I want to use both the on-camera mic and a Sennheiser wireless in a four channel HDV configuration (yes, I know the bandwidth of each channel is halved, but I'm just recording voice interviews and crowd noise). I'm confused by the 1/3 and 2/4 XLR inputs. Why isn't this 1/2 and 3/4? The Sennheiser ew100 receiver has an XL cable that I attached to XLR 2/4. How do I record the Sennheiser to channels 3/4 in stereo?

Best,
Christopher

I've tried the same configuration as you, but don't use it anymore since it's a bit complicate to acquire the 4 channels in Final Cut Pro.
Anyway, for recording, put AUDIO 1 on Front Mic and Audio 2 on REAR. Then plug your Sennheiser's XLR on Channel2/4 (this input should be on "line in" and not "mic" I guess), level on manual and adjust it (position 10 o'clock for me).
In this configuration, you'll have 3 channels : Front Mic left, Front Mic right and mono Sennheiser on channel 4 (it's not a stereophonic microphone).

In order to keep a better sound resolution, I'm using now a mono microphone (AT 897) for ambiant on XLR 1/3 and the wireless Sennheiser on XLR 2/4. In FCP I obtain the ambiant on the left channel and the interview on the right one, so I have to remix it in bi-mono.

Hope this help...

(it's not a stereophonic microphone)

Silly me, each XLR is mono. That means the 1/3 and 2/4 will accept either channels 1 and 2 or 3 and 4. Thanks, it makes sense now.

Best,
Christopher

and the wireless Sennheiser on XLR 2/4.

When using the wireless Sennheiser with XLR, does it make any difference if the phantom power is on or off?

Best,
Christopher

Don't use the 48V with the Sennheiser! It has its own batteries and might don't appreciate more power...
You have to turn on the Mic att, on the channel 2/4 by the way.