ProSoundWeb Community
Sound Reinforcement - Forums for Live Sound Professionals - Your Displayed Name Must Be Your Real Full Name To Post In The Live Sound Forums => LAB Lounge => Topic started by: David Allred on October 24, 2013, 07:16:05 PM
-
Looking at a Shure BLX24 or 24R system for an install. It specs as 300' line of sight. I want to rack it in the audio closet. I only need to transmit 100' (absolute max), but there will be a block wall between (7' from the receiver if it makes a difference). Any hope?
Thanks
-
Looking at a Shure BLX24 or 24R system for an install. It specs as 300' line of sight. I want to rack it in the audio closet. I only need to transmit 100' (absolute max), but there will be a block wall between (7' from the receiver if it makes a difference). Any hope?
Thanks
No guarantees.
Mount the antennas on the outside of the wall for line of sight. Can you drill a hole through the wall to run cables through?
-
yes I can drill a hole. How do I extent the antenna?
-
yes I can drill a hole. How do I extent the antenna?
To replace $20 worth of wire will require at least $1000 of RF if you want reliability.
Drill the damn hole and be done with this silliness.
-
To replace $20 worth of wire will require at least $1000 of RF if you want reliability.
Drill the damn hole and be done with this silliness.
Tim, I'm feeling obtuse. Are you saying I can extend the antenna through the wall for $20? Who offers such a wire?
Thanks
-
Tim, I'm feeling obtuse. Are you saying I can extend the antenna through the wall for $20? Who offers such a wire?
Thanks
You can get ready made cables from a local supplier. Look in the owners manual. It's usually 75ohm cable with BNC connectors. Not too long....shorter the better.
-
Tim, I'm feeling obtuse. Are you saying I can extend the antenna through the wall for $20? Who offers such a wire?
I believe he was saying to drill the hole and run a wire as opposed to any RF solution.
-
I believe he was saying to drill the hole and run a wire as opposed to any RF solution.
Am I to understand that by wire you mean a wired mic? The client wants a wireless mic to avoid dragging a cable thru patrons over a 75' use area.
-
Am I to understand that by wire you mean a wired mic? The client wants a wireless mic to avoid dragging a cable thru patrons over a 75' use area.
David, your use of the word 'client' implies that someone is paying you to do this. However, the questions you are asking imply that you aren't qualified to do this...
-
Am I to understand that by wire you mean a wired mic? The client wants a wireless mic to avoid dragging a cable thru patrons over a 75' use area.
No, we are talking about mounting the antennas in a different location so they will be line of sight with the transmitter (mic) and running antenna wire to the antennas, leaving the receiver in the closet.
-
Am I to understand that by wire you mean a wired mic? The client wants a wireless mic to avoid dragging a cable thru patrons over a 75' use area.
You should mount the antenna(s) on the client side of the wall and get a run of the appropriate coax.
-
It's usually 75ohm cable with BNC connectors.
It shouldn't be 75ohm, that's video cable. For audio over RF the industry standard is 50ohm cable and connectors.
-
David, your use of the word 'client' implies that someone is paying you to do this. However, the questions you are asking imply that you aren't qualified to do this...
No. I just have no experience attempting to transmit through block walls. The manual offers no extension mention, nor the antenna type (75 ohm or otherwise). Shure lists no antenna accessories for this model. For this reason I come seeking knowledge.
-
Looking at a Shure BLX24 or 24R system for an install. It specs as 300' line of sight. I want to rack it in the audio closet. I only need to transmit 100' (absolute max), but there will be a block wall between (7' from the receiver if it makes a difference). Any hope?
Thanks
There is no specification on the antennas in the user guide, but assuming the connectors are BNC you should be able to remote mount the antennas and use low loss cable to connect the antennas in the room to the receivers in the rack. You should use something like Belden 9913 or RG8U. There should be no tight bends in the cable. The antennas should be mounted at least 5' apart.
Mac
-
No. I just have no experience attempting to transmit through block walls. The manual offers no extension mention, nor the antenna type (75 ohm or otherwise). Shure lists no antenna accessories for this model. For this reason I come seeking knowledge.
What's the model of the wireless unit? If it is something like the PGX that does not have detachable antennas, there is nothing you can do other than put the receiver in line of sight of the transmitter. If it a model like the ULX then a simple BNC cable extension to relocate the antennas to a line of sight position for the transmitter is what you're looking for.
-
It shouldn't be 75ohm, that's video cable. For audio over RF the industry standard is 50ohm cable and connectors.
50ohm. I had 75 on the brain.
David, I would suggest contacting a qualified person in your area to take care of this for you.
-
What's the model of the wireless unit? If it is something like the PGX that does not have detachable antennas, there is nothing you can do other than put the receiver in line of sight of the transmitter. If it a model like the ULX then a simple BNC cable extension to relocate the antennas to a line of sight position for the transmitter is what you're looking for.
Shure BLX24 series. The rack mountable version (R) has detachable antennas. I have seen 75ohm & 50ohm cable, BNC and PL259 (I think) connectors. Is there anyway to know for sure which?
-
50ohm. I had 75 on the brain.
David, I would suggest contacting a qualified person in your area to take care of this for you.
Can your define "qualified person"? Ham radio supply store?
-
Can your define "qualified person"? Ham radio supply store?
Webster Dictionary
qual·i·fied
adjective \ˈkwä-lə-ˌfīd\
: having the necessary skill, experience, or knowledge to do a particular job or activity : having the qualifications to do something
-
http://cdn.shure.com/publication/upload/438/us_pro_intro_to_wireless_ea.pdf
http://cdn.shure.com/ckeditor_assets/attachments/231/2013-02-15_b_Advanced_Wireless_Seminar_2013.pdf
http://www.shure.com/americas/support/training/materials#video-2324803936001
http://cdn.shure.com/ckeditor_assets/attachments/320/2012-09-25_Advanced_Wireless_Seminar_DM.pdf
http://forums.prosoundweb.com/index.php/topic,146661.0.html
-
Webster Dictionary
qual·i·fied
adjective \ˈkwä-lə-ˌfīd\
: having the necessary skill, experience, or knowledge to do a particular job or activity : having the qualifications to do something
Funny. ;)
I am sure no one here has ever done anything for the first time. ::) Made their first custom mic cable. Replaced a popped capacitor on a x-over board. Connected their first powered sub. Replaced a horn diaphragm. Mixed monitors from FOH. Used crunchy peanut butter, instead of smooth on a PB&J.
-
http://cdn.shure.com/publication/upload/438/us_pro_intro_to_wireless_ea.pdf
http://cdn.shure.com/ckeditor_assets/attachments/231/2013-02-15_b_Advanced_Wireless_Seminar_2013.pdf
http://www.shure.com/americas/support/training/materials#video-2324803936001
http://cdn.shure.com/ckeditor_assets/attachments/320/2012-09-25_Advanced_Wireless_Seminar_DM.pdf
http://forums.prosoundweb.com/index.php/topic,146661.0.html
Thanks
-
Funny. ;)
I am sure no one here has ever done anything for the first time. ::) Made their first custom mic cable. Replaced a popped capacitor on a x-over board. Connected their first powered sub. Replaced a horn diaphragm. Mixed monitors from FOH. Used crunchy peanut butter, instead of smooth on a PB&J.
Two ways to learn how:
1. Trial and error
2. Learn from an expert
It appears you're not grasping what to do through this forum format. Therefore, I would suggest finding somebody who is familiar with this to show you in person...then you'll know forever.
-
Two ways to learn how:
1. Trial and error
2. Learn from an expert
It appears you're not grasping what to do through this forum format. Therefore, I would suggest finding somebody who is familiar with this to show you in person...then you'll know forever.
Paying for the benefit of another person's experience is tuition. Lots to be said for that: happy clients, smarter me/employees, creating relationships with people who help me look good.
"If I have seen further... it is because I have stood on the shoulders of giants..."
-
Paying for the benefit of another person's experience is tuition. Lots to be said for that: happy clients, smarter me/employees, creating relationships with people who help me look good.
"If I have seen further... it is because I have stood on the shoulders of giants..."
"if I give you one fish you will have one good meal. If I show you how to fish you eat good every meal."
-
"if I give you one fish you will have one good meal. If I show you how to fish you eat good every meal."
"The mighty lager with the great taste... of fish!" - M. Python
-
Instead of paying an expert. I posted here and got some usable info. Contacting Shure, I got some useful info. Watching a webinar posted to a reply on this thread. I found what I was after. Am I RF expert? Far from it. But I now feel comfortable enough to proceed. It is now in the hands of my client to determine if they want to pay the extra $220 for the 2) 25 ft antenna wires and the 1/2 wavelength antennas to replace the 1/4 wavelengths that are stock on the BLX system, so the receiver can be in the sound room. If not, on a perch it goes. If we're lucky, might can leave the receiver in the sound room with no holes to be drilled anyway.
The purpose of this great forum is to do what just happened. Those who know, sharing with those who don't. And that is teaching someone how to fish. Job well done.
-
"if I give you one fish you will have one good meal. If I show you how to fish you eat good every meal."
Teach a man to fish, and you can sell him a ton of accessories.
-
Teach a man to fish, and you can sell him a ton of accessories.
And eventually he will buy a boat. The widows and orphans will wail, and gnash their teeth.
-
If the pond is in the woods and a tree falls and crushes his skull, will you hear the fish.
-
Teach a man to fish, and you can sell him a ton of accessories.
"Give a man a fish and he will eat for a day. Teach a man to fish and he will buy an ugly hat".
- Scott Adams, Dilbert creator.
Steve.
-
If the pond is in the woods and a tree falls and crushes his skull, will you hear the fish.
That is deep.
-
It shouldn't be 75ohm, that's video cable. For audio over RF the industry standard is 50ohm cable and connectors.
For what it's worth, I've used 100' and greater lengths of standard RG6 75 ohm video cable (Belden 1694A) with Shure ULX receivers and UA870 antennas many times with no appreciable loss of RF performance. Also with Lectrosonics IFB transmitters and Shure PA805 antennas. I assume it would work fine with IEM transmitter as well, but I've never tried.
I know it's not "right", but hey, it works.
-
For what it's worth, I've used 100' and greater lengths of standard RG6 75 ohm video cable (Belden 1694A) with Shure ULX receivers and UA870 antennas many times with no appreciable loss of RF performance. Also with Lectrosonics IFB transmitters and Shure PA805 antennas. I assume it would work fine with IEM transmitter as well, but I've never tried.
I know it's not "right", but hey, it works.
It won't work as well with IEM transmitters. The receive antenna has an impedance that varies with frequency just like a speaker, so the 50Ω impedance spec is not dead on anyway. Very often RG59 will work fine as antenna cable for wireless mics, it often has less loss than RG58 which is 50Ω. It has more loss however than good antenna cable.
For IEM transmitters the antenna/cable combination is much more important to keep at 50Ω.
Mac
-
It won't work as well with IEM transmitters. The receive antenna has an impedance that varies with frequency just like a speaker, so the 50Ω impedance spec is not dead on anyway. Very often RG59 will work fine as antenna cable for wireless mics, it often has less loss than RG58 which is 50Ω. It has more loss however than good antenna cable.
For IEM transmitters the antenna/cable combination is much more important to keep at 50Ω.
Mac
I agree. But like I said, I've used that same 75 ohm RG6 on IFB transmitters with good results. Those are probably higher powered than a typical IEM transmitter though, which I'm sure makes a difference.
-
It won't work as well with IEM transmitters. The receive antenna has an impedance that varies with frequency just like a speaker, so the 50Ω impedance spec is not dead on anyway. Very often RG59 will work fine as antenna cable for wireless mics, it often has less loss than RG58 which is 50Ω. It has more loss however than good antenna cable.
For IEM transmitters the antenna/cable combination is much more important to keep at 50Ω.
Mac
I recently heard that the center-pin and center-pin socket of the BNC connectors are slightly different for 50Ω and 75Ω, meaning that a 50Ω patch panel will have a lesser connection after someone has used 75Ω cables on it.
Does anyone know if there is truth to this claim?
-
I recently heard that the center-pin and center-pin socket of the BNC connectors are slightly different for 50Ω and 75Ω, meaning that a 50Ω patch panel will have a lesser connection after someone has used 75Ω cables on it.
Does anyone know if there is truth to this claim?
That's incorrect, 50 and 75 ohm center pins are the same diameter, and the connectors can mate without damage.
-
I recently heard that the center-pin and center-pin socket of the BNC connectors are slightly different for 50Ω and 75Ω, meaning that a 50Ω patch panel will have a lesser connection after someone has used 75Ω cables on it.
Does anyone know if there is truth to this claim?
from Wiki: "The different versions are designed to mate with each other,[2] and a 75 ohm and a 50 ohm BNC connector which both comply with the 1978 standard, IEC 169-8, will mate non-destructively. At least one manufacturer[9] claims very high reliability for the connectors' compatibility.
At frequencies below 10 MHz the impedance mismatch between a 50 ohm connector or cable and a 75 ohm one has negligible effects.[10] BNC connectors were thus originally made only in 50 ohm versions, for use with any impedance of cable. Above this frequency, however, the mismatch becomes progressively more significant and can lead to signal reflections."
...Type N connectors are another story
-
... It is now in the hands of my client to determine if they want to pay the extra $220 for the 2) 25 ft antenna wires and the 1/2 wavelength antennas to replace the 1/4 wavelengths that are stock on the BLX system...
Had to use the snark filter to read this thread.
I'm glad you figured out that point of using 1/2-wave antennas for remote mounting. 1/4-wave only works when there's a ground plane -- typically the case of the receiver. If you hadn't said it I would've.
-
from Wiki: "The different versions are designed to mate with each other,[2] and a 75 ohm and a 50 ohm BNC connector which both comply with the 1978 standard, IEC 169-8, will mate non-destructively. At least one manufacturer[9] claims very high reliability for the connectors' compatibility.
At frequencies below 10 MHz the impedance mismatch between a 50 ohm connector or cable and a 75 ohm one has negligible effects.[10] BNC connectors were thus originally made only in 50 ohm versions, for use with any impedance of cable. Above this frequency, however, the mismatch becomes progressively more significant and can lead to signal reflections."
...Type N connectors are another story
Hi Tim.
Thank you. Any chance you could pass along a link to the article? I would like to show it to someone else :).
-
Had to use the snark filter to read this thread.
I'm glad you figured out that point of using 1/2-wave antennas for remote mounting. 1/4-wave only works when there's a ground plane -- typically the case of the receiver. If you hadn't said it I would've.
Yeah, I couldn't get the snarkfest-reasoning, either.
Regarding the 1/2- vs 1/4-wave: Is this true for IEM transmitters as well?
-
Updated:
I took my SLX unit and duplicated the placement and usage area. One block wall at all times and 2 block walls at other times. Exterior building walls max at about 135' and I went to extremes in all directions. Orientation of the receiver and placement within the closet made no difference. Standing 130' away in the electrical room with 3 step-down transformers (480 - 240-120) between me and the receiver cause no problem.
The one issue that could play a role (I have contacted Shure tech support, but not heard back)... the SLX transmitter is 30mw, while the BLX is 10mw.
Does anyone want to make a prediction on the answer (if the lower output power is a problem)?
David
-
All antenna's require a reference to ground in order to perform properly. The wave length of the antenna will determine antenna efficiency and gain, plus even more important to proper operation impedance and resonance.
The best ground will be equal to the antenna resonance (1/4, 1/2, full wave length). The antenna will also perform differently if the ground plane shows as vertical or horizontally aligned with the transmitting element.
I have always felt that a simple understanding of antenna theory (dipole) would help most people understand many of the basic questions asked about proper operation.
Using a dipole, an antenna anyone can build using two (2) pieces of wire and a cable any antenna questions regarding performance can be answered. Note that a horizontal dipole will perform as a directional element with the largest lobes off of the end, and that a vertical dipole will perform as an Omni directional antenna, but with lower gain characteristics. Take time to read at the link below for self satisfaction.
http://www.antenna-theory.com/antennas/dipole.php (http://www.antenna-theory.com/antennas/dipole.php)
Bob L. - N1BRH
-
Updated:
I took my SLX unit and duplicated the placement and usage area. One block wall at all times and 2 block walls at other times. Exterior building walls max at about 135' and I went to extremes in all directions. Orientation of the receiver and placement within the closet made no difference. Standing 130' away in the electrical room with 3 step-down transformers (480 - 240-120) between me and the receiver cause no problem.
The one issue that could play a role (I have contacted Shure tech support, but not heard back)... the SLX transmitter is 30mw, while the BLX is 10mw.
Does anyone want to make a prediction on the answer (if the lower output power is a problem)?
David
I have contacted people in Europe using a 10mw transmitter. The antenna is more important than the power put to it.
-
I have contacted people in Europe using a 10mw transmitter. The antenna is more important than the power put to it.
10mw Boston to Europe? Wow! CW QRP? Please share details of your rig and methods for that!
-
10mw Boston to Europe? Wow! CW QRP? Please share details of your rig and methods for that!
That was 25 years ago Jason. 10 meter band, Cushcraft A4 at 75', the rig was a Heathkit or homebrew I think, and yes, CW QRP. I have not been active in about 15 years since a snow storm took down both of my towers.
The antenna was of course the reason for the contacts. The A4 has a forward gain of 8db minimum.
-
Looking at a Shure BLX24 or 24R system for an install. It specs as 300' line of sight. I want to rack it in the audio closet. I only need to transmit 100' (absolute max), but there will be a block wall between (7' from the receiver if it makes a difference). Any hope?
Thanks
It’s getting to complicated, are you able to run a mic cable from your mixer to the transmitter that at this point it’s in the same room as the client properly attach to the top of the 7´wall, that way your transmitter is in front of the wireless mic (client) and a professional mic cable will do the job of an extension to the mixer, I find it very simple, but of course, that is if you can or are willing/can to do it, because remember that it will need a power source for the transmitter.
-
Don't underestimate the attenuation properties of the human body. Once you fill that room full of people, if those people are line-of-sight between the transmitter and the receiver, your RF signal may drop too low to be useful.
Is it an option to remote mount the receiver near the stage, connecting it to the mixer via balanced cable? If you don't need to babysit the receiver, that might be a better option and certainly cheaper if you already have a snake with available channels.
In one of the churches I serve we have an A/T unit (don't remember the model). With 1/4-wave antennas mounted on the receiver at desk level, with the audience between the transmitter and receiver, we were getting a lot of dropouts. Remote mounting 1/2-wave antennas resolved the issue. (Mounting 1/2-wave instead of 1/4-wave on the receiver might have resolved it, too, but we didn't try that.)
Note that the length of the antennas is going to be dependent on the frequency band your receiver is capable of using. They are not all interchangeable.
-
Don't underestimate the attenuation properties of the human body. Once you fill that room full of people, if those people are line-of-sight between the transmitter and the receiver, your RF signal may drop too low to be useful.
Is it an option to remote mount the receiver near the stage, connecting it to the mixer via balanced cable? If you don't need to babysit the receiver, that might be a better option and certainly cheaper if you already have a snake with available channels.
In one of the churches I serve we have an A/T unit (don't remember the model). With 1/4-wave antennas mounted on the receiver at desk level, with the audience between the transmitter and receiver, we were getting a lot of dropouts. Remote mounting 1/2-wave antennas resolved the issue. (Mounting 1/2-wave instead of 1/4-wave on the receiver might have resolved it, too, but we didn't try that.)
Note that the length of the antennas is going to be dependent on the frequency band your receiver is capable of using. They are not all interchangeable.
This a 100' x 100' room. Estimated max occupancy is 120-ish and dispersed pretty evenly, so a mass of bodies between the mic and receiver is extremely unlikely.
Are you saying that, if the reception is sub par, I should try just the 1/2 waves alone and only buy the wire and brackets if needed? That would save about $150.
-
Why don't you test the install first, and then get back with any issues you may have. Put the antenna's up high above peoples heads and the body count won't mean much if anything at all.
-
Why don't you test the install first, and then get back with any issues you may have. Put the antenna's up high above peoples heads and the body count won't mean much if anything at all.
Bob,
yes, the receiver will be about 6 ft up at the top of the rack. I have arranged to purchase the desired unit with the condition that it can be returned if it doesn't perform.
-
Bob,
yes, the receiver will be about 6 ft up at the top of the rack. I have arranged to purchase the desired unit with the condition that it can be returned if it doesn't perform.
6ft is not high. Many people are over 6' in shoes. Get the antenna up above people and in the same room as the transmitter.
Sent from my iPad using Tapatalk HD
-
+100 - Above their heads, line of site w/ no obstructions.
-
This a 100' x 100' room. Estimated max occupancy is 120-ish and dispersed pretty evenly, so a mass of bodies between the mic and receiver is extremely unlikely.
Are you saying that, if the reception is sub par, I should try just the 1/2 waves alone and only buy the wire and brackets if needed? That would save about $150.
I've seen it happen in a 25x50 room that seats around 100; transmitter about 30 feet from the receiver. The signal was adequate and there were no dropouts during the service, but the display indicated a fair amount of signal attenuation that wasn't there when the room was empty.
If you're remote mounting the antennas, you'll probably need 1/2-waves anyway. So you might as well get them and try them directly on the receiver; it shouldn't hurt and might make enough difference -- and certainly less expensive then adding cables & connectors.