Question about distortion... (glass or someone help plz)

 

Bronze Member
Username: Letto

Milwaukee, WI

Post Number: 75
Registered: Jun-05
OK, I have 2 Image Dynamics IDQ10D4 V.2's (300W RMS)powered with a Rockford Fosgate 501S (500W RMS x 1 @ 4 ohms bridged). I have the subs wired series/parallel to give me a 4 ohm load, and then bridged on the amp.

How do I know if my subs are distorting bad? Should this amp be able to distort/blow these subs since the RMS on the amp is only 500 (250 to each sub) and the RMS on each sub is 300... Just wondering because I don't really want to ruin these subs since they're brand new and I don't know if/dont think the gains are set properly on my amp. I think when my original system was installed (a few years ago) the people at American might have just maxed the gains to make it louder since at that time I was running like 4 JL W0's off it, and didn't know how to install stuff myself. Since then everything I have got new, I have installed myself.

Any help would be appreciated
 

Gold Member
Username: Glasswolf

Wisteria, Lane USA

Post Number: 7987
Registered: Dec-03
you should hear distortion before it causes any damage. popping, bottoming out, scratchy.. you'll know distortion when you hear it.
it sounds a lot like taking any little clock radio and turning it up too far till the audio gets all crappy.
 

Bronze Member
Username: Letto

Milwaukee, WI

Post Number: 77
Registered: Jun-05
Thanks,

Do you think I should have to worry much about it with the amp I currently have since the RMS power is less than my speakers should be able to handle? Even if the gains are maxed, which I'm not sure of, and don't want to mess with since I'm still not too sure about adjusting them.
 

Gold Member
Username: Glasswolf

Wisteria, Lane USA

Post Number: 7996
Registered: Dec-03
having the gains set too high causes DC voltage to go to the coils of the speakers.
this causes heat to build up in the coils, and can fry them even with less than "rated" power, since the rated power handling is measured with AC voltage and no clipping.
 

Bronze Member
Username: Letto

Milwaukee, WI

Post Number: 78
Registered: Jun-05
What do you recommend I do? I don't have any instruments to measure the voltage output from my HU, and even if I did, the gains on my amp are 2 little knobs that turn one full turn. No numbers or anything like that around them.
 

Gold Member
Username: Glasswolf

Wisteria, Lane USA

Post Number: 8005
Registered: Dec-03
until you can get someone to set them properly for you then, don't turn them up past about one quarter turn.
that's a good safe zone to stay within.
if the amps aren't loud enough at that level, you need bigger amplifiers.
 

Bronze Member
Username: Letto

Milwaukee, WI

Post Number: 79
Registered: Jun-05
Is there a way to figure out how much of a turn equals 1 V or something? That way if I do figure out how much voltage my HU is outputting I could set them.
 

Gold Member
Username: Glasswolf

Wisteria, Lane USA

Post Number: 8008
Registered: Dec-03
not without a signal generator, a meter, and a scope, not really
 

Bronze Member
Username: Letto

Milwaukee, WI

Post Number: 81
Registered: Jun-05
Thanks glass
 

Bronze Member
Username: Phuktupbasshead

Scottsdale, Arizona United State...

Post Number: 93
Registered: May-05
you mentioned clipping... what's that?
 

Gold Member
Username: Glasswolf

Wisteria, Lane USA

Post Number: 8070
Registered: Dec-03
http://www.bcae1.com/2ltlpwr.htm
that explains clipping pretty well.
it's when the sine wave signal from the amplifier in your case, turns into a square wave due to the peaks of the wave being "clipped" off from lack of sufficient voltage.

this is what kills speakers 9 times out of 10.
 

Bronze Member
Username: Letto

Milwaukee, WI

Post Number: 88
Registered: Jun-05
Hey glasswolf, I read over that webpage and have a question.

When adjusting the gains on my amplifier I noticed that they seem to do almost nothing until I get close to maximum, then all of a sudden the gains are exponential... is this most likely the point that the signal is turning into a square wave?

Also, my amplifier overheats pretty much everytime i listen to it at high volumes for more than 15ish minutes... I have my speakers wired to 4 ohms and my amp does the most power (500W RMS) at 4 ohms bridged... it should not overheat doing that, correct? Do you think it is a problem with the amp? Pretty much every place I have asked someone, and even one guy who took a look at it said it is most likely a problem with the amp. Is there a way to fix it, or will I just have to get a new one?
 

Gold Member
Username: Glasswolf

Wisteria, Lane USA

Post Number: 8100
Registered: Dec-03
does sound like a bad amp between the gain problem and the shutting off.
you'd need to find a repair center for that amp brand to get it fixed.
the tech will need the schematics for the amp and those can be hard to get unless the place doing the work is authorized by the maker.

amps put out the same power x 1 @ 4 ohms bridged as they do combined x2 @ 2 ohms by the way.
just a matter of what load you're giving the amp to get that power.
 

Bronze Member
Username: Letto

Milwaukee, WI

Post Number: 89
Registered: Jun-05
Do you think I should try wiring the speakers each seperately to 2 ohms and not bridge them and see if that helps?
 

Gold Member
Username: Glasswolf

Wisteria, Lane USA

Post Number: 8103
Registered: Dec-03
if ya like. that may help but I'm doubtful. worth a shot though
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