Reduce Sub Alignment Complexity By Centering 2-Seat Couch on Center Channel?

[kalakasan]

I'm in the preliminary throes of learning how to tune my recently finished 7.4.4 "modest" theater room (2100 cu feet). Since I've never done this before, I'm trying to be patient and read as much as I can on the various approaches to the subject, but to be honest, so far much of it is over my head. I do have REW up and running on an older i3 Acer laptop, although try as I might, I cannot get it to work with ASIO4all. So I'm using Java at the moment, not sure if that's enough to properly align my 4 VBSS subs.

As I glanced around the room this evening, it struck me that by moving my 2-seat couch centered on the center speaker, both seat occupants would have an equal sonic experience - but probably not as good as having one seat centered on axis. However, given what can be done with apps like REW and others (MSO), perhaps the difference would be negligible? Is my intuition wrong on this idea?

 

[John Mulcahy]

You can get a good idea of the nature of the low frequency changes using REW's room simulator. With a single subwoofer low frequency behaviour is better off the central axis to avoid the modal nulls that occur along it, but with a pair of subs placed symmetrically across the width there is very little effect from moving to either side below a couple of hundred Hz.

 

[kalakasan]

Thanks for the reply.

I posted the message below on AVSforum and didn't receive any replies, so I'm posting it here, hopefully with better results:

I've also been struggling as others have with getting ASIO4all to work in REW. I'm on an old Acer laptop, with the latest Windows 10 updates. I've plied through the detailed ASIO setup in the guide, including troubleshooting steps to no avail. I attempted this several months ago with a total of 3 laptops (old and new) with the same negative result, but thought I'd give it another go since I hate the feeling of defeat.

All I can offer at this point in terms of possible clues (given the many possible points of failure) is that although I am able to successfully enable 7.1 audio in Windows sound settings (using the REW guide), when I click on each of the "test" speaker icons in the Windows dialogue box, there is no sound heard through my Denon 3700. I switched the Denon mode to Dolby Surround, hoping to hear something, but no joy. I have also noticed that if I unplug the HDMI cable from my laptop the Windows speaker config will revert to 2 channel stereo. Bear in mind that I have completely disabled the laptop internal 2 channel audio. I also disabled my built-in laptop webcam in Device Manager.

I'm too familiar at this point with loading and checking devices in ASIO4all's control panel - I disable everything except the HDMI connected device (Denon) and Umik devices, and hover over the icons to see that 8 Denon channels and 2 Umik channels are available and active. I've reloaded ASIO4all, quit and restarted REW, rebooted my laptop, tried Flexasio (same result), scoured for hours the multitude of forums looking for possible clues and solutions and still no answers.

Hopefully someone can offer insights to help resolve this nagging issue? Thanks!

 

[John Mulcahy]

The windows testing is not particularly relevant since it usually sends encoded content, but REW uses the HDMI linear PCM channels. The Denon will need to be in a mode that says it accepts multichannel linear PCM and the HDMI input also needs to accept, some don't - front panel inputs on some processors, for example. Note also that the Windows level controls are active for the output so check the Levels setting on the Windows Properties for the Denon Playback device entry.

 

[kalakasan]

Not sure I understand all of your points, but I redid the Windows audio setup steps again to make sure they were set up correctly. Then, as per instructions, I used windows recorder to test the mic input. My Denon 3700 input is a rear HDMI connection (BluRay) set to multi-channel stereo. The windows speaker configuration was set to stereo. In this mode, recorded mic audio was present on the front left and right speakers. However, when switching to 7.1 mode and replaying the same file, the player app threw an error message with no playback possible.

So the question is, why is stereo playback being decoded properly by the Denon and 7.1 fails? I have also swapped HDMI cables - same outcome. My Acer laptop is circa 2013. Are there differences in HDMI hardware between then an now that might explain this behavior? Windows does correctly identify the connection as an "hdmi jack," and all 8 channels show up in windows configuration as well as ASIO4all.

Finally, when running the check levels option in REW setup, the output meter shows a strong and consistent level, indicating to me that REW is generating signal - it's just not being transmitted through the hdmi cable or is not being decoded properly by the AVR.

A head scratcher!

Edit: When I switch to 7.1 and use the newer Windows Sound recorder for playback of the mic test file, there is no error message, however there is still no audio on playback.

 

[John Mulcahy]

I don't know the Denon, but as far as I can tell "multichannel stereo" is not the correct mode to use. According to the manual it should be set to "Multi Ch In". There should be some indication on the Denon when the mode is configured for multichannel linear PCM. That format dates back to 2008, but that doesn't necessarily mean a 2013 laptop supports it over its HDMI connection.

 

[kalakasan]

Yes I did notice the "Multi Ch In" reference, but was unable to ferret it out of the on-screen Denon AVR setup/menu options. I believe 'Multi Ch in' is normally available under the Denon "music playback" options list, per their online guide, but it is missing in my menu presentation. Another mystery. I'll probably have to contact Denon, unless someone here with a Denon AVR can provide some enlightenment. Thanks.

 

[John Mulcahy]

Perhaps it does not appear if the connected device is not providing it.

 

[kalakasan]

So I switched to my wife's laptop and everything went swimmingly until I ran a level check in REW setup and the sound is distorted. I read about upping the ASIO4all buffer size, but it didn't work. I feel like I'm getting so close, but apparently miss REW doesn't want to give up her secrets too easily. Anything to try besides buffer size?

 

[John Mulcahy]

Distorted meaning choppy and dropping in and out or something else? Perhaps time to try FlexASIO, now that you know the basic connectivity is there.

 

[kalakasan]

Distorted meaning choppy and dropping in and out or something else? Perhaps time to try FlexASIO, now that you know the basic connectivity is there.

Very rough sounding distortion, no drop outs. I'll try FLEXASIO

 

[kalakasan]

Flexasio was a fail (no inputs nor outputs found) even though I tried many different configurations in the flexgui app. I think I'm going to move on to Java only. I've searched the forums, but is there a singular REW resourced focused on Java? Also, it does appear 2 channels are being passed from REW to my Denon in HDMI mode. Is that equivalent to Java in functionality? If so, which one should I use?

 

[John Mulcahy]

First time I've heard of FlexASIO not working, but I've only used REW's own FlexASIO control panel, not FlexGUI.

On Windows JavaSound only provides stereo channels, so you will only have the left and right channels. If they are configured in the AVR with a bass management crossover and the AVR mode allows bass redirection the sub will get redirected content from whichever channel you send the signal to.

 

[kalakasan]

I tried using REW's Flexasio control panel and am wondering what the preferred settings are (MME, DirectSound, etc)

 

[John Mulcahy]

I normally use WASAPI and 1024 buffer size.

 

[kalakasan]

As soon as I changed from 44k to 48k in REW preferences, things are working as advertised. Huge baby step! I have four VBSS subs, 2 in front, one on the back wall and another towards the back of the right wall. They are tuned to 20hz. They will not be moving, so my optimizations will proceed from that constant. Next steps...