Hey everyone. I suspect I have snatched up the last of the "current" stock of the A306, however that does mean that the ones that were available were some B-stock examples. According to Thomann, the equipment should be 100% working and might show traces of use, however I have noticed some buzzing from the woofer of the one unit (especially at lower volumes). I suspect this is voice coil rub, as it all but disappears when pressing on the surround at about 6 o'clock. From this I have 2 questions:
1. Are there any "soft" meathods of addressing the VC rub, such as test tones, burning-in, manipulating the cone etc. which do not involve opening the speaker (or dust cap)?
2. What would be the best way to test whether there are no other severely detrimental effects on the frequency responce of the units? I have a USB mic (but no SPL-meter), could I perform a measurement which would confirm that the speakers are within acceptable limits other that the abovementioned?
3. Given the issue, should I rather exchange these units for A305's or A308's (or otherwise)?
Thanks for any input!
Edit: I have tested by swapping the inputs and the issue remains on the same woofer, and with different sources/amps. I have also rotated the unit 180 degrees to no avail.