I'm building a MEH waveguide speaker with a Celestion TF0410MR midrange. While measuring the frequency response of the TF0410MR on the waveguide I noticed a 2nd order distortion peak @~900Hz. I measured the driver without the horn and the peak still existed. Both of the TF0410MR that I have show the same distortion peak. Is this normal for this driver? The power level is ~ .25 watt, measured at 1 meter.
Attachments
I have have some data from my own MEH:
BM-D446 on PH-4220
(attached apologies for the weird vertical picture, REW is picking up my vertical display).
the levels are the actual level with a UMIK-1 adjusted for 1m taken outdoors. The crossover is at 1.27kHz (acoustic) so the midrange looks a bit lower distortion than the tweeter with a peak in distortion -36dB from fundamental at 614Hz (1.5%). Almost all the distortion is 2nd harmonic in my results whereas at times your 3rd harmonic is exceeding the 2nd at times in your results. Your results look to be overall lower distortion, about -45dB from fundamental?
When measuring distortion you need to perform the measurement away from other objects and time gate, are you doing this?
BM-D446 on PH-4220
(attached apologies for the weird vertical picture, REW is picking up my vertical display).
the levels are the actual level with a UMIK-1 adjusted for 1m taken outdoors. The crossover is at 1.27kHz (acoustic) so the midrange looks a bit lower distortion than the tweeter with a peak in distortion -36dB from fundamental at 614Hz (1.5%). Almost all the distortion is 2nd harmonic in my results whereas at times your 3rd harmonic is exceeding the 2nd at times in your results. Your results look to be overall lower distortion, about -45dB from fundamental?
When measuring distortion you need to perform the measurement away from other objects and time gate, are you doing this?
Attachments
kipman725,
Thanks for the data. I'll rearraign my testing setup and see if that has any effect on the 900Hz spike.
Thanks for the data. I'll rearraign my testing setup and see if that has any effect on the 900Hz spike.
