Here's my findings using MC DSP room correction bass management on LFE for 2.1 music and 5.1 music vs 5.1/7.1 Movies in 2 different zones.
The 7.1 zone is set for movies and multi-channel Audio.
The 2.1 zone is for all stereo sources.
Use the MC21 built-in 5.1/7.1 volume level calibration first on the 7.1 zone and check for the speaker with the lowest level.
You want to trim all other channels down to the lowest level channel so you don't introduce clipping.
Set the level on your lowest measured channel so the meter reading is 75db and then use either PEQ offset or Room Correction offset to get the other channels down to match your lowest channel reading on the meter.
After Dirac or EQ adjustments you'll need to come back and re-check volume level again to trim channels down to the lowest speaker reading on the meter.
For the 5.1/7.1 zone all channels should read 75db on the meter including the LFE when using the built-in MC21 Volume 5.1or7.1 channel Level Calibration.
Keep in mind:
Digital level adjustment should always be down as a preference where possible to avoid clipping further down the signal chain.
You should also turn the SUB AMP volume up on the SUB if LFE level is too low so you don't push MC21 into clipping protection.
Baseline LFE meter reading before correction can be upto 10db over your mains without any digital correction (trim) because you can always pull the LFE back down with trim.
You may need to play around with Room Correction Bass redirection crossover slopes and frequencies between stereo and 5.1/7.1 zones to match the characteristics of your main speakers with the Sub(s). Changing the slopes and crossover region will create different peaks and nulls.
In theory the same cross over slopes and frequencies should work for both 2.1 and 5.1 but I found that not to be the case.
I recommend experimenting with the built in MC21 tones for the bass region from 20hz to 200hz to check the best blend of main to sub to find the right crossover point and slope. This will take quite a while.
If you have the luxury of moving your SUB (or SUBs) around the room you should check for the spot with the flattest SUB response for each SUB before tuning overall levels.
If you cant defeat the SUB built-in crossover, you should turn it upto it's highest frequency (usually 200hz) so that it doesn't interfere with JR bass management cross overs.
You should also set your AMP LFE cross over to it's lowest setting (or large speakers) to avoid interference with the MC crossover settings.
For example my Sony AVR is set to 40Hz LFE crossover with speakers set to large.
Now you have 5.1/7.1 tuned you can move on to tuning the 2.1channel stereo zone.
I copied my 7.1 zone to a new 2.1 zone to start from there.
If your lucky all you'll need to do is check the tick box in DSP studio for convert stereo to 2.1 on you stereo 2.1 zone and your levels will all be good for the test tones from 20hz to 200hz.
To check 2.1 channel stereo calibration I create a PEQ block to mute all channels except left and SUB and then run MC21 built in test tones to check frequency blend and level from 20hz to 200hz. Do the same for right channel.
PEQ-mute by
Hilton, on Flickr
Unfortunatley some AMPS and Pre-AMPS handle LFE processing and level differently with multichannel PCM or analog inputs vs decoding DTS or multichannel in the AMP/Pre-AMP.
This may mean you need to do some level adjustments for the SUB in 2.1 stereo mode.
Because we can set upto 10-15db higher sub level in the multi-channel zone, if the sub levels are too low in 2 channel zone, we have the room to bring the sub level back up without clipping by just setting the SUB offset back to 0.
If you're experimenting with different crossover slopes and frequencies between 2channel and multichannel you may need to go back and forth between each zone and adjust levels. The goal is to always have the Sub over-level in multichannel so you can bring it back down to 0 offset in 2 channel mode. (and bring it down with -10 offset in multichannel)
(usually 10db)
Having just moved house and retuned my system it took me a few days and several hours per session to finish the job.
I have nice phat bass that's not too overpowering in movie mode and multi-channel music mode and clean tight bass in 2.1 stereo mode.
Your mileage may vary, but that's how I've approached it. I'm open to comments and feedback if anyone thinks there's a better way.
In the end I have NO PEQ frequency adjustments, only level adjustments to match mains and Sub levels.
PS. I have -3db in 2 channel on sub probably because I have dual mono SUBs. ie same signal for LFE to both subs and mono bass redirection to both subs. (amp and sound card are both only mono sub output)
I also have the luxury of having matched floor standing full range speakers for my 6 channels with a matched centre channel so my crossover points and slopes are the same for each channel.
7.1 zone output
7.1zone-output by
Hilton, on Flickr
7.1 zone room correction for SUB
7.1zone-room-sub by
Hilton, on Flickr
7.1 zone room correction for Left
7.1zone-room-left by
Hilton, on Flickr
2.1 zone output
2.1zone-output by
Hilton, on Flickr
2.1 zone room correction for SUB
2.1zone-room-sub by
Hilton, on Flickr
2.1 zone room correction for Left
2.1zone-room-left by
Hilton, on Flickr