some issues figuring this all out

[ccdoggy]

Hello. I am attempting to use REW to get a good idea what my sub is doing in my room, and maybe eventually get a BFD to help out a bit. but being a poor college student i would rather see if i need one first ( although i am sure i do).

Here are my questions/problems.

1. so i started playing around with it and i attempted to calibrate my sound card. I built my computer and when i did i made sure i got a motherboard with a good sound card on it, which might pay off in this project... maybe not you tell me. When i connect the heaphone jack to the line in jack (using a 1/8" stereo cable, little long) and i hit the measure this is what i get http://www.ccdoggy.net/temp/soundcard.jpg . I have in the options output is 48Khz, output is my Nvidia nForce Audio, Headphone output, Input is same sound card and Line_IN. I have changed nothing else. what am i doing wrong?

2. Because I always use my Digital coax connection to my Arcam receiver shouldent i make the connection from the computer to the receiver, then from the receiver's pre outs to the sound card's Line_In? then do the sound card calibration? or should i not do it?

3. Just to confirm, inroder for me to connect aRS SPL meter (old) I need a RCA to 1/8" fono cable to get it connected?

THis program really looks awesome and extremly helpful, i cant wait till i can borrow my buddie's RS spl meter and get measurin.

Thanks allot for the help!

[Otto]

Hi Steve,

Do the soundcard cal first. You do the soundcard cal with no processor in the loop; just a cable from audio out to line in. After that, you should be able to do a loopback measurement and get a flat line.

We generally don't use digital connections because you can't cal your soundcard with the digital out and an analog in. Just use the analog for now; it's plenty accurate enough.

Yes, you will need a single RCA to 1/8" jack. Don't use RCA to mono 1/8". User RCA to stereo 1/8". You will generally go in on the left side of your input; that's the default of REW, so the most commonly used.

[ccdoggy]

so is that graph reasonable for before calibration?

Thanks for the info!

[brucek]

so is that graph reasonable for before calibration?

No, you need to first do a soundcard calibration.

Then you need to ensure the soundcard calibration is correct by doing a response check of a loopback cable. You should get a flat line if all is correct.

Then you remove the loopback and do regular measurements with an SPL meter using the correct calibration file for the meter that you are using..

brucek

[ccdoggy]

thanks for the help, ill get to trying it all out tomorrow some time. and i am sure i will be back with questions and graphs galor.