Using a Subwoofer to Improve Midbass in Your Car Audio System

[@DavidK442]

Using real measurements to show the subwoofer and mid-bass null, and your various attempts to understand & reduce them was brilliant. Thank you so much for taking the effort. I have the exact same 60 hz'ish subwoofer null in my sedan, and probably, if I looked closer, the mid-bass suck-out as well. If nothing else, glad to see its not just me.

[@MRB1910]

The best mid bass I ever had was two pro audio JBL 12s directly behind me. Of course that’s not practical for most daily drivers. Great content Erin!

[@johndaddabbo9383]

Ahhh perfect timing, I'm just about to add dual subs in place of my single stock sub and this info will no doubt help. Thanks!

[@lukasHenchman]

also phasing can create bass cancelation, in specific frequencies... sometimes if you turn the phase knob on the subwoofer amplifier it can match the frequencies of the door speakers and reduce cancelation created by the door speakers... also sometimes if the subwoofer is tuned low like 35hz or lower, it can make mids bass weak, especially if the subwoofer is in a big oversized box, that will kill mid bass but make the lows powerful, the speaker doesn't make much preasure let's say 15hz above the box tuning frequency, so maybe if you had a 6th order box, which means one chamber behind the subwoofer and one in front, low and high frequencie chamber to give a boost say at 70-90hz

[@leoeskelinen1867]

Hi Erin and the rest of the community! I really enjoy following your adventures in the car audio world. Especially the posts about measuring techniqes. Have you done tests using gated measurements? Maybe it is all the early reflections that causes the big difference in various methods? Thanks à LOT! Keep up the Good work!

[@ErinsAudioCorner]

Thanks for the comment. I use gated measurements all the time for my speaker testing. But gated measurements in a car is useless. The reason you gate a measurement is to remove the reflections. In a car, the reflections begin within a few inches (much less than 1 ms in time) of the direct sound. Gating to such a small time of 1 ms results in a minimum frequency of about 1kHz. Meaning, your first data point occurs at 1kHz and there is nothing at all below this frequency because everything below is prone to reflection error. Not only that, but your resolution of your data is only captured in multiples of that lowest frequency; in this case 1kHz, 2kHz, 3kHz, etc. That's less than 1/3 octave resolution. If your window time is less than 1 ms (which it will be in nearly every car) then the lowest frequency captured is greater than 1kHz (bad thing). Bottom line: gating the response in a car to remove unwanted reflection is of no practical benefit.

[@leoeskelinen1867]

Erin's Audio Corner Thorough reply indeed! Thanks for that. Then i wont put any more time into gated measurements in car. What is your thoughts about measuring with sine sweep vs pink noise?

[@clydesharman2053]

One trick is to put a sub in the passenger side footwell Like a stereo integrity bm11 It doesn’t require a big enclosure takes plenty of power and really is a helper to 6.5” or 8” midbass drivers

[@jstrahn]

Very educational. I'm going to have to go check out how moving the sub around in my truck affects the midbass null. Already in passenger side extended cab so it may be optimal placement already due to dumb luck.

[@ErinsAudioCorner]

Odds are it probably is best in the passenger side. That seems to be the general case. But definitely try different spots.

[@Blaaake]

I expected I was going to have this same issue. I picked up the JBL Fuse dual 8 inch underseat subwoofers to fill my 60-150hz range. My 15 inch subwoofer in the back handles the rest of the lows. The whole system is out of the truck for sound treatment so I haven’t been able to listen to them, but I sure hope the results were worth the extra money.

[@TickleFingers]

I ran a single JL Audio 12W6V3 sealed and had awesome results up-firing it behind the rear seat on the passenger side of my SUV. I can say that it was super easy to EQ that sub and the left mid-bass null was easy to clean up as well. Now I have the left mid-bass null and my rear firing 2 10" sealed subs have a very strange curve in my current build. I am going to dig out my JL 12W6 and see if I can find the sweet spot and maybe kill two birds with one stone. If the 12W6 does the trick again, I am going to build it a nice box and just abandon my 2 10's.

[@david029014]

can I run just mids in my honda accord interior and let my 12" sub pick up all the frequencies up to my mids????

[@bbfoto7248]

@Erin's Audio Corner Saw your post over on audiosciencereview first which brought me here. :) Great video, dude. 👍👍 Oh NO! Here we go again... :-P Skip it or delete it if you want to! Way back when I first started my car audio journey many years ago, Frank Sbracco Jr @ Traffic Jamz suggested that I place my 15" Infinity Beta subwoofer in the far rear passenger-side corner of my vehicle. At the time, this was a new, but fugly Ford Aerostar Extended Van (chosen soley for it's ability to carry both passengers plus all of my photography & lighting gear and camping equipment comfortably & securely). At the time, a young, tall, and skinny kid named Fred Lynch was busy working on the installation of his white Acura(?) Image Dynamics competition car in the install bay. :) I was obviously a noob and asked Frank WhyTH would placing the subwoofer in the right rear corner make any difference, and he proceeded to explain basically what you have here. He told me it won't cost you anything to try it, so experiment and decide for yourself. I did, and he was right. I had made a 1.75cf sealed, downfiring box for the Beta 15 sub which would slide perfectly under the 3rd row seat when it was folded down flat into a raised bed-like platform, so it was easy to move the subwoofer anywhere within the large rear cargo hatch area. With each new vehicle and install, I would continue to test this theory, and 9 times out of 10, ithe rear passenger side worked best. More importantly, doing all of these subwoofer placement tests really demonstrated to me how different the subwoofer & midbass response could be just due to the position and aiming of the subwoofer within the vehicle, and how different it could be depending on the vehicle itself as well. In my current grocery getter/daily driver, my goal was to keep as much usuable rear cargo area available in the rear hatch. But my design & layout dictated that all of my amplifiers & the DSP be placed in the passenger rear quarter panel cubby where I would normally want my subwoofer. What to do? The result was a custom, forward firing, sealed subwoofer enclosure placed beneath the OEM floor in the rear hatch cargo area. The ~1.85cf (total) sealed enclosure spans the width of the vehicle, and Four 8" subwoofers fire partially under & into the back of the reclining/folding 2nd row seats, which is just a bit aft of the center of the cabin. Each 4-ohm SVC sub is in its own, sealed ~0.45cf airspace, and I installed a pair of individual binding posts for each sub so that I could independently adjust the Levels and T/A of each if desired. The bonus was that after removing the very inefficient plastic under-floor storage tray and then fab'ing a custom tray, I think that I actually gained usable under-floor storage. :) *TL;DR* (but not really, LOL)... What I found through both measurements and listening is that by spreading the "pressure zone" across the width of the vehicle (and also the placement near the center of the vehicle), the bass & midbass response is much more even throughout, and any resulting modes are not nearly as extreme. Overall efficiency and cabin gain was sacrificed a bit with this placement and orientation, but there is more than enough output capability to make up for the difference. The 8" subs are also relatively low-inductance and have excellent xmax, so w/o a LPF they play quite cleanly up to about 260Hz. Sure, I would prefer to have just a bit more extension on the low end, but for 95% of the music that I play there wouldn't be ANY advantage. Completely acceptable compromise. This setup has resulted in one of the absolute best "upfront bass" experiences I've heard, with extremely clean and focused IMAGING of bass both Across the full L-to-R soundstage, and deep into the soundstge. :) One of my buddies was so impressed that he convinced me to build a similar setup in his vehicle...which is the one I recently used stereo microphones at the headrest to record the system and posted the file on DIYMA. D@MN!...Sorry for my usual long-@ss "story time" comment, but I just wanted to share my findings on how I attempted to overcome this same issue. Again, AWESOME video and information, Erin! 👍👍

[@derekjarman1638]

Interesting results Erin - I wonder if that is why the factory sub in my Grand Cherokee is on the right side of the hatch.

[@ErinsAudioCorner]

Possibly so!

[@TheDannorris]

Great video man. I've seen all your klipple stuff from awhile back on diyma. Thanks for sharing.

[@ryanb8736]

Best I’ve had was Focal K2 in front to 80HZ, rear fill speakers coaxial at 120HZ. Sub at 80HZ. That will give sublime sound. Quality amps, speakers, and tuning make all the difference. 12 inch plus sub is the best for deep bass at low frequencies. Also sound dampening helps a lot at that level.

[@Alastasius]

Hey, thanks for the input! By any chance, what were the slopes that you used? 12dB/octave throughout?

[@michaelmyers9857]

Great explanation Erin!

[@ErinsAudioCorner]

Thank you, sir!

[@Nightjar726]

Hey Erin. When you do measurements in your car are we supposed to set the bass and treble settings on the stereo to 0? And the fader in the middle? Thanks!

[@johnviera3884]

Savage video. This is some next level advice Problem #27 These new enhanced mid bass frequencies will cause fun new resonances in the cabin.

[@tfunk1829]

Makes sense of why the woofer of my JL HO12w3 box has the sub more to the right edge of the box rather than centered.

[@kewlbug]

Man, I miss this car audio content

[@jamescorfield534]

Whatever happened to the 6x9 and 4x6 set ups? They sounded the best with the three way woofers.

[@JoshM7]

I guess I got pretty lucky as I can’t recall any nulls around 70-90Hz. It’s been a while since I’ve driven my car (03 Buick Regal) but I remember tuning that thing and it was pretty flat from 26Hz and up. Getting it fixed soon so I’ll be able to enjoy some tunes again. Nothing crazy was done in the car, just had some Alpine SPS rear speakers and a sealed ultimax 10”. The sub technically has almost no output above 60Hz likely because the trunk is eating that area because it’s hungry. But the rear speakers handle above that area perfectly. A tiny bit of EQ for the bass, but mostly just good crossover settings.

[@ReEvoluion]

Erin do you think there would be any real benefit to placing the door mid/midbass driver in a ported enclosure tuned to the center of the null?

[@salinaj2]

Erin, I have an additional question. My measurements from my LMB look very similar. I understand how you dealt with the initial null but what about the one shown between about 150 hz and 325 hz? My LMB behaves that same way and I am looking for any ideas to fill it in.

[@ErinsAudioCorner]

There's really nothing you can do there. It's placement, relative to your listening position. The lower null works out because you have the subwoofer to fill it in. But without another midbass placed somewhere in the car that will fill in the nulls you're talking about, you can't fix this problem.

[@Tmanstomp100]

Bro thank you for this video, I used to do this when I had a 12 inch subwoofer, but sadly it's a bit harder to get my 15 to play higher without getting the coil smelling. the way I've increased my midbass now was by replacing my vapor shield under my door panel with kilmat reinforced with cardboard, it doesn't help quite the same but it's passable, it gives a bit of a bump around 70-100hz

[@johnviera3884]

So a 15 has issues playing up to 100Hz? The listed manufacturer frequency response usually goes up to 500hz. And usually the power handling is weakest around 20Hz. Can you please explain your comment. Thanks.

[@ReEvoluion]

​@@johnviera3884 power handling is generally weakest at 20hz for mechanical/damping reasons not lack of electrical power handling. Actual electrical power handling is determined by the impedance (Ω) curve of the driver and how well the voice coil can dissipate heat. Just as a hypothetical example lets assume we have an impedance curve with a peak impedance of 30 ohms @ 36 Hz (Fs), a min' impedance of 2 ohms @ 80 Hz and a nominal impedance of 4 ohms (DC). With that in mind lets say we have the amplifier gain set to supply 40v @ 4 ohms (400w). Using those values we can calculate the power in watts at those frequencies with a couple of formulas. First find current V / Ω = A Second find wattage V * A = W 36Hz - 40/30=1.33A, 40*1.33 = 53.3w, 80Hz - 40/2=20A, 40*20 = 800w

[@johnd5542]

I had the same idea, thats how I found this video on google search. Thx for the info.

[@akbarrbashaa]

I have the JBL spare wheel sub woofer and cannot play around with the placement. Is there any other way can I improve the mid bass?

[@dc5001]

By adding another set of midbass some were in the car to fill in the nulls, does it matter if the midbass matches the other set upfront?. For example, size, brand, power handling ect?.

[@jerryjoseph1866]

Man i really enjoyed the video Erin...Quick question...If the subwoofer and midbass were crossed over at 100hz.....but the subwoofer had considerably more output say like 2000 watts but that output was EQ'd down to the lowest points of the null in that substage...would that help flatten that frequency response?

[@ErinsAudioCorner]

You mean if your acoustical crossover was 100hz, or if your electrical crossovers were both set to 100hz? EQ'ing down the 'sides' of a null doesn't help the null go away, unfortunately. You still hear it. It just looks less prevalent on the RTA.

[@kcycle1308]

Hi I'm hoping you can help. Recently started to get into aftermarker car audio. My main question is when you run passive with components and even active it seems like with a mid driver like a 6.5 and tweeter. It seems like there usually only a HPF option to block out lower sub frequencys and not a bandpass option for the midrange. Doesnt that mean the mid range will be caught playing some of the high frequency or is it not something it can even play, maby it does but it insignificant? Also if you didn't have your midrange with a HPF and LPF cutting off where the tweeter picks up, would there be an improvement? Thanks!

[@colbylaro9361]

I think perhaps you might be confusing midbass frequencies with midrange frequency? It's not too easy to get a 6.5 inch midbass to blend all the way up to a tweeters range because that's a large span of frequencies. It's much easier to cross your 6.5 midbass up to your a midrange speaker and then high pass from there up to your tweeter. In other words it's much easier to do a 3 way setup. Hope it helps. Maybe I totally misunderstood your question in which case I should have just shut up and hoped Erin would explain it because hes a master at these things.

[@ABNHW]

Hey Erin, hoping things are looking up for you. When you are back out in KZbin land, this might be a good candidate for an update. Folks said that phase adjustment might fill in the null. would be interesting to see it it does.

[@eldergoose4075]

Is that a 016+ civic hatch? Will be doing my build soon in a mazda 3 hatch. Iirc correctly the dimensions aren't far far off. So you're saying with,subwoofer placement, sub placed on the pas side with the cone firing into the side? How far away? 2-3"? Also, I've always wondered why no one is willing to downfire in a car. I'm very curious as to how that would effect response. 2-3" away from the hatch floor.

[@ErinsAudioCorner]

2019 Hatch. I wouldn't down-fire because it's a waste of space. Not saying you can't or shouldn't. That's just the reason why I don't go that route.

[@ErinsAudioCorner]

2019 Hatch. I wouldn't down-fire because it's a waste of space. Not saying you can't or shouldn't. That's just the reason why I don't go that route.

[@kondrax85]

Hello, thanks for video. Will be more videos from car audio measurements? Will be good if you share us (video), how you filter midbass and subwoofer. Thanks.

[@ErinsAudioCorner]

Yes I will. One day. :)

[@kondrax85]

@@ErinsAudioCorner We waiting for more car videos, almost 2 years :D Please, Please :D

[@carybunker37]

Very good info here, subscribed. Would like to hear your thoughts on adding a front sub to glove box area or passenger footwell?

[@ErinsAudioCorner]

I've had up front subs. I've listened to cars with up front subs. While they have their advantages, they aren't necessarily an all-in-one solution. There are still modal issues caused by the placement and an additional subwoofer in the trunk may still prove beneficial. It's really more car and user dependent, though.

[@simonlebonjnr9561]

Great video. Especially love the Duran Duran t-shirt 😁

[@ErinsAudioCorner]

Thanks, Mr. Le Bon's son!!!! 😀😂👍

[@TaylorFade]

Lol. Why didn't you show us the summed response of the near side midbass + sub?

[@RobertCookcx]

It seems to me that use of all-pass filter to control the lobe location might be another option.

[@chriscuthbertson]

What if the mid bass 50hz - 120hz was mono and in the centre of the dash.

[@thatguy7152]

Thanks for the insight!

[@tombardier]

Cheers. What do you set your crossovers at? 80 lp on sub and 80 hp on the mids?

[@ErinsAudioCorner]

In my personal vehicle the subwoofer filter is set to about 82hz/LR4. On the driver's side door midbass the filter is 92hz/LR8. On the passenger side it is 85hz/LR8.

[@eazy69ful]

what should i crossover my midbass and subs to get it center of dash

[@MrCaptainobvious9999]

Good video, thanks Erin.

[@ChrisProvazek]

@Erin's audio corner , Hey bud great video, are you planning on doing any competing with this car?

[@ErinsAudioCorner]

I do/did. I competed at Finals last year about 5 days after getting it back from the shop that did the install. :D Planned to do some more this year but everything has been canceled or delayed so time will tell.

[@ChrisProvazek]

@@ErinsAudioCorner are you / were you planning on coming down to aggieland?

[@ErinsAudioCorner]

@@ChrisProvazek nah. It's just a tad too far for me. I plan to be at Finals, though.

[@ChrisProvazek]

@@ErinsAudioCorner have you ever been down for it? I swear I feel like I've met you before somewhere. I used to work at mobile toys.

[@ErinsAudioCorner]

@@ChrisProvazek I have not. But maybe we met at another show? I've been to finals nearly every year for the past 10 years.

[@SDX9000]

Great video about the nulls! Note that Dirac ART / Unison is designed to automate the support speaker use. So in OEM systems with Dirac, the null fill-in is normal part of the tuning. Also you did not mention front-subwoofer - seems that "you can't build an SQ car without a front sub" these days :) I was especially impressed with this car, which supposedly only has a front sub: kzbin.info/www/bejne/mqDdpXVsbrWad5Y

[@nakleehayburn9672]

Hey, I put all mid ranges in my car doors (1 per door) and I put tweeters in my doors also (1 per door). But I have no bass, should I use a box with mid basses or should I just get a sub?

[@grasshoppa_6684]

15 or 2 12s

[@dc5001]

By using dual subs, can i fill in the null better, then with 1 single sub. And what benefits does adding dual midbass drivers in the front doors make?

[@ErinsAudioCorner]

You would have to move the speakers at least a foot to really impact the response. Dual woofers up front won't help alter the nulls for the same reason. Think of it like this: an 80Hz sine wave is about 4.3 meters (14 feet). In order for you to effect a change at that frequency for even a 1/4 wave, you would have to move the speakers (or the listening position) 1 meter (~3 feet). The lower in frequency you go, the longer the wavelength is.

[@dc5001]

Would a ported vs sealed sub have the same effectivenes in filling in the near side null in a car?

[@dc5001]

​@ErinsAudioCorner if you moved the sub from the trunk to the rear of the seats behind the front seat, would that of helped the subwoofer play higher into the 60, 70, to 80hz range to fill in the midbass null in your car?

[@bryce6105]

Can the opposite be done to fill the null of your subwoofer at 60Hz? Use the midbass a little boosted at that frequency?

[@ErinsAudioCorner]

It's been a long time since I've tried overlapping electronic filters so I can't say. Every car is different. The obvious concern is that you increase the demand on the midbass. Give it a shot, though.

[@dc5001]

What if you use dual midbass in the doors, or one 6.5 subwoofer in the door next to the mid woofer in the door?.

[@ErinsAudioCorner]

Dual midbass won't do anything to fill in the null. It's placement based.

[@dc5001]

@@ErinsAudioCorner thanks for your reply. I guess maybe the 6.5 in the door could be custom shifted to face more on axis to give a better placement ?

[@bbfoto7248]

@@dc5001 The midbass frequencies that are played by the driver are omnidirectional for the most part, so simply aiming the driver differently will not result in a significant change in response at the listening position. You would need to physically move the driver an adequate distance to another area of the car where it does not produce the same null at your listening position.

[@Alextheampguy]

Setting the crossover at 80hz is something that is common knowledge . I have done that for 20 years. 🤔 cabin gain is something to consider too when you build a system

[@ErinsAudioCorner]

It's funny, when everyone gets in to car audio the standard subwoofer crossover is 80hz. It's the "go to" crossover suggestion. Then as they go further in to the rabbit hole they want "up front bass" so they start buying larger, longer throw woofers and cross lower, but with little benefit. But that doesn't mean people understand why they're doing what they're doing. They just do what others do. At any rate, I didn't say to run the crossover at 80hz. I said to simply use a higher crossover than is typical in car audio circles because the illusion of "up front bass" is due as much to properly filling in midbass nulls as it is the physical location of the drive units themselves. Cheers!

[@Alextheampguy]

@@ErinsAudioCorner you got a new subscriber after that answer. 👍😎

[@ErinsAudioCorner]

@@Alextheampguy sweet!

[@stanbuck7]

Thank you. Nice video. Now I know i'm not insane.

[@ErinsAudioCorner]

Glad to help

[@jsautosolutions]

i tried clicking on your rew tickboxes 🙈

[@buckyflex1]

I literally have my components in the roof inches from my face.lol

[@Alextheampguy]

Can get bether too with making a enclosure for the midbass.

[@ErinsAudioCorner]

An enclosure can't fix placement related problems. Room modes don't care if you use an enclosure. They just care about where you sit, the geometry of the room, and the placement of the speaker.

[@Alextheampguy]

@@ErinsAudioCorner thanks for a good and straight up answer. You really do know what you are talking about. I had to test you alittle . Hehe.

[@Alextheampguy]

Im thinking if you have the option of mounting the midbass under the dash. Firing downwards. Maybe that will help a little . 🤔

[@ErinsAudioCorner]

@@Alextheampguy I try to shoot straight when I feel it's appropriate. Thing about car audio, though, is there aren't really a lot of certainties but there are some things you can always count on like room modes kicking your butt! haha

[@ErinsAudioCorner]

@@Alextheampguy I considered that for my new car. For the time being I'm using the door locations but I'd like to go kicks or like you said, mount the midbass in the dash. Mainly the latter just so they're out of the way. I used to have 10's in my kicks. It was fun. But not really what I want anymore.

[@sLAYtheday33]

Home alone. Anyone else out there who did it with him?

[@MaximusOpus]

Almost everything is correct what he says until u make custom enclosure dedicated to manufacture specs for your midbass !!! Huge improvement

[@bbfoto7248]

@Max Max Not really. The 6.5 midwoofers that Erin is using are designed for excellent midbass response in IB of standard car doors. And he has done quite a bit to control any door or panel resonances. The real issue he is discussing is a result of the LOCATION or placement of the driver in the vehicle in relation to the listening position. Adding an enclosure doesn't change that aspect. See Erin's response below to @Alextheampguy

[@bertall1ca]

I don't have any crossovers, just the factory speakers for now but this video ---> kzbin.info/www/bejne/nmSoiah-oaesaq8 helped out before adding a subwoofer

[@johnviera3884]

“Moving subwoofers around” lol If you have space to move a subwoofer around, you are leaving bass on the table.