[wahfreak]

Hi,

Nice to be here.

I'm measuring a room for recording. This graph is a "before" construction and after I'm done I'll measure again. I just wanted to make sure what I did was correct or at least check with some who could offer help if needed.

I hope I can explain this right. I'm using a Presonus Firebox recording interface as my "soundcard" which goes to my computer via Firewire. I had an issue trying to use a Y adapter at the Line-in. I got some funny readings doing it that way. I ended up doing the calibrations using only the loopback cable and when I was ready to run a measurement, I unplugged the loopback cable, plugged in the SLP into the Line-in and ran the measurment. I assume the Y adapter is just a convenience factor right?

The other question is I have is, once the calibrations are done and saved, there is no reason to perform these again right. Of course unless I change a soundcard or mic/SPL. Next time I want to measure my room I just open REW, call up the calibrations offsets, plug my mic/SPL and measure right?

Oh, I'm using an RS digital SPL meter.

Thanks in advance!

 

[Wayne A. Pflughaupt]

Looks good, but we like to see the graphs scaled as 45-105 dB vertical. Keeps everyone on the same page, know what I mean?

I assume the Y adapter is just a convenience factor right?

Typically it's only required for non-pro soundcards that use stereo 3.5mm jacks for the left and right channels. I doubt that will be the case for your interface.

The other question is I have is, once the calibrations are done and saved, there is no reason to perform these again right. Of course unless I change a soundcard or mic/SPL. Next time I want to measure my room I just open REW, call up the calibrations offsets, plug my mic/SPL and measure right?

Right, right, and right.

Regards,
Wayne

 

[brucek]

I ended up doing the calibrations using only the loopback cable and when I was ready to run a measurement, I unplugged the loopback cable, plugged in the SLP into the Line-in and ran the measurment. I assume the Y adapter is just a convenience factor right?

Can you expand on this statement - just want to be sure that you're not on the wrong page. Let me first explain the loopback cable.

The loopback cable is installed only to produce a soundcard calibration file. It is placed on the right channel and the soundcard cal routine is run and the file saved. The loopback is removed and that right channel is now calibrated. The SPL meter is plugged into the right channel line-in and the output of the right channel line-out goes to your system and a measurement is taken. The left channel is never used. The Y adapters are used when the line jacks are stereo and need to be 'broken-out' to right and left.

brucek