Did 2ohm Sub Make This Fosgate Blow?

[zenhog]

Puzzling question. My installer used the fosgate p5002 (2 channel bridgable) to run my single Type R sub speaker.

That speaker has two 4ohm coils wired in series so it draws at 2 ohm. CORRECTION: I DON'T KNOW EXACTLY HOW IT'S WIRED I JUST KNOW IT'S AN ALPINE TYPE R 10" SUB WITH TWO 4 OHM VOICE COILS THAT RUN AT 2 OHMS

The fosgate spec says it runs in bridged mode at 4 ohms.The amp would cut out (I couldn't see it while driving to see if it was the protection mode or thermal mode cutout) and would come back after a while but by the end of the second day seems blown. When you put the speaker wires to the leads the speaker pops once and that's all that happens.

The installer said we're trying to drive the speaker to a volume that forced the amp to blow, even though in other applications he's used that combination without a problem.

Make sense?

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[Blunt 10+ year member]

you using the wrong amp with that sub. if its only stable to 4 ohms bridged you can't run a 2 ohm load on it and expect it to handle it. The cutting out was the amp not being able to stay stable at 2 ohms. Sounds to me like you need a different amp.

 

[Darth Audio 10+ year member]

Yes it makes perfect sense. When you bridge an amp it "sees" a 2 ohm load. The way your sub was wired the amp was running at 1 ohm. Not good for the amp at all.

BTW if the if the voice coils were wired in series the ohm load would've been 8 not 2. Your sub was wired in parallel.

 

[swimfreak26 10+ year member]

Yes it makes perfect sense. When you bridge an amp it "sees" a 2 ohm load. The way your sub was wired the amp was running at 1 ohm. Not good for the amp at all.

His amp was not seeing a 1 ohm load, it was seeing a 2 ohm final load. The subs wired in parallel drop the net impedence to 2 ohms, then he bridged the two channels together to get more power out of the amp.

This produces the same effect as wiring two 4 ohm subs to a mono amp that internally "bridges them."

Now, despite the fact that you were only dropping to a 2 ohm load, the amp is only stable to a 4 ohm load when running the channels bridged, so, bye bye amp.

 

[PatFitz9 10+ year member]

if you wire 2 4 ohm coils in series you get 4 + 4 = 8... where did the 2 ohm load come from? i think you need to clarify the first post to figure out the problem.

 

[Darth Audio 10+ year member]

If the ohm load on the amp was 2 and he then bridged the amp the amp sees a 1 ohm load.

 

[Cbass 10+ year member]

If the ohm load on the amp was 2 and he then bridged the amp the amp sees a 1 ohm load.

//content.invisioncic.com/y282845/emoticons/eyebrow.gif.fe2c18d8720fe8c7eaed347b21ea05a5.gif ???

 

[Cbass 10+ year member]

If the sub is dual 4 and was wired in parallel and then briged then the amp saw 2ohms final load and cause is a 4ohm stable amp (bridged mode) it died.

perfect sense

 

[Blunt 10+ year member]

If the ohm load on the amp was 2 and he then bridged the amp the amp sees a 1 ohm load.

how do you figure 1 speaker dual 4 ohm so wired to a 2 ohm load . If you bridge the amp guess what that doesn't change the ohm load cause you never changed the speaker its still a single dual 4 that can run either an 8 or a 2 ohm load no others. Read rather then respond

 

[Darth Audio 10+ year member]

This is getting too complicated. If you take any amp and bridge it the amp thinks it is running a lower ohm load. If you hook a 4 ohm sub to an amp that is bridged the amp thinks it is running a 2 ohm load, simple. So what I said in my first post is correct, the amp thinks it is running at a 1 ohm load because it was bridged and presented with a 2 ohm load. Learn rather than respond.

 

[Blunt 10+ year member]

This is getting too complicated. If you take any amp and bridge it the amp thinks it is running a lower ohm load. If you hook a 4 ohm sub to an amp that is bridged the amp thinks it is running a 2 ohm load, simple. So what I said in my first post is correct, the amp thinks it is running at a 1 ohm load because it was bridged and presented with a 2 ohm load. Learn rather than respond.

how does bridgeing the amp change the ohm load.

if the sub is 2 ohm load the amp can't change that PERIOD.

I bet if he checked the speaker wires at the amp with a dmm it would read 2 ohms not 1 ohm.

Perhaps you should do a little more research JACKASS

The amp thinks its running at a 2 ohm load well because IT IS

Otherwise i'd fry every amp i own because they are designed for 2ohm bridged and i hook a dual 4 up to them so they must be running 1 ohm right well then i guess they will fry soon.

 

[Darth Audio 10+ year member]

You can say what you need to say without being an an A$$. You are not getting what I'm saying. Bridging the amp doesn't change the ohm load. But the amp thinks it does because you bridged from 2 channels to 1. I cannot make it any clearer and your not gonna listen to me anyway so check the internet it's free. These forums are to help each other and not argue so I hope you'll consider that when you respond.

 

[ChuteBoxe515 10+ year member]

darth--only read your first post, but, no matter what you do, you cant wire a DVC4 sub to a 1 ohm load

 

[Bumpin' Yota 10+ year member]

Yes it makes perfect sense. When you bridge an amp it "sees" a 2 ohm load. The way your sub was wired the amp was running at 1 ohm. Not good for the amp at all.
BTW if the if the voice coils were wired in series the ohm load would've been 8 not 2. Your sub was wired in parallel.

You really need to work on explaining your concepts. A 2 channel amp is really 2 monoblocks in one case - obviously they can be bridged to 4ohm mono. In this scenario each of the monoblocks is seeing 2 ohms.

As you said, if he paralleled the voice coils, he would have a 2ohm mono load. This combined with the amp being bridged and each monoblock inside of the amp sees 1ohm. However the amp, meaning both monoblocs in one case, will be seeing 2ohm mono. //content.invisioncic.com/y282845/emoticons/wink.gif.608e3ea05f1a9f98611af0861652f8fb.gif

 

[Bumpin' Yota 10+ year member]

His amp was not seeing a 1 ohm load, it was seeing a 2 ohm final load. The subs wired in parallel drop the net impedence to 2 ohms, then he bridged the two channels together to get more power out of the amp.
This produces the same effect as wiring two 4 ohm subs to a mono amp that internally "bridges them."

Now, despite the fact that you were only dropping to a 2 ohm load, the amp is only stable to a 4 ohm load when running the channels bridged, so, bye bye amp.

Actually he is correct - each channel is seeing 1ohm if he's running the amp at 2ohm mono