KM84 revisited

[Chrisfromthepast]

In the meantime, I acquired a real KM84, but it needs repair. If it isn't the capsule, then I guess I will be able to fix it.

Id love to hear some off axis tests, even if the datapoint is an outlier, I love to see some data.
I haven’t been keeping up with my measurements lately, and will be performing some more sweeps soon. I can probably grab some larger speakers from rental inventory and get higher spl measurements than I was able to achieve with the Genelec.
I typically do 8” from a coaxial source and get up to 110db before limit.
L-acoustics x15”s are very flat when mounted on a pole, I’ll see how loud I can make my test rig. I could try k2 at 24” but i worry about room noise and the contour would need to be flattened in network manager before testing.
I want to measure at extreme spl because all of my km84 home builds pass the voice test, but sometimes have trouble under real world spl.
Is there a test prescription we can agree on before I contribute meaningless results?
So stoked on this final chapter to my km84 journey.

 

[jp8]

Interesting! Will you be using the 3U/CM-63/KM84++ for this test? The off-axus response of the 3U capsule is supposed to be quite good. Better than the stock CM-63 capsule.

I designed the KM84++ for a max SPL handling of 140 dB with the pad engaged and assuming a 3U cardioid capsule. That's 10 dB up compared to a classic KM84. If you want to further increase the max SPL handling, you can reduce the mic sensitivity by taking a higher value for C2 (Which can be done on any KM84 incarnation, btw. Not just the KM84++.). This is a major advantage of the the charge amplifier concept as opposed to the voltage amplifier circuit of e.g. the Schoeps circuit: Schoeps has fixed gain, whereas the KM84 gain can be tweaked by changing a single capacitor.

Jan