speaker impedance

djnrg98 · Post by **djnrg98** » Fri Oct 05, 2007 9:07 am

Hi All,

I'm having problems with my amp taking up waaaay to much power in my car. Even with a 200amp alt (used to be a 120) , 3farad caps, 1000cca batter, 0gauge wire/ground (used to have 4 gauge), I get voltage drops each time the bass hits when I crank the amp up. I've been to 4 stereo shops, I'm pretty good with electronics myself, and I have still not been able to figure things out. I've been over absolutely everything, and now am suspecting the speakers. I think theres a short in them, and the impedance is going to near zero (or maybe even zero) with enough excursion. I should also mention that I have tried 3 different amps (one PG, one Rockford, and one Earthquake) all with the same results - voltage drop which kills my alternator, and overheats all 3 of the different amps I tried. So, thus, I suspect the speakers as they have been kept constant all along.

What is the lowest impedance I should get with the speaker at full forward excursion? I will test it this weekend to see what I get. I have the titanium 12" speakers. To be honest, I forget if they are SVC or DVC (havent opened up the box in years), but I get 3.8ohms out of each speaker speaker when off/idle.

I know there used to be spec sheets, but not sure if they had the max/min impedances or not. Either way, I cant find the spec sheets on the new PG web site.

Thanks!

-James

Post by **fuzzysnuggleduck** » Fri Oct 05, 2007 10:05 am

Have you taken any DMM measurements across various points in electrical system such as resistance? Do you know everything all the way to the speaker is performing as expected for a fact?

Post by **Francious70** » Fri Oct 05, 2007 10:16 am

Try checking your gains, sounds like you may be clipping your amps, which makes them about 75% less efficient than normal.

djnrg98 · Post by **djnrg98** » Fri Oct 05, 2007 11:44 am

Hi guys, thanks for the replies.

Yes, I've tested the resistance with the various wires, grounds, changed fuses, fuse holders, and even through the body of my car. Nothing out of the ordinary...

Now the clipping is an interesting suggestion. I do run my amp gain very high, (prob all the way up actually), as I do not have a line driver. Could this cause THAT much more power draw when I (try to) crank it?

I don't really want to spend more money on a line driver if I don't have to, as its "loud" enough without the line driver and the gain all the way up. However, if you think that is causing this massive power surging, then I'm all for it. I have a new (smaller) car too, so maybe some shorter and better RCA wires would help along with the line driver? What do you think?

Come to think of it, this is the 2nd set of speakers I have tried as well. (tried a friends PG titaniums) and unless all the TI speakers are screwed up.....which I seriously doubt lol....then maybe I am clipping. After all, even with proper wiring and 2 farads of capacitance, the 600.2 Titanium amp shouldnt overload even a a stock alternator thats in good shape, correct?

Too bad there wasn't a clip light on the amps...it definitely gets hot tho when I crank it and get the voltage drop to the beat. The interesting thing is, that with hip hop music, I can have it louder (but still have the problem when I crank it) than I can with dance music, as the beats are slower, and more constant.....

Help! And thanks!

-James

Post by **stipud** » Fri Oct 05, 2007 11:59 am

Please read this
http://www.bcae1.com/2ltlpwr.htm

Gains are not a volume control... they are there to set the input sensitivity so that you can keep your amp within usable boundaries. If you have your gains cranked, odds are at high volume you are exceeding your amplifiers output capabilities on a grand scale.

http://phoenixphorum.com/gain-setting-w ... vt280.html

Post by **fuzzysnuggleduck** » Fri Oct 05, 2007 11:59 am

I agree. Check your amp's output with a DMM playing a 60Hz test tone. Sounds like clipping, especially if you're crankin' the gains.

djnrg98 · Post by **djnrg98** » Fri Oct 05, 2007 12:32 pm

The thing is, I get voltage drop even when its not that "loud." I crank it, but its certainly WAY less than what the amp can do. Also, I've seen guys with stock alternators and twice the power I have without any voltage drop. Think the clipping is causing it to create power surges to each bass hit and therefor causing my problem?
How will I tell if it's clipping? If it's over a certain voltage? What would that voltage be?

Post by **Bfowler** » Fri Oct 05, 2007 12:59 pm

its possable that even at low volume, you are still sending to high of an input voltage into the amp.

use a DMM to see what the input voltage is at at certain volumes

444 FED · Post by **444 FED** » Fri Oct 05, 2007 3:56 pm

I'm going to chime in with the obvious (to me)....

Have you done the "big 3 upgrade" yet?