# Loudspeaker impulse response optimization



## thadman (Mar 1, 2006)

I'm interested in what factors affect the impulse response of a loudspeaker driver, specifically the relationship between the factors.

If we are interested in optimizing the impulse response of the loudspeaker system, could we simplify the problem by parameterizing the system and separating the rear chamber optimization from the driver design optimization or are the parts interdependent?

ie could the best rear chamber design be achieved without regard to the electro-mechanical parameters of the driver? could the best driver design (impulse response) be achieved without regard to the modal behavior of the enclosure?


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## tubzrulz (May 30, 2009)

There are only two highly respected loudspeaker engineers that come to mind who consider impulse response a critical design criteria: John Dunlavy and Richard Vandersteen. But only Vandersteen takes enclosure design into account when optimizng a driver's impulse response. Starting in the Model 5 Vandersteen implemented a tapered transmission line for the midrange to minimize the rear sound wave's effect on delayed cone movement. The model 5 midrange driver (now used throughout the product line) uses a very small but powerful alinco magnet and minimilast basket to reduce reflected sound off the motor structure as much as possible. So for Vandersteen, both driver and enclosure design are taken into account with respect to impulse response.

Both engineers agree the most important aspect of achieving a coherent broad band step response is proper integration of all the drivers in the system...time alignment. This requires 3 basic things: offsetting higher frequency drivers so their sound arrives at the listener at the same time, low order linear phase crossover design (6dB/octive) so that time alignment isn't thrown off by large phase shifts in the crossover region, and proper distancing of the listener to the loudspeakers. Oh...and a sealed box. Ports do all sorts of nasty things to the phase relationship of a speaker system.

Does that answer your question?

TTFN,
Adam


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## DanWiggins (Jun 15, 2005)

For a loudspeaker driver (a minimum phase device), impulse response, frequency response, and phase response are all inter-related. Optimize one, and you have optimized the others. You would need to use non-causal processing to decouple these.

Get the frequency response flat, and the impulse will be optimized.


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## Ciucchino (Apr 28, 2009)

In order to reduce linear distortions from speaker and from room interaction u can use Sbragion's DRC.. U can find it in the net..


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## 14642 (May 19, 2008)

DanWiggins said:


> For a loudspeaker driver (a minimum phase device), impulse response, frequency response, and phase response are all inter-related. Optimize one, and you have optimized the others. You would need to use non-causal processing to decouple these.
> 
> Get the frequency response flat, and the impulse will be optimized.


 
DING DING DING...we have a winner. This IS the Fourier Transform. However...be careful--this applies to a minimum phase device only. that means one driver and no other radiating surfaces. A loudspeaker in a room isn't minimum phase. A loudspeaker with an additional tweeter isn't minimum phase either. Focusing on the impulse response at the expense of other aspects is a little like serving great wine with a bowl of microwave popcorn. 

However, one really has to screw up a crossover and enclosure design to have an impulse response that's so bad that the speaker sounds bad once the frequency response is corrected.

The more important considerations in designing a speaker system are frequency response and directivity.


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## Oliver (Jun 25, 2007)

Andy Wehmeyer said:


> DING DING DING...we have a winner. This IS the Fourier Transform. Focusing on the impulse response at the expense of other aspects is a little like serving great white Zinfandel wine with a bowl of microwave popcorn.


Umm hgh


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## DanWiggins (Jun 15, 2005)

Andy Wehmeyer said:


> However, one really has to screw up a crossover and enclosure design to have an impulse response that's so bad that the speaker sounds bad once the frequency response is corrected.


You need to spend more time at the CES High End section (now at the Venetian); you'll hear PLENTY of people with some of the highest-end, most-forgiving drivers REALLY screw up a crossover!


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