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Copyright 2007-21 © Troels Gravesen
The following few
graphs and pics are meant to give a little advise
regarding driver measurements. How is the microphone
going to be mounted and what about the tweeter?
First of all:
I cannot enough recommend reading the
articles written by John Atkinson at Stereophile:
The good question is how smooth the rod + mic has to be not to reflect soundwaves back to the microphone capsule. Here's an example of how little it takes:
As can be seen this tiny reflector seriously compromises the tweeter performance.
Vifa XT25TG measurements
Above is seen what we should not do. No flush mounting of the tweeter. Just cutting a hole for the magnet leaves a 4-5 mm step from the tweeter face plate to the baffle plane. The result is seen below.
Response of XT25TG from non-flush mounting. Quite a difference. Below the two readings on the same graph:
Above the impact of flush mounting a tweeter.
This is what it should look like. Rebate a little deeper than the height of faceplate, add some rubber strips and screw the tweeter in place until the faceplate is flush with the baffle. No more, no less. Not 0.5 mm below and not 0.5 mm above. Flush!!
Make sure the rebate has the exact diameter of the faceplate + 0.1 mm. If wider you can use tape to cover the ditch. Even a narrow ditch will cause response irregularities.