Too much loose mid bass in 2016 CX9 Bose stereo - quick improvement

jgriffter

Member
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2016 Mazda CX-9 Signature
I like the Bose stereo in the new CX9 but the bass is overpowering in the mid-bass, drowning out a lot of the detail in the music. Adjusting the bass control doesn't do a lot - you either have too much or you have too little by bumping down the control too far.

I had a similar problem in my Ford F150 Sony stereo sub and used a simple remedy to help improve things. The Bose sub is in the rear over the spare tire. I pulled it out and took it apart, undoing the screws that hold the cover plate on, then the screws that hold in the single sub speaker. I put polyfill from a pillow in the space under the sub - not packing it in, just covering all the inside space with a 1 inch or so layer of the polypill. I put everything together and tested it out. While I still have the overly thumpy mid-bass, the polyfill did tone it down quite a bit and cleared up the rest of the music by not overpowering it. The low bass is still there - this affects mostly the drone you hear at certain frequencies. It is not a total cure but it helps. If you are thinking your system sounds the same way it is an easy 20 minute improvement you might like.
 
I've read about this on the F150 forums. I need to get some of this polyfill and try it in my truck.
 
poly fill is used in the speakers boxes to dampen it's woofer for more taut and better controlled bass... good idea, thanks
 
I like the Bose stereo in the new CX9 but the bass is overpowering in the mid-bass, drowning out a lot of the detail in the music. Adjusting the bass control doesn't do a lot - you either have too much or you have too little by bumping down the control too far.

I had a similar problem in my Ford F150 Sony stereo sub and used a simple remedy to help improve things. The Bose sub is in the rear over the spare tire. I pulled it out and took it apart, undoing the screws that hold the cover plate on, then the screws that hold in the single sub speaker. I put polyfill from a pillow in the space under the sub - not packing it in, just covering all the inside space with a 1 inch or so layer of the polypill. I put everything together and tested it out. While I still have the overly thumpy mid-bass, the polyfill did tone it down quite a bit and cleared up the rest of the music by not overpowering it. The low bass is still there - this affects mostly the drone you hear at certain frequencies. It is not a total cure but it helps. If you are thinking your system sounds the same way it is an easy 20 minute improvement you might like.

Can you send a pic to what it looks like?
 
Can you send a pic to what it looks like?

Here you go. Easy disassembly.
feb9484f6b82b85a5085843857ddcd4b.jpg



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Good plan; I'll give it a try. I really dislike the quality of the Bose bass in this car. Too much quantity, way too little quality. I want the bass to sound like a solo piano low note or a solo string bass low string, about 30 hz, where I can hear the vibrations of the strings. Not the vibration of the car interior panels. Real music doesn't have low notes that are boomy.

Buy a small bag of polyfill at any place that sells sewing supplies, or a used pillow at Goodwill, or pick up after the dog disembowels another new teddy bear.

I found this on the interwebs, "The sound wave coming off the back of your subwoofer [speaker cone] reacts with the air contained in the box. Polyester fiber stuffing slows down sound waves inside the box, making the subwoofer perform as if the box were bigger."
 
Good plan; I'll give it a try. I really dislike the quality of the Bose bass in this car. Too much quantity, way too little quality. I want the bass to sound like a solo piano low note or a solo string bass low string, about 30 hz, where I can hear the vibrations of the strings. Not the vibration of the car interior panels. Real music doesn't have low notes that are boomy.

Buy a small bag of polyfill at any place that sells sewing supplies, or a used pillow at Goodwill, or pick up after the dog disembowels another new teddy bear.

I found this on the interwebs, "The sound wave coming off the back of your subwoofer [speaker cone] reacts with the air contained in the box. Polyester fiber stuffing slows down sound waves inside the box, making the subwoofer perform as if the box were bigger."

Yes it is an old trick but it often works. Used it several times for bass cabinets when playing over the years. If you can remove some of the thumps mid-bass, it uncovers some of the detail in the music - just doesn't overpower it as much. Good luck.


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Thanks for this. Ill give it a try. That's my biggest gripe with this audio system. That and the active noise cancellation sometimes gives me a headache
 

I stuffed some polyfill from an old pillow into the housing, and it made an immediate improvement. I'll re-do the job and do it better. I ordered new, not pre-compressed, polyfill from Parts Express and also ordered Sonic Barrier vinyl sound damping sheet material. Parts Express is a great go-to place for electronic parts and accessories to the audio/video industry, good quality and good prices.

The pic shows the speaker assembly with the top cover removed. The back side of the driver cone (bottom) pushes air in the space with the polyfill and the sound exits through the duct that wraps about 12" around the inside of the enclosure. The front side (top) of the cone pushes air against the top cover and the sound exits in the 1/8" peripheral gap around the top cover. One big problem is the resonance of the enclosure's flat surfaces. We want all the sound to come from the driver cone surfaces. We do not want the enclosure surfaces moving and pushing more sound to us. That is a big source of fuzzy sound. If the enclosure is moving, your sound quality is degraded, big expensive speaker or small cheap speaker. I'll use the Sonic Barrier stuff to stick on the flat surfaces of the bottom of the enclosure, the top surface shown in the picture, and the top of the cover. The best product I've found for this for home speakers is G-R Research No Rez, but it's too thick for this application. You can greatly improve almost every home speaker by sticking No Rez to all interior surfaces (install wood braces to big surfaces where possible) and lightly fill the space with polyfill.
 
Big improvement.

I think the main problem is resonance from the housing. Access the sub and put your hand on the housing while it plays. There should be NO vibration from the housing. We want all the sound to be from the speaker cone pushing sound waves through the air to our eardrums. We do not want the speaker housing pushing sound waves to us--that's distortion.

I applied Parts Express Sonic Barrier damping sheet (three 10"x13" sheets) to the bottom, sides, mid surface, and top surface. Parts Express is a good go-to place for audio & video parts and equipment. Sonic Barrier is thin (good here) but doesn't quite do a 100% job; a slightly thicker product might work better. I also lightly fully filled the lower compartment with polyfill (not tightly, just lightly filled) and cut a piece of fiberglass furnace filter material to fit under the top plate.

The result is nice. The lower notes of a piano sound like...like a piano. Other low notes sound good, not muddy or boomy.
 
I stuffed some polyfill from an old pillow into the housing, and it made an immediate improvement. I'll re-do the job and do it better. I ordered new, not pre-compressed, polyfill from Parts Express and also ordered Sonic Barrier vinyl sound damping sheet material. Parts Express is a great go-to place for electronic parts and accessories to the audio/video industry, good quality and good prices.

The pic shows the speaker assembly with the top cover removed. The back side of the driver cone (bottom) pushes air in the space with the polyfill and the sound exits through the duct that wraps about 12" around the inside of the enclosure. The front side (top) of the cone pushes air against the top cover and the sound exits in the 1/8" peripheral gap around the top cover. One big problem is the resonance of the enclosure's flat surfaces. We want all the sound to come from the driver cone surfaces. We do not want the enclosure surfaces moving and pushing more sound to us. That is a big source of fuzzy sound. If the enclosure is moving, your sound quality is degraded, big expensive speaker or small cheap speaker. I'll use the Sonic Barrier stuff to stick on the flat surfaces of the bottom of the enclosure, the top surface shown in the picture, and the top of the cover. The best product I've found for this for home speakers is G-R Research No Rez, but it's too thick for this application. You can greatly improve almost every home speaker by sticking No Rez to all interior surfaces (install wood braces to big surfaces where possible) and lightly fill the space with polyfill.


i'm assuming you bought the 1lb bag of polyfill from parts express? how much of it was needed for the sub? the whole bag?
 
Big improvement.

I think the main problem is resonance from the housing. Access the sub and put your hand on the housing while it plays. There should be NO vibration from the housing. We want all the sound to be from the speaker cone pushing sound waves through the air to our eardrums. We do not want the speaker housing pushing sound waves to us--that's distortion.

I applied Parts Express Sonic Barrier damping sheet (three 10"x13" sheets) to the bottom, sides, mid surface, and top surface. Parts Express is a good go-to place for audio & video parts and equipment. Sonic Barrier is thin (good here) but doesn't quite do a 100% job; a slightly thicker product might work better. I also lightly fully filled the lower compartment with polyfill (not tightly, just lightly filled) and cut a piece of fiberglass furnace filter material to fit under the top plate.

The result is nice. The lower notes of a piano sound like...like a piano. Other low notes sound good, not muddy or boomy.

I think your 100% right about the housing. Most of the factory sub housings tend to be made from a cheaper plastic and don't have enough rigidity. I'm going to do what you did with the dampining sheets but maybe more so. Maybe even put it on the outside too to try to re-inforce the housing even more. Of course, with all the time in the world one could even make a custom box to fit in the same area.
 
Big improvement.

I think the main problem is resonance from the housing. Access the sub and put your hand on the housing while it plays. There should be NO vibration from the housing. We want all the sound to be from the speaker cone pushing sound waves through the air to our eardrums. We do not want the speaker housing pushing sound waves to us--that's distortion.

I applied Parts Express Sonic Barrier damping sheet (three 10"x13" sheets) to the bottom, sides, mid surface, and top surface. Parts Express is a good go-to place for audio & video parts and equipment. Sonic Barrier is thin (good here) but doesn't quite do a 100% job; a slightly thicker product might work better. I also lightly fully filled the lower compartment with polyfill (not tightly, just lightly filled) and cut a piece of fiberglass furnace filter material to fit under the top plate.

The result is nice. The lower notes of a piano sound like...like a piano. Other low notes sound good, not muddy or boomy.


So I finally got some time to work on the subwoofer a bit more. I started this thread with the polyfill suggestion. PT guy recommended deadening the sub cabinet with auto sound deadened material so I took a shot at that today.

I took the sub out and covered the cabinet with sound deadener -
65b820f5b83a22f8cc1cce4f42a46faf.jpg


I was going to do the inside of the top plastic piece that faces the speaker but in taking a look at it, the surface is textured and not good for deadener.
16d874193ad5e050194f685eb98ca6ad.jpg


I did all the surface areas including the bottom. The different angles and shape of the sub made it take a little longer but working with the deadener is pretty easy. Here is the bottom.
144ba95b84b28d9b834c11bdd947dc01.jpg


Installed the sub back in the car.
4f365b6a86b16c0127580bf3e7c2f477.jpg


So how did it work out? Very well. The deadener took most of the boominess and false bass out of the sub. The sub has a sharper attack and the bass notes are much clearer. Instead of just hearing the thud of the bass you actually hear the note and the bass strings as well. Low volume music has bass that you can differentiate the notes. The mids cleared up as well since they are not being drowned out by the boomy bass.

The polyfill and sound deadener make a great difference in the clarity and liveliness of the Bose stereo. If you are thinking the stereo sounds muffled and boomy, this is a simple fix that has real results. Good luck!




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For those without a bose system, is there an offering available to connect a sub in similar fashion by the spare tire?
 
If you are familiar with handmade things, I made one there for other cart with fiberglass and resin. Also you can find a tutorial here in CX-9 section for some similar idea in the side of the trunk. I think you have to think on a different way to keep the box in the weell, but with some lines could be attached good there. Saludos
 
Did this mod yesterday with fiberfill and Dynamat of the outside. Sounds better but still a little boomey, but better.
 
Just did the outside of mine with Boom Mat and used a bit over three 12"x12.5"x2mm sheets. A considerable improvement! Bass is just a bit boomy still at certain frequencies, but overall it's a lot tighter sounding. It improved so much that "muddiness" has gone away from the subwoofer and now I'm hearing the front door panels rattle
(argh)

Anyone know of a tutorial/write-up on how to remove the front door panels?
 
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