How to make all this work (SPL to REW to BFD) help

**rlammi** · **07-08-06, 05:14 PM**

Hello everyone ,

Have gotten spl readings from 10hz to 162hz is there a way to put them into a file and import them in to rew , I know I will eventually have to take new readings as I adjust the bfd ,but this is all a little confusing for me any help is greatly aappreciated .Thanks in advance ,Ron.

**brucek** · **07-08-06, 05:49 PM**

Yes, select FILE and Import Measured data. The measured data must be in the form of frequency and then a space and then the SPL reading and be labelled with a .txt extension.

i.e

10 90
12.5 95

You must enter the correct cal file into REW for the type of SPL meter you're using. There are three types and all three files are stored on the site.

Be sure to use the graph setup recommended here

Why not simply use REW to take the measurements? I know you have a computer.

brucek

edit: oh ya, there's a bug. You must enter the first entry as a dummy. So if your first real entry is 10 90, then before that enter 8 90 as the dummy. How's that for confusing...

i.e.

8 90
10 90
12.5 90

etc

**rlammi** · **07-09-06, 09:48 AM**

brucek ,

How do you hook the spl meter up to the computer? I wil try later today. I did a manual graph and there are some big dips not sure what they mean ,but will keep trucking along until I get this sub dialed in. thanks and I will try to import them in.

**brucek** · **07-09-06, 11:48 AM**

Quote:

How do you hook the spl meter up to the computer?

As shown here in the REW help file.

Notice the soundcard adapters are stereo..

Quote:

thanks and I will try to import them in

I assume you took your readings with C-weighting turned on?

brucek

**rlammi** · **07-09-06, 02:02 PM**

Brucek

Thanks I will get some adapters and try it both ways to se how close I was and yes I had the c weighting on ,thanks again.

**rlammi** · **07-11-06, 11:30 AM**

Hello every one.
I have take readings ,just a trial here until I get some adapters to run rew through the computer to take the next set of readings ,how do i up lad an image of the first graph ? Thanks for all the help .

**brucek** · **07-11-06, 11:40 AM**

See here

**rlammi** · **07-11-06, 01:22 PM**

Hey brucek , thanks I finally just put them on the hosting service I have all the other pictures on ,the graph looks ugly so I may have done something wrong I will retake all the measurements with rew when i get the adapters so let me know what I need to fix or do with this graph. Thanks again. Ron
http://http://community.webshots.com/user/rlammi100

**brucek** · **07-11-06, 01:56 PM**

OK, here's your graph. Your link is bad, but I deciphered it....

There are some issues here.

The horizontal axis must be from 15Hz to 200Hz since we are only interested in subwoofer response. It will then increase the resolution of the area of interest.

You are taking measurements at too high a level. Try and average around 80dBSPL as shown in the target..

Did you compensate for the inaccuracy of the RS SPL meter with the correct calibration files here loaded into REW?

I doubt the spikes are realistic. There's a problem with the measurements there I suspect.

Post your graphs if possible using the link I provided in my previous post so everyone can see them.

brucek

**rlammi** · **07-11-06, 02:51 PM**

brucek , the previous link is closed .I will try the link again, I tried to set every thing at 70db ,but I guess I had it set to high .Is it easier to control through
REW or will it still take some work? I thought it loked funny ,I did it manually on graph paper and the peaks didn't look anything like what came up in rew so maybe in the transfer of the data I did something wrong ?Anyway here is the link again ,I tried the previous link but it shows it is closed .http://community.webshots.com/user/rlammi100

**brucek** · **07-11-06, 03:00 PM**

Yeah, that link works. It's just that everyone likes to see pictures because it's so easy to comment on. Try and see if you can figure out how to make an attachmenet here at the site for the future.

Quote:

Is it easier to control through REW or will it still take some work?

It's quite easy to control through REW once you have it all hooked up with the correct cables and adapters.

Quote:

I did it manually on graph paper and the peaks didn't look anything like what came up in rew

Post your text results and show us what you have. (What model of the three SPL meters do you use?)

brucek

**rlammi** · **07-11-06, 06:00 PM**

I have the new digital meter and that is what I used ,but I didn't convert anything before I imported it into ,should I have ? The graph I did was on graph
paper done manually with a pen and a ruler .I can add the number file if that is what you mean ,Don't worry as soon as I get a change to play with this a little I will get the hang of it .Thanks again brucek.

**brucek** · **07-11-06, 07:00 PM**

Quote:

I have the new digital meter and that is what I used ,but I didn't convert anything before I imported it into ,should I have ?

No, you did good. Except you copied down a few of the values wrong at 487Hz and 117Hz (as shown in the insert for 487Hz below). I corrected these and have posted the graph. I had to use REW to manually subtract a wholesale 15db from all your values to get a look at what it would be like near the target.

I can't believe how much you're outputting at those low frequencies. Amazing, must be shaking the house. You need a BFD.

I think the graphing will be much more accurate when you get REW going. It's a good start though to get yourself educated on this stuff.

graph.jpg

This shows one of the two errors in your text data causing the spikes.See the double entry of 48Hz. I corrected it and the one at 117Hz.

error.jpg

brucek

**rlammi** · **07-11-06, 07:51 PM**

Thanks brucek,figures I would have doubles up numbers ,I inputted those about three times .Yes the wife thinks it is a little loud at times but you never know when you need the power or the ability to go low .Thanks for looking over my readings .I will try and get all the adapters I need so I can get some figures some time this weekend ,trying to go camping for a few days so it may not be until the first of next week .I already have the bfd hooked up and ready once I figure out were I need to cut or add boost .The corrected graph looks better now I know why the paper graph looked better .Thanks again brucek will be back once I get rew hooked up to the bfd .

**rlammi** · **07-14-06, 02:49 PM**

Hello everyone trying to get rew going have all the cables set ,but don't know what to do to test the system and record a graph.I have been reading the help files but I am lost please help .Thanks in advance .

**rlammi** · **07-14-06, 04:06 PM**

okay I took a few readings with the spl meter and rew ,these may or may not be right I took them with the different sine wave,pink ,and other tests any advice .Thanks Ron

**JohnM** · **07-14-06, 04:38 PM**

Looks like you are measuring either with a loopback connected (i.e. you have the output linked directly to the input and are measuring that) or you have the input set as "What U Hear" or similar, which also simply records what is being played out.

**rlammi** · **07-14-06, 07:37 PM**

I hooked eveything up like brucek's photo showed ,but I will double check and repost the results .Thanks Ron.

**brucek** · **07-14-06, 07:52 PM**

The suggestion by John is that if the error isn't caused by an external mechanical loopback, then you must have the soundcard in software loopback mode.

This is evidenced by the fact that the graph is showing an exact mirror of the SPL meters calibration file. If I shorted the output of the soundcard to the input, this is what I would see. You're not reading the SPL meter at all.

Check that the soundcard doesn't have a setting that puts it in a monitor mode. What kind of soundcard do you have?

Also a minor point, but normally we use a vertical graph axis of 45dB to 105dB and a horizontal axis from 15Hz to 200Hz. Use the graph axis icon for this setup.

brucek

**rlammi** · **07-15-06, 11:17 AM**

That makes sense ,if rew is just copying down what it puts out ,with the way I had it hooked up I could hear all the sound from the subwoofer ,so it has to be with the sound card ,I don't know what kind it is just has a line in and out to the speaker or mic .I will try again and see what happens ,I thought those graphs looked to clean ,and at a funny angle ,Thanks all will report when I have a chance to rerun them
Ron.

**rlammi** · **07-17-06, 03:19 PM**

It may be the sound card I have that isn't letting me use rew to take the reading.have been working on the rew with the imported data ,and here is what have first one is with the filtes applied ,then without c-weight comp when the data was imported and then with the c-weight com any help would be appreciated ,thanks Ron

**brucek** · **07-17-06, 05:52 PM**

Do you have the proper RS meter calibration file loaded?

Have you done a soundcard calibration and saved the file?

I'm having a bit of trouble understanding what you're doing in your graphs. Set the axis limits of all graphs with a vertical axis of 45dB to 105dB and a horizontal axis from 15Hz to 200Hz.

I would concentrate on getting REW to work properly and leave the manual measurements. You'll get much more accurate results.

What type of soundcard do you have?

brucek

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