MTRX and JBL 708i/Crown DCi

[Mishabou]

Hi there,

I'm using a DCi 8/300DA to power a 5.1 monitor system, 3 x JBL 708i and 2 x JBL 705i, the sub is active an JBL LSR6312. My interface is a DAD AX32 (same as MTRX) with Pro Mon option.

For calibration to film specs, i need to attenuate -20 dB. I can either do it on the interface DAD AX32 (via Pro Mon) or on the Crown amp. Does it make a difference ? If i chose to attenuate on the Crown, is this done pre or post DA, in other words, the attenuation is done in the digital or analog domain ?

Thanks

[Top Jimmy]

I didn't know the DA series DCi had analog attenuators. I know the N series does, I've configured and used many dozens via Audio Architect, but I rarely have used the analog. I'm always using BLU-Link. If there are no analog attenuators, then the DSP is the only place on the amp to do it.

It seems to me that since you can adjust either end of the signal path arbitrarity, I would decide what "knob position" at the Pro Mon you want to reflect as your standard SPL level and then attenuate at the amp to achieve the desired SPL.

[Mishabou]

Just talked to an engineer at Harman. He suggested attenuating on the DAD AX32 as it uses 64 bit floating vs 40 bit on the Crown. Both are done in the DSP domain.

[Farhoof]

But isn't it transported via Dante at 24bit so you will loose the benefit of the 64bit dsp?
I'd do it in the Crown, 40 bit is plenty. Unless you have a lot of processing going on in the DAD and the -20dB saves you from going over 0dBFS.

[Mishabou]

If i understand correctly, DAD uses 64 bit floating point DSP, so the attenuation will be done at 64 before it hits the Dante network.

As you mentioned Dante operating at 24 bit, i guess there is some sort of dithering going on between each ''stage'', DAD DSP to Dante to Crown which is 40 bits.

One big advantage i see in attenuating on the Crown is monitor protection. While i was setting up the DAD mon control i forgot to set the attenuation and had the volume quite high, nearly blew up my speakers.