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José

Setting wireless lavs for dialog (mic level vs. line) what's your preference?

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What are the advantages of setting wireless mikes to line level vs. mic when it comes to dialog scenes? My preference is to always set them to mic for any show where I am the main mixer. About 60% of the work I do is in reality TV and when I day-play for other reality shows that have their workflows already established, I've noticed that most of them have their mixers switched to line level for their wireless receivers. I am not one to disturb another show's audio workflow, and so I will mix the wireless mikes at line level for the whole day--No problem.

 

However, what my ears tell me is that low level passages of dialog do sound very faint compared to when wireless mikes are at mic. The only thing I can fathom is that line level may help in mixing audio levels for talent that may shriek and yell a lot.

 

If the sound mixers in the scripted field can chime-in on this also, that would be great.

 

 

Thanks in advance!

 

 

 

 

 

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i'm not sure I understand why people gain down their Rx's to mic level. on the Lectro SRb's at least, the max output of +5 is what they run internally, anything lower is just attenuating the full signal, which you'll have to gain up later with your mixer preamp.

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Most cameras that I've measured have much better s/n through their line-level input setting than through the mic-level setting.

 

So if you're connecting the wireless receivers to cameras (either from the mics or from a camera hop), line is going to be better.

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I'm on the other side of the coin. After adjusting the transmitter gain to the output signal of the lavalier mike (to just where the transmitter will seldom clip), why increase the signal within the receiver all the way to max at +4? You add a lot of unnecessary gain noise right there.

 

Why not preserve the low level signal by adjusting the receiver's output level to where it's suitable for your mixer at mic level range? From there you have complete control of how little or how much gain you need in bringing up or attenuating down the signal?

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José - people do differ on this issue. It has been discussed here a great deal.

The general view is that it is better to utilize a strong signal (line level) in a bag or cart or direct to camera situation, where low-level noise can be introduced into the system via power issues or RF interference. At mic level, this can be above the noise floor.

While you certainly can attenuate your receivers to mic level giving you a ton of gain on your mixer, it really isn't necessary if you are using quality mixers and recorders.

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i'm not sure I understand why people gain down their Rx's to mic level. on the Lectro SRb's at least, the max output of +5 is what they run internally, anything lower is just attenuating the full signal, which you'll have to gain up later with your mixer preamp.

That's been true with Lectrosonics' receivers as far back as I'm aware.

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I'm on the other side of the coin. After adjusting the transmitter gain to the output signal of the lavalier mike (to just where the transmitter will seldom clip), why increase the signal within the receiver all the way to max at +4? You add a lot of unnecessary gain noise right there.

Why not preserve the low level signal by adjusting the receiver's output level to where it's suitable for your mixer at mic level range? From there you have complete control of how little or how much gain you need in bringing up or attenuating down the signal?

That might be valid thinking if most wireless systems worked that way -- but they don't. Read Max's post.

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I concur w/ Phillip. Why run thru 2 mic pres instead of one.

 

However some wireless mic receivers do not have high enough output to drive a +4dB (nominal) line or were designed to output mic level. For example the G2/3 portable receiver can be little anemic feeding some +4dB inputs, so in some instances mic level may be better, if one has decent mic pres. I use line level 99% of the time however.

- I'm not sure the OP understands the transmitter gain structure either.. obviously mic level w/ a lavaliere mic and set to optimum settings , and most cannot be changed in the middle of a scene and many require removal from the talent

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I am completely open to criticism for my preference of mic level over line level for my wirelesses. It's all constructive.

But Rick! What does optimum settings and removing lavs in the middle of a scene have to do with gain structure at the transmitter? You adjust the gain at the transmitter to the relative output level of the signal coming in. And it's all dependent on how that source is wired. If it is wired at line level, then I'll let it pass on through the rest of the way at line.

I get the argument that once you achieve line level, maintain line level through device to device through the rest of the signal chain, but not with my receivers. I rather keep mic level until the signal arrives at the preamps of my NOMAD mixer. And by the way, Leaving them at mic level before mixer sounds excellent.

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Jose, I don't think you have it yet. Lectro receivers operate at line level (+5 out). I know you think you are leaving everything at mic level all the way to the Nomad, but what you are really doing is taking a line level signal from the Lectro receiver, attenuating it down to mic level, and then back up again with your Nomad preamps. 

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Please re-read what Max Hirtenstein and others have said. Somewhere there is a fundamental mis-understanding regarding gain structure and wireless microphones. I believe that you arrived at your "preference of mic level over line level" to achieve some goal regarding noise floor but it just doesn't work that way. 

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OK I looked at the schematic and it does show the amplifier before attenuators at the output. So yes, I see line level. I admit I'm wrong, I will put it to rest. Thanks!

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I prefer running my Lectro's at mic level into my mixer too. I don't care about the specs, to my ears the audio behaves in a better manner when I do it this way. It just sounds better to me...

Actually, I run my Lectro's at -24, so somewhere in between I guess

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Jose: " You add a lot of unnecessary gain noise right there...I rather keep mic level until the signal arrives at the preamps of my. "

while this has been covered here, it has not been discussed recently; this is basic gain staging, and, Jose, if you ask us about it, then please do not dismiss the responses, especially since Jay Rose has actually written the book and  sounds like you need to study it www.dplay.com.

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Most importantly, if we are talking about Lectrosonics, they are built to output line level. Outputting mic level is padding down the signal so your mixer/recorder has to then make that up. Some people might like the sound of their board's preamps, but you are knocking down a signal just to boost it back up. In the days of cabled boom (sic), that maybe made sense so all mics went through the same preamps and had a similar coloring of the signal.

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I am completely open to criticism for my preference of mic level over line level for my wirelesses. It's all constructive.

But Rick! What does optimum settings and removing lavs in the middle of a scene have to do with gain structure at the transmitter?...

 

José, just so we're on the same page (and sorry if I missed it earlier in the thread), but what model transmitters and receivers are you using?

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I'm on the other side of the coin. After adjusting the transmitter gain to the output signal of the lavalier mike (to just where the transmitter will seldom clip), why increase the signal within the receiver all the way to max at +4? You add a lot of unnecessary gain noise right there.

 

Why not preserve the low level signal by adjusting the receiver's output level to where it's suitable for your mixer at mic level range? From there you have complete control of how little or how much gain you need in bringing up or attenuating down the signal?

Hi José,
OK, let me be blunt. (At my age, I've both  earned it and the right to be cantankerous.) Repeat 3 times: "Line level is better than mic level."  "Line level is better than mic level." "Line level is better than mic level."
 
1. Taking a line level signal and lowering it to mic level, then gaining it back up to line level again is poor gain staging practice. Inside any receiver of any brand, be it FM demodulation or 1's and 0's, the derived audio signal is close to or at line level in the internals of the system. Having mic levels at the transmitter does not mean you have mic level signals in the receiver. In the bowels of the receiver, the signal is at or close to line level. There is no noise added by "running" the receiver at line level. The noise is already there from the demodulation process. Attenuating the signal to mic level may or may not add much more noise and distortion but leaving it at line level absolutely won't add garbage. This isn't just true for Lectro but for any well designed system and that is what you all buy.
 
2. Any well designed recorder or mixer can gain line level signals up or down just as well as mic level signals.
 
3. Line level signals are 40 dB (+ or -) more immune to ground loop noise or hum loop, RF interference, digital transmission artifacts from the AM component and whatever other weird electrical stuff that can be cooked up in a bag with multiple switching power supplies on different frequencies. Many a noise problem that was solved with isolated supplies (our ISO9Volt) or premium transformers could have been resolved with 40 dB more signal, i.e., line instead of mic level.
 
4. Current wireless systems have a dynamic range of 100 to 110 dB. Since the noise floor of any audio input stage cannot be better than minus 132dBm at room temperature, any receiver audio output signal below -30dBm will degrade the SNR of a modern receiver. For instance a low mic level signal at-60dBm will degrade the SNR to 72 dB. If the audio input stage is a more common -127 dBm, the SNR is now 67 dB. This is just thermal noise in the audio input stage and cannot be designed out. Hum, RF, ground loop, etc., just makes the situation worse than this best case noise figure.
 
OK Larry, if line level is so great, why do you even offer mic level outputs on your receivers?
Because some equipment is mic level only, some customers want to be able to switch from a microphone output to a receiver output quickly without resetting levels and some customers are more comfortable with mic levels. Just be aware "Line level is better than mic level." Wash and repeat.
 
Best Regards,
Larry Fisher
Lectrosonics 

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5.  Mic level is closer to the thermal noise of your circuit components (assuming both are signals are at the same ambient temperature).

 

I mean, if you're going to be complete...

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Great advice from Larry. I wish a short version of this was in all the Lectro receiver manuals! As it stands, the usual thing in the manuals is that it explains how to change the RX output level "for precise level matching with other equipment." I would add, "Under normal circumstances with professional line-level equipment, this should be left at +5dBm."

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I have taken in the discussions well. I will break my bad habit and begin working at line level at +5 on my receivers with line-in as opposed to mic-in to my mixer. I will kiss my mic level -25 settings goobye no matter how good  it may have sounded to me.

 

OK Thanks guys!

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It's possible that you have encountered a psychoacoustic phenomenon. Re-boosting the signal from mic level probably introduced a tad bit of additional noise, which it has been shown through blind testing, the brain may interpret as improved high frequency response.

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