Firstly let me say I have no affiliation with Focal,
or am particularly biased against any other products,
I just happend to try Focal plain chant, and thought I'd let you know how it went.



What is Plain Chant?

Plain chant is accoustical Damping Plates,
they come in a box of eight, and are approx 4" wide, 10" long and 1cm thick.
Retail $99.00 a Box incl GST. ( I got 2 boxes for $180)

Purpose?
1. To remove accoustical resonances from Metal surfaces.
(Has thick Tar Like backing, like Dynamat, but thicker)
2. To Absorb part of the Standing waves from Midrange or Subwoofer Speakers.
(has thick special type of Cell foam for this)

Standing waves are the returning wave of sound or otherwise from the speaker when it attemps to return to centre after moving forward to play a particular sound. The trouble with Standing waves is they bounce off back walls of doors or speaker boxes, and bounce back at the speaker cone, Either Colouring the sound of the speaker, or introducing distortion at higher volumes, in most cases both.

Test Vehicle:
BA Falcon Ute
Focal K2P Midbass/splits
Focal 27kx Subwoofer in 22 litre sealed 18mm MDF box

I originally purchased these for my Subwoofer,
I bought 2 boxes, as suggested by Focal Australia,

My sub box is quite square, so the potential for Standing waves was high,
The Focal Sub is very precise, so any problems where noticeable, I wasn't happy with the output,
so I was looking for something to improve it slightly, so I thought I'd try plain chant.

I fitted 8 Squares to the inside of my box, 2 at the top, 2 on the left and 4 on the back wall, I left the other walls free of them, if I could afford another box I would fill it up, but the waves can only bounce once in any case with 3 walls covered. so I figured I'd try it like this first. I only fitted myn with Double sided tape, since the plain chant would not be doing any Sound deadning in the sub box, I didn't see the point of sticking it down permanent, This way I Can use them in another box later. Or in another cars doors.

I put the sub back in the car, and turned it on and listend to a few favorite tracks, I've been listening to the sub for about 2-3 weeks and had a pretty dam good idea what it sounded like before.

Initially the difference was noticeable, and the more I listened the more I could tell something was different. Distortion I didn't think was there before, I realised it was, because the sub was so much clearer all of a sudden, I had tried filling with dacron and running without, but neither where like this. Low end response was smoother and the bass was more detailed, Although I did notice some of the THUMP it had seemed to have smoothed out slightly, and now the bass is more realistic to listen to. Instruments sound more alive.

Summary,
Installing plain chant in the sub box decreased Distortion by removing part of the rear sound wave (standing waves) the Frequency response was also smoothed out, and overall sound quality was improved noticeably.
Output was increased due to lower distortion.
--------------------------------------------------------------
I still had the spare box,
I decided I'd try it on my Focal K2P splits, behind the midrange. This of course is the actual purpose of Plain chant, so I figured it was worth a Shot. I've been listening to my K2p's for over a year, and know exactly how they sound , each little noise, note and instrument sound they make.

My doors have 2.5 metres of sound deadning in each, so I wasn't really interested in the deadning qualitys of plain chant. Moreso in the Standing waves department.

Fitting:
I used the adhesive backing this time, I had no plans to remove the plain chant,
in my doors there is a great big 5-6mm wide Round Bar runs staight across where
the back of the speaker would be, this was no problem the plain chant wrapped around it nicely,
I fitted 4 pcs per door behind my speaker midrange. The Plain chant was very sticky
and aheared very well, did not need heating or anything like that, and was very flexible
over odd bumps/curves.

Listening:
Once i got the door back together,
I put on some favorite tracks, the tone of my midbass had changed dramatically,
there was a serious increase in the 80-500 hz range, the overall midbass was much much
smoother, again distortion I didn't think was there before, it was because it was gone now.
I know that sound wierd, but the overall sound was much clearer and cleaner, and frequencys I didn't know I had where now there, detail in the midbass had improved dramatically.
The tone had changed so much In the end I had to alter my EQ Settings a little bit,
not to make it sound like it did before, but to just make it sound smoother as I now had a big
boost of lower to mid frequencys.

Summary:
Installing plain chant in my doors decreased distortion by removing part of the standing waves,
and improved detail and clarity to my Focal K2P speakers in my install. A well worthy $90 spent.

Notes:
I'm gonna look for a similar Cell Foam on it's own, to complete my sub box,
The Tar deadner on the back of plain chant is really going to waste in a sub box, so I figure if i can find that special foam on it's own...

Let me know if you also had experiences.

Juls

Got a close pic of the foam? I am looking for the something similar and have a few suppliers at work who do acoustic insulation and the like.

James

i wouldent have worryed so much in the sub box, you wont really get any standing waves in a sub box due to the low frequencys and size of the sub box.
i would have just gone down to clark rubber and got some acoustic foam and used that if you needed too, would have saved you a crapload of money.


but good review anyway. andgood to hear that you had a big improvment for the mids!

what you are talking about are reflected waves not standing waves.
peace
Cyberpunky

http://www.jaycar.com.au/productView.asp?I...eMax=&SUBCATID=

good to see you have noticed a difference.

can't say i did when i added 2 per door in my setup.

yeh your supposed to put 4 in per door,
my local car stereo shop said they use 3 per side in the installs they do. (in which they obviously charge the customer the whole packet no doubt)

I can't see how 2 would help anyway, it's not wide enough to capture the standing waves.

If you don't have the other 4 pieces, maybe grab a pair of Dynaxorbs they are $40 a pair I think,
and stick that directly behind the speaker, and the plain chants either side?

it should make a difference, unless your speakers are mounted heavily on a angle.

Juls

EDIT: LOL then reads signature and post qty... well it must have done something if your winning comps ..

Dude, please tell me you joking about saying all of the above to Shiny Car

I wouldn't waste my money on name brand stuff, but generic sound dampening products they'll cost ALOT less and do the same job.

I'd say your almost definatly right. but then you spend $900 on speakers, $1500 on a amp to run them, $300 deadning the doors, $1400 on the deck to run them.....

Then skimp on the no name brand dampending product?
I know I feel uncomfortable with that idea.

then again on some $300 speakers, behind a $300 amp on a $800 deck.. that logic is 100% perfect.

maybe he dont know?

could just read his sig

Rob, that excatly where I was heading

Don't really want to cause too much fuss..

These products would be almost useless below 1200 Hz, except for their dampening ability or possibly reflection increase.

On these last two area's there are some well proven products that do either of these.

Having tiles behind a drivers are supposed to diffuse the sound wave.

Diffusion studies and there applications is fast developing phenomena from a technical stand point.

Have a look at some of these products to gather an idea of what modern diffusers should resemble.

http://www.rpginc.com/products/diffractal/index.htm
http://www.rpginc.com/products/flutterfree/index.htm

There is an excellent article on this in
The master handbook of acoustics
by Everest.

The write up on dynaxorb must surely be one of the poorest.

DYNAXORB

Appearance:
Black, advanced polymer square

Thickness:
¼” (6.35mm)

Weight:
0.34 lbs. per 6-1/16” square
(168 g per 154mm square)

Hardness:
<10 Shore A

Density:
69.6 lbs./ft3
(1120 kg/m3)

Rebound Resilience:
<15%Tensile Strength

Water Absorption:
None

Storage:
Store in a cool dry place

Recommended Adhesive:
Cyanoacrylate adhesive


Description:
Dynaxorb is black, energy absorbing, and sound diffusing advanced polymer square. Dynaxorb eliminates Speaker Back-Wave Noise and Distortion. Dynaxorb eliminates back-wave speaker distortion that colors sound and confuses imaging by using a combination of energy absorbent material and the technology known as “faceting”.

Acoustic Properties:
Back wave distortion, a common problem with every speaker, occurs when your speaker sends the same sound out the back as it does out the front. If this rear sound wave energy is allowed to bounce back and return to the speaker, it interferes with the speaker’s ability to operate properly causing back-wave speaker distortion. Dynaxorb eliminates back-wave distortion using Sonic Stealth Technology. Dynaxorb absorbs, diffuses and attenuates the sonic energy directed towards it. Removing back-wave interference from the speaker allows every speaker to produce the full quality potential it was designed for.


Applications:
For automotive use, Dynaxorb is most effective when installed behind speakers and inside subwoofer enclosures. When used with car speaker door installation, install Dynaxorb to the panel directly behind the speaker. In subwoofer enclosures, use multiple Dynaxorbs to line the enclosure wall that is directly behind the subwoofers. For home/home theater use, use Dynaxorb behind in-wall installation speakers and inside speaker and subwoofer cabinets. Lining Dynaxorb behind in-wall speakers will not only eliminate back-wave speaker distortion it will also decouple the sonic energy from the in-wall speaker reducing the unwanted sound radiated through the wall into the adjacent room.

Installation:
Dynaxorb comes in 6” x 6” squares and can be used individually with smaller speakers or tiled together to line the opposing wall inside subwoofer enclosures.It can be easily attached to any given substrate with a cyanoacrylate adhesive. Dynaxorb can be trimmed to fit using a knife or scissors. Remove dust, grease, moisture and other foreign matter from the application surface. For best results, treat the area behind the speaker with Dynamat Xtreme then install Dynaxorb directly over the Dynamat.

The bold is mine.

I would HIGHLY doubt this quality on anything below 1200 Hz.

The focal shows no signs of being able to do any better.

We know what size and shapes of diffusers can achieve, these are not in the game.

Save your pennies.

If you want to reflect a wave use a material suitable for those frequencies.. (glass or ceramic)

Dampening I am sure most of you would have some good product (proven) recommendations.

Diffusers look somewhere else

Meh worked for me.. I don't care if it's technically or theoretically possible or not.
an article written on the internet or in a magazine by a individual including what I have put above
doesn't really mean anything.

it physically worked for me,if thats technically or theoretically possible it doesn't matter.
physical evidence overules people who write down on paper and then make up stuff in there heads based on that alone.

I used the Jaycar "Premium" acoustic foam (male and female parts) and it had exactly the same effect on Bass / Midbass like Juls described for the name brand product.

I guess anything which is irregularly absorbent will 'deflect' the rear wave and help reduce the possibility of a standing wave.

note: a standing wave in a door, approx 6" from woofer to outer skin, is around 600Hz (in my door anyway)

yeh thats cool, I'm gonna try that out in my sub box, instead of the plain chant.
the plain chant made a big difference, but it seems kinda overkill.
I'll see if that stuff has the same effect.
thanks for the reasonable response

is that for the subbox or the door ?

If sub, do you need to take the foam into consideration when measuring the volume of the box ?

You can use it in the door or the sub box,
when you put it in the box, yes you have to take it into consideration when measuring volume.

IE: don't use too much.

you can cut it into like long 2.5" wide pieces, and leave 1-1.5" air gaps between each piece
that helps not take up too much room.

I'd use the thinner of the 2 available in a sub box if I was gonna try it.

I'm not sure how much you would notice a difference in a sedan.
I'm in a ute cab, so I'm basically got my ear within 40cm of the subwoofer cone,
possibly easier to tell a difference.

Juls

Interesting view point,


Simply wanted to put across measured results under test conditions.

I guess it comes down to the human ear against verifiable measured tests.

The human ear and its associated memory limitations are well documented.

I suspect the physical tested example of a duffuser in the previous post don't rate as "physical evidence".

stop trying to confuse people too much Abmo, it worked for the guy and he's happy with his results..

yes its good to point out good reference material, but you don't have to point out that theoretically shouldn't work when in this case it has (or pyscho acoutsics has rolled the dice again..) - he's happy, and you and i both haven't got any closer to finishing our cars as we're on the interweb so get to work!

I'm off to the garage - laters

I was trying to explain the reasons he may have got some benefit,

Dampening
Reflection.

And that it may be cheaper and better to use other well tested sources for this benefit.

Diffusion was not something he or anyone else in this application would benefit from.

The examples I used should of given some indication of the shear size necessary to accomplish this, let alone the complexity required even at those dimensions.

It is possible that they may help with diffusion on a mid range, but I see am yet to see any tests done to prove this.

A six inch wave is approximately 2200 Hz.

theory and quoting websites are all good but none of it is better than real life experiance.
good on juls for getting out there and doing it. (personly i think he did it the expencive way but eh)

Ambo, if you want a more theoretical debate on how the chant "should" or "shouldn't" work then start a new thread, but don't bog down someone elses stuff..

and Rob, he theorises because thats the way he is.. always researching and trying to understand to get to his audio nirvana.. its not a totally bad thing except when he tries to start it up in someone elses thread (spam whore..), but then again i can't exactly remember how much his bonnet weighs due to his form of SD.. (lead, dynamat extreme and i'm sure something else )

just remember adding mass to the inner door skin directly behind the driver should give some benefit to a degree.

a bigger benefit to a midrange unit is NOt to have a wall behind the driver that is parallel with the driver facure. Top loud speaker designs are based upon the midrange unit having an internal cavity (ported or sealed) with the innner wallls being setup with no parallel sides. Sorry bad explanation but the results are measurable and benefitial.

I haven't actually even bothered putting any "dampening" product in my doors except deadener to reduce resonance. Oh, and I have $1999 speakers, $999 amp, $360 deadener, and $1699 head unit.

I think it's just the placebo effect, but if you are happy with the results, that is all that matters

Depends on the type of speaker, Dyn are considerably hard to set up compare to other brand, thus requiring more dampening stuff. With proper technique acoustic treatment doesn't have to get expensive.

You seem to have a strange view of spam.

His thread is about HIS opinion of the said product, and how evaluated it.

I posted my view of the said product, and how I evaluated it.

In this day in age, it appears measured testing has little or no hope of saving us from being parted from our hard earned cash.

When can send people to the moon, divide atoms but the hearing test is well above any of these "advances".

Sure electrical mechanical measures can't tell you if a painting is good to behold, or a piece of music is going to be "delighted in".

But can they tell you changes?

The vast majority of threads are ..

I like this sub woofer over that one...

Taken in that light my post is hardly "spam"

He liked the product,
I thought it is snake oil.



Hope you put yourself up for the drugs testing systems.
Personally I would rather see the tests done and evaluated before I would allow them to give me a "real life experience".

Each to their own...

No, it is not that simple.

Adding absorbent material actually makes the box appear as much as 10% larger acoustically than it really is. This is because the absorbent material slows down the sound waves in the box which is mathematically similar to having a slightly larger box.

If you have used a computer program to work out the box volume then check if it takes into account how much absorption material you are using (some do, some don't).

If you are not using a computer program, the safest bet is to leave the box volume the same. If you increase it to allow for the foam volume you will in fact make it too big acoustically for the reason mentioned above.

Good luck..

yeah, my sub box is a little smaller (1/2 litre or so) than recommended, and the filler dampens it, so it works fine.

I tried the Jaycar stuff out in my sub box on the weekend,
it made the speaker alot quieter, and lost some of it's detail and precision,
I'm assuming it had too much of a dampening effect, by comparison to the plain chant.

No idea.. certainly was no good for the sub box like the Plain chant was.

oh well $15 wasted

Juls

Hello Juls,

For what it is worth, many years ago I used a self adhesive damping/absorbing sandwich material called Black Hole 5 in an audiophile quality pair of speakers I made for a friend and it made a fantastic difference to the clarity and the purity of the sound. It was certainly significantly better than acoustic grade foam and also than natural pure wool that we tried. None of the other treatments managed to remove a harshness in the sound caused by sound reflections and standing waves in the box. Black Hole did the trick in combination with some wool.

We got this product at the time from WAR Audio in WA and I think they may still sell it. Check their web site www.warco.com.au

Below is the data sheet for this product - I am thinking of trying it on my car doors myself.

Have you heard of it or of anyone who may have used it in a car?

You can tell the difference from 1/2 a litre?!?!

it was odd, all those books i read (no crap i read heaps) and everything everyone ever told me about them never prepared me for when i tried myself...

Where to get the Black Hole?, the site u gave us, didn't have the product listed, or should i just ask them via email??

Hello Reza,

BlackHole is made by Orca Design of the US but WAR Audio are the agents in Australia and you can buy it from them.

Best thing may be to give them a call on (08) 9242 5538. Ask for Pat O'Brien or Heath.

I am not in any way connected with them but I have dealt with them in the past when I used to design and build audiophile grade speakers as a hobby.

Best Regards

yes - whether it's the speakers, or just me - there was a difference, much tighter, less boomy