Interfacing the MixPre or 302 with a Shure FP33

Sound Devices MixPre and the Shure FP33 mixer can be interconnected to combine inputs. An interconnected MixPre and FP33 combination results in the following:

• a 5 X 2 mixer, with limiters on the MixPre's inputs
• 48 volt phantom power for all five microphone inputs
• pan switches on MixPre inputs, pan pots on FP33 inputs
• two output buses, assignable to mic or line level output

The combination of the MixPre and an FP33 (or FP32A) is a cost-effective, multiple-input, field mixing setup. The MixPre's compact size (less than half the size and weight of the FP33) adds little bulk to an existing FP33 package. A Sound Devices MP-2 can also be used with the FP33 in the same manner as the MixPre. The MixPre/FP33 combination can accept a stereo microphone, hard-wired shotgun, and two RF lavs simultaneously.

Early Model MixPre and MP-2

A cable assembly wired as below is required to properly interconnect the balanced, line level XLR outputs of the MixPre (or MP-2) to the mix bus of the FP33. Note that this is the interconnection for impedance-balanced MixPre's (sn <0507).

With the above interconnection, all five inputs appear at the FP33 master section. Please note the following conditions.

• MixPre inputs are reverse polarity with respect to FP33 inputs. Since the mix bus on the FP33 is inverting one must connect to pin-2 of MixPre or MP-2. (NOTE: For MixPre with S/N 0507 or greater, connect to pin-3 and float pin-2. No polarity inversion will occur.)
• Cable length should be kept to a practical minimum, since the interconnection is unbalanced.
• Headphone monitoring is done at the FP33.
• The MixPre (and MP-2) have isolated external DC input jacks so there are no ground related interference problems when interconnecting the MixPre and an FP33, no matter the power sources used.

Late Model MixPre and 302

To interface active-balanced MixPre (s/n >0507) or 302 outputs to the FP33 mix bus, a unique cable is required.

• MixPre and 302 inputs are in proper polarity with respect to FP33 inputs.
• Cable length should be kept to a practical minimum, since the interconnection is unbalanced.
• Headphone monitoring is done at the FP33.
• The MixPre amd 302 have isolated external DC input jacks so there are no ground related interference problems when interconnecting to the FP33, no matter the power sources used.

If you have any questions about this modification, please contact Sound Devices or Shure's Applications Group.