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glenn

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About glenn

  • Birthday January 1

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    New Jersey
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    Inventor, Electrical Engineer, Mechanical engineer, GUI designer, Artist, Comic
  • Interested in Sound for Picture
    Yes

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  1. Tips to getting the best distance from your wireless transmission Never use amplified antennas. They can easily create intermodulation interference that the best receiver front ends can not filter out. Even if you use one with a RF pad set to Zero it is a problem if the amp is still in line. Always use passive directional antennas with low loss coax. Use LMR-400 coax for longer runs, it has a loss of 3dB per 100 foot. This is more than acceptable as to not affect range and to get the best performance from the receivers front end filtering. Digital wireless needs a linear transmission path. Amplified antennas are very non linear when overloaded and sometimes without overload. If running 10 FT of coax you can use high loss coax as the loss is 1/10 of the 100 foot run. 10dB loss per 100 feet is fine on a 10 FT run. Using directional antennas is the best way to get the greatest distance and to minimize interference. You can double the distance your wireless will work and minimize interference from interfering walkies, cell phones and television stations if they are coming in from different directions like from the back or the sides of the antenna. If you use 2 shark fins for receiving, separating them more than about a foot is unnecessary. Mount them both in vertical orientation and parallel to each other. If using a fin for IFB transmission, mount it below the 2 receiving antennas by a few feet (2-3) for isolation from the receiving antennas. Do not mount it at the same height as the receiving antennas as it will couple more noise into the receiver than it needs to. This trick can lower RF receiver noise by 9dB. If you have a choice, stay away from dipoles. "Shark fins" Log periodic antennas are much better for digital modulations like Zaxcom Wireless and are directional. Log periodics tend to minimize the nulls that can happen as mics move through free space as their multiple elements even out the signal. Do not use a dipole with a log periodic antenna for antenna diversity. Using a good antenna with a bad antenna is not diversity, its a problem. Get your antennas up in the air as high as possible. This will help to get obstacles like people out of the way and guarantees you that someone near the sound cart can not get closer to the antenna than the height of the antenna helping to prevent overload and intermodulation. 10 feet or higher is best. With Zaxcom wireless use ZHD96 modulation indoors and in reflective outdoor spaces. Use XR in Iowa corn fields where there are no reflections. Don't keep transmitters on at your cart that are inside your receiver's filter bandpass. This can have the effect of desensitizing the receiver and make it easier to create intermodulation if there are other high power transmitters nearby. We call this near/far effect. It is much easier to go 500 feet if you do not have an actor with a live transmitter looking over your shoulder at the cart. Avoid antenna distribution amplifiers if possible. They, like amplified antennas, can cause intermodulation that can really mess up a receiver. If you must use one make sure it has a band pass filter in front of it or built onto it. Our Micplexer II has the Zaxcom flux capacitor filter that limits the bandpass to 35MHz and also has overload lights to tell you someone is looking over your shoulder with a live transmitter. Keep transmitter antennas away from direct skin contact. The body does a great job of sucking all the RF out of the air and de-tuning the transmitter antenna. Use a 1/2" diameter or better a 1" diameter foam tube to hold the antenna away from the skin if placed under clothing like on a leg or arm. If a transmitter is being used very close to the receiver like 10 feet or less use the lowest power transmitter setting. This is just good practice and can minimize interference to receivers that might pick up signals if they do not have a transmitter to listen to on their own frequencies. Our receivers can decode a signal with only 7 dB of signal to noise at a level of -100 dB noise floor. You will never be too close to a Zaxcom receiver at any power level to cause it to not decode. I have been wanting to put this out for a while. This is by no means a complete list but I hope it might prevent some bad situations as more sound mixers move from analog to digital wireless. For bag use, Keep UHF IFB transmitters at least 50 MHz away from the frequencies used for body pack receivers. If possible use a filter on the transmitter to eliminate any wide band noise that might fall into the receivers pass band. No receiver front end can eliminate the wide band noise from a transmitter located within a foot of the wireless receivers in a sound bag. This is because the transmitter noise is in the receivers pass band and can not be filtered out by the receivers front end filter. Any claim that a receiver by it self can solve this problem is sales promotion nonsense. Glenn
  2. Just saw this topic. Here are some comments. Filters should be passive devices and will not add any noise to the RF signal. Active antennas with filters are a different story as the manufactures of such devices don't tell you enough about them in most cases to be useful. The micplexer has a great filter before its buffer amp that feeds the splitters so that the output of the micplexer has only a few dB of gain with the protection of our tunable filter before the amp. Its bandwidth is about 35 MHz +/- 17.5 MHz. Do not use active amplified antennas. Use low loss coax instead . Active antennas are the industry's version of snake oil and will often do much more harm than good by creating intermodulation interference ahead of a good receiver front end that can not be filtered out. I will look for my RF tips to post here that cover a lot of this. Glenn
  3. Zaxcom URX100 IFB receivers interface with Motorola walkies and also listen to any Zaxcom bodypack or cart transmitter at the same time. It might be the bridge you are looking for. Glenn
  4. I am certain our dealers will be happy to send out a demo unit to you to get going. If you have any difficulty please call me direct I will get you hooked up. Glenn
  5. If you are looking for a new system backfocus you might look at the Zaxcom ZMT4 transmitter. It is about 1/2 the size of the A20 and will run at full power for 7 hours with a rechargeable battery. Cost to run every day is nearly Free. There are many other advantages that you can learn about on our site Zaxcom. Com
  6. That would not be possible. All audio clocks have to be locked to the transmission bit stream or bad things happen.
  7. Everything resamples the AES from a super cmit. There is no way to synchronize it with an external reference.
  8. It would be best for Simon Hayes to comment on his wired and wireless use of super cmit. We have never had anything but praise for the Super cmit/ TRX743 combination. I am sure you had a problem with something (maybe the recorder aes input?) but digital transmission of a Super Cmit with a TRX743 is a great combination and to my knowledge the only AES42 wireless microphone transmitter.
  9. Constantin: The TRX743 and TRX742 can only pass the digital output of the mic to the receiver nothing more or less. If it did not sound right then there was a problem somewhere else like in the Mic or mixer for example. Simon Hayes has been using the Super Cmit with 743 for years .Hopefully he can chime in. Also the signal can never become noisy as it is a stream of 1s and 0s. Its either there or its not.
  10. I think it might be about 24 hours. I can do a test if it need to make a decision to use it or not. Glenn
  11. glenn

    Zaxcom Aria

    I think you will find the ARIA is in its own new category of location sound mixer. Going from bag to cart with 8,12 or 16 faders with the elimination of resistive faders that are not designed for location use sets a new standard for our industry. ARIA is more than a mix surface with keyboard interface and USB port for the GUI interface. Power consumption is very location friendly at .15 amp. We will start delivering soon.
  12. There are 3 impeadace settings in the audio menu. 10K is default. 2.5K will be the lowest noise setting with a bit of low frequency roll off. 6061 will have a 10 dB higher noise floor than the 6060. For the lowest noise from the mic the 6060 is the best choice for our or anyone’s wireless. All lav mics have self noise as the dynamic range of the mic is limited to about 106 dB. Without companders or noise reduction software you eventually will hear it if you are in a quiet enough environment.
  13. The ZMT4 has been updated since it’s initial release and now lasts 7 hours with a Lav and 5 hours running a 48V mic. This time is increased with Power Roll a patented feature. I like to think of it as a no compromise transmitter that can go through the entire day with only 1 battery change at lunch. These run times are at a full 50mW power level, recording, Transmitting and receiving Zaxnet all at the same time.. Because of the efficiency heat output is almost undetectable under normal usage. ZMT4 is also about half the size of most digital transmitters.
  14. Mattias the ZMT4 runtime is 7 hours minimum at full 50mW power. It was 6 but we picked up some efficient with some hardware changes. We have had customers reporting 7.5 hours on a regular basis. This of course generates very little heat output due to the extreme efficiency. This is more important for us than others as the ZMT4 is roughly half the size of most other digital transmitter.
  15. Zaxcom products are very low power due to the obsessive need I have to use extremely high efficiency power supplies and to use the lowest power components where possible. We also use relatively low power DSP processors running our own operating system that is much more efficient than Linux or MS OS.
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