How can one speaker driver reproduce multiple frequencies?

January 20, 2019
 by Paul McGowan

2 comments on “How can one speaker driver reproduce multiple frequencies?”

  1. Hmm doppler distortion, isn't that similar to intermodulation distortion in an amplifier? My thoughts are the main reason for crossovers are to keep the lows out of a high frequency driver that is designed to produce better sound in the high frequency range while improving it's clean power producing capabilities by removing the lower frequencies it cannot produce accurately at high volumes and to not damage that high frequency driver with low frequencies. Do these minor differences in distances to the ear at different frequencies in a full range driver really matter and can we hear it? Isn't it more important to have less crossover in the signal path then this doppler effect caused by a single driver given that driver has the ability to accurately produce the many more frequencies it's called on to produce? Even in a two or three way system your going to have some crossover crosstalk leaking into the other drivers more or less depending on the slope of the crossover. Moreover in a two or three way speaker how do you know the distance from the woofer, midrange, and tweeter are all arriving at your ear at the same time giving their different placements on the baffle up down left right forward and backward of the baffle? The throw of a single driver might be one half inch to one inch maybe two inches in some extreme cases which seems more acceptable to time alignment then the distance effects created with separate drives with less doppler effect at frequencies further away from the crossover point which would give a more difficult time alignment to solve. Some of that seems to be solved only in two or three way speaker systems where the drivers are all lined up in the middle of the baffle and tipping the speaker back slightly. I was really never a big fan of that kind of time alignment which is why I prefer a simple two way speaker with a tweeter very close to the woofer and a minimal first order crossover which simply removes the lows from the tweeter. You can adjust with speaker stands. I think you get great coherency and low phase effects out of such a design. Doesn't it also make integrating a subwoofer to sound coherent and free of phase anomalies very difficult?

  2. Following up on my previous post it also seems that the doppler effect is more of a problem at very loud volumes where the throw of the woofer is at it's extreme point. That can be greatly reduced with the addition of multiple drivers that keep the excursion or throw of the driver much less producing lower distortion and lower doppler effect. That might be that effortless sound we like in speakers with multiple drivers. I feel that the best design is many 6 or 8" woofers aligned on the front baffle with an equal number of tweeters. Not only will that improve doppler distortion and other distortions making the sound effortless but all of those smaller woofers in a large cabinet should also take care of the need for a subwoofer with the improvement in bass definition and coherency due to lower phase anomalies while smaller low frequencies drivers can respond more quickly then a 10 inch or larger bass driver that needs a servo device to lower the distortions caused by a larger driver.

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