Check My Measurements? - Home Theater Forum and Systems - HomeTheaterShack.com

 
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post #1 of 9 Old 02-13-13, 04:53 PM Thread Starter
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Join Date: Jan 2013
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Check My Measurements?

OK, I got some good measurements last night after pushing subs around my room for about and hour and a half. I've got 3 subs - 2 new, 1 older that is mismatched - and the placement combinations are seemingly endless! Anyway, I think I've got the bass response as good as it's gonna get without treatment (in the plans).

These measurements were taken with my UMM-6 and legacy audio connections (PC audio out to AVR). I've still got a small ground loop hum at 60hz that I need to hunt down and kill though.

Here's my graphs:

Subs + L/R, Audyssey OFF:



Subs + L/R, Audyssey ON:



Subs + L/R, Audyssey ON/OFF overlayed:



Subs + L/R, Audyssey OFF, full range sweep:



Subs + L/R, Audyssey ON, full range sweep:



Subs + L/R, Audyssey ON/OFF, full range sweep, overlayed:



Subs + L/R Waterfall, Audyssey OFF:



Subs + L/R Waterfall, Audyssey ON:



Drawing of my room with current sub placement:



Ceiling is 8'.

MDAT file:

Alan P2.mdat

The sub response to me looks really good with Audyssey off, but after it's turned on there is some weirdness going on above the crossover point (80hz). Audyssey did however flatten it out nicely between 30-60hz.

On the full range sweeps, Audyssey created a big dip between 90-170hz. This is the "meat" of the mid-bass, correct?

Waterfalls are set to 600ms to get the last of the decay - looks not too bad to me, but what do I know.

After I took these measurements, I had a listen to some demo material I'm familiar with (Audyssey on) and the (for lack of a better word) "richness" was lacking - bass was almost non-existent. Checking the speaker levels in my AVR with the SPL meter in REW showed them to be quite a bit under 75db. Some were off by just a couple db, but the subs were down a good 10-11db. This has been my experience every time I run Audyssey on this system in my room though, so no surprise there.

I wrote down the speaker levels set by Audyssey, then adjusted the FL/FR and subs to as close to 75db (per REW's SPL meter) as I could. WOW! The sound really got "rich" after this - much more bass and mid-bass. Whatever it takes to make me smile I guess. Listening to the same demo material again did most certainly bring a smile to my face. I stayed up way too late enjoying the audio goodness!

I have not taken measurements after adjusting the speaker levels, but plan on doing that tonight.

To anyone reading this, I can't stress enough the importance of experimenting with sub placement - especially if you have multiple and/or mis-matched subs. The inter-reaction between them is key to getting good sound. I'm stunned by how just moving one sub from the front to the back of the room made a world of difference. I also gain matched (thanks Craig!) these subs for the first time last night (was always level matching before) and I think this may have greatly contributed to the results I'm getting.

Thanks to you guys for all your helpful input!

Last edited by AudiocRaver; 02-14-13 at 03:09 AM.
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post #2 of 9 Old 02-13-13, 04:54 PM Thread Starter
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Re: Check My Measurements?

Hmmm...my pics aren't showing up. They show in the preview. Any ideas??
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post #3 of 9 Old 02-13-13, 05:16 PM Thread Starter
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Re: Check My Measurements?

Hmmm...even tried putting the pics up on Photobucket and they still won't show. Anybody know what's going on here?

EDIT: Ok, I think it's because I have to wait an hour after my 5th post. Hopefully the pics will show up then!
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post #4 of 9 Old 02-14-13, 02:57 AM
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Wayne Myers
 
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Re: Check My Measurements?

This is quite strange, when I go into preview mode preparing this post, I can see your plots, but going back to regular viewing mode they disappear.

There are a couple of good threads on uploading and posting plots and photos in the Forum Help / Suggestions area, you might need to repost, going through the instructions step-by-step to make sure something didn't get missed.

Having glanced through your "invisible" plots, your no-Audyssey plots look great, a lot of people never get their pre-EQ plots looking at nice. You have clearly done some good detective work with your sub placement.

There has to be some phase issue that Audyssey is having trouble dealing with, causing that dip when it is activated, or perhaps an overlooked setting somewhere. There may be some more sub/crossover/phase experimentation called for to get that straightened out. Other than that dip, Audyssey is cleaning up the curve nicely. But that dip obviously has to go.

It seems to be a reality that even the best automated room correction software needs some hand tuning from time to time. That is one nice thing about devices that allow you to get in and change filter parameters if you need to.

Once you get those plots viewable, no doubt others will have some great suggestions for you. You are off to a good start.

Best of luck.

EDIT: Your plots are showing up now, since I did a minor edit, so "never mind" on re-posting. It's a mystery.

Last edited by AudiocRaver; 02-14-13 at 03:13 AM. Reason: No need to repost.
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post #5 of 9 Old 02-14-13, 06:13 AM
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Re: Check My Measurements?

This type of SW placement can result in smooth SPL results but really should have compensation for the large difference in distance of the SWs from the LP.

Does your version of Audyssey have the ability to adjust the SW distance differently for 2 SW? If so place SW 1 on one SW output and SW 2 and 3 on the other. That may help the large nul with Audyssey.

Be sure to follow the recommended Audyssey process using mutliple mic locations for setup. To really evaluate how well Audyssey has worked it is necessary to measure with REW at the same 8? mic locations and then average the measurements.
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post #6 of 9 Old 02-14-13, 09:52 AM Thread Starter
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Re: Check My Measurements?

Quote:
AudiocRaver wrote: View Post
Having glanced through your "invisible" plots, your no-Audyssey plots look great, a lot of people never get their pre-EQ plots looking at nice. You have clearly done some good detective work with your sub placement.

There has to be some phase issue that Audyssey is having trouble dealing with, causing that dip when it is activated, or perhaps an overlooked setting somewhere. There may be some more sub/crossover/phase experimentation called for to get that straightened out. Other than that dip, Audyssey is cleaning up the curve nicely. But that dip obviously has to go.
Thanks for that, exactly what I wanted to hear, confirming that I'm not a total idiot and actually can read graphs.

I'm thinking that the big dip that Audyssey is creating may be caused by my front speakers.

When I run Audyssey, sometimes I'll get a phase error with the FL or FR speaker. I've checked the wires to the speakers a couple of times to be sure, but haven't opened them up yet to check the internal wiring - something I need to do. Also, it may have something to do with the 20 year old crossovers inside my mains (Klipschorns). I'll have to do some investigating for sure.

Quote:
jtalden wrote: View Post
This type of SW placement can result in smooth SPL results but really should have compensation for the large difference in distance of the SWs from the LP.

Does your version of Audyssey have the ability to adjust the SW distance differently for 2 SW? If so place SW 1 on one SW output and SW 2 and 3 on the other. That may help the large nul with Audyssey.

Be sure to follow the recommended Audyssey process using mutliple mic locations for setup. To really evaluate how well Audyssey has worked it is necessary to measure with REW at the same 8? mic locations and then average the measurements.
My version of Audyssey (XT) does not allow me to adjust the subs individually. Is there some sort of outboard device that can do this (ala Antimode, MiniDSP)?

I'll re-do my Audyssey setup using all 8 positions and hope for better results. Like I said, I was in a hurry and thought that 4 positions would get me "close enough" for some measurements.
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post #7 of 9 Old 02-14-13, 11:42 PM
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Re: Check My Measurements?

I have no experience with either of those units. You really only need 1 (or 2) channels capable of providing delay so I would expect the miniDSP to handle the job easily. It is a popular unit and a very flexible design. The manual is a good resource if no users comment. I use the DCX2496 which is overkill for your situation.

Considering that delay is all that it needed and that the improvement may not be remarkable, it may not be worth the investment. You could try using only SWs 2 and 3 and see if that improves the Audyssey response significantly.

The other experiment you may want to try is to run Audyssey with the LP moved forward 2-3 ft to get further from the rear wall. Sitting close to a wall can be difficult to EQ. It may not be as practical for your decor, but at least you will find out if it is a significant issue.

In my room I found that 7-8 mic positions was a enough for very repeatable results using Audyssey XT. Using less than that provided more variable results. I am sure all situations are a little different, but it is best to use all 8 positions unless testing indicates that fewer positions are sufficient for your situation.
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post #8 of 9 Old 02-15-13, 12:46 PM Thread Starter
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Re: Check My Measurements?

Just FYI - my room drawing ain't the best. The chairs are actually about 4 feet from the back wall.

I re-ran Audyssey last night with all 8 positions and ended up with this (subs + FL/R, Audyssey on):



Gettin' there, gettin' there.....sounds really really good to my ears, though.
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post #9 of 9 Old 02-15-13, 01:07 PM
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Re: Check My Measurements?

It looks pretty good - particularly if that is just one mic position.
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