selected large or small. I thought for sure if I had the speaker set to small, no low frequencies would make it to the speaker.

As noted, the filtering is not a brick wall. Aside from that, your particular speaker will make a difference on the large vs. small setting. If you have large floor-standing speakers with powerful woofers, then you should hear (and measure) a difference. If you have speakers with little 5-1/4” woofers, they aren’t putting out much bass to start with, so you won’t see much of a difference.

3. I did notice that with Audyssey on, I got a much flatter curve. That was the only difference I saw.

Yes. Smoothing out the response curve is what Audyssey is for.

Regards,
Wayne

 

[408Revo]

Thank you Wayne, appreciate your response. For some reason I thought it was a complete cut off. From the little I know when a speaker is set to small, all LFE gets routed to the sub regardless of the xover setting?
When set to large, only the frequencies below xover get routed to the sub?

What's the benefit of setting your mains to large if you are not really able to get any bass from them? I have some old Cerwin Vega towers with 15s in them and I am able get some decent bass when hook up to a 2 channel receiver.

When I upgraded my receiver to the x4500, I was going in circles trying to figure out why there was absolutely no bass coming out my towers. They just sounded like some book shelf speakers to be honest. I ended up getting the multeq-x app and applied a 2nd order low shelf gain at 100htz with a gain of 10dBs and finally was able to hear some sound from the old Vega's.

I still have to do more research to fully understand the graph you provided and how it relates to the graph below. This is the one that compares my front L main when set to large or small. This was taken with the SPL meter set at 75dB prior to doing the sweeps.

 

[Dr.OP]

Do you have subwoofer on or off?

 

[408Revo]

That was the problem, subs were on. Had no idea that a signal was being sent to the subs as well.