You are here

DIY Speaker Frequency Testing Methods

Customising, building or repairing your own gear? Need help with acoustic treatment or soundproofing? Ask away…

Re: DIY Speaker Frequency Testing Methods

Postby pkalder » Wed Feb 06, 2019 3:25 am

Does anyone know what the cheapest calibrated mic is?

Well this will muddy the thread up with cheap solutions. I got the Dayton imm-6 calibrated which a reviewer compared to the umik-1 and got a +-1 db difference up to 17khz. Doesn't seem too bad for a $20 dollar mic and its own calibration file.
pkalder
New here
Posts: 9
Joined: Wed Jan 23, 2019 5:00 pm

Re: DIY Speaker Frequency Testing Methods

Postby Martin Walker » Wed Feb 06, 2019 12:18 pm

Hugh Robjohns wrote:if you can acquire a proper calibration chart/file it's inherent production tolerance variations can be compensated given the appropriate measurement software.

I've just put my money where my mouth is in this regard, and ordered a Sonarworks XREF20 measurement microphone - once again a budget model, but each one given its own serial number and frequency response individually measured to high accuracy. You just enter the serial number on the Sonarworks web page and get your personalised calibration file:

https://store.sonarworks.com/products/m ... ng-studios


Martin
User avatar
Martin Walker
Moderator
Posts: 14028
Joined: Wed Jan 13, 2010 9:44 am
Location: Cornwall, UK

Re: DIY Speaker Frequency Testing Methods

Postby OK1 » Wed Feb 06, 2019 1:11 pm

wireman wrote:Does anyone know what the cheapest calibrated mic is? I was thinking of getting the UMIK-1 next time I'm in the USA. Don't really have a serious application but I'm interested in the frequency response of a few locations.

Pretty certain it's the Dayton Audio EMM-6 for best price calibrated microphone, for your purpose.

I have been using the Dayton Audio EMM-6 which comes with a unique serial number (you must be careful cos this serial number is easily erased by rubbing or solvents such as hand cream) so advise that you copy the serial number and store in a safe place, that you can use to download the associated calibration file, from their website.

Bought in 2016 from Soundimports.nl which is now soundimports.eu (based in the Netherlands).

https://www.soundimports.eu/en/test-measurement/

Pretty certain there are now some places in the UK IIRC where you may purchase one, please google.

Here you go

https://wallofsound.co.uk/p-category/test-equipment/

One challenge is learning how to use these calibration files in your software, I use REW(Room Equalisation Wizard) for measurement. Some editing of the file is needed for the calibration file provided by Dayton Audio.

The EMM-6 ideally requires that you obtain a secondary device, an SPL meter, if you wish to be precise about the levels at which measurement is done, in REW. EMM-6 is an electret capacitor(condenser) microphone and needs phantom power from your audio interface. An SPL Meter is nevertheless a good thing to have if you are "serious" about your audio. google(search) SoundonSound for Hugh's recommendations on SPL meters.

I understand that the USB versions of Dayton Audio measurement microphones (which I have no experience with) work with REW in a slightly different way, and in addition to calibration, they have some way of interacting with the software, to omit this need for an SPL meter. It's all explained on the REW site.

Just to be clear, depending on your measurement position - and distance from the speakers, these tools (REW and the measurement microphone) provide a decent enough view of your speakers frequency response (as measured), and interesting waterfall plots of the decay of each frequency. And some of this can be done in real time IIRC, so you can adjust things on your speaker or room acoustic treatment and see the impact (you should wear some earplugs while doing this in real time, to remain sane and not damage your hearing).

While all manner of arguments can be made for the effectiveness or otherwise of these cheaper/free solutions, and the impact of the non-anechoic environment in which the measurements are obtained, if you take a few measurements from slightly different positions in your room, hopefully not too far from each other, you get a really good sense of how one speaker compares with another speaker, or how tone control adjustments on an active speaker affect frequency... definitely an education, makes you more appreciative of what's going on, at a basic level, in the frequency and time domain.

Unfortunately it opens a can of worms - a whole universe of information/curiosity that takes you down lots of rabbit holes, settings, time windows, phase, etc, and an effort to make sense of it all. Depends on what you want to achieve.
OK1
Regular
Posts: 80
Joined: Sun Sep 27, 2009 12:00 am
Location: Reading, Berkshire, UK

Re: DIY Speaker Frequency Testing Methods

Postby OK1 » Wed Feb 06, 2019 1:21 pm

Depending on exchange rates, the Sonarworks measurement microphone suggested by Martin, may be slightly cheaper than the Dayton Audio EMM-6 I had suggested - but we're talking small change differentials - a few pounds give or take.

The key issue is being able to use the format of the calibration file in your software. So do research this before purchase, check with Sonarworks/Dayton Audio + google.
OK1
Regular
Posts: 80
Joined: Sun Sep 27, 2009 12:00 am
Location: Reading, Berkshire, UK

Re: DIY Speaker Frequency Testing Methods

Postby Martin Walker » Wed Feb 06, 2019 2:18 pm

OK1 wrote:Depending on exchange rates, the Sonarworks measurement microphone suggested by Martin, may be slightly cheaper than the Dayton Audio EMM-6 I had suggested - but we're talking small change differentials - a few pounds give or take.

You can get significant price reductions on the Sonarworks XREF20 if you shop around - I ordered mine from here:

https://www.dv247.com/en_GB/GBP/SONARWO ... 014332-000

A bargain at £49.90 + £4.99 P&P!! :o


Martin
User avatar
Martin Walker
Moderator
Posts: 14028
Joined: Wed Jan 13, 2010 9:44 am
Location: Cornwall, UK

Re: DIY Speaker Frequency Testing Methods

Postby OK1 » Wed Feb 06, 2019 2:36 pm

Martin Walker wrote:
OK1 wrote:Depending on exchange rates, the Sonarworks measurement microphone suggested by Martin, may be slightly cheaper than the Dayton Audio EMM-6 I had suggested - but we're talking small change differentials - a few pounds give or take.

You can get significant price reductions on the Sonarworks XREF20 if you shop around - I ordered mine from here:

https://www.dv247.com/en_GB/GBP/SONARWO ... 014332-000

A bargain at £49.90 + £4.99 P&P!! :o


Martin

Wow - did not know that the Sonarworks mic was available elsewhere, a significant discount on the cost from Sonarworks site! Good to know. £55 for a calibrated mic....including shipping....

Checked the assumed calibration file format for Sonarworks microphone, I am pretty certain, it should also be usable in REW.

https://sonarworks.zendesk.com/hc/en-us ... tion-file-
OK1
Regular
Posts: 80
Joined: Sun Sep 27, 2009 12:00 am
Location: Reading, Berkshire, UK

Re: DIY Speaker Frequency Testing Methods

Postby wireman » Wed Feb 06, 2019 6:29 pm

OK1 wrote:I understand that the USB versions of Dayton Audio measurement microphones (which I have no experience with) work with REW in a slightly different way, and in addition to calibration, they have some way of interacting with the software, to omit this need for an SPL meter. It's all explained on the REW site..

When I first thought about getting a measurement microphone I just assumed that for a USB mic because the output is digital it can be calibrated against sound pressure directly. For an analogue mic there is no way you can do this as you would need to map the microphone voltage output to the digital value. Hence you need some external SPL measurement(s) if you care about absolute values.
wireman
Regular
Posts: 267
Joined: Fri Dec 17, 2004 1:00 am

Re: DIY Speaker Frequency Testing Methods

Postby Martin Walker » Wed Feb 06, 2019 9:28 pm

OK1 wrote:
Martin Walker wrote:You can get significant price reductions on the Sonarworks XREF20 if you shop around - I ordered mine from here:

https://www.dv247.com/en_GB/GBP/SONARWO ... 014332-000

A bargain at £49.90 + £4.99 P&P!! :o

Wow - did not know that the Sonarworks mic was available elsewhere, a significant discount on the cost from Sonarworks site! Good to know. £55 for a calibrated mic....including shipping....

Checked the assumed calibration file format for Sonarworks microphone, I am pretty certain, it should also be usable in REW.

https://sonarworks.zendesk.com/hc/en-us ... tion-file-

Yes, I've already entered a couple of 'dummy serial numbers' so I could download two XREF20 calibration files, and they are in standard .txt format that you could load into Room Eq Wizard and the like.


Martin
User avatar
Martin Walker
Moderator
Posts: 14028
Joined: Wed Jan 13, 2010 9:44 am
Location: Cornwall, UK

Sonarworks XREF20 measurement mic - calibration

Postby Martin Walker » Fri Feb 08, 2019 1:57 pm

Right - my Sonarworks XREF20 measurement mic has just arrived, and entering its unique serial number into the Reference 4 Measure app immediately gave me very healthy looking on-screen calibration, with essentially a smooth rise above 1kHz, maxing out at around 2dB @8kHz and again somewhat higher:

MW-XREF20.jpg


Now it's time to run all my room measurements again, to see just how different they are from those made with my heavily-modded Tandy SPL meter (all the caps increased in value to greatly extend low end response, and halving the opamp compensation cap to hopefully provide a rather increased high end response).


Martin
User avatar
Martin Walker
Moderator
Posts: 14028
Joined: Wed Jan 13, 2010 9:44 am
Location: Cornwall, UK

Sonarworks XREF20 measurement mic - studio results

Postby Martin Walker » Fri Feb 08, 2019 2:33 pm

Well that was indeed an eye opener - here are the measured room responses measured first by my analogue Tandy SPL meter:

MW-TANDY.jpg


...and then by the Sonarworks XREF20 measurement microphone:

MW-XREF20.jpg


As you can see, both are in the same ballpark, and my low end mods worked well, extending the Tandy meter with a couple of dB of the XREF20. The rest of each curve up to around 2kHz is quite similar, showing the difference between left and right channels (I have a large window on one side of my studio, which disturbs its acoustic symmetry).

However, above 2kHz the measurement difference between the two mics is huge, which proves that unless you have a proper calibrated mic you can end up making wrong decisions about your acoustics.

I already suspected that the Tandy response was falling rapidly above 10kHz, so had already limited its Sonarworks correction curve to ignore this anomaly. Nevertheless, I was surprised that the Tandy mic had such a large (and now obvious) low Q bell curve between 2kHz and 8kHz, peaking at around +4dB at 5kHz, and am far happier with the correction curve of the accurately calibrated Sonarworks XREF20 mic, showing my little studio was already reassuringly flat above 2kHz.

Here's the final correction curve (green, for both L and R channels) for my studio, along with the simulated 'after' response (blue) from Sonarworks:

MW-XREF20correction.jpg


The top end now sounds beautifully silky and flat, while the lows are now extended to -3dB @37Hz (pretty good for my tiny ATC SCM10 loudspeakers - I could switch to a flat response down to -1dB @27Hz by changing to the Sonarworks Aggressive low end response, but that would require up to 9dB boost at 20Hz, and I really don't think the extra 10Hz of low end would benefit my music or the longevity of my monitor speakers).

However, the most remarkable improvement is that my stereo imaging is for the first time razor sharp.

The Reference 4 software is simplicity itself to use, and with my trusty old Tandy SPL meter had already sorted out my low end anomalies, but switching to the XREF20 mic gave me improvements in high end smoothness and stereo imaging that were nothing short of remarkable.

I can heartily recommend the Sonarworks XREF20 mic, as well as the Sonarworks Reference 4 Measure software. Result! :clap: 8-) :thumbup:

Now I need to go off and revisit my recent mixes to make some tweaks :beamup:


Martin
User avatar
Martin Walker
Moderator
Posts: 14028
Joined: Wed Jan 13, 2010 9:44 am
Location: Cornwall, UK

Re: DIY Speaker Frequency Testing Methods

Postby OK1 » Fri Feb 08, 2019 11:32 pm

Sonarworks and the users who have responded to their compelling value proposition, must be congratulated.

A great product and business that's gone from strength to strength.
OK1
Regular
Posts: 80
Joined: Sun Sep 27, 2009 12:00 am
Location: Reading, Berkshire, UK

Previous

Who is online

Users browsing this forum: No registered users