# Under seat midbass



## Dan750iL (Jan 16, 2016)

Are there any disadvantages? If I do this I'd be able to lowpass at or maybe a little below 300hz.


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## Bayboy (Dec 29, 2010)

As long as your midrange drivers can dig deep enough to mate with it, you'll be okay. 

Sent from my SM-G955U using Tapatalk


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## EmptyKim (Jun 17, 2010)

Maybe tactile feel of the underseat drivers


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## ManBearPig (Jul 18, 2016)

If I had the room for underseat midbass enclosure, I would have done it already.
Beats the hell out of rattling doors


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## Bayboy (Dec 29, 2010)

ManBearPig said:


> If I had the room for underseat midbass enclosure, I would have done it already.
> Beats the hell out of rattling doors


It's all tradeoffs. My usual remedy for rattling doors is to get away from lower Q drivers that seem to be so prevalent in the DIY hobby. Now if you want to do enclosures, a lower Q driver would probably be better due to low airspace requirements. Then there's the tradeoff of advantages/disadvantages of off-axis response beyond the crossover point. But that's another story


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## mattkim1337 (Jan 31, 2018)

Wouldn't you also lose proper stereo imaging in the midbass frequency range?


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## Jimbo2032 (Mar 8, 2017)

I'm thinking about a similar application, but don't have a lot of experience in this arena. Is this for a 3-way setup with subs?


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## Dan750iL (Jan 16, 2016)

mattkim1337 said:


> Wouldn't you also lose proper stereo imaging in the midbass frequency range?


Not sure. That was part of the reason I asked.



Jimbo2032 said:


> I'm thinking about a similar application, but don't have a lot of experience in this arena. Is this for a 3-way setup with subs?


It is. I believe in a two way the midbass would have to play way too high to be effective under the seats unless you had a mid/tweeter that could hit crazy low.


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## mattkim1337 (Jan 31, 2018)

You would be able to hear the notes fine, but your ability to localize the midbass sounds in your soundstage would be compromised. I suppose if you have one driver under each of the front two seats, you would be able to perceive the right side as right on your soundstage. However, the left side midbass notes under your seat would be perceived as being closer to center on your stage, rather than left, as the sound will reach both your ears at the same time, and also be the same volume level to both ears. In a door, the left speakers would be biased towards your left side in terms of volume and location. 

For example, if a song is recorded with the bass guitar player on the far left, you would hear his guitar playing more skewed towards the center of your stage. Depending on where your midrange is located, it could help pull the bass guitar out left again, but I'm not 100% sure. 

All of this is conjecture, so if anyone could chime in that would be helpful!


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## Dan750iL (Jan 16, 2016)

I would be mounting one under each seat.


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## mattkim1337 (Jan 31, 2018)

Do you have time alignment available, and are you running active or passive?


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## Dan750iL (Jan 16, 2016)

mattkim1337 said:


> Do you have time alignment available, and are you running active or passive?


It'll be active. I haven't installed anything yet so I have no real numbers. Just looking for experiences and pitfalls if I go this way. I had been planning on putting them (JL ZR800s) in the doors but the cavern under the seats of my 17 Explorer will accommodate probably close to a .5 cube box. Want to explore the option before I start installing.


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## EmptyKim (Jun 17, 2010)

Lots of BMW drivers do this as there are factory 8s under the seats, 4" in the door and 1" tweeter in the sail. 

When I did time-alignment, I had to do manual adjustments for the underseat woofers. It was vastly different than when I did the tape measure route.


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## Dan750iL (Jan 16, 2016)

EmptyKim said:


> Lots of BMW drivers do this as there are factory 8s under the seats, 4" in the door and 1" tweeter in the sail.
> 
> When I did time-alignment, I had to do manual adjustments for the underseat woofers. It was vastly different than when I did the tape measure route.


That's what I'm looking at. The ZRs under the seats with GB40s and GB10s in the OEM speaker locations in the doors. Otherwise it'll be ZRs in the doors with GB25s and 10s in the location where the OEM tweeters are now. A lot more fabrication this way.

So just took some more tuning to get it right but you got there?


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## EmptyKim (Jun 17, 2010)

Dan750iL said:


> That's what I'm looking at. The ZRs under the seats with GB40s and GB10s in the OEM speaker locations in the doors. Otherwise it'll be ZRs in the doors with GB25s and 10s in the location where the OEM tweeters are now. A lot more fabrication this way.
> 
> So just took some more tuning to get it right but you got there?


Yes. But I'm definitely not a tuning guru.


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## banshee28 (Mar 23, 2006)

Yea, luckily I have stock underseat locations (BMW) and really like them. I have them playing from ~50Hz to 225 or so (Still tuning), and they are mostly TA'd, and seem mostly "up front".

However, I listed to some cars during the last SBN event, and even though my MB is similar to those, you really can localize 8"Midbass in Kick's quite a bit easier on the stage (where they should be) with kicks vs underseats. I still have some tuning to go, but like mentioned before there are some tradeoffs. For me unless I did dedicated MB kicks, I will definitely keep what I have and tune them as much as I can.


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## Patrick Bateman (Sep 11, 2006)

I've tried my midbasses in about a dozen locations. Under the seat is probably my favorite. It's where I have the midbasses currently:

http://www.diymobileaudio.com/forum/5265514-post88.html

I tried them on the rear deck, a la Richard Clark, but the depth was a bit compromised. It wasn't bad at all, but it wasn't great.

I tried them in the doors, and that works alright. I'm not a big fan of putting speakers in the stock locations because I like to maintain as much value in my car as possible, and ripping out the stock stereo is a great way to reduce the value of the car. Particularly if you're ADHD like me and you change your stereo every three months.

I tried them under the gas pedal, that worked well, the stage is a little narrow though.

I tried them under the seat, I think I like that the best. The key is that you want to use bandpass midbasses. By going bandpass you can move the port all the way to the edge of the vehicle, which maintains stage width. (See the post I linked.)


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## robtr8 (Dec 6, 2011)

The GB40's can go down to 100Hz.


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## hdrugs (Sep 7, 2009)

This may look funny but since I have carpeted and put a grill on 

7-8 litres of volume

Now running scanspeak 18wu 

About 2 year ago the strongest midbass I used were the hat Clarus and the the best sounding was the esotar 650 

I deadened the doors to point where they were heavy opening and closing and still even the tm65 even at half power caused rattle

Since moving away from doors to sealed enclosure I've gain higher quality bass then esotar and protential outputs which exceed the tm65 best of all no rattles


It would be nice if I had space underseat


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## Bayboy (Dec 29, 2010)

I'd be cautious of enclosing the ZR800-CW as they are a fairly high Q driver meant to be in an IB door. Erin's test shown them to be much higher than JL states so you might want to consider something else that will be a little less robust in that airspace and there should be plenty to choose from.

http://medleysmusings.com/zr800cw/


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## GreatLaBroski (Jan 20, 2018)

Yeah those JLs are very stiff for IB. I wonder if a pair of these per box would work out: https://www.madisoundspeakerstore.com/flares/ports/vents/scanspeak-290001-aperiodic-vent-ssv/#tab-1


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## Bayboy (Dec 29, 2010)

They're ok (tried them before), but the results aren't as accurately targeted like choosing a more appropriate driver. Skizer has had good results with these and IIRC, considers them his favorite for enclosed midbass. Suggested airspace is right at target though I think he might have gone smaller (.35?) and still liked them. 

https://www.madisoundspeakerstore.com/approx-8-woofers/scanspeak-22w/4534g-discovery-8-woofer-4-ohm/


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## Dan750iL (Jan 16, 2016)

Bayboy said:


> I'd be cautious of enclosing the ZR800-CW as they are a fairly high Q driver meant to be in an IB door. Erin's test shown them to be much higher than JL states so you might want to consider something else that will be a little less robust in that airspace and there should be plenty to choose from.
> 
> http://medleysmusings.com/zr800cw/


Modelling them in WinISD the response didn't look too bad highpassed at 80hz. I have also been looking at ways to vent them into the frame.

Still undecided.


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## Bayboy (Dec 29, 2010)

Dan750iL said:


> Modelling them in WinISD the response didn't look too bad highpassed at 80hz. I have also been looking at ways to vent them into the frame.
> 
> Still undecided.


Which specs did you use, JL's or the ones tested on Medley's Musings?


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## Dan750iL (Jan 16, 2016)

Bayboy said:


> Which specs did you use, JL's or the ones tested on Medley's Musings?


LOL

Just got finished putting the MM specs in. That does ugly it up quite a bit. May still try to vent them into the frame for additional airspace.


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## Bayboy (Dec 29, 2010)

Dan750iL said:


> LOL
> 
> Just got finished putting the MM specs in. That does ugly it up quite a bit. May still try to vent them into the frame for additional airspace.


That's probably going to be your best bet if you stick with them. Someone else tried to enclose them in kicks and wound up swapping to a set of RS225-4 (not sure if it was the P series), but had much better results in the end. Said the ZR's were choked badly. They really should be IB.


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## hdrugs (Sep 7, 2009)

I don't think good to seal the zr


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## GreatLaBroski (Jan 20, 2018)

Yeah the ZR’s are designed for IB based on their suspension compliance / dampening.


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## mitchyz250f (May 14, 2005)

How much distance is needed between the midbass and the bottom of the seat?

Also since the bottom of the seam is 4 inches of foam would you get more performent by having the bottom of the seat covered in plywood or fiber glass?


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## SPLEclipse (Aug 17, 2012)

You need as much room as you can to clear the cone travel. I'd say at least 1/2".

Adding a rigid surface wouldn't make much of a difference at lower frequencies. Above a few hundred hz is where you'd start to get absorption issues.


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## Patrick Bateman (Sep 11, 2006)

mitchyz250f said:


> How much distance is needed between the midbass and the bottom of the seat?
> 
> Also since the bottom of the seam is 4 inches of foam would you get more performent by having the bottom of the seat covered in plywood or fiber glass?


Waves have a way of moving around an object.










For instance, a 10khz wavelength is 3.4cm long. The phase plug in front of the dome is virtually invisible, because it's a fraction of a centimeter. If it was two or three centimeters in diameter, the phase plug would be a problem.










A 100hz wavelength is 3.4 meters long. The seat in front of the midbass is virtually invisible because it's a fraction of a meter. If it was two or three meters in diameter, the seat would be a problem.


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## mitchyz250f (May 14, 2005)

Thanks Patrick I was hoping you would respond. I remember reading that the B&C 8NDL51 that you use for mid-bass only went down to 160 but in the car it got down to 100Hz. So let's say I wanted to go sub-less, had room for a .7 cu/ft enclosure and the mid-bass only had to work down to 35 - 40Hz (I am much more interested in snappy mid-bass than sub bass) in the car; what you recommend? Can't be more than 5" deep but I could go up to a 12" and port. Any suggestions?

Maybe the B&C 8NDL51 ported in an oversize enclosure?


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## Patrick Bateman (Sep 11, 2006)

mitchyz250f said:


> Thanks Patrick I was hoping you would respond. I remember reading that the B&C 8NDL51 that you use for mid-bass only went down to 160 but in the car it got down to 100Hz. So let's say I wanted to go sub-less, had room for a .7 cu/ft enclosure and the mid-bass only had to work down to 35 - 40Hz (I am much more interested in snappy mid-bass than sub bass) in the car; what you recommend? Can't be more than 5" deep but I could go up to a 12" and port. Any suggestions?
> 
> Maybe the B&C 8NDL51 ported in an oversize enclosure?


8NDL51 in a 0.43cf vented box has an F3 of 69Hz

So it's well suited to that application.

But why go subless?

Note that there's nothing wrong with having a vented midbass and a sealed sub, or even a vented midbass and a vented sub. As long as you have some measurement equipment and you set the crossover slopes carefully, it works fine. Richard Clark had vented midbasses.


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## lankfordcodi (Apr 28, 2020)

Patrick Bateman said:


> I've tried my midbasses in about a dozen locations. Under the seat is probably my favorite. It's where I have the midbasses currently:
> 
> New Way to Increase Soundstage Depth
> 
> ...


Oh my god where is the link? I just realizd what I’m going to be spending the next 10 weekends of my life doing. I’m so tired of my doors rattling and not getting the mid bass I want, blowing expensive sets of components. I’m going to band pass between 60hz and may be 200hz under my seats!!! I measured and I have exactly 4 inches to work with. What kind of drivers are you using? I will have to build the enclosures myself but I need some kind of 8 inch woofer with a 2.5” inch depth or less


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## I800C0LLECT (Jan 26, 2009)

80Hz to 200Hz worked great for me. 300Hz started to hurt the imaging when turned up louder. Anything below 80Hz and the tactile feedback started.

Nobody ever knew I had sealed mids under the seats

Sent from my Pixel 4 XL using Tapatalk


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