I have measured the DB reduction of my 2004 CE coupe with the Dynamat Extreme install vs. stock. The DB reduction was only 1-2 DB. At speed, the reduction was hard to document.

Then...I added B-quiet's Vcomp...and the car is much quieter. Unfortunately, I did the B-quiet install after the winter set in in Ohio, and have not been able to remeasure the DB reduction yet. I will, and I will post the results here.

Here's a link to my B-quiet install photos...

http://forums.corvetteforum.com/showthread.php?t=989605

 

I used Dynamat in my 73 TransAm 455HO with 3.5in. pipes and it helped greatly. Just a little sticky and tricky at points, but all together well w orth it.

 

I've just got one question here, folks. Given that our cars have a 400 pound maximum payload rating, how much weight does each of the materials described here, applied in the recommended amounts, weigh? I'm finicky about that because when the wife and I travel with our luggage, I would bet we're already pretty close to, if not over, that 400 pound limit. ET and Mike, I'd like your input on that, too; it is greatly appreciated.

 

I've had several Corvettes over the years, beginning with a '58 in 1969 and culminating with the '02 and '99 we have today. It truly amazes me how people buy these later generation cars expecting them to be equivalent to a Lexus or Ford Crown Victoria in ride quality and interior noise level. It's still a sports car and if you know that going in your expectations should not be altered.

 

I just put in my 50 Cent cd (pronounced Fiddy Cent), and crank up In-Da-Club. Road noise is gone.

 

Part of my mission was to quiet the tire noise and reduce heat in the cabin, the criteria was: inexpensive, light weight, and easily reversible.. the Frost King and reflex, with batting add less than 15 pounds, compared to other more dense and tar based products that are expensive and heavy.

 

Why easily reversible? And if that weren't a criteria, would it have changed your findings?

 

People who want to mod their car are sometimes afraid to jump in with both feet, some mods do not turn out as well as expected... so being easily reversible, makes testing different things easier... This was a government project, not a GM project... Gm already made the commitment to reducing weight without any regard for noise..
I did not want to epoxy or spray any insulation. I am sure there are better noise canceling materials... but they are not as light weight and as inexpensive... My research on the original dynamat , was this it gave off a tar smell when heated... it was too heavy, and too expensive.. so I never tried it because it didn't meet my criteria. the tar smell was just another negative.. I heard the new stuff is better... I did this research while I was still working, four years ago.

 

But without doing a DB test your research was nearly useless. Without the DB test there is NO WAY to tell how well the mod worked. You mention heat....did you measure the tunnel temp before and after?

 

I agree the only true way to measure noise reduction is with a docimeter. But in lieu of that, one can tell noisey from quiet with their own ears, especially if you travel over the same roads.

You'll notice the folks who achieved the most noise reduction were the ones who did not use metal faced insulation.

Walk into a recording studio and the only metal you'll find will be the instruments. Everything else will be covered in foam.

 

you need to learn the difference between lowering the resonate frequency of a vibrating panel - and absorbing sound. Two totally different avenues for two different applications of sound reduction.

We're stopping outside noise from being radiated inside ... not absorbing the sound that is already in the cabin.

 

over what frequency range?

DB meters can fool you. If you reduce 50% of just a portion of the audible spectrum - you DB meter (that is looking at a much broader range of frequencies) will not indicate a 50% reduction.

If you reduce the most irritable band (range) of audible frequencies (just a segment, and not a reduction of the entire audible range) - that can make the ear happy (where the DB meter says there wasn't much of a change).

For example; lets say you run an accurate recording of interior car noise into an amplifier with top-notch speakers in a recording studio room.
But instead of a single volume control on the amp - there are 4 volume controls.

#1 is for the 20 to 500 hz range
#2 if for the 500 to 2500 range
#3 if for the 2500 to 8000 range
#4 is for the 8000 to 20,000 range

So you turn them all up fully and the sound out of the speakers acurately simulates normal interior car noise.

But in this example the most irritating noises inside this car are from the 100 to 400hz range. I don't necessarily mean the most "loudest" noises.. but the range of car noises that are most irritating to a person.

So you turn down volume control #1 by 50% (this was the volume control for the 20 to 500hz range) and the irritating noises are cut in half. But the overall volume is only cut by 12.5%

Your ears can easily hear the difference. The driver is much less irritated, the passengers are happier, but the DB meter shows a lousy 0.3 db reduction.

Having possession of such an instrument (DB meter) is just one step. Knowing what it does, how it does it, how to interpret the results, and when to know it's being fooled - goes a lot deeper than just having one in your possession.


.

 

Then why not use a RTA in the car? That would tell you exactly what frequency were reduced and by how much. Point being...no real tests have done and advertised. This question has been asked so many times and usually the question is ducked. Mike you have responded but I have yet to see ET respond. In my honest and professional opion it is like selling snake oil. I am not saying it does not work, I am asking how well does it work. Just like anyone should that is interested in taking the time to do this mod.

 

Don't know if I can agree that the most annoying frequencies would be in the 100-400 htz range. For the most part you are talking about the bass frequencies. The studies I've seen indicate the frequencies in the 500-4000 range will cause more pain. The mid range often adds what I refer to "mud" in a sound system. However I will say that the super low frequencies can cause fatigue especially if you have the vloume cranked. That "Boom Boom Boom, will wear you out.

For most running the factory Bose in your car, you know that there is not much frequency control. I would have liked to have seen a separate "mid" control. If you are like me, I suspect you have your bass boosted and treble cut to close to the halfway point on the Bose.

Although I have been involved with sound for 30 plus years, I will leave the factory radio in the car. My 54 year old ears are not as good as they use to be.

 

ding.. ding... ding we have a winner !!!

but who has the time and money to fool around with this?

With us Corvette owners - added weight is a serious concern when adding mods. And spending money for a mod that won't increase HP is not popular here. Both ET and I have found alternative light-weight low-cost products that worked well for us, and have countless from all others who have tried the same products (others that share our same goals and concerns).

We both know there are better products out there and have recommended them to those not concerned about weight or cost.

Yes the FK and Reflectix may not work as well as others... but it's about the best one can do when lining the entire interior for 15 lbs of added weight.
Yes, it's a trade-off (lower weight and less $ for less results - compared to heavier and costlier products). But it is what many Corvette owners are seeking.

If you seek other goals and have different restrictions/concerns - great then. Find the best products to fit your criteria.
No one here is coming down on you for your choices.

 

Hey...I resemble that remark...

Peace
Willfulone

 

I don't dance when you pull strings... anyone who knows anything about frequency response knows what some people find pleasing , other may find harsh harsh... volume is still another concern, black top, vs concrete present two different areas of noise... You see I was doing this for me... and no one else.. I was not out to be a hero or produce, defend or ram this down anyones throat... I did this in 1999, for my own purpose.. the car was noisy, I knew the car has no insulation, and I knew where I could improve on tire resonance.. when things are noisy you put in ear plugs.. you try different things to effect a change in the cabin. I tested different materials using GM's guidelines for interior compliance.. using an environmental test chamber... to test for heat and humidity under accelerated cycles.. all GM interiors are FMEA tested to 160 F for form fit an function,.,, when I came here to this forum in 2001 People were complaining about excessive tire noise... I offered a solution in private... to a few people.. Mike was also experimenting with some things... I offered him my help in private... he used some of my input with his own and developed a "Forum guideline" so others could use this , try this , or let it go... what I did , I did for me only... it just evolved into this over the years... if you do Not like what I say or do on this forum there is a simple solution, and I have tested it fully and it works... its called "IGNORE"... you simply open up the ignore program, and type in my screen name, and you will never have to listen to any of my drivel, I do Not have to defend anything I do or offer here.. you can use it , or you can ignore it.. Ive not held a gun to anyones head... if this is just a placebo.. and people are happy with the results, thats all that counts... no data, no test strips.. no blessings from the Pope....

 

I bought my Vette for speed, and speed is what it gives me. I've driven an Lexus LS400, its an awesome car. So quiet you can barely hear any outside noise. I also have a boss that has a Lexus RX330. Also a nice vehicle. Luxury cars are quiet, Corvette's kick a$$. I don't see how you can do that quietly.

 

Well good for you. I am happy that you are happy with your car. Fact being many moons ago I asked a simple question. How well does the mod work? Never got an answer...still have not gotten an answer. Seems very odd to me for someone to have done such extensive testing to not be able to answer that simple question. If the first time I asked the question an answer was given then all could be avoided. I would love to endorse using Frost King for noise reduction but not until it is proven that it works.

I do not use ignore feature. I have seen plenty of your posts that are worth while and informative. None on sound proofing though.

As for the time and money. Ding ding...I have made the offer many times. To anyone within a reasonable distance that is going to do this mod anyways. I will use my Audio Control RTA to measure the car across various terains if needed at various speeds before and after installation. I would actually do it on my own car if it was not already sound deadened with Stinger Road Kill.