First attempt at DIY 703 panels + REW results

**CZ Eddie** · **07-05-09, 06:08 PM**

I spent the day placing ten 2x4 panels of DIY 703 rigid fiberglass panels on my walls. I didn't have any panels for the ceiling. Overall, I'm happy with the results. There was a noticeable difference and I'm pretty glad I did what I did. Highs are audibly crisper. Mids are easier to handle. And bass is more present. This appears to have fixed some major sonic problems.

But I'm concerned about the quick fall in response above 10khz? I got a similar 10khz dropoff with a different set of front main speakers also.

Here are the front speakers by theirselves with no acoustic panels or EQ.

Here is the end result - front speakers + subwoofers + Audyssey EQ + DIY acoustic panels.

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#1 These are the front speakers by themselves, no sub or EQ or acoustic panels. Just a baseline.

#2 First two pads, ones behind speakers made 110hz valley deeper.

#3 Added corner bass trap and it moved the 110hz valley to 117hz and brought the 120-130hz down a bit.

#4 Added bass trap above front door and it fixed 117hz dip a bit, made 115hz dip more pronounced. Made a new 70hz dip.

#5 Added 2 panels to right side wall which made 115hz worse, made new dip at 125hz, made top end look better though.

#6 Added 2 panels to left side wall which removed the 125hz dip but added new bad 117hz dip.

#7 Added bass trap to middle rear of room corner above computer and it made 80hz dip more pronounced but fixed 117hz dip a bit.

#8 Added two 15" subwoofers in 16hz tuned enclosures. No other changes made.

#9 EQ'd system using Audyssey MultEQ on Onkyo TX-SR805 a/v receiver.

**bpape** · **07-05-09, 06:17 PM**

OK. Well, the drop off happend on 2 different sets of speakers and also with and without panels. That tells me it's likely the mic you're using.

Bryan

**CZ Eddie** · **07-05-09, 06:19 PM**

Thanks for the quick reply. It's a Radio Shack digital meter. I'm using the Radio Shack Correction Values 2055.cal. Unfortunately, I don't have any other meters to compare with.

**bpape** · **07-05-09, 06:23 PM**

That's fine - just ignore everything above about 3khz as the mic calibration is pretty bad up high. I believe there is a .cal file for the meter on the REW page.

Bryan

**brucek** · **07-05-09, 06:38 PM**

Quote:

I believe there is a .cal file for the meter on the REW page.

Yes, there are cal files for all the RS meters on the download page, but they only go to 1000Hz. The accuracy above that is questionable, and certainly 3KHz is the upper limit for using a RS meter.

brucek

**CZ Eddie** · **07-05-09, 07:17 PM**

As I mentioned in the post above, I'm already using a calibration file. Are you guys talking about something else?

I dug out some old Sony speakers and measured them. The radio shack meter had them at about 10db higher at 11k hz than my other speakers. So I'm going to mess around with the L-pad on my new speakers and find a good place for it. I had it where it was, because it provided the flattest reponse below 10khz. So by raising it, I get better response above 10khz, but I also get a peak from 5khz to 8khz that will need to be tamed by EQ.

**bpape** · **07-05-09, 07:26 PM**

Seriously, don't worry about anything you see above 3kHz. The mic is very poor up high and you're getting a bad reading - nothing you're going to do about it.

Set your LPad for smoothest response to your ear - forget the graph up high.

Bryan

**CZ Eddie** · **07-05-09, 07:32 PM**

Noooo.... the graphs make everything so much easier!

Well it's a bummer to read that. I thought I was being smart & technical and all.

**bpape** · **07-05-09, 07:35 PM**

The graphs and the meter are fine for the bass and for relative measurements from one setup to another but should not be taken for gospel full range or for exact responses.

If you really want to use it, you just need to get a good mic and a .cal file for it.

Bryan

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