DiyMobileAudio.com Car Stereo Forum banner
1 - 20 of 28 Posts

·
Moderator
Joined
·
18,696 Posts
Discussion Starter · #1 · (Edited)
In this video I discuss why I recommend using your subwoofer to improve midbass response. Get your pitchforks ready!... I’m suggesting to run your sub higher than 30hz! :D

This isn’t truly a shocking revelation. Plenty of people already do what I suggest. It just goes against intuition and against some beliefs in the car audio community that a subwoofer should not play too high in frequency because it can cause the bass to be localized behind you.

The reason why is due to one MAJOR issue in car audio: the “Nearside Null”. This is the large dip in response of the driver’s side midbass speaker that occurs typically in the 70-90hz region. This doesn't occur in every car; there are certainly exceptions to the more extreme car installs.


It is an acoustical null caused by the relationship of the listener’s location relative to the midbass location and generally caused by the width of the vehicle. If you play a track with bass guitar it’s very prevalent; you get a localization to the nearside midbass speaker when the midbass speaker is crossed lower than the frequency where the null occurs.

Generally speaking, the lower your crossover point between midbass and subwoofer, the more noticeable this occurrence is. Unfortunately, this isn’t something you can simply “EQ out”, either. Throwing +6dB at this null may only result in 1dB of actual gain; that means you’re wasting a LOT of power and risking damage to your speaker for no acoustical gain. Some of you may even think to yourselves “seems like you’re not getting much by crossing the midbass low. Maybe there’s not as much benefit as I thought in doing that”. That’s a logical assumption and a lot of times that’s actually true. Crossing the midbass too low can actually result in more “bass behind you”! And you can also take some of the strain off your midbass by crossing them at or above the null. Ironically, we in car audio tend to cross midbass low to get the “up front” bass we so much desire. BUT, IN FACT, the majority of the time you have bass that pulls to the rear is BECAUSE of the midbass nulls. I know that sounds counteractive. But it’s the truth. Standing waves are problematic and this is one symptom of them; whether in home or car audio.

Contrary to popular belief, raising the subwoofer crossover in to the region that this null occurs can actually HELP the sound to stay focused and achieve “up front” bass. If you can move your subwoofer to a location where it is null-free through a frequency above the Nearside Null then you can likely improve midbass without negatively impacting the “up front bass” effect that so many are after. And you can also take some of the strain off your midbass by crossing them at or above the null frequency. Not all have the luxury of space to move the subwoofer around much but experimentation is key here; you may be surprised at the difference subwoofer placement in the trunk can make.

And one important conclusion here is that placing the rear mounted subwoofer on the opposite side of the listening position often results in better response!

 

·
Registered
Joined
·
3,032 Posts
I've always been a big fan of this approach. When I first arrived at this site I tried going active and crossing my mids low. I noticed that it impacted my mid-range and the happy spot seemed to be steep slopes around 80hz to 90hz.

In the end, I found that a passenger rear trunk sub gave me the best performance overall. I couldn't ever make enough sense of my logic to post though. I really appreciate all the work you put in to the site.

Matter of fact, this thought process almost led me to try and replace my mids with stereo subs in my rear deck for a 3-way setup

Sent from my Pixel 4 XL using Tapatalk
 

·
Moderator
Joined
·
18,696 Posts
Discussion Starter · #3 ·
I really appreciate all the work you put in to the site.
Thanks. I'm working on getting my test setup going again. I am also going to be testing loudspeakers and doing reviews on them as well in the same format. But I plan to keep trying to do these "educational" type videos as often as I can to help people who struggled with the same stuff I did for years.
 

·
Registered
Joined
·
3,032 Posts
These videos are great. It took me a long time to fully comprehend some of the concepts and I'm still learning a lot. I think that's one of the reasons diyma gets a bad wrap. A lot of this information is hard to communicate.

These threads should by sticky'd! Let's keep donating to Erin too guys

Sent from my Pixel 4 XL using Tapatalk
 

·
Registered
Joined
·
768 Posts
The last video, I found myself thinking of how I have always tuned like that, just didn't realize WHY I like it that way !
 

·
Registered
Joined
·
107 Posts
So what happens when you move the front midbass crossover point higher? e.g: going from 60Hz high pass up to something like 100Hz high pass? Would using a second order slope improve things if the filtered band is now 180* out of phase? A shallower slope starting from a higher crossover point should still leave a significant amount of energy going to the midbass at 80Hz, but still have enough effect on cone control at low frequencies.

I've been fighting this for a while in my C6 Corvette. Sub placement had a big impact on bass presence due to cancellation from the cabin geometry. I found the best answer was to move the sub(s) from the rear corner(s) of the hatch forward to right behind the driver/passenger shoulders, but I still have a relatively soft midbass response considering the power and speaker selection. Door speaker locations are not up for change, so finding other ways to minimize losses like this sounds good.
 

·
Registered
Joined
·
519 Posts
Thanks for posting this video. Since I put my subwoofer up front it has given me the ability to do, with much success, exactly what you are talking about. My car has the exact left side dip you reference. It is at 75hz and is about 6db.
Moving the sub crossover from 50hz to [email protected] and shifting the mid bass HP from 80hz to [email protected] has totaly center the bass in the car. It hits hard and center, no pulling left. Also raised the LP on the mid basses which has also improved the impact and clarity of the system.
 

·
Registered
Joined
·
1,023 Posts
Erin, Any input on which way the sub faces? When I place facing the back obviously I get more impact. But when faced towards front the bass seems better and easier to blend but the impact goes way way down.
 

·
Registered
Joined
·
2,469 Posts
Erin, Any input on which way the sub faces? When I place facing the back obviously I get more impact. But when faced towards front the bass seems better and easier to blend but the impact goes way way down.
Sub loading will change the response of the sub a little, it’s normally one way or the other sounds better 👍🏼
 

·
Registered
Joined
·
2,469 Posts
To further illustrate this point about phase and doors...

275917


that is a phase measurement in smaart with 1/12 smoothing, if you see the green line and how it wraps around at 80hz you can’t possibly cross that to a sub at 80hz and get phase coherence due to the massive room mode influence at the listening position

then to show a different mounting, this is my hybrid u69v2 in the floor nestled just under the front edge of my seat IB

275918


that is what you want phase to look like, even with the small blip at 160 and 220 on opposing sides you can see that the phase (And timing also) is largely identical so I get 6db of summation and perfect phase coherence for the most part 👍🏼 It also includes the almost perfect transition to my mids from the midbass where the phase matches perfectly to over 1k where there is a slight wrinkle and then on up...
 

·
Registered
Joined
·
1 Posts
To further illustrate this point about phase and doors...

View attachment 275917

that is a phase measurement in smaart with 1/12 smoothing, if you see the green line and how it wraps around at 80hz you can’t possibly cross that to a sub at 80hz and get phase coherence due to the massive room mode influence at the listening position

then to show a different mounting, this is my hybrid u69v2 in the floor nestled just under the front edge of my seat IB

View attachment 275918

that is what you want phase to look like, even with the small blip at 160 and 220 on opposing sides you can see that the phase (And timing also) is largely identical so I get 6db of summation and perfect phase coherence for the most part 👍🏼 It also includes the almost perfect transition to my mids from the midbass where the phase matches perfectly to over 1k where there is a slight wrinkle and then on up...
Hi, i've tried to use Smaart V8 to check phase alignment but im not able to get the measurements like yours. Mine only shows straight lines on the transfer function window. Im using behringer ecm8000 mic and um2 and connected to my helix dsp pro mk2 via rca inputs.
 

·
Registered
Joined
·
2,469 Posts
Hi, i've tried to use Smaart V8 to check phase alignment but im not able to get the measurements like yours. Mine only shows straight lines on the transfer function window. Im using behringer ecm8000 mic and um2 and connected to my helix dsp pro mk2 via rca inputs.
Post pics on a fresh thread and I’ll see if I can help 👍🏼
 

·
Premium Member
2015 VW Passat TDI w/ Stage-2 Tune
Joined
·
387 Posts
I took your advice. I had my door speakers crossed at 60Hz/24db and sub crossed at 90Hz/24db because I wanted more midbass, but was never happy with it. Sounded sloppy. Changed them both to 80Hz/24db and the whole thing came alive! Thanks!!
 
  • Like
Reactions: ErinH

·
Registered
Joined
·
543 Posts
now move the sub low pass down to 60Hz. That should clean things up even further and will also allow the accoustical crossover to stay close to 80Hz when you turn the volume up.
 
  • Like
Reactions: bnae38

·
Registered
Joined
·
5 Posts
great thread mr OP! im subscribing! next thing you will talk about is attenuating into the mid and building some bass trap(s).
 

·
Registered
Joined
·
57 Posts
I took your advice. I had my door speakers crossed at 60Hz/24db and sub crossed at 90Hz/24db because I wanted more midbass, but was never happy with it. Sounded sloppy. Changed them both to 80Hz/24db and the whole thing came alive! Thanks!!
Shop has mine set at. Sub at 80htz. Mids at 70 htz. I need to look at changing mine getting some real
Odd sounds at certain frequencies. Perhaps that is why.
 

·
Premium Member
2015 VW Passat TDI w/ Stage-2 Tune
Joined
·
387 Posts
now move the sub low pass down to 60Hz. That should clean things up even further and will also allow the accoustical crossover to stay close to 80Hz when you turn the volume up.
What do you mean by acoustical crossover?
 

·
Registered
Joined
·
2,469 Posts
What do you mean by acoustical crossover?
Where they actually crossover... the number in the dsp is not relevant to real life due to the level of the sub being higher... the audiofrog guide does provide a good explanation for this with pictures of responses to demonstrate what is being referred to 👍🏼
 

·
Moderator
Joined
·
18,696 Posts
Discussion Starter · #20 ·
now move the sub low pass down to 60Hz. That should clean things up even further and will also allow the accoustical crossover to stay close to 80Hz when you turn the volume up.
Careful... That could also defeat the entire purpose of my initial suggestion and may leave him with a "hole" in the response. You can try it. Just don't expect that it will absolutely work. That's just part of this hobby. Lots of variables. But try and see.
 
1 - 20 of 28 Posts
Top