Questions Before I Try

**echomalinois** · **03-09-07, 02:33 PM**

Thinking about giving REW a try, but need some questions answered. If I understand this correctly, my sound card should have an out and an in correct? I have a cable from RS to go from my sound card to receiver. Can I run the test tones this way? Before I ask too many questions, when I down load REW, will it have clear instructions on how to setup your sound card and RS meter? I am sure that all this has been asked before but after 12 pages I am still lost. Thanks folks!

**brucek** · **03-09-07, 02:53 PM**

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Can I run the test tones this way?

Yes. The line-out of the soundcard will be from a stereo jack. You need an adapter like the one shown below to break out the stereo jack into two cables so you can connect to one of them and feed it to your receivers AUX or CD RCA connector input. (Some people put a splitter at the receivers input so they can get both mains on when the time comes).

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when I down load REW, will it have clear instructions on how to setup your sound card and RS meter?

Well, you can read the REW Help Files. It takes a bit of reading.

You connect the Radio Shack meter using the same type adapter shown above except it feed the soundcards line-in.

You also need to one-time calibrate the soundcard, which creates a file to compensate for the cards poor frequency response. And you need to download and point to a Radio Shack meter file to compensate for the poor resposne of the meter.

What are you confused about?

brucek

**echomalinois** · **03-09-07, 03:15 PM**

Not so much confused just needed clarification on what was needed to get started. Do I need a special cable to calibrate the sound card? Or is this done through the RS meter? Can you explain what you would need the splitter for? I assume that you would hook the cable in to the receiver and get stereo sound. When I get home I will start reading through the help files, may be it will give me a better idea of what is involved. Figure that I will start with REW and if need be move to a BFD. Just not sure if I want to go this far with my system. Also not sure that I am capable. Thanks Brucek!

**brucek** · **03-09-07, 03:49 PM**

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Do I need a special cable to calibrate the sound card?

Once you've plugged in your two adapter I showed above, you will have the left and right channels of the line-in and line-out available. Connect the right channel line-out to the right channel line-in. Whatever cable does that for you is the one to use.....

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Can you explain what you would need the splitter for?

You don't really. If you connect the right channel of the sound card to the right AUX in of your reciever and put the receiver in stereo, the sub and right channel main speaker would work. The splitter would make the left and right main speaker work when you need it. Generally equalization on a sub is done with the mains disconnected though. you only add the mains after the sub is equalized to check the crossover area of the response.

brucek

**echomalinois** · **03-09-07, 06:30 PM**

Just got a chance to look at the help page, boy there is a lot of info there. I will get to reading and report back if I have any questions. Thanks again brucek!

**echomalinois** · **03-09-07, 09:26 PM**

So I am back. I have a problem, I think. I keep getting the clipping notice when I try to run a sweep. I turn the levels down and check levels and it says that it is fine, then with out changing the levels I run the check again and it says levels high. There is an inconsistency some where. Any thoughts?

**echomalinois** · **03-09-07, 10:06 PM**

So I figured out the clipping thing. Just need to play around some more, things still seem a little off. thanks!

**brucek** · **03-09-07, 10:20 PM**

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I keep getting the clipping notice when I try to run a sweep. I turn the levels down and check levels and it says that it is fine, then with out changing the levels I run the check again and it says levels high. There is an inconsistency some where. Any thoughts?

That's because the Check Levels routine in the Measurement screen and the Check Levels routine in the Settings screen use different values to generate the pink noise.

The Check Levels routine in the the settings screen uses the fact that you have the 'check/set levels with subwoofer' pull-down selected.
REW double checks and verifies that the end sweep frequency that you have set in the Measurement panel matches that subwoofer setting, by the fact that its' Check Level uses the end frequency as the pink noise hi-limit cutoff.

So if you had 20KHz as the end frequency to measure for your sweep, you can see how the pink noise would be different (between the two Check Levels) and as such the low level signal you're experiencing.

Set the End Frequency in the Measurement panel to 200Hz..................

brucek

**echomalinois** · **03-10-07, 04:07 PM**

Some of the problems I was having is that I did not do the sound card calibration correct. Now I have that worked out I have another question. Are there files available for calibrating the SPL meter? If so where do I find them. I did some runs yesterday and did follow the calibrate SPL instructions, but it did not seem to work. Thanks!

**brucek** · **03-10-07, 06:54 PM**

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Are there files available for calibrating the SPL meter? If so where do I find them

BFW FORUMS Downloads.

Pick the right xxxx.cal file for your meter............... save it and load into REW.

See the REW HELP files on how to load into REW.....

brucek

**echomalinois** · **03-10-07, 11:14 PM**

brucek, first I just want to thank you for being so helpful. It is much appreciate! Sorry, but I have another question. When I run a sweep there are a few things that keep happening. First, I set my levels at 75db but when I run the sweep it tells me that I am to low. What is that all about? The only thing that is reading 75db is I think 100hz and no matter how much louder I turn up the receiver that point goes no higher but the rest of the graph seems to increase in dbs. I was thinking about not running to the receiver, just direct in to the sub. Is this possible? Again thanks! Maybe by the time I hit 10 posts, I will be able to post a chart

But I have to admit, I am ready to

**brucek** · **03-11-07, 08:00 AM**

Quote:

when I run the sweep it tells me that I am to low. What is that all about?

That's because the Check Levels routine in the Measurement screen and the Check Levels routine in the Settings screen use different values to generate the pink noise.

The Check Levels routine in the the settings screen uses the fact that you have the 'Check/Set levels with Subwoofer' pull-down selected. To double check and verify that the end sweep frequency that you have selected in the Measurement panel matches that subwoofer setting, its' Check Level routine uses the end frequency as the pink noise hi-limit cutoff. So if you had 20KHz as the end frequency to measure for your sweep, you can see how the pink noise would be different (between the two Check Levels) and as such the low level signal you're experiencing.

Set the End Frequency in the Measurement panel to 200Hz..................

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I was thinking about not running to the receiver, just direct in to the sub. Is this possible?

Then you don't have as easy a control over the 75dB target level, and you lose the crossover for your sub.

brucek

**echomalinois** · **03-11-07, 11:31 PM**

So I have been playing with this again today with mixed success. Here is a graph that shows the problem that I am having http://i5.photobucket.com/albums/y167/marcmc/graph1.jpg. As you can see 60hz is off the chart. I realized that I never unhooked my main speakers, and thought that might be where my problem was. this chart was with the receiver at max and the sound card at max output. It seemed really loud, but according to the graph I am still real low. Does this seem right? I just wanted ya to see what I keep getting. Is it possible that my room response could be causing this?

**vfrjim** · **03-12-07, 09:25 AM**

looks like the 60hz hum of electricity is playing havoc with you. You need to eliminate that to get an accurate reading. Lots of reading to eliminate hum, do a search for "Jensen transformer" and this should get you started if you cannot remove it on your own.

**brucek** · **03-12-07, 09:28 AM**

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this chart was with the receiver at max and the sound card at max output. It seemed really loud, but according to the graph I am still real low.

I don't understand why everything was at max.

Did you press the Check Levels button in the Settings routine?

Did you set the input/output levels in the Check Levels routine properly? Output level of the sweep to -12dB (with Wave volume at 1.000 and Output Volume between 0.5000 and 1.000) and and then set the level with your receiver at your Radio Shack meter to 75dB and then set the Input Volume level of REW to match output volume on the VU meter.

Then press the REW Calibrate SPL meter button to match that 75dB?

Then press the REW Set Target Level button? (I admit this button shoud look more like a button).

When you post your graphs, use a vertical scale of 45dB to 105dB and a horizontal scale of 15Hz to 200Hz.

brucek

**echomalinois** · **03-12-07, 09:52 AM**

I do not think that I have ever noticed the set target level button. Could that be the problem?

**brucek** · **03-12-07, 10:22 AM**

You need to go through the routines as I briefly listed above and see how it goes. If the levels are properly set to 75dB, it isn't very loud and the reciever volume isn't at max.

Did you do a measurement check initially after you created the soundcard calibration file to ensure that the loopback cable produced a flat response?

brucek

**echomalinois** · **03-12-07, 10:37 AM**

Yes, I did do a check of the sound car and it appears correct. When I get home I will post that here to get thoughts in case I missed somthing. Thanks yet again brucek!

**echomalinois** · **03-12-07, 07:55 PM**

So here is what I get after i calibrate the soundcard and run a sweep. http://i5.photobucket.com/albums/y16...cardgraph2.jpg

Now when I go to target settings and set target level, I get a window that states that the levels are higher then they should be with no signal present. If I press OK then another window pops up and says level change with cal signal on is less then expected. I am so lost.

**echomalinois** · **03-12-07, 09:20 PM**

So I think I got one

I am still having problems with consistency? I was able to get this one after setting target, but was not able to duplicate this for some reason. I feel that background noise has a lot to do with my problem. Noises in the house and cars going down the road may be part of the problem. I do not know how to post a picture so I will just post another link. Thanks all for the help, especially brucek. So take a look and let me know what you think

http://i5.photobucket.com/albums/y167/marcmc/graph2.jpg

**brucek** · **03-12-07, 10:05 PM**

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So here is what I get after i calibrate the soundcard and run a sweep

Perfect.

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I do not know how to post a picture

THIS STICKY will tell you how to post a graph.

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I get a window that states that the levels are higher

I don't see why if you have all the levels set and the target is around 75dB.

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So take a look and let me know what you think

Response looks very good to me:

brucek

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