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then_dude 21st September 2005 11:23 PM

coral flat 8 fullrange
hello everbody,

i have made an BR enclosure for my coral flat 8;
here is the link

the problem is that the speaker doesn't sound good.
the enclosure is build by the book. i used the bubble wrapper damping material. i didn't used the deflector rubber.

but still the speaker shouts. i don't have any kind of measuring system, but there must be a hugh bump in the frequency response.

the thing i do to make it sound better is trying to lift the frequency response by adjusting bass and treble.

what i do is cranck up the treble so that the highs become more audible and put on the loudness with a drawback of the bass :so that it doesn't sound honky.

still i don't think this is the sound what a diy-guy is looking for.
the speaker is capable of high treble sound and bass (you can always want more: so that isn't really the problem, but the mids: somthing where a coral single drive should be at his best is very lousy i think.

anyone with some great advise ? damping ? filter ?
if this thing ain't working fast, i'm gonna kick it out cause and start building a very hifi monitor. anyway, it would be fine is somebody helps me out on this one,

i'll take a picture if my digital cam works again


DonJuan 22nd September 2005 04:29 AM


how many hours hv you put in?

let it run at least 100 hours. they take quite a long time to run in.

please don't do anything yet.

the flat 6s are a different animal. 20 hours later, and they don't shout. but the flat 8s... at least 200 hours!


then_dude 22nd September 2005 11:38 AM

aaa, okeee

but euuu, they aren't new, i have driven them in an open baffle, and they were not new when i bought them.

or is that not important ? i mean does a driver still adapt to the load behind it , even it is not new ? and can this make such a difference .

well i'll let it run for a few weeks then.
hopefully it gets right,

thanx a lot already

DonJuan 22nd September 2005 03:22 PM


some coral models i hv are quite sensitive to this. if i don't play for days, i need to run at least half an hour before they sound good.

but do not under-estimate run in. we all know it's a bitch but you just got to do it.

bubble wrap alone is not enough. use some carpet felt.


then_dude 22nd September 2005 07:48 PM

aha i have to use some carpet felt.
okee, that's something i'm gonna try.

they do sound a little bit better already, but that can be also that my ears are getting adapted. there is something in the sound which i like, probably the mono-radiator, i mean not as much phase difference.

you say : carpet felt: what kind ? 0.5cm, 1cm, somthing like a doormat ?
and where ? behind the driver or everywhere ?

do you use other techniqes, like painting the surface, removing the wizzer, uses of a difractor in front ?

i donno, if this makes sense ?

thanx a lot already donjuan

DonJuan 23rd September 2005 04:33 AM


i get my carpet felt material from an auto shop where they do car cushion installations etc. this material is also found in my car booth (or trunk as you call it in big u s of a). it's about half an inch thick.

the super 12 forum guys recommended placing it couple of inches behind the driver. they are spot on. i typically place them up half a ft below the driver. i hang them from the top baffle so that it sits halfway between front and rear baffle.

at this point in time, please don't do any tweaks! i hv listened to corals for a long time and unlike lowthers or fostex, i don't think they require any tweakings at all. if you hv itchy fingers, only do those reversible ones. as they are out of production, don't do something you'll regret later.

some folks like a little tweeter to come in say above 16khz but this is up to you.

my advice to you is simple. let it run another 100+ hours before critical listening. stay outdoors or camp outside for days if necessary! then come back and listen.

if you still don't like the sound, i'll put you out of your misery by taking the god damn drivers from you! and best of all, you don't have to pay me! :D


then_dude 23rd September 2005 05:43 PM

aha, thanx very usefull information, thank you very much. :angel:

the coral driver is indeed getting better, the spatialness is very good. the driver has already very fine things to itself.
not everything is good. bass-bariton and double bass and especially cello sounds extreme good.
high male voice and violin isn't good at this moment, trompets are again very "reality" sounding.

i'm gonna do exactly what you are saying, gonna start seeking what exactly this carpet felt is. I have made the BR of 80cm high, but braced the hell out of it, so i'm gonna have to take 3 small pieces which i will hang in the middle, just like you told me.

i'm very impressed with the sound, so maybe i'm gonna build an fostex for my brother, probably a fe206e.

for the tweeter: maybe, i like a lot the highs, but i'm gonna see what happens, we'll see.

thanx a lot already
greetings filip

BTW 24th September 2005 01:48 PM

You might to try thin blanket as well. I've used thin blanket for the Flat and Beta 8 BR boxes and they work very well too..

then_dude 25th September 2005 08:38 PM

hello guys, what do you mean by carpet felt or thin blanket ?

i have searced carpet felt,

i have found a few types of it.

is it underfelt ? or is it really the carpet that is on top of the underfelt ?

i have found an url where there is a picture of it :

is there any other commercial product good ? it's maybe easier that way. but probably more expensive, and maybe not as good as the carpet felt.

thanx a lot anyway. i'll keep on looking.

BTW 26th September 2005 12:33 AM

Use what you can get your hands on.. The sound-proofing material from the link looks OK to me , give it a shot and see how it sounds like.

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