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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 => LAB: The Classic Live Audio Board => Topic started by: Bill Hardy on February 21, 2011, 09:11:39 PM
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Hello,
I have 8 AKG WMS 450 wireless systems, with PSU 4000 power supply and two PS 4000 antenna combiners. All in the 650 - 680 range AKG band 1.
I have recently purchased one each in the AKG band 7 and 8 to replace two units of band 1.
I need to replace my antenna to a wide band, my question is.
(1) Do I have to use AKG or can I use Shure UA870 (470-698 MHz) which is about 100$ cheaper?
(2) Do I need to upgrade the antenna combiners to a wide band?
If so do I need to replace both or can I get by with just one, seeing I only have 2 units in the lower range at present?
Thanks Bill
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u can use the Shure UA870 as the fall within your working bandwidth. If your AKG Combiners are filtered, then they will filter out unwanted frequencies anyways. Just make sure they have power inline to feed the Gain on the Shure paddles.
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Hello,
I have 8 AKG WMS 450 wireless systems, with PSU 4000 power supply and two PS 4000 antenna combiners. All in the 650 - 680 range AKG band 1.
I have recently purchased one each in the AKG band 7 and 8 to replace two units of band 1.
I need to replace my antenna to a wide band, my question is.
(1) Do I have to use AKG or can I use Shure UA870 (470-698 MHz) which is about 100$ cheaper?
Any 50 Ohm UHF-band antenna will work. RF is RF, as long as you have the right connector (BNC).
(2) Do I need to upgrade the antenna combiners to a wide band?
Yes, because the narrow band units will filter out everything outside the band they cover.
If so do I need to replace both or can I get by with just one, seeing I only have 2 units in the lower range at present?
Yes - you can change only one PS4000 for the wide-band version and you'll have what you need. Your existing PS4000 would cover four of your existing mics, then the new wide version would cover your two new mics and two existing mics.
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Just remembered something: the wide band antenna splitter needs to be first, then the narrow-band unit. I.e. antennas>wide band splitter>narrow band splitter.
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In theory, theory and practice should be the same. In practice, they are not.
Theoretically. ;)
Mac
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Thanks everyone for your input, very helpful.
One more question though, I never run my antennas more than around 30' from receivers, and combiners, would a passive or active antenna be better for application, what is the advantages and disadvantages for either one?
Thanks Bill
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Thanks everyone for your input, very helpful.
One more question though, I never run my antennas more than around 30' from receivers, and combiners, would a passive or active antenna be better for application, what is the advantages and disadvantages for either one?
Thanks Bill
The advantage of an active antenna it the higher gain. However, higher gain can also be a disadvantage it you don't actually need it, and second, points of nonlinearity (amplifiers) are where intermod products are generated. Having fewer points to generate intermod products is always good, and not amplifying signals you don't want is also good. If your antennas are close to the stage, and you use good low loss antenna cable, passive is probably better.
Mac
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Any 50 Ohm UHF-band antenna will work. RF is RF, as long as you have the right connector (BNC).
But is RF all Bill has to worry about?
Mac's comment about active antennas made me think about how some wireless receivers and antenna distribution boxes supply a DC voltage on their antenna inputs to provide power to devices further upstream. Even if the devices further upstream don't need the DC voltage, they need to tolerate it and not short it out.
I have no idea if this is an issue with the specific equipment Bill is considering, but it's always important to keep in mind when designing a wireless system.