Wireless transmission frequencies (microphone)-help me out?

[Driller]

I'm looking at hand wireless held mics (and transmitter systems for in ear monitors) but the specifications seem very confusing.

They talk about:

1) Bandwidth in KHz
2) Frequency in MHz
3) Band eg A, B, C, D, E etc
4) Channel. They mention channels 69, 70 and the latest in the UK being 38.

Could a kind soul explain all this simply?

I've been looking at systems from Sennheiser as I use a wired E945 and it's great.

(Mods, I wasn't sure whether to put this in Music or Science-if it doesn't get any luck could we move it? Thanks.)

[Mr Pointy]

Driller said:

I'm looking at hand wireless held mics (and transmitter systems for in ear monitors) but the specifications seem very confusing.

They talk about:

1) Bandwidth in KHz
2) Frequency in MHz
3) Band eg A, B, C, D, E etc
4) Channel. They mention channels 69, 70 and the latest in the UK being 38.

Could a kind soul explain all this simply?

I've been looking at systems from Sennheiser as I use a wired E945 and it's great.

(Mods, I wasn't sure whether to put this in Music or Science-if it doesn't get any luck could we move it? Thanks.)

Bandwidth refers to the bandwidth of the transmitted RF signal, the maximum is 200kHz. As the spectrum is divided up into slots if a transmitter had too high a bandwidth it would interfere with the frequency slots on either side.

Frequency is the spot frequency of the transmitter output. These are specified & managed so that transmitters in the same location don't interfere

Band A-E refers the range of frequencies a particular unit can cover. The total permitted frequency range is too large to be covered by a single TX or RX board so it is subdivided down into smaller ranges.

Channels refer to (originally) TV broadcast channels & is simply a block of frequencies in the UHF spectrum. They were originally divided up so that adjacent TV transmitters were on different frequencies & so didn't interfere with each other. Some of these channels/frequency blocks were reserved for uses such as radio mics so that a radio mic could be used anywhere in the country without interference from the TV broadcasts. Channel 69 was one such block, but it was withdrawn (I think to sell off for mobile phone use) & all the owners of radio mic kit had to buy new stuff. Watch out for second hand kit that uses this channel - it's illegal to use.

There are now two channels for radio mics: 38 & 70. Channel 70 is general use & unlicenced which means you have no guarantee someone nearby isn't going to have a transmitter on the same channel. Channel 38 is licenced, but sometimes also by location so you don't interfere with other users at the same site.

So you could get away with an unlicenced channel 70 radio mic BUT I don't think the same applies to the IEM. From my reading I don't think there is an unlicenced IEM channel, but I may be wrong.

Some useful links - note not all are completely up to date with the channel 69 situation:

https://www.pmse.co.uk/licences.aspx
http://www.pmse.co.uk/pmse-spectrum.aspx
http://www.canford.co.uk/Technical/Article/Channel...
This one includes information about Bands A-E
http://www.gbaudio.co.uk/radio.htm

Edited by Mr Pointy on Sunday 7th September 12:16

[Mr Pointy]

Just to add that there are a number of slots within channel 70, it's not like you can only have one TX at a site. The transmitters are pre-programmed with a number of different spot frequencies.

Also looking at the Sennheiser website the IEM systems do seem to be available in the unregulated Channel 70 range.

[Driller]

Wow, thanks for all that valuable info, you know your stuff!

I'm still not sure about the difference between "channel" and "band" though.

On one of those links you kindly gave me it says that channel 38 is 606-614 (MHz?) but this chart says this is also called "GB":


European wireless microphone manufacturers' UHF frequency range options:

Range A = 516 - 558 MHz (includes frequencies in TV channels 26 to 31)

Range G = 566 - 608 MHz (includes frequencies in TV channels 33 to 37 and a bit of 38)

Range GB = 606 - 648 MHz (includes frequencies in TV channels 38 to 42)

Range B = 626 - 668 MHz (includes frequencies in TV channels 40 to 45)

Range C = 734 - 776 MHz (includes frequencies in TV channels 54 to 59)

Range D = 780 - 822 MHz (includes frequencies in TV channels 59 to 64)

Range E = 823 - 865 MHz (includes frequencies in TV channels 65 to 70)

And range "E" includes channels 65-70

So why do we talk about transmitters only doing channels 38 and 70 (and not 69!) when you can buy brand new transmitters that cover all these channels?

(I think I'm being dim clearly).

[Mr Pointy]

No, you're not being dim, I left out a bit of the gory detail out.

While channels 38 & 70 are reserved for radio mic use it doesn't mean that the rest of the spectrum is unavailable, it just requires very careful management to avoid interference. If you have mics in channels 38 or 70 you can use them anywhere in the UK (more or less) without interference from the TV system. This is obviously of great benefit for hire companies or those who need to use kit around the country. However, as there are only four available slots in channel 70 & about 10-12 in channel 38 it would be impossible to put on large productions if only frequencies in channels 38 & 70 could be used.

This is where the Joint Frequency Management Group come into play. They can issue a license for pretty much any frequency, but it's dependent on the location the equipment is to be used. When you apply for a license you tell them the equipment, the power, the building construction & the postcode & they can work out which frequencies are available in that area. This licence is non-mobile though, so you cannot use those frequencies anywhere else, possibly not even in the next building. You can imagine if all the West End theatres were in the same band you'd have mayhem. These licences can be for long term, say for a theatre or a TV studio, or just for one event, like the Olympics or the F1 weekend at Silverstone. This is the planning document for Silverstone:

http://www.pmse.co.uk/media/815/British_Grand_Prix...

So this is why equipment is available outside of channels 38 & 70. If you're a travelling minstrel you are probably stuck with these two though - plus the VHF allocation, although it's not so popular now.

[Driller]

Ok that's clear now, thanks.

Two bits of info I didn't include is that this will be for use in and around Paris and it's for gigs in a rock band so the location will change (a bit).

I know the rules are a bit different for Europe and that normally no licence is required. I believe that channel 38 is not available here but 70 is.

What do you do for a living out of interest?

ETA I mean, I assume it's linked to this!

Edited by Driller on Sunday 7th September 20:28

[Mr Pointy]

Ah, can't help you too much them I'm afraid. Sennheiser have an International Frequency Advisor:

http://en-uk.sennheiser.com/service-support-sifa

But it seems it cannot cope with the anarchic French & they aren't listed.

The French office is here & they should be able to advise you:
http://fr-fr.sennheiser.com/dun-coup-doeil-contact...

My schoolboy French doesn't cover the technical details of wireless mics I'm afraid. All I needed was deux bierre svp.

In real life I build various types of broadcast installations. I don't do stuff like detailed RF planning but I do organise for an outside company to do it when needed as part of an overall installation.

[Le TVR]

The problem came from the EU directive that attributed 789 - 866 MHz to 4G applications.
The only legal response to the question must come from ARCEP, probably on their espectre website.

A good analysis from AT:

http://eu.audio-technica.com/fr/support/FAQ_France...

[Jazzy Jefferson]

Driller said:

I'm looking at hand wireless held mics (and transmitter systems for in ear monitors) but the specifications seem very confusing.

They talk about:

1) Bandwidth in KHz
2) Frequency in MHz
3) Band eg A, B, C, D, E etc
4) Channel. They mention channels 69, 70 and the latest in the UK being 38.

Could a kind soul explain all this simply?

I've been looking at systems from Sennheiser as I use a wired E945 and it's great.

(Mods, I wasn't sure whether to put this in Music or Science-if it doesn't get any luck could we move it? Thanks.)

I sell Sennheiser and other wireless equipment for a living.

The simplest way to look at is... How many wireless system are you intending on running? If its more than 3 or 4, you need to worry about channels and frequencies.

If it's no more than 3-4 systems, get Band E, or Channel 70 systems. These are licence free.

[Driller]

Mr Pointy said:

Ah, can't help you too much them I'm afraid.

Well you've helped massively already, thanks very much!

Le TVR said:

The problem came from the EU directive that attributed 789 - 866 MHz to 4G applications.
The only legal response to the question must come from ARCEP, probably on their espectre website.

A good analysis from AT:

http://eu.audio-technica.com/fr/support/FAQ_France...

Great link, thanks for that. Why do the Frogs have to do things so differently to everyone else?

Jazzy Jefferson said:

I sell Sennheiser and other wireless equipment for a living.

Made me laugh, you came along just like Roger The Shrubber Glad you did though :-)

Jazzy Jefferson said:

The simplest way to look at is... How many wireless system are you intending on running? If its more than 3 or 4, you need to worry about channels and frequencies.

If it's no more than 3-4 systems, get Band E, or Channel 70 systems. These are licence free.

I need a system with 1 mic (I use an E945 so thought it would be nice to have this. I would use a condenser version but it's heavy rock and I'm worried it would be too sensitive) and an IEM system for my in ears.

Don't think they do a system that does both.

As you're a specialist though I'd love to know the practical differences between the ew 100 vs 300 vs 500. Not clear at all on the website. I can put in whatever money it takes but I don't want to waste anything on features I won't use.

Out of interest do bands A-D not work in the UK?

Edited by Driller on Wednesday 10th September 13:54

[Jazzy Jefferson]

Driller said:

I need a system with 1 mic (I use an E945 so thought it would be nice to have this. I would use a condenser version but it's heavy rock and I'm worried it would be too sensitive) and an IEM system for my in ears.

Don't think they do a system that does both.

As you're a specialist though I'd love to know the practical differences between the ew 100 vs 300 vs 500. Not clear at all on the website. I can put in whatever money it takes but I don't want to waste anything on features I won't use.

Out of interest do bands A-D not work in the UK?

Edited by Driller on Wednesday 10th September 13:54

Yes, Shrubberies are my trade. I arrange, design, and sell shrubberies.

945 is a good shout. As you say, condensers can be a bit lively. Alhtough, not impossible to work with.

If you need an IEM and a mic, then stick with channel 70 systems, keeps it easy from a licencing point of view. Sadly, wireless mics work on a "per mic" basis, so you need a full mic system, and an IEM system. You're right, there isn't a system that does both.

In simple terms, going up to a higher model allows you to use a greater number of systems. So if you wanted to have 20+ wireless mics, you would need a 500 series. As anything below this, does not have the range to program or allow this. You get better mics on the 500 series. 100 and 300 are the same as one another.

For us more normal folk who don't use such numbers, the 100 series is absolutely fine.

However, the 300 series (iirc) has metal bodies and chassis, which of course means greater durability, and they also ship with rack mounting kits, so easier to mount/transport. As well as the ability to use a greater number of systems. There's a few other small things like a headphone output, and other things I cannot recall.

Sennheiser IEM systems are only available within the ew300 series and up, so you'd have to get that. To match it, an EW345 system would be great. However you could save a few quid and go for the EW145 system instead?

The other bands will work in the UK, however it may be illegal to use them, or you might find something else is already transmitting on them.

Hope that helps.

Edited by Jazzy Jefferson on Thursday 11th September 11:59

[Driller]

Jazzy Jefferson said:

Yes, Shrubberies are my trade. I arrange, design, and sell shrubberies.

Jazzy Jefferson said:

945 is a good shout. As you say, condensers can be a bit lively. Alhtough, not impossible to work with.

If you need an IEM and a mic, then stick with channel 70 systems, keeps it easy from a licencing point of view. Sadly, wireless mics work on a "per mic" basis, so you need a full mic system, and an IEM system. You're right, there isn't a system that does both.

In simple terms, going up to a higher model allows you to use a greater number of systems. So if you wanted to have 20+ wireless mics, you would need a 500 series. As anything below this, does not have the range to program or allow this. You get better mics on the 500 series. 100 and 300 are the same as one another.

For us more normal folk who don't use such numbers, the 100 series is absolutely fine.

However, the 300 series (iirc) has metal bodies and chassis, which of course means greater durability, and they also ship with rack mounting kits, so easier to mount/transport. As well as the ability to use a greater number of systems. There's a few other small things like a headphone output, and other things I cannot recall.

Sennheiser IEM systems are only available within the ew300 series and up, so you'd have to get that. To match it, an EW345 system would be great. However you could save a few quid and go for the EW145 system instead?

The other bands will work in the UK, however it may be illegal to use them, or you might find something else is already transmitting on them.

Hope that helps.

Edited by Jazzy Jefferson on Thursday 11th September 11:59

Certainly does, that's brilliant thanks. I was going to buy through Thomann, what sort of set up does your company have, do you sell to the general public in limited quantities? ie one of each

[Jazzy Jefferson]

Driller said:

I was going to buy through Thomann

You had me up until that point.
Ask your friendly UK retailer to price match, that way guys like me stay in business and can then help you on forums and what not

The company I work for sell to the general public, however I cannot really advertise here. If you needed "Spares" for your "Studio" in North London, you might call us.

[IainT]

Jazzy Jefferson said:

Driller said:

I was going to buy through Thomann

You had me up until that point.

I try to support local retailers but I'm in the market for an Avid Eleven Rack at the moment and they're well £150 cheaper than the best in the UK. Line 6 POD HD Pro is the other contender and they're close to the same price everywhere.

My regular bass dealer tries to price match them and GAK but sheer size makes it impossible. In his case, I'm happy to pay a premium for great service but for something he doesn't deal in price wins.

[Jazzy Jefferson]

IainT said:

I try to support local retailers but I'm in the market for an Avid Eleven Rack at the moment and they're well £150 cheaper than the best in the UK. Line 6 POD HD Pro is the other contender and they're close to the same price everywhere.

My regular bass dealer tries to price match them and GAK but sheer size makes it impossible. In his case, I'm happy to pay a premium for great service but for something he doesn't deal in price wins.

Well we can't win them all. But I am surprised no UK dealer can match their price...? They should be able to. They're not trying

Edited by Jazzy Jefferson on Tuesday 16th September 09:46