Experiment In Soundproofing The 205

[kyepan 291]

Allo there,

 

For two reasons i would like to reduce resonance, vibration, and conducted noise within my car.

 

1) I would like to be able to hear my music a bit better

2) The perceived speed within the car is higher than the actual speed, at "70 it feels like a hundred"

 

Based on a bit of searching on here it would seem that this is based on the following issues.

• Resonant and conducted exhuast noise conducted through the boot floor and transmission tunnel.
  
• Tyre noise through the rear arches - less so through the fronts as bulkhead insulation almost covers them.
  
• Resonance from road noise coming through the larger panels on the floor.
  
• Conducted road noise coming through the floor.
  
• Resonance of the rear quarters / door skins..
  

cancelling the noise out seems to be about (based on what i have read and discussed with Anthony)

• Reducing the frequency at which the panels resonate from a frequency similar to the engine to something much lower. Lower frequencies are perceived as quieter than they actually are.
  
• Blocking noise with a barrier that turns the sound into heat, something that again drops the frequency down to something much lower then a surface that converts the sound energy to heat (the foil on the foil backed bitchemen heats up)
  
• Stopping the retransmission back to the air on the other side by using a blocker (foam)
  

As with most things on my car, the budget for this is 74 quid, for that i have 10 sheets of acoustic dampener from carbuildersolutions 500mm x 20mmm 40 quid

and two rolls of 225mm x 10m flashing tape from screwfix. 34 quid

This will also be used to sort out the audio install i am doing at the same time.

 

 

I wanted to get some expensive closed cell vinyl / butyl high temperature oil / fire resistant closed cell foam but that was 70quid for a 2 x 1 m sheet.. and would blow my budget

 

Reading up there are two schools of thought on dynamat / soundeadeneing, material

 

1) cover everything - expensive

2) use small squares and diamonds and shapes on the larger surfaces to drop the resonance and dampen vibration

 

 

Places to use the acoustic dampener (making it go as far as possible)

 

four sheets used on front doors

• Around the speakers front and back
  
• small shapes on the inner door panel where tapping it resonates.
  
• circle on the outer door skin behind the speaker
  
• length along the bottom of the outer door skin
  
• Two patches on the upper section of the door ski
  

 

 

 

Two sheets for the rear quarters / wheelarches

• Shapes in the front rear quarters above the trim line,
  
• patch below the trim line
  
• squares and shapes on each of the flat sections of the rear wheel arches
  
• lengths over the rear wheel arches internally and between the outer / inner skin
  

 

 

 

two sheets

• Patches in the driver/ passenger footwells / rear floor pan where tapping it sounds like a drum
  

two sheets

• around the rear speakers
  
• behind the rear speakers in between the gti badge indentations
  
• patches on the outer rear quarters skin.
  

 

The flashing will be laid in the following locations

• Boot floor complete
  

• floor pan complete except exhaust tunnel and near to the bulkhead where the manifold is (anywhere that is likely to get hot)
  

• Inner rear wheel arches complete, including between the skins
  

• Inner rear quarters front complete
  

 

 

with a bit left over.

 

 

old interior out - to be replaced by the Sorrento half leather

 

 

inner trim removed ready for soundproofing

 

New trim turns up

 

 

The difference... well, I would say more than just noticeable, it's an order of magnitude better and for the price / weight (about 5kgs). Thoroughly worth it. The speakers also sound better obviously, much sharper cleaner sound with less noise.

 

road noise is markedly reduced (although i think this could be improved with some foam)

Resonance is very much reduced, the exhaust sounds quieter and does not peak as the revs pass through resonant zones with the body panels..

It feels slower.. even when it isn't.. it feels much slower!!!

 

I did take an original uncalibrated reference volume of 89DB at 70mph using an app on my iphone. I'll do that again in the next day or so to double check.

 

 

Lastly, would like to say a very great thanks to paul and Anthony for giving up their time to help me do this.. its made a shocking difference to the sound.. basically you hear the engine, and the music, but much less resonant road noise / exhaust noise. The doors when closed... also sound like .. well not quite like golfs, but not like peugeots thats for certain

[Tom Fenton 1,525]

How much weight has this added? Surely the car will be slower even if not by a noticeable amount due to added weight.

[timmsy19 3]

Says 5kgs in the last bit of post

 

Even given the added weight and potential for it to slow you down (marginally) its probably such a worth while thing to do. It'll be the first job on the list for my next project

 

Thanks for the write up kyepan, looks like a job well done

Edited February 29, 2012 by timmsy19

[Cameron 16]

I have a bulk pack of Dynamat Superlite on order, cost £134 for 48 sqft which isn't too bad!

[Anthony 1,000]

Lastly, would like to say a very great thanks to paul and Anthony for giving up their time to help me do this.. its made a shocking difference to the sound.. basically you hear the engine, and the music, but much less resonant road noise / exhaust noise. The doors when closed... also sound like .. well not quite like golfs, but not like peugeots thats for certain

No problem - to be honest though, it was Paul that did most of the graft

 

Be interesting to go out in the car now that you've done this work and see how different it is, as I had been planning on doing this to a lesser extent on my own car given it is being built primarily as a road car. Having only done the boot floor on a previous 205 (one Happygoron now owns) even that made a difference and took the edge off the exhaust drone, and for very little weight penalty / financial cost.

[kyepan 291]

Yep, a spin is most definitely required!

 

On a slightly related note.. the stereo setup.

 

I bought a decent head unit with 18w rms per channel , and some front components which are about 30w rms - they are however distorting quite a lot when being driven from the head unit. Cutting the base out seems to have cured that. My reading tells me i need to figure out how to use the high pass filter on the fronts and rears to do this a bit more intelligently.

 

then..

 

If the head unit RCA output is not affected by the high pass filter i can run the 6x9's in full range - i may turn off the head unit amplifier and play around with what comes out of the RCA to decide this.the amp also has a cross over i can also use, but it only goes up to 120hz (i think), it could be a low cut actually i can't remember.

 

If not i'll have to run them as a "sub" and use the low pass filter that is integrated into the sub out.. and turn the amp cross over / cut ..off

 

 

advice from stereo heads welcome.

 

PS yes i am using 6x9's instead of a sub, as i don't like the boomy crunchy bottom biscuit base base base.

Edited February 29, 2012 by kyepan

[Anthony 1,000]

Does the headunit have a sub-out? That's the usual way of doing this IME assuming you're not running all channels through an amp.

[kyepan 291]

it has a left and right single RCA out, with a software setting to determine if that's a sub or not.. i think.

Edited February 29, 2012 by kyepan

[jason7579 5]

If you have 2 RCA outputs one is normally for fronts and one for rear/sub, this is so when adjusting the staging on the head unit the amp will pick up on your inputs. (I believe) What head unit do you have?

 

If the cross over cuts at 120hz I would imagine this is a high pass filter as human hearing ranges approximately from 20hz to 20,000hz (20khz) the bass range being roughly 20-140hz

[kyepan 291]

alpine 133bt, sorry i was a bit unclear, it has one pair of rca outputs! ie two plugs.

[jason7579 5]

On mine I only have 1 pair of RCA's and it works with the rear speakers, if I adjust the headunit to bring the sound forwards the amp and sub will get lower with the rear speakers.

[MiniGibbo 142]

good read, i done the complete oppisite on the weekend just gone lol...

[kyepan 291]

good read, i done the complete oppisite on the weekend just gone lol...

 

Soon you will be deaf!

[Paul_13 212 1 Cars]

Soon you will be deaf!

 

Like me, you'll soon want the sound deadening back in asap! I'm in process of putting back in

[pugpete1108 62 1 Cars]

ive just done this in my car using flashing for the whole floor and firewall, i plan to carry this on with all the outer skin panels along with that i have this:

 

closed cell foam for the whole floorplan and up the firewall i have accoustic foam, which includes the underside of the whole dash and other front plastics. i may use some more of this in the rear arches too.

 

 

[shalmaneser 26]

You've convinced me, I'm gonna do this to mine I think.

[pugpete1108 62 1 Cars]

You've convinced me, I'm gonna do this to mine I think.

 

Who me?. Just don't hold me responsible if it spontaneously combusts.

[Baz 421]

Would be interesting to know just how much weight this is really adding and thus, for me anyway, if it'd be worth it for even a 205 'road car'.

 

Given most of my 205's are geared towards performance and are just toys these days, to me in a way it's backwards engineering; you've put a bigger, more powerful engine in a little hot hatch built in the 80's that's iconic for the way it goes & handles. Adding more weight is only going to be detrimental to that of course! And the noise is all part of the experience, earplugs are useful for longer journeys!

 

Joking aside i can completely see where you're coming from and it makes perfect sense, especially if you carry loved or less understanding ones around in it! Interesting read!

 

BTW for reference, 'bitumen' 'bass' & you owe me money punk!!

Edited March 1, 2012 by Baz

[Cameron 16]

Like me, you'll soon want the sound deadening back in asap! I'm in process of putting back in

 

Mine came with it all removed, not only is it loud but in winter it's freezing! The carpet doesn't fit properly either!

 

On the subject of weight, both cars I've removed the OE sound insulation from it's been soaked through and weighs a tonne! If all 205's are like that it's probably a pretty good weight saving.

[pugpete1108 62 1 Cars]

i did the stripped out thing and tbh i feel im getting a little too old for all the noise

 

besides i'll offset the extra weight with a set of bodies. brum brum

[kyepan 291]

Well... like i said 5kgs, plus the weight of the parcel shelf and amp, so perhaps ten.. and then the half leathers - i'm not sure what they equate too.

 

Baz- I think you're right it does sound and feel less quick now.. so beware if you want the visceral experience .. perhaps something else noisy can put that back into the mix at a later date...

 

Set up the stereo last night, and well.. i don't want to blow my own trumpet, but it works perfectly. an received positive comments from the guys who were in the workshop where i was fiddling. the 6x9's filled the bass line well, with a 120 high pass, and 120 low pass on the sub output.. Not boomy, just follows the bass line and fills that area of the spectrum.. Doof Doof is not the way forwards.

 

The remote wire managed to fall off this morning / strip itself, so i think some cable securing needs to happen under the shelf, as my boot tidy moved.

 

But ultimately the project to soundproof and seems to have been cost effective and successful, and the battery charger appears happy, with green LED's.

 

Cheers

 

J

[Richie 32]

Interesting read. I think i'll be doing something like this to mine.

 

I used dynomat on my last 205 just on the boot floor and it was more pleasant on the motorway.

[harryskid 193]

Why not save all the hassle and just buy a rolls royce !

[Cameron 16]

Recieved my box of Dynamat Superlite yesterday, 48 square feet is a lot!

 

The whole pack weighs about 6kg, equivalent to about 7l of fuel or a handful of tools. Not exactly heavy and when evenly distributed around the car like it will be, I can't see it making an ounce of difference to the handling.

 

I started fitting it yesterday in a similar way to how you've done yours: complete coverage on the inside of the rear quarters, rear wheel arch liners and the boot floor, semi-complete coverage under the rear seats, and some squares here and there to deaden things like the B-pillar supports.

 

I'll go on to add some parts to the upper rear quarters, rear speaker surrounds and the boot side of the inner rear wheel arches. Then on to the full front floor, wheel arches and firewall, and some bits on / in the front doors.

 

It's already made a fair bit of difference, when I fix my nackered exhaust and front wheel bearing it should be even better.

[MiniGibbo 142]

My carpet has sat down well with no sound deading?