Subs keep blowing

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kiteman

Copper - Posts: 98

Joined: January 14, 2004

Location: United States

Posted: April 19, 2004 at 10:54 AM / IP Logged

A friend has a boss monoblock 1100 amp, and he has 2 12" power acoustic dual 4 ohm subs. The subs are wire up to Parallel so as to bring them to a 1 ohm load. The subs are also mounted reverse in the box. He seems to blow a sub a week? anyone have any ideas?

DYohn

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Joined: April 22, 2003

Location: Arizona, United States

Posted: April 19, 2004 at 11:06 AM / IP Logged

Lots of ideas, including low quality build on those brand names, but the most likely is the amp is clipping heavily due to gain being set incorrectly, and/or the enclosure is way too big.

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kiteman

Copper - Posts: 98

Joined: January 14, 2004

Location: United States

Posted: April 19, 2004 at 12:38 PM / IP Logged

The box is about 1 to 1.25 prefabe box, would it have anyting to do with the subs being mounted in rev. ? Also what does the phase button do?

kickerstang

Copper - Posts: 180

Joined: April 08, 2004

Location: United States

Posted: April 19, 2004 at 12:42 PM / IP Logged

when a sub is inverted it is basically playing backwards. phase is used to control this, being inverted shouldn't have anything to do with the subs blowing

what!?!?! you want some??

southside

Copper - Posts: 220

Joined: March 08, 2004

Location: United States

Posted: April 19, 2004 at 1:08 PM / IP Logged

remember that he has to reverse the wiring if he has the magnet out of the box too. so postive would go to neg an so on. from what i read on here that is what u have to do.

southsider

DYohn

Moderator - Posts: 10,741

Joined: April 22, 2003

Location: Arizona, United States

Posted: April 19, 2004 at 1:15 PM / IP Logged

With the subs inverted, they add about 0.1 cuft to the enclosure volume, so at worst you are at 1.3 cuft. Is this per sub or is it shared by the two? I strongly suspect the amplifier is clipping, probably because it is being over-driven or the gain is way too high. A boss amp is about 50% over-rated, so your "1100 watt" amp is probably more like 500 watts, so he may have cranked it up trying to get more out than it is actually capable of delivering. RESET THE GAIN!

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forbidden

Platinum - Posts: 5,352

Joined: November 01, 2003

Location: Alberta, Canada

Posted: April 19, 2004 at 1:25 PM / IP Logged

I smell.......CLIPPING.....anyone else?

Top Secret, I can tell you but then my wife will kill me.

kiteman

Copper - Posts: 98

Joined: January 14, 2004

Location: United States

Posted: April 19, 2004 at 1:32 PM / IP Logged

When you say clipping, wouldn't the amp be shutting down into protecting mod, and the cumming back on? And Kicherstang you mentioned that fhase would control this? The phase switch on the amp and controls the RCA outputs coming out of the amp right? Also southside mentioned wiring up the speakers up backward is that the right way? Thanks

DYohn

Moderator - Posts: 10,741

Joined: April 22, 2003

Location: Arizona, United States

Posted: April 19, 2004 at 1:40 PM / IP Logged

No, a car audio amp will not shut down if it is clipping - well, some very expensive ones actually have clipping detenction circuits in them, but BOSS does not and they are VERY prone to clipping. This will fry your speakers. TURN DOWN THE GAIN! Set it properly.

A phase switch on an amp or crossover will do the same thing as swapping the wires at the woofer. Turns + in - and vice versa.

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forbidden

Platinum - Posts: 5,352

Joined: November 01, 2003

Location: Alberta, Canada

Posted: April 19, 2004 at 1:41 PM / IP Logged

Throw phase out the window, it has no place in blowing a sub for this discussion. No an amp will not shut down due to clipping (unless it has a really really amazing protection circuit - not in this amp though). Wiring up the speakers backwards is also a phase issue and again it will not be affecting our outcome.

Are you familiar with clipping and what it is and the same for phase?

Top Secret, I can tell you but then my wife will kill me.

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