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



## rlammi (Jul 2, 2006)

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.


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## brucek (Apr 11, 2006)

*Re: how to make al this work (spl to rew to bfd) help*

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


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## rlammi (Jul 2, 2006)

*Re: how to make al this work (spl to rew to bfd) help*

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.


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## brucek (Apr 11, 2006)

*Re: how to make al this work (spl to rew to bfd) help*



> 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..












> thanks and I will try to import them in


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

brucek


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## rlammi (Jul 2, 2006)

*Re: how to make al this work (spl to rew to bfd) help*

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.


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## rlammi (Jul 2, 2006)

*Re: how to make al this work (spl to rew to bfd) help*

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 .


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## brucek (Apr 11, 2006)

*Re: how to make al this work (spl to rew to bfd) help*

See here


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## rlammi (Jul 2, 2006)

*Re: how to make al this work (spl to rew to bfd) help*

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


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## brucek (Apr 11, 2006)

*Re: how to make al this work (spl to rew to bfd) help*

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










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


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## rlammi (Jul 2, 2006)

*Re: how to make al this work (spl to rew to bfd) help*

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


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## brucek (Apr 11, 2006)

*Re: how to make al this work (spl to rew to bfd) help*

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.



> 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.



> 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


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## rlammi (Jul 2, 2006)

*Re: how to make al this work (spl to rew to bfd) help*

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.


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## brucek (Apr 11, 2006)

*Re: how to make al this work (spl to rew to bfd) help*



> 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.









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.










brucek


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## rlammi (Jul 2, 2006)

*Re: how to make al this work (spl to rew to bfd) help*

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 .


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## rlammi (Jul 2, 2006)

*Re: how to make al this work (spl to rew to bfd) help*

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 .


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## rlammi (Jul 2, 2006)

*Re: how to make al this work (spl to rew to bfd) help*

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


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## JohnM (Apr 11, 2006)

*Re: how to make al this work (spl to rew to bfd) help*

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.


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## rlammi (Jul 2, 2006)

*Re: how to make al this work (spl to rew to bfd) help*

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


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## brucek (Apr 11, 2006)

*Re: how to make al this work (spl to rew to bfd) help*

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


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## rlammi (Jul 2, 2006)

*Re: how to make al this work (spl to rew to bfd) help*

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.


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## rlammi (Jul 2, 2006)

*Re: how to make al this work (spl to rew to bfd) help*

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


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## brucek (Apr 11, 2006)

*Re: how to make al this work (spl to rew to bfd) help*

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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## rlammi (Jul 2, 2006)

*Re: how to make al this work (spl to rew to bfd) help*

brucek ,I am not sure what kind of sound card ,it looks generic maybe what came with the computer ,and the computer isn't anything special.And I haven't done anything for the calibrations .Were do I put those in, before I import the readings?I will readjust the axis next time I run it .I also am have a hard time understanding what the graphs mean also ? I will reread al lthe rew help text and see were I am .ON the sound card issue I have tried hooking it up to the line and the mic and the meter is reading one thing and rew is reading another .
Thanks brucek , I will rerun the readings once I figure out what calibration files I needs .


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## brucek (Apr 11, 2006)

*Re: how to make al this work (spl to rew to bfd) help*

There's really no use in posting graphs until you have all the problems with REW solved.

The first step is ensuring you have it connected correctly and that you have your soundcard type selected in REW.

Let's solve that puzzle first.

The picture below is the recommended hookup. Let's get that part out of the way before we move on.











Note the stereo adapters that plug into the soundcard. One connects to the LINE-IN and one connects to the LINE-OUT. Note we are using only the right channel on the adapters and not the left....

Is this the hookup you have exactly, including the correct adapters?

If so, the next thing you need is the soundcard information so you can select it in REW.

In Windows go to START / CONTROL PANEL
In CONTROL PANEL double click SOUNDS and AUDIO DEVICES
Select the AUDIO TAB.
The sound play back and sound recording entries will show the name of the default audio card being used. Remember this name, since you'll need to select it in REW for its playback and recording entry.

Is there anything so far that you don't get? No use moving on until that's complete.. 

bruce


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## rlammi (Jul 2, 2006)

*Re: how to make al this work (spl to rew to bfd) help*

brucek ,
I purchased those same adapters but they both won't plug in at the same time .I tried using the headphone out on the front of the computer .Then I went and got strait rca to 1/8th adapters so I could plug them both in ,still the same thing I is reading what rew is putting out ,the spl meter is reading higher .I will recheck the sound card info and let you know and I won't try anything else until I get that working ,sorry for wasting space on the forum .
Thanks again ,Ron.


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## brucek (Apr 11, 2006)

*Re: how to make al this work (spl to rew to bfd) help*



> I tried using the headphone out on the front of the computer


No, don't use anything but line-in and line-out.

Yes, the wired adapters are just as good and in fact seem to put less of a physical strain on the soundcards connectors.

Hopefully you're talking about something like this:










If so, then we have the hookup problem out of the way.

Find out about your soundcard and we can continue step by step. Each step is necessary or the results are meaningless.

You're not wasting space - if you have trouble, it means others can be in the same boat.

brucek


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## rlammi (Jul 2, 2006)

*Re: how to make al this work (spl to rew to bfd) help*

brucek, the adapters i got were one side rca female to one side 1/8 for the sound card side ,I do have the first type of adapters you showed ,but they would not fit and seeings how only half was used I went with the singles adapter end,not a y type adapter .Now for the hookup at the processor it seem to be fine although I am running and I/ B subwoofer in stereo so there are two channels going to the bfd does onlyy hooking one channel up make a difference ? I have three sub outs on the processor ? Thanks again ,I will check the sound card info and let you know .I will recheck al lthe connections .


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## brucek (Apr 11, 2006)

*Re: how to make al this work (spl to rew to bfd) help*



> but they would not fit and seeings how only half was used I went with the singles adapter end,not a y type adapter


Ah, there's our first problem. You *cannot* use a single mono 1/8" connector plug at the soundcard for line-IN and line-out because those jacks are stereo. Yes, we only want to use one channel of the two stereo channels of line-in and line-out, but that doesn't negate the fact that we need to plug a stereo plug into a stereo jack - nothing else will do - you'll have to take another trip to the store. 

That's the reason you need a Y-adapter like this:












> so there are two channels going to the bfd does only hooking one channel up make a difference ?


No, that's fine. Since an IB is co-located with itself, you won't require unique filter settings in each of the BFD's two stereo channels. You will simply use the BFD's "couple" mode so you only have to enter filters into one channel and it will copy automatically to the other.

brucek


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## rlammi (Jul 2, 2006)

*Re: how to make al this work (spl to rew to bfd) help*

Okay brucek,now I am confused the first stereo adapters were different ,will the y type adapter do the same thing?If so then I do need to go to the store again .
I do have the same stereo adapter you showed me in the very first post of them ,but they both won't fit in the in and out on the sound card so I put it in the headphone out on the front ,then went with the mono adapters .If the mono ones don't why will it still let me put tones to the subwoofer ?If the Y- adapters will work i will try them because they will fit in the back of the sound card.


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## brucek (Apr 11, 2006)

*Re: how to make al this work (spl to rew to bfd) help*



> now I am confused the first stereo adapters were different ,will the y type adapter do the same thing?


The two adapters below are identical. You need to get two of them - either kind. One for line-in. One for line-out. I shouldn't have used the term Y adapter - sorry, my bad, I was in a rush.


















They are both stereo 1/8" male plug to two RCA plug or jack.

Sometimes a mono plug works because it luckily catches the right spot internally on the stereo jack, but can cause shorts or mixing etc. Don't use mono.


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## rlammi (Jul 2, 2006)

*Re: how to make al this work (spl to rew to bfd) help*

Thanks brucek , I will be off to Radio Shack again to get the Y type adapter they will fit the sound card .So once I get them I will retry the rew and let you 
know .Thanks again it looks clearer now .


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## brucek (Apr 11, 2006)

*Re: how to make al this work (spl to rew to bfd) help*



> will retry the rew and let you know .


Ya, get the adapters - find out about your sound card and then I can continue with some tips to proceed. It won't be difficult... sometimes it's little things people miss that throw the whole thing off.

brucek


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## rlammi (Jul 2, 2006)

*Re: how to make al this work (spl to rew to bfd) help*

okay bruce will do ,I will get back to you when I get a chance to get the adapaters and rechecked the sound card ,will probably be friday ,due to work .
Thanks again Ron.


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## Otto (May 18, 2006)

*Re: how to make al this work (spl to rew to bfd) help*

Hi guys,



> The two adapters below are identical


Well, they're close to identical, but one is male and one is female on the RCA end. I'm pretty sure the shack will have the female Y adapter as well as the one pictured above (male). For my setup, I need the female (and I ain't just talkin' about my REW setup here :laugh: ) 

Not trying to be nitpicky, just trying to save you _another_ trip to the store. And I know all about making several trips to the store :run: 'cause I ended up with the upside-down version of whatever it was I went to get. :laugh:


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## rlammi (Jul 2, 2006)

*Re: how to make al this work (spl to rew to bfd) help*

Yeah otto I saw what you ment ,but I reread it a couple times and looking at the first adapters I figured it had to be female to male .I know what you ment about the trips to the store .hopefully this will be the last and I can get it up and running .


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## Guest (Jul 19, 2006)

*Re: how to make al this work (spl to rew to bfd) help*



brucek said:


> As shown here in the REW help file.
> 
> Notice the soundcard adapters are stereo..
> 
> ...


I think what's confusing here is that people (I'm one of the confused) expect a linear connection pattern showing unit to unit with specific part numbers for the connections. The current image shows connections going to nowhere.


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## brucek (Apr 11, 2006)

*Re: how to make al this work (spl to rew to bfd) help*



> The current image shows connections going to nowhere


Can you give me an example? I don't really understand. Each connection is labelled.

brucek


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## rlammi (Jul 2, 2006)

I see where everything goes ,just one question if I get response from the sub threw the rew ie: changed in tone and output when adjusted then the hookup at the processor to sub is okay ? My processor has three subouts .The rest I think I have down just need stereo jacks ,not mono.WIll post again once I get the new connectors .


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## brucek (Apr 11, 2006)

> then the hookup at the processor to sub is okay ?


yes. I would still use stereo adapters even though a mono may appear to work though.


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## rlammi (Jul 2, 2006)

okay ,brucek stereo it is ,that may have been it from the get go because the other adapters would not fit in the line in and outs I used mono connections 
so when I get the other ones I will try rew again and hopefully post corrected graphs .In one of your posts you mentions corrected calibrations for the spl meter ,were do I add them or will rew do it for me once I get it running correctly ? Thanks again .


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## brucek (Apr 11, 2006)

> were do I add them or will rew do it for me


I really think it best if you get the adapters and find out what soundcard you have and then we will go through the setup of REW step by step. It will go a lot smoother that way.

brucek


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## rlammi (Jul 2, 2006)

Okay will do,thanks again brucek.


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## Guest (Jul 19, 2006)

I just want to say that, as a fellow newbie, I'm happy to be able to read about rlammi's trials and tribulations. Not because I'm glad he's having problems, but because it helps me understand the issues before I get my feet wet.

(I'm going to be making trips to Radio Shack to get the same sorts of adaptors for my sound "card".)


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## rlammi (Jul 2, 2006)

DaveNagy 

It has been a little bit of a project getting this to work ,but hopefully one more trip and it will be ready ,I am looking forward to seeing the difference in the way my I/B sounds when I get it dialed in . I COULD take the readings manually and import them ,but that takes alot of time and then putting it into a text file .Anyways this is a learning expirience .Ron


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## surrey lad (Apr 21, 2006)

*Re: how to make al this work (spl to rew to bfd) help*



brucek said:


> You're not wasting space - if you have trouble, it means others can be in the same boat.


 you're telling me!!!


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## brucek (Apr 11, 2006)

rlammi,

As promised, I wrote up a rough step by step walkthrough of using REW to obtain a correct response graph. Hopefully you were able to obtain the correct adapters and now know what soundcard is in your computer.

You can follow through and post any questions if you have trouble. Hopefully others might begin their own threads if there are questions - we'll leave this thread to rlammi.

OK, now that the inter-connections are all understood, we need to ensure REW is configured using your soundcard for both output and input. 

At any time if you need more detail you can simply refer to the REW HELP files.

------------------------------------------------------------------

Start REW and observe down in the bottom left of the screen as shown in the attached picture. Be sure your soundcard is recognized and selected in the two pulldowns as shown. 
You can see in the example that my soundcard is a RealTek AC97.

Also select LINE_IN as shown and SPEAKER as shown.











------------------------------------------------------------------

Next we have to create a soundcard calibration file that will be saved and then automatically loaded in the future every time REW is started, so we only need to do this once. This step enables REW to compensate for inadequacies in a soundcard.

First you need to connect a cable from the right channel output to the right channel input of the soundcard. Remove any cables on the ends of the (1/8" stereo to RCA left/right adapters) and add the shorting cable as shown below.











OK, now select the Soundcard tab in REW and then Select *"Measure Soundcard Response"* from the Soundcard pull-down menu. Accept the default and continue. Results from the measurement will be shown on the Soundcard tab.

The graph results of the measurement should look something like the picture below - if the result is significantly different, stop. Read the section in the help files on Calibrating the Soundcard and solve the problem before continuing or report back to the thread:












If all is good then Select the *"Save Measurement as Soundcard Cal File"* option in the Soundcard pull-down menu and choose a name and location for the file in your computer. The file is saved and then loaded as a calibration file to use for all subsequent measurements. On the next REW startup the file will be loaded automatically with a confirmation message. No need to do this step ever again.

------------------------------------------------------------------


Now we need to load the calibration file for the specific type of Radio Shack (RS) meter you own. Once the file is loaded it will reload automatically every time you start REW in the future. 

There are three types of meters - two analog and one digital.
Go HERE and determine your type of meter and download the appropriate *.cal file to your computer. Simply right button select the file on the web page and 'save target' to a directory.
Now select the METER pull down in REW and *"load meter calibration file"* from the location where you stored it.


------------------------------------------------------------------


OK, remove the short used in the soundcard calibration and hook up the cables from the soundcard to your receiver and to the SPL meter. You should shut everything off to do this hookup. The subwoofer and receiver and BFD should then be turned on (with the mains speakers shut off or disconnected). You'll notice when you restart REW that the soundcard calibration file and the meter calibration file automatically load.

The SPL meter should be placed in the listening position and select 80dB on the dial and select the C-weight switch and Slow response. 

Be sure the BFD doesn't have any filters engaged for this step. You can turn all the filters off or you can simply bypass the filters by pressing the IN/OUT switch on the BFD so the green LED goes out. We don't want filters for the raw measurement.


Once REW is started, select the SUB tab in REW and also select the GRAPH AXIS EXTENDS icon (as shown below) and set the limits to 15Hz to 200Hz and 45dB to 105dB. This graph info is stored now and can be recalled any time by pressing the icon.












Also change the TARGET level in REW from 75dB to 80dB. You may also change the default crossover frequency from 80Hz if your system crossover is different. Your graph should look like the picture below. Turn off the graph visual of the soundcard cal and the meter cal by clicking the buttons shown. It makes for a cleaner display. The fact that they are present indicates you've loaded them properly.
The target will be the only thing left on the graph now.










------------------------------------------------------------------


Now we are ready to carry out 5 steps to complete a measurement. Mostly REW guides you through them with pop-ups. You can also refer to the HELP files for more detail. I'll just provide the overview steps. If any step fails - stop, there's a problem. Solve the problem before proceeding.


*STEP 1. SET MEASUREMENT LEVEL.* 
This sets the output level of REW and the level of your receiver so that it produces 80dB on your RS meter. The procedure is fairly well explained in the pop-ups. Press the button and adjust the volume on your receiver so that your RS SPL meter reads 80dB (use 80dB instead of 75dB as instructed because it places the meter needle in the center of the meter movement).



*STEP 2. SET INPUT VOLUME. *
This procedure sets the input volume to REW and again is explained in the pop-ups.



*STEP 3. CALIBRATE SPL METER. *
This procedure has you adjust the SPL meter in REW to match the real RS SPL meter, so they're in sync. Simply press the button and adjust the thumbwheel on the REW pop-up to match the level you read on your RS SPL meter. Hopefully it will be around 80dB, but set it to exactly what the Radio Shack meter reads. If it's 82 - good, then that's the level. The RS meter jumps around a bit, so average what you feel it's reading.



*STEP 4. SET TARGET LEVEL. *
This step is completely automatic and is used to give REW a reference in filter creating etc. It should return a result around 80dB, but allow it to set itself after pressing the button.



*STEP 5. AUTOMATIC MEASUREMENT. *
You're ready. The sweep limits should be set from 20Hz to 200Hz. Press the button and wait for the results. Once the graph appears it is wise to press the Graph Axis Limits button to reset the graph to our desired default limits.

------------------------------------------------------------------


Before you save the results be sure to set the REW pull down *Analysis* - Pre impulse response window to Tukey 0.25 and then click the pull down VIEW and select *Impulse response controls* and set the *Pre-ref window width* to 125ms and click Apply Windows. Now return to the Filter Adjustment screen. See the attachments below. This step will provide a truer graph of your results.




































You can now save this raw graph data by using the pull down FILE - *Save Measured data set*. You can then reload this graph anytime in the future to work on your filters off-line.

You can also save this graph as a jpg for posting by using the pull down Graph - *Save as jpg*. . Set the width for 800 pixels (although some laptops won't allow that high. Go as high as you can up to 800 pixels wide.

See if you get this far and then we can discuss filter setup in the BFD.


brucek


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## Guest (Jul 21, 2006)

Wow Bruce, that's brilliant. Hopefully this info will be made more widely available. To avoid sidetracking rlammi's thread, I will ask my questions elsewhere.


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## rlammi (Jul 2, 2006)

brucek
I think I see were I went wrong ,besides the adapters ,ther sound card you show in the example is the same one I have I was selecting stereo and or the aux selection in the window .I have the adapters now and will rerun everything once my daughter is done watching pear harbor .It makes a lot more sense now thanks for the run thtough of rew .


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## rlammi (Jul 2, 2006)

brucek
Here is my first attempt at the sound card calibration ,it looks okay out to 400 hz then it goes crazy I have read through the help file but it only shows for a soundblaster 24 and my graph isn't that crazy .Can I run with this reading or do I still need to tame it more ? Is volume setup in the sound card affecting it ?Thanks again brucek looking forward to getting this part dialed so I can proceed with real measurements . Thanks Ron.


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## brucek (Apr 11, 2006)

> Can I run with this reading or do I still need to tame it more


 No, this is a show stopper. It has to be corrected before carrying on. 

Are you sure that you have the right channel of both your adapters connected together - sometimes it's hard to tell left from right.....

Perhaps John M can chime in here - he may have seen this type of response in his testing?

brucek


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## rlammi (Jul 2, 2006)

I will try it again and see if I can figure the two out and get a better reading thanks brucek


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## Matteo (Jul 12, 2006)

Brucek,
Thanks so much for your time. I am just beginning to get started and was ready to pull my hair out. This thread makes it a lot easier. Maybe you should link it to the help files. You need a Nobel or something for your work. Thanks.
Roly
:hail:


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## rlammi (Jul 2, 2006)

brucek

I got my old computer working was using my daughters .I took another reading on the soundcard calibration ,does this look any better ?let me know .I found that the in and out lines on the sound card were loose so holding them in place I got the reading you see .


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## JohnM (Apr 11, 2006)

rlammi said:


> brucek
> Here is my first attempt at the sound card calibration ,it looks okay out to 400 hz then it goes crazy I have read through the help file but it only shows for a soundblaster 24 and my graph isn't that crazy .Can I run with this reading or do I still need to tame it more ? Is volume setup in the sound card affecting it ?Thanks again brucek looking forward to getting this part dialed so I can proceed with real measurements . Thanks Ron.


Huge dips in the soundcard measurement are typically caused by an internal monitoring path being active (the frequency at which the dip occurs is linked to the delay through the monitor path). Can also get strange looking results if effects processing is active (e.g. CMSS, or some sort of 3D sound effect etc).


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## JohnM (Apr 11, 2006)

rlammi said:


> .I took another reading on the soundcard calibration ,does this look any better ?let me know .I found that the in and out lines on the sound card were loose so holding them in place I got the reading you see .


That one looks fine.


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## rlammi (Jul 2, 2006)

Awesome thanks johnm and brucek will continue on and get this thing working .:jump:


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## rlammi (Jul 2, 2006)

Okay brucek and johnm now mine looks like the one in the previous post by brucek I didn't have it set down the 15hz and the up and down wasn't right now this looks like a better reading .let me know if we are good to go and I will try and take some radings later today.Thanks for being patient I think I am coming along .


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## brucek (Apr 11, 2006)

Yeah, looks like you have a proper soundcard cal file now. Hopefully you saved it and now it will load each time you start REW.

Continue on following the script I wrote and see how it goes. :T 

If any step seems wacky..stop and we'll find out why.

brucek


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## rlammi (Jul 2, 2006)

Yes brucek I save the file and will try and take some readings later today ,oce I reread what you posted and make sure everything is reading correctly . It was getting frustrating there for a bit no matter what I tried the reading was off, then I grabbed my old computer and finally it looks good so the rest of the way will be with the old computer .Thanks again ,Ron.


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## rlammi (Jul 2, 2006)

brucek and johnm ,
Finally got a little time this is the first graph I have done looks kind of bad though let me know where I went wrong,thanks Ron.


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## brucek (Apr 11, 2006)

> looks kind of bad though


Not at all. You simply have the graph axis limits incorrect and you did your sweep too wide.

Set the Automatic Measurement sweep limits from 20Hz to 200Hz and set your graph axis limits as shown in this thread and try again..

brucek


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## rlammi (Jul 2, 2006)

okay brucek , just reset every thing and took another reading how does this look?
note I am also in the middle of build a new center channel so I will check back when I take a break .
thanks for the help.Ron


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## brucek (Apr 11, 2006)

> took another reading how does this look?


No, you didn't modify your graph axis limits as I discussed in the above thread. 

Your horizontal axis must go from 15Hz to 200Hz. Then it will be fine.

Good work....Looks like you need some BFD filters... that's next. 

brucek


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## rlammi (Jul 2, 2006)

Okay brucek I see what you mean about 200 not 20,000:duh: so yeah that looks better .were wupld my first filters go ? So I can set them and then take another reading .Thanks again brucek.


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## rlammi (Jul 2, 2006)

brucek


Does this look closer to what you are looking for?


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## rlammi (Jul 2, 2006)

Sorry brucek ,like roly said shoot me if the axis isn't right next time this is what you are looking for .


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## brucek (Apr 11, 2006)

> Does this look closer to what you are looking for?


Excellent. Although you can uncheck the buttons to turn off the soundcard cal and microphone cal at this point so it doesn't clutter the graph.

Looks like you need some filters for sure. I'm surprised that the bottom end drops, but you may find that when you reduce the other area somewhat with filters and then raise the wholesale gain (assuming your subwoofer power amp has the headroom), you'll be fine.

I will copy some information here from another post on filters. Then all your information is in one post.

Below is step by step of using REW to create recommended filters and then entering them into the BFD and then re-measuring to check the results. I'm assuming that the filters will be entered into the BFD manually from its front panel. The BFD manual can be used to describe how to enter filters. It's quite easy.

So at this point, you have taken a raw measurement with no BFD filters and saved it as a *.mdat file (using the pull down FILE / Save Measured Data Set). You are able to load that mdat file at any time in the future to work on your filters, but you may as well do some filters now when everything is hooked up and enter them into the BFD so you can test how they work.

Something you have to realize about REW is that it won't automatically create any suggestions for filters for dips that require gain. It simply suggests filters that will reduce the peaks down to the target line. This is smart since it has no idea if a filter with gain will work in a system, due to the fact that some dips in response are a result of a room resonance that won't budge no matter how much gain you throw at it. 
In that case all you're accomplishing is to reduce your available headroom. So filters with gain are trial and error. If you have a dip, you can use REW manually to produce the best suggested filter with gain as if it would indeed respond. Then you enter that filter and do another response measurement and see the effect. Some dips simply respond exactly as REW predicts and some dips are very stubborn. Don't waste your time on them.

This part of the procedure requires some creativity on your part. REW will indeed automatically suggest some filters for you to enter (after pushing a few buttons) and shows on the graph the likely result after entering them. The predictions are remarkably accurate. If you just followed the advice of REW for filters you would remove all the worst peaks and your system would sound better. This just doesn't satisfy most people though. The fact is, after you have pushed the buttons to get the filters that REW recommends, you should use REW in the manual mode and play with the filters by adding your own and modifying the suggested ones until you get a smooth response predicted on the REW display. Then enter those filters into the BFD and see if the response is as REW predicts, and then tweak a bit to get it perfect.

Let me go through the procedure and show a few pictures.

Once you've taken the raw measurement and have saved that mdat file, it's time to let REW suggest filters.

I'll use my own system in the pictures. Here's my raw measurement and my target. My target is 80dB, but I have added a house curve to the target and have a crossover at 60Hz, so my display will look somewhat different than yours.











*1. FIND PEAKS *
Press this button and REW will find the peaks within the limits of the find peaks default entry of 20Hz to 200Hz. I usually set this first to 15Hz to 200Hz. Remember a BFD can only enter filters down to 20Hz, but I get better suggestions from REW with a lower limit of 15Hz.
REW will find the peaks and display them in a slightly annoying chart in the left hand side of the graph. You can see by the little chart that the frequencies are at the peaks. I suggest *every time* this chart pops up to remove it with a couple Cntrl-Shift-P's.
Here's my own systems raw measurement and the associated FIND PEAKS chart. It shows, for example that there is a 10.2dB peak at 34.5Hz.











*2. ASSIGN FILTERS *
Now press this button and REW will assign appropriate filters to attempt to remove the peaks it found. The suggested filters are displayed in the bottom right hand corner of the REW page. The green entries are the actual BFD front panel entry for the frequencies. 
Below are the suggested filters:











*3. OPTIMISE PK GAIN AND Q *

Press this button to automatically adjust the gain and Q settings of the suggested filters to obtain the best match to the shape of the peaks and so create the flattest corrected response. The corrected predicted response is now displayed along with the graph of the filters. The display graph gets very busy now.
*You can remove all the extra stuff on the graph now to get a better picture of what the predicted corrected response will be. Turn off Sub Measured, Filters and Filters+Target to reveal only the target and the SUB CORRECTED response.* At this point, if you simply entered those suggested filters, your response would look fairly close to the predicted response that REW now shows.

Below is the predicted response if I used the filters suggested:











*GET CREATIVE*

Here's where you play with the filters manually by adding your own and also modifying the suggested ones to arrive at the best and flatest response (without getting too crazy). I ended up with quite a few extra filters as you can see by the diagram below.

Bandwidths can be any size, whatever works. Gain is the trouble maker. Sometimes you need to apply two filters side by side to get a result. If you have the filters available it's better to divide a large gain or cut in two and divide it between two filters. Two at +5db is better than one at +10db at the same or close frequency. The filters with gain shouldn't be too high, but there is nothing wrong with some gain if it works. 

Note you can save your filter settings in the BFD as a req file under FILE / Save Channel Filter Settings. Then you can recall the raw mdat file and recall the filters and play with them off line.


When you modify and add filters be sure to press the *ADJUST PK GAINS* after you do so......Play around with the parameters of each filter and see what it effect is on the response - REW dynamically shows you the results.











Below is the actual response (and very close to the predicted) that I achieved by the new and improved creative filter journey.











Once you like the look of the predicted graph it's time to enter the filters into your BFD and then do another REW response check to see if the actual response is as good as the predicted response. Where it will possibly differ is in the areas where a filter has gain.

Read the next line carefully because it's quite important!

*When you do the new response sweep after the filters are entered into the BFD, you must temporarily clear the filters out of REW so they don't affect the new measurement. Just uncheck the boxes as shown below or the filters shown in REW will be applied to the new sweep measurement.*
See the picture.










If you don't like the new response you obtained with the filters that you've entered into the BFD, you can reload your raw mdat file and then uncheck the filters and play some more. It can be several iterations (or not) before you're satisfied with the response. (You can see why the midi cable would be handy at this point). I don't have one myself, but I get why it's nice to have...


-----------------------------------------------
brucek


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## rlammi (Jul 2, 2006)

Thanks brucek,
will remove the soundcard and mic from the graph ,looks like I have some work ahead of me .I am going to run rew one final time and double check everything before I start setting filters just to make sure .will keep you updated .As I stated my be a bit I am building an audax 3-way center channle and doing some stuff to keep the wife happy.thanks again brucek.I will post my testing once I have some filters set .


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## rlammi (Jul 2, 2006)

brucek,

I have had a chance to set a couple filters .will have to reread your last post for some reason I can't seem to get rew to adjust the graph as I adjust filters .obviously it is someting I am doing I will work on that .Do have one question that I haven't been able to figure out ,I have 12 filters I have set 7 ,how do I set the inbetween frequencies I.E.
filter 1=20hz +8
filter 2=25hz +5
filter 3=63hz -7
filter 4=80hz -2
filter 5=100hz -3
filter 6=125hz -3
filter 7=160hz -2

some of the cuts I guessed on I know there is a way to look at it in rew I just have to figure it out .Anyways though I would ask,and will try and rerun a sweep and see what theses filters did if anything .Thanks for your patience 
Ron .


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## brucek (Apr 11, 2006)

> I have 12 filters I have set 7 ,how do I set the inbetween frequencies


I don't understand the question. You can set any filter to any frequency you desire to a linear resolution approximation of 1/60th of an octave using the Fine button. Take another look at the BFD manual.



> some of the cuts I guessed on I know there is a way to look at it in rew I just have to figure it out


Don't quess. You're wasting your time if you do so. You have to figure out REW and enter the correct values. You'll create a worse sound for your bass by quessing. Re-read the filter post.

brucek


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## rlammi (Jul 2, 2006)

Thanks brucek,
WIll do ,I will reread all that ans recheck and reset the filters and rerun rew.The reason I asked is that it did't go from 20,21,22,23,24,or 25hz it jumped from 20 to 25 and so on .Anyway thanks I will reread those that you suggested .


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## brucek (Apr 11, 2006)

> it jumped from 20 to 25


Well yeah, but that's the course frequency. Then you add and subtract the fine from -9/60 up to 10/60, which takes you to the next 1/3 octave. See the BFD manual.

brucek


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## rlammi (Jul 2, 2006)

Thanks brucek,

I think I finally get it went int othe bfd manual and another site adn I think I under stand you need to put the bas freq I. E, 25hz and add or subtract depending on the column it is in on the chart .Thanks will adjust that tonight and rechceck .Thanks again Ron


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## Guest (Aug 8, 2006)

That's a ton of boost 25Hz and below for 4-12"s in an IB. I suggest using more and broader cut filters higher up to pull down more of the top end response, as opposed to using so much boost really low.


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## rlammi (Jul 2, 2006)

Hello Thomasw,

I thought the build and install would be the hard part .this bfd and reqw are a little tougher ,but I am finally grasping them and the readings are off I was just trying to get a feel as to how to add a filter I will reread the stuff on your projects site and the cult as well as here brucek has been a big help figuring this out ,I have files saved at work and I am trying to figure out the best route to get the lower end up closer to the target .I still need to play with the reqw so I can feel comfortable with all I am inputting into the bfd .I think I understand the amy frequency and then going fine ,but not sure what a broader filter is ,but I will figure it out .I guess once it is dialed in it will finally be done ,not, it is never done Thanks for the great site guys brucek here at the shack and Thomasw over at the cult would never have gotten into the diy end of home audio otherwise :T


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## brucek (Apr 11, 2006)

> but not sure what a broader filter is ,but I will figure it out


If that's the case you should take time now to read any sections of the BFD GUIDE and also your BFD user manual on bandwidth of filters.....

brucek


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## rlammi (Jul 2, 2006)

I am brucek ,I will have it figured out and get a graph reran to check out once i get all the filter adjustments corrected ,and I finally figured out what you ment 
about playing around wit the filters, I didn't have the corrected box checked so it wasn't showing me the changes the filters made will tweak it and let you know .Thanks again brucek .


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## Guest (Aug 9, 2006)

Broader filter= wider bandwidth filters like 120/60 if you're using a BFD. Make 'shelving' filters to pull down the higher frequencies. I know Bruce is using a similar filter for his settings. I don't remember exactly where he discusses it's operation.


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## rlammi (Jul 2, 2006)

Thomasw or brucek 

what is a shelving filter ,I have heard it before .I finally understand the wider or broader filters ,I am going to reinput the data and then play with the filters a little more and then input them into the BFD and retake the measurement and then I guess it will be tweaking from there .I will repost once I get a chance to rerun reqw and see were any more adjustments are needed .Thanks all for the input and advice .I am ready to put a DONE stamp on this thing .


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## Guest (Aug 9, 2006)

This is an example of a shelving filter










These are the filter settings used to create it...


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## rlammi (Jul 2, 2006)

Thanks Thomasw ,how do you know were to put the filters? Yours is an example is it close enough for me to use or would I need something different ? and I don't know if you have seen my first graph ,but it almost takes all 12 filters in reqw .Would adding the shelving filter cut down the number of filters I would need in the ower frequencies ? If I am reading this type of filter it will bring the lower frequencies down so there should be less filters needed .I will try and rerun it tonight and input the filters and try and take another reading and post it so everyone can see .Thanks all ,Ron.


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## brucek (Apr 11, 2006)

rlammi,

You're getting way off track here.

Without filters, your raw measurement is quite good (as shown below) and in my opinion you don't need many carefully selected filters to correct it. You don't need a shelf filter. 










Simply do a raw measurement without any filters in the BFD and REW and then follow step by step the procedure I outlined for you.

In fact you can simply attach your measurement.mdat file and I'll suggest some filters for you to try. It's always better though if you do it and learn yourself....

brucek


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## rlammi (Jul 2, 2006)

okay brucek, I will run one more raw graph and then go threw the filter setup that you outlined and go from there. One final question can I use the first raw reading to get the filter readings or should I run another ?Thanks bruce will get the reading the the next day or so .Again many thanks I am finally understanding the process much better now .Ron


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## Guest (Aug 9, 2006)

> in my opinion you don't need many carefully selected filters to correct it. You don't need a shelf filter.


I'm certainly not suggesting he needs to copy the filter I posted. It's just an example of how they're made.

Unlike a standard 'portable' sub, IB subs don't naturally roll-off from the acoustic filter created by 'box'. So.....

Using his filter choices; 20hz +8, and 25hz +5, any music or sound effects with significantly low bass will cause the drivers to slam into the formers.


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## brucek (Apr 11, 2006)

> can I use the first raw reading to get the filter readings or should I run another


If you saved it in a xxx.mdat file, then simply use it again to create your filters off-line with REW - no need to take another reading.

Then once you enter your filters into the BFD, take a new raw reading (be sure any filters in REW are shut off) and check the results of your work...

brucek


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## brucek (Apr 11, 2006)

> I'm certainly not suggesting he needs to copy the filter I posted. It's just an example of how they're made.
> 
> Unlike a standard 'portable' sub, IB subs don't naturally roll-off from the acoustic filter created by 'box'. So.....
> 
> Using his filter choices; 20hz +8, and 25hz +5, any music or sound effects with significantly low bass will cause the drivers to slam into the formers.


Yep, and I completely agree.......


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## rlammi (Jul 2, 2006)

Thanks bruecek and thomasw 

I will rerun all the filters and take another reading and repost .Thanks for all the patience .


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## rlammi (Jul 2, 2006)

First off I would like to say thanks t o everyone involved with this brucek,johnm, sonnie and the shack and to thomasw at the cult (for getting me into the I/B project).:hail: This has really been a learing expierence with the BFD REQW and the building of this subwoofer .One forum led to another forum and there are a great bunch of people on both .I have gotten a lot of help with the filter I was trying onmy own but I wasn't really getting it I kind of do now .So here is my latest graph and it looks pretty good I thought I would need most of the filters to get it to come close to the target sor here it is and I have to thank Thomasw over at the Cult for the settings here it is and I am going to work on another setting of my own to see how I can adjust it for music I need a little more punch .Played the Eagles and some other stuff sounded great but would like a little more punch or I may need to get use to it .As for movies went right to WOTW and sounds awesome .So per the wifes request we are watching KONG tonight .here is the graph again THANKS TO EVERYONE , Ron.


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