Another amp gain setting topic...

[djtomczak 5]

I have an old school Memphis amp putting 1500 at two ohms into two SA12s. Bass boost on the amp is 40hz, I have the bass boost up a quarter. Amp gain is at half right now but, BUT. I have a feeling it's not all the way up. I usually set my gains by playing Put On by Jeezy since it has a few different levels of bass and I can set it so it doesnt clip on any of those. I don't feel like im doing this right, so I need pointed in the right direction. I get a 40hz tone and put the bass boost to what? I just need help...

[slim2fattycake 85]

bass boost off. half gain doesn't mean half volume.

[djtomczak 5]

I know but I don't know what frequency to set the gain to, I have knowledge of what gain does and electronics:p

Edited December 9, 2011 by djtomczak

[audio-neon 34]

Take a tone, say 50 hz and turn your gain up slowly, as soon as you hear the sound change (distort) back the gain down slightly....

Your volume on your headunit should be at ~3/4 (that's about where the rca outputs start to clip)

[Loud n Clean 1]

I have an old school Memphis amp putting 1500 at two ohms into two SA12s. Bass boost on the amp is 40hz, I have the bass boost up a quarter. Amp gain is at half right now but, BUT. I have a feeling it's not all the way up. I usually set my gains by playing Put On by Jeezy since it has a few different levels of bass and I can set it so it doesnt clip on any of those. I don't feel like im doing this right, so I need pointed in the right direction. I get a 40hz tone and put the bass boost to what? I just need help...

You should get a DD-1! It will allow you to adjust your gain to match your source unit perfectly. But if you don't have $150 to invest in one of those you should at least use a dmm to set it, it's not as accurate as using the DD-1 or an Oscilliscope but it'll get you alot closer than trying to do it by ear.

This is a very easy method for properly setting the gain. While gains can be set by ear, the proper level would be subjective to the listener. The DMM method is favored because it is quantifiable and not subject to personal bias. It works by measuring the output voltage, or rms power, that your amp is producing while connected to your unique wiring/head unit configuation. This handy chart is for reference:

Step 1: Determine the RMS output of one channel of your amplifier and the rated RMS input of your speakers/subwoofers you will be using on that channel. Select the lower of the two for referencing the chart above.

Step 2: Match the impedance (ohms) you have on one channel of your amplifier to the column on the chart.

Step 3: Turn your amplifier gain all the way down.

Step 4: Disconnect all speakers/subwoofers from the amplifier

Step 5: Insert the leads of the multimeter in to the channel you are setting (if bridging an amplifier use the terminals you would be using)

Step 6: Set the multimeter to ac volts

Step 7: Turn on the head unit, zero out all EQ settings, turn off all filters (low pass/high pass), and make sure loudness is off.

Step 8: Insert the test tone cd

Step 9: Set the volume to 75%-80% of the maximum volume on your head unit.

Step 10: Start playing the appropriate test tone - recommended 50hz for subwoofers, 1000hz for mids/highs

Step 11: Slowly turn the gain until you obtain the voltage from the chart

Step 12: Turn off the head unit, unhook the multimeter, hook up your speakers/subwoofers, then readjust your filters/eq settings to your liking and you're done.

[Beandip 3]

^ sorry, but I wouldn't even waste my time with that DD-1 (an o-scope would be a much better investment anyways). Sure it may set the gain right but the source volume is constantly changing with different CDs/mp3. So as soon as you pop in a different cd your efforts were wasted.

Tune by ear, leave the DMM and the o-scope for something else.

Edited December 9, 2011 by beandip

[Loud n Clean 1]

^ sorry, but I wouldn't even waste my time with that DD-1 (an o-scope would be a much better investment anyways). Sure it may set the gain right but the source volume is constantly changing with different CDs/mp3. So as soon as you pop in a different cd your efforts were wasted.

But that never changes no matter if you tune by ear or with the device of your choice, so why guess?

[audio-neon 34]

The method you listed with a chart has as many flaws as tuning by ear.

Clipping with a tone is a pretty distinct change in "pitch" probably the wrong wording. I have used ~4000 watts of amp on 2 800 watt subs without an issue tuning by ear.

[audio-neon 34]

Also tuning by ear is far from guessing. There is a reason why pro's do it by ear.