Setting Gains

[kipperj]

Hey, DJF. I'm sure there may be a thread somewhere about this, but I can't seem to find it.

Anyway, I was wondering how to PROPERLY set gains and volumes throughout my setup. I'm not sure there's much else I can say about it...
My setup goes as follows:

MacBook Pro --> Peavey PV10 Mixer --> DOD Crossover --> Amps

Amps are: 1 Peavey IPR 3000 for tops, 2 PV900s for bottoms

Another question I have is how to know when to "back off" when I have an amp that's rated higher than the RMS rating on speakers. Should I just listen for distortion?

Thanks for reading. Forgive me if I left anything out :/

[windspeed36]

I run my setup:
Amps/Speakers full power for passive or 0dB for active
Processing: 0dB out
Mixer: 0dB out
Channels and faders are set according to the input's volume

Here's something that will help you.
http://youtube.com/watch?v=1hwT15SSwgU

[DJ Boom Bap]

Google "Unity Gain"

[sss18734]

A lot of people max out their amplifier's gain and then adjust their mixers. That's easy, but isn't really the best way to do this, especially if you are using the speakers at low volume or for announcements. If you have some time, you should do the opposite.

Keep the amplifier gains as low as possible to minimize noise and feedback.

What kind of speakers are using? You'd be surprised how much power a lot of speakers can take given they are receiving a clean signal.

[kipperj]

I run my setup:
Amps/Speakers full power for passive or 0dB for active
Processing: 0dB out
Mixer: 0dB out
Channels and faders are set according to the input's volume


Sorry for the noobish question, but how exactly do you know when your amp is at full power if it's not connected to a meter?
And I won't want my sub amps to be at full power, since it's rated output is higher than the RMS rating of my subs. What do I do about this?

[kipperj]

A lot of people max out their amplifier's gain and then adjust their mixers. That's easy, but isn't really the best way to do this, especially if you are using the speakers at low volume or for announcements. If you have some time, you should do the opposite.

Keep the amplifier gains as low as possible to minimize noise and feedback.

What kind of speakers are using? You'd be surprised how much power a lot of speakers can take given they are receiving a clean signal.

As of now, I'm running 2 PV115s and 2 PV118s. Low end Peavey, but I'm looking to upgrade in the near future.

[sss18734]

As of now, I'm running 2 PV115s and 2 PV118s. Low end Peavey, but I'm looking to upgrade in the near future.

You'll be fine running your amps just under clipping. General rule of thumb is to give speakers at least 2x their RMS rating anyway.

[windspeed36]

Keep the amplifier gains as low as possible to minimize noise and feedback.

Amplifier levels don't have much to do with it. They are just as much of a culprit as the rest of the system.


Imagine, for example, that you place the microphone in front of the speaker. Now you tap on the microphone. The sound of the tap goes through the amplifier, comes out the speaker, re-enters the microphone, etc. This loop happens so quickly that it creates its own frequency, which we hear as a howling sound. The distance between the mike and the speakers has a lot to do with the frequency of the howling, because that distance controls how quickly the sound can loop through the system.


Sorry for the noobish question, but how exactly do you know when your amp is at full power if it's not connected to a meter?
And I won't want my sub amps to be at full power, since it's rated output is higher than the RMS rating of my subs. What do I do about this?

If I were you, i'd follow this layout.

Amplifers: max/no reduction (all the way to the right)

Crossover: have the HF and LF set at 0dB and use the crossover to adjust the ammount of HF to LF depending on your environment. After a few gigs you should be able to have it set and leave it for good.

PV10 Mixer output: have the LR master set at 0dB.

PV10 Mixer input: What are you running through the individual channels aside from your mac? I'd have the mac's channels (LR) set at 0dB and the gain just back from clipping (see below how to config)

Configuring channel gain:
1. Have the fader all the way to the bottom of the slider

2. Input the loudest signal that you are likely to have that night into the input (mic, instrument ect).

3. Turn the gain up untill the clip light begins to show then back it off a bit.

4. Bring up your channel fadder until the desired accoustic balance with other channels is reached. (i.e for a band, the guitar isn't destroying everything else)

Hope this helped

[ampnation]

You will find there is no one answer here. Your best bet is to learn as much as you can about how gain and attenuation work on a more technical level. I think one thing you should be doing is using a limiter. This will be more important for live sound than for recorded music, but still should be done.

Besides that the one thing I see that I would fix IMMEDIATELY if I were you, is to add an audio interface. Even a cheap one like a Numark DJIO will do the trick. I think you would find a big improvement in sound quality over connecting the 1/8" stereo jack directly to your mixer. I know I did. For the record, my equipment was, Lenovo ThinkPad T400 to Ecler Nuo 3 when I added an M-Audio MobilePre (connects to the laptop via USB) I could tell the difference without A/B testing.

[sss18734]

Amplifier levels don't have much to do with it. They are just as much of a culprit as the rest of the system.

Amplifier gains induce much more noise than a low-level mixer gain. The difference is extremely obvious without any music playing.

You're right in that there isn't a single, totally correct way to do it. Especially if you're playing music at high levels all night, there isn't really a problem with keeping your amp gains maxed (as long as you are using your mixer correctly).

But if you're inexperienced or you are doing an event where low output is common (think weddings or corporate events), maxing our your amp gains is noisy and risky. Especially if you're a novice, you'll eliminate the possibility of slamming your mixer volume controls too high and potentially damaging your equipment.

[kipperj]

So, do I start with the amps and make my way up? Or start at the mixer and go down? I've always set my sliders (both my master and channels) to 0db and added gain until I saw the yellow lights flash occasionally next to the output. If this is the case, are these sources telling me to keep my gains on my crossover at 0db? The wording with some of the sites I've seen have been a little difficult for me to grasp. Also, what would I do about my computer volume?

[ampnation]

If your amp is well matched to your speakers, start at the source and work your way to the amp and most likely leave your amp at full gain (actually the "gains" are attenuators which throttle the amp, but that's another subject.)

If your amp is overpowered for your speakers, do the same thing then decide whether to throttle back your amp or the output that directly feeds it.

For best results, use a multimeter to measure output using a test signal. That google search on setting gain structure should have turned up some talk about how to measure the voltage and know what number you're looking for.

[Al Poulin]

Sorry for the noobish question, but how exactly do you know when your amp is at full power if it's not connected to a meter?
And I won't want my sub amps to be at full power, since it's rated output is higher than the RMS rating of my subs. What do I do about this?

When your limit/clip lights are flashing the amp is at or near its maximum output capability. This can happen regardless of where your attenuators (gains) are set if you feed the amp enough signal from your mixer. When you see the clip lights light up, reduce your levels quite simply. Also, make sure your channel clip indicators (on your mixer channels) are not blinking. you do not want to send an already clipped signal to be amplified and put through your speakers...


Al