Wireless Nightmares

[Mike_Bax]

Hi, me again

I am having a wireless nightmare

In our band, we use the following

Sennheiser Freeport Wireless Vocal Mic 863.100MHz
AKG WMS 40 Pro Guitar Pack 864.375MHz
Thomann T-Bone IEM100 864.900MHz

Now, although the Thomann isn't the best brand, I don't think this is causing the issue, as along side the Sennheiser Mic, we can play, trouble free.

Now, as soon as I use my AKG WMS Pro40, "fart noises" come through our singers monitor, which, I can only put down to frequency cross modulation with the Sennheiser unit.

I would have thought a difference of 1.275MHz would have been ample.

Would appreciate any help people could give me.

[Hugh Robjohns]

The channel spacing is not the only thing that matters. The way the harmonics of different TX frequencies from each transmitter line up across the spectrum is also vitally important.

A quick check of frequencies suggests that these should all play nicely together, although that will depend to an extent on how clean each TX is and how good the filtering is in the RXs.

It might also be that the AKG is a higher powered TX and causing overloads in the Sennheiser receiver.

H

[Mike_Bax]

I will see it the transmitter pack on the AKG can be turned down, worth a try.

Thank You

[Mike Stranks]

... and it sometimes helps to put some physical distance between receivers too - especially when you're using kit from different manufacturers. Rack-mounting and stacking isn't all it's cracked-up to be!

[Mike_Bax]

I generally try to do this, the transmitter for the Thomann is mounted in the FX rack, the Sennheiser receiver is generally on the floor near the stage box, and the receiver for the AKG Guitar pack is on top of my amp.

The AKG has a fixed frequency, but the Sennheiser has 4 channels, and the Thomann 16. Maybe I should just experiment with different channels on these two, see what happens.

These experiments will be carried out at the rehearsak room.

[TSH-Tim]

100% we had a load of ULX racked up together until we started to see huge RF spikes ! Moved the units apart - problem solved

[Mike_Bax]

I always try to play (guitar, with the AKG WMS40) on the opposite side of the stage to the Sennheiser Freeport receiver. So usually at leat 10 to 15 feet away from the unit, and of course, our singer, with the Freeport Mic is generally closer to the Sennheiser receiver than I am.
We always use new batteries for every performance, so low strength signal shouldn't be an issue.