Acoustics Forum

by **Suntower** » Sun Oct 22, 2006 11:43 pm

I got a new beta from Matthias @ RME and it -does- work with my RME HDSP9652. Yeaaaa!

I run ETF5 with my little Behringer pencil mic and I follow the initial tutorial.

---Now--- what?

1. I just ran the standard tests for full freq and low freq.

2. I don't have a mic calibration file.

3. I simply placed the mic where my ears would be @ the mix position facing the front of the room.

The horror I see are two MASSIVE peaks: 1 at 56hz and the other @ prox 110hz. OK, ----now--- what? I'm disturbed because I put a lot of time/effort into corner traps and clearly I missed something, even though the room sounds a lot better (to -me- anyway) than it did before.

Armed with this new knowledge, how should I proceed? Should I run more specific tests?

TIA.

---JC

by **knightfly** » Mon Oct 23, 2006 12:01 am

Sounds like first and second harmonics of an axial mode; what're your room dimensions (and why'd you start a new thread? :? ) Steve

by **Suntower** » Mon Oct 23, 2006 1:42 am

1. 15' 2" long x 11' 3"' wide

2. Why -not- a new thread?

---JC

knightfly wrote:Sounds like first and second harmonics of an axial mode; what're your room dimensions (and why'd you start a new thread? :? ) Steve

by **Scott R. Foster** » Mon Oct 23, 2006 2:21 am

try some sidewall panels

by **Suntower** » Mon Oct 23, 2006 3:29 am

1. Interesting! Why did you immediately suggest this?

2. But it's a great guess:
a. The left wall is a large triple pane glass window. Anything to be done without obscuring the view?

b. The right side wall is a closet with the doors taken off. I -can- put a big 'porta-trap' there to square off the room, but I doubt it will trap bass down to very low freq (it's basically just 6" of 703 ). Any way to make a movable trap like that trap deeper freqs?

TIA,

---JC

Scott R. Foster wrote:try some sidewall panels

by **Scott R. Foster** » Mon Oct 23, 2006 5:50 am

twas an inspired guess...

fiddle around a bit with thing

http://forum.studiotips.com/large_files ... ulator.zip

by **Suntower** » Mon Oct 23, 2006 4:30 pm

OK... Well I've taken a 3 minute look @ the spreadsheet and when I plug in the dimensions for my room, sure enough the modes line up with the problem freqs almost exactly (56, 110).

So... now that I've determined that 'science rules!', what do I do to combat this nemesis?

TIA,

---JC

Scott R. Foster wrote:twas an inspired guess...

fiddle around a bit with thing

http://forum.studiotips.com/large_files ... ulator.zip

by **Scott R. Foster** » Mon Oct 23, 2006 6:25 pm

More science!

And beer too!

http://forum.studiotips.com/viewtopic.php?t=47

PS: got pics?

by **Suntower** » Mon Oct 23, 2006 9:42 pm

And beer too. But not just any beer, of course.

1. I did read the topic, thanks. But unless I'm more drugged than usual, that article refers to broadband and mid/hi absorption.

My primary problem appears in that dreaded range where the 1st octave of the almighty bass geetar lives.

2. Piccies? Have we got piccies?

Ceiling: http://www.suntowermusic.com/absorber-ceiling.jpg
Left back corner, showing window running along side of room. http://www.suntowermusic.com/absorber-rearcorner.jpg
Back wall (...er... before 'new improved' absorbers) http://www.suntowermusic.com/nsback.jpg
Right wall(..again... before 'new improved' absorbers) http://www.suntowermusic.com/shwf001.jpg

I have several of the 'portatraps' shown in the rear view which I use to block the right wall (and freak out the cat) during recording. Additionally, there are corner traps from floor to ceiling in all corners.

Your thoughts, sir?

THANKS!

---JC

Scott R. Foster wrote:More science!

And beer too!

http://forum.studiotips.com/viewtopic.php?t=47

PS: got pics?

by **Scott R. Foster** » Tue Oct 24, 2006 4:38 am

The corner traps seem thin... how thick are they?

Also I would strive for an "across the diagonal" corner mount.

That cat has devil eyes!

by **Bob** » Tue Oct 24, 2006 4:47 am

I thought the cat was the 'portatrap'. :oops:

by **Scott R. Foster** » Tue Oct 24, 2006 4:52 am

maybe its a portacat?

by **Suntower** » Tue Oct 24, 2006 7:34 am

Scott R. Foster wrote:The corner traps seem thin... how thick are they?

Also I would strive for an "across the diagonal" corner mount.

That cat has devil eyes!

6".

The cat's a HELLSPAWN!

I try to keep them @ 45 degrees in the corner. (The traps. The cat goes -wherever-.)

I've seen several articles that tout putting Sheetblok on the back of such corner traps. A good idea, in your opinion? They're kinda pricey.

---JC

by **Bob** » Tue Oct 24, 2006 7:46 am

Suntower:

I've seen several articles that tout putting Sheetblok on the back of such corner traps.

I recall Philip Newell used something like a
room { 2" 703, deadsheet, 2" 703 } wall
sandwich for one of his absorbers. The deadsheet is extremely similar to sheetblock.
This was not a corner trap, just a rear wall trap.

With that design, I'd interpret the outer 2" to be an HF absorber, and the deadsheet should be a LF membrane trap.
The definition/frequencies/AbsorptionCoefficients of LF in this I'm a little fuzzy on.

EDIT:

by **Zaphod** » Tue Oct 24, 2006 8:25 am

Hey, may i see some of your graphs?

I love graphs! (and cats, too

)

Also, what experts say about ceiling/side walls angled panels?
(not too angled, since the windows is there)

by **Scott R. Foster** » Tue Oct 24, 2006 4:08 pm

Is the overall frame 6" thick or is the mineral fiber layer 6" thick?

Maybe you could turn that shelf into a large tap by filling it with slabs of mineral fiber?

by **Suntower** » Tue Oct 24, 2006 4:36 pm

I hate graphs! (and cats, too!) :mrgreen:

I only have the EFT Demo (sorry, too cheap), which graphs would you like to see?

I guess I can copy them to the clipboard and save them to a JPG.

---JC

Zaphod wrote:Hey, may i see some of your graphs?

I love graphs! (and cats, too )

Also, what experts say about ceiling/side walls angled panels?
(not too angled, since the windows is there)

by **Zaphod** » Tue Oct 24, 2006 4:49 pm

Well, we could start with the frequency plot that shows the
two peaks :D

And yep, copying to the clipboard works

by **Bob** » Tue Oct 24, 2006 11:15 pm

All the ETF (demo version) charts on this page were done by using ScreenPrint to the clipboad, and saving them with Paint.
http://www.bobgolds.com/CornerTrap/20040627/home.htm

by **Suntower** » Wed Oct 25, 2006 4:28 am

So I load ETF tonight and it crashes, telling me that I need to examine the 'Capabilities' function. So.... there will be no graphs until I can figure -that- out.

GRRRRRRRRRRRRRRRRRRRRRRRRRRRRRRRRRRRRRRRRRRRRRRRRRRRRRRRRRRRRRRRRRR

I hate software.

HATE
HATE
HATE
HATE
HATE
HATE

---JC

Zaphod wrote:Well, we could start with the frequency plot that shows the
two peaks :D

And yep, copying to the clipboard works

Acoustics Forum

ETF5 ---- OK, I got it to work. Now what?

ETF5 ---- OK, I got it to work. Now what?

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