Subwoofer Scramble: Combining 15" AND 18" Subs In The Same Rig?

►► Get the OSM, GLL, and trace files here: www.producedbymkc.com/audiotoolkit
Sometimes you gotta make a PA Salad - combining subs of differing size and specs together to make a uniform rig.
Will this get you in trouble?
Today I'd like you walk you through not only the answer to this question, but the process in which I got there. How I was able to source measurement, analyze the data, and see what processing I needed to make for a killer sounding low end.
We'll cover:
- How important is phase vs SPL in this equation?
- Should I turn down the bigger sub or turn up the smaller sub?
- How can I measure my own gear to make sure it'll work?
🔗 Video Links:
Open Sound Meter - opensoundmeter.com/
EASE GLL Viewer - www.afmg.eu/en/gll-viewer
#systemdesign #systemtuning #livesound #liveaudio #sounddesign #audioengineering #soundoptimization #liveaudio #concertsound #audiomath #systemtuning #proaudio #soundengineering #soundtech #sounddesigner

[@a.h.1665]

HOW TO ALIGN DIFFERENT SPEAKERS: if you have full access to the dsp of the speakers, then its easy matchable. If you dont, i recommend, you dont mix speakers. If you have full access to dsp, do as following: 18" subbass, HPF at around 25hz to LPF 80hz, 15" Kickbass, HPF from 80hz to LPF 125hz Meassure speakers without any EQ. Meassure SPL, Phase and impulse-response Meassure and Align Speakers with their SPL, Phase and impulse response, each independently. Start with Impulse response, then Phase, then SPL. Its not just about phase or SPL. Impulse has to fit as well, to get matching Impulse (18" usually slower then 15") you have to add a certain delay to the speakers, before you start matching the phase. You have to try and error with Phase-meassure and Impulse-meassure, until the speakers match perfectly Use the same filter at the crossover frequency E.g: 18" sub: High pass filter e.g. 18dB Butterworth, Low pass filter: 24dB Linkwitz-Riley 15" sub: High pass FIlter has to be 24dB Linkwitz-Riley as well, to get a perfect summation. Sometimes, you have to add an all pass filter to the system to get the impulse and phase matched perfectly. add those filters in your dsp. you have to play with the Filtertypes to find the perfect filter for your system. Sometimes its Butterworth, Linkwitz-Riley or Bessel, sometimes even a more unique one as Hartmann or LIR. Tops: Make sure, you have matching tops for your 15" sub. If not, repeat the procedure above with the 15" sub and the tops. EQ-Settings: DO those, after you matched phase and impulse perfectly and apply them on the whole speaker-group, not just to the single speakers. otherwise, your phase will shift again and you have mismatch. Always just EQ the whole, summed signal. Important: You usually meassure the speakers at a certain position. If you move the speakers and place them in a different setup, your meassure is not coherant anymore and you have to meassure again.

[@_LaszloTuri_L-sound_]

Hi! You made my day, I uploaded this measurement to tracebook! It's so cool to be in your video! One of my dreams came true!

[@MichaelCurtisAudio]

Very cool! Thanks for letting me know and I appreciate you uploading the trace. Have a good one.

[@bradywilliams2951]

I don't know if you noticed this or not, but the Vector Sum didn't cange at all by reducing the volume of the 18" (timeline 18:19). It just made it look relatively higher compared to the individaul speaker graphs which are now normalized by bringing the 18" down. I backed the time up to 16:20 and the Vector Sum is stil right at 18dB at 63hz. Just a heads up.. please let me know if I've misunderstood anything, thanks!

[@AmpedZWeb]

This is so technical and I feel I need to do it on my entire 3 systems.

[@soundsationsweddingdjservi1263]

I'm a DJ and I often have to do big school Grads with 1500 plus guests. Schools don't have huge budgets, so I can't charge them enough to allow me to rent extra gear and have to make the best of what I have. I can cover the mid/highs no problem but of course kids that age want lots of hip hop and lots of low end. I have 2 older QSC hpr181i subs that I usually put together side by side in front of center stage with the mid/high's at the left and right. It sounds OK (even though I have to spend all night removing peoples drinks from the subs). I also have 2 older Mackie SWA1501's. Is there any way I could incorporate those into the setup for a little more bass coverage or would that cause problems? Any feedback would be appreciated!

[@paulboregard4056]

Watching a lot of your videos lately and I'm very grateful for all the information you provide. Started reading "Sound Systems: Design and Optimization" by Bob McCarthy and really do enjoy digging into this topic. Thanks for your work!

[@MichaelCurtisAudio]

So glad to hear that! Make sure to check out Michael Lawrence's book, Between The Lines: Concepts In Sound System Design & Alignment, as well.

[@aaronl7669]

fantastic. if you had the two subs, would you then set them up and tweak the delay and volume to see what sounds best?

[@troytully5688]

I'm wondering the same thing!

[@camaross12]

Awesome video. Helping me learn. I’ve been trying to make 10 subwoofers work well together. I will work on phase and gain matching to see if I can get most out of my subwoofer summing. I’m trying to sum 3 different types of boxes so it may not be possible or give a desired result but something for me to play with. Do I need a controller to get proper measurements? In the past I have used a usb controller with in and out but lately I’ve been using umik and Bluetooth but I’m not getting a proper phase graph unless I use REW.

[@isaacsitiakalaabwenje]

Thanks to you Micheal Curtis For through your teachings I'm graduating as A very Cool Sound Engineer Who can Be trusted wherever I go for A Gig. I have learnt something about the two combinations of the 15"" and 18"" SUBs

[@henrikviktorsson]

Great video! But how do you physically align different sized subwoofers when you start playing with delays to get the phasing right? Place them so the front grills line up or what?

[@viktorzacik8988]

You measure it. You can put everything in one line just dont forget that you need an extra processing output for this kind of setup.

[@SrPostostes]

Hello Michael, can you please explain on how do a graphic looks or whats the best position if you place main speakers and subs facing each other on a rectangular building, two mains and 2 subs on each side 🙏🏼

[@grayancyagra5334]

Very appropriate the way that you show us set up for PA. Is DBX DriverRack PA management Can Also align correctly PA sub without to use open sound meter?

[@robertdeniero]

Hi Michael, I am quite a noob and I am very intrigued by your videos. I've already watched your video about the 2 sub placement. I have 2 different subs (15 and 18 inch alto pro) and was also interested in the subject of this video. How is the speaker placement related in your 15+18 sub combo example? Because both measurements are done 2M in front of the sub, I assume that in this hypothetical situation, the subs are stacked. Is this correct? How would the sub placement with a certain distance in between instead of polarity inversion have an effect on the sound? Or should I bring the subs as close as possible to each other with 1 in polarity inversion? Thanks!

[@tony8236]

great Michael. I wanted to ask you if possible. if I have 2 x18 subs and 2 x15 subs is it possible to create a line gradient by placing the 15 subs behind? I've seen that many companies make subs that start out cardioid but have different speakers inside

[@phutran2006]

Very informative. Thanks Michael

[@aaronyoungberg8258]

Great video, super helpful! Related question, is it possible to use two different subs (KS112 & KW181 for example) to create a cardioid sub configurations? Which driver would you position forwards vs back/ invert polarity? How would level matching between the two different subs help or hinder? Thanks for your time!

[@MichaelCurtisAudio]

Yes, it is possibly to combine two different subs for a cardioid setup as long as they're matched in level and have a similar phase response. Just know your headroom will need to be limited to the small/less SPL capable sub. I'd put the sub with the smaller driver facing forward.

[@henryvanschalkwyk2133]

Thanks for the video, how about sending kickdrum only to the 18s and then bass guitar only to the 15s

[@MichaelCurtisAudio]

That'd be an interesting way to divide up LF duties. Give it a whirl.

[@Yohan_pro]

Greetings, I have a problem, open sound meter there is a sampling frequency error, when I have the vector

[@johnmcquay82]

A superb video once again.

[@electricashman]

Are you local in Tucson? I’m just a hobbiest but have some phase alignment woes that might be good content for you.

[@YiPSKiPP]

If I am following this alignment process in real life, should I still hit hit 'apply estimated delay' when taking measurements in Open Sound Meter or will that mess with the data?

[@MichaelCurtisAudio]

OSM will have a very hard time applying any estimated delay on a subwoofer. It doesn't have a "spike" in the impulse response to latch on to (which is only present in high frequencies). I would plug in a delay value yourself with one of the subs soloed to get the phase flat in the center of the sub range, then kick on your other sub soloed and compare.

[@lootguitar]

great video! well done.

[@rolandomota7474]

Golden!!! Thanks Michael!!

[@laszloturi9633]

Awesome and helpful video! Thanks mate!

[@douglasallen534]

Great video but you forgot one very important thing. How far apart the subs are from each other. In order to get this summation, they have to be close to or right against each other. Most like to place subs 1/4 wavelength or closer together of a given frequency within the desired bandwidth. For example, 80hz is approximately 15 feet in length so you'd want the 2 subs to be closer to each other than 3 1/2 feet. I like to go 1/8th wavelength or right up beside each other. When the subs start to be farther away from each other than that then it will affect the summation depending on the listening location in the form of power alley.

[@MichaelCurtisAudio]

You're right. I cover how physical displacement affects coverage pattern extensively in other videos, so didn't want to double up here.

[@videyo098]

I'm struggling to understand some of the fundamentals here. What exactly is the phase response of a single loudspeaker? My understanding of phase is that it's when two or more sound sources arrive at a single point and due to differing propagation paths one source may be say 90 degrees phase shifted from the other at a given frequency. How can a single loudspeaker have a phase response? Surely it's perfectly in phase with itself at all frequencies?

[@HunterShawMusic]

Speaker drivers don’t typically respond at the same speed to different frequencies due to the mass of the driver, lower frequencies taking longer. These responses can be smoothed with digital filters, but that only works for higher frequencies as the low ones would require an unacceptable amount of processing delay to correct due to their longer wavelengths. Also any speaker using All Pass Filters for pattern control (D&B, Meyer) will have a 180* phase wrap wherever the APF is used. Those phase traces look real funny 😄

[@ebpula]

Is open sound meter safe to use on windows 11

[@SilexProduction]

Thank you 🎉🎉 😊

[@intoxicode]

My biggest question is what do you do when you show up to an event and then there's different types of subwoofers, from different manufacturers. Without analyzation equipment and time to download files. How would you deploy these for the best sound would you just put them side by side in a center configuration and leave them be or would you actually try to cardioid them even though they're different manufacturers without any kind of measurements or equipment... Not everyone has access to laptops measurement equipment and microphones so we need to be able to figure out how to set this stuff up without software..

[@MichaelCurtisAudio]

Great question. I'd assess the gig and see how much of a positive impact a cardioid setup would bring. Then also see if I need the SPL output of both subs vs just a single sub. I would put the two subs right next to each other, turn one on and one off, listen to pink, then turn the other on as well and listen to the result. If the level got softer, invert polarity on one and listen again. It could also be a timing thing, not necessarily polarity.

[@intoxicode]

@@MichaelCurtisAudio Great response! Thanks for the input. Been trying to figure this out all week

[@intoxicode]

@@MichaelCurtisAudio It's pretty crazy how you can pretty much hear power alleys and valleys if you just walk around..

[@gavmurray7398]

nice one!

[@ladjkaoz]

wow... for years I been telling my friends to dont buy all kind of subs or speaker just cause they are cheap. I used to tell them to just stick to one model... I never though phase alignment was this critical.

[@elektronickejora554]

Nyimak master

[@joe-andreypieternella7720]

Luckily it is no longer necessary to normalize the content in the txt file. At least for the people using OSM.

[@MrNicknayme]

I had hoped for using the 18” as infra below the 15”. Not making them do the same frequencies.. Hint-hint..

[@MichaelCurtisAudio]

If the 18" reached down far enough below the 15" that'd be an interesting topic to cover, for sure. For these two particular subs there's too much overlap in frequency response and not enough LF extension in the 18" to pull that off.

[@mattfowler8918]

Second this request. I run 21” Othorns with ES18s above. Would be interested in a 2 way subs crossover and alignment video. Also could be interesting to see your approach and comments on some DIY rigs as I’m sure a heap of your audience is here to learn how to tune the rigs they built. 🤙