Getting A Clean Signal Path

The Music Telegraph | Text 2020/08/17 [13:03]

Getting A Clean Signal Path

The Music Telegraph| 입력 : 2020/08/17 [13:03]

 

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Getting A Clean Signal Path

 

A typical signal will go through many different amplifiers on its way to a meter and your ears. If you hear objectionable distortion that you need to fix, you will have to start thinking about all the circuits in the signal path where the audio could have become distorted. Most of the devices in the signal path will not have metering connected to them so you will have to establish an approach to setting the gain that will insure the device in question could not be distorting, then  move on to the next device and so on. You finally end at the meters and headphones, and hope hopefully the distortion will be gone. The trick here is to make sure that each individual device is not adding distortion. 

 

 

Let's assume that you are playing a signal that is not distorted. You will be directed to set up the signal chain so that it will be very distorted by the time it gets to your headphones. Then you will track down where the distortion is coming from and finally set the gain structure correctly so that the signal is not distorted. You may use an oscilloscope and a peak meter to help you along the path to righteous signal.

 

 

A mixer is a collection of electronic boxes that are put together to control quantity (amplifiers) and quality (equalizers). There is the input preamp, then the eqaulizer (itself a collection of three amplifiers), the channel level amp, then the combining amp for the left stereo buss, then the left master buss amp (that's the one connected to the master fader) and finally the monitor amp. If you were counting, that's eight amplifiers. And anyone or more of them could be overloaded. If a signal is distorted because its level is too high for the amplifier to handle, then it makes sense to lower that signal level until the distortion goes away.

 

 

 

The 3-Step Plan to a Cleaner Signal Path

 

1. Set up the master mix buss to unity gain.

 

2. Set up the channel gain to unity gain.

 

3. Slowly increase the input gain until distortion is just seen or heard then back off till it disappears.

 

(Note: Some input stages have an overload led indicator that is very helfpul in doing this step. Just adjust the level until the led just starts to light, then back off the control until it just stops lighting.)

 

 

 

 

 

 

 

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