Scooby Doc

The install has gone well. Have hit a few predictable problems - difficulty hearing the sub at mway speeds etc.

However, only realised when I got home from work - 40 minute commute on mway that I felt as if I had been to a Motorhead concert.

With my current amp (Denon DCA 800) driving infinity kappa 6.5" components up front and an infinity 10" reference sub in the boot I am straining to hear some of the vocals. The subbass is not bad - you can feel it - and very frequencies such as cymbals are good but some of the vocals make me want to lean down closer to the footwell and the speakers.

Clearly this is not too practical.. The amp is able to provide sufficient volume without distortion and does not overheat.

Would dynamat help and if so where should I stick it (so to speak)?

Is this phenomenon due to the amount of road noise or is it just peculiar to the selection of music in the past 4 days since it was installed.

As always I would greatly appreciate your thoughts - NAF, Chiark and the sound engineers.

Martin

ScoobyDoo555

Dynamat might help...... however, sounds like the road noise (300hz - about 2.5KHz) is in the same frequency band as the vocals :-(

Either that or your speakers are wired out of phase (wild stab in the dark)

Let us know anyways.......

Dan

iain atkins

Scooby doc, you've got mail

Iain

chiark

I killed a lot of road/exhaust noise by putting a layer of sound deadening fabric (sort of thick, woolly stuff) in the boot. This made more difference than the dynamat...

If road noise is the problem, it's difficult to get rid of short of taking out the whole interior and dynamatting the lot. You may expect up to a 3dB reduction in noise if you do this.

Dynamat on the doors also appears to help. I think that there's about 1 sq ft in each of mine.

If your head is pounding when you get out, it seems to me that something is distorting. What I don't understand is that your amp is happy and not getting hot, so I could be talking out of,erm, complete the sentence.

In my experience, I can listen to loud, clear music all day without any ill effects, but if your ears/head hurts, something is playing louder than it's happy doing so. My first in-car effort (upgraded speakers + cd head unit) used to make my ears ring if I turned it up too loud due to the distortion...

It could be the music that you are listening to, but any type of vocals really sing out on my system, particularly female ones.

Having the speakers out of phase with respect to each other can cause frequencies to be "sucked out", so it may be worth checking that.

Also, it sounds like sacriledge(sp)?, but try changing the phase on your tweeters with respect to the midbass drivers. A friend of mine who won a few pro sound-offs confided that his tweeters were in different phases, and that he occasionally swapped phase with respect to the other tweeter. It really depends on all sorts of things whether it works or not. Suck it and see.

Do you have any speakers in the rear? If so, it might be worth a phase swap on these.

My final thought would be to have your ears grafted onto your knees. That'd work.

RockinRu: that's really interesting about the wing mirrors, and makes sense!

rockin'Ru

If you're up to it,Dynamat in the doors[front and rear] would greatly help cut down on turbulance noise from outside the car.At highway speeds,just the wind hitting your side mirrors will send vibrations through the entire door skins and add tremendous background noise.The other source is the floors,but in a newer car it's not as bad as,say,my old 89 hatch.LOTS of noise,but I also run about 1300 watts rms so it's not noticable at half volume.

DAZ 4

I think the boot area is the biggest problem, You try driving any distance with your back seats pushed forward.

I had a shock when I got caught in a downpour last week, it sounded like someone was dropping nails on my boot. Dynamat on the underside of the boot ??

chiark

Dynamatting the boot lid makes an unbelievable amount of difference. I swear that Dynamat should use it as a demonstration of what the stuff does.

Instead of a metallic "twaaangbdrrrr" (like a metal ruler on the side of a desk) it goes "thunk"...

Scooby Doc

Dan, Iain, Nick, RockinRu, Daz 4

Thanks guys for your thoughts

The vocals certainly do not jump out and thus I wonder whether you guys might be right about the speakers being out of phase. If you want a job doing properly - do it yourself. I shall pursue this at the weekend.

The road noise is intrusive and obviously I don't have quite as much power as RockinRu - I was across on the west coast of Scotland at the weekend and I thought I could here your install RockinRu! - but I don't have distortion. The reason it was soloud was because I couldn't hear the vocals - humph!

I think some soundproofing is in order. Iain - you're not impressed by Dynamat. What do you guys think - simple sound deadening material just as good.
Sounds like Dynamat on the under side of the bootlid and sound insulation felt on the boot floor with some more dynamat in the doors.

I'll let you know how I get on.

Many thanks again for all your help

Martin

Scooby Doc

Nick

I thought I had forgotten something - I have the standard rear speakers in run off the head unit but the are virtually faded out. I am keen to remove them and vent the bass.

What have you done in the back Nick? I think from memory you are using rear speakers to keep passengers happy.

Martin

chiark

Martin,

Re: speakers...Spot on! Left 'em in as it keeps people happy.

Dynamat is good, and there's other good stuff available too. I've tried Scosche Accumat which is around the same price but is thinner and seems to stick better. Dynamat's adhesive isn't the best and your car will stink of meths for a few days

rockin'Ru

Scooby Doc,there's a couple of cheap equivalents to Dynamat at the hardware stores here,but don't know if it's available there.Sorry,can't remember the names,read it somewhere a while back.It's for roofing.
And also,the 1300 watts is the rms rating of both amps measured at 12.5 and 12.9 volts from an HU that puts out 4 volts per pre-out,and the gains are properly set.I run 14.4 volts so the dynamic power output isn't even included,and there is NO distortion at 2/3 volume and a hint at 3/4.It's not what you might think...

chiark

Rockin': I tried that stuff in an old fiesta! It works pretty well, but the trouble was when it got hot in the car the stuff would detatch itself. Just like Dynamat then

Bitumen is the stuff, I think, with a self adhesive backing. I bought a roll of it (about 4 inches wide, 10 feet long) and did some of my car panels. Cheap and cheerful, just be careful of the adhesive...

If using any stuff, you need to clean the surface that you're attaching it to very well. Meths is good for this. In the scooby doors, there's some sort of wierd stuff applied already which needs to be removed to get a good stick in my experience. Meths did shift it.

Mark_S

I used Brown Bread in my front doors, looks like thick bitumen with a layer of soft aluminium on the outside, quite heavy stuff. Sticks like sh*t to a blanket especially once youve had the hair dryer on it!. Recommended by the guys at Incar, he said it was a cheap alternative to Dynamat. I couldnt say how they compare though.

I used two layers, noticeable difference.

Nick where did you get the wooly stuff for the boot from?

chiark

Mark_S: my exhaust was wrapped in it! It's like very coarse felt (feckin felt ) that's about half an inch thick and tears by hand.

I had enough to put two layers in the boot, and it muffles the sound quite well. Certainly it's a lot less harsh sounding.

As for where to get it from: not a clue. The only other time I've seen stuff like it was as soundproofing in a ford fiesta...

Moss

Try BJ Acoustics. They mainly specialise in sound proofing kits for Land Rover's (now they are noisy!) They sell all materials for sound deadening separately though and it's very good gear, particularly 'spacelayer' and 'barrier mat'. Check out their website...

chiark

Excellent idea: bjacoustics have been around for years, and I've yet to hear a bad word about them...

(no doubt someone will correct me after a statement like that )

Scooby Doc

Thanks for your post

Have you or anybody out there stuck in soundproofing in places other than the doors and boot?


Lifting carpets sounds like a nightmare.

Martin