Amp Gain using O scope

[7saiin]

Im having trouble knowing the way to set the amp gain using O-scope for different ohms, lets say the amp can handle 1/2/4 ohms, so when the sub is not attached how do you set the gain with o scope for different ohms? each ohm means different voltage, so how to set the gain for 1ohm in my case?

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[Doxquzme Premium Member]

You don't set gains for the different ohm rating of the woofers you are going to use. The woofer wiring configuration for the amp and the sub determines the resistive load (impedance) it will operate at. What is the low-level output of the HU, what amp, what sub(s) and how is all wired together needs to be established. Once that has been vetted, wired correctly, etc. then gains can be set. Gains are set in accordance with the low level output of the HU to try an match as closely as possible, the input of the amplifier capabilities/limits. They are not a means to increase or decrease volume (and they should not be used this way) so that you don't overdrive the amplifier into clipping. Need the equipment particulars noter earlier for anyone to assist further.

 

[1aespinoza 10+ year member]

You don't set gains for the different ohm rating of the woofers you are going to use.

Actually you do. The only time I see a need to set the gain using the radio's maximum output voltage is when you will be using a DSP, X-over, or Graphic EQ. You see what the radio can put out at 75% (100% for quality radios) volume, then set input gain on the device. After that, you keep radio volume at the 75% and set the amplifier gain using the speaker's resistance and the power you want to send to it.
So if you have a 1kW amp with a 500w RMS sub, you will set output for 500w RMS.
I do not know how to use an oscilloscope for setting gain. I only know you can see noise or clipping when the hardware is pushed too far.

 

[Doxquzme Premium Member]

Actually you do. The only time I see a need to set the gain using the radio's maximum output voltage is when you will be using a DSP, X-over, or Graphic EQ. You see what the radio can put out at 75% (100% for quality radios) volume, then set input gain on the device. After that, you keep radio volume at the 75% and set the amplifier gain using the speaker's resistance and the power you want to send to it.
So if you have a 1kW amp with a 500w RMS sub, you will set output for 500w RMS.
I do not know how to use an oscilloscope for setting gain. I only know you can see noise or clipping when the hardware is pushed too far.

Granted, maybe an oversimplification on my part, what I was trying to impart is that once the wiring of the sub and the connections/settings for that amplifier (minus the gains) is established, then you go to work on the gain settings.

 

[1aespinoza 10+ year member]

Granted, maybe an oversimplification on my part, what I was trying to impart is that once the wiring of the sub and the connections/settings for that amplifier (minus the gains) is established, then you go to work on the gain settings.

Gotcha. I actually set my amp gains by ear. I like to use only the first ten "clicks" of the radio volume. I find that gives the cleanest signal from the radio because after that you can start hearing the hiss gradually when nothing is playing.
The downside would be if someone would raise the volume past ten, it could damage the speakers.

 

[spokey9]

The downside would be if someone would raise the volume past ten, it could damage the speakers.

Nobody touches my knob without a deposit

 

[huberoy123 10+ year member]

Im having trouble knowing the way to set the amp gain using O-scope for different ohms, lets say the amp can handle 1/2/4 ohms, so when the sub is not attached how do you set the gain with o scope for different ohms? each ohm means different voltage, so how to set the gain for 1ohm in my case?

I look at the specifications for the HU output and matching it with the amplifier input. This has always worked for me. I purchase speakers that my amplifier is rated for and let "mother nature" figure out the rest.

 

[1aespinoza 10+ year member]

Nobody touches my knob without a deposit

TMI.

 

[Firewalker]

Nobody touches my knob without a deposit

Man the reasons why you use sancho more and more are coming to light!

 

[spokey9]

Man the reasons why you use sancho more and more are coming to light!

I hold firm on the deposit in all situations