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Sound Reinforcement - Forums for Live Sound Professionals - Your Displayed Name Must Be Your Real Full Name To Post In The Live Sound Forums => Wireless and Communications => Topic started by: duane massey on January 05, 2017, 12:06:35 pm

Title: Help with large number of wirelss mics
Post by: duane massey on January 05, 2017, 12:06:35 pm
For those of you who have deal with musicals, etc where large quantities of wireless mics are used: do you use one antennae combiner system or is there a better or cheaper method? Thanks.
Title: Re: Help with large number of wirelss mics
Post by: William Schnake on January 05, 2017, 12:18:30 pm
For those of you who have deal with musicals, etc where large quantities of wireless mics are used: do you use one antennae combiner system or is there a better or cheaper method? Thanks.
Duane, we use anywhere from 16 to 28 wireless Shure ULX/p units for musicals.  I have mine setup with 4 ULX/P units in a rack with 1 UA844SWB per rack.  I have never had any problems with this setup.

Bill
Title: Re: Help with large number of wirelss mics
Post by: Scott Helmke on January 05, 2017, 12:29:40 pm
For those of you who have deal with musicals, etc where large quantities of wireless mics are used: do you use one antennae combiner system or is there a better or cheaper method? Thanks.

It depends on the exact situation, but we'll put 40+ channels on the same antennas using cascaded antenna splitters (usually Shure 845) as needed. That's with dual or quad receiver units that do their own internal distribution.

Using good quality antenna splitters is the better method.  Also it's usually cheaper than losing the gig because of wireless failures.
Title: Re: Help with large number of wirelss mics
Post by: Pete Erskine on January 05, 2017, 01:51:42 pm
For those of you who have deal with musicals, etc where large quantities of wireless mics are used: do you use one antennae combiner system or is there a better or cheaper method? Thanks.

I would advise you to not cascade more than once.  I did a show for the Chinese national orchestra.  2 antennas, Shure UA874, (1 on each side of the stage) feeding a Sennheiser AC3200 which is an 8 output combiner first and then a combination of more AC3200 and Shure UA845 5 output DAs.  We had a total of 70 channels as UHF-R half as ULX-1 with headsets and the other half ULX3 buttplugs with condenser mics.  It was flawless.

Control was all with Wireless workbench but coordination was with IAS.
Title: Re: Help with large number of wirelss mics
Post by: brian maddox on January 05, 2017, 03:22:36 pm
I would advise you to not cascade more than once.  I did a show for the Chinese national orchestra.  2 antennas, Shure UA874, (1 on each side of the stage) feeding a Sennheiser AC3200 which is an 8 output combiner first and then a combination of more AC3200 and Shure UA845 5 output DAs.  We had a total of 70 channels as UHF-R half as ULX-1 with headsets and the other half ULX3 buttplugs with condenser mics.  It was flawless.

Control was all with Wireless workbench but coordination was with IAS.

Pete i'm a little confused.  I thought the AC3200 was a transmitter combiner typically used with IEM transmitters.  Was it an ASA3000?  IIRC, That's the comparable Sennheiser antenna splitter.

And assuming it was, does that unit provide the necessary antenna power for those antennas?  If so that's a good thing to know...
Title: Re: Help with large number of wirelss mics
Post by: Neil White on January 05, 2017, 03:25:43 pm
I would advise you to not cascade more than once.  I did a show for the Chinese national orchestra.  2 antennas, Shure UA874, (1 on each side of the stage) feeding a Sennheiser AC3200 which is an 8 output combiner first and then a combination of more AC3200 and Shure UA845 5 output DAs. 

Hope you don't mind the correction Pete, but the 8 Way Senn. antenna distro is the ASA3000, the AC3200 is the 8 way TX combiner for IEMS.

A master distro feeding distro's in each rack is definitely the way to go for high channel counts, although does create a potential single point of failiure. If the show warrants high redundancy, I have previously used separate master antenna distro for each half of the diveristy antenna system.

A useful tip I have picked up for cascading units such as UR4D+ is to link through each side of the antenna system from opposite ends of the chain. I.E. start the A side at the top of the rack linking down and the B side from the bottom linking up. That way the loss of a unit in the chain only loses half the diversity for all the remaining units rather than a total loss of RF.
Title: Re: Help with large number of wirelss mics
Post by: brian maddox on January 05, 2017, 03:28:59 pm
Hope you don't mind the correction Pete, but the 8 Way Senn. antenna distro is the ASA3000, the AC3200 is the 8 way TX combiner for IEMS.

A master distro feeding distro's in each rack is definitely the way to go for high channel counts, although does create a potential single point of failiure. If the show warrants high redundancy, I have previously used separate master antenna distro for each half of the diveristy antenna system.

A useful tip I have picked up for cascading units such as UR4D+ is to link through each side of the antenna system from opposite ends of the chain. I.E. start the A side at the top of the rack linking down and the B side from the bottom linking up. That way the loss of a unit in the chain only loses half the diversity for all the remaining units rather than a total loss of RF.

Okay, now it looks like we're piling on....   ;)

Good tips in here.  Especially the cascade in both directions thing.  Clever.
Title: Re: Help with large number of wirelss mics
Post by: Pete Erskine on January 05, 2017, 05:51:51 pm
Pete i'm a little confused.  I thought the AC3200 was a transmitter combiner typically used with IEM transmitters.  Was it an ASA3000?  IIRC, That's the comparable Sennheiser antenna splitter.

And assuming it was, does that unit provide the necessary antenna power for those antennas?  If so that's a good thing to know...

Yes I gave the wrong number and the 3000 does supply antenna power suitable for Shure antennas.
Title: Re: Help with large number of wirelss mics
Post by: duane massey on January 05, 2017, 06:33:59 pm
Thanks, guys, your responses pretty much confirmed what I thought, but it's not an area I have a lot of recent experience in. I appreciate it very much.
Title: Re: Help with large number of wirelss mics
Post by: Neil White on January 06, 2017, 09:14:22 am
The 3000 does supply antenna power suitable for Shure antennas.

One thing to watch out for on the ASA3000 is that the DC bias can be turned off. The switches are hidden behind the input BNC modules which pull out from the rear of the unit and there is a small PCB mounted switch inside for each side. Definitely better to check this before building it into a rack and cabling everything.
Title: Re: Help with large number of wirelss mics
Post by: Karl Winkler on January 09, 2017, 10:02:15 am
For those of you who have deal with musicals, etc where large quantities of wireless mics are used: do you use one antennae combiner system or is there a better or cheaper method? Thanks.

I want to add on to what Pete said. Successive cascading can add the problem of ringing at the edges of the passband.

I agree that cascading more than once can cause problems, and certainly using proper active splitters for a large RF system is the way to go. The musical theater systems I've been involved with have used either Lectrosonics systems or a combination of Lectrosonics and other brands, usually Sennheiser and some Shure.

RF is RF, so if you are using combined systems, just watch for the passbands of the filters and/or splitters. Also, as Pete and others have pointed out, watch for the DC bias on the antenna lines. Most passive antennas are OK with DC, but you need to be sure (the older SNA600 dipole is not, for instance, but the newer SNA600A is). And of course if you are using active antennas (hopefully only to overcome line loss) then you'll need the DC on the line from somewhere.
Title: Re: Help with large number of wirelss mics
Post by: Ike Zimbel on January 09, 2017, 11:12:56 am
I want to add on to what Pete said. Successive cascading can add the problem of ringing at the edges of the passband.

I agree that cascading more than once can cause problems, and certainly using proper active splitters for a large RF system is the way to go. The musical theater systems I've been involved with have used either Lectrosonics systems or a combination of Lectrosonics and other brands, usually Sennheiser and some Shure.

RF is RF, so if you are using combined systems, just watch for the passbands of the filters and/or splitters. Also, as Pete and others have pointed out, watch for the DC bias on the antenna lines. Most passive antennas are OK with DC, but you need to be sure (the older SNA600 dipole is not, for instance, but the newer SNA600A is). And of course if you are using active antennas (hopefully only to overcome line loss) then you'll need the DC on the line from somewhere.
AND, since no one else has mentioned it: A proper frequency coordination is absolutely essential to making any large quantity of wireless work.
Title: Re: Help with large number of wirelss mics
Post by: Jens Palm Bacher on January 10, 2017, 02:29:23 pm
I want to add on to what Pete said. Successive cascading can add the problem of ringing at the edges of the passband.

I agree that cascading more than once can cause problems, and certainly using proper active splitters for a large RF system is the way to go.
My experience working with Sennheiser 3732/2050, Wisycom MRK960 and Shure UR4d+ is that cascading 4-6 units is not a problem in any way. Just don't connect different bands.
Title: Re: Help with large number of wirelss mics
Post by: Dan Currie on January 10, 2017, 11:29:22 pm
I want to add on to what Pete said. Successive cascading can add the problem of ringing at the edges of the passband

Can you elaborate on the 'ringing'?  Is this a reference to the edges of a units pass band being less sensitive the further it is down in the cascade?   
Title: Re: Help with large number of wirelss mics
Post by: Karl Winkler on January 26, 2017, 11:53:58 am
Can you elaborate on the 'ringing'?  Is this a reference to the edges of a units pass band being less sensitive the further it is down in the cascade?

Dan, sorry I didn't see your question earlier for some reason.

Ringing refers to fluctuations in the sensitivity of the system at the edges of the band, so on some frequencies, you can indeed see a loss of sensitivity, and on others, there is greater sensitivity, along with greater sensitivity to overloading from unwanted sources.