WARNING: From the Desk of the Secretary of the Interior Ultrasonia
This post may contain OT and unauthorized humor or other comments. Read at you own risk. (If you don't know what this refers to, no need to ask as its simply a private joke relating to another Ultrasone thread. But it does apply to those who would want to act as thread police.)
Since I have had experience with 2 of the three dead Ultrasones (2 - 750s & 1 - 2500), I thought I would recap.
First dead 750 was at a pro audio shop. Obvious mishandling as the velor was torn on one cup. Both speaker cups played music and both had some bass, but very weak bass. But the rest of the speaker response seemed OK. I checked the cable on 2nd visit and this did not seem to be the issue.
My dead 750: (To the best of my recall) First 10 hours was music played at normal volume. Next 24 hours or so wass continuous loop music out of iPod>Hornet at slightly louderr than normal volume. Approximately 35 hours started continuous loop of Track 58 (no pause in between) at slightly higher than comfortable listening volume. I played this continuously 24/7 except for the times I was listening to music for about the next 10 days. After that I went back to music 24/7 for 2 days then music only when it was listening which was only 10-12 hours over 2-3 days.
Additionally, for most of this time I was simultaneously "burning in" some very old (8-10 year) Senn HD-25 SP, and a very low hours (maybe 2-3) set of KSC75s (purchased 4 months ago). The only difference was that much of the time the Singlepower Extreme was the amp for the 750s and the Hornet was the amp for the Senn HD25 & KSC75. Checking these 2 HP now and everything seems fine with them.
A few times, due to the logistics of my set up and not wanting to turn off/on tube HP amp and tube phono preamp, I pulled out and later put back in the line out plug on my iPod dock with all 3 sets of HP attached. I know this can give a sudden electrical buzz sound that is unpleasant to hear. I don't know if that is enough to cause a speaker failure (but why only on Ultrasones?), but Terry seemed to indicate that it wouldn't in a previous post. (Terry, please correct if given the greater details this changes your opinion.)
So this sure looks like an Ultrasone quality control issue to me. I hope that this isn't the case as I have found a line that I really love, and I want the love to continue (maybe eventually with some Edition 9s). At the same time, I don't think there is any reason to hide this type of information. I don't have any stock in Ultrasone. If there is an issue with quality control it might as well be known. That makes it part of the buying decision for new folk as well as for upgrading decisions.
Secretary of the Interior Ultrasonia