Interesting tidbit:
In a different conversation, Dennis said that he can hear a clear difference between his older Revelator 8" woofers in his personal Speakers vs new ones being installed into new cabinets for delivery to customers …
A number of years ago, Dennis conducted a simple blind listening test among a few friends.
This was posted on another audio forum, because there was a lot of chatter about Cambridge Audio Aero 2 speakers needing a lot of break-in time, especially in the tweeter's range. The Aero 2 speakers were a 2-way design with a typical 6½" woofer and a Tectonic BMR driver instead of a typical dome tweeter. (It was these speakers that first alerted Dennis that those BMR drivers had promise as a mid-range, but were poor as tweeters.)
Two newly purchased Aero 2 speakers were used. Another of Dennis's many admirers had purchased them and shipped them directly to Dennis. He opened one of them and played radio broadcasts through it for more than 50 hours. The other speaker remained sealed in it's shipping carton.
After the 50 hours, I listened to them, one at a time, in A vs. B fashion. I listened to a variety of music, without knowing which speaker had been run-in, as Dennis switched back and forth. I listened on-axis, and about 30° off-axis. I was asked if I could tell the difference between the speakers, and if so, which I preferred. It was my experience that both speakers sounded so similar that I could not tell them apart.
Immediately afterwards, I watched as Dennis made frequency response measurements of the speaker which had been run for over 50 hours and the speaker that he recently removed from it's sealed carton (see them below).
I also listened to a direct comparison of the Aero 2 which had been run for over 50 hours and a different 2-way stand-mounted speaker, the Philharmonitor. In contrast, I found it easy to hear differences between the two, especially in the upper treble range. Under the same conditions (room, listening position, electronic gear, and music selections), I could easily hear differences between the Aero 2 and Philharmonitor, but I could not hear differences between the two Aero 2 speakers.
A total of three people participated in this blind test – not enough to make any statistically valid conclusions. At the time when these results were posted, all the chatter about break-in abruptly ended. Some of the more outspoken pro-break-in posters, who had frequently boasted that they could hear the results of speaker break-in, simply vanished.
Interestingly, Dennis later told me that one of the three people who listened to these speakers did say he could hear minor differences as a result of break-in. But it wasn't in the tweeter. He said male voices sounded 'chesty' in the non-broken-in speaker, and that could not be heard in the run-in speaker. He made a living as a studio recording engineer, and had previously bought Phil 3s from Dennis. He said, in his experience, that woofers typically loosened up during the first minutes of use. The change is subtle, and it took place in the first minutes of use, certainly not longer.
That is quite similar to what you learned from Nick at Stereo Integrity .
