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

[brucek]

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

[rlammi]

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 .

[brucek]

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

[rlammi]

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.

[brucek]

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.

[rlammi]

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 .

[brucek]

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

[rlammi]

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.

[Otto]

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 )

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 'cause I ended up with the upside-down version of whatever it was I went to get.

[rlammi]

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 .

[JeffD2.]

brucek wrote:

As shown here in the REW help file.

Notice the soundcard adapters are stereo..





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

brucek

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.

[brucek]

The current image shows connections going to nowhere

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

brucek

[rlammi]

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 .

[brucek]

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.

[rlammi]

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 .

[brucek]

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

[rlammi]

Okay will do,thanks again brucek.

[DaveNagy]

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".)

[rlammi]

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

[surrey lad]

brucek wrote:

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

you're telling me!!!

[brucek]

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.

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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.


Soundcard.jpg


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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.

soundcardcal.jpg



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.

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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.


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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.

graph1.jpg


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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.

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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 fo