DMM voltage readings?

[Apokalypz]

I just got my second 12" Infinity reff sub. I've got both of them wired to 2 OHM at the amp and they're each in their own sealed boxes. Well, I've got a 400 watt kicker amp to put a little bit of power to the subs since I don't want to throw 400-500 dollars into a more powerful amp.

Well, on to the situation. I just dropped a few test tones on a cd and went down to my car with my DMM and unhooked my subs to try to get an accurate gain setting. I've got 2 settings for AC on the DMM (750 and 200). I assume that I'm supposed to use 200 since when it's on that setting and I test my wall sockets I get ~120v. Well, I just read that for a 400 watt amp wired to 2 ohm, I should be putting 28.28 volts to my subs. Well I got it to read 28.2 on the DMM in AC200 mode and figured that was it. Then I took another look at my settings on the amp and turned my head in question. I now have my gain set to 3/4 full, the bass boost knob set down to zero, and the remote 'bass level' knob set all the way up. From what I've always had it, this is insane. I normally have the gain about half way up and the remote bass level set about 1/4 of the max. I allways tune to the volume knob at 20 on the HU with flat 0 EQs btw. So I'm like in shock that I had to set everything that high. Then the crazy part was when I plugged in the subs, started the car and then played back the test tone again, I almost went deaf. I have never heard my subs this loud before, I thought this loud would be unsafe to my equipment. And the thing is, I can't tell if it's clipping or not since it's bass and I don't have an O-scope (I'm poor) lol.

So yea, is there any flaw as to what I did to set the gains? For a while I was thinking that the decimal point in the DMM was in the wrong place, but the wall outlet test worked. So yea, I'm confused, should 400 watts at 93db sensitivity even really be loud? I have never heard my car rattle like that before in my life.

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[btdickey99 5,000+ posts]

I mean loud is too broad....loud to me and you could be two completely different things

as far as your question, it sounds like everything was done correctly. you shouldnt get any clipping if all your calculations for volt reading were correct.....

 

[digitalrainman 10+ year member]

One issue that went wrong was you listening to the test tones with the speakers plugged in. Yes it will be very loud, and from all ive read you are NOT supposed to playback test tones to actual speakers, especially with highs, or lows that are very very low.

As long as you set all the settings on your hu the way you like, then set volume to the max you want to turn to, then play test tones with speakers diconnected, that should be when you start to play with gain. If you were to keep your settings on the hu to a minimum before setting your gains, then when you do play with them you may go over the rms you are shooting for.

 

[Apokalypz]

Yea, I shot the remote bass level all the way up and the eq flat durring the gain setting so that I don't accidentally go over the rms rating of the amp. And yea, I disconnected the subs durring the time I used the multi meter to get the voltage on the sub, I was just currious as to how loud the subs are when they're getting 400 watts of power on the dot. And I can say that is loud. It renders my rear view mirror useless while I have bass hits and actually tickled the hair on my face a little.

But I mainly listen to rock so I don't get the overpowering bass too much, I just put in some rap today and it vibrates the crap out of my car when the bass hits or stays. I just never knew that 400 watts was really that powerful with the subs I have. I allways used to play it safe since I burnt out 2 sets of rear speakers (2 6x9s and 2 6.5s.) Since I've got my infinity kappa rear and fronts, I've been VERY careful with the gain setting at my max precieved volume with the mids-highs and the subs. I shall tune the mids-highs next then, I've only got them running 1.3 volts and they are capable of running 13. lol.