Need a line-level wireless transmitter

[MichaelPatrick]

Originally Posted by fifthcircle

There's a hall with no lines from the FOH position to stage? That's really odd.

It's an old historic building made of stone. All the mics are wireless.

[karlw]

Originally Posted by Rolo 46

Lectros are heavy on batteries and have high op power
A very selective and sensitive RX is better
Especially with multi radio systems where TX power must be lower.

This is kind of an old view, frankly. Shure, Sennheiser and Lectrosonics all make selectable-power transmitters now. With the RF background noise floor rising, there are many times with higher TX RF power is desirable. Of course it is important to watch for increased IM as well. In the case of Lectrosonics, the transmitters have long had isolated outputs which cuts down greatly on TX-TX intermods. There are hundreds of high-channel count Lectrosonics systems in use for TV & theater productions today.

[John Willett]

Originally Posted by karlw

This is kind of an old view, frankly. Shure, Sennheiser and Lectrosonics all make selectable-power transmitters now. With the RF background noise floor rising, there are many times with higher TX RF power is desirable. Of course it is important to watch for increased IM as well. In the case of Lectrosonics, the transmitters have long had isolated outputs which cuts down greatly on TX-TX intermods. There are hundreds of high-channel count Lectrosonics systems in use for TV & theater productions today.

Careful - high output power is illegal in most countries without special and expensive licenses.

The US has a radiomic. spec. that is illegal in most other places - so something made specifically for the US market will be illegal elsewhere.

The international spec. is 50mW max. for a transmitter, body worn - this can reduce to 10mW for a hand-held device (this is e.r.p., of course, measured on a dipole antenna at 1m).

For multi-channel use, lower output power is normally better as the spurious emissions are much lower.

High power is normally only needed for range and in cases where very few transmitters are used together.

[MichaelPatrick]

fwiw, I'm looking at these:

Lectrosonics HB transmitter and UCR401a receiver.
Sennheiser SKP2000 transmitter and EK2000 receiver.

[karlw]

Originally Posted by John Willett

Careful - high output power is illegal in most countries without special and expensive licenses.

The US has a radiomic. spec. that is illegal in most other places - so something made specifically for the US market will be illegal elsewhere.

It is probably important for readers to know this. However, Lectrosonics (and other brands) typically only sell legal systems in the respective countries/territories. Even still, most manufacturers now offer selectable transmission power.

The international spec. is 50mW max. for a transmitter, body worn - this can reduce to 10mW for a hand-held device (this is e.r.p., of course, measured on a dipole antenna at 1m).

International spec? There is no such thing. Each country has their own laws. In the US, UHF transmitters can (with a part 74 license) be used up to 250 mW. In Australia, <100 mW can be used - literally - 99 mW. In the EU it is 50 mW. In Japan, it is 10 mW.

For multi-channel use, lower output power is normally better as the spurious emissions are much lower.

High power is normally only needed for range and in cases where very few transmitters are used together.

The view on this is changing, John. With a rising RF noise floor, power can be helpful, whether it is for just a few channels or many. Talk to some of the guys that do large events like Dave Bellamy at Soundtronics in LA. He does the Grammies, American Idol, etc. He has told me, without my prompting, that they routinely use the higher power settings on transmitters now. With proper frequency coordination and good equipment, they achieve success with this approach.

"All things being equal", yes, lower TX power may be better for multi-channel systems. However, all things are not equal. Different companies put their design emphasis in different areas. Each has their dominant market areas, and each achieves a high degree of success in those areas - with everything from 1 channel to 100+.