Vehicle/Car soundproofing, deadening. Engineers view.

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I am a time served engineer and audio fitter having kitted out many custom installs, starting back in the 1970's,
when an 30 watt stereo was the dogs gonads! Show vehicles raved at having 80 Watts.

How can you get great results with as little cost and effort as possible?
My goal is to provide you with all the information you will need to make your choice and complete your project successfully.

Car audio is a strange subject, and one that people constantly cannot fathom out. Even fitters at your big car accessory shops
have no real idea. All they want is to sell you items that earn them a bigger bonus.

There are 4 main things to consider in car audio.

1. Speakers.
2. Amplification.
3. Source.(head unit).
4. Acoustic treatment.(soundproofing).

It is number 4 that people always ignore, but its the most important. MORE THAN ANY OTHER UPGRADE.

Let me explain.

It's all about noise control.

To block road noise - to be effective, you would need an absorbent material 20 - 60 inches thick.
Right, that's never going to happen in a car.
What we have to do is block the noise using foam (sound deadening material) and bitumen (vibration damping).


Car audio is a crash course in diminishing returns.....

1. Speakers, anything over £100.00 is pretty much wasted money.
Pay more than that and you will get a different sound, but not much improvement.
1a. Subwoofer, you will get the low end response production cars struggle with,
but it will sound detached from the rest of the music.- (not a nice, even sound).

2. Amplifier, will get a clearer sound, more dynamic range, and more volume.

3. Head unit, you get another improvement, generally in clarity and dynamic range.

4. Acoustic dampening will get you a whole new level of performance.

Your £100 speakers will sound better than £750 speakers in a non treated car, clarity will increase no end, and your
driving pleasure increases hugely because it feels like a luxury car, no matter what you drive.
The music will no longer be playing over the road noise and trying to mask it. It will have replaced it.
Details previously lost in the background noise will become audible and enjoyable.

I have proven this time and time again.

With the acoustics of a car, just like home audio, you can have the best speakers in the world but if your speaker
enclosures are like shoe-boxes they will sound terrible. So soundproofing should be used on all sheet metal
areas (floors, doors, boot lid, roof, bulkhead, footwells). Then a layer of mass loaded vinyl (MLV) to dampen exterior noises.
vibrations, rattles, and most important, resonance. The soundproofing adds mass to reduce the resonance of the metal panels,
The mass loaded vinyl absorbs sound waves.

I have actually used house foam insulation panels, especially in vans and trucks.

Also try sandwiching some soundproofing/dampening and foam between the metal body panels. This will "decouple"
the speakers from the metal panels.

Using layer after layer of only just vibration dampner is a waste of time. All you get are poor results.
You need to 'stagger' the layers - 1 layer of damping, 1 layer of foam.

I'll also tell you something that no one else selling vibration dampers will -

Applying multiple layers of damper to every bit of sheet metal in the vehicle, is counter-productive and a total waste
of money. Anything more than 25-30% coverage is excessive and pointless.


If you have never been in a properly sound deadened car you will probably not understand why it is worth the huge expense,
but a well sound deadened car - no matter what car it is - Will instantly feel like a Bentley.
Once a car is deadened the sky is your limit to how good you want the sound to become.
Now ANY audio improvement you make is easy to hear and appreciate and you will really enjoy driving a quieter car.


Generally, to gain the top quality sound that you want -

1. sound deaden.
2. change head unit for a known make with RCA pre-outs, so you can add amplifiers.
3. change the speakers for some decent brand.- Component speakers preferably.

A good install usually uses fibreglass 'wool' to create custom enclosures for the speakers in the pillars,
dash and footwells, then again for the subwoofers in the boot.

Remember - bitumen type soundproofing does NOT block outside noise very well. Foam and MLV do that).

AVOID no-brand amplifiers, and any amplifier that quotes 1000 watts power for a cheap price.
Use RMS power quotes NOT the max power quotes, and look at THD values (no more than 1% THD).
I've seen quoted power figures that are total bollocks.

In car audio THD values are inherently higher than home hifi (so less than 0.1% THD are quite rare).

A fully digital 50 Watt amplifier will produce more sound than a 500 Watt analogue amplifier.
Because the digital amp produces approx 80% sound/20% heat.
Analogue amp produces 80% heat/20% sound. (approx).

A little bit like a standard light bulb and an LED light bulb. Roughly 80% heat/energy saving.

This is why digital amps are more expensive, but worth the extra outlay. They draw MUCH less current from the battery and need
smaller cabling and ancillaries. Physically smaller too. So make for a much easier install. I've heard 250 Watt digital installs
out perform 3000 watt ones. (and no need for heavy duty cables, twin batteries, twin alternators etc -
so you actually SAVE money).

Oh, and don't expect good sound quality if your source disc is an MP3 Player, iPod, USB or a computer copied disc.
Downloaded music is very poor quality.
I've had this discussion with MANY, cloth eared, people as they swear that there is no difference (Until I prove that there is).

Personally, I tend to stay away from these brands -

American Pro
Blackmore Mobile Electronics
Diesel Audio
Kole Audio
Performance Teknique
Phase Linear
Solid Audio
Sound Storm
Street Edge
Ultra Linear
XFile Audio

Too many to list. Just read online reviews and ignore the obvious 'plants'.
Remember that many firms delete bad reviews from their own websites. It's happened to me.

Avoid any other cheap Korean/Taiwanese rip off speakers/units (copies). They may look cool but sound awful.
You see eBay littered with them and, for some reason, people buy them. (Cheap prices I presume).
I've fitted customer supplied speakers and units, and winced at their sound as they screeched and hissed.

These brands, that I have used, have always proven good quality -

American Bass
Ascendant Audio
Bazooka sub tubes (in pairs)
Canton Pullman
Boston Acoustics
CDT Audio
Critical Mass 
Diamond Audio
Elemental Designs
Image Dynamics
Incriminator Audio
JL Audio
Massive Audio
MB Quart
OZ Audio
PHD Audiophile
Phase Evolution
Powerbass USA
Precision Power
RE Audio
Rockford Fosgate
Seas Lotus
Treo Engineering
TRU Technology
Tube Driver Blue
US Amps



I hope some of this was useful or interesting. If you have experienced any good quality products yourself,
then please message me to add them to my list once I have investigated/researched them myself.

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