Please read FAQ before…




About this website

  • very complete for professionals but simple enough for amateurs !
  • a procedure that avoids mistakes to obtain valid graphs and easy to compare to others
  • MMM measurement is completed with other signals to check amplitude but also phases
  • the MMM method gives results nearer to what is really perceived than other methods
  • the target correction is automatically processed from your measurement
  • target can be finely adjusted
  • FIR correction is calculated for the processor or software you are using
  • this is the only method that is optimised for separated channels but also for channels driven simultaneously : this is much better in low frequencies
  • a full report is available in .png pictures
  • with a unique sound file, a full set of analysis and graphs is calculated and gives a very complete view to understand the room and loudspeakers and their interaction, and a good base to calculate corrections to better your listening experience
  • getting same graphs give the possibility to easily compare different setups
  • extensions to 5.1, 7.1, 9.1.4, 22.2, Atmos,… systems will come, including DCP sound files
  • you may even use your phone and mic for the recording

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Read the procedure before jumping on measurements ;)

Hereunder is a description of the whole procedure and you should find more detailed infos in all FAQ topics.

Unique advantages of this method

  • very complete for professionals but simple enough for amateurs !
  • a procedure that avoids mistakes to obtain valid graphs and easy to compare to others systems
  • MMM measurement is completed with other signals to check amplitude but also time and phase responses
  • MMM method gives results nearer to perception than other methods
  • the target correction is automatically calculated from your measurements and own datas
  • target can be finely adjusted
  • FIR correction is calculated for the processor or software you are using
  • this is the only method that is optimised for separated channels but also for channels driven simultaneously, much better for low frequencies
  • a full report is available in .png pictures
  • with a unique sound file, a full set of analysis and graphs is calculated and gives a very complete view to understand the room and loudspeakers and their interaction, and a good base to calculate corrections to better your listening experience
  • getting same graphs give the possibility to easily compare different setups
  • extensions to 5.1, 7.1, 9.1.4, 22.2, Atmos,… systems will come, including DCP sound files
  • you may even use your phone and mic to do the record

Procedure

You can visualise measurements without login. To access to menus “My profile”, “Upload recording” and “My files”, you have to register and reply to registration mail.

When registering, a field “Company or Title” will be the main folder for all your measurements, and images  and subdirectories by dates. Please note that the field “Company or title”, can only be related to one user and cannot be used later by another user (unless they are from same company, then please ask us). You cannot use a company name for which you have no rights. Accepted are alphabets, numbers, underscore “_” and spaces (but no space at beginning or end and no consecutive spaces).

Page “Upload recording”

  • Download stéréo wav file LA2v1
  • This file can be written on a CD or DVD or streamed by a computer or added to a DAW session (Protools, Nuendo, Pyramix,…)
  • Play the file in stereo on your loudspeakers and record simultaneously with your microphone.
  • You may record directly to your computer combined to  a measurement mic, using the record function on page “Upload my record” or upload a recording done by other means.
  • Record in uncompressed format .wav mono, 16bits or 24 bits, 44.1 or 48kHz (aiff or flac will be accepted later)
  • start recording and then playing just after : there is a 5s starting silence so you have time to get to the listening position
  • kplace mic at listening position : sine sweeps and sync bongs. Sweep signal is a sine signal which frequency is changing from very low to highest frequencies
  • voice «move mic to left » : place the mic about 30cm left to listening position, sweep on left, sweep on right
  • «move mic to right » : place the mic about 30cm right to LP, sweep on left, sweep on right
  • «slowly move mic » : slowly move mic in a volume of about 1 cubic meter around main listening place : pink noise 20s on left channel, 20s on right channel, 20s of correlated noise on both channels. In larger rooms, you can move mic in a larger volume  : 1/5th of each dimension is a guideline.
  • If you have a calibration file, send it together with the recording in the version corresponding to your use (ie version at 90° if mic was used vertically, as recommended).

Important :

  • sound level must be high enough, ie the voice level should be comparable to someone speaking in the room, also avoid any clipping on the recording
  • notice that we have no responsibility due to too high levels : start with low levels
  • record without filter, compression or any process or EQ (unless you do a measurement with correction EQ)
  • the recommended mic is MiniDSP Umik, at a resonnable price under 100€, connected in usb so you need no preamp. This mic is delivered with an individual calibration file at 0 and 90° : https://www.minidsp.com/products/acoustic-measurement/umik-1 or http://www.audiophonics.fr/fr/micros-de-mesure/minidsp-umik1-micro-mesure-usb-omnidirectionnel-p-8269.html or https://www.amazon.com/miniDSP-UMIK-1-Measurement-Calibrated-Microphone/dp/B00N4Q25R8
  • keep the mic vertically , pointing to ceiling, with the hand low on mic. Note that you have to send the corresponding calibration file (ie the one for 90°)
  • for left, right, front and rear position, better change slightly mic height
  • while sweeps, distance between positions is about 30cm for a studio or listening room and about 1m for a theater or large mixing room
  • with pink noise, the volume scanned by the mic is about 1mx1mx0.5m (Lxlxh) for a listening room or a studio up to 3mx3mx1m for a large room (preferably use a mic boom)
  • avoid any obstacle between loudspeaker and mic when moving mic
  • correlated pink noise is identical on both channels
    don’t move mic less than 30cm of obstacles (seat, table, console,…)
  • while moving mic, take care to constantly vary distance between mic and your body
  • the way to move mic is not very important but allways move slowly to avoid noises, ie 30cm/second
  • the whole stereo sequence is about 2mn 30 seconds
  • synchronisation is automatically done by software : no need to precisely cut the record by keep less than 15sec
  • before voice start and keep the whole record up to the end (sequence can be cut anywhere after end of sounds, but not too long to avoid excessive upload time ).

Fields “Company or title” and “Studio” are used to rank measurements in a structure \title\studio\date\, date being automaticaly written. So you can check evolution of performances in time and see any degradation. Important to avoid use of company name for which you have no rights, your account may be terminated without notice.

Field “Studio” : for home users with just one audio system, you may leave this field empty or fill with “home” or “listening room” or “without correction, “with correction”, aso.

No accents or special characters in he fields « company » and « studio » , because those fields are used as directory names. Allowed characters are alphabets, numbers, space and underscore (_). No space or _ at start or end.

Field “Target” : “Auto music” is recommended for HiFi and “Auto cinema” for home-cinema. For calibration of theaters or mixing rooms, SMPTE targets maybe be used.

“Timbre target” : the standard “Balanced” can be adjusted on user preferences to Sharp (brighter, more high frequencies) or Warm (darker, more low frequencies). Difference to “Balanced” is a slope of approximatively +-0.3dB/oct (exact value depends on measurements,  distances and directivity) so nearly +2dB at 10kHz for “Sharp” and -2dB at 10kHz for “Warm”.

“LF target” : low frequency target is defined by cutoff frequency and level : hereunder  “405” gives a +5dB level and a 40Hz cut. Level at 40Hz is +5-3=+2dB. Level at 130Hz is half max level so +5/2=+2.5dB.

Field to choose Test/Measure/Correction :

“Test” allows to verify if the record is valid to give correct measurements, see hereunder.

“New correction” is possibility to keep all values of the form and just change “Timbre target” and/or “LF target” to reprocess. You may want to change the record name so not to loose old corrections and be able to compare.

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MMM is a measuring method with a microphone moved by hand near the listening place : response obtained with this method gives a reliable representation of audibility.

The most complete infos about MMM method, I published it a long time ago…

http://www.ohl.to/audio/downloads/MMM-moving-mic-measurement.pdf

Other readings :

https://www.aes.org/e-lib/browse.cfm?elib=19477

https://mountaincrest.net/dev/wp-content/uploads/2018/12/Samsung_Harman_Onyx_AudioSolution_Whitepaper.pdf

MMM howto in video : https://www.youtube.com/watch?v=6RiuwqzjqlQ

https://www.erinsaudiocorner.com/loudspeakers/ interesting because for loudspeaker tests, MMM (called Moving Mic Average by Erin) is compared to Klippel’s results : it simply proves that MMM is very comparable to Harman’s In-Room prediction based on anechoic measurements.

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The test track is a sequence of various signals that are choosen to permit all analysis seen on the graphs :

  • start sequence with synchronisation signal and identification frequency
  • log sine sweeps (Farina signal) for impulse responses, spectrograms, wavelets, distortion,…
  • short bursts for timing analyis
  • pink noises for MMM for independant channels and simultaneous, opposite-phase pink. The pink noise is in conformity with SMPTE standard ST-2095-1, see also here : https://www.ohl.to/archives/395

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Better measurements can give better corrections : generally when you EQ based on a measurement that is not conform to what we hear, the correction may worsen the listening experience ! That’s why we think MMM is a safe and reliable way to mesure and base correction.

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If you do important changes to your room, you should redo measurements and calculate another EQ.

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If you change your loudspeakers positions, you should redo measurements and calculate another EQ. Most changes will affect frequencies under 300Hz.

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REW and ARTA are very nice measurement softwares. But both need some know-how to get valid results. This takes time. And it is difficult to compare between various audio sytems because so many parameters can be different.

Loudspeakers.audio method is quicker, the process gives results that are valid and comparable to others users measurements. But this website and REW, ARTA,… can be nicely complementary.

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It is not our job to recommend some brands. But generally the best loudspeakers come from companies that publish complete technical datas. Just check their websites…

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Really recommended, complete and easy to understand:

Sound Reproduction: The Acoustics and Psychoacoustics of Loudspeakers and Rooms, by Floyd Toole’s

The best information comes from Audio Engineering Society, some information is free but you need to register and pay a yearly fee to have access to the whole library.

Very recommended about FIR correction is Denis Sbragion DRC documentation.

 

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You need to have javascript enabled for your browser and also Active-X for Internet Explorer.

This web site is only to used for acoustics measurements and audio related topics. Uploading other kind of pictures is forbidden and the user may be banned without notice.

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You will find our conditions, privacy and RGPD rules in this page.

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Some ideas, but might take some time :

  • calculate NBD IR, SM IR and LFX in conformity to Sean Olive metrics  but with measured performances instead of predicted ones (I’m a bit uncertain about NBD’s calculation which is not so clear to me)
  • import other calibration files
  • export corrections to other formats (json, pcm,…)
  • export EQ for IIR parametric filters
  • multichannel analysis for 5.1, 7.1, 9.1.4, Dolby Atmos, DTS-X,…
  • multitone distortion analysis

If you have any good idea, just drop me a mail support(at)loudspeakers.audio

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My own web site is www.ohl.to and I’m working in audio for many years, especially in pro audio. I have calibrated hundreds of professional studios, stereo to Atmos and DTS-X, for mixing rooms, movie theaters, broadcasters, post-production and mastering studios, but also some hifi systems. I’m a long time member of the AES and participating to the working group SC-04-08 (Working group on Measurement and equalization of sound systems in rooms). On my website, I published the presentation of MMM  a measurement technique now used by many.

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If you have questions or problems, or a just good suggestion, please send a mail to support(at)loudspeakers.audio

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