Setting Amplifier Gains

Setting Amplifier Gains

After reading our article on how to setup and use your CRO, you're probably wondering how to apply this to tuning an amplifier system.. read on.

For this you'll need:
A CRO (oscilloscope)
A DMM (digital multimeter)


Set Head Unit (HU) settings to 0 & turn off any Xovers (set sub-out level to 0 too). Hook a CRO to the sub-out RCA & blow a 60 Hz tone. Slowly wind the volume up until the HU starts to clip. If the HU gets to max without clipping, then slowly up the sub-out level until it starts clipping. Now you know the maximum unclipped level on the HU.

With the HU on the "safe" level, hook it up to the amp with the gains on MIN. I also by-pass the hi-pass (if possible) and set the subsonic low (around 30 or 15 Hz). Put the CRO on the outputs of the amp, blow the 60 Hz tone and slowly up the gains until it clips, back it off slightly. So now you know the maximum unclipped settings.

With a meter find your note on the max. unclipped settings. Get the SPL reading, then up the volume (or sub-out level) by one and do it again. Do this until the SPL drops.

So now you know the maximum "safe" level on your note and exactly how much clipping you can dial in for maximum output. I find this method is heaps easier and safer than just cranking gains and HU settings like most people do.

It’s good if you want to death match, as you can run clean tones into the subs and not clip them to death.
Or to minimize heat/conserve battery power over the day. Qualify on safe, slowly up the clipping for eliminators & Semi's, and then go all out for Finals.

It’s the method that’s worked best for me so far. Of course, thanks to battery degradation & heat over the period of the day I still suffer power loss/power compression, but the numbers stay the same. Last 5 events I've attended I've used this method and been consistent in my numbers whilst the competition slowly gets quieter.

We've actually gained dB's just from doing this to the amp! Its free power and free SPL you just need to unlock it.

You don’t even need the subs connected to the amplifier to do this, just connect the CRO & DMM directly to the amplifiers output terminals.