how many listening positions are you correcting for?
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Stereo Bass using subwoofers
- Thread starter dkinric
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It’s a couch setup in Dirac, for time aligning in miniDSP, I use only “my” side
Not really, 1KHz is always '0' as far as i recall, or very close to zero. Or maybe i just have good speakers lol.
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You're better off doing what i did, use multisub optimizer and then Dirac as Global EQ. it's very much worth the 3-4 hours learning curve necessary.
when you take measurements, (for both MSO and Dirac) only take 3 or 4 where people will actually sit and listen, Dirac's guidelines just make it worse for those 3 or 4 locations that actually matter.
This was very good suggestions. I have, during two years of examine subwoofer management with 1, 2 or four subwoofers with dsp filtering,came to the same conclusion.
In most of the cases - if highend sound with 2 channels are the goal, only two good subwoofers in stereo , regardless of crossover slope and what frequency the subwoofer and mains are crossed over at, are needed. 3 or 4 subs can be worse - and a waste of time and money. The perceived pitch of each bass note is slightly disturbed if the installation of the loudspeakers are slightly wrong.
After having the correct loudspeaker placement for the mains, ( very important ) the two stereo-subwoofers should be placed near each main loudspeaker, preferable on the place inside the area of left and right speaker.
If you previously had stereo bass and switched to mono bass without attenuation then relative to the main speaker you would expect to measure a 6 dB boost on the sub. If you draw the target curve below your measurements Dirac will cut. I've tested this myself by drawing different target curves and then electrically measuring the result, if you draw below it will cut.
Of course you might get some weird behavior when switching from stereo to unattenuated mono as you will be effectively shifting your acoustic crossover point as a result of the different levels.
Michael
I didn't attenuate my signal by -6 dB just so i can get more headroom, 6 dB is a shit ton, I thought Dirac can just bring it down?
are the pros really worth the headroom attenuation?
There is no free lunch, if you do not cut by 6 dB you are effectively applying a 6 dB boost to the subs prior to applying Dirac. I guess if you were running in to the 10 dB boost limit in Dirac then not attenuating would be a way to apply more boost to the subs but that is not going to give you any additional headroom. In that case you would need to be careful about running in to clipping in the DSP (always good to measure the net boost so you know above what volume you might experiencing clipping).
Of course Dirac can bring that boost down but it will be applying attenuation to both your subs and main speakers for at least some portion of the crossover region which seems like an inelegant way to solve the problem.
Michael
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I don't use crossovers, just low-pass filters on the subs. I sealed the ports of the mains and i'm never close to maximum linear excursion.
I'm a little bit confused, how would i run into more clipping if i didn't attenuate? I feel like it's the opposite, with more output Dirac would have to boost less. My Dirac live device is the volume control too so it's not an issue anyway.
Is there anything particularly bad about attenuating both mains and subs as long as it's in the room's minimum phase portion?
Even if you do not use a HPF your mains will still have high pass roll off behavior which will form an acoustic crossover with your sub. I also do not use a HPF on my mains but they exhibit a LR2 roll off at 60 Hz which I then integrate with a LR2 @ 60 Hz LPF on the subs.
Again, there is no free lunch. It doesn't matter if you boost by summing L + R, applying PEQ or using Dirac, it is all boost. When you start with L + R summed your baseline is boosted by 6 dB and Dirac can then boost 10 dB on top of that so you are looking at potentially 16 dB of boost. If you attenuate the summed L + R by 6 dB you are now starting with no boost as a baseline and Dirac will only be able to apply 10 dB of boost which limits your potential boost to 10 dB. Depending on how you set your target curve this may not matter but without attenuation you have the potential to apply more boost.
Assuming you are not running a 1st order crossover (again talking acoustic here, not electrical) the combined response of your sub and mains as a result of the crossover will be by definition not minimum phase.
Michael
The thing is that the MiniDSP use 32-bit float internal processing, so as long as the 'final end product' after master volume control does not exceed 0 dBFS I should not run into clipping. it doesn't matter if the signal is above 0 dBFS mid-way through processing.
I would very much appreciate it if you would elaborate a bit on this I'm not sure I quite get it.
I agree that you will have no issues with clipping if you offset your volume control by the appropriate amount. I've repeatedly recommended in this thread (and others) that folks measure the amount of net boost applied so they know what this volume level is. As it stands a conservative assessment would say you have the potential for clipping at volume levels above -16 dB.
Crossovers higher than first order will result in an all pass response of half the crossover order. So a 2nd order crossover will result in 1st order all pass response and a 4th order crossover will result in a 2nd order all pass response. For flat magnitude response the minimum phase response would be flat phase response but an all pass introduces non-flat phase shift. Linkwitz discusses this here -> http://www.linkwitzlab.com/phs-dist.htm.
Here is a hypothetical example which might add some clarity. This example looks at two cases with identical magnitude response that follow a BW2 roll off at 20 Hz, however one of the responses has a LR2 crossover at 80 Hz. You can clearly see that the crossover adds deviation from mininum phase response.
Michael
you're the person who explained to me that the MiniDSP uses 32-bit processing around a year ago here, so I apologize for my previous mansplaining.
the idea behind me not highpassing my mains is just to add one more source of low frequency in the room to bring down the room's statistical variance further, but i feel i didn't give it much of thought in how it changes the phase of the room.
Assuming that you have Klippel Anechoic Data, can you determine what is the LF cut-off / roll-off slope of the speaker? How do you that?
is there a way to keep the subwoofers running above the speaker's cutt-off frequency (again to bring down statistical variance) without negatively effecting the phase of the room?
No worries 
.
I only play around with sealed woofers which makes things a bit simpler, there are a few different methods and in my experience they all mostly line up.
1) Measure in enclosure T/S parameters with Dayton DATS. Specifically with QTC and Fc you can predict the 2nd order high pass behavior.
2) Measure acoustic response with mic very near to woofer dustcap.
3) Rely on measurements of others. For example Linkwitz has done outdoor / ground plane measurements of the LXmini indicating LR2 @ 60 Hz roll off. Dave Reite reproduced these when design the LXmini+ add on subs.
Once you understand the roll off you can also modify the roll off behavior using a Linkwitz transform and/or additional electrical high pass to obtain your desired roll off. For example I could use a Linkwitz transform to change the LR2 (Q = 0.5) @ 60 Hz roll off to BW2 (Q = 0.707) @ 60 Hz and then apply a BW2 @ 60 Hz electrical HPF and this would result in LR4 @ 60 Hz roll off.
The other variable to consider is that delay as a result of path length differences between the woofer and subwoofer will change phase response and impact how the crossover sums. Linkwitz discusses this here -> https://www.linkwitzlab.com/frontiers_5.htm. In general this analysis treats the subwoofer as just another driver that requires proper integration with the woofer. I also consider the high pass behavior of the subwoofer in the crossover design by applying a HPF equivalent to subwoofer rolloff to the woofer for better phase matching.
To me it is not so much that the crossover negatively impacts phase response it is more that if you don't start from a properly summed crossover in addition to the room you now have the added variable of frequency response issues created by the crossover. For modestly sloped crossovers phase distortion does not seem like a major issue, it is possible to use linear phase crossovers to eliminate the phase distortion but that requires a lot of processing power at low frequencies and has other drawbacks.
Of course YMMV, everyone has different rooms, speakers and listening preferences. I find integrating subwoofers as described above works well for me, it may not be the best solution for you.
Michael
.I only play around with sealed woofers which makes things a bit simpler, there are a few different methods and in my experience they all mostly line up.
1) Measure in enclosure T/S parameters with Dayton DATS. Specifically with QTC and Fc you can predict the 2nd order high pass behavior.
2) Measure acoustic response with mic very near to woofer dustcap.
3) Rely on measurements of others.
For example Linkwitz has done outdoor / ground plane measurements of the LXmini indicating LR2 @ 60 Hz roll off. Dave Reite reproduced these when design the LXmini+ add on subs.Once you understand the roll off you can also modify the roll off behavior using a Linkwitz transform and/or additional electrical high pass to obtain your desired roll off. For example I could use a Linkwitz transform to change the LR2 (Q = 0.5) @ 60 Hz roll off to BW2 (Q = 0.707) @ 60 Hz and then apply a BW2 @ 60 Hz electrical HPF and this would result in LR4 @ 60 Hz roll off.
The other variable to consider is that delay as a result of path length differences between the woofer and subwoofer will change phase response and impact how the crossover sums. Linkwitz discusses this here -> https://www.linkwitzlab.com/frontiers_5.htm. In general this analysis treats the subwoofer as just another driver that requires proper integration with the woofer. I also consider the high pass behavior of the subwoofer in the crossover design by applying a HPF equivalent to subwoofer rolloff to the woofer for better phase matching.
To me it is not so much that the crossover negatively impacts phase response it is more that if you don't start from a properly summed crossover in addition to the room you now have the added variable of frequency response issues created by the crossover. For modestly sloped crossovers phase distortion does not seem like a major issue, it is possible to use linear phase crossovers to eliminate the phase distortion but that requires a lot of processing power at low frequencies and has other drawbacks.
Of course YMMV, everyone has different rooms, speakers and listening preferences. I find integrating subwoofers as described above works well for me, it may not be the best solution for you.
Michael
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Soundmixer
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You are deflecting big time. You haven't been able to prove that stereo bass actually exists. You haven't posted a single piece of research that says it does. I call bullshitake on this statement.
All are below 80hz brightness! LOLOLOLOL!!!!
LOLOLOLOLOLOLOLOL!!!!!!! The good ole posture and bail move. You lost credibility when you asked someone to "sense" something they should actually hear. This is rich!
I realize that through the use of a broken android phone there have been many inaccurate spellings of names. Therefore as seeing it fit to clarify such obfuscations I have created this illumined illustration.
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Theres is much confusion here.
What is music? Its not sine-sweeps or a tone at a single frequence. Music is ordered sounds in the time/frequency domain.
One simple explanation:
An electric bass plays frequencies from about 41 Hz to 8 KHz . Each tone the bass player plays has information from about 41 Hz and up to 8 KHz . If you change the spectra at 5 kHz just a couple of Hz, the sound from the electrical bass will start to sound slightly out of tune. The perceived pitch of the tunes the bass player plays, has become worse.
Now you can start to count and make questions for yourself .
1. How long is the wavelenght at for example 5 KHz ?
2. After counting , is the placement of the two subwoofers important ? Should the subwoofers be placed near the main speakers, or far away ? Maybe you´re now saying it dont make any sense because you´re crossing at 80 Hz - a much lower frequency than 5 kHz ? But hear this….
3. There is no such thing as a perfectly steep crossover, because the subwoofer itself is making noise above the crossover region. Always. Its mecanical distortion from the drivers and the loudspeakerbox AND the room . The last thing is very important to understand.
A subwoofer placed against a wall thats not very rigid is gonna distort the wall- and its very audible. The floor also distort the sound.
When one understands this , its clear that two subwoofers in stereo placed near the main speaker is the best option, if we are talking two channel sound. This is also very easy to verify with listening tests with real music.
5.1 is a somewhat different story, because you have an active channel ( 0.1 ) for the subwoofer with real effects recorded in the studio.
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Not sure this is really true. Don't know how Dirac works, but most source material will not have bass panned 100% to the right or left. In reality most sub bass frequencies will already be in mono, or at least not panned 100%. Thus the signal will already be sent to both channels (both subs). So for most material, you will not notice any difference in level when switching from stereo to mono.
I have the Antimode X4 preamplifier which has a switch for mono/stereo subwoofers. There's no immediately noticeable change in bass level when you flip this.
I agree that bass content will more or less be the same between left and right channels, so if you sum two identical signals you should see a 6 dB increase. I’ve measured this in many miniDSP products and it is readily apparent on the output meters. In miniDSP there is not a switch between stereo/mono, it is a mixer.
Michael
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