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Hello all , this is my first soundcard test measurement , does this look good or right ? - I want to make suer this is good before I continue
soundcard test 2.jpg
 

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Discussion Starter #3
Thank`s , yea I just did a test against the cal-file for comparison and thought this was the only way to post it here , I do have a graph saved with the 0hz - 20.000hz though
 

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soundcard test.jpg Here you go, Question- I have a bad hum when connecting my PC to pre for testing and sins I only want to test my sub would it be OK to use my radioshack ground-loop isolator?, sins that is all I have at the moment- just to get me started working with WER , I have a clean box on it`s way , but it will not be here till next week , any thoughts . Note: the isolator says it wont diminish the audio quality , but I don`t no how true that is
 

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would it be OK to use my radioshack ground-loop isolator?, sins that is all I have at the moment-
I would test the response of the ground loop isolator with REW first, so you know its effect. I don't expect it has a very good low end response. Just test the isolator the same way you test a loopback cable with a soundcard calibration file in place and a meter calibration file cleared, so just as a loopback cable returns a flat line, if you insert the isolator in the loop REW will graph its response.

Note: the isolator says it wont diminish the audio quality
Depends on the bandwidth they're referring to. I'm sure it's fine from 50Hz-10KHz... Test it out. If it's bad, then create a soundcard calibration file with the isolator in the loopback and then when you use the isolator, you use that compensating soundcard calibration file.

OK, tell us what the green line is? :)

strange signal.jpg

brucek
 

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Discussion Starter #7
Thanks for the help I will try that and for that green dip I do not know I`m just learning this stuff , but here is the hole pic , on another note though after redoing the cal. That`s gon from the graph sundcard test measuring.jpg
 

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The soundcard calibration file looks fine.

Note, after you run a Check Levels routine, the next step is to run an SPL Calibrate routine. This step is required whether measuring a cable in a loopback or measuring using an SPL meter.

brucek
 

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Discussion Starter #9
Cool, thanks I thought it was , but wanted to be suer - there is a bit of a learning curve but I think I`m getting the hang of it , the wife has the next 2 days off so I will have to finish up and try my first measurement after that , again thanks for the help guys and for REW too
 

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OK guys , I did a soundcard cal with the rat shack isolator , so what do you think-Good to go? I`m pretty suer it is , but would like your thoughts before proceeding ,thanks soundcard and choke cal.jpg
 

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I did a soundcard cal with the rat shack isolator , so what do you think-Good to go? I`m pretty suer it is , but would like your thoughts before proceeding
Well, at low frequencies (where you're concerned with your sub) the response of the isolator is quite good. The combination of the soundcard plus the isolator (the graph you've provided) isn't down much more than a 1/4dB at 10Hz, so I probably wouldn't concern myself and simply use the soundcard calibration file you created before. It was definitely worth testing though - now you know....

brucek
 

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WOW that`s good to know , you guys are awesome!!! thanks for the quick reply now it`s time for me to setup the BFD and start measuring and Eq-ing , I`l post my results when I`m don , but my sub is not to great - I built it back in the early 80`s and it`s only good to 35hz then drops rapidly after that , but still I can fix the gain in though`s three areas till I get my emotiva subs -when ever they release them , hoping by x-mas ,anyway here`s my sub measurement 15 inch sealed sub 1.jpg
 

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Use a measurement range of 0-200Hz when you measure a sub, so that you can see how it tracks the crossover target - don't limit it to 80Hz..

In your case, the sharp dip at ~ 23Hz is where the signal is into the noise. You can ignore the information below that - it's simply noise.

You do have a couple of peaks at ~38Hz and ~52Hz that you can work on by positioning the sub at various locations (if possible), or you can equalize them out with your BFD.......

brucek
 

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Discussion Starter #14
All right I took another measurement like you said and here it is , I thought I would of gotten better low end extension sins it`s in the front right corner , but I guess that`s more of a function of the subs capability and why I have though`s peaks ,as for moving the sub the wife says no way , thank for all the help and I guess it`s time to do some EQ-ing
 

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A couple tips....

Don't use any smoothing on sub graphs - you need to see what's going on. REW will not make proper filter decisions with smoothing on.

Always display your sub graphs with a vertical axis of 45dB-105dB and a horizontal axis of 15Hz-200Hz.

brucek
 

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Discussion Starter #16
OK thanks for the tip on smoothing I did not know that , sorry about the graph I thought I deleted one of them - I guess I should have used the preview , well my time has run out for today , but you will hear from me tomorrow I`m suer ,again thanks for all the help
 
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