Microphone for Acourate

[kilroy]

I’m looking for a bit of help as to how to get started taking measurements using the Acourate program. I have not purchased the software yet, but like the fact that there are some detailed instructions and even an eBook (thanks to mitchco) on creating the filters, which I would like to try in JRiver. Specifically, some guidance on the microphone connections would be appreciated.

 

I had previously experimented with the Dirac trial version, and purchased the recommended calibrated USB mic that plugged directly in to my then laptop server. I did not end up purchasing Dirac. Now however after further researching available programs I’d like to try Acourate. Mitch’s eBook states that USB mics are not the best suited for this application so I’m looking at other mic options.

 

In Mitch’s article on CA he references the “MP-1r-KIT Acoustical measurement kit” available from Isemcon; however Wolfgang from Isemcon advises that this kit has been discontinued and replaced with the “EMX-7150 Phantom powered microphone”. This mic does not appear to have a preamp. Also it comes with Neutrik connectors.

 

How would this mic be connected? My present setup is this:

 

Dedicated Windows server, USB out to an Auralic Vega DAC, RCA out from DAC to the system preamp.

 

Would this mic work in this setup? Note the server does not have a separate sound card. Are there other options for mics or connectivity? And as I do have the MiniDSP UMIK-1 USB mic from Cross Spectrum labs (with a calibration file), is using this mic not recommended at all?

 

Thanks for any help.

[Keith_W]

Hello kilroy. If you are in Australia I will be selling my old measurement setup next week because my new gear will be arriving. These are the usual microphones that people use with Acourate:

 

- Dayton EMM-6 calibrated

- Behringer ECM8000 (make sure you buy one that is individually calibrated. From the factory, ECM8000's are NOT calibrated, but you can buy calibrated ECM8000's from third parties)

- Earthworks M23, M30, or M50

 

Apart from the Earthworks, the above microphones are reasonably priced. All require 48V phantom power, meaning you need a mic preamp.

 

I recommend that you buy a USB sound card which has AD/DA conversion and a built in mic preamp, such as one of these:

 

- Focusrite 2i2 or 6i6 (depending if you need the extra features of the 6i6)

- RME Fireface UC (this is what I use)

- Lynx Hilo (used my Mitchco)

 

In addition, you will need these cables/accessories:

 

- A USB cable which is long enough to run from your PC to your sound card,

- Pro audio cards usually output via TRS sockets, either balanced or unbalanced. You will need a cable with TRS on one end, and RCA or XLR on the other (depending on the type of input your preamp uses)

- a sufficiently long microphone cable. Just buy a cheap XLR cable from a pro audio shop.

- a microphone tripod. Acourate's mic alignment procedure depends on you being able to consistently locate your mic at your listening position, and the only way to do this properly is with a mic tripod. Don't worry, these are cheap.

 

I can tell you that the author of Acourate, Uli, uses an Earthworks M50 and an RME Fireface UC himself. I know, because I asked him

[Keith_W]

Oops, I missed your question on how to connect the measurement setup. Essentially, you remove your Auralic Vega and put the USB card/mic preamp there instead. Assuming you are using a Focusrite 2i2:

 

PC --(via USB)--> 2i2 --(cable TRS on one end, RCA on the other)--> preamp

 

As for your UMIK-1, yes you can use it. But you would want to get it calibrated first. Type "microphone calibration service" into Google and find the nearest one. You normally have to mail it to them and they mail it back.

[kilroy]

Hi Keith, thanks for that comprehensive reply. I am in the US so likely not practical to take those items off your hands.

 

Sounds like you've been through this so can I ask a few questions, still about mic hookup. Bear in mind I'm a novice in the use of this equipment.

 

From what I can figure, the mic would plug into the USB sound card (which is actually an external box, a surprise to me), say the Focusrite 212 which is reasonably priced. The sound card is connected via USB to the computer/server, which has the Acourate program installed. There are additional outputs from the sound card to the preamp.

 

So start up Acourate in the computer, generate the test signals from this computer, out through my DAC/preamp/amp and to the speakers, picked up by the mic and then fed back into the sound card and computer.

 

Does that sound right?

 

Thanks again for the help.

[kilroy]

Keith, looks like our messages crossed. Got it, and thanks.

 

As for my UMIK mic, mitchco makes a remark in his ebook about USB mics not preferred (don't have it handy to check exact words). I'd prefer the best reasonably priced mic, even if it's not the UMIK, say the Behringer or Dayton.

 

If I did use the UMIK, then the preamp would not be needed, and just connect it directly into the computer, and leave the DAC in the system, correct?

 

Thanks again.

[mansr]

Keith, looks like our messages crossed. Got it, and thanks.

 

As for my UMIK mic, mitchco makes a remark in his ebook about USB mics not preferred (don't have it handy to check exact words). I'd prefer the best reasonably priced mic, even if it's not the UMIK, say the Behringer or Dayton.

 

If I did use the UMIK, then the preamp would not be needed, and just connect it directly into the computer, and leave the DAC in the system, correct?

 

Thanks again.

A USB microphone has a built-in pre-amp and DAC that is unlikely to be as good as a separate device. For room correction purposes it's probably still plenty good enough, certainly enough for trying out a correction system to get a feel for what it can do, even if a superior setup might give even better results.

[Keith_W]

Hi kilroy, the answer is "yes, you are correct" to both your follow-up posts. I personally don't see the point of a USB mic because you will need the sound card to generate the log sweep anyway. Motherboard sound is horrendously nonlinear and not suitable for generating log sweeps for measurement purposes.

 

I hope you enjoy Acourate. I can tell you that - of the thousands of dollars I have spent on my system, none have made as dramatic a difference as Acourate. Short of buying new speakers.

[mansr]

Hi kilroy, the answer is "yes, you are correct" to both your follow-up posts. I personally don't see the point of a USB mic because you will need the sound card to generate the log sweep anyway. Motherboard sound is horrendously nonlinear and not suitable for generating log sweeps for measurement purposes.

 

Why would you use the on-board sound card for the test signals? Naturally, the same DAC used for music playback should also be used for measurements.

[kilroy]

Why would you use the on-board sound card for the test signals? Naturally, the same DAC used for music playback should also be used for measurements.

 

Hi kilroy, the answer is "yes, you are correct" to both your follow-up posts. I personally don't see the point of a USB mic because you will need the sound card to generate the log sweep anyway. Motherboard sound is horrendously nonlinear and not suitable for generating log sweeps for measurement purposes.

 

I hope you enjoy Acourate. I can tell you that - of the thousands of dollars I have spent on my system, none have made as dramatic a difference as Acourate. Short of buying new speakers.

 

I do look forward to using Acourate. Although I'm a bit confused by the test signal thing. The server motherboard's audio is not activated and will not be. So I hope just using the DAC for now will work. When I used the Dirac trial with a USB mic on an earlier server that onboard soundcard was not used either but the DAC showed up and I used that. My intention might be just to try the USB mic anyway to start playing with the program, then invest in a better mic and external sound card once I have the software down pat.

[kilroy]

I've installed Acourate and am just using a USB mic for now to get a feel for the app. Got a couple issues.

 

In the ASIO Sweep Recorder dialogue when I select my Auralic Vega DAC driver, it says there are no input channels available. And there is nothing at all in the Output Channel boxes.

 

I also have ASIO4All installed, when selected it does see the microphone, and in Output Channels the only choice is HD Audio output 1 & 2. However, when Start Recording is selected, the process begins but there is no sound output.

 

Setup is a temporary laptop with Acourate installed, in place of my server, with the USB mic in a USB 2.0 port. USB out to the DAC. No other changes to the system.

 

I sent an email to Uli but it's the weekend so wondering if anyone here has any ideas.

 

This post is buried under a microphone topic so I might create a separate topic if no answers here.

 

Thanks.

[Keith_W]

kilroy, that is the problem with using your DAC for output and a USB microphone. Acourate does not allow you to use one ASIO device for output, and another ASIO device for input. The reason is because they want to force you to use the same device, so that output and input are tied together to the same word clock.

 

It IS possible to use a USB mic with a DAC, however. You need an ASIO bridge like VB Cable (which routes sound from one real or virtual input to another real or virtual input). So, output from Acourate goes to your bridge, and is routed to your DAC. Input from the microphone goes to the bridge, and is routed to Acourate. I have to warn you - there IS latency involved, and it MAY mean that the results of your log sweep are uninterpretable.

 

I can not give you any further advice on this, because I myself am struggling to get VB Cable to work.

 

By far the best solution is what I suggested. An outboard sound card / mic preamp / 48V Phantom power / ADDA like the Focusrite 2i2, and one of those microphones. I can guarantee you that this works, because I (and many others) have this exact same setup and it works.

[kilroy]

kilroy, that is the problem with using your DAC for output and a USB microphone. Acourate does not allow you to use one ASIO device for output, and another ASIO device for input. The reason is because they want to force you to use the same device, so that output and input are tied together to the same word clock.

 

It IS possible to use a USB mic with a DAC, however. You need an ASIO bridge like VB Cable (which routes sound from one real or virtual input to another real or virtual input). So, output from Acourate goes to your bridge, and is routed to your DAC. Input from the microphone goes to the bridge, and is routed to Acourate. I have to warn you - there IS latency involved, and it MAY mean that the results of your log sweep are uninterpretable.

 

I can not give you any further advice on this, because I myself am struggling to get VB Cable to work.

 

By far the best solution is what I suggested. An outboard sound card / mic preamp / 48V Phantom power / ADDA like the Focusrite 2i2, and one of those microphones. I can guarantee you that this works, because I (and many others) have this exact same setup and it works.

 

Keith, once again you're saving me on this. Many thanks. If you can't get VB Cable working then I'm not going to try, and it sounds like less than ideal anyway.

 

Looks like I'll be purchasing the hardware you mention.

 

Thanks again.

[Keith_W]

You are most welcome. I should point out that VB Cable is free (donationware) so you can download it and try it with no cost to yourself. If you can get it to work, please drop me a message because I am struggling through the rather unhelpful manual and the interface. Good luck.

[SwissBear]

Hi Keith,

 

Jumping in on this subject.

 

You are mentioning the Focusrite 2i2 as an option for external USB card. Isn't this device limited in bandwidth to 20Hz-20kHz ? Wouldn't it be worth buying a device which has a larger bandwidth and make measurements at 96kHz for better results in the high frequency range ?

 

Thanks.

[Keith_W]

Hi Swissbear, unless you own a tweeter and microphone which can output/record at 96kHz there is no point buying a device which is able to output 96kHz. FWIW I have just ordered an Earthworks M30 microphone, which is calibrated to be linear up to 30kHz. My sound card (RME Fireface) is able to output and record more than 96kHz. My Acapella plasma tweeters are able to go up to 40kHz.

 

But to be honest with you, I don't think I can hear anything above 20kHz.

 

At Acourate's recommended 48k sampling rate, the maximum frequency that can be sampled is 24kHz. Of course, you could use their 192k sampling rate, which allows frequencies up to 96kHz to be sampled. I don't see the point, though.

[SwissBear]

Hi Keith,

 

Thanks for the answer. I was probably not precise enough. I meant using a 96kHz sampling rate, in order to capture whatever was in the 20-25kHz frequency area, and which might be altered when measuring with a 48kHz sampling rate.

Thanks for detailing your measurement setting.

[kilroy]

Gentlemen, for kicks I've looked at units online going for up to $300 US, including the Steinberg and Native Instruments. I don't mind spending more if the results will substantially benefit my use. Just an fyi, but again, I'm far from an expert in these matters.

 

Thanks.

[Keith_W]

You haven't told us what is in the rest of your system, and whether you have any plans for upgrading. For example, if you plan to take full use of Acourate and use it to generate crossovers for an active system, you should buy a multichannel DAC like the RME Fireface UC. This is the route I went down - Acourate generates the filters, I load them into HQPlayer, and from HQPlayer I get 8 channels of sound going to a Merging NADAC MC-8, and from there into 8 channels of power amplification, and then into each speaker driver.

 

Swissbear, if you wish to take measurements at 20-25kHz then you will need a "better" sound card than the Focusrite 2i2. You are right, if you wish to sample at a higher frequency you will need a sound card that can accept input at higher sampling rates and is capable of generating higher frequencies. I am not going to get into a debate into whether it is audible or not. IMHO it is not audible. But if that is your wish, then i'm not going to try to stop you

[kilroy]

Keith, my needs are simple, just a good sound card to generate a sweep for a 2-channel system. No plans for crossovers or anything else. From a system standpoint the only caveat, for what it's worth, is it is a fairly resolving system. I'm sure my hearing most assuredly does not extend to 20 khz.

 

BTW I've contacted Cross Spectrum in the US about a calibrated Dayton EMM-6 mic. They're really vague on when and if they can ship so if anyone knows another source it would be much appreciated. Thanks.

[mansr]

Gentlemen, for kicks I've looked at units online going for up to $300 US, including the Steinberg and Native Instruments. I don't mind spending more if the results will substantially benefit my use. Just an fyi, but again, I'm far from an expert in these matters.

 

Thanks.

I have a Steinberg UR242, and it has the worst clock jitter I've ever seen. Probably not audible in most cases, and almost certainly not much of an issue for room measurements. It does make it mostly useless for accurate low-level measurements (which admittedly isn't its intended purpose). Just thought I'd mention it.

[Keith_W]

I have a Steinberg UR242, and it has the worst clock jitter I've ever seen.

 

Out of curiosity, how do you know this? Are you able to measure jitter? If so, please share. I am curious about what setup you would need to measure this.

[mansr]

Out of curiosity, how do you know this? Are you able to measure jitter? If so, please share. I am curious about what setup you would need to measure this.

 

I noticed something was off when playing or recording some test tones. Checking the clock input to the ADC/DAC chips with an oscilloscope shows the jitter clearly.

 

This is the clock waveform:

 

Now with a delayed sweep of 20.83 microseconds (one sample period at 48 kHz):

 

That's what jitter looks like.

 

This is a spectrum plot of the Steinberg playing a 10 kHz tone recorded on a Tascam UH-7000 (a much nicer device but about 3x more expensive):

 

Pretty nasty-looking.

[romaz]

kilroy

, I'm assuming you've heard back from Uli by now. He is very responsive. Uli sells his own microphone that already comes calibrated for Acourate for only 83.19 Euros. As for a list of sound cards that will work, this is what he suggests:

 

Steinberg UR12 or UR22

Roland UA22

Focusrite Scarlett 2i2

For a more professional soundcard, he suggests the RMW Fireface UC.

 

All of the above are equipped with a mic preamp and supply phantom power.

 

For the price of his software, he will assist you with making measurements and filter calculation via TeamViewer.

[kilroy]

kilroy

, I'm assuming you've heard back from Uli by now. He is very responsive. Uli sells his own microphone that already comes calibrated for Acourate for only 83.19 Euros. As for a list of sound cards that will work, this is what he suggests:

 

Steinberg UR12 or UR22

Roland UA22

Focusrite Scarlett 2i2

For a more professional soundcard, he suggests the RMW Fireface UC.

 

All of the above are equipped with a mic preamp and supply phantom power.

 

For the price of his software, he will assist you with making measurements and filter calculation via TeamViewer.

 

Heard back from Uli. He was able to tell me how to setup the USB mic with Acourate. Haven't had the time but might play with this. I still want to get the other mic and sound card for serious measurements. Thanks for this list of cards.

[edn4x4]

Heard back from Uli. He was able to tell me how to setup the USB mic with Acourate.

 

Care to share?

 

I am also looking into Acourate in my setup. Right now i have the UMIK USB. I would buy a non-usb from cross spectrum when they get them in stock - they currently show out of stock still.

 

Also,

Would this work for a pre:

https://www.amazon.com/Focusrite-Scarlett-Audio-Interface-Tools/dp/B01E6T56CM/ref=sr_1_1?s=musical-instruments&ie=UTF8&qid=1473695098&sr=1-1&keywords=focusrite+scarlett+solo