Home Theater Forum and Systems banner

Full range sweep - odd graph

1985 Views 7 Replies 4 Participants Last post by  davidbrn
I've just been having a go at doing some full range sweeps, with a view to producing some convolver filters for use in J River. The graphs though look really odd - there's a 25db drop off from 7k to around 250. My speaker should roll off at around 55, so I can only assume I've done something wrong.

I'm measuring with a Behringer ECM8000 mic connected to a Behringer MIC100 valve pre-amp, and an M-Audio Audiophile 2496 soundcard. The sound card calibration looks 'normal' i.e similar to others on here, no mic calibration file.

Any suggestions?

Text Blue Green Line Pattern
See less See more
1 - 4 of 8 Posts
Thanks for the suggestions. Tried both, no appreciable difference. I've also tried my on-board sound card instead of the M-Audio, again, no difference. I'm going to get hold of another mic preamp to see if that makes a difference, and if not, another mic.

I have the XLR output of the MIC100 connected to the RCA in of the sound card with an XLR-RCA adapter, which is what your describing. I'll report back when I've got a 1/4" - RCA adapter to use the preamps other output.
Update on what I’ve found.

I ditched the XLR-RCA converter and got a mono ¼” plug to RCA socket converter. This was plugged into the MIC100 and then an RCA cable to the PC. Disappointingly the result was no different to the first graph.

I did note that using this method the “Gain” and “Output” dials on the MIC100 both had to be turned to their maximum setting to get a usable reading, which I suspect is not normal.

Next attempt was to swap the MIC100 for an ART Micromix, again using the ¼” plug to RCA socket converter. Instant success. I only did a quick uncalibrated test to see what the shape of the resulting graph would be, and it looks much like expected, with a largely flat response. The massive drop off has gone.

I think that either
a. There is an incompatibility somewhere with the MIC100, but I have no idea what it could be.
b. I have a faulty MIC100

Thanks for your suggestions, all I need now is to get the house to myself for a morning to do some proper measuring.
See less See more
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.