Read the procedure before jumping on measurements ;)
Hereunder is a description of the whole procedure and you should find more detailed infos in the FAQ
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
keep the mic at listening position : sync bong is followed by 3s left sweep and right sweep. 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
«move mic to front» : place the mic about 30cm front to LP, sweep on left, sweep on right
«move mic to rear» : place the mic about 30cm rear to LP, sweep on left, sweep on right
«slowly move mic » : slowly move mic in a volume of about 1m3 autour du point d’écoute : pink noise 20s on left channel, 20s on right channel, 10s of correlated noise on both channels followed by 10s of pink noise with phase between 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.
Time of process to get graphs is 5 to 10 minutes. Don’t forget to refresh the “Measurement” page.