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Thread: M2 Master Reference Monitor Purchase

  1. #16
    Webmaster Don McRitchie's Avatar
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    Hi Greg

    I really appreciate your input. Given your comments on the non linearity of PC's, the Scarlette 2i2 looks very attractive with its low cost (~$160 on Amazon). The mic remains an open question since I would now be moving away from the USB approach. The Cross Spectrum Labs products still look attractive as per pos's suggestion. They purchase mics, calibrate them and then resell the mics with their specific, individual calibration file.

    Quote Originally Posted by gtimbers View Post
    You need to be able to correct the Octave to Octave balance of your mic to less than 1/2 dB from 100 Hz to 10000 Hz.
    To be honest, I am not clear on what this means. Is this something that calibration would take care of or a completely independent correction process? If the latter, is there a web resource you can point me towards to accomplish this?

    Quote Originally Posted by gtimbers View Post
    Your M2/Crown setup will come with the recommended crossover and EQ already configured. The configuration is for flat response in a chamber and is not correct for a listening room without some adjustment, particularly in the 400 Hz and below region. There are several views regarding EQ above 400 Hz or so. I have had very good results correcting things above 400 Hz if you know something about your loudspeakers directivity behaviour. I have a suggested in-room target shape which is not flat. I will publish my suggestion another day as I don't have the curves with me today.
    I got some preliminary info from JBLPro about the in-room target shape they used for the system I auditioned at Northridge. As in your case, it is not flat. If I have remembered it correctly, it has a gentle shelving of the HF along with a gently rise in the LF response that corresponds with room response recommendations that Dr. Toole developed. They also optionally apply another shelving starting at around 3k if it is subjectively assessed that the midrange has a degree of harshness in a particular room. Other than this, the room tuning has been directed towards correcting room modes below 400 hz as you suggested. I hope to follow-up with Pro to gain the specific target settings used. Other than the shelving, I don't believe Pro hasn't been addressing the response above 400 hz so I am very keen to hear more details on your experience.

    Thanks again for weighing in.

    Don

  2. #17
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    Quote Originally Posted by Don McRitchie View Post
    Hi Bobecca

    My intent is to solely measure room acoustics. I am familiar with how the M2 speaker tuning was developed with extensive analysis and input from the best minds at Harman from both the Pro and Consumer side. I have no intention of messing with that.

    Based on this elaboration on my intent for measurements, would you still recommend using ARTA over REW? From my response above, you can see that I like the simplicity offered by the REW setup where I would not need an external soundcard.

    Regards
    Don
    Good to know. I was just asking to be sure.

    I have both the REW and ARTA and keep ending up using ARTA all the time when room measurements is performed.

    Problem with REW is that everytime one change a mic position, a check of levels has to be performed. For an example, measure at the listening pos after the check levels has been performed and then move that mic near the loudspeaker, there will be a input clipping of that level and measurement invalid. A new check level has to be performed. Then this two measurements cant be evaluated side by side to see any deviation. That problem does not excist in ARTA.

    Another problem is the waterfall plot that has been taken in a room to be compared from a diffrent waterfall plot from another room due to that the preassure level isnt the same. Cant be compared side by side.

    ARTA has burst decay and a waterfall plot and it is always starting from zero on a x-scale. Dosent matter if it is from diffrent rooms, the measurements can be evaluated in respect to room acoustics.

    REW is a good tool if the measurements is performed for that room only. Or if room treatments is involved then one can see the improvement has been acompliched or not, like before and after measurements for that room in specific.

    Hope it makes sence.....

  3. #18
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    My gear with the Cinema screen array and Mctwins system with the PRX and 4429 speakers. Just for reference.

    http://www.gearslutz.com/board/bass-traps-acoustic-panels-foam-etc/651132-my-room.html

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    Quote Originally Posted by gtimbers View Post
    REW 5 is the way to go. Be sure to get the Beta version that corrects the curve averaging method. For Mac, it is Beta 20. I use a Scarlett i212 as an external sound card. Most PC's have lousy frequency response so if you want to use your internal card, just do a loop back with the REW software to be sure things aren't too bad. I have a B & K mic, so I cannot comment on the suggestions others have made for mics. Since you don't have the ability to calibrate your mic, I would suggest sticking with something that is good quality or at least a known entity. If your mic has a non-flat characteristic (smoothed over the full frequency range) you will end up with less than desirable results. You need to be able to correct the Octave to Octave balance of your mic to less than 1/2 dB from 100 Hz to 10000 Hz. I plan to provide steps for in-room measurements and EQ soon, but not today. For now, consider REW 5 to be your software. It is excellent. Get a good mic, or at least one with flat (or known) response. REW has the ability to do a loop back correction for your electronics and it also takes a Txt file for mic calibration.

    You will need to set up a mic array (one measurement at a time is just fine) around your listening position. 3 to 5 positions will be sufficient. If you try to include too large an area, you will cause more problems than you fix. I started with 5 positions and found that what I measured and what I heard did not agree. I found 3 positions that much more closely agreed measurement and sound wise. Just luck. I would start with 5 positions. one at your listening point, and the other 4 as a square or rectangle around the first mic. I typically space the mics about 2 feet from each other. One possibility is like the number 5 on a die (or dice?) Each of the 4 perimeter mics would be 4 ish feet from each other with the center mic in the middle. You should choose the same height for all mics and that height should be your ear height in your actual listening posture. REW can simply measure each mic position individually and then you can average the 5 into a single measurement. REW only has 30 bins so you need to throw away the individual measurements after the Average has been done (to save space).

    Your M2/Crown setup will come with the recommended crossover and EQ already configured. The configuration is for flat response in a chamber and is not correct for a listening room without some adjustment, particularly in the 400 Hz and below region. There are several views regarding EQ above 400 Hz or so. I have had very good results correcting things above 400 Hz if you know something about your loudspeakers directivity behavior. I have a suggested in-room target shape which is not flat. I will publish my suggestion anotherday as I don't have the curves with me today.

    This should be a fun project and you will end up with spectacular results.
    Sign me up, would like to take part of that slope and directivity behavior. I also agree that flat is not the best freq response.

  5. #20
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    Don, I also use the Focusrite 2i2. It's a good quality soundcard ( plus it has nice wrap-around, multi-colored metering ) .

    The calibrated EMM-6 from CSL will more than do the job . For the extra monies, get the Premium Plus calibration package . Note ; I see these mics are out of stock till mid July .

    The usb powered UMIK-1 test mic is another way to go ( the calibrations are reputed to be "alright" ) . One doesn't use any external soundcard ( with this mic since it's "built-in" ) / though the drawback is the built-in pre-amp is set to a somewhat lower gain ( than what you can achieve with using "separates" ). I just received one ( I won it ) though haven't had any real time to suss out it's strengths & weaknesses .
    - FWIW, the usage of a USB test mic usually triggers the caution that one loses the ability to use a second channel ( within REW ) as a timing channel . That is technically true though there is a lash-up "work-around " ( using ASIO4ALL and your computers builtin soundcard ) .

    FWIW, I use REW ( 100 times more than my licensed ARTA or HolmImpulse softwares ) . I believe ARTA ( which is quite affordable ) is worth owning ,( even if for no other reason, than to help one appreciate the GUI of REW ) .


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    Don, forgot to ask.....

    What kind of room do you have? Will there be any in room treatments? or allready treated?

    Just curious how the approach will be when adressing room acoustical problems.

  7. #22
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    Quote Originally Posted by gtimbers View Post
    I plan to provide steps for in-room measurements and EQ soon, but not today. ...
    I have a suggested in-room target shape which is not flat. I will publish my suggestion anotherday
    Wow, waiting for this! Do you have the curve in the format REW can use as "house-curve"?

    Will you provide steps for room-eq only, or for a full active crossover setup? I would really appreciate the latter. I am playing with a full active crossover setup on my 4365s, with the dbx driverack 260. Using REW, scarlet i2i and a dbx rta-m mic with a generic calibration-file for that mic I found on the REW-forum.
    I am especially interested in your recommendations how to measure/setup delay in the crossover with REW.

  8. #23
    Senior Member pos's Avatar
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    Don, look slike you are in good hands

    What correction hardware will you be using?

    If I may suggest an option, miniDSP provides goods solutions for stereo correction, with both IIR and FIR capabilities.

    Their openDRC box comes in digital in/out and analog in/out flavors, and they also have "dirac live" version with the included licenced software ($$) that provide automated corrections based on a target curve, with included measurement software.
    If you prefer the DIY approach, the openDRC is probably the way to go, and its FIR capabilities will even let you correct phase shifts induced by the speakers themselves.

  9. #24
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    Quote Originally Posted by pos View Post
    Don, look slike you are in good hands

    What correction hardware will you be using?

    If I may suggest an option, miniDSP provides goods solutions for stereo correction, with both IIR and FIR capabilities.

    Their openDRC box comes in digital in/out and analog in/out flavors, and they also have "dirac live" version with the included licenced software ($$) that provide automated corrections based on a target curve, with included measurement software.
    If you prefer the DIY approach, the openDRC is probably the way to go, and its FIR capabilities will even let you correct phase shifts induced by the speakers themselves.
    I was under the inpretion that the speakers phase shifts has been taken care of in the Crowns DSP.
    Why bother to correct for the speaker when it is the room itself that has to be dealth with.

    Just saying.....

  10. #25
    Senior Member pos's Avatar
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    Hello Bobecca,

    AFAIK the M2 preset only consists in IIR filters, so no phase correction there.

    I don't want to pollute Don's thread as room correction is a vast topic, but suffice to say the room cannot be dealt with independently of the speakers, and direct signal is still prevalent in how we perceive sound.
    Having a good source with a "tight" impulse (phase linearization helps there) and controlled off axis response (this is where the M2 shines) clearly makes the integration job easier.

  11. #26
    Webmaster Don McRitchie's Avatar
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    Quote Originally Posted by Bobecca View Post
    Don, forgot to ask.....

    What kind of room do you have? Will there be any in room treatments? or allready treated?

    Just curious how the approach will be when adressing room acoustical problems.
    The three pictures illustrate the room. The M2's will be going in my living room to replace the Altec Model 19's currently shown. As the space is my living room/dining room, there is no real opportunity for physical room treatments. Hence the reliance on DSP and room EQ.
    Attached Images Attached Images    

  12. #27
    Senior Member Mctwins's Avatar
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    Quote Originally Posted by pos View Post
    Hello Bobecca,

    AFAIK the M2 preset only consists in IIR filters, so no phase correction there.

    I don't want to pollute Don's thread as room correction is a vast topic, but suffice to say the room cannot be dealt with independently of the speakers, and direct signal is still prevalent in how we perceive sound.
    Having a good source with a "tight" impulse (phase linearization helps there) and controlled off axis response (this is where the M2 shines) clearly makes the integration job easier.
    Hallo!

    You are not correct here, in Crowns there is both IIR and FIR filters. Quoting from the manual under features on page 5.

    5. Onboard high-definition DSP with 24-bit, 192 kHz Cirrus Logic SHARC A/D
    and D/A converters. Advanced IIR filters and linear-phase FIR filters.



  13. #28
    Senior Member Mctwins's Avatar
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    Hallo!

    I did some test with the REW and posted a thread on GS and come to the conclusion that REW is very sensitive to enviormental noice. ARTA's is more stable here in this regard.

    Read here.

    http://www.gearslutz.com/board/studio-building-acoustics/869303-rew-measurements.html


    I have seen many measurements with REW on GS with various SPL level, some has 160dB and some has 50dB. It is very difficult to compare these two measurements. In my own case with two different rooms with the same settings on REW and with same setting on the preamp and using the same soundcard and the check level is done there is more SPL level with the Cinema Screen than with the PRX600, go figure. Here the waterfall is totally useless to compare because of the difference in SPL level.

    On ARTA, the Waterfall(CSD) and Burstdecay starts from 0 and down(0, -10,-30) despite the SPL level on the freq response, easier to compare various measurements.

    For example, I can't use REW to tune my Varitunes(Helmholtz) devices because inside the Varitunes there is so much preasure that the REW is totally wortless. The signal goes into clipping and I tried to check level with no succes. Maybe becasue REW is using sweep and ARTA is using periodic noice exitation. Like thishttp://www.gearslutz.com/board/10017494-post372.html

    In my opinion, the REW stands no chance compared to ARTA.
    Last edited by Mctwins; 06-30-2014 at 11:17 PM. Reason: adding link

  14. #29
    Senior Member Mctwins's Avatar
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    Quote Originally Posted by Don McRitchie View Post
    The three pictures illustrate the room. The M2's will be going in my living room to replace the Altec Model 19's currently shown. As the space is my living room/dining room, there is no real opportunity for physical room treatments. Hence the reliance on DSP and room EQ.
    Nice looking room......

    My advice, you will have a hard time adjusting your room with only EQ and DSP. NO EQ or DSP will decrease or solve your modal resonances in the room, wheater it is called FIR or IIR filters. You may achive smoother freq response but the resonances will still be there. You have to, wheather you like it or not, solve your room anomalies and not your speaker, two differen't things.

  15. #30
    Senior Member pos's Avatar
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    Quote Originally Posted by Mctwins View Post
    Hallo!

    You are not correct here, in Crowns there is both IIR and FIR filters. Quoting from the manual under features on page 5.

    5. Onboard high-definition DSP with 24-bit, 192 kHz Cirrus Logic SHARC A/D
    and D/A converters. Advanced IIR filters and linear-phase FIR filters.


    The I-Tech HD amps indeed have FIR capabilities, but they are not used in the M2 preset, and for good reasons:
    The control software (System Architect) only allows for a very limited FIR interface where you can only choose between LR4, LR8 and brickwall linear phase FIR filters in place of the IIR ones.

    This would not be practical for the M2 (or any real world loudspeaker really) as you cannot take into account the natural (minimum-phase) response of the transducers.
    Obtaining an amplitude-complementary and phase-coherent crossover with these would be quite tedious (you would have to add all-passes to some channels!), and would not result in a linear-phase response anyway. To get something usable and close to linear-phase you would have to cross the drivers several octaves inside their passband...

    It would be nice if System Architect could let the user load FIR coefficients generated by external programs, such as DRC-FIR or Align2 for room correction, or rePhase for crossover and manual amplitude and phase corrections (I am the developer of that software).
    The openDRC platform let you do just that.

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