How to set gains on a 4-channel amplifier using an Oscilloscope. 

You can get the Oscilloscope here*: amzn.to/3tulKGD *affiliate link

I'm very new to car audio, sans 35 years ago when I was a teen. I do have to say you make things easy to understand for old guys like me. I appreciate the effort you put into the videos as well as keeping all the fluff out. Well done my friend!

This is the absolute best video I’ve ever seen for setting an amp

doug sends his love aka. soundman. we support you!

Good stuff ... thanks! I'm gonna break out my Tektronix scope today as I'm setting up a 5 channel amp. The level will be set to the RMS handing power of my speakers.

I just subscribed to your channel. You're right on the money with this stuff. I did a Google search for osciliscope fine tuning diy class ab amplifier. I saw how to set your gains and didn't know it wasn't a video of the internal components lol. I got stuck though because of how informative you are. Full of facts and math I love it. Also ima big car audio guy as well as my beloved home equipment. Anyways glad I found this channel. Can't wait until I finally buy a scope and can check certain capacitors to really fine to and build some SERIOUS QUALITY HI FIDELITY SHIT MAN!!! ILL BE ABLE TO.CHECK.STABILITY OF THE TRANSISTORS IM USING. SOOOOO MUCH FUN MAN LOL. I learned so much in the 30 to 45 mins I was straight glued onto your videos for the first time. Most of the formulas and convertions I already knew but I learned so much bout setting up errythang wit a MM. You really taught me some shit quickly my dooooooddd. Thanks man

I have a question. Plus, I love your videos. They not like most. You give real numbers and proper facts, that is fantastic, and what I need, the right information. I am still learning all this car audio stuff. I have a 2ohm 800 watt car subwoofer setup, running a 1500.1 D amplifier. However, my amplifier max voltage is 6 volts and I need 6.7 volts to make 800 watts (goes over a bit). According to my equation. Can I set my LOC2 at 6.7 volts and be fine or have to stay at 6 volts and calculate that extra .7 volts to my 40 volt (makes 800 watts) setting on the amplifiers gain?

How’s it going brother! Been learning so much from you and your vids, thank you for your time and effort! Got a request: I’m someone who has a factory head unit, an Audiocontrol Lc2i, an Audiocontrol bass restorer, and an aftermarket amplifier. I’m sure I’m not the only one with the extra bells and whistles :) Can you please teach us where to start checking for clipping, and where to go after each step until we’re done tuning for clipping? Thanks again brother!!

I’ve got a 21 f150 with the B&O system. I’m adding a aftermarket sub. I bought the O-scope from your video. Do you have a video of finding the clipping point of the amplified head unit? I can find a ton of videos on testing a non amplified head units.

When first probing the output to find head unit clipping level, do you start with amp gains at 0?

quick question, i have a oscope and i setup my jbl a5055 which is rated @500rms at 2ohms on the monoblock side. I used a 40hz test tone at 0db and recorded a clean wave no clipping @ 37volts, doing the math that equates to 684rms could that be possible? i verified it with a multimeter (very good quality) my oscope is FNIRSI DSO-TC3 which again is decent enough?? i have two jbl a5055's bridged on the 4channel side (140watts rms x 2 bridged) , both of the amps recorded an identical 37volts with clean wave 40hz 0db test tone, clipping occured around 37.5 - 38volts

Maybe you have covered this in some updated videos, but youtube suggested me this one so I think I may chime in here with some advice. - The aux port is the worst source for calibration since there's an additional preamp/ADC stage that you may be clipping, thinking you're clipping the output stage of the unit. Also another phone will have a different max volume. - It's unlikely that any other input, bluetooth/usb/CD/Radio will have the same peak levels as a given phone, once in the digital realm inside the unit. - Setting a -5dbfs test tone close to the clipping point guarantees that up to 5dB of usable (and used by artists) headroom will be clipped. Use 0dBFs Here's to me, the proper way to do things, and how we generally do it in studios and live venues as sound engineers, but adapted to car audio environment: - Use your ears to check for distorsion, as it starts bellow the apparent clipping level on a low res oscilloscope. The sine will at some point have a buzzy higher pitched sound, you want to stay bellow that level. To check this, set the gain of the speaker amp preamp very low, this ensures that you're very far from clipping the amp input stage and the speakers, then proceed with the next steps. - Use a pure 0dBfs sine wave file via USB, CD/Bluetooth as it's directly digitally decoded and put the output volume of the unit to max. This ensures 0dBfs on the wave file will be 0dBfs on the DAC of the unit. If the manufacturer didn't brainfart the output stage, the signal should be free of distorsion. If it's distorting, lower the volume of the unit until it doesn't distort anymore and never go above that number in day to day use. - Now you have the absolute maximum undistorted signal coming out of the unit. - To set the gain on the speaker amp preamp, i'd then use the oscilloscope and refine with your ear. Your speakers may make have some distorsion at some frequencies that you may want to avoid by lowering the overall gain. - Now there's absolutely no way in hell that the sound will distort unless the source file is already distorted.

First...thanks for this! I just installed a 4-channel amp in my truck and need to set the gains. Question...when setting up the HU, do you recommend setting the equalizer to a flat signal or to the settings that you would most likely have it at when playing music?

Nice video just got the LM2020, I seen other video with DMM and the head unit should be flat , zero settings on treble bass and Mids, my concern is do I leave those setting there? If I want more treble will that change the clipping point from my head unit ? 26 on my volume is the point of no clipping 27 will clip

What are your settings on oscilloscope? Im using a different brand. How do i show clipping.i have a 4volt output on my HU and my oscilloscope goes from 2.5 to 5V theres no in between for 4.

Thank you 🥰🥰🥰🥰🥰

Question: I have a powered(amp built in) JL sub. This method or the oscilloscope wouldn’t work unless I removed the speaker and measured at the wires inside the box, right? This video will help with adjusting gains on my separate 4 channel amp though!

Question. It looks like you found where the head unit clipped by probing the amp at the speaker outs. Am I crazy to think that it should've been tested on the RCAs? Wouldn't probing the speaker outs be show results for the amp? If that's not the case, then was the gain set all the way down when testing the head unit for clipping?

How do you disconnect the (non-sub) speakers from the headunit to set gain on the headunit in cases where the wiring harness to the HU includes power and speakers?

What about using load resistors to simulate a load on the amp ... that will affect clipping point quite a bit.

Hi I have installed in my car a 4-CH amplifier that drives a pair of 2 way speakers (woofers and tweeters) and an other 2-CH amplifier that drives a woofer. So to tune correctly the gains with the O-Scope I should run the below test tones: 1) 50 HZ, - 5 db test tone for bass on 2CH Amp 2) 1000 HZ, - 5 db test tone for mids on 4CH Amp 3) ???? Hz, - 5db test tone for highs on 4CH Amp What test tone should I run for the tweeters (highs)? I did one try with O-Scope and tuned gains at the maximum allowed values of the 4-CH Amp according to the 1000 Hz test tone as you mentioned but I noticed that I have disortion in higher frequencies (8000 Hz and above). What should I do for the hights? Thanks in advance!

I usually set my gains with a 0dB sine tone as I listen to a lot of non-mainstream trap/EDM. Is there something I can use to figure out what the maximum dB is of songs that I listen to, or can you recommend a dB sine tone I should use for my requirements? I know -5dB is the default but I'm not sure if this might be too much or too little and I'm really looking to maximize my gains. Thanks so much for any help you can give!

I have the Alpine SA55V. A 5 channel amp. Where I can bridge the four channels down to 2 channels while still having channel 5 for the sub. The question is would I still use the 1000h tone for the bridge mode since I’m using them for higher power components?

What’s your opinion on the smdd +1! That’s what used to tune my audio! Sounds great! ✊🏾🤟🏽! Great video 💯

Hello can you please tell me how you checked your phone for clipping? I just ordered the same oscilloscope of your link. I will be connecting to the head unit via Bluetooth with my phone.

Can you clamp the ocilloscope probes inside where your speaker wire connects or should you use the tip of the probes on the top of the terminals?

So just a quick question to find my watts using a amp clip meter and oscilloscope do I times amp *vmax or amp*vrms?

Aren't you supposed to use 0dB when testing for max volume on the HU? Then use -5 or -10 when setting gains on the amps?

Tight like a tiger mode😁😁😁

Sane thing as the mustool? Looks like a few on Amazon that look just like it.

I am using DMM method from years never had problems but today when I changed sub I wanted 40VAC voltage but my DMM is not heading ahead 33VAC don't know my DMM went bad or my head unit isn't sending enough signal even though it has 5V pre outs. But what I noticed is my DMM tiny wires went super hot after trial and error so I guess my DMM isn't accurate anymore! Please guide me on the same

I would test all channels. Set the gain from the channel that is clipping lowest. So for the front or rear use the channel that clips first, left or right. That way when you turn your volume up neither channel clips. If you were to use the higher clipping channel it would be clean but your other channel might be clipping. I hope it makes sense.

I bought a LM2020. I set my equipment to flat and everything zeroed out. I connected the oscilloscope to my subwoofer out and ran a 40 hz test tone. The waveform never clipped at maximum volume and as I adjusted the input knob up to clipping the waveform disappeared outside of the screen. I was unable to get a point to see where the waveform started to clip. Do you have any advice?

I see different methods of setting gains and head unit volume. Most people say to turn off your eq settings, bass boost, loudness, etc on both the head unit and amp before setting gains. Others say you need to set all that first so you can set the gains and your amp/head unit won't clip this way unlike if you set the gains with everything off and then added them afterwards. So which is correct?

Loving your bodies after a long break from car audio. If you use a 1k test tone for muds and highs and say have you crossover set at 80-100h will the lower h distort/clip first?

@DIY Audio Guy what do I set the range and time?

If I am checking the clipping point of a factory head unit with a factory amp, do I check it at the speaker before or after the amp? 2011 f150 raptor with Sony system for example

The power and ground are really close on my amp. Can I use a short length speaker with clips to measure

Good video. Can u answer one thing for me. How is this accurate without a load on the amp? The rail voltage will change with a load applied. Could you do this with resistors or a speaker hooked up to see if it’s the same?? Love the channel.

I have this same one and I can't get my waves to change nor ready my ac voltage

Great video but with all this information im still a little confused with one thing. I set it so my amp wont clip but now confused since one set of speakers rms is 60watts and the other set is 90watts rms coaxial speakers. Is adjust the rms somehwere else? I have kicker cxa360.4. And speakers are jbl gto 939 and 629. Any help is greatly appreciated

Thank you very much, can we adjust the high and low frequency with an oscilloscope too?

ok you set the gains on the Amp, but what about the speakers? Are they not taken into consideration at all? What if the speakers I'm using can handle less than what the oscilloscope showed for the amp?

Does this method work on full bridge amps like the taramps

If I ever change my head unit the only thing I have to adjust is my gains, right? Do you have a video on setting up an impedance converter ?

@diyaudioguy The math makes sense for 4ohms but at 1 ohm its different. My amp will do 44.7v cleanly which would work perfectly to my amps spec of 500 watts at 4ohms! When done with 1 ohms my target voltage would be 34.7 which would equal 1200 watts which is my amps rated power at 1 ohm but if I tune using a oscope my amp clearly puts out 44.7 watts cleanly so tuning with a oscope means im getting too many watts at 1ohm? Just curious why the math seems odd here and almost like I shouldnt use the max clean output when doing 1 ohm thanks for any advice!

I assume you set the volts to DC on the oscilloscope when setting amp gains? Another channel had said to set it to AC volts. Which didn't make sense as the car's electronics run on DC.

Hi was wondering can you tell me if this is correct?I have head unit connected to Amp.With gains on amp turned all the way down,Connect o scope to one of the front speaker connections.Then turn head unit volume up untill the o scope shows clipping.Here is were i am not sure.Once i find the clipping volume on HU and turn it down till its not clipping do i leave the volume at the level and then starting turning up my gains?Or do i turn volume back down on HU and start turning up gains?Thanks

Hello! I have a weird issues of my sound, whatever comes to your mind, I've already checked it. I have Shit bass from subs. I tested all Components of Audio, wires, rca's, subs, amps, Head units itp.. My issues: - Different bass quality (in feeling presure too) - Different Output voltage from head units (Kenwood 7200dab new, Alpine cde 178bt) - Voltage on amps body hecked with: (Multimeter one wire to ground terminal amp, next wire to body amp (screw) i can have voltage on all amps dependent of instaled amp location. Now i have to 2volt on my sub amp, before 13v it always drops while reading voltage. - After changing the port of subwoofer to 25hz, i hear a sound degradation from vocal (music), sometimes moving the windows can improve the bass but very rarely. My score is on car closed, 151 db 37hz from 15,5volt to 12,3v voltage drop. but i dont hear and fell this power :/ I fight with this issue about 5 years in two mazda cars... If bass is ok, bass can lost after next enigne start. I recently sold my equipment Clarion sw 3012 and Crunch mxb 480, about 120 watts rms from this sub, and it played well in Renault Clio 3. And there was no problem with the sound at all... This voltage on amps body can degrade sound quality, mallufuncioning Head units? i added ground to amps body, i have 0,000v but problem of sound is still Can you help me? Mazda 6 2007r

How do you test a i-phone as source for clipping level?

Why did you use a -5db track? I thought were suppose to use the 0db track. I have kicker marine speakers and just ordered that scope tool since I couldn’t get the voltage anywhere near what JL audio said it should be for their amp by using a multimeter. Hopefully this Meath is works!

After watching your videos, I bought a small oscilloscope and set my gains. I found my head unit would not clip even with volume maxed out (50). I set my gains with the head unit all the way up. I set both a 4 channel and mono amp for my subs. It didn’t n take much gain to start clipping, probably about 1/4 turn. Does this mean I am not getting the full power available from the amp?

At what level do I need to set the bass level control, on the head unit, while testing for clipping?

To set the head- unit shouldn’t you use a 0db test track?

Is there any way to set a 4 channel amp gains by ear? If so what tone should I use?

I have installed a 4 channel amp but i am going to have a 2 ohm impedance for my mids. Would i still be able to set the gain without my speakers connected?

I've read two ways of doing this. I know some use 0db or say -5dB test tones. And it was said in different places if you use a -5dB, you use that to check when the head unit distorts. Then you use the -5dB to also set the amp gain level. Then someone said if you do that, then that is like having a -10dB setting on the system. And so they said you should always set your headunit volume via 0dB, and then you can use whatever to set your amp gain levels to, i.e. 0dB, -2.5dB, -5dB, etc. I'm wondering, which way is the correct way? I'm going to guess it makes sense to just set the head unit volume via a 0dB level tone, and then pick whatever for the amp gain level. I plan on doing that using 0dB on my head unit and set it, and then putting a piece of tape on my amp and marking amp gain knob at 0dB, -2.5dB, and -5dB test tone, and then playing with the knob to figure out where I want it via listening to music I'll probably start on 0dB on my amp knob, and listen to something soft like Tom Petty, and if I don't have to max the volume out on the head unit, then I'll probably leave it. But if I do, then I'll turn the amp gain knob to my -2.5dB mark and see how that goes.

What would be the proper way for highs

So which tones 0dB or -5dB is the best for setup? For play loud and clean with nice bass

I tried this method tonight in hopes of being able to Bluetooth the sine wave into the system via RU-vid. My sine wave appears to be made of a wave itself. Any clues? Not sure what’s going on.

Should I set my crossovers settings first or after setting the gains ?

Why is it that when figuring out where the head unit clips you had a sound wave but when you went to set the amp gain that sine wave was gone and in order to get it back you had to turn the gain up. Am I missing something? The oscilloscope was on the same two terminals for both the head unit test and amplifier test, so why did the sine wave go away when beginning to set the amp gain. The head unit was still turned up.

Where is the gain when set the HU volume? You don't mention this in the video. Does it not matter?

Hi, I think i'm misunderstanding a step in this "process" because something isn't making sense to me. You set the headunit so that the peak is just starting to flatten out, but then I don't understand what "volume" you set the headunit to when you start adjusting the gain. Because wouldn't where the gain starts clipping change depending on where you have the volume of the headunit? And, if you start adjusting the gain when the headunit is almost already clipping, wouldn't the headunit start clipping immediately after you start adjusting the gain?

Why do my amp cut off certain speakers when i set gains using -5db & -10db but when i set gains using 0db my amp never cuts off?

I have 600W RMS @ 2 ohm mono amp! However my subwoofer is rated at 400W @ 4 ohms, wouldn’t my amplifier clip over 34.64 volts (√600W*2Ω= 34.64V)? If so, with the subwoofer above my amplifier will output at 4 ohms √400W*4Ω= 40v. That seems a bit high. I was thinking because my mono amplifier is a 2 ohm stable class d amplifier, shouldn’t the formula technically be √400W*2Ω= 28.28V and that shouldn’t be clipping cause 35V+ should clip cause that’s max voltage output out of the amps channels? Or am I just overthinking 😅

Is this process different with a 5 channel

Can anybody help me build a Balanced line driver for some Old School Soundstream amps and crossover? I have amp schematics and Pin out for the line driver, but all of the schematics I see are from home audio. I'm stuck and don't know where to look. If I'm in the wrong place and being rude, all apologies.

How do you check the phones clipping level? Mine doesn’t have a headphone jack

Can you do a video on how to calculate a port, tune etc using pen and paper or along with a free sub box calculator? Anything but winisd. Winisd is confusing.🤦🏿‍♂️🤦🏿‍♂️🤦🏿‍♂️ Preferably pen, paper and a calculator. I love all your videos. I’m learning.👌🏿👌🏿👌🏿🔥🔥🔥

What if my amp is rated for 2000 watts rms at 1 ohm, which would be 44.7 volts but it doesn’t start clipping until 50 volts which should be 2500 watts rms, should I set it to the 50 volts right before clipping or the 44.7 volts for the 2000 watts rms rating?

1000hz test tone to test deck output?

So - what volume is the head unit set at when doing all this testing? 75%?

This Does work until you get a big amplifier the waves are too big and the current is too powerful for you to be able to see the sine wave on a toy oscilloscope. I was setting my JP 234 which the oscilloscope did give me a little bit of an idea of how clean the signal is coming out of the jp. It's a little dirty. Okay so I can't see the top of the sine wave you can motivate one side all the way down so you can see just the top or just the bottom from the middle and it's so much power I can't see it

You may be the first who can *actually* do a how-to for WinISD and have it understandable. I have watched so many videos on WinISD and it is still confusing. When the T/S parameters are entered does WinISD spit out "a" box specific to the numbers or is WinISD used to manipulate the T/S numbers to get several different custom boxes???? No need to answer - it is just one of the MANY WinISD questions

How about setting the gains on your videos? Some of them are too quiet and some of them are too loud.

you assumed a 4 ohm load to calculate power in watts. How do know the meter is a 4 ohm load?

*0:40** Wouldn't a calibrated pink noise be better?*

It doesn’t matter that the amp isn’t under a load?

One thing, your background music is too loud and distracting. But your info is solid.

Let’s do a hypothetical. Say you are setting up a gain knob on 4 channel amp and the only tool you happen to have is a multimeter. You would obviously use a 1000 Hz test tone at around -5 dB. But just out of curiosity you play a 50 Hz test tone at -5 dB. Would you get the same voltage reading? From what I understand and have experienced you shouldn’t right? Which leads to my next question. The operating range for a multimeter is around 50-60 Hz because our power outlets in the US are around 50-60 Hz. Wouldn’t that make a 1000 Hz test tone inaccurate? Please correct me if I’m wrong I want to learn things.

How about a deal?.....get a bass van and I will subscribe!

I can't get a clean signal at all on my JP 84, shit is squiggly. Alpine cda147bt is good at 26/35

Good night need some help please

Don't you mean "17.3V" instead of "7.3V" @3:10.

According to RU-vidr DAmoreEngineering the correct formula for calculating the "Real Power" of an AC circuit with a reactive (non-resistive) load is: V(rms) x I(rms) x cos(Φ) (where Φ is the "phase angle" or the phase difference between the voltage and the current) See his video here: ru-vid.com/video/%D0%B2%D0%B8%D0%B4%D0%B5%D0%BE-qwxlnSDv9wY.html Any thoughts?

you don't need a resistor to load the amp

MAN YOU DID NOT SHOW THEM HOW TO PROPERLY SET UP GAINS WITH AN OSCOPE. YOU SHOULD HAVE SET THE GAIN WITH A LOAD ON IT! THAT IS THE CORRECT WAY!

I can’t focus on what he’s saying with such loud music . I am leaving

Hi I have 4 midrange speakers on a 500.4 Amp. Where in the Amp can I adjust to make my speakers alittle louder . On my headunit when I turn volume up to 25 it is not loud enough