Can't get input to match output on calibration...

[Buknakyd]

with 80 dB ref setup with receiver and spl calibrated to 80 dB Dial set to 80 and target set to 80 dB this is what I've got:




i notice that when i leave everything as described above but click the dial down to 70 on the RS meter i can get the Input and Output just about even at -12. Would this be a better route to go?

[brucek]

Well, with the dial at 70, then the meter needle pegs at +76dB. Your highest level in your graph is about +86dB. So your meter is outputing a clipped signal full of distortion.

So, no I wouldn't do this.

If you're getting -23dB input level as you show in your picture above, while using the 80 db on the dial of the RS meter, it's gonna have to be OK.....

brucek

[Buknakyd]

thanks for your help bruce!

Now i get to start figuring out what my graphs mean and start messing with the fbq 2496

[cruzmisl]

Buknakyd wrote:

cruz,

which soundcard did you get exactly?

this thing?

Yes, I got it from Fry's online for $20 after rebates. Rebate is still valid. Strike while the iron is hot.......

[cburbs]

I am using Vista and the Soundblaster MP3+ and I get the following cal file - does this look ok? I have the same issue when setting up - reference the second pic for my setup info when calibrating the soundcard.

[brucek]

Yeah, it's good. You actually have a very good low frequency response with that card (as evidenced by the squiggles between 0Hz-10hz). To correct this squiggle problem in the final soundcard cal file, you need to extend the Impulse Response window so that more of the response is included. Extend it until it's a bit smoother and then save the file.

To do this, run the soundcard cal routine and get to the spot where you are about to click Finish. Don't click Finish, instead click the IR Windows ICON in the upper right corner of the REW screen. A popup will arise and it will show the pre-window as 125msecs and the post window as 500msec. Extend the post window longer, and as you do, you'll see the Frequency Resolution result lowering. Change the window to something like 1000msec and click Apply Windows while watching your squiggles. See how it's smoother now? Hit Finish on the soundcard cal routine and save the file. Your measurements will be more accurate down lower now.....

Don't extend the window too far or you'll begin to pick up noise in the soundcard response. Watch for this. In fact, extend the window way out to maybe 1500msec and see if noise begins to appear in the response. Anyway, somewhere around 750-1000msec should be fine...

brucek

[cburbs]

Ok so in order original scal, 750 scal, 1000scal, and 1500socal, and now 1250 so cal. So which one should I use? again thanks for all of your input on this forum - it is great that people can share there knowledge with each other on different HT stuff.

[brucek]

You're starting to show some noise in the signal as you can see. Personally I would first attempt a few soundcard calibrations at a few different Check Level settings and try and clean the signal up first. I find my card gives the best response when the routine shows about a 3dB headroom.

Then apply the longer impulse window to the result once it's cleaned up a bit. See how your signal is starting to want to oscillate evidenced by the thicker line above 10KHz....

Test different input volumes until you get the best response....

brucek