What are the The UMIK-1 THD figures? Is that factored in the caibration file from MiniDSP? Checking that out now too. My MC2 amp is sub 0.008% at these power levels. Also have a Neurochrome amp spare, I hope.
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Not sure what the advantages would be measuring that close at that level. The important thing is that the distortion levels are higher than the noise floor at the microphone, I'm guessing that won't be an issue at 1 m or even 2 m. When you find your preferred method, I will duplicate it and measure my own system the same way for comparison.
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You will most likely clip the UMIK measuring that loud that close. In standard gain setting 112dB is the maximum. There is a switch inside where you can set it up with -18dB making the maximum spl 130dB.
104dB at 1m is 124dB at 10cm, that is pushing a Umik in low gain mode.
If you want to do that sort of testing then get a calibrated analogue mic and a preamp. I don't regret buying my Sonarworks Xref20 mic as it was pretty cheap from Thomann, but I already had a reasonable interface with a mic preamp.
Listen to your speaker with the 2k dip left alone and then boosted flat to see if you can tell the difference and which one you prefer. That is clearly an acoustic issue in the HF10AK, sometimes they are just best left alone unless you fix it acoustically.
I'd try just cranking the level at crossover to match woofer and use cuts instead of boost. You'd be down to two minor EQ's then @2180, 9300hz
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I use the HF10AK crossed at 1300Hz LR4 on the B52 horn for PA and play it loud. Sounds wonderful, and yes - the FR dip and distortion hump at 2K is there when I measure. It is much more offensive to the eye than to the ear. When I couldn't fix it using EQ I just told myself that the dip is an acoustically integrated "midrange compensation" and the 2nd order distortion is "euphonic enhancement." Now I sleep better at night.
Been away a while... still tinkering! Spawned a pair. Working on the second design of rear enclosure and also the Xover. More to follow!
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I love the look of horns built into the baffle instead of screwed on. Can you say how you machined the horns? I assume a CNC was used. I this a design you are open to share?
Thank you,
Duane
Hi Duane,
There is a pic in the first post showing the MDF on the CNC machine. Hope that helps!
Hi!
13 months later ...
I'm on version 2 of the cabs now along with hopefully the 3rd and final opamp based active crossover.
The rear cab panel will include a 1.25" shallow exponential port as previously suggested by @LineSource.
The stands / bass box will each house a pair of a opposing 15P80nd.
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Change of 4 resistors (double R5,6,7,8) produces an active 418-LR4 with a measured LR4 of 800Hz. See pic below.
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I've been trying out new filter arragement today and cranked to 102dB/1m. All charts are on axis except for the last - that is 45deg off.
Input PEQ
30Hz 12dB/oct High Pass
Crossover yields 24db/oct slopes at 850Hz
12p80nd 1250Hz Butterworth 24dB/oct, gain = 0dB
HF10AK 870Hz Butterworth 12dB/oct, gain = -7dB
12P80ND
80Hz Shelving Low Pass 9dB 12dB/oct
180Hz Shelving Low Pass 12dB 12dB/oct
1650Hz PEQ -7dB Q2.0
HF10AK
2070Hz PEQ +5dB Q4.5
9100Hz PEQ +3dB Q2.2
1050Hz PEQ +1dB Q1.0
Input PEQ
30Hz 12dB/oct High Pass
Crossover yields 24db/oct slopes at 850Hz
12p80nd 1250Hz Butterworth 24dB/oct, gain = 0dB
HF10AK 870Hz Butterworth 12dB/oct, gain = -7dB
12P80ND
80Hz Shelving Low Pass 9dB 12dB/oct
180Hz Shelving Low Pass 12dB 12dB/oct
1650Hz PEQ -7dB Q2.0
HF10AK
2070Hz PEQ +5dB Q4.5
9100Hz PEQ +3dB Q2.2
1050Hz PEQ +1dB Q1.0
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Tomorrow I will try an impedance sweep of the drivers and also test the 12p80nd at the dust cap with various cabinet stuffing densities.
