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post #1 of (permalink) Old 21-03-2007, 09:44 Thread Starter
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Dynamat - Guide for the uninitiated

Seems more F/TF'ers are going down the upgraded audio route, judging by some of the recent posts on here, and the question of 'To Dynamat or not to Dynamat' comes up frequently, so i thought i'd compose this guide to explain what it is , what it does, and how you fit it for those that might be considering it as an option. Hope it helps

Why Soundproof?

As soon as you turn the key and start your engine, your car becomes a generator for vibration. This vibration travels through the panels of your car, which act as a sounding board, translating this vibration into audible noise.
Once on the move, other sound becomes a factor too - road noise generated by the contact between surface and tyre, wind noise etc all add to the sound transferred into the car - particularly with a rag top like the F/TF.

To combat this, manufacturers use a variety of sound deadening/sound absorbing materials, the most common ones being jute felt (the multicoloured material stuff that soaks up the leaks) and bitumen sheet (the stuff that looks like tar and turns your hands black). These are not the best available materials for the job, but they are A: Cheap and B: easily applied in a manufacturing environment, which is why they are so prevalent.

However, backing up a bit......THESE ARE NOT THE BEST MATERIALS AVAILABLE FOR THE JOB! Just because they are fitted from factory, does not mean they are much good. Manufacturers have to balance a variety of factors, so fitness for purpose is sadly not often at the top of the priorities list - its often a compromise of cost against effect and cost usually wins.....

What is Dynamat??

Dynamat is a brand name that has become a generic term (much like Hoover with vacuum cleaners) for aftermarket sound deadening. It is a thin, flexible, easy to cut and mould sheet that stops noise-causing resonance and vibration. It also acts as a thermal insulator. It can be applied to a specific panel, such as the inside of a door skin, to reduce resonance and improve the sound of speakers, or to a complete panel, such as a floorpan or bulkhead, to keep unwanted road/engine noise out.

Why bother - my stereo sounds ok already??

A good question - especially given the cost of Dynamatting a vehicle, and the hassle of doing it.
As an example, You've fitted nice uprated speakers to your doors, and they sound ok to you, but every note you play through them will pass vibration to the surrounding door panel and door skin. The sounds from your speakers will be of a given frequency and tone - this is music and pleasing to the ear (unless its country and western ), but the vibrations now passing through the door panel will be converted to disharmonic sound as it resonates through the metal. This will distort what you are hearing to some extent, so you will not be getting the best from those expensive new speakers.
Now rewind to when you were fitting the speakers. This time you apply an 8" square piece of Dynamat to the area of the doorskin behind the speaker. The doorskin is now accoustically 'dead' as any vibration passing into it will be interrupted by the Dynamat, so your speakers will sound better to the ear.
The same 8" piece in the door will also reduce road noise by3 to 6 decibels, which may not sound a lot, but the decibel scale is ramped, so its pretty significant.

What should i go for??

There are four types of Dynamat: Original, Xtreme, Dynaplate and Liquishield.
There are pro's and cons to all four - price being the main one.
I wont go into detail on each one, but here is a brief outline.

Original: As the name suggests, this was the original soundproofing sheet. Offers good sounddamping and sound absorbtion as well as a thermal layer. Supplied in sheets. Good for localised application and whole panels alike. Cost is bearable.

Xtreme: Half the weight of Original, and offers 4 x better damping rate. Used for areas where heat is a factor, such as the engine bay firewall, inspection plate etc. Cost is stinging

Dynaplate: 32% lighter than Xtreme and better damping. Also adds rigidity as two layers of Dynaplate is stronger than sheet metal (what most car panels consist of) Cost is eyewatering!

Liquishield: Same damping properties as Original, but applied in liquid form as a spray. Good for hard to get at areas, or areas where sheeting would be hard to apply.

Unless you are planning an SPL grade install, or are soundproofing a race car, Dynamat original will be suitable for most, if not all, applications in the F/TF.
A full application on door panels,floorpans and bulkeads would cost 200 ish quid, depending on wether you go for fully covering panels or just partly covering them (40% coverage on a panel will give a good reduction in noise).

How is Dynamat applied??

To apply, you will need a heatgun, a sharp knife or shears, a can of panel wipe and a small plastic roller. Its literally a case of cleaning the panel, cutting the sheet to the required size, sticking it down (its self adhesive backed) then heating and rolling it to ensure a good bond.

And thats it! There are many other types of sound deadening available - i dont want to sound like an advert for the Dynamat brand, but its the best known and most easily recognized brand, so for the purposes of this guide thats what i've used.

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