Blown speaker fuses

keith allen

I have a neighbor that has a pair of Cerwin Vega D9's,big 4ohm speakers.He was running them of a multi channel receiver...HK 65watter,didnt sound all that good,and ya know,it got very hot.He scored a Parasound hca1000 off the Bay,hooked it up they did sound a good bit better but after playing them a while,both 2amp fuses blew in the speakers,they never did that when running off the receiver,any idea what may of caused that to happen,think the amp could have a problem?

faster100

I think going from 65 watts to 125 clean watts and he overpowered them, more then likely got the new amp, and figured it should "crank" on those CV 9's and blew the fuses.. better the fuse then the tweeters...

keith allen

I understand what your saying,but these speakers have a max rating of about 350watts...could they still be over powered by that small amp?

faster100

I'm not sure when they were made, but speakers from long ago sometimes had inflated wattage handleing specs... and if he was clipping the amp, he could have blown the safety fuse and it did what it was suppose to.. if they did indeed handle 350, thats clean watts, 125 clipped would blow the fuse... IMO

bknauss

Originally posted by faster100
I'm not sure when they were made, but speakers from long ago sometimes had inflated wattage handleing specs... and if he was clipping the amp, he could have blown the safety fuse and it did what it was suppose to.. if they did indeed handle 350, thats clean watts, 125 clipped would blow the fuse... IMO

"Clipped watts" won't blow a fuse. If you're comparing 125 clean W to 125 clipped W, its the same amount of power. What happens if you take an amp that does 125W clean, then clip the heck out of it, it'll do a LOT more power output (think of the area of a clean sine wave vs a square wave... square wave takes up more area, therefore more power).

2A fuses sound pretty weak to me. Subs amps usually have voltage rails of 45V-60V, so P=I*V means you're getting 90W-120W max before the the fuse blows.

keith allen

I'm stumped

bknauss

I say put a bigger fuse in it

Tour2ma

It's likely that the Voice coils in the CV's heated up after being driven for a while (at what I am sure were levels the HK pushed them to).

As VC's heat, impedance drops. As impedance drops, current must increase to sustain power, perhaps it rose to the point of the fuses' rating, but this is not very likely.

More likely is that the above occured and the Parasound finally ran out of current and clipped. When clipping occurs the amp produces "direct current" and this is what normally blows speaker fuses. I say this is more likely because both speakers blew fuses at the same time...

Replace the fuses with the same ones they had, 2 ampere. It's likely they are "Slo-blo", but pay attention to the blown ones indication on this count as well (slo, normal or fast). And tell your friend to exercise a little restraint.