Андрей, я случайно нарыл в зарубежной конфе такой материал по Доплеру. Вы как-то спрашивали. Я ничего не проверял и не редактировал. Возможно, цифры и не точны. Для приверженцев одно- и двухполосной акустики это тоже будет интересно прочесть - что мы имеем, слушая ставший стандартным двухполосный громкоговоритель с 8" драйвером.
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When you sum short wavelength high frequency tones with long wavelength low frequency tones on the same cone you are adding a Doppler type distortion to the high frequencies. This Intermodulation Distortion increases with max/min frequency and Xmax can be approximated as
IMD% =100*N*Xd*Pi/Wl
where N is the ratio of the high frequency to low frequency, Xd is then amplitude of the cone motion attributed to the low frequency and Wl is the wave length of the low frequency.
To obtain low IM distortion on a 1-way or 2-way requires low Xmax from either low listening levels, multiple bass drivers, horn loading, or excursion/power restriction on the lowest octave.
A single 15" will provide 90db @1m at 40Hz with 1.7mm excursion in a monopole box. When a 90db 40Hz and 1KHz tones are summed, about 1.5% IM distortion can be generated. Easy to hear, but not too ugly.
A single 8” driver requires 6.8mm of excursion in a monopole box to provide 90db @1m at 40Hz. When a 90db 40Hz and 1KHz tones are summed, about 6% IM distortion can be generated. Getting Ugly.
--- кусь ---
--- кусь ---
When you sum short wavelength high frequency tones with long wavelength low frequency tones on the same cone you are adding a Doppler type distortion to the high frequencies. This Intermodulation Distortion increases with max/min frequency and Xmax can be approximated as
IMD% =100*N*Xd*Pi/Wl
where N is the ratio of the high frequency to low frequency, Xd is then amplitude of the cone motion attributed to the low frequency and Wl is the wave length of the low frequency.
To obtain low IM distortion on a 1-way or 2-way requires low Xmax from either low listening levels, multiple bass drivers, horn loading, or excursion/power restriction on the lowest octave.
A single 15" will provide 90db @1m at 40Hz with 1.7mm excursion in a monopole box. When a 90db 40Hz and 1KHz tones are summed, about 1.5% IM distortion can be generated. Easy to hear, but not too ugly.
A single 8” driver requires 6.8mm of excursion in a monopole box to provide 90db @1m at 40Hz. When a 90db 40Hz and 1KHz tones are summed, about 6% IM distortion can be generated. Getting Ugly.
--- кусь ---