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Is an EMM-6 & an an XLR-to-USB adapter considered a USB microphone?

1805 Views 31 Replies 5 Participants Last post by pepar, Jul 8, 2021

pepar

Discussion Starter · Jun 28, 2021

For the purposes of using REW to gain match subs and then to supply MSO with measurements, does a Dayton EMM-6 and the XLR-to-USB adapter that came with my Emotiva XMC-1 set up in REW like a USB mic where one does not need to have a reference SPL meter?

1 - 20 of 32 Posts

andyc56

· #2 · Jun 30, 2021

pepar said:
For the purposes of using REW to gain match subs and then to supply MSO with measurements, does a Dayton EMM-6 and the XLR-to-USB adapter that came with my Emotiva XMC-1 set up in REW like a USB mic where one does not need to have a reference SPL meter?

I must admit I had never heard of XLR-to-USB adapters before, so I did a search and found this one. That particular one will turn your XLR mic into a USB mic, as it provides the required +48 Volt phantom power to the mic, and has its own mic preamp. I don't know about the one that comes with the XMC-1 though. You might ask around in the Emotiva forums to see if it provides those features (mic preamp and +48 Volt phantom power).

The fact that the miniDSP UMIK-1 makes it so you don't need an SPL meter stems from the inclusion of an SPL cal factor in its frequency response cal file, and that REW has code that's specifically written to translate that vendor-specific number so that it can calculate SPL. It's not an intrinsic property of USB mics per se. So you won't have absolute SPL capability even if the adapter has the phantom power and preamp. But that actually doesn't matter very much, unless you care about absolute accuracy in SPL readings. MSO only cares about relative levels for response vs. frequency, so when you go to do the cal with pink noise, you can adjust the level so it's about 75 dB SPL and just enter that as the number. The only requirement with MSO is to not change cal midstream. Just do the cal right before measuring, and keep that same cal for all the measurements you do.

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pepar

Discussion Starter · #3 · Jun 30, 2021

Thanks, @andyc56, that's really the answer I was seeking. I've used this mic/adapter before for the Emo Dirac, but it's been quite a while. Now, after adding another SuperChunk trap, I want to redo the calibration from top to bottom this time adding MSO to the "bottom." As this will depend on REW, I wanted to make sure my setup was correct. Will be using ASIO and HDMI for the laptop audio's output and that's new to me as well. So, apparently, I lapsed back to unnerved noobhood.

rcohen

· #4 · Jul 4, 2021

I've used this smalll/cheap USB mixer with phantom power:

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It works great as a USB mic, with a few caveats:
1) Having input and output on the same device make it a bit trickier to set up with ASIO4ALL.
2) One time I was using the input and output at the same time, hit the wrong button on the mixer, and blew the speaker I was testing with a feedback loop. So, if you do use a mixer, don't use both at the same time, and if you do, don't hit the wrong button.
3) The SPL needs to be calibrated with a phone or SPL meter, if you need calibrated SPL. This is probably true of any USB to XLR option.

On the positive side, I found that using phantom power plus the Cross Spectrum EMM-6 had 20db better SNR than my UMIK-1.
Seems like MiniDSP solved the need for that with the UMIK-2, though.
The extra SNR was nice for cleaner graphs and measuring the room noise floor, but there was no audible benefit for calibrations.

pepar

Discussion Starter · #5 · Jul 4, 2021

Ahh, boy, I am set up with my Dayton EMM-6, phantom power and the USB-to-balanced mic adapter that came with my Emotiva. This is the adapter, minus the Emo logo. I have set it up with REW/ASIO4All and an HDMI to my pre/pro.

At this point I am wading through the MSO documentation and trying to grok "time synchronized measurements." I am unclear if this "To obtain time-synchronized measurements with REW and an XLR microphone such as the Parts Express EMM-6, you must use a separate sound device such as an external USB sound device with a microphone input." means I am good to go using the EMM-6 with the "external USB sound device with a microphone input" or if that is referring to yet another device?

From these posts I now get that my EMM-6/mic/USB adapter combo does not have meta data that calibrates the SPL, but that it isn't really needed.

So, on to setting up REW and my pre/pro to generate the time-synchronized measurements!

andyc56

· #6 · Jul 4, 2021

pepar said:
At this point I am wading through the MSO documentation and trying to grok "time synchronized measurements." I am unclear if this "To obtain time-synchronized measurements with REW and an XLR microphone such as the Parts Express EMM-6, you must use a separate sound device such as an external USB sound device with a microphone input." means I am good to go using the EMM-6 with the "external USB sound device with a microphone input" or if that is referring to yet another device?

It's just saying you need a sound device containing a mic preamp and providing a digital signal that the computer can pick up to make the XLR mic work. The adapter you mentioned apparently has such a preamp with +48V phantom power, and an A/D converter with digital hardware that produces a USB signal. So the mic can be used as a USB mic as we previously discussed. Technically the adapter is a "separate sound device." This means for time-synchronized measurements, you can use the REW acoustic timing reference. Do not use a hardware loopback. Just remember to use the same speaker for the acoustic timing reference for all measurements, and make sure the speaker is not a sub. It has to be able to reproduce the timing reference, which is a chirp that starts at 5 kHz and sweeps up.

pepar

Discussion Starter · #7 · Jul 5, 2021

Thanks. I’ve alternated rereading your tutorial’s section on this with the REW section. On REW 5.20 at least, the timing reference check box phrasings were different enough to introduce a bit of uncertainty; their verbiage is something like “offset measurement with loopback reference” and not the straightforward “use loopback as timing reference.” I needed to have a better understanding of what the references were doing to get that those were the same.

Jeff

andyc56

· #8 · Jul 5, 2021

pepar said:
Thanks. I’ve alternated rereading your tutorial’s section on this with the REW section. On REW 5.20 at least, the timing reference check box phrasings were different enough to introduce a bit of uncertainty; their verbiage is something like “offset measurement with loopback reference” and not the straightforward “use loopback as timing reference.” I needed to have a better understanding of what the references were doing to get that those were the same.

Just to repeat, a loopback timing reference should never be used with a USB mic (or equivalent such as your setup). Instead, use an acoustic timing reference in REW.

Also, it might be a good idea to check out the MSO Tutorial Video thread. @fattire has done an outstanding job with this video that spans almost two hours. It's using a pre-release version of MSO that adds a couple of wizards that remove almost all the pain from setting up your project. There's a download link to the pre-release version in the first post of that thread. The code of the pre-release version is stable, it's just that the documentation is undergoing a major revision. There's a completely rewritten and finished tutorial in the CHM help file of the pre-release that you can find by choosing Help, Tutorial from the main menu. The tutorial video follows the general pattern of this new tutorial section in the documentation.

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pepar

Discussion Starter · #9 · Jul 5, 2021

That's right, a loopback should never be used with a USB mic! Thanks for the link to the video; I had already found it but didn't have the time to watch. I have temporarily set REW/MSO aside to get my theater up for some guests. Once that occasion has passed I will return and try the pre-release.

fattire

· #10 · Jul 6, 2021

pepar said:
That's right, a loopback should never be used with a USB mic! Thanks for the link to the video; I had already found it but didn't have the time to watch. I have temporarily set REW/MSO aside to get my theater up for some guests. Once that occasion has passed I will return and try the pre-release.

If you have questions on the MSO video, let me know. I'm happy to help. As mentioned by Andy above, make sure to use the code I linked in the tutorial post to get the benefits of the awesome new wizards he's added. They make life much easier!

Regarding the REW/ASIO frustration .... you technically only need to be able to measure 2 channels in REW to get usable measurements for MSO: one to supply the acoustic timing reference and one other to actually measure. Stereo is good enough. I'm a Mac user, but I see a lot of folks struggling with ASIO on Windows.

Use the pre-out section of your AVR and temporarily connect the input to the miniDSP to the Left-Front channel pre-out of the AVR. Temporarily disconnect the Left Front speaker. Sweep the left front (which is now just the subs) and use the Right Front as the timing reference and you're good to go. Don't forget to set the L&R speakers to "Large", zero out all delays and gains in the AVR as well as disable any room EQ software (YPAO, Audyessy, Dirac, ARC, etc.) before taking measurements. For a sub-only optimization, you can use the LFE output, but if you're having trouble getting measurements, this is a good workaround.

I'm coming off PTO and going back to work tomorrow, but hope to get the chance to do a video on "REW Measurements for MSO" sometime this week.

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pepar

Discussion Starter · #11 · Jul 6, 2021

Thanks for you efforts on the video, @fattire. I watched a bit last evening.

WRT my subwoofer subsystem configuration, I am using a pre/pro (Emotiva XMC-1) with mono subwoofer balanced output going to a MiniDSP 2x4 balanced which (at this time merely) splits it into two and delays one before the the signals travel to the amps/subs. I have easy access to the front and rear amps that power the front and rear subs so that will I get individual measurements.

With this gear, how would I effect the acoustical timing reference? I was thinking it was all handled through the HDMI connection from laptop to pre/pro, i.e. the "non-sub" channel I designate as the reference speaker is swept by REW just before it sweeps the sub.

Jeff

fattire

· #12 · Jul 6, 2021

pepar said:
Thanks for you efforts on the video, @fattire. I watched a bit last evening.

WRT my subwoofer subsystem configuration, I am using a pre/pro (Emotiva XMC-1) with mono subwoofer balanced output going to a MiniDSP 2x4 balanced which (at this time merely) splits it into two and delays one before the the signals travel to the amps/subs. I have easy access to the front and rear amps that power the front and rear subs so that will I get individual measurements.

With this gear, how would I effect the acoustical timing reference? I was thinking it was all handled through the HDMI connection from laptop to pre/pro, i.e. the "non-sub" channel I designate as the reference speaker is swept by REW just before it sweeps the sub.

Jeff

That's 100% correct. REW -> HDMI -> XMC-1.

In the REW Measurement Sweep UI, there should be a field to tell it to use an acoustic timing reference. Then towards the bottom, there's a "Ref output" selection with a pair of drop-downs. The specifics will be slightly different with ASIO on Windows, but you'll need to select the HDMI "device" as the output and then select the acoustic timing channel to use. I don't remember how the Windows channel numbers actually line up to output channels so you'll need to look that up.

"Output" is the channel you want to sweep/measure. "Ref Output" is the channel to use for the acoustic timing reference.

Make sure you zero out any gains/delays/PEQs you have on your miniDSP before getting any measurements. I mentioned that for the AVR, but forgot to remind on the miniDSP as well.

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pepar

Discussion Starter · #13 · Jul 6, 2021

I think I have internalized all of this part of the process and that it will go smooth when I get back to MSO.

I do have some questions about mic placement. Ninety-eight percent of my home tjheather usage is solo with me sitting in the MLP, one of six LaZboys that is the center, rear seat of a 2-row x 3-seat layout. Much of the other usage would be myself and one other person in the second row. (Virtually never does anyone sit in the front row.). So I am looking at optimizing for the three seats in the rear row. What is the optimal mic placement for my scenario? The optimal distance between mic placements?

For context, with Dirac Live I go with "chair" and the UI gives me mic locations that are ~6"-8" apart.

Jeff

fattire

· #14 · Jul 6, 2021

For the MSO calibration, since you only care about the three seats in row 2 so you'll want to measure each sub individually at each of those seats. MSO prioritizes the MLP over the other seats so it will still end up with a great frequency response. You will designate one position as the MLP when you do the MSO optimization setups.

You can measure as many positions as you like for MSO, but at a minimum, measure each sub at each listening position, with the mic placed as closed to head position as possible. You do not want to measure one position with a small cube of measurements as that can result in a big reduction in head room in the MSO optimization process.

Once the MSO optimization is done, and you have input all the configs into the miniDSP, then you run your Dirac calibration however you like. That's where you can use the "chair" option and get things super tight for just the MLP.

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pepar

Discussion Starter · #15 · Jul 6, 2021

So, one measurement per sub at each of the three seats with the mic POSITIONED in the middle of the listeners' heads?

fattire

· #16 · Jul 6, 2021

pepar said:
So, one measurement per sub at each of the three seats with the mic POSITIONED in the middle of the listeners' heads?

Exactly

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pepar

Discussion Starter · #17 · Jul 6, 2021

One more for now; I use gain-matching on my subs; Is there anything MSO does that could interfere with that? Or does ot only adjust EQ and delay?

andyc56

· #18 · Jul 6, 2021 (Edited)

pepar said:
One more for now; I use gain-matching on my subs; Is there anything MSO does that could interfere with that? Or does ot only adjust EQ and delay?

It's your choice. If you want to preserve your gain matching to maximize output, the way to do that is to put only delays on the individual subs, no gain blocks or PEQs at all. Then put PEQs as shared sub filters (which end up on the miniDSP input channel only).

Edit: For that setup you'll also need a single gain block in the shared sub channel (miniDSP input channel) to set the reference level - but no individual gain blocks (output channel gains).

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pepar

Discussion Starter · #19 · Jul 6, 2021

Good stuff! Thanks again!!

sam_adams

· #20 · Jul 7, 2021

pepar said:
Ahh, boy, I am set up with my Dayton EMM-6, phantom power and the USB-to-balanced mic adapter that came with my Emotiva. This is the adapter, minus the Emo logo. I have set it up with REW/ASIO4All and an HDMI to my pre/pro.

Pay attention to your sample rates and bit depths in REW when using that cable. If the Emotiva cable has the same specs as the linked one, you are limited to 16 bits at 44.1KHz or 48 KHz.

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