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Discussion Starter · #1 ·
Hi There,

I installed Sound proofing last weekend in my doors and I was hoping it would help with the midbass. But with my current speakers it seemed to decrease midbass somehow. I installed the Knu Konceptz Kolosso edition vibration dampener on the outer door skin, inner skin, and the back of the door panels. I then used STP SPL08 on the outer skin. Blackhole Tile on the inner skin(in the door) around the window motor and everywhere I could get it, I then finished up the door panels with STP BTP08. The door was pretty much vented since the stock liner was coming off. Now it is sealed.

I have noticed a decrease in midbass. I am running 100 watts to each door. Since the door is now sealed, is it putting more resistance on the speaker? Will I need a bigger amp to get the same output? I am going to upgrade my speakers to the Illusion Audio C6. I don't want to be disappointed when I install them and they are lacking midbass since my amp is to small.

Any idea if this could be happening or is it something else?
 

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Have you tried to EQ it back in?
 

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Discussion Starter · #3 ·
Not yet. I'm actually saving up for a mosconi 6to8. When I turn the base up on the HU (MX406) it still sounds crappy. Like I have a 4" in there lol

Is the lack of an eq causing the problem?
 

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First question would be, did you accidentally get the polarity of the speakers wrong on one side when you reinstalled them?

Second thought would be, maybe you had a resonance in the door before that was augmenting your midbass output and now that resonance is dead?
 

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maybe its the lack of resonance that your hearing

edit: beat me to it joey.
 

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First question would be, did you accidentally get the polarity of the speakers wrong on one side when you reinstalled them?

Second thought would be, maybe you had a resonance in the door before that was augmenting your midbass output and now that resonance is dead?
maybe its the lack of resonance that your hearing

edit: beat me to it joey.
Thrice.

Resonance queues are gone.


Bret
PPI-ART COLLECTOR
 

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Discussion Starter · #8 ·
The polarity is all correct. I don't really have a clue what could be going on or the first step to attempt a fix. Maybe eq first?
 

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That's a good starting point.

What are the crossovers set at?
 

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If it really is that bad, try flipping polarity of one of the speakers at the amp (easiest point) just to see...
 

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I've wondered why the original stock speakers can have more bass even with all the holes and untreated surfaces- than very good aftermarket speakers when the door is treated / sealed.

i have modeled many drivers using the door as a volume sealed enclosure.

the fact is that many drivers have a higher F3 (bass drop off frequency) when they are enclosed- essentially causing them to produce less bass when sealed.

Therefore some drivers need to be vented back into the cabin to have a lower F3 and produce more bass.

TRY TO OPEN A 3" DIAMETER VENT IN YOUR TREATMENT AND REPORT BACK IF THIS IMPROVED YOUR BASS RESPONSE.
 

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Stock speakers usually have very high Q (like 0,7-1,0) which gives you a bump in FR around Fs of the driver. This gives you bass. The resonance of the door panel is distortion, distortion adds to the fundamental and gives the illusion of... again; more bass. Aftermarket mids are NOT designed to act like subs, they have usually lower Qt than stock drivers, 0,4-0,7 is common and they often have higher Fs as well (compared to the same driver size) to give you good output 70-120Hz. This also results in a higher -f3, which is a pretty meaningless number if you got power imo. Just EQ the FR.

Venting the back wave into the cabin results in a acoustic disaster. It should be sealed or vented to the outside. It's impossible to use the inside of the door as some kind of ported design and expect good results.

The SPL created by the driver is Xmax * Sd. You need power and displacement, that's all. EQ the response to give you the desired amount of midbass again, try increasing 80-120Hz. Dampening the door panels improves the sound in almost every case, the more the better ^^

Sent from my Samsung Galaxy 3 via Tapatalk.
 

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i have modeled many drivers using the door as a volume sealed enclosure.
Unless you have an advanced modelling program it cannot be done properly. Losses and the transfer function of the car needs to be considered. Losses, which are quite immense in a door changes the impedance response of the driver... in WinISD you can simulate this somewhat by lowering Qp from 10.00 to 1,5-3 depending on install. Transfer function of the car can be simulated somewhat half-assed with a "Linkwitz transform" with the filter values 20/80Hz (extension/start value) and with a Q of 0,707. Not close to accurate but it's better than nothing.

When choosing a midbass driver I usually go with a high Xmax, mid Q, mid Fs. Needs to have good non-linear distortion performance in the 60-200Hz area as well.

Sent from my Samsung Galaxy 3 via Tapatalk.
 

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Stock speakers usually have very high Q (like 0,7-1,0) which gives you a bump in FR around Fs of the driver. This gives you bass. The resonance of the door panel is distortion, distortion adds to the fundamental and gives the illusion of... again; more bass. Aftermarket mids are NOT designed to act like subs, they have usually lower Qt than stock drivers, 0,4-0,7 is common and they often have higher Fs as well (compared to the same driver size) to give you good output 70-120Hz. This also results in a higher -f3, which is a pretty meaningless number if you got power imo. Just EQ the FR.

Venting the back wave into the cabin results in a acoustic disaster. It should be sealed or vented to the outside. It's impossible to use the inside of the door as some kind of ported design and expect good results.

The SPL created by the driver is Xmax * Sd. You need power and displacement, that's all. EQ the response to give you the desired amount of midbass again, try increasing 80-120Hz. Dampening the door panels improves the sound in almost every case, the more the better ^^

Sent from my Samsung Galaxy 3 via Tapatalk.
I am not taliking about dampening- I am talking about venting. You can get bass in an OEM door without dampening and without resonance. Bass is not always door panel or structural resonance.
The main point is that drivers meant for IB CAN LOSE BASS OUTPUT IF THEY ARE SEALED which happens in lots of instances where people go crazy with their dampening / deadening / hole sealing process. I have had this happen and have corrected it.

I also disagree that venting the backwave in a controllable faashion with a calculated vent size is not an acoustic disaster. I have seen this done successfully many times.

The idea is to experiment to see what sounds best- if you are over sealed and lost bass. Try venting to the dampened space in the door card or the interior.

The idea that F3 is meaningless and you should just EQ to compensate is absolutely ridiculous. I have tried several drivers with varying F3 approximation and in each instance the calcuation was confirmed in the install. For example the recent forum boner silver flute drivers calculated to an F3 of 175Hz in my 2 cuft doors. They sounded weak and lacking bass and no amount of EQ could make them acceptable.
My current HAT drivers calculate to an F3 of 95 Hz and the difference in bass is astounding.

I agree about the dampening, just not the sealing.
 

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Unless you have an advanced modelling program it cannot be done properly. Losses and the transfer function of the car needs to be considered. Losses, which are quite immense in a door changes the impedance response of the driver... in WinISD you can simulate this somewhat by lowering Qp from 10.00 to 1,5-3 depending on install. Transfer function of the car can be simulated somewhat half-assed with a "Linkwitz transform" with the filter values 20/80Hz (extension/start value) and with a Q of 0,707. Not close to accurate but it's better than nothing.

When choosing a midbass driver I usually go with a high Xmax, mid Q, mid Fs. Needs to have good non-linear distortion performance in the 60-200Hz area as well.

Sent from my Samsung Galaxy 3 via Tapatalk.
I am not looking for absolute modeling. I am looking for relative comparison between drivers to help me decide without hearing. This is irrespective of transfer function.
Deriving a driver's F3 in an assumed enclosed door volume has been a rock solid means of determining bass output- the lower the better- see examples above and I have done more as well.
 

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This happens when we put a lot of deadening material on the doors, it is hard to get used to the difference and hear less bass with some music but not all types of music, some may actually sound better than if the doors were not deaden.

Doors only get heavy, wives or Gf complain they can't close them etc.

I guess the best solution is to have a sub that can blend after having the xover settings set right for the front drivers.

It is Great to know about the venting option and experiment with that, it may be worth take time and some may try that option. In my experience a bit of EQ helped me get more bass, every door may be different and YMMV.

OP, try to post your approach to fix this issue and once you achieve better results, let us know how you improved the sound to your satisfaction.
 

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I disagree (again) about venting anything to the front of the driver. It will result in less bass, not more. Maybe I'm not getting what you mean? The first rule of any form of speaker box building is to isolate the backwave from the front wave. Do you vent an ordinary sealed subwoofer enclosure for more bass as well? It can actually be done (not more bass but venting in general) using an aperiodic (resistive) vent, but that's another story.

SPL output IS displacement. We need to move air, simple as that. Which driver we use determines how efficient the design will be. It's reduntant to use drivers obviously not suited for IB with -f3 at 150Hz or whatever. I've tried countless mids in door installations, PA - home audio - car audio specific drivers... unless the driver simply suck for the application I always manage to create lots of midbass with properly damped and sealed doors with x amount of EQ. You can lose a heavy amount of output if there's any form of leakage going on, just a 0,5" screw hole not sealed means lower output. I've measured this effect more than once so I have plenty experience.

Stock speakers might have bass output BUT it's generally lots of distortion and tons of resonances (doesn't necessarily mean that you feel the vibrations), reduce both and I promise you, we will perceive less bass. The old 80's speakers "Mission" used crappy unbraced enclosures to reinforce the bass. Imo, that's not the way to do it. I rather have clean less midbass than more midbass created by resonances and distortion.

IMO. We should NOT vent the backwave in IB or "Sealed" to front of the driver. It's a generally accepted rule that an acoustic shortcut (destructive interference) occurs whenever a 180 degree out-of-phase wave hits the front wave which is exactly what leakage mean.

Sent from my Samsung Galaxy 3 via Tapatalk.
 

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I disagree (again) about venting anything to the front of the driver. It will result in less bass, not more. Maybe I'm not getting what you mean? The first rule of any form of speaker box building is to isolate the backwave from the front wave. Do you vent an ordinary sealed subwoofer enclosure for more bass as well? It can actually be done (not more bass but venting in general) using an aperiodic (resistive) vent, but that's another story.

SPL output IS displacement. We need to move air, simple as that. Which driver we use determines how efficient the design will be. It's reduntant to use drivers obviously not suited for IB with -f3 at 150Hz or whatever. I've tried countless mids in door installations, PA - home audio - car audio specific drivers... unless the driver simply suck for the application I always manage to create lots of midbass with properly damped and sealed doors with x amount of EQ. You can lose a heavy amount of output if there's any form of leakage going on, just a 0,5" screw hole not sealed means lower output. I've measured this effect more than once so I have plenty experience.

Stock speakers might have bass output BUT it's generally lots of distortion and tons of resonances (doesn't necessarily mean that you feel the vibrations), reduce both and I promise you, we will perceive less bass. The old 80's speakers "Mission" used crappy unbraced enclosures to reinforce the bass. Imo, that's not the way to do it. I rather have clean less midbass than more midbass created by resonances and distortion.

IMO. We should NOT vent the backwave in IB or "Sealed" to front of the driver. It's a generally accepted rule that an acoustic shortcut (destructive interference) occurs whenever a 180 degree out-of-phase wave hits the front wave which is exactly what leakage mean.

Sent from my Samsung Galaxy 3 via Tapatalk.
I get what you are saying. Venting the back wave into the interior should only be done if the modeling suggests the F3 will be lower, with a correctly sized vent- and if the modeling suggests that the driver is suitable for ported enclosure.
Many people have built ported enclosures for their midbass drivers.
In other words it depends on the driver's T/S parameters and the door's volume.
 

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Yes ofc you can make a ported enclosure for a midbass driver and this, per definition require a vent. BUT, I argue against using the interior door volume as an enclosure for a vented alignment. If going ported, the vent needs to be calculated and tuned properly. An arbitrary sized hole somewhere won't do. Also for a vented alignment to work, the interior pressure will be higher compared to a sealed enclosure of the same size. Furthermore, ported enclosures unload below its tuning frequency (Fb), unloading is a serious issue here, the bigger this vent (vs length) gets, the higher up in frequency (Fb) occurs. This makes it even more important to use a dedicated, calculated and proper enclosure for the driver.

If you have measurements, please post them (before/after). Interesting to see what happened once you vented the door. SPL vs Freq and Distortion plots, would be nice.

Sent from my Samsung Galaxy 3 via Tapatalk.
 
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