Originally Posted by kzhtoo
Hi Tigger, appreciate it as always!
2) I approximated the microphone at ear height with upward position. But regardless today I rerun ARC again with more precise mic positioning. The result still turns out to be the same for high freq roll off above 10kHz. I even did a quick measure for the fronts to see if other area in the room is different. Focal 1008 Beryllium tweeter is supposed to be very good and my ears do agree, but it just doesn't seem consistent with ARC freq sweep. Yes, the spec is up to 40kHz according to Focal - they believe even though freq > 20kHz is not audible, it should help improve the efficiency at high end.
And you're right in that tweeters are okay. My guess is if either one of them is blown, ARC would show error during the sweep. I'm puzzled why the curve turns out to be that way. I'm just afraid something might be broken that I don't know of. Maybe it's the room not being treated??One other thing is 1008 Be are rear ported. Currently I have the rear 2 feet away from the front wall. Maybe moving out might help. But it's too late to try today.
4) I guess I could wait on the official firmware release. This is not the main concern at the moment.
I attached my new ARC run below. All 3 level calibration for fronts L/R and sub are at 0.
Again, thanks much!
ARC will not throw an error, just because a speaker is blown (unless something is really wrong). It will however show you the speaker is not responding in the frequency range it covers. (If the whole speaker itself, not just one of the speakers in your speaker, is dead, than ARC will not detect anything from that channel and will show an error).
As for the speaker being more efficient because it goes higher... sounds like marketing and sales BS to me... but I would love to know their logic to that statement.
The rear port will have no effect on the Tweeter. The port is for your woofer. The tweeter (should) be a closed back and therefore completely independent of the port, speaker cabinet or any of the rest of the speaker cosmetics (short of someone putting a grill cloth over the tweeter that absorbs high frequencies).
Room treatments will have no real impact on the tweeter, except to help reduce reflections of high frequencies (which would cause you to lose volume in the higher frequencies, not gain it). Unless of course by treatments you mean removing any sound absorbing materials in your room and applying hard reflective surfaces... not a good plan in most cases.
As your old speakers (in presumably nearly the same location) had no problem going higher, what you are seeing is the result of the new speaker design. Not the room.
Again, the specs say the speaker will play at 40kHz and I don't doubt that, but at what volume? If they hit 40kHz at 50db down... your graph would likely look like what you are seeing. I would contact the speaker manufacturer and ask them for a graph of the speakers frequency response up to the 40kHz point. I would also ask them what the crossover frequency is for the tweeter. If it is around 3-4kHz (which I'm guessing it is) than your tweeters are working just fine. If it is around 8-10kHz, than yes, you may have an issue as it basically looks like your tweeters are rolling off at that frequency.
Out of curiosity, have you tried placing the ARC mic about 5-6 feet directly inf front of the tweeter, at the exact same height as the tweeter, and doing a sweep there? You can use Quick Measure to do this. I would be interested to see that graph.