Jump to content

Proper Plug-On Tx Boom Pole Use


WaterlooNorm
 Share

Recommended Posts

Hello. I was recently informed by a highly respected professional that connecting my Wisycom MTB plug-on transmitter to a short XLR cable connected to my boom microphone violates the antenna design commonly used in most plug-on transmitter.

 

"First, I should state that this is the incorrect use of *ANY* plug-on device; no matter what the manufacturer.  Plug-on transmitters employ dipole antennas where one of the antennas are in the transmitter itself, and the other is the microphone attached to the plug-on.  Using an XLR cable between the two breaks the connection and so you have “half a dipole antenna”;  you will not have great RF coverage."

 

I am interested in this group's perspective on topic this as I see this as a common practice.

Link to comment
Share on other sites

unless you are plugging it straight into the microphone itself, youll always have a short jumper cable between where the tx is mounted on your pole, and the mic where it sits in its suspension.
i had a very quick scan in the MTB manual and it doesnt mention anywhere how to mount it for best rf transmission, and i would expect that if it was the case that it needed to be mounted a specific way, they would be sure to mention it quite early on in the manual.

i dont know how short a cable you are planning to use, but i know many mixers who use MTB plug ons for their primary booms, and they are all connected by a short jumper cable to the mic on a suspension and i have never heard of any issues they have had with range.

 

but i also expect that if you wanted to have the transmitter at the opposite end of the pole to the microphone, you would have few issues.

there are people on here with far superior knowledge about rf design than myself who would be better able to comment on your highly respected professional's comment about every plug on devices design. i just use the stuff and trust that the manufacturers know what they are doing, especially for our little niche world, and that any product that didn't work as you would expect for the premium grade equipment we are talking about would not be worth any manufacturer bringing to market. 

which is a rambling way of saying, i bet it'll work just fine however you use it.

 

Link to comment
Share on other sites

On 12/29/2021 at 7:52 AM, WaterlooNorm said:

Hello. I was recently informed by a highly respected professional that connecting my Wisycom MTB plug-on transmitter to a short XLR cable connected to my boom microphone violates the antenna design commonly used in most plug-on transmitter.

 

"First, I should state that this is the incorrect use of *ANY* plug-on device; no matter what the manufacturer.  Plug-on transmitters employ dipole antennas where one of the antennas are in the transmitter itself, and the other is the microphone attached to the plug-on.  Using an XLR cable between the two breaks the connection and so you have “half a dipole antenna”;  you will not have great RF coverage."

 

I am interested in this group's perspective on topic this as I see this as a common practice.

Normy , I've seen your setup, a 100 meter cable is not short. 

Link to comment
Share on other sites

It will work just fine. Ignore the highly respected professional lol. 

 

It will also work fine plugged into the bottom of the pole. most pole manufacturers make an accessory bracket to do just that. It will also work clipped to your belt with 20’ of cable between the transmitter and the mic. 
 

In theory your expert might be right but in terms of practical useage he’s full of it. 

Link to comment
Share on other sites

No experience with Wisycom but lot's of real world experience with various generations of Lectrosonics plug on transmitters. I use a short jumper between the mic and the transmitter, which is attached to the pole with an ambient piece of hardware and I've made it through hundreds of different projects with no problem. As someone said above, just having the transmitter high above the obstructions does wonders for your reception. I've also on occasion seen the transmitter at the back end of an internally cabled pole (~18 feet) with the same great results.

Link to comment
Share on other sites

Here's a quote from the lectro HM manual: "An antenna is formed between the housing and the attached microphone, operating much like a dipole type. At UHF frequencies the length of the housing is similar to 1/4 wavelength of the operating frequency, so the antenna is surprisingly efficient, which helps extend the operating range and suppress noise and interference."

That doesn't imply that wisycom operates the same way but it's possible they could. However, to say that using an xlr breaks the connection so you only have half a dipole shows that they don't understand how it actually works. There is still a ground connection through the xlr to the microphone which will load the opposing end of the antenna. In theory the length of the cable would affect the RF performance (just like the length of a mic would as well) but in practice you'll have RF trouble with your talent bodypack transmitters long before a plug-on transmitter mounted on a pole, provided the frequencies are clear.

Link to comment
Share on other sites

7 hours ago, Derek H said:

It will also work fine plugged into the bottom of the pole. most pole manufacturers make an accessory bracket to do just that.

It does. There's a slight mechanical flaw though, I believe with battery contacts/spring tension, if it is mounted with the XLR pointing to the foot of the pole. 

When you set the boom on the ground not gently enough, or hit some obstacle when moving backwards the unit just turns off and needs to boot again.

I've experienced this with quite a few (but not all) MTB units on my Ambient boom with the QALP. Not a big issue, since you learn quickly how to set it down.

Link to comment
Share on other sites

20 hours ago, MartinTheMixer said:

Normy , I've seen your setup, a 100 meter cable is not short. 

You must have the wrong Normy 😉

 

I'm using an 18" low-profile cabletechniques mounted with a rycote at the top of the boom.

19 hours ago, BAB414 said:

No experience with Wisycom but lot's of real world experience with various generations of Lectrosonics plug on transmitters. I use a short jumper between the mic and the transmitter, which is attached to the pole with an ambient piece of hardware and I've made it through hundreds of different projects with no problem. As someone said above, just having the transmitter high above the obstructions does wonders for your reception. I've also on occasion seen the transmitter at the back end of an internally cabled pole (~18 feet) with the same great results.

Thank you. My setup is similar and not experienced any RF issues although I may not have been stressing the RF enough to notice a difference.

15 hours ago, Patrick Farrell said:

Here's a quote from the lectro HM manual: "An antenna is formed between the housing and the attached microphone, operating much like a dipole type. At UHF frequencies the length of the housing is similar to 1/4 wavelength of the operating frequency, so the antenna is surprisingly efficient, which helps extend the operating range and suppress noise and interference."

That doesn't imply that wisycom operates the same way but it's possible they could. However, to say that using an xlr breaks the connection so you only have half a dipole shows that they don't understand how it actually works. There is still a ground connection through the xlr to the microphone which will load the opposing end of the antenna. In theory the length of the cable would affect the RF performance (just like the length of a mic would as well) but in practice you'll have RF trouble with your talent bodypack transmitters long before a plug-on transmitter mounted on a pole, provided the frequencies are clear.

Yes, I believe this is the same for the MTB but your explication helps clear this up.

Link to comment
Share on other sites

I hooked up three configurations and measured the output with a spectrum analyzer. Using an MKH 416 connected to an SKP 500 here are the results:

 

SKP 500 directly connected to the MKH 416, -51db

SKP 500 connected to a short stub (cable included with Rode windshield), -44db

SKP 500 connected to a boom's internal cable at about 48" length (graphite boom), -46db

 

Best results then is the short stub.

 

I didn't think of trying the internal cable stretched out.

Link to comment
Share on other sites

On 12/31/2021 at 6:48 PM, Paul F said:

I hooked up three configurations and measured the output with a spectrum analyzer. Using an MKH 416 connected to an SKP 500 here are the results:

 

SKP 500 directly connected to the MKH 416, -51db

SKP 500 connected to a short stub (cable included with Rode windshield), -44db

SKP 500 connected to a boom's internal cable at about 48" length (graphite boom), -46db

 

Best results then is the short stub.

 

I didn't think of trying the internal cable stretched out.

That's very helpful - Thank you Paul!

Link to comment
Share on other sites

Join the conversation

You can post now and register later. If you have an account, sign in now to post with your account.
Note: Your post will require moderator approval before it will be visible.

Guest
Reply to this topic...

×   Pasted as rich text.   Paste as plain text instead

  Only 75 emoji are allowed.

×   Your link has been automatically embedded.   Display as a link instead

×   Your previous content has been restored.   Clear editor

×   You cannot paste images directly. Upload or insert images from URL.

 Share

×
×
  • Create New...