Home Theater Forum and Systems banner

Efficacy of a "loop-back" due to impedances

1287 Views 7 Replies 3 Participants Last post by  JohnM
Hi, I was just pondering the sound card calibration system after noticing that the 'ripples' on the loop-back measurement from my audigy 2 zs notebook look quite similar to some of the ripples in my frequency response measurement of my speaker and it hit me: line impedance... since the microphone (preamp) to sound card will have a different impedance setup than the sound card loop-back setup, will that not affect the determined frequency response? would there be a better way than a loop-back cable to measure the calibration file? many of my measurements appear to have the same ripple response in the midrange (but inverted since it is 'subtracted... could this mean that the ripple responses may be less than accurate; one would assume that if you are subtracting out something that should always be there, you would not have any 'trends' between the measurements that look like what you are subtracting out...
1 - 4 of 8 Posts
the ripples are in the midrange...

The first image is there to show the soundcard cal, the second is trying to show how both measurements seem to have a lot of the same 'problem areas'... I am presuming it is a feedback issue; how would I go about fixing that?.. basically the input (measured) is some how getting routed to the output again on the card... or is it some other type of feedback?
See less See more
I just remeasured the cal file and it appears to be much smoother now; I believe it is the exact same setup I had when measuring the first time but clearly something changed...
got it; thank you for your help Bruce and John
1 - 4 of 8 Posts
This is an older thread, you may not receive a response, and could be reviving an old thread. Please consider creating a new thread.