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How many people use a DMM to set gains?
I've always set the gains on my sub amps by ear by just turning the HU volume to 3/4 of max and turning the amp gain until I hear distortion in the music playing and then backing off until the distortion is gone,
well on my newest system I decided to set the gains using a DMM as I figure it must be more accurate than just "earing" it.
Well I used the formula for my amp MRP-M500 which is 500 watts at 2ohm and it comes out to 31.6 Volts output.
So I set HU to 3/4 volume and turn all eq off and levels zeroed in HU, turn the gain up on the amp until I get 31 volts on the output.
I did the same for my 4 channel which comes out to 14.1V at 4ohm per channel.

Now problem is my sub amp is only at maybe 1/3 of the gain. And is very low in volume compared to my front speakers (not using rear atm), when I say low I mean you can't even barely tell the sub is playing.

I can crank the gain on the sub amp to about 3/4 and get a good balance with the front speakers but the output voltage on the amp goes up to like 46Volts.
I don't get any distortion in the sub and it plays clean and sounds good all the way to a little under the max volume on the HU with it set like this.

Just wondering if I am doing something wrong or maybe the Alpine wattage is underrated?

Again sorry for the long post and thanks for the help everyone.
 

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DMM method is really only good for limiting output of an amplifier IMHO, not setting for maximum clean output.

To use the DMM method effectively, you'll want to find the HU's maximum clean volume level (as one would want to do whenever setting gains) and then use an attenuated test tone of say -5dB to upwards of -10dB for sub amps.

honestly, setting gains by ear with the aid of test tones is more accurate and fairly easy, as most can hear 1%THD (when the hum of the tone turns to a buzz at the onset of 2nd and 3rd harmonics).

And I'm going to ASSuME you used a 0dB test tone, which music is NOT recorded at. Very seldom will you get anything recorded in the track at 0dB, major bass peaks. On average, the audio will be attenuated around 10dB or so.
 

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Why not set gains to match efficiency of drivers AND most importantly to lower noise.

If it were me , I love my gains all the way down. And up a tad on the least efficient driver set.
 

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Discussion Starter #5

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The dmm method is a waste of time, set them by ear and be done with it.


As was mentioned earlier, most cheap meters lose accuracy the further you get from 60hz.
 

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Yep, as you can see, the model you have is off at higher frequencies and reads lower than the actual voltage. So, you have the 4-channel set as though you used an attenuated tone and the sub amp set with a 0dB tone, which I covered that recordings rarely have.

Reset your gains by ear with the aid of test tones, then lower gains as needed to blend the system together.
 

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How many people use a DMM to set gains?
I've always set the gains on my sub amps by ear by just turning the HU volume to 3/4 of max and turning the amp gain until I hear distortion in the music playing and then backing off until the distortion is gone,
well on my newest system I decided to set the gains using a DMM as I figure it must be more accurate than just "earing" it.
Well I used the formula for my amp MRP-M500 which is 500 watts at 2ohm and it comes out to 31.6 Volts output.
So I set HU to 3/4 volume and turn all eq off and levels zeroed in HU, turn the gain up on the amp until I get 31 volts on the output.
I did the same for my 4 channel which comes out to 14.1V at 4ohm per channel.

Now problem is my sub amp is only at maybe 1/3 of the gain. And is very low in volume compared to my front speakers (not using rear atm), when I say low I mean you can't even barely tell the sub is playing.

I can crank the gain on the sub amp to about 3/4 and get a good balance with the front speakers but the output voltage on the amp goes up to like 46Volts.
I don't get any distortion in the sub and it plays clean and sounds good all the way to a little under the max volume on the HU with it set like this.

Just wondering if I am doing something wrong or maybe the Alpine wattage is underrated?

Again sorry for the long post and thanks for the help everyone.
I am going through the same thing right now. I’m so glad I found this
 

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There are numerous ways to find your HU's maximum clean volume level and set your gain.

By ear/sight using test tones.


Using a speaker with a capacitor.


Using a piezo buzzer.


Making your own DIY distortion detector that Rockford posted a pdf file on how to make YEARS ago.



Cheap O-Scope you can buy for like $40-$80.



Keep in mind that unless you use an attenuated test tone, you're leaving a lot of power off the table. I'd recommend -3dB or -5dB.
 

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So based off this information sub amp should be set with an attenuated tone say -5db and mids and tweeters at 0db?
 

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Tweeters definitely 0dB, then backed off to blend with mids.

Mids could be set with -3dB or maybe -5dB, as you'll want to not leave a whole lot of power off the table.

Subs -5dB to upwards of -10dB, as you can't hear distortion vas easily in lows. This will also allow for much more dynamic output from the sub stage.

However, you can take some of the music you listen to and run it through audacity to see what the average recording level is and what the recording level of peak bass hits are, if you're looking to squeeze our all the power you can.

Remember though that for roughly 3dB in increased output, you're asking for double the power. So it's not like a you'll really notice the difference in feeding your subs say 70% of their rated power vs 100%.
 

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For me personally I would never ever set them by ear , I would never be sure it's correct doing it by ear , I always do it with an oscilloscope as you can clearly see what is going on and allow yourself some headroom if wanted , I could never do that by ear.

Or a clipping indicator would do the same job but the oscilloscope is the best way for sure and what I always use.

I set my levels with -5db test tones for mid/upper frequencies and -10db for the Subwoofer.
 

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There's no set in stone correct method.

O-Scope is good, but remember, not all have the greatest resolution to see if the wave has an irregularity. Not to mention, even if you set it for a perfect -5dB or -10dB sine wave, that's not what you're playing later. Music is dynamic. There are many occasions where notes are recorded at stronger reference levels than those. So in the end, you either set gain for clip free output and lackluster performance, or you set with gain overlap and enjoy more dynamic range, be get occasional soft/ moderate clipping.

Years ago, back when I bought a cheap pocket O-Scope, I found that, at least for me, I could hear when the tone changed upon 2nd and 3rd harmonics at the same time the O-Scope showed the smooth wave breaking up.

As time goes, hearing degrades, so I don't know for sure if I can still detect distortion at the same time as an O-Scope. I'll have to do some testing and find out.
 

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Each to there own , but for me this is the only way to do it correctly and the resolution is a non issue as I have a high quality digital storage oscilloscope ( I'm an electronics tech )
 

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Yep, everyone has their own preferences, nothing wrong with that, so long as one isn't ruining equipment left and right.
 

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I've never done it by ear. I have used a DMM an oscope and a DD1. For me the most accurate and reliable one has been the DD1. I faced an issue that I highlighted elsewhere on the forum with regards to having a DSP in the gain train. I know the DD1 isn't cheap, but I have found it to be reliable. Use a 0db to find max headunit volume, then use -5db and -10db for setting the gains. Light turns red if there is distortion, just back down and light goes off, your done.
 

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I've never done it by ear. I have used a DMM an oscope and a DD1. For me the most accurate and reliable one has been the DD1. I faced an issue that I highlighted elsewhere on the forum with regards to having a DSP in the gain train. I know the DD1 isn't cheap, but I have found it to be reliable. Use a 0db to find max headunit volume, then use -5db and -10db for setting the gains. Light turns red if there is distortion, just back down and light goes off, your done.
The DD-1 is the one tool I've never used to set gain. I've tried pretty much every other method I have found. I'd like to get a DD-1 and compare all the different ways to set gain head to head to see if there is a clear winner or which methods are best to avoid. Sadly, I just can't justify $190 just to (most likely) prove the DD-1 isn't any better and in such, is vastly over priced as a one trick pony.
 
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