ARC not working under 50 Hz (iLoud MTM mkII)

[mjan1002]

Recently bought MTM mkIIs and the ARC room correction is amazing.

However, it seems to ignore my room's huge peak under 50 Hz:



You can see that in the "after" graph, there's still a huge peak under 50 Hz, and this is very audible in some bass/trap tracks.

I've re-measured multiple times with multiple speaker positions, but the software consistently ignores issues under 50 Hz. Is this expected? How do I fix this?

I bought these over the Micro Monitor Pros for the extended bass response, so I don't want to just high pass at 50 Hz. For now, I've high passed one speaker at 40 Hz and the other at 50 Hz, as a crude solution to attenuate the affected range without fully removing it. I've also tried using the "LF" filter in the "Contour" section to attenuate under 50 Hz, but the filter band was too wide.

[kfirpr]

Hi
I just got my MTM Mkii and same problem, did you find what is the cause?

[mavros58]

The example in the X Monitor manual for the precision version of the speakers also shows the corrected curve going up at low frequencies but no hump. Are you sure that the LF Ext settings on the back of the speakers are active when calibrating? I have a sub with cut-off at 80 Hz. So I do not worry much about that part of thr curve.

Using the contour filter you should in principle be able to reduce the effect but you do not see it in the calibration curve but you should hear the effect in a test. The boost might be in fact on purpose to make the LF Ext produce its effect.

By the way, do you guys know if you have to keep X-Monitor on and the speakers connected by USB all the time to keep the calibration active ? If so this is a bit of an issue as you not only occupy two USB slots but as the cables are rather short they hang around between the speakers making passage rather hazardous. If you use the direct calibration without X monitor you do not need any cabling but with the one point measurement your sweetspot gets very narrow.

[Peter_IK]

You do not have to keep X-MONITOR attached. Any changes are loaded to the monitors and not stored in the X-MONITOR unit.

[mavros58]

Thanks Peter, Am I correct that when all Atmos microphones are calibrated I do have to add the delay in X monitor and then save the file and updating the L/R speakers. Or is there some reference delay set based on the distance from the ARC mike entered automatically in X monitor while calibrating. If I understand your answer correctly X monitor can be used for all installed speakers. You just can do two at a time, upload the calibration to the speakers, save the profile and go to the next pair and finally the single center speaker That would be great.

Unfortunately I just got a weird answer from IK support. They tell me:
« You calibrate each speaker separately, you would usually want to put it in the seated listening position pointed at the specific speaker to point the Arc microphone at the speaker I am calibrating « 

Is this correct ? The last bit is not what the manual says. You have to point it straight forward in rhetoric middle between R and L. My question was actually if I have to turn the ARC microphone 180 degrees when calibrating speakers behind the listener (and upward for the overhead speakers) or if I keep it pointing forward for all speakers; front, rear and overhead.

[Peter_IK]

On that I would not know more than IK Support so I'd say ask for some clarification on their statement rather than have me interpret it, honestly.

[mavros58]

Ok I will do that.

[mavros58]

Good news. I received the corrected reply.

The ARC microphone has to remain in the same position as for the stereo calibration. The required delays (for example from Dolby Dardt) have to be entered manually after the calibration of each speaker. The calibration is done using the CAL method.

Here is a nice link which form some reason does not show on top when you Google the topic:
https://www.ikmultimedia.com/faq/index.php?id=1426

They did not mention the use of X Monitor for each pair with intermediate profile saving but it might be interesting to experiment with it.