first few graphs,...feedback please

**trofius** · **10-22-07, 08:20 AM**

Ok i have finallly done a few graphs.

My sub is a DIY job with two peerless 830952 12inch drivers in a 125L sealed enclosure, running a 1000w Dayton amp.which has a built in rumble filter at 18hz...

anyways i was told there might be something wrong with my sound card cal, it took for ages just to get the input out puts setup.

the upper wiggly line is the corrected measurement, with 1:1 smoothing
the solid lhorizontal line is the 75db target
the solid dark line is the spl meter correction
the dotted line is the sound card calibration correction.

sub at 1m set SPL to 75dbamp gain is on 1

As heard in the listening position, gain on amp cranked all the way up to....3!

I have left all the settings at this stage at 0 i played with dropping the db at 20hz down by 10db but it doesnt change that much as it drops the roll off a lot sooner.

I will have another play and see if i can get the sound card cal better, then if its not so jumpy i wont need the 1:1 smoothing on the sub plot, does that sound correct?

**JohnM** · **10-22-07, 08:32 AM**

The sound card cal is just noise, looks like you didn't succeed in getting the signal routing correct. You need to get that right before taking any measurements.

**Otto** · **10-22-07, 08:41 AM**

Yep, I agree with JohnM. When correct, the soundcard cal will look something like a flat line until you zoom in, and then they will frequenty roll off at the low end. There won't be all that raggedy-ness.

Oh, one other thing, limit your vertical axes from 45 to 104 dB. It makes viewing easier since we use that range for most people -- more "apples to apples."

Good luck!

**brucek** · **10-22-07, 10:18 AM**

Quote:

anyways i was told there might be something wrong with my sound card cal, it took for ages just to get the input out puts setup.

Hopefully for the loopback cable, you used a stereo type. The connectors are always stereo on soundcards.
And hopefully you were using the line-out to the line-in jacks on the soundcard, and not a mic-in.

brucek

**Wayne A. Pflughaupt** · **10-22-07, 05:35 PM**

Don’t forget to re-scale your next graphs for a 45-105 dB window before posting

Regards,
Wayne

**trofius** · **10-23-07, 09:33 AM**

thansk all for the replies, sorry about the graph sizes..

Yes i am using a stereo cable for the loop..

the soundcard has 3 input/output plugs 3.5mm jobbies, all these are fully assignable, so i just hav eto set what each plug is being used for, when hooked up for the sound card cal should the input be as a wave as when measuring or just a line in...and the same with the line out, for meauring it only works when set the speakers l/r and not as line out. so keep it all the same, when doing the card adjustment as well as the measurement?

there are some pics of the subs construction here
http://smg.photobucket.com/albums/v334/Trofius/stuff/

thanks..

**clubfoot** · **10-23-07, 04:42 PM**

Also take all sub measurements isolated from the mains, at your listening position,...so we can see what the sub is doing in your room/location,...first.

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