EQing only for MLP - REW vs MSO vs Dirac?

[klettermann]

With practice I've gotten better/faster with these techniques, enough so to obsessively repeat again and again and again and...... Well, faster at least. Anyway, I'm really only interested in EQing for MLP in a 2.2 audio setup. I'm gradually coming to find that my best results are with REW EQing of subs and mains and followed by setting delay on subs and then level matching subs and mains. MSO doesn't seem to do better and is a lot more work. Dirac seems worst of all with compromised imaging and soundstage. To be clear, it's easy and better than no EQing at all, but certainly not as nice as REW. Room is W12xL22xH7ft and moderately treated with ASC bass traps. I'm using MiniDSP studio, Maggie MGIIIa's with old school ML amp and cheapo subs. Thoughts or comments? Thanks and cheers,

 

[Flaesh]

setting delay on subs

More often, a delay is needed for mains.

 

[klettermann]

In the meantime of I'm-not-sure-what, fair enough. In my next round of fiddling I'll explore that. In the meantime, thoughts on the topic?

 

[Keith_W]

These three products are different.

Dirac is an automated DRC that equalises the entire frequency response to a target curve. I do not think there is a way to avoid the full range correction, at least not with the last version of Dirac I looked at which was a few years ago. Dirac is also notoriously buggy and there are many complaints about failing to correct more than one subwoofer in a multi-sub system, missing bass, and sending corrections the wrong way. Sadly the DSP market is very small and I do not think there is a better option for beginners.

MSO is a semi-automated DRC that corrects for bass only. It has no ability to do anything else, apart from what it was designed for - brute force optimisation of multiple speakers and subwoofers to provide the most even bass for a listening area. If you believe that only the bass should be corrected and the upper frequencies left alone, MSO is a great tool, and it is free. However it is a bit difficult to use even with the extensive manual.

REW is measurement software, and it was not designed for DRC/DSP so it is lacking many important tools. It is great for taking measurements, but not great for DRC/DSP. It needs to be used in conjunction with other software to fill in the missing features, for e.g. RePhase for crossover generation and phase correction. It does not have a built-in convolver so there is no way to test your filters unless you use more third party software. I am far from a REW expert, so I don't know if it is possible to design target curves, correct multi-way systems, partially correct a frequency response, etc. You need to know what you are doing even before you start. I am not blaming REW for any of this - it was designed for measurement and analysis and not for DRC so it is not fair to judge.

As for which one is the best, that depends on you. If you want to get up and running with minimal effort, Dirac is by far the best. If you are a purist who does not mind the learning curve and struggling with difficult tools, REW + its add-ons is better. But it does not have to be this way - there are other DSP products like Acourate and Audiolense. Both are specialised DSP products explicitly designed for speaker and room correction.

 

[Chr1]

If you are able to use a Windows PC as a source, you can use MathAudio RoomEQ via Foobar2000 free of charge. It is very simple and effective to use. You also have various other DSP options available due to VST compatibility. There is however a bit of a learning curve with Foobar.

 

[ppataki]

In the meantime, thoughts on the topic?

I have been fiddling around with Dirac since v1.1 and with REW for about 10 years. I do not have experience with MSO though.

Dirac seems worst of all with compromised imaging and soundstage

I have also experienced this in the past when I did 1-point measurements only. When I do a 9-point measurement properly, there is no issue with the soundstage (rather on the contrary, it becomes super-clean)
However I need to add that very rarely it can happen that even a 9-point measurement gets screwed up imaging-wise; in that case I just re-measure

My sequence is a bit different: first I apply some pre-EQ (mainly low-shelf to my mains since they are sealed DIY speakers so I need to correct for the 12dB/octave bass roll-off) then I level-match my two subs (with each other and with the mains too using REW) then I apply delay (based on acoustic timing reference measurements in REW with my UMIK-2 mic) then I set my crossover (80Hz, 24dB/octave, Linkwitz-Riley, linear phase using Fabfilter Pro-Q 4 or thEQorange) and then I apply Dirac Live (which won't see the subs since those are already integrated manually) with a completely flat target curve and finally I apply post-EQ (low shelf for the subs and high shelf for the mains)

I have never in my life (so far) been able to EQ the bass with REW to get such a tight and controlled response as with Dirac Live

 

[ZolaIII]

I do one point little wider then my ears and to the sweat spot REW measurements which work good to three seats sofa. Correction is what you make of it, REW is rather capable for it. First I do fundamental room room refraction at uper 70 SPL and so that it doesn't peek to waterfal and in line with other small ones (room) on sub's and per each one (it's 2.2). Then I set crossovers. Mains are ported with port's plugged and sub's are close enclosure. I do orders slope to in room decay which differs a bit then speakers enclosure using Q 071 Butterwort. They are at 120 Hz. Especially paying attention to transition area so that it's not deficient along with shaping rest of the range to the model (with PEQ's by hand. It takes time to do proper and you shouldn't rush it. I set sub's little higher SPL + 2~3 dB so that the target cut is what their reach on their own in mid 30's don't trying to hammer them or pushing it to what's too difficult for them don't do Linkwitz transform. After this is done and I am satisfied how it looks based on measurements I let REW to calculate PEQ's (generic min phase as I use JRiver) up to 500 Hz and put them on (max +2, +3 over all dB). We will both try not to go positive if it's not two step leveling. Do another measurement set parameters and if need be do the mids up to 1 KHz directly with PEQ and wide Q PEQ shaping over it (it's all if needed only). Then if highs are relatively focused not beeming much I do impuls matching start response paying attention not to make it disordered to the end of the process (or pre ringing) and inversion of it (+2 dB max). Bake WAV FIR stereo and put it on to 96 KHz. If need be after measuring I play with phase. I use MC EZ plugins and avoid JRiver embedded convolver. After all of that I do white noise calibration to 88 dB stereo and enable loudness (ISO 226 2003) and it's done.
I use no rool of straight to 1 KHz target as to my finding that does better regarding equal loudness compensation psy. Delay for mains is about 8 ms and usually I juggle between 8 and 9 depending on impulse and phase impact effect. I also autended mains cuple Hz over their Fs and sub's under what they can do (-6 to Fbox). I am in small regular shaped room with limited treatment and not best listening position still close to wall behind but not too close and with small area of dispersion panels behind in line regarding hight and speakers and sub's are close to the wall behind them (about 30 cm) and 60 cm to side walls. Decay times while not best are good enough and in line and I try to keep clarity the same across the indexes. I don't over kill the room and send it dry to it. Speakers are directly a top of sub's (as they are bookshelf's) separated with silicone egg seaters between them, sub's are on their stands and with pack's underneath (together about 6" from floor). Ship flor on on sealing, thick carpet, solid brick walls, wool thick rug and two rows of curtains (thick denim and lighter darkening one's) to the wall with windows and all the way to the corners. Regarding effects I also use PTEQ-X to widen bandwidth a bit (don't use semi vocal PEQ or tube emulator, who likes can and it's pasive no gain). I do EBU R128 to sources I can and compensate back gain (+11 dB) for it. I hope I didn't forget to mention something at least nothing important (writing this sipping my first morning coffee and didn't done it from late autumn). Rest is really up to person doing it to say fun is fun but enough is enough or it's endless game. It's neither easy or something you want to do too often, of course more you do it you get both more realistic expectations and better results. There is no substitute for as possible proper placement.
Edit: for movie's I use old direct show Sonitus Fx plugins pushed into chain in the player (MPC-HE). Surround Fx for stereo sources and compressor smooth mix pre defined preset and to at least 80% of modern titles, there is and vintage one but those rarely need it. Video processing is done by MadVR to the calibrated Panasonic TV or not so good calibrated Epson beemer (basic not compromising kelvin output and to factory movies presset, TV is calman done).

 

[Flaesh]

In the meantime, thoughts on the topic?

Personally, I don't use room correction.
In my system, mains are delayed relative to subs by 5-6ms according to actual measurements.
If your subs are sufficient, you can try the SSS (single source to sink) concept. If the room is suitable for it.

 

[dweeeeb2]

@klettermann your order could be causing problems. You stated “REW EQing of subs and mains and followed by setting delay on subs and then level matching subs and mains. ”

I find that setting delay impacts FR due to constructive / destructive interference. Also I find that I need to level match L to R before level matching with sub. so the order I use is:
EQ L (using MMM for all FR measurements)
EQ R
LVL L=R
set sub delay to mains
EQ Sub with mains
Then check FR with all playing. Some frequencies might combine better than others, so I apply equal correction to L+R for these new peaks.
bit off topic so feel free to ignore, just a suggestion.

And I’ve had no luck with Dirac. REW is the way!

 

[Keith_W]

@klettermann your order could be causing problems. You stated “REW EQing of subs and mains and followed by setting delay on subs and then level matching subs and mains. ”

I find that setting delay impacts FR due to constructive / destructive interference. Also I find that I need to level match L to R before level matching with sub.

Correct. Timing/phase corrections come first, then EQ'ing comes later.

 

[klettermann]

@klettermann your order could be causing problems. You stated “REW EQing of subs and mains and followed by setting delay on subs and then level matching subs and mains. ”

I find that setting delay impacts FR due to constructive / destructive interference. Also I find that I need to level match L to R before level matching with sub. so the order I use is:
EQ L (using MMM for all FR measurements)
EQ R
LVL L=R
set sub delay to mains
EQ Sub with mains
Then check FR with all playing. Some frequencies might combine better than others, so I apply equal correction to L+R for these new peaks.
bit off topic so feel free to ignore, just a suggestion.

And I’ve had no luck with Dirac. REW is the way!

Thanks to all for the comments. It might help to elaborate my REW process a little more, as it seems to be pretty close to the above.

I EQd the respective subs with REW and then time aligned them to create a virtual sub. Obviously Time alignment impacts combined sub FR, so I did a number of iterations. Next a similar process with the mains (no subs). Finally, tried to get mains aligned with subs through successive approximation. Ditto XO setup.

I found that REW's EQing could do pretty good job of this though I was just doing MLP. The REW results are all imported to the MiniDSP for measurement, delay experimentation, etc. I did dirac and MSO in the usual way.

Sonically my main issues are smoothing subs and taming a wild 90hz peak from the mains. The mains are far from flat but honestly still doing damn good and don't seem to benefit all that much from EQing. Hope this clarifies somewhat. Thanks and cheers,

 

[klettermann]

These three products are different.

Dirac is an automated DRC that equalises the entire frequency response to a target curve. I do not think there is a way to avoid the full range correction, at least not with the last version of Dirac I looked at which was a few years ago. Dirac is also notoriously buggy and there are many complaints about failing to correct more than one subwoofer in a multi-sub system, missing bass, and sending corrections the wrong way. Sadly the DSP market is very small and I do not think there is a better option for beginners.

MSO is a semi-automated DRC that corrects for bass only. It has no ability to do anything else, apart from what it was designed for - brute force optimisation of multiple speakers and subwoofers to provide the most even bass for a listening area. If you believe that only the bass should be corrected and the upper frequencies left alone, MSO is a great tool, and it is free. However it is a bit difficult to use even with the extensive manual.

REW is measurement software, and it was not designed for DRC/DSP so it is lacking many important tools. It is great for taking measurements, but not great for DRC/DSP. It needs to be used in conjunction with other software to fill in the missing features, for e.g. RePhase for crossover generation and phase correction. It does not have a built-in convolver so there is no way to test your filters unless you use more third party software. I am far from a REW expert, so I don't know if it is possible to design target curves, correct multi-way systems, partially correct a frequency response, etc. You need to know what you are doing even before you start. I am not blaming REW for any of this - it was designed for measurement and analysis and not for DRC so it is not fair to judge.

As for which one is the best, that depends on you. If you want to get up and running with minimal effort, Dirac is by far the best. If you are a purist who does not mind the learning curve and struggling with difficult tools, REW + its add-ons is better. But it does not have to be this way - there are other DSP products like Acourate and Audiolense. Both are specialised DSP products explicitly designed for speaker and room correction.

Thanks @Keith_W . To elaborate, my goal isn't explicitly to use one kind or another of DSP. It's too do the best I can with what I've got and Im not looking for perfection. That said, I think the tools at hand - Dirac, REW, MSO + MiniDSP studio, or any combinations thereof - should be up to the task.

Also, REW in conjunction with the MiniDSP, does indeed do all the stuff you mention. Measuring, creating filters, target curves etc, importing to minidsp remeasuring etc is quick and easy. Not state of the art DSP perhaps, but does it matter? As I said, I'm only concerned with MLP. Hmmm.... Makes me wonder about using Dirac ONLY for the MLP and REW for the subs. I'm gonna try. Cheers,

 

[LIΟN]

Correct. Timing/phase corrections come first, then EQ'ing comes later.

Are you saying that the timing of the speakers and sub should be set first (i.e., aligned), followed by phase correction, and then finally, EQ applied at the end?

 

[klettermann]

Are you saying that the timing of the speakers and sub should be set first (i.e., aligned), followed by phase correction, and then finally, EQ applied at the end?

And how do you fo that??

 

[Keith_W]

Are you saying that the timing of the speakers and sub should be set first (i.e., aligned), followed by phase correction, and then finally, EQ applied at the end?

Yes. This is because peaks and dips in the frequency response is not caused by amplitude errors, but by timing issues. Cancellation may be due to phase misalignment between speaker and sub, or between subs, or between speakers and reflections. The correct approach would be to address the actual problem - which is in the time domain. Success isn't always guaranteed, so if there are residual issues, we can try boosting dips and cutting peaks.

If we were to adjust EQ first and adjust phase later, peaks and dips might appear as a result.

How do I do that - I time align first, then adjust the delay of the subs so that it is as close to the phase slope of the woofer as possible. This will throw the time alignment off by a few ms. It does not matter if it is within the audibility threshold of group delay (which is between half a period to a period of the frequency in question, e.g. 50Hz has a period of 20ms, so half a period is 10ms). So my target for time alignment is <10ms at 50Hz, <6ms at 80Hz, and so on. If there is residual time misalignment, I use all-pass filters to straighten out the phase slope so that it is a better match whilst checking the sum of the sub and the woofer to see what happens as I adjust. After all this, if there are peaks, I EQ them out. If there are dips, I might try to gently boost them (no more than 5dB). But if the dips are persistent ... time to spend money and buy another sub.

 

[LIΟN]

Yes. This is because peaks and dips in the frequency response is not caused by amplitude errors, but by timing issues. Cancellation may be due to phase misalignment between speaker and sub, or between subs, or between speakers and reflections. The correct approach would be to address the actual problem - which is in the time domain. Success isn't always guaranteed, so if there are residual issues, we can try boosting dips and cutting peaks.

If we were to adjust EQ first and adjust phase later, peaks and dips might appear as a result.

How do I do that - I time align first, then adjust the delay of the subs so that it is as close to the phase slope of the woofer as possible. This will throw the time alignment off by a few ms. It does not matter if it is within the audibility threshold of group delay (which is between half a period to a period of the frequency in question, e.g. 50Hz has a period of 20ms, so half a period is 10ms). So my target for time alignment is <10ms at 50Hz, <6ms at 80Hz, and so on. If there is residual time misalignment, I use all-pass filters to straighten out the phase slope so that it is a better match whilst checking the sum of the sub and the woofer to see what happens as I adjust. After all this, if there are peaks, I EQ them out. If there are dips, I might try to gently boost them (no more than 5dB). But if the dips are persistent ... time to spend money and buy another sub.

So, does that mean you first perform time alignment, then apply the crossover, and finally use EQ to adjust each crossover slope and summation point?

 

[Keith_W]

So, does that mean you first perform time alignment, then apply the crossover, and finally use EQ to adjust each crossover slope and summation point?

No. Crossover comes first, because the XO can interfere with time alignment. The order of operations is:

1. Apply XO
2. Apply amplitude and phase linearisation to driver, if any
3. Time align woofer and all other drivers to tweeter (assuming you have an active multiway setup)
4. Time align sub to tweeter; I don't care too much about being precise because I am going to shift it again in the next step.
5. Phase align sub to woofer
6. Attempt to straighten out any remaining phase issues with all-pass filters. To design an AP filter, use the sub as a guide slope then put the filter into the woofer.
7. Recheck the time alignment to make sure I haven't pushed it out beyond the threshold.
8. Flatten out the remaining peaks and try to boost the dips by no more than 5dB.
9. If any dips remain, look at my dwindling bank balance and cry.

FWIW I use Acourate.

 

[klettermann]

No. Crossover comes first, because the XO can interfere with time alignment. The order of operations is:

1. Apply XO
2. Apply amplitude and phase linearisation to driver, if any
3. Time align woofer and all other drivers to tweeter (assuming you have an active multiway setup)
4. Time align sub to tweeter; I don't care too much about being precise because I am going to shift it again in the next step.
5. Phase align sub to woofer
6. Attempt to straighten out any remaining phase issues with all-pass filters. To design an AP filter, use the sub as a guide slope then put the filter into the woofer.
7. Recheck the time alignment to make sure I haven't pushed it out beyond the threshold.
8. Flatten out the remaining peaks and try to boost the dips by no more than 5dB.
9. If any dips remain, look at my dwindling bank balance and cry.
⁶
FWIW I use Acourate.

Excellent and clear! Thanks much. I'm going to try it that way. Cheers,

 

[LIΟN]

No. Crossover comes first, because the XO can interfere with time alignment. The order of operations is:

1. Apply XO
2. Apply amplitude and phase linearisation to driver, if any
3. Time align woofer and all other drivers to tweeter (assuming you have an active multiway setup)
4. Time align sub to tweeter; I don't care too much about being precise because I am going to shift it again in the next step.
5. Phase align sub to woofer
6. Attempt to straighten out any remaining phase issues with all-pass filters. To design an AP filter, use the sub as a guide slope then put the filter into the woofer.
7. Recheck the time alignment to make sure I haven't pushed it out beyond the threshold.
8. Flatten out the remaining peaks and try to boost the dips by no more than 5dB.
9. If any dips remain, look at my dwindling bank balance and cry.

FWIW I use Acourate.

Uh, that’s why I asked again. I thought the crossover and EQ were applied after time alignment. (At first, I understood what you are saying it as modifying the magnitude response after time alignment.)

 

[Keith_W]

Uh, that’s why I asked again. I thought the crossover and EQ were applied after time alignment. (At first, I understood what you are saying it as modifying the magnitude response after time alignment.)

I'll put it this way. EQ always has to come LAST because it is there to remove residual problems that you can not remove by phase and time alignment. Everything that can affect phase, including crossovers (assuming you are using min phase XO's) has to be adjusted first. You start by adjusting the electrical phase so that it sums correctly, then the acoustic phase. This is why XO's come first.

There are a lot of moving parts you need to adjust. If you try to do it in any other order, you will find it very difficult.