Thanks so much, Stephen! I am working on part 2 right now.

@@MusicCityAcoustics Hello, I am trying to understand relation between audio interface calibration and usage of USB microphone like UMIK-1 from miniDSP. I mean what is calibrated during loop back procedure of the audio interface? Input or output? Seems to be too many variables in this equation. On top of this USB embeed ADC of microphone takes the role of interface input, correct? So in case of UMIK-1 is the audio interface calibration relevant and important?

@@wodzimierzwohn114 If you are using a USB microphone, you can skip the calibration process.

I'm so glad the video helped! REW can be a little daunting but it is a very useful tool once you break it down to the basics! Thanks so much for the comment. Cheers!

Hi Benny, you are so welcome! Thank you so much for watching and for the positive feedback. It makes all the work that goes into making the videos worth it!

You are very welcome, and thank you!!

Thanks so much for watching! I took all of the example measurements for Part 2 last week; I am working on the script this week, and will film part 2 next week so it should be here soon!

@@MusicCityAcoustics awesome news! I've already subscribed and selected all the notifications, buet its not working proppertly, so you should make a post on your latest video to make sure everybody knows there's a new one...

Hi Diego. You are very welcome. Thanks so much for watching!

Hi Edy, thanks so much for your comment. We'll be covering all of that and more in part two. I'll be showing measurements of a room with and without acoustic treatments, as well as how different speaker and treatment placements can affect things.

@@MusicCityAcoustics Cool TKS

You can’t. There’s nothing to show because every single microphone has its own frequency response curve that needs to be accounted for. If you can, I would look into saving up for Soundworks SoundID. It comes with a reference mic and the calibration file downloadable from their website. Then the added benefit of speaker EQ is worth its weight in gold.

You are very welcome! REW does have RTA functionality but I'm not super familiar with SMAART so unfortunately I can't compare the two. REW can certainly be used to measure large rooms and systems though.

I was also thinking why the heck does he need a spl meter for 😂 Good video nonetheless 😊

I'm working on it now. Hopefully we will have it ready to publish in 3 to 4 weeks!

@@MusicCityAcoustics LOVELY. I am ready with Behringer emc 8000 and UMC 404hd for the training

Hi Robert, we measure the left and right speakers independently because of the distortion that occurs when measuring the left and right speakers together. Measurement microphones are extremely sensitive (much more so than our ears), and as a result, if there is the slightest variation in distance from the microphone to the left or right speaker, this will show up on the measurement as a large drop off in your room's high-frequency response. It does not provide a realistic representation of what we would actually hear or perceive in the room. When analyzing lower frequencies, both speakers can be measured together, which is why a typical measurement set would include the Left, Right, and Left and right tests. I hope this helps. We have a Free Room Advice Form on our website that is a great way to get started if you want to get in touch with us. We don't offer free REW analysis as that is typically a pretty long and intensive process with lots of measurements to analyze,e but we'd love to talk with you more about your room and see how we can help! You can find the form here: www.musiccityacoustics.com/free-room-advice

Good point. Unfortunately our head and microphone can't occupy the same space so one of them has to move for measurements. I typically just moved away from the microphone as our bodies will have a significatnt impact on the high frequency response if we are close to the microphone, we have little to no effect on lower frequencies though. Leaving the room for our purposes is not super important but is the "technically correct" approach when testing room acoustics or gear.

Hey Drew, hopefully it will be ready to publish the week of April 11th!

You'll want to measure each speaker individually and the left and right speakers together. If you haven't checked out Part 2 yet, it breaks down in much more detail how to analyze the measurements! kzfaq.info/get/bejne/edt1qtKWs52-ep8.html

Hi! Thanks so much for watching. We calibrate the system so the output level of the speaker is 80dB at the location of the microphone. The actual speaker output will be higher than this. After calibrating the input of your measurement microphone to 80dB, if your room and speakers were perfectly flat, your measurement should be right around 80 dB. Of course, in all rooms, there is a lot of variation, so things will go above and below 80dB. Thanks for your question! -Graham

​@@MusicCityAcoustics If decide to go the MiniDSP USB measurement mic route as suggested on the REW website, do I need the standalone SPL meter at all? And since I will be using an Apollo x8p interface essentially only to drive the test tone to the speakers, am I going to need to do a sound card loop back calibration?

We used an xlr to trs cable but it will be unique to your interface.

Hi Evan, great question! Unlike most microphones used for recording that are designed to sound good or pleasing, measurement microphones are designed to have a flat frequency response to provide accurate feedback and measurements. There are two other main differences, one, they are omnidirectional, and two, they often have a calibration file that accounts for any variation in their frequency response. The cal file can be loaded into REW, so the microphone's frequency response is accounted for in your measurements. When looking at room acoustics, we are often looking at the room's low-frequency response. It is always ideal to use a measurement microphone for accurate results, but if the only mic you have is a cardioid condenser microphone, you can use it to get a better understanding of what is happening in your room. Just remember your measurements will also be showing your microphone's frequency response.

Hi! While filming this, I was monitoring the output of my interface on the left channel, so I could not use it or the calibration. The sound card calibration can be done with the left or right output. Interfaces should be identical, if not nearly identical, from channel to channel, so the left or right output won't have a significant effect here. I wasn't using the loopback functionality in the video, so those settings were just left on the default.

Same here. This guy doesn't do anything to help either.

It is always a good idea as there is a sound-card in your computer. If you can't get the calibration process to work, you can take measurements without doing it though. Most sound-cards have a very flat frequency response and if there are any variations in performance it typically is in higher frequencies and room measurements are primarily focused on analyzing mid and low frequencies.

@@MusicCityAcoustics I assume that it is not necessary to calibrate the sound card if you use a usb mic like UMIK. This is stated on the rew website "Calibrating the Interface This step is not applicable when using a USB microphone as the input, skip directly to Check levels"

@@franknielsen7597 yea that is correct!

Pros in studios don't even bother with them. Sometimes they're wrong to begin with-- you're better off just accepting any small deviation. Best chances are that it'll be the lesser of evils.

This would be awesome. The way it works now you really only have two options: 1--You buy a cheap USB microphone that comes with a compatible calibration file. Or 2--you buy a really expensive calibrated measurement microphone that is truly flat so you can use the default "flat" mic response in REW. Wouldn't it be nice to be able to use all of the mics and preamps that exist in the space between these 2 extremes?

@@guy48065 You can still definitely use any mic, but it's just not optimal I presume. Also, I'd only use a Non measurement Mic that is fairly flat, but you could use anything. I dunno if it would be possible to make a feature where the user loads in the Freq Response Curve, and also I don't know how accurate most of the general Response Curves are that the Company's release. They might not be in depth/accurate enough, Im not sure. I just thought, since you can technically you can use any Mic, that maybe loading a Factory FRC might get you a bit closer, or maybe EQ Wizard could start loading in Specs for different Studio Mics, but at the end of the day that's a lot of time/labour when the programs free, and people can access cheap Measurement Mics.

You want to measure with everything as it is with the microphone at your listening position. You want to measure the real sound not some best case scenario as you don't use the speakers in the best case scenario.

Thanks so much! Hopefully, I can help with your questions. 1. The loopback captures the interface's frequency response for calibration purposes. What we show in the video is to create the calibration file, not a timing reference. However, you can set up a timing reference for your measurements using this same loopback configuration on an interface with two or more inputs/outputs. This is particularly helpful and needed when analyzing phase and group delay 2. For the calibration loop back, I set the input to line level. If you try to run the calibration measurements with the input on your interface set to mic input instead of line level, it will distort. I believe that is what you are currently experiencing. I hope this helps!

@@MusicCityAcoustics You're amazing. I thought it was a line-in unless phantom power was on. But everything is so low - and REW asks for the levels to be raised. I'll check into the line level stuff. Cheers

@@dadell Thanks. I hope it works for you!

@@MusicCityAcoustics Wait, something doesn't make sense. If you're telling users to not use their microphone preamps while calibrating the interface, the coloration of the preamp will not be included in the calibration. That means, when you do use the preamp when measuring the room with your microphone, you will not be getting as accurate of a measurement. How does this make sense?

Type in "beyerdynamic mm1 calibration file" google, first page I found walks you through how get it. Cheers!

Not at all. Measure away!

Hello! You only need to take a measurement of the empty room and a measurement of the room furnished if you want to see what impact the furniture is having on the room. Otherwise, leave everything in there and measure away. Furniture and equipment will absolutely have an impact on your room's frequency response but assuming that it will be there when you are in the room listening, it can stay in the room for measurements.

@@MusicCityAcoustics you are the best!

Yes

I actually need this answer

It would be both as if you turned 1 speaker on and measured then turned the other on it would be around 6db louder

me too

You compensate for the speakers response by calibrating with pink noice with a mic that you know its linear or has a calibration file.

@@OlaJustin That only works in an anechoic chamber. To answer the original question: You use REW to measure the actual sound you hear. You want to make your room sound as good as possible with the speakers you have. If you change the speakers you want to re-measure, update your room acoustics if possible, and then tweak your EQ. However, most room acoustic problems you treat for are speaker agnostic. If you have a standing wave at 45Hz in your room it will not change with different speakers. If you have a reverbation peak, flutter echo, small listening postition, impropper projection or any other similar issues, then you don't realy care about the speakers and can make the adjustment with pretty mouch anything. Frequency response is pretty mouch the only outlier, but it also is the one thing that can be easily treated with just EQ.

Had the same problem. You can see under the "loopback input" there's an "Input volume", you can increase it by clicking the arrows. This will solve the problem. Sorry for my horrobile English :)

@@maayanbalmas8999 Oh! Is there something like that? Loopback volume? in Focusrite app? or REW?

I think we're on the same boat! My interface is a Scarlett 18i20 and it can only go up to -18db before the sound distorts due to the feedback. Even on such a low level, when I start the process of creating the calibration file, the program shows a warning that occured clipping! I don't know what to do...

Hi Ivan, the sound card calibration is created following the process shown in the video. If you are looking for your measurement microphone's calibration file, it can typically be downloaded from the manufacturer's website. It does vary a bit from company to company, though. I hope this helps!

Great questions! It's the same measurement but with octave band smoothing. In this case, 1/24th. You can see the settings applied to each measurement in the text box towards the bottom of the screen.

If you haven't tried turning up the speaker output, I would start there. If you have already been doing this, double-check the input settings on your interface and try the different options. I hope this helps!

Thanks for your question! On our website, we have a Free Room Advice form. You can include your measurements there as a zip file. www.musiccityacoustics.com/free-room-advice

If you have a USB microphone, you do not need any interface. An audio interface like our Duet is a digital-to-analog and analog-to-digital audio converter, and it has microphone preamps and monitor level control built into it. This is a very common set up for studios but not typically what you'd have in a dedicated listening room or home theatre.

Hi Ant, unfortunately, I am not familiar with the Pioneer mcacc so I am not sure if it works in the same way. Sorry, I can't provide more insight.

the principle is the same but i'm afraid you need an extra device to enable a close alignment between the subs: the MCACC can't set individual delay times for each sub, it will try to average all subs together and then try to match it w/ the rest of the speakers. you might get lucky so that all the subs work together or you'll need a device that allows you to control each sub's delay separately. considering the subs are different, their phase is not consistent even when the phase settings are identical on all 4. it's just the nature of each speaker in each cabinet. ps: if your subs have a variable phase setting, not just the 0-180 switch, there is a chance you could integrate them without the help of an extra DSP processor. i would start aligning the best sub w/ the speakers, and then using the first sub without the speakers start adding one sub at the time working the phase till a constructive interference is obtained. ps2: the crossover on the subs also has an effect on the phase alignment. let's say two subs work together well but the third one can't be integrated without degrading the SPL in the sense that on one phase setting it does well in the lower end but poorly on the higher end and on another phase setting vice-versa. adjusting the crossover on the sub may offer you enough of a phase shift to obtain an overall improvement. (crossover filters change the phase depending on the slope of the filter: a second order filter changes the phase 180 deg) hope this helps and good luck

Apart from the frequency response almost all the measurements are speaker agnostic. Your decay times, standing waves, etc. do not care what speakers you have. For example if your room has a standing wave at 50Hz and you speakers can reproduce 50Hz at all you will see a long decay time. no matter if the speaker produces it a few db quieter or louder. REW (as the name implies) is meant for measuring rooms. You have your speakers, you measure your room treat it and make it sound as good as possible through acoustic treatment and speaker positioning as well as EQ. When you change your speakers you do this again to get the most out of them. If you treated the room for some perfect speakers (0 distortion, perfectly flat from 10Hz to 20kHz with no phase shifts, basicaly what you would get if you had a calibration file for them.) and then plugged in REAL speakers it would sound bad. You want to measure the speakers you have, not the ones you dream you had. If you don't you just get a worse sounding result.

Hi Dennis, a body will have very little impact on the measurements at lower frequencies. With room measurements, this is primarily what we are looking at. At higher frequencies, any small movement of the microphone or objects/people will have a meaningful impact on the results. This is why it is important to stand away from the microphone or leave the room. Unfortunately, both your head and microphone can not occupy the exact same space but this does not make the measurements invalid.

I thought the same. How often do we use our speakers when we are not in the room? Our presence is a constant to me. Playing sound while not in the room seems pointless.

I'm in the room when I'm mixing so...

I always use the speaker signal for calibration unless I am only testing a sub. If testing a speaker and sub together, I would use the speaker calibration signal. Subwoofer levels are largely subjective unless you are aiming for a flat frequency response. As a result, calibrating to the sub and speaker level would be quite challenging. I hope this helps!

​@@MusicCityAcoustics Thanks for the reply. Just to be clear, do you mean that you don't recommend measuring speakers and sub simultaneously? Also, I would appreciate your answer to one further question: At 10:48, which of those output settings refers to the sub alone (I’m guessing it’s C or LFE)? And if I wanted to take a measurement of the speakers and sub simultaneously, which of those output settings would I use? There doesn’t seem to be an output setting for L+R+sub. Thanks

Use the speaker cal signal. When balancing subs and speakers, it is typically the sub-level that is adjusted. Because of this, we want to use the speaker level to calibrate the measurements. Then if more or less low-end energy is needed, the sub-level can be adjusted to provide the desired frequency response. I only use the sub cal signal when measuring subs by themselves.

@@MusicCityAcoustics Thanks but perhaps I wasn't clear on my last question. I understand that I should use the speaker cal signal but in my last question I was referring to which output to select. At 10:48 in your video, there are a list of outputs. Which one refers to the sub? And which output refers to the speakers + sub together? Thanks.

@@walshythemusician you absolutely should measure the sub and speakers together as well as measure them individually. In most studio setups, the output of the interface or monitor controller goes to the sub(s), and then from the sub, the L and R speakers are fed. This negates the need for a separate output from REW for the sub. If your sub is on a separate output from your interface, say 3, for example, then you'll need to look at using the C or LFE output, but I've never had to use them before.

Hi John, sorry it is giving you a hard time. In most cases, the soundcard's frequency response is nearly perfectly flat. I'm not sure what is going on with the 18i20 calibration, but you can skip this step if you can't get it working.

@@MusicCityAcoustics But if it is not flat, does this mean that there is something wrong with my audio interface?

mine looks terrible as well and its a UAD Apollo

Mine too, apollo twin has a big spike 97 Hz and pretty much all over the spectrum. The phase is just pretty much just a big band instead of being a line. Maybe the scale of the graph is different? My soundcard response from -90 to +39 SPL and the phase from -25 to +25.

I am experiencing the same problem. After connecting my input 1 to my output 1 my graph was showing a linear in stead of a flat horizontal line. I than did a calibration with my output 1 to my output 1 whilst also having connected my output 2 to my input 2 and the graph suddenly shows a flat line. No idea if this is a solution or if I'm doing something wrong with a lucky outcome.😂

Hey Travis! I'm not sure what the issue is with Apollos, but we've had a few people reach out to us with similar problems. My guess is it has to do with the UA software and internal routing, but I'm not sure. If you can't get it to work, you can take measurements without calibrating the interface. If you are designing pieces of hardware gear or building speakers, I wouldn't recommend this, but for room measurements where we are primarily concerned with the low-frequency response of the room, it is fine.

I found out that the buffer needed to be increased above the default 32 - I set it at 128 and it’s working 👍🏼 - thanks for the reply, great vids!

Hey! The Radio Shack meter should work great as an SPL meter for calibration. Set it to C weighted and slow if it has a speed option.

@@MusicCityAcoustics Thank you.👍🏽

You are very welcome! Thanks so much for watching. There are a few other options out there if you are interested. Fuzz Measure, and SMARRT for example REW is a very comprehensive option and best of all, it is free.

I had a 30 day trial Sonarworks SoundID and it is way easier to set up, although the software alone without the microphone will cost you 250$. It might be what you're looking for!

@@djahyeahh thanks let me give it a try

@@djahyeahh Sonarworks is definitely easier to set up but it doesn't tell you a whole lot about what is actually happening in your room. In how to use REW part 2 I break down how to analyze the various types of measurements and graphs in REW that allow us to really understand what is happening acoustically in a room. Sonarworks is an awesome tool for quick, easy, and affordable room eq though.