Does this mean a driver such as those in the MBL omnidirectional speakers will have the same excursion at 20hz as 20khz? We would not see the typical reduction in excursion with increasing frequency we are familiar with?
I use both methods. Sometimes the results are interesting; mainly when you're testing powered speakers with a limiter.
Not at all.
The high frequency is more attenuated by the distance then low frequency waves, just compare they're wavelengths. And you might imagine why/how.
We are often used to this being compensated by beaming from the baffle surfaces etc, narrowing directivity in the top end.
Excursion rises by a factor of 4 pr. Octave you go down in frequency.
Try playing around with the link under , for some visual confirmations.
https://www.baudline.com/erik/bass/xmaxer.html
Thanks for taking the time to chip in. Since you are here, can I ask if you have any insight as to the mechanism behind tweeters showing compression at the top octave despite excursion not being a limiting factor? (and not limited intentionally by electronics etc).
My eye was drawn to this in the TAD data because of the lack of other compression, but it is present in many speakers, Wharfdale Super Denon for example. Also not present in some others, such as Kef Reference.
I'm so far leaning towards a limit of acceleration (corner mass) or deformation of some part such as the VC former. It could be thermal, but since you use short sweeps it would probably be some kind of instantaneous resistance change in the VC, rather than heat soak. There was also mention of t he magnet structure being saturated at HF by VC currents. While the multi-tone compression is more representative of music power spectrum, it doesn't help curious minds figure out the mechanism going on here.
It’s power compression and a result of the smallish voice coil found in tweeters……thermal compression can effectively be countered with the ferrofluid…..but the reduced size of the VC typically cannot be overcome.
What’s most interesting is that your ear/brain mechanism does the same thing at higher listening levels…..i never really consider power compression for home systems, but for commercial sound at distances, it matters.
What’s most interesting is that your ear/brain mechanism does the same thing at higher listening levels…..i never really consider power compression for home systems, but for commercial sound at distances, it matters.
The more I think about this, I guess you meant in practical application rather than 'by definition'?
Where a direct radiator already shows an omni-direction polar response, I would not expect to see 6dB/Oct rate of change in response by adding a CD horn - just as adding an infinite baffle to a direct radiator boosts everything below the baffle step freq. by 6dB, not 6dB/Oct. Only in that transition range from omni-directional to directional (the baffle step region) will there be a slope to the SPL boost / cut.
I don't mean this to be argumentative, I only want to understand clearly as I took your statement to be one of a base level theoretical definition.