Cable TV Powered Antenna Splitters
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Art Zemon
Jan 27, 2025, 10:44:23 AMJan 27
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Do any of you have experience with using a powered cable TV antenna splitter with wireless mic receivers? Something like this one Amazon for $60 sure looks tempting compared to a pair of Shure AXT630 units @ $1600 each. Yes, I know that the cable TV device is 75 ohms, not 50, but the loss isn't that big, roughly 0.2 dB for the 50-75 ohm conversion.
- Art Z.
--
My blog: CheerfulCurmudgeon.com
In a place where there are no humans, strive to be human. [Pirkei Avot 2:5]
Mike Glasspool
Jan 27, 2025, 11:16:15 AMJan 27
to theatre-s...@googlegroups.com
Hi Art,
I suspect the answer is no for many. I would not want to tie a show failure to the decision to save a grand on a piece of equipment.
There are also different tolerances for noise, different filters applied, etc. The ancient system isn’t just a dumb splitter - there is stuff going on in there and at the price point it isn’t worth trying it.
Breaking down the cost - let’s say you did 14 shows, your cost is just over $100 a show.
I’ve learned hard lessons in the past that you don’t cheap out on wireless. If you can’t afford to purchase, rent until you can.
Cheers,
Mike
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Jonathan Woytek
Jan 27, 2025, 11:27:06 AMJan 27
to theatre-s...@googlegroups.com
I think it is also important to note that some of the vendor-supplied antenna distribution systems also include features to operate with powered antennas, and can include power distribution to receivers. They may also include filtering to help protect from intermod and RFI.
However, I've always been curious if having one of these cheap DAs in the spares bin could help out in a pinch. For science, I ordered one of these and will throw it on an analyzer when it arrives, and I'll share the results here.
jonathan
page daniel
Jan 27, 2025, 11:27:36 AMJan 27
to theatre-s...@googlegroups.com
Probably work. If it doesn''t return to Amazon for credit.
Good RF distribution is not cheap when it comes to quality. But I use
purchased used...Shure UA844 and some 15 year old Shure UA845. The BNC
to F adapters are not very expensive but will add to cost. One of the
irritating things about splitter, including Mini-Circuits is that not
all pass DC and if you have DC piggy backed from a device they can short
out that power which is usually a surface mount resistor. DC blocks
with BC connectors are not cheap. Shure 2 way splitters do not have
this problem. If you need to power RF amplifiers or powered antennas
for long cable runs Bias Tee's are not cheap.
For those who are old school RF amplifiers are to be avoided because
they insert some noise and at best placed near antennas only to make up
for cable runs, but every splitter or daisy chained receiver has one.
Shure engineering told me that it one can daisy chain ULXD4 Quads up to
two for 12 receivers despite what is in their literature. Yeah, so noise
is added at every step of the way. But watch out! Fine print is that one
should only daisy chain the same bands as the RF amps are narrow band.
So 24 receivers need at least a two way splitter, or with multiple bands
an antenna distro. My Lectrosonics venues have worked for me with 4
daisy chained for a total of 30 receivers. But they add about 1 dB for
some unknown reason at each stage as does the old Shure distros so it is
good to judicious 3 dB pad for the last two. Or just use 75 ohm BNC
patch cords and get a dB or so loss from the possible miss match.
Looking for corrections from others who have had experience.
page daniel
.
On 2025-01-27 09:44, Art Zemon wrote:
> Do any of you have experience with using a powered cable TV antenna
> splitter with wireless mic receivers? Something like this one Amazon
> for $60 [1] sure looks tempting compared to a pair of Shure AXT630
>
> ___In a place where there are no humans, strive to be human. [Pirkei
> Avot 2:5]_
>
>
> Links:
> ------
> [1]
> https://www.amazon.com/Reliable-Cable-Distribution-Amplifier-Terminators/dp/B0CBNT8FYG
> [2] https://CheerfulCurmudgeon.com/
> [3]
> https://groups.google.com/d/msgid/theatre-sound-list/CAN%2BRJV5LQrXcono0O87A7uk-DkYXBFJaaYsW8_duGs8-kscKUw%40mail.gmail.com?utm_medium=email&utm_source=footer
Good RF distribution is not cheap when it comes to quality. But I use
purchased used...Shure UA844 and some 15 year old Shure UA845. The BNC
to F adapters are not very expensive but will add to cost. One of the
irritating things about splitter, including Mini-Circuits is that not
all pass DC and if you have DC piggy backed from a device they can short
out that power which is usually a surface mount resistor. DC blocks
with BC connectors are not cheap. Shure 2 way splitters do not have
this problem. If you need to power RF amplifiers or powered antennas
for long cable runs Bias Tee's are not cheap.
For those who are old school RF amplifiers are to be avoided because
they insert some noise and at best placed near antennas only to make up
for cable runs, but every splitter or daisy chained receiver has one.
Shure engineering told me that it one can daisy chain ULXD4 Quads up to
two for 12 receivers despite what is in their literature. Yeah, so noise
is added at every step of the way. But watch out! Fine print is that one
should only daisy chain the same bands as the RF amps are narrow band.
So 24 receivers need at least a two way splitter, or with multiple bands
an antenna distro. My Lectrosonics venues have worked for me with 4
daisy chained for a total of 30 receivers. But they add about 1 dB for
some unknown reason at each stage as does the old Shure distros so it is
good to judicious 3 dB pad for the last two. Or just use 75 ohm BNC
patch cords and get a dB or so loss from the possible miss match.
Looking for corrections from others who have had experience.
page daniel
.
On 2025-01-27 09:44, Art Zemon wrote:
> Do any of you have experience with using a powered cable TV antenna
> splitter with wireless mic receivers? Something like this one Amazon
> units @ $1600 each. Yes, I know that the cable TV device is 75 ohms,
> not 50, but the loss isn't that big, roughly 0.2 dB for the 50-75 ohm
> conversion.
>
> - Art Z.
>
> --
>
> My blog: CheerfulCurmudgeon.com [2]
> not 50, but the loss isn't that big, roughly 0.2 dB for the 50-75 ohm
> conversion.
>
> - Art Z.
>
> --
>
>
> ___In a place where there are no humans, strive to be human. [Pirkei
> Avot 2:5]_
>
> --
> Please edit unnecessary quoted text out of your reply.
> Take non-theatre-sound topics to private email.
>
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> [3].
> --
> Please edit unnecessary quoted text out of your reply.
> Take non-theatre-sound topics to private email.
>
> ---
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>
>
> Links:
> ------
> [1]
> https://www.amazon.com/Reliable-Cable-Distribution-Amplifier-Terminators/dp/B0CBNT8FYG
> [2] https://CheerfulCurmudgeon.com/
> [3]
> https://groups.google.com/d/msgid/theatre-sound-list/CAN%2BRJV5LQrXcono0O87A7uk-DkYXBFJaaYsW8_duGs8-kscKUw%40mail.gmail.com?utm_medium=email&utm_source=footer
Nick Kourtides
Jan 27, 2025, 11:48:32 AMJan 27
to theatre-s...@googlegroups.com
Many years ago, we’d get RF distributors from the NYC shops that were basically a cascade of Archer TV band passive splitters and an RF amp with clicked attenuators at the head. So a mix of Radio Shack and MiniCircuits parts.
I actually built an active distro out once of MiniCircuits parts, some inline filters, and very linear amplifiers. I had a specific application for an installation and wanted to control the total gain through the unit while providing no user controls. It was definitely cheaper than the retail Shure and Sennheiser distributors available at the time. Professional 8 output distros were well made, metal-chassis affairs, and properly expensive.
To view this discussion visit https://groups.google.com/d/msgid/theatre-sound-list/981f427f8c43cd46e9c05f3d31a0b1ed%40pagedaniel.com.
Aaron Yoffe
Jan 27, 2025, 11:59:36 AMJan 27
to theatre-s...@googlegroups.com
Art-
Theoretically, there’s a laundry list of reasons why that might cause problems, primarily insertion loss adapting from F connectors to BNC and impedance mismatches.
That being said, once upon a time I bought some powered splitters and a slew of adapters, but never actually got around to trying it - I don’t have a “home” theater I work in; I bring gear in and out for every show, and the homebrew CATV splitter solution was going to be messy, ungainly, and involve too many parts to lose…
Since then, Phenyx wireless came out with a very reasonable compromise in terms of cost - normally I wouldn’t consider their equipment (we have a pair of their handhelds at my day job which I loathe), but this has worked out well. Who knows how long it will last…
We use those paddles and their distro to feed Sennheiser ASAs I’ve collected over time for a reasonable price by watching eBay.
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Steven Devino
Jan 27, 2025, 1:32:44 PMJan 27
to theatre-s...@googlegroups.com
There are also other distribution options besides Shure. Some of which will cost significantly less than that particular model
Steven Devino
Director Product Management
RF Venue
On Jan 27, 2025, at 10:44 AM, Art Zemon <a...@zemon.name> wrote:AXT630
Daniel Chin
Jan 27, 2025, 4:52:43 PMJan 27
to theatre-s...@googlegroups.com
What Page said. Seriously.
I've not used that exact unit, but a friend of mine (a retired
commercial RF engineer now working in live entertainment) has done
similar with older, discontinued Shure analog units on custom LPDA
antennas in relatively short range applications. I've not tried splits
that large, but as others on this list have also done, I've used passive
75 ohm splits for wireless microphones and it's fine. As you've pointed
out, the impedance mismatch loss is pretty small. It's not ideal, but it
works well enough in a lot of settings. I think I have a similar model
that came with my house that I might get around to bench testing one of
these days to see how it behaves relative to some more professional
models. Unfortunately for this thread, that probably won't happen
anytime soon.
It's all RF. Whether it's DTV or wireless microphones, the required SNR
is similar enough and the pass bands are basically the same since we're
secondary users on their spectrum.
You didn't say what model wireless you're using. For me, if I were using
Axient, I'd probably get a Shure UA844+SWB and call it good and have it
all match and be rackable and easy for a lot less than the price of
another channel of wireless. If I already had the needed cabling, I'd
get the LC version and save the $80 (total price of $534 with free
shipping from pretty much any dealer if buying new). With Axient's
cascade ports, you could get a pretty decent channel count with a single
distro. If you're touring and or need to be frequently managing gain
structure or filtering or monitoring your distribution, the AXT630 would
make sense. But if it's a static install in a simple and easy
environment, you're probably fine. The selectable input filtering of the
AXT630 could also be a big help—or unnecessary—depending on your
environment. If you go with one of your cheaper options, you could even
use some money saved by buying passband filters and putting them before
the powered splits.
The biggest concern I'd have for whether it'll actually work for you is
what you need for DC handling as Page pointed out. Actual functionality
will depend on your receivers and your antennas. You could very easily
get to a point where you spend more in cabling and DC blocks and/or
Bias-Ts than you save.
Ultimately, you largely get what you pay for. It'll probably work from
the standpoint of passing signal, but there are good reasons for the
higher costs of professional, rack-mountable units. Just as a $200 power
amplifier will drive speakers and a $2,000 amp will also drive speakers,
they're not necessarily completely interchangeable and which one is more
appropriate for the application depends on both budget and design
objectives and that's only after establishing circuit compatibility.
What do you actually need and what is your environment like?
Daniel Chin
------ Original Message ------
From "page daniel" <pa...@pagedaniel.com>
To theatre-s...@googlegroups.com
Date 1/27/2025 10:27:30 AM
Subject Re: [theatre-sound-list] Cable TV Powered Antenna Splitters
>To view this discussion visit https://groups.google.com/d/msgid/theatre-sound-list/981f427f8c43cd46e9c05f3d31a0b1ed%40pagedaniel.com.
I've not used that exact unit, but a friend of mine (a retired
commercial RF engineer now working in live entertainment) has done
similar with older, discontinued Shure analog units on custom LPDA
antennas in relatively short range applications. I've not tried splits
that large, but as others on this list have also done, I've used passive
75 ohm splits for wireless microphones and it's fine. As you've pointed
out, the impedance mismatch loss is pretty small. It's not ideal, but it
works well enough in a lot of settings. I think I have a similar model
that came with my house that I might get around to bench testing one of
these days to see how it behaves relative to some more professional
models. Unfortunately for this thread, that probably won't happen
anytime soon.
It's all RF. Whether it's DTV or wireless microphones, the required SNR
is similar enough and the pass bands are basically the same since we're
secondary users on their spectrum.
You didn't say what model wireless you're using. For me, if I were using
Axient, I'd probably get a Shure UA844+SWB and call it good and have it
all match and be rackable and easy for a lot less than the price of
another channel of wireless. If I already had the needed cabling, I'd
get the LC version and save the $80 (total price of $534 with free
shipping from pretty much any dealer if buying new). With Axient's
cascade ports, you could get a pretty decent channel count with a single
distro. If you're touring and or need to be frequently managing gain
structure or filtering or monitoring your distribution, the AXT630 would
make sense. But if it's a static install in a simple and easy
environment, you're probably fine. The selectable input filtering of the
AXT630 could also be a big help—or unnecessary—depending on your
environment. If you go with one of your cheaper options, you could even
use some money saved by buying passband filters and putting them before
the powered splits.
The biggest concern I'd have for whether it'll actually work for you is
what you need for DC handling as Page pointed out. Actual functionality
will depend on your receivers and your antennas. You could very easily
get to a point where you spend more in cabling and DC blocks and/or
Bias-Ts than you save.
Ultimately, you largely get what you pay for. It'll probably work from
the standpoint of passing signal, but there are good reasons for the
higher costs of professional, rack-mountable units. Just as a $200 power
amplifier will drive speakers and a $2,000 amp will also drive speakers,
they're not necessarily completely interchangeable and which one is more
appropriate for the application depends on both budget and design
objectives and that's only after establishing circuit compatibility.
What do you actually need and what is your environment like?
Daniel Chin
------ Original Message ------
From "page daniel" <pa...@pagedaniel.com>
To theatre-s...@googlegroups.com
Date 1/27/2025 10:27:30 AM
Subject Re: [theatre-sound-list] Cable TV Powered Antenna Splitters
Art Zemon
Jan 27, 2025, 5:30:35 PMJan 27
to theatre-s...@googlegroups.com
On Mon, Jan 27, 2025 at 3:52 PM 'Daniel Chin' via theatre-sound <theatre-s...@googlegroups.com> wrote:
What Page said. Seriously.
<snip>
What do you actually need and what is your environment like?
I'm definitely with you on the "do it right or don't bother" bandwagon. But I'm trying to do something that has no budget and no hope of getting any money other than from my own wallet. This is the environment in our sanctuary
Everything works fine but it's messy and offends my desire for a clean installation. It is only about 100 feet to the transmitters and there is a wall 12 feet to the right of the receivers.
I am toying with the idea of moving the antennas over to the wall. If I use passive 2-way splitters, I only need to put 8 antennas over there. That will cost me under $300 for coax and connectors.
And then I thought of DTV powered splitters and wondered... hmmmm... only run 2 coax cables up the wall instead of 8, and at $60 a piece for the splitters, that's pretty close to the same amount of money as just remoting 8 antennas.
BTW, I'll build my own cables so I won't have to mess with connector converters. I will just crimp BNC onto everything.
-- Art Z.
My blog: CheerfulCurmudgeon.com
Nick Kourtides
Jan 27, 2025, 5:56:12 PMJan 27
to theatre-s...@googlegroups.com
At the moment, you have loose antennas potentially detuning each other, but cheap active electronics in a consumer television splitter (or anything tbh) can introduce intermodulation products that are actually worse.
Best practices here would be to use passive LPDA or similar antennas to achieve forward efficiency of pickup. Use the shortest possible low-loss 50ohm coaxial cable and well crimped, high quality connectors. If you must add gain, with active components, they should be high quality, with published specs for intermodulation distortion products based on RF signal input, and only add enough gain to overcome necessary losses: like if you must run cable lengths in the 10s of meters to achieve line-of-sight, or the necessary splitting losses from distribution to multiple receivers.
You’ve got a pile of single channel receivers, so realistically this requires a relatively expensive large format distributor, or cascading multiple smaller ones. All of this has costs, and signal loss/intermodulation potential.
You also will struggle if you just try to mount the omnidirectional whip antennas remotely from the receivers - typically these designs rely on the chassis they are mounted to to provide the needed ground plane to make the antenna work efficiently. You can improvise this, but it will require materials, cost, and take up space in potentially very visible ways.
There’s not really an easy answer to this question without costs, complexity, etc.
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page daniel
Jan 27, 2025, 6:13:25 PMJan 27
to theatre-s...@googlegroups.com
A better idea. Two passive 4 way cable tV splitters is 20 dollar and
cost you less than 7 dB and then add the coax loss for a bit more...so
say 10 dB and 2 Antennas for 8 channels. Leave half antennas at the
receivers and get better diversity. And save money while making an
improvement. Actually 10 dB is not a lot in the RF world for short
cables and line of sight. For wireless I like a good distance. For
theater sometimes I like to put one antenna where I can see the RF from
the green room, for crazy shows with people rolling around on the floor
antennas below the stage have been useful. Oh dirty little fact not
mentioned is that one can count on a human body with the pack on the
back to absorb 10 dB. two in a row..ugh 20 dB. For wireless FM mics it
does not take a lot to get a clean signal if noise and interference is
not greater than the signal from transmitter at the receiver. How much
over kill do we need to spend money on when the audio is the same good
quality.
Yeah I see stuff all the time that I wonder how it works. Often it is
neatly installed, but violates best practices. For bad venues, or lots
of RF interference, knowing what best practices are and making use of
them is important..but most of the time all the expense I put into
powered LPDA's and making up cable loss is just because they are already
sitting on the shelf and I may never visit the venue.
page
On 2025-01-27 16:30, Art Zemon wrote:
> On Mon, Jan 27, 2025 at 3:52 PM 'Daniel Chin' via theatre-sound
> <theatre-s...@googlegroups.com> wrote:
>
>> What Page said. Seriously.
>
> <snip>
>
>> What do you actually need and what is your environment like?
>
> I'm definitely with you on the "do it right or don't bother"
> bandwagon. But I'm trying to do something that has no budget and no
> hope of getting any money other than from my own wallet. This is the
> environment in our sanctuary
>
> [2].
>
>
> Links:
> ------
> [1] https://CheerfulCurmudgeon.com/
> [2]
> https://groups.google.com/d/msgid/theatre-sound-list/CAN%2BRJV5%2BC4VU9hMSKk3YFcktS1sqGRAB8ALn6FSV%2Bc6KCzdqEQ%40mail.gmail.com?utm_medium=email&utm_source=footer
cost you less than 7 dB and then add the coax loss for a bit more...so
say 10 dB and 2 Antennas for 8 channels. Leave half antennas at the
receivers and get better diversity. And save money while making an
improvement. Actually 10 dB is not a lot in the RF world for short
cables and line of sight. For wireless I like a good distance. For
theater sometimes I like to put one antenna where I can see the RF from
the green room, for crazy shows with people rolling around on the floor
antennas below the stage have been useful. Oh dirty little fact not
mentioned is that one can count on a human body with the pack on the
back to absorb 10 dB. two in a row..ugh 20 dB. For wireless FM mics it
does not take a lot to get a clean signal if noise and interference is
not greater than the signal from transmitter at the receiver. How much
over kill do we need to spend money on when the audio is the same good
quality.
Yeah I see stuff all the time that I wonder how it works. Often it is
neatly installed, but violates best practices. For bad venues, or lots
of RF interference, knowing what best practices are and making use of
them is important..but most of the time all the expense I put into
powered LPDA's and making up cable loss is just because they are already
sitting on the shelf and I may never visit the venue.
page
On 2025-01-27 16:30, Art Zemon wrote:
> On Mon, Jan 27, 2025 at 3:52 PM 'Daniel Chin' via theatre-sound
> <theatre-s...@googlegroups.com> wrote:
>
>> What Page said. Seriously.
>
> <snip>
>
>> What do you actually need and what is your environment like?
>
> I'm definitely with you on the "do it right or don't bother"
> bandwagon. But I'm trying to do something that has no budget and no
> hope of getting any money other than from my own wallet. This is the
> environment in our sanctuary
>
> Everything works fine but it's messy and offends my desire for a clean
> installation. It is only about 100 feet to the transmitters and there
> is a wall 12 feet to the right of the receivers.
>
> I am toying with the idea of moving the antennas over to the wall. If
> I use passive 2-way splitters, I only need to put 8 antennas over
> there. That will cost me under $300 for coax and connectors.
>
> And then I thought of DTV powered splitters and wondered... hmmmm...
> only run 2 coax cables up the wall instead of 8, and at $60 a piece
> for the splitters, that's pretty close to the same amount of money as
> just remoting 8 antennas.
>
> BTW, I'll build my own cables so I won't have to mess with connector
> converters. I will just crimp BNC onto everything.
>
> -- Art Z.
>
> --
>
> My blog: CheerfulCurmudgeon.com [1]
> installation. It is only about 100 feet to the transmitters and there
> is a wall 12 feet to the right of the receivers.
>
> I am toying with the idea of moving the antennas over to the wall. If
> I use passive 2-way splitters, I only need to put 8 antennas over
> there. That will cost me under $300 for coax and connectors.
>
> And then I thought of DTV powered splitters and wondered... hmmmm...
> only run 2 coax cables up the wall instead of 8, and at $60 a piece
> for the splitters, that's pretty close to the same amount of money as
> just remoting 8 antennas.
>
> BTW, I'll build my own cables so I won't have to mess with connector
> converters. I will just crimp BNC onto everything.
>
> -- Art Z.
>
> --
>
>
> ___In a place where there are no humans, strive to be human. [Pirkei
> Avot 2:5]_
>
> --
> Please edit unnecessary quoted text out of your reply.
> Take non-theatre-sound topics to private email.
>
> ---
> You received this message because you are subscribed to the Google
> Groups "theatre-sound" group.
> To unsubscribe from this group and stop receiving emails from it, send
> an email to theatre-sound-l...@googlegroups.com.
> To view this discussion visit
> https://groups.google.com/d/msgid/theatre-sound-list/CAN%2BRJV5%2BC4VU9hMSKk3YFcktS1sqGRAB8ALn6FSV%2Bc6KCzdqEQ%40mail.gmail.com
> ___In a place where there are no humans, strive to be human. [Pirkei
> Avot 2:5]_
>
> --
> Please edit unnecessary quoted text out of your reply.
> Take non-theatre-sound topics to private email.
>
> ---
> You received this message because you are subscribed to the Google
> Groups "theatre-sound" group.
> To unsubscribe from this group and stop receiving emails from it, send
> an email to theatre-sound-l...@googlegroups.com.
> To view this discussion visit
> [2].
>
>
> Links:
> ------
> [1] https://CheerfulCurmudgeon.com/
> [2]
> https://groups.google.com/d/msgid/theatre-sound-list/CAN%2BRJV5%2BC4VU9hMSKk3YFcktS1sqGRAB8ALn6FSV%2Bc6KCzdqEQ%40mail.gmail.com?utm_medium=email&utm_source=footer
Simon Eves
Jan 27, 2025, 6:26:08 PMJan 27
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(posted this an hour ago from the wrong send address and it bounced, and there have been a couple more replies since, but...)
The biggest advantage will come from better antennas and better diversity behavior. As my friend Aaron said, the $340 Phenyx-Pro kit (two active paddles, active 4-way splitter) is a good deal. Obviously you have nine receivers to cover, so you'll still need maybe passive splitters to expand the four outputs of the PP box (presumably giving you twelve or sixteen outputs for future expansion... not sure if unused ones need specific termination for impedance matching), but then at least you have a stronger signal upstream of those so any electronic compromise is hopefully reduced. I would recommend mounting the paddle antennas apart and high up (or at least 100% clear line-of-sight to the whole stage) for better diversity coverage (they have standard 5/8" mic stand mounts). Since getting that kit about two years ago (used to feed three racks each with eight Sennheiser G3s and two ASAs, and then a Shure ULX handheld receiver) we haven't had a single RF issue (no splats, less hiss) in any of our usual venues.
The biggest advantage will come from better antennas and better diversity behavior. As my friend Aaron said, the $340 Phenyx-Pro kit (two active paddles, active 4-way splitter) is a good deal. Obviously you have nine receivers to cover, so you'll still need maybe passive splitters to expand the four outputs of the PP box (presumably giving you twelve or sixteen outputs for future expansion... not sure if unused ones need specific termination for impedance matching), but then at least you have a stronger signal upstream of those so any electronic compromise is hopefully reduced. I would recommend mounting the paddle antennas apart and high up (or at least 100% clear line-of-sight to the whole stage) for better diversity coverage (they have standard 5/8" mic stand mounts). Since getting that kit about two years ago (used to feed three racks each with eight Sennheiser G3s and two ASAs, and then a Shure ULX handheld receiver) we haven't had a single RF issue (no splats, less hiss) in any of our usual venues.
To view this discussion visit https://groups.google.com/d/msgid/theatre-sound-list/e8affadbaebcf55c72dbeeae5a43cb42%40pagedaniel.com.
H. Cohen
Jan 27, 2025, 8:12:19 PMJan 27
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The impedance mismatch is moot:
- Antennas are transducers with their impedance varying with frequency. They are 50Ω at only one, maybe two frequencies. Across the entire bandwidth of a typical wideband (>200MHz) antenna used for wireless microphone systems the impedance can vary from 37.5Ω to 110Ω.
- Wireless microphone receiver front ends are not 50Ω. They too vary due to the wide bandwidth input and source frequency; they'll be anywhere between 50Ω-75Ω (ask any of the actual design engineers).
In short, your wireless microphone system already has a perpetual impedance mismatch, and has forever.
If one goes back to the early days (as Nick K recalled), wireless mic distribution systems - even those built by the revered Germans - were off the shelf CATV amplified and passive splitters.
The more important attributes are for any active RF device:
- Noise figure
- P1
- IP3
- Gain
- Linearity
- Can it provide bias voltage to antennas that require it
- [My pet peeve] Do you want to trust a show and your reputation on a cheap unknown from Amazon? At least buy known brand name CATV products that publish [most] real specifications:
* Blonder Tongue (the best IMO)
* Cabletronix
* Calrad
* Thor
- Antennas are transducers with their impedance varying with frequency. They are 50Ω at only one, maybe two frequencies. Across the entire bandwidth of a typical wideband (>200MHz) antenna used for wireless microphone systems the impedance can vary from 37.5Ω to 110Ω.
- Wireless microphone receiver front ends are not 50Ω. They too vary due to the wide bandwidth input and source frequency; they'll be anywhere between 50Ω-75Ω (ask any of the actual design engineers).
In short, your wireless microphone system already has a perpetual impedance mismatch, and has forever.
If one goes back to the early days (as Nick K recalled), wireless mic distribution systems - even those built by the revered Germans - were off the shelf CATV amplified and passive splitters.
The more important attributes are for any active RF device:
- Noise figure
- P1
- IP3
- Gain
- Linearity
- Can it provide bias voltage to antennas that require it
- [My pet peeve] Do you want to trust a show and your reputation on a cheap unknown from Amazon? At least buy known brand name CATV products that publish [most] real specifications:
* Blonder Tongue (the best IMO)
* Cabletronix
* Calrad
* Thor
Henry Cohen
Russwig
Jan 28, 2025, 1:10:50 AMJan 28
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Art;
I have built 3 systems using PCT (https://www.pctinternational.com/product/pct-vc-9uip/). Each was for 24 Shure SLX systems. Each worked flawlessly. As far as I know they are all still in use. One of the three coupled a Shure UA844 system to incorporate with Shure Antenna Paddles that the client already owned. The other two used Kent Electronics Log Periodics (https://www.wa5vjb.com/products1.html). This was all based on a video I caught by Drew Basher (https://www.youtube.com/watch?v=SH3VKHcwDj0&t=1441s).
YMMV! RW...
On Mon, Jan 27, 2025 at 7:44 AM Art Zemon <a...@zemon.name> wrote:
--
Please edit unnecessary quoted text out of your reply.
Take non-theatre-sound topics to private email.
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Russwig
Jan 28, 2025, 1:19:31 AMJan 28
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I forgot to add, use Shure Wireless Workbench to find the best tuning for your Mics.
RW...
Art Zemon
Jan 28, 2025, 12:18:35 PMJan 28
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I saw that video, too. Pretty interesting. It makes perfect sense since (as someone mentioned above) this is just RF in the 400-600 MHz band. There isn't anything magic about Shure wireless receivers.
-- Art Z.
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Russwig
Jan 28, 2025, 1:01:28 PMJan 28
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Art;
Do try it. I was amazed by how much better it worked for me. My primary use was for a theater that did 3 musicals a year in about a hundred and fifty seat house. But I also used it on a similar rig that was in a 375 seat venue, with similar results. Don't forget Shure Wireless Workbench, regardless of whose brands of mics you have,
RW...
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Daniel Chin
Jan 28, 2025, 6:44:23 PMJan 28
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The Kent LPDAs are an excellent value if you're willing to do some work yourself. One word of caution about them: they're DC grounded to help with some resonances and minimize ESD issues. It will short your bias-T if you happen to have one connected (even if it's internal to a receiver or distro). What I've done in the past is cut the trace right behind the SMA connector and bridge it with a surface mount capacitor. That way I can keep from worrying about bias voltage being present in case I want it for a different set of antennas with an amp built in (such as the Shure UA874) or if I want to use a separate RF amp and I don't have to remember an in-line DC block when hooking them up.
Daniel Chin
Subject Re: [theatre-sound-list] Cable TV Powered Antenna Splitters
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