question on gain setting?

[liftedcj7on44s 10+ year member]

ok i have a infinty reference 1211a amp. i downloaded a 0db 50hz test tone at realm of excursion. pop the cd in the reciever. i disconnect my sub and stick my voltmeter in the amps speaker terminals. i start with 0 bass on the HU and 0 bass boost on the Amp, crossover set to about 80hz. starting with the gain all the way down and im shooting for a target voltage of 44.7 volts( sub is wired at 2 ohm so this should yield 1000 rms) start raising the gain on the amp, o HU vol is on 40 out of 62. so im raising the gain on the amp and i reach 44 volts. but wait the gain is almost maxxed out!!!!! well im at 44 volts so i reconnect my sub and go to play some music form either the radio or a cd. well when i do that with the HU vol at the same level that i had it when i set 44 volts the amp clips all to hell and my sub sounds like its about to blow all to bits. i lower the gain back down and dont have much output then. whats the prob here?

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[Biker 10+ year member]

Are you sure you have a 2 ohm load? Check the subs at the amp to see if there total load on the amp is 2 ohms with your DVM.

Are you checking the voltage for AC voltage?

Is your DVM at True RMS meter?

Your setting your gain with 0 bass and 0 bass boost. Are you playing the music with those same settings?

Are your subs rated for 1000 watts. IE: 2 subs rated @ 500 rms each?

Also you say your setting up the crossover at 80 hz. Thats fine for the test tone but try lowering it to 50 or 60 when you play music.

What voltage are you running? make sure you have enough power from your battery and charging system.

 

[XanderMoser 10+ year member]

The problem is the method you used to set your gains. Don't use the formula and DMM method, it is flawed for a number of reasons. Number one being that the ratings on amps and subs are almost always over or underrated. You never know what you're dealing with. Set the gains by ear instead. Some people use music, some people use test tones. I prefer music because test tones can be very hard on a speaker. So beware. Lower your gain all the way. Turn your HU up to the maximum volume that you listen to it, make sure there is no distortion. Now raise the gain on the amp until you hear distortion in the sub, then lower it a bit. You're good now.

 

[liftedcj7on44s 10+ year member]

Its a idmax 12 amp shows its pushing 1000 watts but it sounds like a xplod 12 getting 300 watts

 

[diminishedpower 10+ year member]

ya i might get flamed or what not but way i set gains for the exact reason as stated above is i set all my setting to max i ever would use, so like bass is +2 for me and volume at 40, then i play a -3 db test tone. And last i just turn up gain until i hear distortion then turn it down a bit. In 3 years i've never blown a sub.

 

[wolfman1966 10+ year member]

just wondering, why a -3db test tone, I always heard use a regular 50hz test tone.

 

[liftedcj7on44s 10+ year member]

I dont get any distortion just massive amp clipping and a sub that sounds like its about to fly apart. but like i said when i get 1000 watts while playing music its not loud at all.

 

[profundus-sanus 10+ year member]

i use dmm and test tone....because i buy headroom.

for an untrained ear the dmm method is far safer.

did you do this with the car on?

i know for some reason when i tried to set the gain on my hk with the car off it would maxx out at 65volts.... turn the car on and wham...130 volts from the same gain setting.

 

[diminishedpower 10+ year member]

just wondering, why a -3db test tone, I always heard use a regular 50hz test tone.

No thats two diff things im talking about , hz test tones come in diff varieties. 0 db -3 db -6 db and -10 db are the most common. And for hertz i start off at a 50hz -3 db test tone but i go all way down to 30 hz -3db at 5 hz steps when doing by ear to make sure there isn't any distortion throughout the whole spectrum the sub will play.

And for liftedcj, clipping is the distortion were talking about. Is the amp brand new or did you buy it used?

Also double check you have everything wired correctly including the sub at correct ohm load.

Last what HU are you using?

 

[liftedcj7on44s 10+ year member]

Yes car on every time im not very happy. its sounds like i got a el-cheapo 12 runnin off 300watts

 

[diminishedpower 10+ year member]

i use dmm and test tone....because i buy headroom.
for an untrained ear the dmm method is far safer.

did you do this with the car on?

i know for some reason when i tried to set the gain on my hk with the car off it would maxx out at 65volts.... turn the car on and wham...130 volts from the same gain setting.

Well all gain setting should be done with car running period. Or else your not having alt supply power and decreasing input voltage.

 

[wolfman1966 10+ year member]

No thats two diff things im talking about , hz test tones come in diff varieties. 0 db -3 db -6 db and -10 db are the most common. And for hertz i start off at a 50hz -3 db test tone but i go all way down to 30 hz -3db at 5 hz steps when doing by ear to make sure there isn't any distortion throughout the whole spectrum the sub will play.
And for lifted cliping is the distortion were talking about. Is the amp brand new or did you buy it used?

Also double check you have everything wired correctly including the sub at correct ohm load.

Last what HU are you using?

I knew that, I was just wondering why u used a -3db test tone instead of a 0db one.

and for all its worth, I set mine by ear using a 50hz 0db test tone. However, I just recently raised my LPF filter setting slightly, and then redid the gain setting, and for some reason everything sounds louder now.

 

[diminishedpower 10+ year member]

I knew that, I was just wondering why u used a -3db test tone instead of a 0db one.and for all its worth, I set mine by ear using a 50hz 0db test tone. However, I just recently raised my LPF filter setting slightly, and then redid the gain setting, and for some reason everything sounds louder now.

Good chance where you had your LPF set at it was cutting off some of your upper end, or the other thing is higher notes sound louder, your subs aren't louder they just sound like it because there playing higher frequencies.

And as for the -3 db thing its stated best in the gain setting tutorial but short answer is music will never hit 0 db so you are losing some sound, highest that notes have seen is -3 within music so even on those songs i wont be clipping, so i get more performance at my top sound by using -3 db. Some use -6 db because that -3 db is very rare to hit, and when set at -6 db tuning the only time you clip is on the quick notes that hit -3 db and so you get more performance but subs slightly clipping on some rare songs. Thats why i choose -3 db more performance over 0 db and very rare still to clip.

Guess that wasnt so short

 

[liftedcj7on44s 10+ year member]

Everything is wired correctly using a fluke. amp is used. why is my sub sounding like its about to explode when the amp clips. its no where near full excusion

 

[diminishedpower 10+ year member]

well have you turned down the gain because if your using a halfway decent headunit you will never need to turn gain past half way. Have you used the amp before this? there is a chance that some of the output mosfets but not all are blown, so you get some output not full. I had this happen in a trade, the guy ripped me off, i had to get the amp repaired. Have you double checked rca's are getting full connection everywhere?