How to Set Your Gains Using Ohms Law and a Basic Multimeter

Setting your gains properly with a multimeter is easier than you might think. The gain adjustment control on an amplifier is commonly misunderstood as a volume knob. However, it is supposed to be used to level match the output voltage of the head unit to the gain of the amplifier so the input signal isn't "clipping" causing distortion and potentially damaging your speakers.

[jmccoy]

I've watched multiple videos and read multiple articles on this and this video by far was the easiest to understand and I've played around with my settings bass boost all that even using an ocillascope....but tuning my amp exactly the way y'all have directed in this video just using a dmm made my system sound 10 times better.

[MTXAudioUSA]

@Alex Villanueva - However you plan to wire the subwoofer(s) to the amplifier. If you are wiring two subs down to a final impedance of 2ohms, you would use two ohms for "R". If you are wiring one DVC sub down to 1ohm, you would use one ohm for "R".

[HariKrishnan-jlhm]

Thanks for the video
I have 2 Doubts
1., can you explain what should be the positions of HPF & LPF, switches while doing the gain setting for speakers and subwoofers
In a 4 channel amp.

2. In every videos in YouTube regarding the gain setting, they are using RCA input.. is that mandatory.. ?? What would happen if I use speaker level input instead of RCA while doing the Gain setting...

[DubPeezy]

I went to an audio shop to install a five channel and they were good “installers” but were not technical.had no clue how to properly set the gains on the amp and lc7i. had the levels up way too high. Took my multimeter and set properly using the technique in this video since I don’t have a SMD 2. Thanks.

[madisyn]

My amp has both a gain control and master level. When doing this where should the master be set? If it's all the way down there's no output at all no matter where the gain is set. Should it be all the way up and set the gain based around that level? Or find some balance between the two? The amp is a Jensen xda91rb. Also worth mentioning that there's no controls on the amp. Everything's controlled through an app via Bluetooth

[marcusaurelius]

If the subwoofer 4 ohm but it is bridged, ohm is cut in half. İn this case we calculate by multiplying RMS by 2 instead of 4 ohm, correct?

[delusansanthiapillai]

Excellent video I just have one question when your playing the 50hrtz do you keep your bass and treble settings on the head unit or do you zero everything out

[yourehating]

to start my amplifier claims to be rated 1400rms at 1 ohm. massive n3 nano block amp. I wired my dual 2 ohm subwoofer down to 1 ohm load a rockford t2 12 1200rms.. how do I match my amp to this sub. my desired rms is 1200.. if 1200 x 1 ohm is still 1200. and the square root of 1200 is 34.64 .. is that correct or did I just go wrong I'm lost plz help

[BkHitmarker]

Why do you use a CD with 50hz? i'm trying to do this with all my components in the car already, and my head unit is connected to my amp and my regular car speakers. Any suggestions? I'm thinking i will disconnect the car speakers from the head unit so i can turn the volume all the way up with out waking my neighbors.

[Flightguy]

I have tried all methods of tuning but nothing works to me as well as tuning by music, but I do not like that method because it's not precise. I currently have a 12" Alpine Type S on 2 Ohms in a ported box that's tuned to 32Hz being powered by a JL Audio Slash 500/1. I'm wondering, would it be better if I played a 32Hz test tone, tuned it by ear and then record the maximum UNCLIPPED voltage and then play various music and increase the gain until I reach that voltage I achieved at 32Hz? I'm wondering becuase the 50Hz method does not work well for me at all, when I tune it using this method and clamp my amplifier the maximum I see is 250-300 Watts RMS @40Hz when I should be seeing 500 Watts RMS. It also doesn't feel like 500 Watts using the Ohms Law method.

[murkinmurdock]

So my sub is wired to 1 ohm

So I would do 1000 x 1= 1000
Then square that= 31.6 correct?

[therealkcmill]

Bass boost off, radio at 3/4, bass knob at 3/4 play test tone close to box tuning or cabin resonance, then multimeter the speaker output of your amp measuring VAC turn the gain up until your at your calculated voltage [VAC=√power (desired wattage)x Resistance (your ohm at the amp)] VAC=√P*R

[_takeitz]

Is that a tnp212d2 or tnp212dv? I have the dv paired with mtx tna500d. Are they the same?

[samlafiura]

how do you determine your target voltage?

[jorgecano]

I have an amplifier 1800 watts and two 12 speakers 4 ohms each should i calculate by time 4 or times 8?

[travisaeschliman]

Thanks for the video.  I'm still hung up on the R term, it seems like I've read conflicting info on the web.  I have a single 10" 4-ohm DVC subwoofer that is rated for 300W RMS.  I have a mono amplifier that outputs 300W @ 4 ohms or 500W @ 2 ohms.  When I calculate V = (P*R)^0.5, I am using R = 2, since while my subwoofer is a 4 ohm model, because of the wiring and single subwoofer it puts a 2 ohm load on the amplifier.  If I set P = 300W, I then get a target V = 24.5 volts.  Does this seem correct?  Because some other info I have come across seem to indicate that in my setup R = 4, in which case my target V = 34.6 volts!  Thanks!

[MTXAudioUSA]

@Lucas Patterson - If you have two single 4 ohm voice coils, you can wire them to a total 2ohm load or an 8 ohm load. To see how to wire to these impedances, go to If your amplifier is 90 watts for one channel, be sure to use the wattage ratings at whatever impedance you are wiring your subwoofers to. 90 watts isn't much for two subwoofers so you will most likely under power your subwoofers which can be worse than overpowering them in some applications.

[Lordvoldemore]

My led clip light will turn on when I adjust the filter afterwards so I set the filters first then adjusted the gains.

[hector]

So if I have 2 subwoofer at 2ohm each do I multiply by 1 ohm total??

[devinkrier]

Will doing this hurt my door speakers? I can’t really unhook those