In the VW Passat, there are three door "membranes" that can be treated
with damping sheets (such as Dynamat):

1) The outer sheetmetal door skin
2) The inner sheetmetal plate (removable in all late model Passats)
3) The inside plastic door panel (obviously removable)

The goal is to tighen up the midbass and eliminate "blurring" of the
sound in the lower midrange. So, is it necessary to dampen all three
of these membranes? Which of the three are more important?

If its important to treat the outer sheetmetal door skin (#3 above),
is it a bitch to remove the inner sheetmetal plate (#2 above) to get
to it? Someone said I can just unscrew it and have a friend hold it
close while I access the inside of the outer sheetmetal door skin.
They said something about "cables" inside that have some play in them.
Does anyone know about this, and if its doable?

Any advice would be greatly appreciated !!

Thank you.

In the VW Passat, there are three door "membranes" that can be treated
with damping sheets (such as Dynamat):

1) The outer sheetmetal door skin
2) The inner sheetmetal plate (removable in all late model Passats)
3) The inside plastic door panel (obviously removable)

The goal is to tighen up the midbass and eliminate "blurring" of the
sound in the lower midrange. So, is it necessary to dampen all three
of these membranes? Which of the three are more important?

No, it's not necessary. Sometimes it's not even beneficial, unless there
are vibrations that you can pinpoint. Remove the entire door panel. Look
for any holes that are preventing a seal between the front and back of the
woofer. Seal them with dynamat or equivalent. If they're small, caulk
them.

Okay, thanks. btw, in the original post, I stated " #3 " but I really
meant " #1 ". But I guess you knew what I meant. Thanks again.


No, it's not necessary. Sometimes it's not even beneficial, unless there
are vibrations that you can pinpoint. Remove the entire door panel. Look
for any holes that are preventing a seal between the front and back of the
woofer. Seal them with dynamat or equivalent. If they're small, caulk
them.

Yeah, it's pretty common advice. It's good that you're willing to put in
this sort of effort for front speakers, because IMO that part of the
installation can be the most difficult and it makes or breaks a system.
Most people put too much time into crossing their cables at right angles or
making their sub box into an airtight vault. I almost always end up using
some dynamat, but it's not usually for deadening. There are, however, some
situations where the inside door is like swiss cheese or screwed up. And
then sometimes you've got rattling window motors to contend with. You'll
figure out what you need as you go along.

--
Mark
remove "remove" and "spam" to reply

"Brian" wrote in message
om...
Okay, thanks. btw, in the original post, I stated " #3 " but I really
meant " #1 ". But I guess you knew what I meant. Thanks again.


No, it's not necessary. Sometimes it's not even beneficial, unless
there
are vibrations that you can pinpoint. Remove the entire door panel.
Look
for any holes that are preventing a seal between the front and back of
the
woofer. Seal them with dynamat or equivalent. If they're small, caulk
them.

Not really sure if I agree with MZ on this. I still have a lot to learn,
though.

I applied mastic sheets (Dynamat generic equivalent) and a viscoelastic
spray to the outter door skin, another layer of the sheets in the sheetmetal
plate, more layers on the plate over the holes in an attempt to "seal" the
door (which is never quite totally sealed, BTW) and then use as much mastic
sheets and/or spray on the door panel itself. I also used clear silicone in
many spots as needed.

As far as it NOT being beneficial, every car I've ever owned has had
vibrating, buzzing, and resonating doors. By using the above process I've
elimated almost 100% of every non-musical sound that my 8-inch midbasses
produce inside the door.

Of course, as MZ said, the benefit will vary greatly depending on how bad
the vibrations are to begin with. I've had EXCELLENT luck with the last two
vehicles I've owned.

To save money, I'd install it yourself & stay clear of brand names and go
for generic versions. The only thing I'm worried about after doing this is
what if my electric windows or some other unseen parts quit working? Will
my car manufacturer still be able to service my doors with all that gunk in
there?

Tony


--



What's more likely? That an all-powerful mysterious god created the
universe and then decided not to give any proof of his existence? Or, that
he simply doesn't exist at all? And that we created him so that we wouldn't
have to feel so small and alone. -Eleanor Arroway, Contact

"Brian" wrote in message
om...
In the VW Passat, there are three door "membranes" that can be treated
with damping sheets (such as Dynamat):

1) The outer sheetmetal door skin
2) The inner sheetmetal plate (removable in all late model Passats)
3) The inside plastic door panel (obviously removable)

The goal is to tighen up the midbass and eliminate "blurring" of the
sound in the lower midrange. So, is it necessary to dampen all three
of these membranes? Which of the three are more important?

If its important to treat the outer sheetmetal door skin (#3 above),
is it a bitch to remove the inner sheetmetal plate (#2 above) to get
to it? Someone said I can just unscrew it and have a friend hold it
close while I access the inside of the outer sheetmetal door skin.
They said something about "cables" inside that have some play in them.
Does anyone know about this, and if its doable?

Any advice would be greatly appreciated !!

Thank you.

Oh...and not to say what Mark advised was not correct...I was simply adding
on my opinion.

Tony


--



What's more likely? That an all-powerful mysterious god created the
universe and then decided not to give any proof of his existence? Or, that
he simply doesn't exist at all? And that we created him so that we wouldn't
have to feel so small and alone. -Eleanor Arroway, Contact

"Brian" wrote in message
om...
In the VW Passat, there are three door "membranes" that can be treated
with damping sheets (such as Dynamat):

1) The outer sheetmetal door skin
2) The inner sheetmetal plate (removable in all late model Passats)
3) The inside plastic door panel (obviously removable)

The goal is to tighen up the midbass and eliminate "blurring" of the
sound in the lower midrange. So, is it necessary to dampen all three
of these membranes? Which of the three are more important?

If its important to treat the outer sheetmetal door skin (#3 above),
is it a bitch to remove the inner sheetmetal plate (#2 above) to get
to it? Someone said I can just unscrew it and have a friend hold it
close while I access the inside of the outer sheetmetal door skin.
They said something about "cables" inside that have some play in them.
Does anyone know about this, and if its doable?

Any advice would be greatly appreciated !!

Thank you.

We're apparently in agreement, actually. I said it's important to seal much
of the door (dynamat can be handy), and eliminate rattles. You usually
don't have to dynamat the entire door to achieve this. But in some cars...

--
Mark
remove "remove" and "spam" to reply

"Tony Fernandes" wrote in message
...
Not really sure if I agree with MZ on this. I still have a lot to learn,
though.

I applied mastic sheets (Dynamat generic equivalent) and a viscoelastic
spray to the outter door skin, another layer of the sheets in the
sheetmetal
plate, more layers on the plate over the holes in an attempt to "seal" the
door (which is never quite totally sealed, BTW) and then use as much
mastic
sheets and/or spray on the door panel itself. I also used clear silicone
in
many spots as needed.

As far as it NOT being beneficial, every car I've ever owned has had
vibrating, buzzing, and resonating doors. By using the above process I've
elimated almost 100% of every non-musical sound that my 8-inch midbasses
produce inside the door.

Of course, as MZ said, the benefit will vary greatly depending on how bad
the vibrations are to begin with. I've had EXCELLENT luck with the last
two
vehicles I've owned.

To save money, I'd install it yourself & stay clear of brand names and go
for generic versions. The only thing I'm worried about after doing this
is
what if my electric windows or some other unseen parts quit working? Will
my car manufacturer still be able to service my doors with all that gunk
in
there?

Tony


--



What's more likely? That an all-powerful mysterious god created the
universe and then decided not to give any proof of his existence? Or,
that
he simply doesn't exist at all? And that we created him so that we
wouldn't
have to feel so small and alone. -Eleanor Arroway, Contact

"Brian" wrote in message
om...
In the VW Passat, there are three door "membranes" that can be treated
with damping sheets (such as Dynamat):

1) The outer sheetmetal door skin
2) The inner sheetmetal plate (removable in all late model Passats)
3) The inside plastic door panel (obviously removable)

The goal is to tighen up the midbass and eliminate "blurring" of the
sound in the lower midrange. So, is it necessary to dampen all three
of these membranes? Which of the three are more important?

If its important to treat the outer sheetmetal door skin (#3 above),
is it a bitch to remove the inner sheetmetal plate (#2 above) to get
to it? Someone said I can just unscrew it and have a friend hold it
close while I access the inside of the outer sheetmetal door skin.
They said something about "cables" inside that have some play in them.
Does anyone know about this, and if its doable?

Any advice would be greatly appreciated !!

Thank you.

the three panels may need to be dynamated for three different reasons.

1) the outside door skin is sometimes hard to do, but doing it will
make the entire door overall more DEAD... It may also cut out some
outside road noise...

2) the inside metal skin, where the speaker is likely mounted.
this is the most common panel to dynamat, and would be the most
benificial for the sound of the speaker, which I believe is your goal.

3) the plastic door panel... Sometimes a touch of deadening to
stop rattles may be needed here but unless there is a problem
you prolly dont need it here... Wont hurt though... ;-)

Eddie Runner
http://www.installer.com/tech/

Brian wrote:

In the VW Passat, there are three door "membranes" that can be treated
with damping sheets (such as Dynamat):

1) The outer sheetmetal door skin
2) The inner sheetmetal plate (removable in all late model Passats)
3) The inside plastic door panel (obviously removable)

The goal is to tighen up the midbass and eliminate "blurring" of the
sound in the lower midrange. So, is it necessary to dampen all three
of these membranes? Which of the three are more important?

If its important to treat the outer sheetmetal door skin (#3 above),
is it a bitch to remove the inner sheetmetal plate (#2 above) to get
to it? Someone said I can just unscrew it and have a friend hold it
close while I access the inside of the outer sheetmetal door skin.
They said something about "cables" inside that have some play in them.
Does anyone know about this, and if its doable?

Any advice would be greatly appreciated !!

Thank you.

Thanks Mark and Tony for your advice!

First, I completely accept Mark's direction to seal the inner door
plate holes, first and foremost. As far as I can tell, all these
openings have aleady been sealed, so there is currently a virtually
air-tight barrier between the inside of the door cavity and the inside
of the vehicle.

However, I'm still concerned about a few other mechanisms/dynamics
that may be degrading SQ.

There are two basic Types of problems, as far as I can tell:
A. Those that interfere with the cone driver movement.
B. Those caused by vibrating panels that act as an additional source
of sound.


Type A:

A.1 AIR-PRESSURE FEEDBACK: The effect of vibrating enclosure walls,
as far as a source of air pressure wave "feedback" on the cone action.
In other words, I can imagine the vibrating sheetmetal inner and
outer walls would interfere with cone movement (via air-pressure
waves), and would muddy the sound. I assume this is why speaker
enclosures are built with very rigid walls.

A.2 "BOUNCING" RESONANCE: If we imagine that the enclosure walls are
completely rigid, then the effect of what I called "air-pressure
feedback" above would be eliminated. But the sound waves would still
"bounce around" inside the cavity and could still possibly interfere
with the cone movement. I assume that filling a box with polyfill is
meant to address this, as well as building speaker enclosures to
certain proportions.

Type B:

B.1 Vibrating inner panels will act as an additional "speaker",
similar to a planar speaker (i.e. Magnapan). I imagine that any sound
coming from vibrating interior panels would sound muddy and degrade
the SQ.


Conclusion:

Certain treatments will address each of these Types of problem more
than others. For instance, Dynamat does not address Type A.2
"Bouncing Resonance". Unfortunately, we can not fill our doors will
polyfill. I do plan on lining my door cavity with Bubble-Wrap. (the
*big* bubble variety) This will prevent the sound from bouncing.
(try yelling into a sheet held 2 inches from your mouth, and then try
it with a hard surface instead. You will be amazed.) And it's
waterproof.



As far as stopping the sheetmetal walls from vibrating (Types A.1 and
B.1), the only practicle way to do this would be to stiffen them with
fiberglass. Perhaps by laying a 1/4" layer, and then running ridges
of FB as stiffener beams.

I think that if only Dynamat were used, the panels would still
vibrate. But it lowers the resonant frequency of the sheetmetal, and
it disapates/absorbs a lot of the energy. It's probably a lot easier
than fiberglassing, I would think. So perhaps this is the most
practicle way to go.

But I guess the ultimate would be to Dynamat, then Fiberglass, then
the bubble-wrap.

In closing, I'm not certain how much Type A.1 contributes to bad sound
compared to Types A.2 and B.1. What are your opinions on this? If
Type A.1 is negligible, then there would be no need to treat the outer
door skin with Dynamat or Fiberglass. Not only would this save a lot
of time/effort, but if the door gets "dinged" I don't think the "Dent
Wizard" would be able to pop out the dent if all those layers are
there. Of course, it would be more difficult to dent the door in the
first place, but if it were to dent, it may be more difficult to
repair.

Any thoughts?

Thanks, Eddie.

Please comment on my latest post (in this thread) "Types A.1, A.2
and B.1" problems.

Thank you.

-Brian



Eddie Runner wrote in message ...
the three panels may need to be dynamated for three different reasons.

1) the outside door skin is sometimes hard to do, but doing it will
make the entire door overall more DEAD... It may also cut out some
outside road noise...

2) the inside metal skin, where the speaker is likely mounted.
this is the most common panel to dynamat, and would be the most
benificial for the sound of the speaker, which I believe is your goal.

3) the plastic door panel... Sometimes a touch of deadening to
stop rattles may be needed here but unless there is a problem
you prolly dont need it here... Wont hurt though... ;-)

Eddie Runner
http://www.installer.com/tech/

i dont think I would worry about all that goobldygook...

if your worried about the back waves reflections use the
XTC foam speaker cups, they work great... I really dont think
the back waves in the door are of much consequince.. There
will be reflections, but the large glass panels all around the
listeing area of the car (we call em windows) make FAR MORE
detrimental reflections in the listening area then the back waves
in the doors... (IMO)

Dynamating the door panel where the speaker mounts will
take out virtually all the *RING* from the metal panel, thats
all the vibration you really have to worry about...

if your alittle more serious and if you have room back there
you can build a wood baffle board to mount your speakers on
but if you have seperate subs somewhere else in the car
then trying to tweek for best bass outa the door speakers
is kind of a waste...

Bubble wrap in the doors???
I dont think I would do that...
( I gotta piece right here)
Just touching the stuff or barely moving it makes all kinda
squeekin noises!! I wouldnt want that crap rattling around in
my doors....

Eddie Runner
http://www.installer.com/tech/

Brian wrote:

Thanks Mark and Tony for your advice!

First, I completely accept Mark's direction to seal the inner door
plate holes, first and foremost. As far as I can tell, all these
openings have aleady been sealed, so there is currently a virtually
air-tight barrier between the inside of the door cavity and the inside
of the vehicle.

However, I'm still concerned about a few other mechanisms/dynamics
that may be degrading SQ.

There are two basic Types of problems, as far as I can tell:
A. Those that interfere with the cone driver movement.
B. Those caused by vibrating panels that act as an additional source
of sound.

Type A:

A.1 AIR-PRESSURE FEEDBACK: The effect of vibrating enclosure walls,
as far as a source of air pressure wave "feedback" on the cone action.
In other words, I can imagine the vibrating sheetmetal inner and
outer walls would interfere with cone movement (via air-pressure
waves), and would muddy the sound. I assume this is why speaker
enclosures are built with very rigid walls.

A.2 "BOUNCING" RESONANCE: If we imagine that the enclosure walls are
completely rigid, then the effect of what I called "air-pressure
feedback" above would be eliminated. But the sound waves would still
"bounce around" inside the cavity and could still possibly interfere
with the cone movement. I assume that filling a box with polyfill is
meant to address this, as well as building speaker enclosures to
certain proportions.

Type B:

B.1 Vibrating inner panels will act as an additional "speaker",
similar to a planar speaker (i.e. Magnapan). I imagine that any sound
coming from vibrating interior panels would sound muddy and degrade
the SQ.

Conclusion:

Certain treatments will address each of these Types of problem more
than others. For instance, Dynamat does not address Type A.2
"Bouncing Resonance". Unfortunately, we can not fill our doors will
polyfill. I do plan on lining my door cavity with Bubble-Wrap. (the
*big* bubble variety) This will prevent the sound from bouncing.
(try yelling into a sheet held 2 inches from your mouth, and then try
it with a hard surface instead. You will be amazed.) And it's
waterproof.

As far as stopping the sheetmetal walls from vibrating (Types A.1 and
B.1), the only practicle way to do this would be to stiffen them with
fiberglass. Perhaps by laying a 1/4" layer, and then running ridges
of FB as stiffener beams.

I think that if only Dynamat were used, the panels would still
vibrate. But it lowers the resonant frequency of the sheetmetal, and
it disapates/absorbs a lot of the energy. It's probably a lot easier
than fiberglassing, I would think. So perhaps this is the most
practicle way to go.

But I guess the ultimate would be to Dynamat, then Fiberglass, then
the bubble-wrap.

In closing, I'm not certain how much Type A.1 contributes to bad sound
compared to Types A.2 and B.1. What are your opinions on this? If
Type A.1 is negligible, then there would be no need to treat the outer
door skin with Dynamat or Fiberglass. Not only would this save a lot
of time/effort, but if the door gets "dinged" I don't think the "Dent
Wizard" would be able to pop out the dent if all those layers are
there. Of course, it would be more difficult to dent the door in the
first place, but if it were to dent, it may be more difficult to
repair.

Any thoughts?

Okay, makes sense. At the very least, I'm going to put some
dynamat-type sheet material on the inner metal panel that the speakers
are mounted to. Everyone seems to agree that this would do the most
good. (aside from first sealing any holes)

If I feel up to it when the weather warms up, I may open up the inner
panel to access inside the door cavity to do the outer skin as well.

As far as the bubble wrap goes, I'll reconsider that. But I think if
its glued on there well with contact cement, then it wouldn't make any
noise. I really do think it would help kill any standing waves, and
in general would trap (absorb)any sound waves that would otherwise
bounce (reflect) within the cavity.

A lot depends on whether the door vibration is actually induced by the
sound waves inside the door, or instead from the speaker housing
(metal body) transmitting its vibration directly to the door sheet
metal to which it is attached (like an acoustic guitar string
transmits its vibration to the guitar body). It seems that such
direct transmision would be nipped in the bud by applying the dynamat
material around where the speaker is mounted, as you suggest. But any
vibration caused by the sound waves inside the door cavity would
require dynamat on the rest of the panel(s), and the bubble wrap would
also help, I think. [btw, if you have a guitar, you can actually make
the guitar strings vibrate just by singing a sustained note with your
mouth near the string. especially if you match the note of the
string...]

I'll probably end up dynamating the **** out of everything and be done
with it once and for all. lol.

Again, thank you for your advice!

-Brian




Eddie Runner wrote in message ...
i dont think I would worry about all that goobldygook...

if your worried about the back waves reflections use the
XTC foam speaker cups, they work great... I really dont think
the back waves in the door are of much consequince.. There
will be reflections, but the large glass panels all around the
listeing area of the car (we call em windows) make FAR MORE
detrimental reflections in the listening area then the back waves
in the doors... (IMO)

Dynamating the door panel where the speaker mounts will
take out virtually all the *RING* from the metal panel, thats
all the vibration you really have to worry about...

if your alittle more serious and if you have room back there
you can build a wood baffle board to mount your speakers on
but if you have seperate subs somewhere else in the car
then trying to tweek for best bass outa the door speakers
is kind of a waste...

Bubble wrap in the doors???
I dont think I would do that...
( I gotta piece right here)
Just touching the stuff or barely moving it makes all kinda
squeekin noises!! I wouldnt want that crap rattling around in
my doors....

Eddie Runner
http://www.installer.com/tech/

An additional problem with dynamatting is that you can make the door heavy
as hell. I don't consider that a virtue. I really don't think you'll have
a problem with standing waves due to the geometry of the interior of the
door. Reflecting waves aren't going to be a problem.

--
Mark
remove "remove" and "spam" to reply

"Brian" wrote in message
om...
Okay, makes sense. At the very least, I'm going to put some
dynamat-type sheet material on the inner metal panel that the speakers
are mounted to. Everyone seems to agree that this would do the most
good. (aside from first sealing any holes)

If I feel up to it when the weather warms up, I may open up the inner
panel to access inside the door cavity to do the outer skin as well.

As far as the bubble wrap goes, I'll reconsider that. But I think if
its glued on there well with contact cement, then it wouldn't make any
noise. I really do think it would help kill any standing waves, and
in general would trap (absorb)any sound waves that would otherwise
bounce (reflect) within the cavity.

A lot depends on whether the door vibration is actually induced by the
sound waves inside the door, or instead from the speaker housing
(metal body) transmitting its vibration directly to the door sheet
metal to which it is attached (like an acoustic guitar string
transmits its vibration to the guitar body). It seems that such
direct transmision would be nipped in the bud by applying the dynamat
material around where the speaker is mounted, as you suggest. But any
vibration caused by the sound waves inside the door cavity would
require dynamat on the rest of the panel(s), and the bubble wrap would
also help, I think. [btw, if you have a guitar, you can actually make
the guitar strings vibrate just by singing a sustained note with your
mouth near the string. especially if you match the note of the
string...]

I'll probably end up dynamating the **** out of everything and be done
with it once and for all. lol.

Again, thank you for your advice!

-Brian




Eddie Runner wrote in message
...
i dont think I would worry about all that goobldygook...

if your worried about the back waves reflections use the
XTC foam speaker cups, they work great... I really dont think
the back waves in the door are of much consequince.. There
will be reflections, but the large glass panels all around the
listeing area of the car (we call em windows) make FAR MORE
detrimental reflections in the listening area then the back waves
in the doors... (IMO)

Dynamating the door panel where the speaker mounts will
take out virtually all the *RING* from the metal panel, thats
all the vibration you really have to worry about...

if your alittle more serious and if you have room back there
you can build a wood baffle board to mount your speakers on
but if you have seperate subs somewhere else in the car
then trying to tweek for best bass outa the door speakers
is kind of a waste...

Bubble wrap in the doors???
I dont think I would do that...
( I gotta piece right here)
Just touching the stuff or barely moving it makes all kinda
squeekin noises!! I wouldnt want that crap rattling around in
my doors....

Eddie Runner
http://www.installer.com/tech/

Good point the added weight.

I decided that I'm going to just play it by ear and see how hard it is
to access the inner door cavity. If its too difficult, then I'll just
dynamat the inner sheetmetal to which the speaker is actually mounted.
I'll probably treat the plastic door panel a bit too (the unexposed
side, of course).

It would be an interesting experiment to compare the sound before and
after the treatment. I suspect there is a considerable "placebo"
effect, where your mind convinces you that it *must* sound better.

Perhaps one way to do an A-B comparison would be to play a reference
song and record the sound inside the car with a really high quality
microphone and good DAT recorder. And then after the dynamating,
record the same song using the identical volume and tone settings as
before.

Then, to listen to the before and after recordings on a really good
home reference system or headphones. My feeling is that, if you can't
tell the difference between the recordings (assuming they are very
high quality), then it wasn't worth the effort to dynamat (at least in
that particular instance).

Another more "scientific" approach would be to just play some pink
noise and compare the spectrum results before and after. (keeping in
mind, that would not show the effect on transient response.)

__________


"MZ" wrote in message ...
An additional problem with dynamatting is that you can make the door heavy
as hell. I don't consider that a virtue. I really don't think you'll have
a problem with standing waves due to the geometry of the interior of the
door. Reflecting waves aren't going to be a problem.

--
Mark