Mixer / Power amp / Decibel Meter setup


I just bought:

Before buying the decibel meter, the setup was clear to me:

Mixer --> Power Amplifier --> Speakers

Then I bought the decibel meter, and I'm confused on how to connect all this stuff together. Should I split the output line of the mixer, so that the same output goes to both the amplifier and the decibel meter, like:

Mixer |--> Power Amplifier --> Speakers
      |--> Decibel Meter

Or should I connect the decibel meter before the amplifier (because the decibel meter has two L/R outputs), like:

Mixer --> Decibel Meter --> Power Amplifier --> Speakers

But what about the sound quality (because the sound goes to the decibel meter first)?

Or should I connect the decibel meter after the amplifier, like:

Mixer --> Power Amplifier --> Decibel Meter --> Speakers

But I'm worried that the decibel meter can fry.

Any help would be appreciated.



Posted 2013-01-17T05:10:17.670

Reputation: 143



According to the Amazon link you provided for the Decibel Meter, the inputs are line level. This means that you will need to hook up the meter directly to the Mixer as in your first and second diagrams. If you hook up the meter between the amp and the speakers bad things are likely to happen.

Since the mixer only has unbalanced output, hooking the decibel meter up between the mixer and the amp will probably be the way you want to go.

Mixer --> Decibel Meter --> Power Amplifier --> Speakers

You will want to hook up the equipment, then turn the volume up as high as you are likely to go and adjust the Decibel meter accordingly.

Friend Of George

Posted 2013-01-17T05:10:17.670

Reputation: 3 426

Thanks. Two questions: Don't I lose quality by making the signal go to the decibel meter first and then to the amp? Shouldn't the decibel meter measure the amplified signal outputted by the amp, which is the signal that then effectively powers the speakers? – None – 2013-01-20T02:04:35.310


  • You will add a tiny bit more noise by connecting it like this, but if the meter is not directly in line between the mixer and the amp you will not get a true picture of what is being sent to the amp.
  • < – Friend Of George – 2013-01-21T14:46:32.247


  • Unless the amp is changing the sound significantly (with compression, etc.), the levels will look the same on a meter before or after the amp. Since this meter is line level, you have no choice but to put it before the amp.
  • < – Friend Of George – 2013-01-21T14:47:00.763

    Thanks. One last question: What does it mean when you say to "adjust" the decibel meter? Shouldn't the decibel meter automatically detect the outputted power and show it? – None – 2013-01-23T11:15:58.923

    According to the description it has a sensitivity adjustment. This means that you can adjust the meter so that it peaks at the proper levels. For your situation, you will set the volume the highest you can go without distortion and change the level of the meter to peak near the top end of the red section. Then when you look at the meter you will be able to see how close you are to distortion. – Friend Of George – 2013-01-23T14:21:43.647


    I haven't got any experience with decibel readers. However, after doing some research on the internet I found this:


    It almost walks you through the connections. I think you need to try what it suggests just to move forward from where you are if you can.


    Posted 2013-01-17T05:10:17.670

    Reputation: 351

    The linked page does not give clear directions as to how to set up the decibel meter. – Friend Of George – 2013-01-17T14:23:31.940


    The accepted answer is incorrect. The Yamaha mixer output is a balanced 1/4 inch TRS output, the amp has balanced inputs on TRS or XLR. So the right way to connect the mixer to the amp would be using a balanced TRS to Male XLR cable.

    Unfortunately, the dB meter has only unbalanced in/out, which if placed in the middle will result in making the balanced connection into an inferior unbalanced connection. This may cause a noise problem down the road, it may not.

    Most balanced to unbalanced adapters and cables short one side of the balanced signal to ground, breaking the balance.. and this will happen whether you split the output of the mixer, connect the dB meter in the middle, or place it after the amp. The result will be the same.. unbalanced.

    The way I would do this would be to get TRS to Male XLR cables, like this:


    Which would go between the mixer and the amp.

    And then TRS to dual RCA cables, like this:


    ..two of them, one for each channel, which you would connect between the amp and the dB meter, where the two grey RCA's would connect to the dB meter input, and the red connections would not be used (put some tape over them).

    It's not perfect but it's FAR better than losing your balanced connection.


    Posted 2013-01-17T05:10:17.670

    Reputation: 411