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Audio-Technica Wireless Mics and Compressors

Discussion in 'Sound, Music, and Intercom' started by falcon, Mar 5, 2005.

  1. falcon

    falcon Active Member

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    We have rented 5 Audio-Technica 600 series wireless headset mics. We have 4 of them working perfectly, but the 5th one is causing us problems. It's jumping recievers, causing feedback, there is tons of interferance on the line and so forth. Any basic problem that you can encouter with them, it probably has done that. Now, thes mics work on the the 400 mhz frequencies and for anyone who knows waht they are, they are all A band frequencies. Each reciever/transmitter can be set to one of ten channels and we've tried them all, excluding the ones that the other 4 mics are on, of course. Does anyone have any ideas as to what can be going on, or did we just get a really crappy mic mixed in with the good ones?

    On another note, I have 6 other wireless mics (I can't remember the brand, but I think we got them from Rockford...) that we have hooked up to compressors and sometimes, the mics don't work, but it works when I remove the compressor from the channel. How do I make it work with the compressor? and if anyone can give me the basic of how compressors work and how to use them properly, let me know.
     
  2. wolf825

    wolf825 Senior Team Emeritus Premium Member

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    Hiya falcon,

    Couple things to check with your AT--first off on the Audio Technica 600's, its a NON DIVERSITY system. It may have two antenna's but its not a diversity system (and you can check with AT on the website for that too)..so its very suceptible to frequency interferences. Second--its a lowband UHF--also suceptible to problems. Since you have gone the route of changing frequencies and still have probs, my best guess without seeing it is that the reciever or transmitter is having frequency issues that are not locking. So--the way to see which it is, is to assign a different beltpack to that problem reciever, and then assign the problem beltpack to a different reciever etc--see if the problem carries to another unit or beltpack you know works fine. That narrows it down... If it carries to another reciver--then your beltpack transmitter is the problem....if the problem stays with the reciever no matter what different transmitter you try--then the reciver is at fault. This way you at least can narrow down the problem. You can also try relocating the reciever away from the other units and see if that helps it. With those 400mhz range frequencies on a non diversity system--its gonna be hard pressed to not be suceptible to interference--and even crosstalk or interference between like-units.
    Another thing to check that is a common problem--which can be a possible problem in your situation too (again--I am not there to SEE what it is actually doing), is the SQUELCH control for that unit. It should be a little knob or hole for a screwdriver in the rear of the reciver unit. Turn it to adjust the squelch--which in a broad nutshell of an explanation will help you "tighten up the transimission connection" between the transmitter and reciever. Basically, when the unit is not recieving--it will not pick up or make any "noise". See how that works and post your answers and I or someone else will gladly help out..and others may have other info for you to try..

    On your other note about compressors--what are you trying to achieve with the compressors on the wireless?? Most compressors are great for helping with channel control and level control--however they will not help you if your mic's are clipping, distorting or being overdriven before they even get to the compressor. Also to answer your quesion--how are your compressors hooked up to the wireless mics? Are they INSERTED using an insert cable into the wireless channels? If so--your insert cable may be backwards or not be a real insert cable--a common mistake. Also--check your connections--make sure if you are going from an output that you maintain whether it is balanced or unbalanced--XLR or TRS / TS type of phono plug. You cannot mix and match when it comes to those cables when coming out of a balanced output and you use a unbalanced cable.

    If thats not it, then answer this--Are your wireless run into the compressors first--and then into a console channel? If so--bad idea and it won't work or if it does will be intermittent and crappy, because of the extremely low signal... You need to run the signal from the reciever into the console first, because the console has a PREAMP which in a nutshell changes the voltage in an input into a usable voltage that most other electronic equipment can then do something with. The Output voltage from most outboard equipment like CD players, Tape Decks and Wireless Mics are very low voltage levels and do not travel more then 10 feet before degrading into unusable garbage..they NEED a pre-amp to boost and make them into as usable voltage level.


    Now to the Second part of your question....

    Compressors 101... Compressors are great little tools for useing to help control an input level to not go above a set level. It does this by compressing the signal--which if you think about water flowing in a trough, its like daming up the water flow with your hand so that only a small part of the water passes--the rest builds up before its released when it reaches your hand. So think of a compressor as your hand in the water. A compressor can be used for simple compression on a whole PA system or a single channel, and it can be used for tricks like "Ducking" and so on (see below). But overall a compressor can help with a Sound System or channel input to keep levels even or balanced in peaks and dips and from overdriving speakers--however over-use or poor settings of comprerssors can be just as detrimental to a speaker as the distortion is because too much compression can cause distortionon. It also causes what is called "breathing" or "pumping"...a notable sound where the levels go from being unclear and "muddy" to suddenly being loud and clear on lesser levels. A compressed signal HAS to release that compressed signal--it cannot hold onto it forever or just make it go away.. so the trick and problem most folks face is setting the compressor properly for the application. You can HEAR compression if its set hard or the signal is too strong at a point. It sounds like the sound is being pressed down.. For example: If you get a copy of Whitney Houston's "I Will Always Love You" song you can HEAR the compressor kick in on her strong vocal notes..and its not much around this because her voice is so powerful.

    The Settings of a compressor are the hardest to figure out. You typically have basic settings in cheap units, like a THRESHOLD , and ATTACK and a RELEASE and a RATIO...and on some of the cooler pro compressors you will have more settings to adjust like Frequency/shelving, Peak setting, Gate, Expander, Hard Knee/Softknee--also known as Overeasy (dbx) and many others. Here is a quick explaination of these basic knobs....

    THRESHOLD is the level at which the input signal activates the compressor. Ideally, you want the compressor to barely click on or not move at low and optimum sound levels, and only click on when the levels peak. Low thresholds will compress a LOT of signal that is passed into the unit, and higher thresholds will allow more signal to pass before it compresses. There is no overall good threshold setting because signals vary so much..its the one true knob you have to play with and learn to get right..

    ATTACK: this is how fast your compressor kicks in to a signal that has past the threshold level. Sometimes a fast attack is desired--other times a slower attack is desired to lessen the "sound" of the actual compression so its not so fast or "overeager" sounding to click the compressor. Typically--a FAST to Medium fast attack is what works 95% of the time. Depends on the sound and reaction of your compressor and how the threshold is set...

    RELEASE is sort of the opposite of attack--its how fast the Compressor RELEASES the compressed signal. If you release too fast it can sound like pumping if the compressor is triggered a lot. If you release slowly however you can end up adding an extra "harmonic" or muddyness to an otherwise clear signal.. Generally--a medium release works 90% of the time so as not to be noticable.

    RATIO is the setting displayed by a ratio comparision--a 1:1 or 1 5:1 or a 10:1, INFINITY:1 and so on.. You can have as manay as 10 or 15 different ratio settings on a compressor--including Infinity. (the sign for Infinity is an "8" on its side) What this ratio does is tells the compression ratio, or amount of db that is compressed, when the compressor is triggered. For example: a 4:1 ratio will compress the signal 4db for every 1db over threshold. a 10:1 will compress 10db for every 1db over threshold, and so on. Infinity means no matter how much goes over the threshold it will not get beyond 1db louder. The more compression you set it for, the harder and more noticible the compression can be. The less compression you set, the opposite happens--but it may also not be ENOUGH compression for a very large peak. The higher the compression ratio the more you are making your compressor into a LIMITER--and that is a device that LIMITS the signal--so the less signal will go pass the compressor after threshold is reached. On a poorly set or very LOW threshold, this will make a signal sound like MUD if it is too heavy in saturation..as all the compressed sound will build up and release 1/2 or 2 seconds later or whatever and that is exponentially to the input amount. So try to avoid too much compression--its a killer and can cause mud and distortion. A Good overall ratio setting is 2:1 or 4:1 for about 90% of the things you will do as a sound guy.. Its great for Vocals, drums & cymbals (4:1 is OK for most drums if the threshold is right--sometimes you need 6:1 for drums and a really wild drummer), horns and so many other things. It sounds more natural on peaks--and is less noticble by an ear.

    Again--the Threshold is THE KNOB you must learn to use properly... You can use the settings I have suggested above for the others--but the Threshold is the one you HAVE to learn how to set yourself.. ALL the above settings must be set to work together or you achive nothing in compression.. A great threshold setting won't do squat if you don't have a ratio or attack/release setting done. A great Ratio or attack or release won't do squat if you don't have a good threshold level for the signal. A good way to play with and learn what a compressor does is to sit down with a CD or Mic, a console and PA or headphones, and play with one. Set a low threshold, input your sound (mic or CD or instrument) and adjust the Attack and Release and Ratio and LISTEN to the differences each one does.. Then Go about and do the same to the other knobs. Only after you LISTEN and Learn what compression sounds like will you be able to understand how all the other knobs work together..and then you will want MORE knobs to play with like Peak and Overeasy and Frequency/Shelving and so on. I will explain what those and other fun knobs you can find on compressors can do later on if you want.. If you have a Compressor GATE set up--a comp and a gate in a single unit--then you will have evcen more knobs and things to set and playwith--including another GATE Threshold knob that works opposite how a compressor threshold works.

    Thats its for Compresors 101 in a rough nutshell..... Oh yea--DUCKING with a compressor is setting the compressor to use a signal as its source for threshold, and another input signal for the trigger--which will then DUCK down the original signal. This is mostly used in recording and for commercials. If you hear music in a commercial and then it dips down immediately when the voice talks and pops back up when the voice stops talking, thats DUCKING.

    well hope this helps ya.. Others will come and fill in the gaps I have left and I hope they will offer their opinion and insight as well. Feel free to post back any questions or problems and I or someone else will be glad to answer.

    Cheers,
    -wolf
     
  3. wolf825

    wolf825 Senior Team Emeritus Premium Member

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    Here is a quick scan I did from the Audio Technica website--the PDF file for the AT 600 says you cannot use more then 4 of the AT 600 A band units together. You need to get B band to use more then 4 units--this tells me that the frequency settings are very broad and overlap--so this would be the source of your problem. The 5th unit is interfereing with the others and its jumping to other recievers--and when you have two same or similar-freqencies transmitting, you then get cancellation and drop out problems with the recievers. SO--You can't use more then 4 of these A band units together... Sorry...

    http://audiotechnica.com/guide/wireless/600Freeway.html

    click on the pdf MANUAL at the bottom--its on the first page under NOTE on the right side. Take the 5th unit back and ask for a B band unit if they have one, or your money back...and print out the PDF so if they give you any crap you can tell the renter (who should have KNOWN this) that they are morons and rented you the wrong gear...


    cheers....
    -wolf
     
  4. falcon

    falcon Active Member

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    I think I should be okay with the info about the compressors, I think they guy said that there was a gate in there too, but I'm not too sure. And as for the mics, I will call them on Monday when they are open and get it changed.

    Thanks
     
  5. Peter

    Peter Well-Known Member

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    wolf: Thank you VERY VERY much for that little tutorial on compressors! I have only messed with them a little bit (and only in software that i have, we dont have any physical ones to use in our Aud) and that discription is sure to help alot. Thanks!
     
  6. cutlunch

    cutlunch Active Member

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    Falcon if there is a gate in the compressor this can cause you problems by having the signal threshold set to high so not letting the signal from the microphone through. The easiest thing to do is download the manual for the compressor it should show the proper connection method and settings. How many compressors did you get? I don't know if I would use a compressor on each mike. Since you seem to have a total of 11 wireless microphones does this mean that you are not swapping mikes at all during the show? I would consider putting the wireless mikes on a sub-group and just compressing the sub-group.
     
  7. mbenonis

    mbenonis Wireless Guy Administrator

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    Gates can be your best friend or your worst enemy, depending on whether they are set up properly. So let's talk about gates.

    GATES 101

    A gate is a pretty simple concept to understand. When the signal passes through a gate, if it is below a certain THRESHOLD, it is cut off entirely*. Otherwise, it is allowed to pass through untouched. This can be helpful for a couple of reasons. First, if a mic is left open, but nobody is talking into it, it is turned off by the gate and therefore is less susceptible to feedback and won't cause comb filtering (two mics picking up the same sound at different distances; this causes it to sound really bad). Also, gates can make hiss in a tape less noticeable by cutting it when there is no other sound coming from the tape. You can think of it as a person constantly riding the mute button for you.

    The trick is to set the Threshold properly. You want to set it so that the softest sound a person will make will pass through, but anything under that is cut off. This is done either during a rehearsal or during a mic check.

    Now, as wolf said, you shouldn't connect the wireless mic outputs directly into the compressor, UNLESS the output is a line level signal. This is determined by a switch on the back of most units. I've actually moved to sending line level signals simply to reduce the chance of getting interference (I think we may have a bad cable somewhere in our system).

    *OK, I lied. Chances are, it's not really a gate, but an expander. If this is the case, the expander reduces the sound by a certain ratio below the threshold. For instance, if one dB of sound enters, its stretched to, say, 2 dB. But this has the effect of cutting off the sound below a certain level anyway. If any of this is incorrect, someone please correct me.
     
  8. mbenonis

    mbenonis Wireless Guy Administrator

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  9. falcon

    falcon Active Member

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    well, I just got back from rehearsal and I have to say, the 11 mics are working perfectly with a few exceptions. The last mic, we are switching for another Shure ULX mic, so that should be perfect for me.
    I took all the info about compressors that you guys gave (thanks alot for that) and managed to make 5 mics sound way better.
    The last compressor we have is hooked up to the one mic that was causing me trouble, for some reason it was distorting the vocals. I played around with the compressor but couldn't get the distortion out and when I unplugged the compressor, it helped a little but not alot. I think I'm going to have to keep that actor after tomorrow's all day rehearsal work it out. Anyway, I gotta finish my homework and these cue sheets.
     
  10. wolf825

    wolf825 Senior Team Emeritus Premium Member

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    If you have distortion on a mic and have removed the compressor, then your mic may be distoring at the mic itself--check the sensitivity or GAIN setting for that mic and turn it back some and that may fix your problem. If it does not--then your mic element may be damaged... If its a wig mic or lavalier style, it can easily get damaged by moisture (sweat) and a short blast of canned air can fix that, or it may permanently be damaged--actors are notorious for using hairspray after being mic'd and that hairspray acts like a stiffiner on the mic element--and there is not a thing you can do to fix it once that happens..the mic has to be replaced. Letus know how things go and folks here can help further..

    -wolf
     
  11. wolf825

    wolf825 Senior Team Emeritus Premium Member

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    U R very welcome Peter..

    Mbenonis did a great explanation of gates and some good links to check out too for more info..those articles do a lot more explanation then I have time to write..


    -wolf
     
  12. Peter

    Peter Well-Known Member

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    yes, ditto what I said to you about Compressors to Mbenonis about Gates! Cubase comes with a plugin that has all kinds of compressors and gates and Limitors (something that has not really been mentioned arrund here yet) and I have had abunch of fun playin with them all. Thanks to both of you for the helpful pointers!
     
  13. mbenonis

    mbenonis Wireless Guy Administrator

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    Watch the audio level meter on the receiver itself. If it goes into the red (clips), then you need to turn down the gain on the transmitter pack.
     
  14. soundman1024

    soundman1024 Active Member

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    That was a good way to explain compressors. Well said.
     

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