Part 2 - Dual Subs + MiniDSP = MAGIC!!

[@joentell]

Good stuff George! Glad you figured some stuff out. Have you played with the alignment feature in REW? If you have sweep measurements from REW, they contain time and phase information. What you can do with the alignment is play with delays and levels to see how it affects the predicted summed response. Its usually spot on. It saves you from having to remeasure with each change. Look out for the solid black line which shows you what the optimal summed response would look like so try to target that.

[@GeorgeTheaterAtHome]

Excellent, thank you!

[@christiandickey]

I second that 💯, the alignment tool takes out all guessing and tinkering. Adjust the sliders and you will quickly see what the best adjustments are needed for max performance. Such a great tool.

[@FOH3663]

It's worth noting, when optimizing with DSP, be mindful to utilize all your tools at hand. Often overlooked is manipulating highpass freq and slope to your mains, lowpass freq and slope to the subs. Use every tool possible to optimize summation, as the impact isn't insignificant. Very cool. Appreciate the content.

[@daphoosa]

You need a follow up video using MSO (multi sub optimizer). I got similar results as you using REW, but MSO significantly improved the smoothness and completely eliminated a null that I couldn't remove by hand.

[@GeorgeTheaterAtHome]

MSO looks like a great tool - I'll have to give it a try!

[@ts6640]

@@GeorgeTheaterAtHomeyou really should.

[@bobslave7063]

Thanks for sharing useful experience. What tracks and apps do you use to get that curves?

[@KforConstant]

I believe Anthony Grimani focuses or at least teaches to start with delays as an efficient and effective way to calibrate subs. He has one slide of a calibration that shows just adjusting delay he had a 30db boost in bass, or something crazy good. Thanks for sharing your journey

[@DjJay]

As someone who works with sound for a living for about 15 yrs now. You don't need two subs, specially for such a small room and second because most sound below a 100hz is mixed in mono anyways for a whole lot of reasons, you can look up why sub bass is mixed in mono, standing waves, phase etc etc and most of all localization, human hearing can't tell the directional difference of sub bass frequencies anyways, clubs, event venues and movie theaters all have sub downmixed to mono and for good reason too And I think the most chaos being created is because you have a unmatched pair of subs, because each sub will has a different frequency response curve, which you have seen in your previous video when you ran the REW test in part one from the same location, creating havoc with each other, the RSL (front right, has a better and smoother frequency response so get a second one of that ) just reversing polarity does not really get you phase alignment, the 2ms delay helped because less frequencies were cancelling each other out and creating standing waves. So for BEST result get one sub with the flattest frequency response possible, get a bigger and more powerful one if you want more rumble and place it halfway behind your chair and the back wall and two bass traps for the rear wall corners.

[@GeorgeTheaterAtHome]

I'm definitely going to experiment with that. Thanks for the great advice!

[@BrentWood-yv6cl]

Did you end up doing full sub alignment in the mini dsp, or just set the delays in it?

[@GeorgeTheaterAtHome]

So far just the delays

[@daveboswell9005]

If you are combining 2 subs from different manufacturers you might want to experiment with all-pass filters. Have you looked in to Multi-Sub Optimizer? It will run 1000s of iterations for you in seconds looking at multiple subs and at multiple seats simultaneously.

[@King_Dusty_Of_Pookytopia]

I would crossover the subs at 50Hz.

[@christofg9710]

It would be nice to see the graph of each sub separate. You need to choose a location were both sub compliment each other. It can be that it is not the best location for one sub, but it solves dips in the frequenty of the other sub. For setting the delay, measure both subs separate and then together. Together should always be higher, if not start adding delay to one sub until the output is higher then each sub separate

[@SealedOrPorted]

The miniDSP is a great tool. It is surprising and frustrating when all of the settled audio physics science is proven wrong in one afternoon. Nice results and keep measuring!

[@MAMDAVEM]

A 2 ms delay is equivalent to 2.2ft of distance, is this the diffence in distance between your listening position and the your two subs? I'm also wondering if the null you have at around 70Hz is a room mode and therefore difficult to EQ out? Very nice result by the way.

[@GeorgeTheaterAtHome]

Thank you! Yes, the back sub is about 2 ft further away so that makes sense the front sub would need to be delayed about 2 ms. Good to know!

[@danjones4002]

Yes, really you should start with taking measurements with a tape measure. Set your delay. Then make minor tweaks in delay.

[@BobFrostV]

Which of the two subs do you like more?

[@GeorgeTheaterAtHome]

That’s a tough call. Based purely on performance, the RBH sub outperforms the RSL. But it’s not exactly a fair fight because the RBH is 12” and the RSL is 10”. Also, the RBH is 3 times the price of the RSL. So you have to account for the price/performance ratio.

[@brnmaull]

You should try messing with the time alignment tool on rew its really cool and also makes it easier when u set up your mini dsp

[@GeorgeTheaterAtHome]

Great suggestion! I’ll check that out.

[@hulken82]

+1 on that 👍🏻 then u can easily try every position on each sub together with every position with the other sub. As someone mentioned before, trying to pick the two best locations that complements each other the best.

[@hulken82]

And also, would it make sense to eq the align curve in REW and then ad it to MiniDSP and after that run Dirac live in the Onkyo?

[@BrentWood-yv6cl]

I know you didn’t use bass control yet, but have you tried The Dirac Live Bass Management? If so there is a bug in the software that affects the LPF crossovers. It’s affecting the RZ50 and RZ70. It’s been an issue for awhile and Onkyo still won’t acknowledge it.

[@GeorgeTheaterAtHome]

Interesting! I have been using Bass Management. Was not aware of the issue.

[@BrentWood-yv6cl]

@ yeah if you measure your subs in REW you can see it. I know you use external amps so you could shut off the amps so the front left, right, and center get no power or speaker output. Then measure a full range sweep with the left channel. Then measure your right and center speakers. Change the smoothing to 1:1 and it will make it easy to see. The fronts will default to 120hz crossing and the center will take to whatever you had the fronts crossed at. The high pass filters will work correctly if you measure the speakers later, but the LPF will always be wrong and the Fronts will always default to 120hz regardless of what you set in Dirac. This is an issue what Dirac Live Bass Management and Dirac Live Bass Control on the RZ50 and RZ70. There is a lot of info on AVS forums about it. We have been contacting Onkyo going back as far as November, but Onkyo is still no acknowledging the issue.

[@flyers10az]

Did you do the Harmon excel room mode calculator to see if sitting in a null?

[@GeorgeTheaterAtHome]

Not yet. I’ll have to give that a try.

[@daphoosa]

Your 68hz null is almost certainly infinitely deep. The smoothing just hides it. You're also likely looking at a second null at 95hz as that steep drop off and rebound is not consistent with a typical low pass filter for a sub to mains crossover.

[@rynev3392]

What specifically are you hearing better now vs when they weren’t aligned?

[@GeorgeTheaterAtHome]

The bass is now more even and consistent. It’s also more pronounced, but without being boomy or bloated.

[@Tearial311]

MiniDSP is the reason my system sounds so much better that most peoples

[@MattyDaddy14]

So cool you figured out the delay issue! I know some guys say to add delay to increase sq and spl. But also interesting to see the success with 1 ported sub and one sealed sub! 🎉 Question, could you have made nearly all those changes without the dsp if the receiver has 2 sub outputs? 🎉 thanks

[@micb3rd]

Yes If an AV Receiver or Pre Pro has multiple subwoofer outputs that are "individually controllable" with delay. Most receivers that have multiple subwoofer outputs just send the same signal out of both outputs and thus do not have individual control so no they would be able not make the changes increasing the positive summation and improving the response like the Mini DSP.

[@GeorgeTheaterAtHome]

There were many times during this process I was cursing mixing ported/sealed subs because I figured that was the root issue. Turns out they work just fine 🤷‍♂️

[@spiroszaharakis2648]

@@GeorgeTheaterAtHome Mixing ported and sealed subs is a challenge. I think you should also try with the port of the ported sub blocked off. The inverted phase of the ported sub at the port tuning frequency will always cause trouble and may lead to compromised performance.

[@fonkenful]

Even a relatively short count of 32 comments at the time of my reading this was a bit much more my patience, and I had to pipe in myself. As you didn’t mention anywhere in either video, did you try REW’s “align subs” utility built into the EQ actions tab, I think it was? After taking independent measure of each sub, it allows you to very quickly fuss about with modelling effect of delays and inversion, and might well have saved you those hours of frustration. As for AVRS with multiple independent sub outs, how many of those include the granular level of tuning of the miniDSP? And the MSO that has been mentioned is a Windows only program, and many of us Mac users are loathe to add a virtual Windows to our laptops for that singular application.

[@texxhexxmm]

Mini dsp with Dirac bass Control makes Sense?

[@goat-of-neptune]

problem is, you now have the measurement just in one place, but not in the second position of your 2nd chair. you will need to make several measurements in different places. this is where things are really getting messy so you cant handle them with manual measurenents any longer. you can save a lot if time, by getting a dirac bass control license, which will do the work. best placement of the subs should be one in the middle of the front or sidewall and the other in the middle of the opposite wall. there is a paper from harman on that topic.

[@goat-of-neptune]

and consider the height of the subs as well to fight the mode between the floor and the ceiling.

[@kewlbug]

I'd assume, he sits in the right seat and his wife the left ;)

[@goat-of-neptune]

@@kewlbug a real gentleman for sure he is.

[@michaelgochez7768]

I may be missing something here, and if so please excuse my ignorance... But doesnt dirac calibrate the timing for all the speaker and subs?

[@GeorgeTheaterAtHome]

I have the Onkyo TX-RZ50. It has 2 subwoofer outs. However, they are not independent. So Dirac Live is unable to individually control each sub.

[@michaelgochez7768]

@GeorgeTheaterAtHome That's right, I completely overlooked that detail. Well it's awesome you are taking the time to experiment and bring everyone on the journey. I tried once and quickly was in over my head lol, so I appreciate following olong with with you. Looking forward to more of these. For what its worth, I hear the newer RZ-30 has independent sub outs.

[@chebrubin]

But why use a Mini DSP when you have a Onkyo that supports seperate subwoofer channels output? Not saying using Dirac. Just delay and EQ?

[@GeorgeTheaterAtHome]

The Onkyo TX-RZ50 has two subwoofer outs. But they are not independent. They don’t allow individual control of the two subwoofers.

[@chebrubin]

@GeorgeTheaterAtHome thank you. Are you using the Mini DSP Multi-Sub Optimizer (MSO) functionality?

[@LordMelchiahX]

Do you think your biggest hurdle was the fact the 2 subs are not matching? (Same sub brand and model) Thanks for these videos btw. I know they're a pain in the ass to make and edit.

[@micb3rd]

No not at all, the largest issue is almost all rooms below 200hz have modal issues causing peaks and dips in the response. The frequency of the peaks and dips are determined by the dimensions of the room. Also to elaboate a bit more on different subwoofers , ideally to make life more simple just using sealed subwoofers makes it easier to time align across a wide frequency range as phase interaction is more simple. The port can and will effect Phase both down low and up high so this can make it harder to align. That is not to say it can't work well with different types of subwoofer, I have run similar systems to Theater at Home with sealed and Ported subs and the bass can be fantastic.

[@Scott31415]

It appears you are using Dirac with only one sub output and having a MiniDSP to manage the multiple subs. If you were able to use 2 independent sub channels from your processor then Dirac should be able to calibrate them more precisely. Since you are using a MiniDSP to drive multiple subs then (like others in this comments section suggest) I would recommend using MSO (Multi Sub Optimizer) to first calibrate your subs then use Dirac afterwards. This should give a much better response curve in your sub frequency range.

[@GeorgeTheaterAtHome]

I have the Onkyo TX-RZ50, which does not have independent sub outs. I would love to try out MSO but I’ve heard it only works on Windows and I have a Mac.

[@Scott31415]

@@GeorgeTheaterAtHome Time for Boot Camp 🙃

[@spiroszaharakis2648]

I am looking forward to that 6hr video... While the result is quite good, I think you should try again but this time with a different approach. 1st, the 2ms delay was most likely needed (as already mentioned in another comment) to compensate for the physical difference between the two subs and your listening position. 2nd, I think you would be better off making your measurements with the moving mic technique (use pink noise and move the mic around the listening position to get an average reading and avoid false readings that may happen when you sample only one position) 3rd, use the already documented by the Harman paper positions for subwoofer placement as a starting point and only give up if you can't get a decent curve using the moving mic technique and the appropriate delay. Having said that, I believe that in the end, you will get the best response with either both subs at the middle of the wall position left and right from the listening position, or in the middle of the front and rear wall, or in the left and right corners with the drivers facing the side wall, no more than 6" away from the side wall. Last but not least, make sure you don't try to EQ nulls. It doesn't work.

[@GeorgeTheaterAtHome]

Well now I’ve got another 6 hour experimentation marathon ahead of me. You may indeed get that 6 hour video 😁. Good suggestions, thanks!

[@andrew1977au]

Have you played with the OCA calibration? Most have found they no longer need their minidsp. I just installed some bass shakers to my chairs and man they are so worth it

[@andrew1977au]

If anything, playing with OCA cal has taught me so much more with REW, wait till you getting into impulse and overlaying them to get your speakers aligned correctly.

[@andrew1977au]

Run a sweet with front left, then another sweep with front left and sub together, it should show if that null is an issue, your looking for a clean line from the sub to speaker

[@shaolin95]

No way. Oca is no replacement for MiniDSP at all

[@andrew1977au]

@@shaolin95 have you tried the lastest version of his script? OCA neuron

[@JC_Onofre]

Would you try the Dirac Bass Control update (for a fee) on the rz50? Above that, magic beans? Sorry for being our guinea pig 😅. Looking for see that director's cut.

[@GeorgeTheaterAtHome]

I’m loving Magic Beans! Haven’t tried Bass Control yet. Maybe have to give it a try when I get the $299.

[@bobrocco1203]

Thanks for the video! Did you try to use rew peq on each sub before running Dirac live? Also did you upload Majic beans sub room curve to your Mini dsp 2x4 hd or to Dirac live? 😊

[@Hometheaterdenmark]

Sorry for my somewhat stupid question. But when it comes to dsp. I know zero. Because of my ptsd. I lost out on many years of good knowledge. So here is my Q. I got the X15+ sub active and then i just added a dual 18" passive whic is runned on a crown amp 2502 bridged. Does the mini dsp only work with the same type of subs all around or can i mix both active and passive subs? Again, i dont know anything about connection the mini dsp since i´ve never owned or used one. And all this is i guess depended on how you connect the subs to the mini dsp right. Once again a great video. Keep them coming. Tango out.

[@GeorgeTheaterAtHome]

You can mix active and passive subs with a miniDSP. Use an RCA cable to connect the amp for each sub back the miniDSP and you’re good.

[@GeorgeTheaterAtHome]

Thanks, glad you enjoy the videos!