B3N, -12db dip at 4.00khz -> 4.04khz, problem?

[mintos]

I was doing some crossover modeling and noticed a sudden -12db dip at 4.00khz, 4.05khz with the B3N and BC25SC06-04 tweeter. I can't get rid of this as it looks like a big breakup node with the B3N. Is that really an audible issue? Seems like the dip is in a very very narrow range.

[JonMarsh]

Mostly likely a measurement artifact, either physically or in software.

I find it helpful to do nearfield measurements of drivers first, to establish their behavior, then keep that in mind when working with the cabinets and far field measurements. For example, a high level large area diffraction event can cause a sharp dip or peak in the measured response; the closer it is physically to the driver origin, the higher the level and the greater the peak or dip, depending on whether the interference is constructive (in phase) or destructive.

That's another argument for working out the acoustics of a design BEFORE starting crossover work- i.e., diffraction control, any cabinet panel tweaks, and installing the planned grille cloth. That way the crossover design takes all the final design elements into account.

[Dave Bullet]

4Khz is approx 8.5cm. Measure 8.5cm out from the centre of the tweeter (all directions parallel with the baffle obviously). See if you strike 2 edges at the same offset or possibly a cavity effect from the B3N.

[fjhuerta]

It does seem like a measurement artifact.