BUILD A CHEAP AUDIO SYSTEM, PART 2, OHMS!!!!
Cars & Trucks March 7th, 2008
SINCE MY PREVIOUS GUIDE WAS SUCH A HIT I’VE DECIDED TO WRITE ANOTHER. I GOT MANY EMAILS REGARDING OHMS AND WHAT THE HECK THEY ARE. SIMPLY PUT OHMS ARE THE SPEAKERS RESISTANCE TO THE AMPLIFIER POWER BEING PUMPED INTO IT. MOST AVERAGE CIRCUIT CITY AMPS REQUIRE A 4 OHM LOAD. THAT MEANS FOR A 2-CHANNEL AMP EXAMPLE YOU CAN RUN SAY A PAIR OF 6X9′S THAT ARE RATED AT 4 OHMS. BUT LETS SAY YOU WANT TO RUN A SUB AND YOU GOT A SWEET DEAL OFF EBAY ON A DUAL VOICE COIL SUB, WHICH IS ESSENTIALLY 2 SUBS IN ONE BUT THEY ARE 2 OHMS PER EACH COIL. THE SITUATIONS YOU HAVE NOW IS OBVIOUS THE AMP IS RATED AT 4 OHM LOAD. SO YES THE SUB WILL OF COURSE WORK AS MANY OF YOU OUT THERE WILL SAY “I’M DOING THAT RIGHT NOW” AND I’LL PUT MONEY ON IT THAT THE THING POUNDS BUT ARE YOU AWARE THE AMP IS SLOWLY COOKING? THAT SUB HAVING LOWER OHMS THAN THE AMP REQUIRES MEANS THAT THE POWER IS FLOWING OUT OF THE AMP BASICALLY HOW I SHOULD SAY TOO “FAST” AND ALLOWING THE AMP TO HEAT UP WAY BEYOND IT’S INTENDED TEMPERATURE AND EVENTUALLY IT OVERHEATS SO BAD IT COOKS ITSELF, AND WILL COOK THE SUB TOO IF NOT CAUGHT RIGHT AWAY. SO NOW YOU WANT TO FIX THIS AS BEST YOU CAN WITH WHAT YOU HAVE SO YOU THINK YOU ARE STUCK, NOT SO. DID YOU KNOW THAT YOU CAN WIRE THE SUB IN SUCH A WAY AS TO TRICK THE AMP INTO THINKING IT IS PUSHING 4 OHM EVEN THOUGH YOU HAVE A DUAL COIL SUB AT 2 OHM EACH?? THIS IS CALLED SERIES WIRING. WHAT YOU DO IS TAKE YOUR AMPS OUTPUT AND PUT IT INTO THE SUBS FIRST COIL THEN TAKE THAT NEGATIVE SIDE OUT AND PUT IT TO THE OF THE NEXT COIL AND TAKE THAT NEGATIVE YOU HAVE LEFT BACK TO THE AMPS - OUTPUT. WITH A TEST METER YOU CAN SEE NOW YOU HAVE CREATED A 4 OHM LOAD(OR VERY CLOSE TO 4 OHM’S)NOW SINCE YOU ONLY HAVE ONE OF THESE SUBS BUT AMP IS 2 CHANNEL YOU WANT TO GET ALL THE POWER OUT OF YOUR AMP, THIS IS WHERE THAT BRIDGEABLE TERM ON YOUR AMP COMES IN. BY CONNECTING THE OF SUB TO LEFT POSITIVE AND THE - OF SUB TO RIGHT ON AMP(SOME AMPS VARY ON WHERE TO CONNECT TO GO BRIDGED, READ YOUR MANUAL) YOU WILL COMBINE ALL THE AMPS POWER INTO ONE CHANNEL. AND MOST REGULAR AMPS WILL DO 4 OHMS BRIDGED, VERY FEW DO ANY LESS ON THE OHMS IN BRIDGED MODE. EVER SEE FANCY CARS WITH TONS OF SUBS? WELL THEY DO THE SAME FANCY SERIES/PARALELL WIRING AND EACH SUB THEY ADD REDUCES THE OHMS BY HALF. SO SAY YOU GOT A 1 OHM STABLE AMP YOU COULD BUY 4 SUBS AT 4 OHMS EACH AND WHEN ALL WIRED IN PARALLEL YOU NOW HAVE A 1 OHM LOAD FOR AMP. NOW DONT ASK ME WHY, THE TECHNICAL SPECS ON OHMS IS SO COMPLICATED IT CANT BE EASILY EXPLAINED, JUST NOW IF YOU HAVE EVER WONDERED WHY THAT OLD AMP YOU USED TO HAVE JUST DIED, OR WHY THERE ARE LOTS OF AS IS AMPS ON EBAY THAT SAY POWERS UP, BUT NO OUTPUT I CAN PROBABLY GUARANTEE SOMEONE WAS RUNNING THE WRONG OHM LOAD ON THE AMP SO IT IS COOKED!! PLEASE VOTE IF YOU FOUND GUIDE HELPFUL OR INFORMATIVE!!
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