Subtracting FRD curves in REW/VituixCAD

[Ilkless]

So some of you might know I have a pair of SEAS Idunns that had a modified baffle (crucially the same CtC). I got VituixCAD-simmed diffraction of the stock baffle and the modified baffle. I want to subtract both curves to see the difference between the original baffle diffraction and the new one. How does one do it?

FWIW the new baffle peaks and dips at the right places - there is a minor 1kHz dip and 2kHz peak off-axis on the stock speaker which the modified baffle balances out. I want to use the subtracted curve as a sort of compensation curve on SEAS' measured Idunn response to show the estimated effect of this new baffle. Any ideas?

 

[QMuse]

So some of you might know I have a pair of SEAS Idunns that had a modified baffle (crucially the same CtC). I got VituixCAD-simmed diffraction of the stock baffle and the modified baffle. I want to subtract both curves to see the difference between the original baffle diffraction and the new one. How does one do it?View attachment 51255

FWIW the new baffle peaks and dips at the right places - there is a minor 1kHz dip and 2kHz peak off-axis on the stock speaker which the modified baffle balances out. I want to use the subtracted curve as a sort of compensation curve on SEAS' measured Idunn response to show the estimated effect of this new baffle. Any ideas?

You can try this with REW: under All SPL tab click on Controls/Trace arithmetic. Select curves and operation you want to be done with them.

P.S. You may want to try A/B operation instead of A-B. If you want to apply resulting curve as a filter to the other curve use A*B.

 

[Ilkless]

You can try this with REW: under All SPL tab click on Controls/Trace arithmetic. Select curves and operation you want to be done with them.

P.S. You may want to try A/B operation instead of A-B. If you want to apply one curve as a filter to the other use A*B.

Thanks! Worked perfectly.

 

[QMuse]

Thanks! Worked perfectly.

No problem, I'm glad it helped.

 

[Ilkless]

Green is with the modified baffle. The SEAS distributor that built it has some dubious ideas like running magnesium Excels with a first-order, but seems like he did his math for the baffle and it checks out (this was before I started learning to sim so I couldn't check before build), flattening out 500Hz-3kHz significantly. We also decided on a bit more padding resistance so the response above 3k should be a tad more subdued. Lower sensitivity. We also put the U18RNX/P in a 24 litre enclosure instead of 20.