WaterlooNorm Posted December 29, 2021 Report Share Posted December 29, 2021 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. Quote Link to comment Share on other sites More sharing options...
rich Posted December 29, 2021 Report Share Posted December 29, 2021 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. Quote Link to comment Share on other sites More sharing options...
jason porter Posted December 29, 2021 Report Share Posted December 29, 2021 I've always had amazing range on my MTB plug on, even at the lowest RF power setting. I think that getting any plug on Tx up and above or away from any water bags (bodies) more than compensates for any compromises in the antenna. Quote Link to comment Share on other sites More sharing options...
MartinTheMixer Posted December 30, 2021 Report Share Posted December 30, 2021 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. Quote Link to comment Share on other sites More sharing options...
Derek H Posted December 30, 2021 Report Share Posted December 30, 2021 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. Quote Link to comment Share on other sites More sharing options...
BAB414 Posted December 30, 2021 Report Share Posted December 30, 2021 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. Quote Link to comment Share on other sites More sharing options...
Patrick Farrell Posted December 30, 2021 Report Share Posted December 30, 2021 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. Quote Link to comment Share on other sites More sharing options...
DanieldH Posted December 30, 2021 Report Share Posted December 30, 2021 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. Quote Link to comment Share on other sites More sharing options...
WaterlooNorm Posted December 31, 2021 Author Report Share Posted December 31, 2021 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. Quote Link to comment Share on other sites More sharing options...
Izen Ears Posted December 31, 2021 Report Share Posted December 31, 2021 Does a mic cable’s impedance add some resistance? Which would mean what, a tiny bit of range affected on one antenna? I have run those Lectro plug on HMs on 100’ XLR and it worked great. Great thread! Dan Izen Quote Link to comment Share on other sites More sharing options...
Paul F Posted December 31, 2021 Report Share Posted December 31, 2021 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. Quote Link to comment Share on other sites More sharing options...
WaterlooNorm Posted January 4, 2022 Author Report Share Posted January 4, 2022 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! Quote Link to comment Share on other sites More sharing options...
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