Simple Novice Question - Mic Gain on Mixer ...

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MicMaven

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Can anyone provide a 5th Grade explanation of how/when to use the Chanel Input GAIN control versus the Channel Level Control on my mixer? On my mixer, the Gain control is next to the XLR jack, and the Level control is at the bottom and grouped with EQ, Pan and and Post controls.

Almost too embarrassed to ask, as I KNOW this is a real novice question, but I have yet to find a concise, clear explanation as to how much of each to use relative to the other, and a guy has to start somewhere. I have my own notions after messing around, but I could do with a proper 'splanation. Otherwise, perhaps someone can point me to a good article, or propose a good string of search words, and I will do my homework from there. Thanks you. James
 
There are no hard rules about such things. The only technical reason for adjusting one vs the other would be to set the input gain to a level that yields a good signal to noise ratio. But this reason quickly becomes moot as the noise of the input will rise above the noise of the channel with a relatively low input gain (especially when considering the ambient noise of a microphone). Otherwise, the only other reason for adjusting one vs the other might be to get the levels of all inputs to be similar so that you can adjust the faders in a way that is visually balanced. Meaning when all faders are at 0, the loudness of each channel is similar.
 
You should adjust gain to where the maximum input signal is below clipping. No need to be too detailed about it . Leave a margin.
If you have PFL and/or clip indicator lights the it's easier. Clip lights typically give some reasonable margin.
This gets you best signal to noise ratio.
Then adjust levels to mix bus with the level fader or pot.
As pointed out you may wish to modify this to have faders around 0dB for resolution.
You can look up "Gain Staging" for more detailed explanation.
What mixer do you have ?
 
Most mixers are (should be) designed to operate with the channel level control in some nominal specified position. If it is a slider fader it is usually marked 0. So set the channel level to this position and then adjust the input gain obtain nominal signal level. Nominal signal can often be monitored on a meter. How you do this depends on the mixer but it can be a PFL (pre fade listen) or SOLO button or on some mixers each channel has its own dedicated meter.

Check out page four of your Peavey manual

Cheers

Ian
 
The purpose of the channel input gain is to raise the level of the input signal high enough to deliver a good signal to noise ratio. The channel level control is to set relative levels (mix) between the sundry channels.

The gain of the two is additive but if the input gain is set low while the channel gain is set high, you are also amplifying the channel noise more than you would if the input gain was sat high and channel level set low.

Basic mixers like that should be relatively user friendly so it will work adequately with controls over a range of positions. You can probably start with controls mid way and adjust from there if needed.

JR
 
apparently my Peavey anecdotes bother some people... I'm trying to be the magic. ;)

JR
John, I always like those! When I was (as you often say) a Young Puke, circa 1972-73 I worked in the service department of a music store in Okla. City. We were one of the largest Peavey dealers in the country then.

But I'm adding to the VEER! lol

Bri
 
Now to get back on track to the OP's question. One common mistake with independent preamp gain pot and a "fader": set the fader at a low position and then crank up the preamp gain and the preamp will clip. The mixer's output meters will read OK, yet the signal will be distorted.

Others have made excellent comments here. On this PV6, start with the fader at the "0dB" position (the PV6 manual seems to indicate this is a detented position) and use the preamp trim to get in the ballpark. Then use the fader to tweak the final level in the mix.

The manual also shows the channels have a clipping indicator. So if that begins blinking, back down the preamp gain pot.

When I used to do a LOT of recording (to 16 or 24 track tape machines), it was a bit of a "dance" to get the preamp gains all tweaked in realtime while the band ran through the song the first time or two..... and still end up with a usable monitor (and headphone cue) mix at the same time.

One final memory was having to ALWAYS adjust the mic trims "on the low side" level-wise during the run-through, because once the Red Light went on to print a take, the band invariably played louder/harder....especially the drummer.

Bri
 
OK, due to popular demand (?) I will try to share some inside baseball about the PV6. I don't have any personal anecdotes about that series because it was done after I left Peavey over 20 years ago. For a time last century I was in charge of all mixer engineering so the engineer(s) who designed that series would have reported to me. Peavey has been selling value (good for the money) mixers for most of the company's history. It's hard to explain why the world needs yet another new model of basic mixer but it looks like they have squeezed in a few new features. The guitar (fixed EQ shaping) switch is new, the bluetooth capability wasn't even a considerations a couple decades ago. Built-in dynamics and digital efx were being used but not generally included into entry level mixers.

I have already addressed the OPs question, but will repeat that Peavey works hard to make the SKUs relatively easy to operate, and hard to mess up. In general starting with both controls at 12 o'clock*** will probably get it passing usable signal. Fine tuning from there would be tweaking the input gain up as high as you can while comfortably avoiding saturation/clipping, the channel level sets mix levels between different inputs.

I can share some inside baseball about why the faceplate/front of the mixer has two different heights. For low cost manufacturing the mixer uses a single flat PCB inside. The input jacks were nominally 0.950" high, while all the channel potentiometers were shorter (1/2"?).

JR

**** for some historical drama about the 12 o'clock rule (not a rule).... during a product refresh of one of Peavey's top selling powered mixers (thousands a month), my design engineer improved the even simpler one knob channel level control circuit. That one knob controlled both input gain and channel mix level. My engineer (one of my best) figured out how to improve the channel kill so that when it was turned off, it was really off (signal bleed through with the old topology was an area for improvement). Unfortunately this new topology delivered about 2 dB less gain at nominal 12 o'clock. Almost immediately we started receiving field complaints that this new version had less power than the previous model (despite being the exact same power section) because everybody was comparing with the controls at 12 o'clock. Since the customer is always right :rolleyes: we ended up retooling the custom gain pot to deliver the expected gain at 12 o'clock. That was a painful several months but problem solved.
 
THANK YOU ALL for the practical advice on how use the Gain and Level controls on my mixer.

I apologize for the belated reply, but I took time to read, and re-read the comments along with researching articles on "gain staging," "headroom" found on other web sites. Sometimes I take my own advice (which I used to give to clients) and read, re-read and sleep on the matter for a couple of days, because, eventually, one suddenly awakes at 4 AM in a cold sweat with a clear understanding! (Unfortunately, the older I get, the more I need to sleep on it.) :)

It all becomes sort of obvious, once one gets on to it. "Gain" control adjusts input signal level for each channel, putting each input at nominal line level. "Level" control is a sort of fine adjustment of the relative output level of each channel relative to the others, adjusting for changes in signal strength on each channel, such as when a singer sings a little louder on the final take, compared to the sound check.

References to "Signal-to-Noise," "gain staging" and "headroom" now make sense. Parenthetically, there is a somewhat analogous pair of controls on ham radio transceivers. RF-Gain is analogous to the Gain control on the mixer input, maximizing RF Signal-to-Noise at the receiver's front end. AF-Gain is analogous to the Level control on the mixer, adjusting final audio output into a speaker at the far end of the audio chain. Go figure.

Bottom Line - I am already getting cleaner, more consistent results now. THANK YOU for the practical lesson.

James - K8JHR -


PS - My only Peavey anecdote is ... I own a Peavey Special 130 guitar amplifier and PV6 Mixer. Both have served me well for a long time. Several years ago, I read a Peavey White Paper (by Marty McCann I think) on how to use a graphic equalizer which explained one should apply EQ sparingly, and reduce unwanted frequencies before boosting desired frequencies to maximize headroom, minimize distortion and alteration of the original signal. This has proven good advice over time, especially as my wife and I listen to our collection of 80,000 Old Time Radio programs from the 30s, 40s, and 50s, and maximizing computer speech recognition accuracy at my office, assuring clean, articulate audio input to the recognition engine. As you can see, my use of microphones differs somewhat from how others use microphones as discussed on the forum. :)

/JHR /
 

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