Improving OE Door Speaker Clarity and Depth

[tadda]

This is Part 2 in a series of on how to improve the Supra's OE audio system sound clarity, midbass response, and eliminate vibrational noise and distortions...

Part 1 on How to Improve OE Subwoofer Quality and Eliminate Vibrations discussed identifying problem areas and making improvements to the OE Harmon Kardon 8" Subwoofer system in the Supra. Once these basic design issues were corrected the subwoofer's bass response actually sounds surprisingly good now..

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Now with respect to this project, I also found that the Harmon Kardon door speakers are pretty decent speakers as well...And as with the Subwoofer application, there were clear areas for improvement identified, specifically with regards to the midrange door speakers and that once these areas were addressed, midrange clarity, mid-bass response, and overall sound depth were noticeably improved...

There were 3 primary areas of focus:

• Vibrational noise suppression in panels
• Midrange Isolation
• Reduction in mid-bass damping effects

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First is removal of door panel...Outlined below are the steps for door panel removal which is fairly straight forward process and not difficult to do...

In this video below they show how to remove the door panel....



Shown below is the door with panel removed...

Close up of midrange speaker grill and directional tube...

Harmon Kardon Midrange Speaker...

Midrange speaker removed showing rear cavity...

1" speaker wadding was added to suppress destructive back reflections, reduce vibrational noise, and improve spatial clarity and midbass response...I also added dynamat around the outer speaker housing wall for added isolation and vibrational noise reduction.....

Pictured below is the outer door panel..

Areas were identified to apply sound deadening / vibration reducing material...I used the marked taped areas as templates to cut from sound deadening material...

Here I applied Dynamat Extreme to areas shown below...

I then applied 1/4" adhesive backed Noico foam to the inner wall and dynamat sound deadening material to the outer wall of the midrange directional tube...This was done to improve directional sound quality and clarity while also insulating and reducing any vibrational noise that may have been created by the thin plastic midrange directional tube itself...

Getting rid of vibrations is like playing wack-a-mole...After doing the doors which helped improve midrange response quite a bit, the tweeter resonant vibrations then became more obvious! After some investigation, I found out that it was caused by the housing holding the tweeter in place...I then took off the door panels once again and wedged some thin 1/4" round felt pads (where you find at Lowes or Home Depot) and also added dynamat surrounding the tweeter housing as shown in pic below...This got rid the tweeters vibrational resonance I was experiencing ...

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Summary and Final Thoughts:

Overall I'm very pleased with the results...I've noticed that the upper midrange is much clearer, more focused, and less distorted while the midbass response now has more depth and richness which has noticeably improved overall sound quality...

As I mention in my other thread How to Improve OE Subwoofer Quality and Eliminate Vibrations (which still holds true for this application as well) is that for anyone considering installing direct replacement speakers in an attempt to improve sound quality, these basic improvements should be done first before replacing speakers or you'll going to be left with the same issues regarding vibrational noise and sound distortions...

All the basic components are there in the current OE sound system to produce a fairly high quality sounding system...What I discovered after implementing all these improvements is that surprisingly, the OE Harmon Kardon speakers in the Supra are actually very good speakers once you correct some basic design issues that for some reason were overlooked by Toyota...

These are currently my new EQ settings (below) after improvements were made to current OE sound system...I can now raise the volume close to 3/4 of max with minimal distortions or vibrational noise and the overall sound quality has significantly improved where the sound is much clearer and has far more range and depth to it...Bass response is deeper, less distorted, and tighter...

How to Setup and Optimize Sound Quality using OE Equalizer

Understand that before all these improvements were made I couldn't even play music past 1/3 volume and also had to significantly reduce bass and midrange equalization levels close to zero to avoid having terrible vibrational noise and sound distortions from occurring...

After correcting these problems the next obvious step is to upgrade the amplifier which is now the limiting factor...This will provide more headroom which in turn should further improve clarity and response and reduce overall distortions that occur when the current OE HK amp is pushed past 3/4 volume (which is very loud btw!)...In other words, a higher power DSP amp upgrade wouldn't need to be pushed as hard to achieve the same volume with far less distortion...

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[Supbrah]

Excellent write up sir. Thank you so much.

A little worried about the wadding added in the door...seems like there is some potential for it to get wet. I see what look like water spots on the window guide in the door.

I'm also kinda bummed that it looks like the armrests don't come off the door panels (side project of mine to give the interior a little color).

 

[tadda]

Excellent write up sir. Thank you so much.

A little worried about the wadding added in the door...seems like there is some potential for it to get wet. I see what look like water spots on the window guide in the door.

I'm also kinda bummed that it looks like the armrests don't come off the door panels (side project of mine to give the interior a little color).

Thanks! it looked as if the armrest actually pulls off but I'm not 100% on that...

I investigated that before applying wadding...Those spots are not from outside washing or rain water ingress...I'm pretty confident that this occurred during the tint install process where soapy water is applied to the interior side of window and those installers can get pretty sloppy with the soapy water!....Any water that runs down the outer side of the window will actually drip far away from that area so I'm not at all concerned....

Here is a better pic....That space is fairly shallow and the window guide is centered within the door space and the window actually slides down behind it....Also, notice how clean the main horizontal re-enforcement beam is which runs along the outer door panel...Other than those soap spots on the guide there was no evidence of outside water ingress anywhere near the speaker area....

Pic of door with window detail with speaker location...

 

[Supbrah]

Thanks! it looked as if the armrest actually pulls off but I'm not 100% on that...

I investigated that before applying wadding...Those spots are not from outside washing or rain water ingress...I'm pretty confident that this occurred during the tint install process where soapy water is applied to the interior side of window and those installers can get pretty sloppy with the soapy water!....Any water that runs down the outer side of the window will actually drip far away from that area so I'm not at all concerned....

Here is a better pic....That space is fairly shallow and the window guide is centered within the door space and the window actually slides down behind it....Also, notice how clean the main horizontal re-enforcement beam is which runs along the outer door panel...Other than those soap spots on the guide there was no evidence of outside water ingress anywhere near the speaker area....

Pic of door with window detail with speaker location...

I should have known better than to question you.

 

[tadda]

I should have known better than to question you.

It was a very good observation on your part though!

I'm my biggest critic...As an Engineer I tend over-analyze and question everything I do...Most of the time I get it right...but sometimes I don't and chalk it up as a learning experience...

 

[Half Vast]

Nicely done @tadda ! Very easy to follow instructions. Now that you've completed this stage, what are your thoughts on the overall system?

 

[tadda]

Nicely done @tadda ! Very easy to follow instructions. Now that you've completed this stage, what are your thoughts on the overall system?

I mention this in my last thread and this still hold true...All the basic components are there in the system to produce a decent quality sound system...What I discovered after implementing all these improvements is that surprisingly, the OE Harmon Kardon speakers in the Supra are actually very good speakers once you correct some very basic design issues that for some reason were overlooked by Toyota...

For anyone considering installing direct replacement speakers as an attempt to improve sound quality, these basic improvements should be done first before replacing speakers or you'll going to be left with the same issues regarding vibrational noise and sound distortions...

These are my new EQ settings (below) after improvements made to current OE sound system...I can now raise the volume close to 3/4 of max with minimal distortions or vibrational noise and the overall sound quality has significantly improved where the sound is much clearer and has far more range and depth to it...Bass response is deeper, less distorted, and tighter...

Understand that before all these improvements were made I couldn't even play music past 1/3 volume and still had to significantly reduce bass and midrange equalization levels close to zero to avoid having terrible vibrational noise and sound distortions from occurring...

After correcting these problems the next obvious step is to upgrade the amplifier which is now the limiting factor...This will provide more headroom which in turn should further improve clarity and response and reduce overall distortions that occur when the current OE HK amp is pushed past 3/4 volume (which is very loud btw!)...In other words, a higher power DSP amp upgrade wouldn't need to be pushed as hard to achieve the same volume with far less distortion...

 

[tadda]

@tada,
can you use a speaker baffel instead of the wadding? https://www.parts-express.com/xtc-4-round-foam-baffle-pair--260-782

I saw / considered those...A big concern of mine with these types of closed cell foam baffle / enclosure is that the volume of space would not be large enough behind the speaker and could actually diminish bass response...To explain further, you would also have to trim the baffle down quite a bit due to depth restrictions caused by the wide vertical window rail which would greatly limit the baffle enclosure volume...I've also seen reviews where the backs of these were actually blown out or torn open due to too much back pressure as these are not breathable compared to speaker wadding...

I am considering another option and that is applying 2 sections an Anechoic Pad (one pad cut in half) and then apply to the surfaces of the window rail and the inside of outer door panel directly behind the speaker which would serve a similar purpose as the wadding of eliminating bass destructive back reflections...I already have these pads in hand and will be exploring further within the next few days...

 

[tadda]

Update: (added to first post)

Getting rid of vibration noise and distortions is like playing wack-a-mole...After doing the doors, which helped improve midrange response quite a bit, the tweeter resonant vibrations then became more obvious and was something I had overlooked...After some investigation, I found out that it was caused by the housing holding the tweeter in place...I then took off the door panels once again and wedged some thin 1/4" round felt pads (where you find at Lowes or Home Depot) and also added dynamat surrounding the tweeter housing as shown in pic below...This got rid the tweeters' vibrational resonance I was experiencing ...

 

[METAL]

I have left over Noico Red 315 from the OE Sub Project Thread. Can I use this in leu of the dynamite around the speaker housing, door panel tube, and door panel?

 

[jorligan]

For those who are going to do a driver swap, it looks like the factory does not crossover the tweeter. You will need to put in an appropriate cap to protect the tweeter. Please correct me if I am wrong. I will be replacing my drivers with the Focal K2 setup but it looks like I will be using the Focal passive crossover unless I elect to go with an active system in the future.

 

[tadda]

For those who are going to do a driver swap, it looks like the factory does not crossover the tweeter. You will need to put in an appropriate cap to protect the tweeter. Please correct me if I am wrong. I will be replacing my drivers with the Focal K2 setup but it looks like I will be using the Focal passive crossover unless I elect to go with an active system in the future.

 

[jorligan]

Thanks for pointing it out. On the videos, it wasn't evident

 

[METAL]

Got around to doing this. I think it made an improvement. Been enjoying the stock system little more recently. I had left over Noico that I applied over the dynamat as well for a little more insulation.

 

[jorligan]

Did the same sound treatment. Replaced the speakers with Focal ES100k. Huge improvement. Now will need to replace or inactivate the center speaker. Need to do the rear speaker upgrade, waiting for the roll bar so I just disassemble the back once.

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