[[email protected]]

I have been having trouble with interference on Shure UHF microphones.
I typically use bewtween 8 and 15 in the same room. I've tried
antenna distributions with limited success. I've been advised to put
all the wireless on the same group, but I find that advise to be
suspect. The groups the mics have are a1, a2, 1,2,3,4,5,6,7. I think
the problem might be with the pda's and cell phones that clients
bring. If anyone has any advise or insight, it would be greatly
appreciated.
Thanks,
Steve

[Scott Dorsey]

wrote:
I have been having trouble with interference on Shure UHF microphones.
I typically use bewtween 8 and 15 in the same room. I've tried
antenna distributions with limited success. I've been advised to put
all the wireless on the same group, but I find that advise to be
suspect. The groups the mics have are a1, a2, 1,2,3,4,5,6,7. I think
the problem might be with the pda's and cell phones that clients
bring. If anyone has any advise or insight, it would be greatly
appreciated.

You have two issues: outside interference from other sources, and
inside interference from the various transmitter products mixing together.
You need to find channel assignments free of both.

GSM cellphones will cause interference issues with those wideband
receivers, and there's nothing much you can do about it, other than
to keep the receiver away from the cell users and use preselectors
or better receivers.

For the issues with the individual transmitters interfering with one another,
the Sennheiser website has a gadget where you can plug in your wireless
frequencies and figure out where the intercepts fall. You need to do
this in order to lay out a reasonable signal plan if you're going to be
using that many units together. In addition, you may want to do a sweep
with a spectrum analyzer or at least a cheap scanner and make sure all
the spaces are clear.

When you do the intercept math, get a list of a few more channels than
you will actually need, so you can relocate some units to deal with
outside interference.
--scott
--
"C'est un Nagra. C'est suisse, et tres, tres precis."

[Richard Crowley]

wrote ...
I have been having trouble with interference on Shure UHF microphones.
I typically use bewtween 8 and 15 in the same room. I've tried
antenna distributions with limited success. I've been advised to put
all the wireless on the same group, but I find that advise to be
suspect. The groups the mics have are a1, a2, 1,2,3,4,5,6,7. I think
the problem might be with the pda's and cell phones that clients
bring. If anyone has any advise or insight, it would be greatly
appreciated.

You will likely have to be more specific about exactly what
kind(s) of "interference" you are talking about. Both the
large number of adjacent wireless mic transmitters/receivers
AND the possibility of external interference (cell phones and
other 2-way gadgets like pagers, PDAs, etc.) could be
causing your "interference".

One piece of differential diagnosis could be to power up all
your mics with nobody present to see if the problem could
be mutual interference (as contrasted with interference from
audience gadgets).

Did you buy the wireless units from a local dealer who
might be able to help with frequency coordination, etc?
Frankly, I am surprised that you can get that many mics
to work together without doing some serious engineering
to cause them all play together nicely.

[Geoff]

Scott Dorsey wrote:

For the issues with the individual transmitters interfering with one
another, the Sennheiser website has a gadget where you can plug in
your wireless frequencies and figure out where the intercepts fall.


I hope you mean "intermods"

geoff

[Scott Dorsey]

In article ,
Geoff wrote:
Scott Dorsey wrote:

For the issues with the individual transmitters interfering with one
another, the Sennheiser website has a gadget where you can plug in
your wireless frequencies and figure out where the intercepts fall.

I hope you mean "intermods"

Intermodulation products, which you can think of as intercepts on a
nomograph if you're old enough to have done that stuff without a
calculator.
--scott
--
"C'est un Nagra. C'est suisse, et tres, tres precis."

[Raw-Tracks]

wrote:

I have been having trouble with interference on Shure UHF microphones.
I typically use bewtween 8 and 15 in the same room. I've tried
antenna distributions with limited success. I've been advised to put
all the wireless on the same group, but I find that advise to be
suspect. The groups the mics have are a1, a2, 1,2,3,4,5,6,7. I think
the problem might be with the pda's and cell phones that clients
bring. If anyone has any advise or insight, it would be greatly
appreciated.

Which Shure UHF wireless systems do you have. ULX, U, U-HR, SLX, UT,....
it would help to know which systems you are actually using.

--
Eric

Practice Your Mixing Skills
Download Our Multi-Track Masters
www.Raw-Tracks.com
www.Mad-Host.com

[Raw-Tracks]

Richard Crowley wrote:

Frankly, I am surprised that you can get that many mics
to work together without doing some serious engineering
to cause them all play together nicely.

With proper planning, it's really not that big of a chore to get than
many channels, and many more, to work together reliably. First, you need
to have invested in quality wireless systems. Then, it's just a matter
of applying proper methods to achieve good results.

--
Eric

Practice Your Mixing Skills
Download Our Multi-Track Masters
www.Raw-Tracks.com
www.Mad-Host.com

[Richard Crowley]

"Raw-Tracks" wrote...
Richard Crowley wrote:

Frankly, I am surprised that you can get that many mics
to work together without doing some serious engineering
to cause them all play together nicely.

With proper planning, it's really not that big of a chore to get than
many channels, and many more, to work together reliably.

Of course. But the wording of the question didn't sound
like it was a result of "proper planning". Did it to you?

[Raw-Tracks]

Richard Crowley wrote:
"Raw-Tracks" wrote...

Richard Crowley wrote:

Frankly, I am surprised that you can get that many mics
to work together without doing some serious engineering
to cause them all play together nicely.


With proper planning, it's really not that big of a chore to get than
many channels, and many more, to work together reliably.


Of course. But the wording of the question didn't sound
like it was a result of "proper planning". Did it to you?

My point is that your response makes it sound like it's quite difficult
to get that number of systems to work together. It doesn't take "serious
engineering", imo.


--
Eric

Practice Your Mixing Skills
Download Our Multi-Track Masters
www.Raw-Tracks.com
www.Mad-Host.com

[Richard Crowley]

"Raw-Tracks" wrote ...
My point is that your response makes it sound like it's quite
difficult to get that number of systems to work together. It doesn't
take "serious engineering", imo.

The people who actually do it seem to think that it does
require "proper planning". What is your experience
with multiple wireless mics?

[Richard Kuschel]

On Mar 1, 7:29 am, Raw-Tracks wrote:
Richard Crowley wrote:
"Raw-Tracks" wrote...

Richard Crowley wrote:

Frankly, I am surprised that you can get that many mics
to work together without doing some serious engineering
to cause them all play together nicely.

With proper planning, it's really not that big of a chore to get than
many channels, and many more, to work together reliably.

Of course. But the wording of the question didn't sound
like it was a result of "proper planning". Did it to you?

My point is that your response makes it sound like it's quite difficult
to get that number of systems to work together. It doesn't take "serious
engineering", imo.

--
Eric

Practice Your Mixing Skills
Download Our Multi-Track Masterswww.Raw-Tracks.comwww.Mad-Host.com

It requires a lot of planning and the equations can be quite involved
to get even 8 wireless microphones to work together properly.

If you add in a few outside sources of interference-cell phones, TV
stations, Business communications that might be in the area, it gets
damn complex and it is amazing that the low power wireless systems
work at all.

[Raw-Tracks]

Richard Crowley wrote:
"Raw-Tracks" wrote ...

My point is that your response makes it sound like it's quite
difficult to get that number of systems to work together. It doesn't
take "serious engineering", imo.

The people who actually do it seem to think that it does
require "proper planning". What is your experience
with multiple wireless mics?

My experience is that I regularly sell and support multi-channel systems
to many, many, churches, schools and universities, business and bands,
etc. Many of these clients are not too familiar with wireless
microphones and RF issues. It's rare that I ever have anyone calling me
with RF issues that can't easily be resolved.

Take a look at the Shure SLX system for instance. It's a relatively
inexpensive system, $5-600/channel. It couldn't be any easier to set up
multi-channel systems using SLX. All you have to do is turn off all of
your transmitters and turn on your first receiver. You then initiate the
scanning function on that first receiver. Once the scan is complete, it
will have a freq selected. You then turn on the transmitter and hold it
up to the receiver, press a button and the transmitter's freq is sync'd
via infra-red. Rinse, repeate.....on to the second....third...etc.

Shure also has a frequency utility on their web site that is very helpful.

Now, I'll agree that their still are unique situations that will require
major planning to get multiple wireless systems to work, especially when
you are attempting 20+ channels. With the proper equipment, the original
poster's problems really shouldn't be problems at all.

--
Eric

Practice Your Mixing Skills
Download Our Multi-Track Masters
www.Raw-Tracks.com
www.Mad-Host.com

[[email protected]]

Thanks for all your help guys.


On Mar 3, 9:13 pm, Raw-Tracks wrote:
Richard Crowley wrote:
"Raw-Tracks" wrote ...

My point is that your response makes it sound like it's quite
difficult to get that number of systems to work together. It doesn't
take "serious engineering", imo.

The people who actually do it seem to think that it does
require "proper planning". What is your experience
with multiple wireless mics?

My experience is that I regularly sell and support multi-channel systems
to many, many, churches, schools and universities, business and bands,
etc. Many of these clients are not too familiar with wireless
microphones and RF issues. It's rare that I ever have anyone calling me
with RF issues that can't easily be resolved.

Take a look at the Shure SLX system for instance. It's a relatively
inexpensive system, $5-600/channel. It couldn't be any easier to set up
multi-channel systems using SLX. All you have to do is turn off all of
your transmitters and turn on your first receiver. You then initiate the
scanning function on that first receiver. Once the scan is complete, it
will have a freq selected. You then turn on the transmitter and hold it
up to the receiver, press a button and the transmitter's freq is sync'd
via infra-red. Rinse, repeate.....on to the second....third...etc.
Thanks for all your help guys.


Shure also has a frequency utility on their web site that is very helpful.

Now, I'll agree that their still are unique situations that will require
major planning to get multiple wireless systems to work, especially when
you are attempting 20+ channels. With the proper equipment, the original
poster's problems really shouldn't be problems at all.

--
Eric

Practice Your Mixing Skills
Download Our Multi-Track Masterswww.Raw-Tracks.comwww.Mad-Host.com

[Raw-Tracks]

wrote:

Thanks for all your help guys.

Steve,

You never mentioned which wireless systems you are running. I'd be
curious to know.

--
Eric

Practice Your Mixing Skills
Download Our Multi-Track Masters
www.Raw-Tracks.com
www.Mad-Host.com