Dual Sub Timing and Alignment with Mains

[achugh]

Hi,

This is where I am stuck and need real help. I want to now use the woofers in my front mains to essentially add 2 more sub woofers to make it a 4 sub-woofer setup. In other words, I want my mains to be integrated with my dual sub-woofers. How can I see what is going on now? Using REW I can only send signal to one channel only i.e. either L or R or LFE when I am connected via HDMI and using Java drivers. I do not see any option to send L+LFE and R+LFE and finally L+R+LFE to see how things are integrated and what is my bass response. Did the AVR room Correction did its magic correctly or not?

Thanks in advance for your help.
achugh

 

[John Mulcahy]

Make individual measurements with a timing reference and sum the ones you are interested in using trace arithmetic.

 

[thothsong]

In no way disagreeing, if you want to compare actual simultaneous output against the trace arithmetic, use the Generator to generate the sweep file, and then it's pretty straightforward to use a tool like sox to replicate the sweep into whichever channels you want, and then measure using file playback.

 

[achugh]

Make individual measurements with a timing reference and sum the ones you are interested in using trace arithmetic.

Thank you John Mulcahy for sharing this information. Do you know of any tutorial as well where this is explained better like how to use this approach to test the Mains and Subs integration?

In no way disagreeing, if you want to compare actual simultaneous output against the trace arithmetic, use the Generator to generate the sweep file, and then it's pretty straightforward to use a tool like sox to replicate the sweep into whichever channels you want, and then measure using file playback.

thothsong Thank you for your suggestion as well. I am first of all stuck at gathering the sweep data. Using Java Drivers, I can only send the sweep signal to one channel. I do not see any option to send sweep signal to multiple channels. So I do not understand how I will gather this data to compare with anything programmatically generated.

Are you referring to Sound eXchange audio processor command line utility? Sorry I cannot post ant links yet as I am brand new to this form and are waiting for 10 posts to be posted before my new user restriction is lifted. I am thinking you are talking about this project on sourceforge site. Is that correct? Do you have instructions on how to do what you suggested as I did not get it. I have never used this tool before so I will need some hand holding to get started.

 

[thothsong]

Yes, Sound eXchange. And you don't use the Java output driver in this case. There's more than one way to accomplish it, and I don't know what your full speaker setup is. Assuming you have a 7.1 system and can use the Center channel for the timing reference, then you can do the following. Run REW, click on Generator, and configure it like this:

Click on the WAV button, and save the file somewhere. With these settings the file will be named 1MMeasSweep_20_to_20000_-12_dBFS_48k_Float_L_refR.wav. You can then use these sox commands:

sox 1MMeasSweep_20_to_20000_-12_dBFS_48k_Float_L_refR.wav L+LFE.wav remix 1 0 2 1 0 0 0 0
sox 1MMeasSweep_20_to_20000_-12_dBFS_48k_Float_L_refR.wav R+LFE.wav remix 0 1 2 1 0 0 0 0
sox 1MMeasSweep_20_to_20000_-12_dBFS_48k_Float_L_refR.wav L+R+LFE.wav remix 1 1 2 1 0 0 0 0

to generate 7.1 files with timing on the Center channel, with simultaneous sweeps on L+LFE, R+LFE, and L+R+LFE.

To use one of them, click Measure in REW, select Playback: From file, then click Browse and load the original file that Generator produced. Click Start, and REW will start waiting to hear the timing reference via the mic. Play back one of those multi-sweep files through some means external to REW to complete the measurement.

 

[achugh]

Thank you @thothsong and @John Mulcahy for sharing these instructions.

I saw some YouTube videos and noticed that ASIO4ALL drivers allow a secondary output before generating the files, I thought I should give these drivers a try. When I play through the latest version 2.15 my audio comes out really weird as if something is trying to take control of the audio device so it pulses and the output sound is low. I am unsure if anyone else has faced this problem and knows what I could do to fix this issue.

The other issue I faced is that via Windows 10 Sound Panel, I can play sound from all the 7.1 channels but when I try to play sound from REW generated sweeps I can only generate sound for 5.1 channels. There is no sound coming from BL and BR using the JAVA drivers. Is this a known issue?

I have been watching a fairly new YouTube channel named "Obsessive Compulsive Audiophile" and have been impressed by the work done by this person. In one of his videos, he provided the 9.1.6 atmos files which I believe he thanked you for helping him generate it. When I try to play any of those files, my AVR (Pioneer Elite SC-37) switched from PCM Direct to Dolby Digital Plus as the display. More importantly, I now get sound from SL and BL speakers and the AVR is showing me that I am playing a 5.1 audio file as it does not light up the 7.1 speakers which I do see when I play the Test Audio from Windows 10 Sound Panel or when I watch Dolby Atmos encoded movies.

Does anyone know if REW is capable of generating BL and BR sweeps as PCM sounds yet? Since my AVR is 7.1 only as it is quite old, if REW can generate the sweeps then I do not have to get into playing audio files. I will also need to somehow get the ASIO4ALL to work for me too since it supports audio from two speakers at the same time instead of just one like the current JAVA drivers.

 

[achugh]

I have solved the weird audio output issue for ASIO4ALL drivers. For some reason, I needed more buffers for my NVIDIA HDMI out to AVR. It was defaulting to 512 as the ASIO Buffer Size. Once I increased this size to 576 my audio is now coming out correctly.

I am however noticing that the JAVA drivers are recording a 15db higher sound volume compared to ASIO4ALL throughout the frequency range. It seems to me that somehow the ASIO4ALL is setting the mic volume differently than the JAVA drivers. Is there someplace that I can go and check the mic level of UMIK-1 used by ASIO4ALL drivers? Also, what should I set the ASIO Buffer Size value for UMIK-1 in ASIO4ALL? Do I need any Latency Compensation or any other values set under Advanced options? I have the Kernel Buffers set to 2 by default.

 

[thothsong]

The Atmos files are only useful if your AVR supports DD+ Atmos. If your AVR only supports plain DD+, then you'll only get 5.1 with those files.

With the Java driver, are you seeing 8 selectable channels in REW, or only 6? If you see 8, then try going to REW Preferences, Soundcard, click Set Output Channel Mapping, and click Reset Channel Mapping, and see if that helps. I get full 7.1 with both Java and ASIO4ALL.

For ASIO4ALL, it should be fine to just set the buffer size to 2048.

 

[achugh]

@thothsong My AVR is Pioneer Elite SC-37. It is a 7.1 channel AVR. The product sheet that I downloaded when this receiver was top of the line on the Pioneer website states "Dolby® TrueHD, Dolby Digital Plus, Dolby ProLogic IIz, DTS-HD® Master Audio / High Resolution Audio" in its audio feature set. Back then ATMOS was not even released. It is a plain old 7.1 channel receiver without ATMOS support hence these ATMOS files are not working out for me.

@John Mulcahy The REW sweeps on the AVR show up as PCM and the Windows 10 Sounds settings signal also shows up as PCM on the AVR. The difference is that REW Sweeps using Java drivers only light up 5.1 channel indicators and hence only play 5.1 channels. On the other hand, Windows 10 sound test is able to play all 7.1 channels and the 7.1 channel indicators show up. Are there any plans for REW to support 7.1 channel PCM sweeps like Windows 10?

 

[John Mulcahy]

The REW EXCL Java driver supports as many channels as the interface offers it. It only uses linear PCM, it does not produce any compressed formats.