Official HSU ULS-15 Thread - Page 77

Originally Posted by AustinJerry

Using REW, while running sweeps of the 20-200 Hz range, adjust the sub distance settings in small increments, observing the response in the splice region. .

Originally Posted by shumi_9

You do this in two channel mode or multichannel?

Originally Posted by AustinJerry

I ask because other Audyssey users who have seen issues around the splice between the mains and the subs have improved the smoothness of the splice by adjusting the distance setting for the sub(s). Using REW, while running sweeps of the 20-200 Hz range, adjust the sub distance settings in small increments, observing the response in the splice region. Once you have determined the distance setting that produces the smoothest response, listen to the bass to make sure you hear an improvement. I use this technique myself. As soon as I get to my real computer, I'll attach some REW graphs to demonstrate the improvement.

Originally Posted by AustinJerry

I have attached the REW graph showing the improvement from adjusting the sub distances. The green line shows Audyssey engaged (DEQ off) with default distances, as calculated by the calibration. The red line shows the response after tweaking the sub distances to find the smoothest response. Speaker/sub crossover is 80 Hz.

Originally Posted by AustinJerry

I have attached the REW graph showing the improvement from adjusting the sub distances. The green line shows Audyssey engaged (DEQ off) with default distances, as calculated by the calibration. The red line shows the response after tweaking the sub distances to find the smoothest response. Speaker/sub crossover is 80 Hz.

Originally Posted by AustinJerry

I ask because other Audyssey users who have seen issues around the splice between the mains and the subs have improved the smoothness of the splice by adjusting the distance setting for the sub(s). Using REW, while running sweeps of the 20-200 Hz range, adjust the sub distance settings in small increments, observing the response in the splice region. Once you have determined the distance setting that produces the smoothest response, listen to the bass to make sure you hear an improvement. I use this technique myself. As soon as I get to my real computer, I'll attach some REW graphs to demonstrate the improvement.

Originally Posted by Karn


Thanks for the info this is at my crossover so you are probably right and I have heard that's a big problem area. I'll take a look at this when I get my mic set up. I was taking a look at that standing wave calculater from Toole and it looks like I'm also sitting near a 80hz null both length and width wise so there could be a lot going on there. If that's the case I could probably do a combination, move the crossover out of the sub null and smooth out the splice by shifting the sub distance as you mention. I'll try and post some graphs as well as that looks like a really nice improvement. Looks like you did a great job with your response too, that's awesome! I'm kind of expecting the worst when I see mine but at least I'll be able to see what I have to fix. Should be a fun process!

Originally Posted by hometheatergeek


So which way did you change. Subs farther away or closer? Most of the time I have to set the subs farther then what is calculated. In your before and after it looks like you had to shorten the distance...or am I reading that wrong?

Originally Posted by AustinJerry

Remember, the most important step is to find the right location for the sub, using measurement tools like REW, and techniques like placing the sub in the MLP and measuring at each potential location around the room (Dr. Hsu repeatedly recommends this technique, for good reasons). The second step is the room calibration. The last step (for some), is the distance adjustment, which I call fine-tuning.

Originally Posted by Karn

I just finished wiring up my rears

Originally Posted by hjones

Wow, that had to hurt

Originally Posted by Karn

Well I finally finished moving everything and it looks like the audyssey before graph looks better but the after graph looks worse.

Originally Posted by dr_hsu

Due to WAF factor, I only have a VTF-2 MK2 in my house. When I want great bass, all I have to do is go into work... Our demo room has two 15Hs, and two ULSs. Strange as it may sound, I don't listen very loudly. I feel sick if I sit in front of one of the 15Hs when playing the haunting.

Originally Posted by Auditor55

Do you really get sick? You seem to be joking kind of.

Originally Posted by dr_hsu

Can you post the graphs?

Originally Posted by Karn

Oh sorry didn't realize that actually posted I was going to put more info in there so I thought I just closed out of my browser. I'm not sure if I can post the graphs or not but I'll try:

Here's the most recent version with the sub next to the couch:
http://installer.audyssey.com/Instal...resultsID=1978

Here's the prior version with the sub in the corner:
http://installer.audyssey.com/Instal...resultsID=1977

Basically with the sub in the corner I had a small dip in the low bass and a big dip around 80 hz. With the sub near the couch I have a smooth response and then a big dip in the low bass. Audyssey was able to EQ the prior dip in the low bass and most of the 80hz dip but did not EQ the low bass at the new position so the after grapth still has the dip. Trying to boost that low bass might eat all of the power though so it may just be better to try and get better sound over a sligltly less frequency range. Overall the beginning graphs look much better for the new position and really smoothed things out. Even though both after graphs are flat in the mid bass I'm sure there is less EQ going on in the new placement.

I was able to listen to a couple movies as well and it sounds really good. The new Tron was on after I set everything up and the bass was great. I plan on putting something good on tonight and just relaxing. I do have the sub running wirelessly and it's going well so far haven't had any issues with it. I have a fair amount of wireless devices but no interferance.

Originally Posted by dr_hsu

Sorry. Was not able to see your graphs since they ask for login id, etc.

Originally Posted by AustinJerry

Audyssey calculates the F3 for the sub, and will not apply any correction below that frequency. It is possible that with the new sub location, Audyssey is seeing a higher F3 value than before, which could explain no correction below approx 20 Hz.

By the way, the Audyssey Pro graphs are not that good at depicting the true response. Do you have an independent measuring tool like REW or OmniMic?

BTW, the correction above 20 Hz doesn't look too bad.

Originally Posted by Karn

Sorry about that hopefully this works

Originally Posted by dr_hsu

What is the vertical scale? 5 dB/div? Is the darker horizontal bar the same SPL in both graphs? Is the peak in the lower graph at 16 Hz? Is the graph going down to 2 Hz?

First, few material have 10 Hz in the program. Second, even when present, the 10 Hz level relative to the sum of the energy at all the other bass frequencies is probably miniscule. Hence, even if the sub can reproduce the 10 Hz faithfully and thus maintain the same output relative to the other bass frequencies, the dB reading that you get on the SPL meter will not change significantly whether the 10 Hz is there or not. To further compound the situation, even at the same dB output, 10 Hz would be much harder to detect than the higher bass. The presence of the higher bass tend to have a great masking effect.

Originally Posted by dr_hsu

What is the vertical scale? 5 dB/div? Is the darker horizontal bar the same SPL in both graphs? Is the peak in the lower graph at 16 Hz? Is the graph going down to 2 Hz?

Originally Posted by AustinJerry

Hi Dr. Hsu,

I am attaching the explanation of the Pro graph scale, as described by Chris K., the Audyssey CTO.

Originally Posted by dr_hsu

Are those curves for just the sub or does it include the main speakers?

If the curve starts at 20 Hz, the response shown goes up to 1 kHz or so! The front position appears to be much better for the deep bass. The back position is better for the mid bass. Since it's harder to have deep bass headroom, I would use the front position. Note: I assumed that the dark horizontal line is the same SPL in both curves, and the same drive signal was used to produce both graphs.

Originally Posted by AustinJerry

Dr. Hsu, please keep in mind that the Audysssey Pro "after" graph (on the right) is a derived graph, not actual measured in-room response. I have attached my Pro sub graph (three ULS-15's), and you can see that the after graph shows flat to 500 Hz. Even the before graph, which is measured, shows response up to 400 Hz. BTW, the dark horizontal line represents 75 Hz.

The Audyssey Pro graphs have received considerable discussion on the AVS Forum Audyssey Pro Kit thread. Most participants agree that independent measurements more accurately describe what is actually happening with bass in the listening room.

I believe you are correct--the front placement does look like the better choice.

Originally Posted by shumi_9

Sorry dr_hsu, I can not move the seat. It is placed in the middle of the room, 12 ft from the front wall. I have two constraints: 1) location is optimum for the front Dunlavy speakers which must have a 75 degree spacing, and 2) the 12 foot distance for the 120" projection screen is ideal for viewing. Does this change which type of sub I should purchase and the number of subs?