Sierras, Dynaudio, REW, and my room

Hey guys, a few weeks ago I got hold of a Dynaudio Audience 42C center channel and I did some listening comparison with my Sierras. My receiver is an Onkyo 805.

Here's a pic of the Dynaudio:

http://www.dynaudiousa.com/products/...oldaud/42C.jpg

And of course the Sierra:

http://img137.imageshack.us/img137/1...cpbngmrzo3.jpg

I noticed the Dynaudio seemed a little more prominent in the lower midrange (say around 100-200hz) maybe that's upper bass, I'm not sure. Anyways it prompted me to take same measurements to see if my Sierra was lacking in this range or if the Dynaudio was boosted.

Using REW on my PC and an AKG Perception 150 microphone (with calibration file loaded) here's what I came up with for each speaker measured from 6 inches away. Both speakers were mounted vertically on a speaker stand.

Sierra:
http://img204.imageshack.us/img204/7...noeq6inct6.jpg

Dynaudio:
http://img372.imageshack.us/img372/7...ence42cmv5.jpg

Overlay:
http://img150.imageshack.us/img150/5...overlayab2.jpg

You can ignore below 80hz because I was running the speakers as small with an 80hz crossover from my receiver.

It looks like the Dynaudio has a boost of around 3-4dB in the 100-200hz range. The Sierra is flatter in this range and certainly isn't lacking. Also interesting is that the treble range on the Dynaudio seems to be a bit higher than the Sierras well.

Now here's where things start getting interesting. I decided to measure from my couch where I normally sit. This is about 8 feet away from the speakers.

Sierra:
http://img150.imageshack.us/img150/2...uchnoeqwg0.jpg

Dynaudio:
http://img98.imageshack.us/img98/263...uchnoeqze4.jpg

The top line in each graph is the measurement from 6 inches. The bottom is from 8 feet.

As you can see in both graphs, my room is causing a suckout in the 100-300hz range. This explains why I have felt the Sierras sound a little "thin" in my room. I've often used the manual EQ in my receiver to try and boost this range as well as reduce the mid-bass around 45-60hz. But I could never get it quite right.

I've tried the Audyssey calibration on my receiver but didn't like how it reduced the high frequencies so much. But then I read how you can just use the treble adjustment to boost it back up a little. Knowing that, I decided to run Audyssey again. Here's what it did:

Sierra with and without Audyssey:
http://img98.imageshack.us/img98/637...udysseyoc2.jpg

Zoomed in a little:
http://img214.imageshack.us/img214/6...dysseyzai3.jpg

The gold line is Audyssey. As you can see, Audyssey added around 3-5dB from 100hz to 250hz. It also reduced the treble quite a bit. This gave the Sierras a fuller sound but muted treble. I used the treble adjustment on my receiver by +2dB and it sounded much better. So it looks like Audyssey did a decent job with the lower midrange suckout. Although I don't know why it had to mess around with treble. It's actually flatter without Audyssey.

I also took measurements of the sub (JL Fathom F112), and Audyssey did a very good job with that. Measured from the couch about 8 feet away.

http://img161.imageshack.us/img161/1...udysseydj5.jpg

Audyssey (blue line) flattened out the sub's response considerable. Much easier than messing with the Behringer EQ.

Here's a before and after pic of the entire frequency range. Note - This doesn't show the treble increase I added back in with the tone controls.

Before:
http://img214.imageshack.us/img214/3195/009noeqxm6.jpg

After:
http://img214.imageshack.us/img214/4...udysseypc0.jpg

Overall I'm pretty happy with the results. Vocals sound fuller now without being artificial. And the midbass is not as prominent as it was before. I'll probably be sticking with this configuration for a while. I might be moving soon so I may have to do this all over again. :(

One thing that is important to remember I think, is that Audyssey isn't really fixing the problem. It's merely masking it. I'm not sure if putting up room treatments would fix the problem. It could be the room dimensions which I can't do anything about. Anyhow, I had fun taking the measurements and I think I learned a few things. One of which, is don't judge a speakers sound without knowing how the room is affecting them.

Great stuff Mike!

One comment, that 100-300Hz suckout might not be your room at all. This is common with floor (or ceiling) bounce, first reflections etc. Close mic measurements won't reveal much of this.

Try raising or lowering the speaker 1 foot and then compare the measurements. You might even try throwing a pile of pillows on the floor at the midpoint betwen the speaker and mic and see if it reduces the suckout.

I also do not like how Audyssey forces that HF rolloff. It should EQ to as close to flat as possible. Regrettably, it does not. It is my understanding that the high frequency roll off caused by Audyssey is by design.

Quote:

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One thing that is important to remember I think, is that Audyssey isn't really fixing the problem. It's merely masking it.

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This is correct, Audyssey or any form of room EQ does not actually fix the problem. It attempts to compensate by increasing or decreasing amplitude at the problematic frequency range based on your listening position. If you have a problematic room with bad room modes, it could actually make things worse for people seated at different positions.

Thanks Dave! I'm going to give that a try. I think that if you do the pro-calibration on some Denon receivers, they have an option for Audyssey Flat which doesn't roll off the treble.