how to tune an amplifier??

**2dee11** · 04-22-2012

i am so confused on how to tune my amplifier using a digital multi meter?

i am using a hifonics brutus 1200 amplifier

the settings it has are "level" (which i think you are supposed to match to the output voltage of your head unit) "phase" "remote" (wired to a remote box in the front of the car that goes from max to min) "bass eq" "sub sonic" and "low pass"

i looked in my head units owners manual and it says "preout maximum output level 2.0v" so im guessing that i set the level to 2.0v but im not sure how you do this when its on a dial from .02v to 9v

if there is any other info you need i will do my best to give it to you

thanks for the help!

**Fatboy501** · 04-22-2012

How To: Set your Amplifier Gain - SSA Car Audio Forum

As for your Sub Sonic filter, what kind of enclosure do you have? If ported, a lot of people recommend setting it a little bit under tuning... for instance, if your enclosure is tuned to 35hz then set the SSF @ 30hz. If sealed, most people just leave it off, or turned to the lowest setting. I leave mine off period, because music I play tends to dip rather low. As for bass knobs... I usually just leave them unhooked. Phase is referring to your + and -.... sometimes people reverse the polarity to help the subs response if it seems slightly behind the rest of the music... some headunits can control this as well. It's sometimes used as a bootleg time-alignment. Low pass is your low-pass filter... basically whatever you set that at, frequencies lower than that will be passed on the the subwoofer. I usually set mine around 60hz, but some people like their subs to play higher than that.

**2dee11** · 04-22-2012

so should i just leave phase on 0 degrees? and sub sonic to 15hz? (knob goes between 15-35hz)

**Fatboy501** · 04-22-2012

What kind of box are you using? Sealed, ported, bandpass? If ported, what is the enclosure tuned to? What sub? What kind of music do you primarily listen to? Yes, you can leave phase on 0.

**2dee11** · 04-22-2012

okay so for the gains, each one of my subs ( i have dual 12's) is 50-150 rms. so since the amp goes up to like 900x1 at two ohms so thats what 450 to each speaker? i should use the speaker rms for my calculations so i dont over power them?

**I800C0LLECT** · 04-22-2012

Graphing Trig Functions: Phase Shift

When people are changing phase they are trying to align the amplitudes of the signal. When two signals(two speakers) are 180 degrees out of phase with each other they cancel each other out. Therefore you flip polarity to reverse the amplitude/align the phase. Reversing polarity is a elementary way of doing that. Because it flips the amplitude of the signal that means it delays the signal by half the phase length adding a rudimentary time delay.

Because each frequency has it's own wave length phase and shift are not even across the board. You're typically only aligning one frequency.

**Fatboy501** · 04-22-2012

Yes, using your speakers' RMS would be the correct way for you to do this.

**Fatboy501** · 04-22-2012

Originally Posted by I800C0LLECT

Graphing Trig Functions: Phase Shift

When people are changing phase they are trying to align the amplitudes of the signal. When two signals(two speakers) are 180 degrees out of phase with each other they cancel each other out. Therefore you flip polarity to reverse the amplitude/align the phase. Reversing polarity is a elementary way of doing that. Because it flips the amplitude of the signal that means it delays the signal by half the phase length adding a rudimentary time delay.

Lol yeah that... I just call it bootleg time alignment lol.

**2dee11** · 04-22-2012

Originally Posted by Fatboy501

What kind of box are you using? Sealed, ported, bandpass? If ported, what is the enclosure tuned to? What sub? What kind of music do you primarily listen to? Yes, you can leave phase on 0.

i have a sealed box. both subs are 4 ohm SVC rated at 50-150 RMS 800 MAX. i primarily listen to rap

**Fatboy501** · 04-22-2012

Well, yes, you can leave the SSF at 15... but, idk, with Dual subs, I'd set it right under 30ish Hz just to be safe.

**2dee11** · 04-22-2012

Originally Posted by Fatboy501

Well, yes, you can leave the SSF at 15... but, idk, with Dual subs, I'd set it right under 30ish Hz just to be safe.

i thought you said with sealed box you should just leave it all the way down or off?

**I800C0LLECT** · 04-22-2012

Originally Posted by 2dee11

i thought you said with sealed box you should just leave it all the way down or off?

True...sealed will have a roll off and it wouldn't matter in majority of cases. You usually want to add a filter if you're attempting to use EQ to boost the lower end of the sub output and I would suggest putting the infrasonic filter at just below the Fs of the speaker and hopefully it's a 24 decibel slope

**Fatboy501** · 04-22-2012

I did, and you absolutely can, but I don't know how much low-note abuse those Duals are going to take as I've never messed with them. Besides, I doubt anything you play will go much below 28hz, which is was the low note in "Put On" is if the song is not altered.

EDIT: What he said. I just tend to be very careful with other people's equipment when recommending settings, and I've honestly never used a Dual subwoofer.

**2dee11** · 04-22-2012

so should i put it to 30ish?

**Fatboy501** · 04-22-2012

I would... but I800 knows a lot more about sealed enclosures than myself... so... yeah go with him on this one.

**I800C0LLECT** · 04-22-2012

Fatboy knows more than I do about subs...I won't be shy

I say put it on 30hz until you know what the Fs of the T/s parameters tell you

**2dee11** · 04-22-2012

Voltage of the output = sqrt(RMS Power X impedance of the speaker)

Example
Say the amp provides 100WRMS into a 4 ohm speaker:

Voltage = sqrt(100W X 4 ohms)
Voltage = sqrt(400W*ohms)
Voltage = 20V

am i doing this correctly??
Voltage of the output = sqrt(RMS Power X impedance of the speaker

Speakers are 150 RMS a piece so 150x2 is 300 and they are 4 ohm speakers:

Voltage = sqrt(300W X 4 ohms)
Voltage = sqrt(1200W*ohms)
Voltage = 34.64101615137755 V

or should i do 2 ohms because its a mono amp and they are wired as such

this is also confusing because the amp instructions says to match the radio output sensitivity for the level and my radios maual says 2.0v is its output

**I800C0LLECT** · 04-22-2012

I thought you were supposed to supply a set frequency/sine wave to the amplifier when you're measuring signal strength? Then you set the gain according to that? i.e. volume knob at ~80% with a 100hz sine wave. Use your DMM and the rest is math and gain knob?

EDIT: http://www.jlaudio.com/header/Suppor...Setting/287546

I know fatboy gave a link but sometimes different pictures make things click for different people