Re: More to a measurement then the transfer function?
Hi Dave, I really am far to much of a noob when it comes to measurement, but i have been hitting it pretty hard lately...asking myself the same questions you pose...
Here's as much as I've been able to gather....please correct !
Starting with a snip from one of Dave Gunness' patents http://www.fulcrum-acoustic.com/assets/pdf/whitepapers/us8081766B2-creating-dsp-filters-improve-transient-response.pdf
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If I understand the patent, blocks 40 and 41 are about finding driver resonances, horn reflections, etc,... that are NOT minimum-phase (IIR) fixable.
It appears Dave calls these driver specific fixes LMA's (Loudspeaker Mechanism Algorithms.)
I don't see how a transfer function can measure this, hopefully somebody can chime in.
I think an impulse response, along with a time sensitive spectrograph or something similar, could show it....
Blocks 42-45 seem to be about more well traveled technique. First use minimum-phase eq, either IIR or FIR replicated IIR.
Then, instead of IIR crossovers, use linear-phase crossovers. Then, keep iterating till your're happy.
I think Dave calls these steps LSA's (Loudspeaker System Algorithms).
To me, 42-45 are what we've been doing all along,....... only as suggested by the patent, crossover is now linear-phase via FIR;
and eq is still done via minimum-phase, but implemented with either FIR or IIR.
I think this tuning is the domain of the transfer function.
I've been having a lot of luck with 42-45, measuring with transfer function, and then generating FIR for both linear-phase crossover, and minimum phase eq.
What I Really want to learn, is how to measure for blocks 40-41, and then how to insert them into FIR generation.
I think that is what you're asking too... right?
Thx, Mark
