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JTR Triple 12 and Orbit Shifter

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Jeff Permanian:
Evan Kirkendall wrote on Sat, 08 January 2011 19:32

The Triple 12 seems to roll off fast about 8k, and has a weird dip around 300hz, but is otherwise pretty flat. I ended up using 4 EQ filters total.

EQ1: -3 @ 560hz, Q3
EQ2: -2 @ 5k, Q4
EQ3: -3 @ 8k, Q6
EQ4: +4 @ 9k, Hi Shelf

Nothing too crazy. The box still seems to struggles past 12k, but it's not terrible.

Listening tests:

The cabinets do stay pretty clean and pretty smooth as you crank them up, but the HF struggles as you approach limit on the IT4000.

Evan


Evan

There is definitely something wrong with your measurements. The Triple 12X is flat to 20khz. That +4db shelf is causing you to reach the compression drivers limits early. I would remove that filter immediately. By the way, the 2011 models now come with a BMS compression driver.

Also, I'm in the process of making grills for the Orbit Shifter.

Jeff

Jon Waller:
Jeff Permanian wrote on Mon, 10 January 2011 10:17
Evan Kirkendall wrote on Sat, 08 January 2011 19:32

The Triple 12 seems to roll off fast about 8k ...
Evan


Evan

There is definitely something wrong with your measurements. The Triple 12X is flat to 20khz...

Jeff



Judging by the pictures, I would guess the microphone is far enough off axis from the coaxial driver on top to be out of the VHF pattern.  Coaxial drivers like that are quite beamy above 8kHz!

Evan Kirkendall:
Jeff,
I measured the horn on axis @ 1m, and ground plane at 1 & 2m. The measurements were all consistent. It's not the mic, as it showed the EV and Mackie boxes flatter out to 16k.


Robert,
The only time the amp affected the sound was when it shut down due to low voltage.





Evan

TrevorMilburn:
Quote:
 
The cabinets do stay pretty clean and pretty smooth as you crank them up, but the HF struggles as you approach limit on the IT4000.


I haven't used SMAART myself, so I am not conversant with the displays shown (I saw the 0dB in the display), but were the measurements taken at full power on the IT4000 or at 1w or some other power? I say this because the speakers IIRC are rated at 1600w program which means that if they were being given the full 2000w the IT4000 is capable of at 4ohms and had a 4db HF eq boost applied, the HF would be pushed well beyond it's comfort zone. I would expect most lesser speakers to be screaming for mercy or completely giving up the fight. Also, is it possible that the coaxial MF/HF was mounted in the centre position (it is a sealed unit so can be moved quite easily from what I have read elsewhere) and the measurements were inadvertently not taken on axis at all?
Just curious.

Regards,
Trevor

George Friedman-Jimenez:
Evan Kirkendall wrote on Mon, 10 January 2011 13:26
Jeff,
I measured the horn on axis @ 1m, and ground plane at 1 & 2m.
Evan


Following up on Jon's and Trevor's suggestions, when you did the ground plane measurements, how many degrees off the axis of the coax CD was the mic when at 1m and when at 2m?

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