DIY Speaker measurement

[headshake]

This I also a $200 investment

My scarlett was used. Lots of 2i2 2nd gens floating about. So you can save a little bit if you don't mind used.

All of these mics are going to measure a little differently than one another. I'd mostly trust a result but want to use many mics.

A local speaker building buddy purchased 3 mics setups and the omni mic won. It is also not cheap, but cheaper than the expensive mics.

 

[nurmdog]

So I have REW running on MAC OS, the umm-6, and I believe I have correctly put in the calibration txt file.
I am running Measure and with three different speakers am I getting a pretty big spike at 2khz and harmonics of that frequency. It's kinda ugly. I am assuming I missed something ? Any thoughts?

 

[fluid]

Something has for sure gone wrong there. There isn't many options when using a USB mic. I would start by having at look at this video

and take a look at the MiniDSP guide as the Dayton is basically the same

https://www.minidsp.com/applications/acoustic-measurements/umik-1-setup-with-rew

follow those steps and see if you have done anything different, check your output to the speaker using the generator and pink noise and then look at the input meters to see what is coming back in. Check sample rates are correct and make sure than there are no windows audio enhancements or weird settings turned on that you don't know about.

 

[nurmdog]

Thanks fluid, I watched the video and followed directions. I was making one mistake, being silly, I was pointing the omni mic as if it was a shotgun mic. I ran measurements again with the mic pointing up and it now has less of those 2k harmonics but it's still there. I Tried 44k and 48k sample both, didn't matter.

Here is the pink noise

This issue still happens with two completely different DAC/Amp/Speaker combinations.

I have turned in a support ticket with Parts Express, I hope that this particular mic is broken and a replacement will fix it.

 

[Jdunk54nl]

I am not 100% sure what you are doing wrong, but this is what a graph should look like... Note this is 1/6 smoothing and a moving mic measurement method with periodic pink noise.

But even 1/48 smoothing isn't as messy as yours...

 

[Jdunk54nl]

A Sweep gives comb filtering noise when not smoothed and not gated.

But smooth it even to 1/48 and it cleans a lot of it up. I would suggest either 1/6 or psychoacoustic smoothing as you are starting out.

 

[Jdunk54nl]

When you gate the response, you lose resolution and low frequency information, but it cleans up the comb filtering and gets rid of the reflections.

This is the same measurements above: I gated this one to about 3ms because there is definitely some reflection happening right after that (another bigger peak). To change gate of a measurement click the IR windows at the top next to SLP meter. Then the box on the left part of my screen shows up. Right window is the more important one. The blue box is the new gated window.

This results in a 333hz resolution, which isn't very good, but better than including all of the reflections. This also truncates everything 333hz as it would not be accurate. This is what the new measurements look like after gating.

Compared to ungated measurement: (same picture as above post)

 

[Jdunk54nl]

Note, the above is more explaining why you get that comb filtering effect (all of the craziness that looks like nothing makes sense).

I use periodic pink noise and moving mic measurements for EQ work because it has been shown many times the predicted in room response is pretty close to this moving mic steady state.

 

[nurmdog]

So I tried pink noise, periodic and random, no change.
I tried putting it on a pillow rather than my desk, no change.
I used the RTA tool in a silent room, no change, those spikes were still there.
I moved the USB cable from the eGPU I have (it's connected with tbolt4) to be directly connected to my MAC Mini. That fixed it. I really don't know why the Black Magic Design eGPU would create noise at 2k over the USB, but it did.

Thank you everyone for your help, it's great to have a place where people encourage this hobby. I plan to post my first speaker measurement project elsewhere soon.

 

[fluid]

Thanks fluid, I watched the video and followed directions. I was making one mistake, being silly, I was pointing the omni mic as if it was a shotgun mic. I ran measurements again with the mic pointing up and it now has less of those 2k harmonics but it's still there.

You weren't being silly, normally you would make measurements with the mic pointing directly at the speaker as that is the axis that most mics are calibrated to with a 0 deg file.

Pointing the mic up in the air is generally better for in room measurement but when you do so you need another calibration file at 90 degrees to compensate for the frequency response difference there will be. I don't know if Dayton supplies a 90 degree cal file or if it can be downloaded. If not stick to 0 deg. A 90 degree cal file can be made at home with surprising accuracy, the process is not straightforward but it works.

https://johnr.hifizine.com/2014/09/how-to-make-a-90-degree-calibration-file/

 

[CauliflowerEars]

I’d suggest a focusrite 2i2 or motu m2 and a emm-6 or similar xlr microphone.

You can reach the limits of a usb microphone, you can’t really reach limits from a xlr mic and interface. The xlr mic and mic interface allows for most software analysis too with loopback possibilities for real time impulse response and phase measurements.

Would a Behringer UMC202hd interface be good for amateur REW room measurements and treatment? With the Behringer ECM8000 mic.
From my understanding, for such a case, the ECM8000 would be good enough?
I also would rather spend money on upgrading the system and treating the room. A friend of mine already has the Behringer UMC202hd interface, so the total cost would be lowered.

Also considered the Dayton Audio iMM-6, but sounds it'd be worse than Behringer?
Unless it's absolutely necessary to get the UMIK-1 ...

 

[Jdunk54nl]

Would a Behringer UMC202hd interface be good for amateur REW room measurements and treatment? With the Behringer ECM8000 mic.
From my understanding, for such a case, the ECM8000 would be good enough?
I also would rather spend money on upgrading the system and treating the room. A friend of mine already has the Behringer UMC202hd interface, so the total cost would be lowered.

Also considered the Dayton Audio iMM-6, but sounds it'd be worse than Behringer?
Unless it's absolutely necessary to get the UMIK-1 ...

For room treatments, having a way to measure impulse in real time is very valuable. You can see the squiggles in the impulse at later times, place a panel, and see if that spot eliminates those reflections the best.

So I'd 100% buy an xlr mic and interface. As long as they are well designed transparent devices, doesn't really matter which one you use.
The be ringer microphone is fine. I'm not sure on that interface though. It will most likely be fine.

Then use open sound meter to measure the impulse in real time, and your room treatments will be done well!

See this example of how to do it written by a friend.

tutorial: how to find and treat early first reflections

This tutorial was done in my home, but the same concepts can apply to a car. My home stereo is in an asymmetric room and I have problems with the left and right speakers sounding very different. This disrupts my stereo imaging, is very annoying, and cannot be fixed with DSP. So I examined...

www.caraudiojunkies.com

 

[CauliflowerEars]

For room treatments, having a way to measure impulse in real time is very valuable. You can see the squiggles in the impulse at later times, place a panel, and see if that spot eliminates those reflections the best.

So I'd 100% buy an xlr mic and interface. As long as they are well designed transparent devices, doesn't really matter which one you use.
The be ringer microphone is fine. I'm not sure on that interface though. It will most likely be fine.

Then use open sound meter to measure the impulse in real time, and your room treatments will be done well!

See this example of how to do it written by a friend.

tutorial: how to find and treat early first reflections

This tutorial was done in my home, but the same concepts can apply to a car. My home stereo is in an asymmetric room and I have problems with the left and right speakers sounding very different. This disrupts my stereo imaging, is very annoying, and cannot be fixed with DSP. So I examined...

www.caraudiojunkies.com

Oh, thank you! UMIK-1 gets mentioned so much, didn't know an XLR mic can have more functionality than the USB mic ...
From the tutorial you've linked: 'REW can certainly make these measurements, but if you are using an XLR microphone (not a USB one) and have a loop-back cable on your sound card, then you can do these measurements in real time' - by 'sound card', is he referring to the interface? Would any XLR-USB interface do the job or it also needs some more specific function/connection to have the 'loop-back cable'? (apologies, not yet sure what it is, but I guess I'd better make sure what to look for in the interface).

 

[Jdunk54nl]

Oh, thank you! UMIK-1 gets mentioned so much, didn't know an XLR mic can have more functionality than the USB mic ...
From the tutorial you've linked: 'REW can certainly make these measurements, but if you are using an XLR microphone (not a USB one) and have a loop-back cable on your sound card, then you can do these measurements in real time' - by 'sound card', is he referring to the interface? Would any XLR-USB interface do the job or it also needs some more specific function/connection to have the 'loop-back cable'? (apologies, not yet sure what it is, but I guess I'd better make sure what to look for in the interface).

Yes, soundcard = interface. It allows for audio out and microphone/audio in. You need both audio out and microphone in capabilities and this to be able to be sent to a computer.

Most microphone usb interfaces such as the motu m2/m4/etc, focusrite 2i2/4i2/etc, RME, etc allow for an "internal loopback" option to where the interface has a built in loopback. You can use a physical loopback too, just not needed anymore with the built in internal one.

 

[CauliflowerEars]

Yes, soundcard = interface. It allows for audio out and microphone/audio in. You need both audio out and microphone in capabilities and this to be able to be sent to a computer.

Most microphone usb interfaces such as the motu m2/m4/etc, focusrite 2i2/4i2/etc, RME, etc allow for an "internal loopback" option to where the interface has a built in loopback. You can use a physical loopback too, just not needed anymore with the built in internal one.

Thank you. So, would I basically just need to do the following?
1) With one cable (3.5mini jack - 6.3 jack) connect the 3.5 mini-jack headphone Output into a 6.3 Jack Input?
2) Then the XLR mic into the Line 1 Input.
3) USB into Laptop USB.

I guess, also turn the phantom power on. Not sure what the Line 2 switch do.
Just trying to make sure, if buying this interface would do the job.

https://www.amazon.com/M-Audio-M-Track-Solo-Interface-Podcasting/dp/B08Q1NJSBQ/ref=sr_1_1?crid=3QRZE09JXT2VG&keywords=m-audio%2Bm-track%2Bsolo&qid=1681233372&sprefix=%2Caps%2C452&sr=8-1&th=1

Gosh this audio love has some rabbit holes ...

 

[Jdunk54nl]

Thank you. So, would I basically just need to do the following?
1) With one cable (3.5mini jack - 6.3 jack) connect the 3.5 mini-jack headphone Output into a 6.3 Jack Input?
2) Then the XLR mic into the Line 1 Input.
3) USB into Laptop USB.

I guess, also turn the phantom power on. Not sure what the Line 2 switch do.
Just trying to make sure, if buying this interface would do the job.

https://www.amazon.com/M-Audio-M-Track-Solo-Interface-Podcasting/dp/B08Q1NJSBQ/ref=sr_1_1?crid=3QRZE09JXT2VG&keywords=m-audio%2Bm-track%2Bsolo&qid=1681233372&sprefix=%2Caps%2C452&sr=8-1&th=1

Gosh this audio love has some rabbit holes ...

That seems like it would work...not 100% sure if it has a good loopback option. You could go rca to trs in I suppose

There is also this one: https://store.focusrite.com/en-gb/p...Pc9Dh8fUuq4A_ikiavQodjoOROUh1rhRoCNxMQAvD_BwE

 

[CauliflowerEars]

That seems like it would work...not 100% sure if it has a good loopback option. You could go rca to trs in I suppose

There is also this one: https://store.focusrite.com/en-gb/p...Pc9Dh8fUuq4A_ikiavQodjoOROUh1rhRoCNxMQAvD_BwE

Thank you, it's a pity it's double the price here in Europe. I'm getting the interface just for the Behringer ECM8000 measurements (unless the Dayton Audio IMM-6 can be good enough ...).

Unless there is an audio interface that could rival the Topping E50 DAC, then maybe I could buy one device for both uses ...
But then, not sure if I could do the measurements with one device as an interface and output dac ...

 

[Jdunk54nl]

Thank you, it's a pity it's double the price here in Europe. I'm getting the interface just for the Behringer ECM8000 measurements (unless the Dayton Audio IMM-6 can be good enough ...).

Unless there is an audio interface that could rival the Topping E50 DAC, then maybe I could buy one device for both uses ...
But then, not sure if I could do the measurements with one device as an interface and output dac ...

Motu m2/m4 and focus rite are both rivaling the topping stuff. Measurements can be found here for them. Rme definitely rivals them.
I use my motu m4 as a dac a lot of times.

Motu M4 Audio Interface Review

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www.audiosciencereview.com

Focusrite Scarlett 2i2 Audio Interface Gen 3 Review

This is a review and detailed measurements of the Focusrite Scarlett 2i2 Audio Interface (DAC/ADC). I was talked into buying it recently. The 2i2 costs US $140 including free Prime shipping so very reasonable for amount of functionality. For a budge device, the Scarlett 2i2 looks pretty good...

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RME ADI-2 FS Version 2 DAC and Headphone Amp Review

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www.audiosciencereview.com

The imm6 will not be as good as an interface and xlr due to not being able to use open sound meter to its full potential.

 

[fluid]

Would a Behringer UMC202hd interface be good for amateur REW room measurements and treatment? With the Behringer ECM8000 mic.
From my understanding, for such a case, the ECM8000 would be good enough?

For any microphone to be of any real use in measuring the frequency response of anything, it needs to be calibrated or inherently accurate without calibration.
Nothing at a reasonable price is inherently accurate so calibration can fill that void. All of the cheap electret microphones have a similar frequency response but they vary enough for calibration to be necessary. Nothing else you do will matter as much as using an accurate mic. The differences between a cheap calibrated mic and a super expensive one only start to show when noise and distortion need to be really low.

The Behringer mic is fine if calibrated or you are lucky, for a little bit more money you can get a Sonarworks calibrated mic.

The Behringer interface is perfectly fine for acoustic measurements and is a good entry point, trying to save money below that level is where you will run into snags. The difference in measured response between most interfaces from the Behringer and above, that can be purchased now, is generally small and has no significant effect on what you will measure in a room. As you spend more money the mic preamps will get better and quieter, the convertors get better and the very low frequencies will tend to be more accurate. For in room measurements this will be hard to notice.

An analogue mic is the most flexible and a good investment but if money is super tight a UMIK on it's own will make very good in room measurements and be more accurate than a non calibrated mic and cheap interface.

Just be careful of trying to cheap out on tools and then end up spending more in the long term buying things twice or more.

 

[617]

I would highly recommend the motu m4. It is sort of a swiss army knife for getting audio into and out of computers, plus it has really nice meters (not just a clipping indicator.) It can drive largish headphones, the DAC and ADC are both great, and it has low latency.

It seamlessly controls my powered monitors, my microphones which I used to use for videoconferencing, my headphones and even some midi stuff.