Hi Guys.

I work in a school who use a small radio mic setup (4x Sennheiser freeports).

I've been asked to look into expanding the setup to 8 total.

Im a bit stuck as to how the digital sell off is going to affect my existing setup and any new ones I'm looking to purchase.

As a test I have picked up an Audio Technica 700 Series system which can run up to 8 channels.

Im looking at the manual which says the TV channels it runs on are 62, 63, 64, 69 and 70. I know my existing Sennheisers are also using the same channels so I can add 4 of these to make my 8... but...

are all of these channels going to disappear after the sell off? Im finding masses of conflicting info on the interweb and neither manufacturers or retailers seem interested in answering my questions.

many many thanks for your help guys,

Remo

I'd suggest talking to Sennheiser UK and discuss with them your current system and your future requirements. The new free-access channels are going to get horribly congested and your best bet is going to be to buy location-specific licences to use the interleaved spectrum between TV channels. But as to which channels are available to you -- and which channels your Freeports can be tuned to -- will depend on where you are.

Sennheiser UK are fully aware of what can and can be done, and I'm sure they'd welcome your business of buying another four channels, so give them a call.

Hugh

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Technical Editor, Sound On Sound

The manual for your Freeports should tell you which frequencies they operate on. I suspect they'll be between 863.1 and 864.9, which is the licence-free part of ch.70. Without getting a licence (currently £75 / year), that's as much as you can operate. Your new AT system unfortunately won't be of much use to you as you won't be able to use ch.69 and below because of the digital switchover and you're already using all you can in ch.70.

To use more than four system, you'll need to look at ch.38 systems, which do need a licence. There are a couple of digital systems out there now that can be operated without a licence (Line6 is the cheapest option - they are remarkably good) which is another option you can look at.

I would certainly back up Hugh's advice of talking to someone who knows what they're talking about. Not all shops do...

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There's nothing we can't face... Except for bunnies

Just to confirm...

Freeport is all Channel 70 (863.1-864.9) and the max number of Freeport sets you can run in that channel is four.

Mr Willett will doubtless be along shortly, but FWIW I think a set of Channel 38 mics will be needed. Something like this????

Trantec 4.16 Rackpac

(Available in a rack of four sets)

... just remembered that John Willett's been mentioning the new Sennheiser XSW line... maybe those are a possibility...

Edited by Mike Stranks (28/02/12 11:14 AM)

as mentioned, you can use CH70 free of charge/licence free and normally get 4 frequencies in that channel.

The current paid JFMG licence enables you to use ch69 and ch38, with geographic exceptions (not everywhere is ch38 compatible; when this occurs JFMG can advise on certain frequencies in CH39 and CH40).

As Hugh mentioned ch70 is going to get seriously congested, with who-knows what interference from 4G transmitters. Initial patents on transmitters fit into their designated bands, but if you look at what a iphone radiates compared with its patents.. Quite alarming.

To ensure you have a 8 channel system that will work past 2012, you need to get units that are CH38 compatible, AND A LICENSE!!!

If everyone had a license, we might not be in this situation at the moment!

Quote Peter Dakin:

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If everyone had a license, we might not be in this situation at the moment!

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Ain't that the truth!

hugh

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Technical Editor, Sound On Sound

You already have the maximum number of FreePORT systems you can - you cannot add anything in channel 70.

Channels 60-69 are part of the sell-off for G4 mobile broadband.

This is very likely to seriously interfere with the Ch.70 licence-free frequencies that FreePORT are on.

My advise would be to get rid oof the FreePORTs and get a new 8-channnel system on new frequencies.

The best option for a school is to get a system on fixed site co-ordinated frequencies on channel 39, 40 or 41. This will keep you clear of the Ch.38 frequencies that all the mobile stuff will use. Only get Ch.38 frequencies if you plan to use the system in different locations.

Talk to JFMG to find out what frequencies you can licence on a co-ordinated basis at your site.

If you want to keep the price down, you could look at the new Sennheiser XS Series - this is very affordable and about half the price of evolution G3 and, I think, available for less than £300 a set.





For best results you really should use a single pair of antennas and antenna splitters.

I hope this helps.

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John - Sound-Link ProAudio
President - Federation Internationale des Chasseurs de Sons

Thanks John... informed, helpful and precise as always.