sub mounting
Originally Posted by bmanson
If it was as simple as just swapping the polarity of the sub I would have done it, but the sound really did not complement the Q series quarts in the door, so I went an alternative route which in the end I feel sounds and looks better.
so really, the problem was the sub setup and not the polarity
Joined: May 2001
Posts: 8,702
Likes: 5
From: California
Bighenet
A key challenge with free air designs in a GS is cancellation.
The key problem with this set up is wave cancellation due to the rear sound wave mixing with the front wave of the woofer.
This is one key reason why many percieve boxes as superior is because in order to go free air in a trunk, you essentially need to isolate your trunk as if it were the enclosure. Why? Because it is the enclosure.
You are essentially getting cancellation by the rear sound wave being 180 degrees out of phase with the front sound wave. For those who haven't taken beginning Physics or are car audio novices, that means the front wave cancels out the rear wave, causing a loss in bass. This effect is not 100%, but it is enough where it can significantly cause a loss in low frequency bass.
Please excuse the bass101 course, but I think some might benefit from the following:
Try this experiment: Take a home pair of speakers known to play good bass. Place the speakers facing each other about a foot apart and turn up the bass boost and listen to them at a decent volume level.
Now turn off the audio power.
You then need to reverse the polarity on one of the speakers (only one) by switching the wires . Positive is wired to negative and negative wired to positive. Positive is usually the wire marked with a stripe and the positive speaker terminal is red. This experiment absolutely does not hurt your speakers or your amp/receiver. So don't get scared.
Now turn on the system again and play the speakers at the same volume with the bass settings the same.
You should hear more than a 90% loss in low bass volume. That's what I'm calling cancellation and you just demonstrated the power of it's affect on bass performance.
Take one step further and rotate the speakers back to back. You will now hear bass, but only at certain positions in the room, you will still hear cancellation depending on your position.
So where's the cancellation problem on a GS?
A couple of key areas:
First off the rear deck lid is only separating the woofers rear sound wave from the front sound wave by a thin piece of fiber board and sheet metal.
This makes for a very poor isolator. Imagine if you tried to make a home speaker enclosure out of that 1/8 thick fiberboard and sheetmetal. Not only is it a rattle trap, you will not hear very good bass because of the cancellation.
Try playing bass through a woofer without being installed in an enclosure. Do you hear much bass? No, because the rear wave is not isolated.
The second area for improvement is behind the seat. The arm rest is a key location for the rear wave to exit into the cabion and mix with the front wave. You should probably hear a small loss when you play with the arm rest down than when it is up.
For a Free Air Install these are Critical problems that must be resolved to get true quality bass.
A key way for everyone to appreciate this is simple. You have all seen woofers mounted into the trunk or in a box inside the trunk. When these systems play, the bass inside the cabin penetrates even if there is no opening. This concept is good for those boxed set ups, but you want entirely the opposite effect with a free air system.
Most people don't think about this, but the bass energy coming out of the front of a woofer is equal (and opposite in phase) to the energy coming out of the rear of the woofer at any given volume. At high levels, that's a lot of rear energy to keep isolated from the outside world and your ears.
If this rear woofer energy IS NOT isolated from the front energy, the cancellation will be great.
So now we see one key reason why a box sounds better and why they are built out of thick acoustic absorbing materials There are many other reasons why we benefit from a box, but I just want to point out that a free air set up is more difficult to do "RIGHT" in a car environment.
What's the fix?
The answer is not a simple one.
You basically need the rear deck to be an acoustic barrier.
Will Dynamat do this? Hardly. All it does is eliminate vibration and isolate the rear wave a bit. I will go on to say that you won't see anyone building a home or automotive sealed enclosure using Dynamat and a thin piece of wood. The dynamat helps but it is hardly adequate.
One key way to build a solid barrier is to rebuild the rear deck lid out of 1/2 to 3/4 inch MDF. This is a material similar to particleboard but much denser, stronger and twice the weight and cost of particleboard.
This is also the same material used in (I'll guesstimate) 90% of all the high end home speakers and subs on the consumer market.
Any true custom car audio shop worth their salt has done this type of install. Do note that shops have been doing this type of deck lid mod for more than 25 years. Go somewhere else if the shop you consider is ignorant to this concept.
The wood can also be upholstered in any material you like.
I have seen many well designed deck lids that look "Better" than the OEM decklid.
The second area of improvement will be to build a wall behind the seat area to replace that corrogated plastic liner currently in your trunk.
Use the same MDF material for this if possible.
The seat area is isolated much better due to the thick foam of the seat itself. This is a hard core audiofile level modification, so consider this a tweak.
If you choose to just mount the woofer to the existing sheetmetal, you may get a reasonable amount of bass, you just won't know how much better it could sound.
Powering it with high power and spending a ton of money on a mondo magnet woofer will surely help the sound. This compensates for the loss, but is not a fix, and honestly, anyone who spends that kind of money should also invest part of it into building a better deck lid. Get the performance you paid for.
So in the end, my suggestions are not a requirement. I only say that because the volume and quality of the bass you can get is up to how much of an audiophile or a bass head you are and nothing else.
For those who want their trunk space, but also require High volume or High Quality bass, it is achievable if you follow the above suggestions and use a Quality Woofer "Designed" for free air. You can always know if a woofer is designed strictly for free air if they tell you NOT to put the speaker in a box say roughly 2 cu ft in volume or less.
Any company that says their woofer will do free air and also play just as well in a 1 cu. ft. sealed enclosure is blowing smoke.
For those who can give up some trunk space, a custom or pre-made sub enclosure is a lot easier.
A key challenge with free air designs in a GS is cancellation.
The key problem with this set up is wave cancellation due to the rear sound wave mixing with the front wave of the woofer.
This is one key reason why many percieve boxes as superior is because in order to go free air in a trunk, you essentially need to isolate your trunk as if it were the enclosure. Why? Because it is the enclosure.
You are essentially getting cancellation by the rear sound wave being 180 degrees out of phase with the front sound wave. For those who haven't taken beginning Physics or are car audio novices, that means the front wave cancels out the rear wave, causing a loss in bass. This effect is not 100%, but it is enough where it can significantly cause a loss in low frequency bass.
Please excuse the bass101 course, but I think some might benefit from the following:
Try this experiment: Take a home pair of speakers known to play good bass. Place the speakers facing each other about a foot apart and turn up the bass boost and listen to them at a decent volume level.
Now turn off the audio power.
You then need to reverse the polarity on one of the speakers (only one) by switching the wires . Positive is wired to negative and negative wired to positive. Positive is usually the wire marked with a stripe and the positive speaker terminal is red. This experiment absolutely does not hurt your speakers or your amp/receiver. So don't get scared.
Now turn on the system again and play the speakers at the same volume with the bass settings the same.
You should hear more than a 90% loss in low bass volume. That's what I'm calling cancellation and you just demonstrated the power of it's affect on bass performance.
Take one step further and rotate the speakers back to back. You will now hear bass, but only at certain positions in the room, you will still hear cancellation depending on your position.
So where's the cancellation problem on a GS?
A couple of key areas:
First off the rear deck lid is only separating the woofers rear sound wave from the front sound wave by a thin piece of fiber board and sheet metal.
This makes for a very poor isolator. Imagine if you tried to make a home speaker enclosure out of that 1/8 thick fiberboard and sheetmetal. Not only is it a rattle trap, you will not hear very good bass because of the cancellation.
Try playing bass through a woofer without being installed in an enclosure. Do you hear much bass? No, because the rear wave is not isolated.
The second area for improvement is behind the seat. The arm rest is a key location for the rear wave to exit into the cabion and mix with the front wave. You should probably hear a small loss when you play with the arm rest down than when it is up.
For a Free Air Install these are Critical problems that must be resolved to get true quality bass.
A key way for everyone to appreciate this is simple. You have all seen woofers mounted into the trunk or in a box inside the trunk. When these systems play, the bass inside the cabin penetrates even if there is no opening. This concept is good for those boxed set ups, but you want entirely the opposite effect with a free air system.
Most people don't think about this, but the bass energy coming out of the front of a woofer is equal (and opposite in phase) to the energy coming out of the rear of the woofer at any given volume. At high levels, that's a lot of rear energy to keep isolated from the outside world and your ears.
If this rear woofer energy IS NOT isolated from the front energy, the cancellation will be great.
So now we see one key reason why a box sounds better and why they are built out of thick acoustic absorbing materials There are many other reasons why we benefit from a box, but I just want to point out that a free air set up is more difficult to do "RIGHT" in a car environment.
What's the fix?
The answer is not a simple one.
You basically need the rear deck to be an acoustic barrier.
Will Dynamat do this? Hardly. All it does is eliminate vibration and isolate the rear wave a bit. I will go on to say that you won't see anyone building a home or automotive sealed enclosure using Dynamat and a thin piece of wood. The dynamat helps but it is hardly adequate.
One key way to build a solid barrier is to rebuild the rear deck lid out of 1/2 to 3/4 inch MDF. This is a material similar to particleboard but much denser, stronger and twice the weight and cost of particleboard.
This is also the same material used in (I'll guesstimate) 90% of all the high end home speakers and subs on the consumer market.
Any true custom car audio shop worth their salt has done this type of install. Do note that shops have been doing this type of deck lid mod for more than 25 years. Go somewhere else if the shop you consider is ignorant to this concept.
The wood can also be upholstered in any material you like.
I have seen many well designed deck lids that look "Better" than the OEM decklid.
The second area of improvement will be to build a wall behind the seat area to replace that corrogated plastic liner currently in your trunk.
Use the same MDF material for this if possible.
The seat area is isolated much better due to the thick foam of the seat itself. This is a hard core audiofile level modification, so consider this a tweak.
If you choose to just mount the woofer to the existing sheetmetal, you may get a reasonable amount of bass, you just won't know how much better it could sound.
Powering it with high power and spending a ton of money on a mondo magnet woofer will surely help the sound. This compensates for the loss, but is not a fix, and honestly, anyone who spends that kind of money should also invest part of it into building a better deck lid. Get the performance you paid for.
So in the end, my suggestions are not a requirement. I only say that because the volume and quality of the bass you can get is up to how much of an audiophile or a bass head you are and nothing else.
For those who want their trunk space, but also require High volume or High Quality bass, it is achievable if you follow the above suggestions and use a Quality Woofer "Designed" for free air. You can always know if a woofer is designed strictly for free air if they tell you NOT to put the speaker in a box say roughly 2 cu ft in volume or less.
Any company that says their woofer will do free air and also play just as well in a 1 cu. ft. sealed enclosure is blowing smoke.
For those who can give up some trunk space, a custom or pre-made sub enclosure is a lot easier.
Last edited by RMMGS4; May 10, 2006 at 01:47 AM.
Joined: May 2001
Posts: 8,702
Likes: 5
From: California
Originally Posted by UberNoob
^^^^^
thats the mother of all sub write up
my bow to you!
thats the mother of all sub write up
my bow to you!
Thanks Noob
That's just years of thread posts all rolled up into one.
I can see where this thread conversation is headed, so I thought I'd throw out most of the pertinent information.
Driver School Candidate
Joined: Dec 2005
Posts: 40
Likes: 0
From: PA
Originally Posted by RMMGS4
Thanks Noob
That's just years of thread posts all rolled up into one.
I can see where this thread conversation is headed, so I thought I'd throw out most of the pertinent information.
That's just years of thread posts all rolled up into one.
I can see where this thread conversation is headed, so I thought I'd throw out most of the pertinent information.
Driver
Joined: Mar 2001
Posts: 170
Likes: 1
From: New Jersey
From years of IASCA competition and at least $100,000.00 spent on car audio during that process (three competition vehicles constructed since 1991), this is what my installers (Bill Acevedo and Omar Buker) and I determined in my GS:
System: Best SQ (sub wise) for the buck - use the "awkward" space in the trunk for 2 woofers in a sealed enclosure and throw as much power as you can afford to buy at it. In my case, we used two 12 Eclipse aluminum woofers in a sealed enclosure powered by a Zapco 9.0. (Trunk is Dynamatted to the high heavens (as is the rest of the car, in excess of 10 boxes of dynamat)) Rest of system consists of a DLS 3 way - 6 mid bass in the doors powered by a Zapco 4.0 bridged, 4 and tweet in custom kicks powered by another Zapco 4.0. Using a Pioneer P9 and digital processor (digital eq, xover, time alignment etc). No back speakers.
Results: Only took it to one show after only 8 or 9 hours of tuning - took 3rd at 2002 IASCA finals. Manville Smith of JL Audio listened to my car, all of the experts, some of the pros, and one novice at that event as he was doing the "Dinosaur Awards" and, according to him and his wife, I rated higher than everyone other than Gary Biggs, Uncle Larry, and a car built/tuned by Buwalda. No flash, no mega dollar install, no computer tuning, hell, time alignment wasn't even set. just straight up old fashioned tuning and speaker placement.
Future: IF I keep the car (big IF - anyone want to buy it), we are removing the factory back deck (more holes than swiss cheese and way too thin to support a real woofer working its a$$ off), welding in steel plate, dynamatting it, installing two woofers free air and going with a stealth trunk - I will lose overall volume (dbs) but who cares - my subs are crossed at 40 hz and down 24db xover slope. Remember - this is a SQ system that still burps SPL in the 140s. My midbasses do much of the punch that you "hear", the subs just rock the car and flex the roof........... Nothing like having 3000 + watts rms to power your system.
System: Best SQ (sub wise) for the buck - use the "awkward" space in the trunk for 2 woofers in a sealed enclosure and throw as much power as you can afford to buy at it. In my case, we used two 12 Eclipse aluminum woofers in a sealed enclosure powered by a Zapco 9.0. (Trunk is Dynamatted to the high heavens (as is the rest of the car, in excess of 10 boxes of dynamat)) Rest of system consists of a DLS 3 way - 6 mid bass in the doors powered by a Zapco 4.0 bridged, 4 and tweet in custom kicks powered by another Zapco 4.0. Using a Pioneer P9 and digital processor (digital eq, xover, time alignment etc). No back speakers.
Results: Only took it to one show after only 8 or 9 hours of tuning - took 3rd at 2002 IASCA finals. Manville Smith of JL Audio listened to my car, all of the experts, some of the pros, and one novice at that event as he was doing the "Dinosaur Awards" and, according to him and his wife, I rated higher than everyone other than Gary Biggs, Uncle Larry, and a car built/tuned by Buwalda. No flash, no mega dollar install, no computer tuning, hell, time alignment wasn't even set. just straight up old fashioned tuning and speaker placement.
Future: IF I keep the car (big IF - anyone want to buy it), we are removing the factory back deck (more holes than swiss cheese and way too thin to support a real woofer working its a$$ off), welding in steel plate, dynamatting it, installing two woofers free air and going with a stealth trunk - I will lose overall volume (dbs) but who cares - my subs are crossed at 40 hz and down 24db xover slope. Remember - this is a SQ system that still burps SPL in the 140s. My midbasses do much of the punch that you "hear", the subs just rock the car and flex the roof........... Nothing like having 3000 + watts rms to power your system.
Originally Posted by Ira Senoff
Future: IF I keep the car (big IF - anyone want to buy it), we are removing the factory back deck (more holes than swiss cheese and way too thin to support a real woofer working its a$$ off), welding in steel plate, dynamatting it, installing two woofers free air and going with a stealth trunk - I will lose overall volume (dbs) but who cares - my subs are crossed at 40 hz and down 24db xover slope.
.I'm using the stock deck only because I dont want to tear it apart yet
. Not to mention, there are no more IASCA events around here to I have no motivation to work on my system. 
Driver
Joined: Mar 2001
Posts: 170
Likes: 1
From: New Jersey
I have a 2000 GS 400 Platinum Series. After 70000 miles, I have not had a problem with batteries or alternators (yet) for a couple of reasons: It is a SQ car - gains are not cranked up and I listen to the music - I usually don't play it at volumes with the intent of rattling windows in neighboring counties. Also, I don't run the system for long periods of time with the engine off (unless I am on a charger).
Wasn't aware that Winslow used MDF first - we knew right up front that steel would be easier to work with and give a far better result - never even considered using MDF in that application.
For the record, not too many IASCA events here either - one of the reasons why I really no longer compete (the others being family and a busy law practice to run). Also, since no competitions, reason why I would like to sell the car with the system. But I still love my mobile tunes - heavily conflicted on the issue of whether or not the next car will get a system.
Wasn't aware that Winslow used MDF first - we knew right up front that steel would be easier to work with and give a far better result - never even considered using MDF in that application.
For the record, not too many IASCA events here either - one of the reasons why I really no longer compete (the others being family and a busy law practice to run). Also, since no competitions, reason why I would like to sell the car with the system. But I still love my mobile tunes - heavily conflicted on the issue of whether or not the next car will get a system.
Pole Position
Joined: Jun 2006
Posts: 309
Likes: 0
From: usa
bighenet -
do you have pix of your setup? i am curious to see what you did and how you did it....
RMMGS4 -
how did you mount the wood piece? is the rear deck on top, then the sub, then the wood piece?
forgive my ignorance...i am a newbie....would like to see more pix of your wood mounting kit if possible...
thanks!
do you have pix of your setup? i am curious to see what you did and how you did it....
RMMGS4 -
how did you mount the wood piece? is the rear deck on top, then the sub, then the wood piece?
forgive my ignorance...i am a newbie....would like to see more pix of your wood mounting kit if possible...
thanks!