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Author Topic: Transient response?  (Read 1183 times)

MikeHarris

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Re: Transient response?
« Reply #20 on: March 02, 2021, 04:16:23 pm »

the Crest 9200 shamed the Crown too.
They did variable rails much better
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duane massey

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Re: Transient response?
« Reply #21 on: March 02, 2021, 04:52:53 pm »

Interesting tidbit: when we built the 20hz horns in the mid 70's each one held 5 TAD 1602's. Each woofer was driven by approx 85 watts, and the excursion was so small that you had to shine a flashlight on the cone to even see the movement (if you could stand to squeeze into the throat while it was working).
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Duane Massey
Technician, musician, stubborn old guy
Houston, Texas

Marcel de Graaf

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Re: Transient response?
« Reply #22 on: March 04, 2021, 02:33:18 pm »

Interesting tidbit: when we built the 20hz horns in the mid 70's each one held 5 TAD 1602's. Each woofer was driven by approx 85 watts, and the excursion was so small that you had to shine a flashlight on the cone to even see the movement (if you could stand to squeeze into the throat while it was working).

This is efficiency related. Hornloading a driver in the right conditions makes the driver have less excursion for a given output compared to direct/vented system. Its as Ivan mentioned if a speaker has more excursion for a certain frequency, than this speaker must be faster as a speaker with less excursion at the same frequency. Hornloading usually make`s the low frequency part sounding a lot cleaner as there is less distortion produced by the speaker.

We all know the classic 808 kick drum.  This has some high frequency content in the beginning of the waveform followed quickly by a decay off low frequencies. To ideal reproduce this kick drum (and make it absolute tight or "punchy") the high frequencies has to come from the same acoustic center as the low frequencies. I always wondered if it would not be a big  improvement for the listener as this full kickdrum is played back in a different track layer where only the full kickdrum is reproduced by a wider bandwidth subwoofer (multiple drivers). Maybe other problems occur.

Coming back to the low frequency driver itself. I always keep my eyes out for the highest -3db point of the motor structure itself. If you would dismantle the loudspeaker cone and suspension you are left with only the voice coil. This part has only the resistive part of the wire winding and the inductance formed by the coil. The formed circuit has some time delay on its own, usually called the electronic time constant in the world of servomotors. This time constant is the time the motor reached 63% of his max. current to its inital step response. The formule for the time response of the motor alone is L/R and this can be converted back to the real -3db frequency point of the loudspeaker, but be aware this usually not shown in a frequency chart of the loudspeaker, because directivity (and/or a combination from other effects) is make the speaker looking flat. The time constant of the servodrive subwoofer is incredible low.

And than there is the issue the inductance is not constant over its frequency range. It will always be a big can off worms. A good reading about the importance of the subject is in the following link; http://aespeakers.com/designing-for-low-distortion-lambda-001-motor/

gr. Marcel

 
« Last Edit: March 05, 2021, 05:47:41 am by Marcel de Graaf »
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ProSoundWeb Community

Re: Transient response?
« Reply #22 on: March 04, 2021, 02:33:18 pm »


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