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Old 01-22-08, 01:46 AM   #1 (Link)
 
jerome
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Calibration with REW


After receiving one SVS PC-Ultra unit last week, I decided to start calibrating my system using REW. I used it previously but that's the first time I use it for sub calibration. And I want to get it seriously done this time

Currently, I only own a digital RadioShack and a laptop but I plan on buying a good mic (probably ECM8000) and a good sound card (probably E-MU 0404) very soon.
I don't have any BFD (yet), that's something I will have to decide when I get further down the road ...

My room is around 4.6m (L) x 3.55m (l) x 2.05m (H). Here is a picture to illustrate my front row:
IMG_ 012.jpg
I sit in a 3-seat sofa which is more or less one meter from the back wall. I have placed the front speakers and my sitting position using some reference music only (never used REW to optimize them).

For info: I know that I have some kind of acoustic problems (naked walls for instance). I have added two identical absorbing panels on the front and four on the back (right behind my sofa). I will start a separate thread soon to discuss acoustics and what I can do to fix the room.


I have tried many position for my sub and I get the best frequency curves when the sub is placed in the middle of the room (right or left). I don't really want to do place it there so my second best option is behind one front speaker. I arbitrary chose the left one for now. Here is my current curves (with mains):
Clipboard05.jpg

For info, this is a measurement with my front speakers only (crossover at 80Hz). The first graph is a full range measurement, the second one a zoom over the 15Hz-200Hz area:
Clipboard01.jpg
Clipboard04.jpg

The peak at around 36-38Hz is due to my room, as shown below in this table:
Clipboard08.jpg

I can't find a good reason for the 7Khz peak. Anyone ?

LF Waterfall:
Clipboard07.jpg

LF Decay time:
Clipboard06.jpg

Impulse response:
Clipboard11.jpg

I have tried to increase the sub gain and reduce the 36Hz peak using the PC-Ultra PEQ but did not succeed.


I'm relatively new to this so any advice is welcomed. I am quite happy with my 2-channel setup: Instrument location, sound stage dimensions, 3d is good and I have some work to do with treatments to improve my room acoustics.
Should I start with that before integrating my sub with REW ?
What can I do to get a better curve ?
Where does this 7KHz peak come from ?
Anything shockingly wrong ? I hope not ...

EDIT: corrected REW curves according to Bruce's recommendations. Sorry guys, I should have read the guidelines a bit better ...


Martin Logan Vista | Swans F1.1C | SVS PC-Ultra | SlimDevices Transporter | Bladelius Tyr | Yamaha RX-V1800 | Denon DVD-2930 | Klipsch RS-52 | Sharp XV-Z3000 | Adeo Greyvision Plano 16:9 100"

Last edited by jerome; 01-24-08 at 12:46 AM.

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