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Author
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Topic: Stereo help please
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Wildfire532FB
CAFords OG
Member # 1482
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posted
 
 
I installed a 4ohm sub in my 96 Explorer that came with an 8ohm sub/amp. When i turn up the volume my sub sometimes turns off depending on the music i was told its because the amp thinks there is a short with the sub since the amp is an 8ohm and the new sub is a 4ohm. How do i make the 8ohm amp think its giving power to an 8ohm sub even though its really a 4ohm?
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68 Fastback
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Posts: 17578 | From: 530 | Registered: Jun 2002
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Wildfire532FB
CAFords OG
Member # 1482
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posted
ttt
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68 Fastback
84 CJ7
94 HMMWV
95 GT
03 F350
17 Fusion Hybrid
Posts: 17578 | From: 530 | Registered: Jun 2002
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RioredGT
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Member # 2300
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posted
if the amp is designed to play at 8-ohms (8-ohm stable) than you are damaging the amp by using a 4-ohm load. With a 4-ohm load the amp sees a lower resistance and is drawing a higher current (even higher when the bass gets lower or you turn the volume up) which it is not rated for causing it to overheat which is why it is shutting down (usually amps have built in thermal protection). If you do this enough times the thermal protection circuit will eventually blow and your amp won't turn on.
As for fooling the amp into thinking it sees an 8-ohm load, I'm not too sure it's possible with one 4-ohm sub. You can get another 4-ohm sub, wire the two in series to produce an 8-ohm load and that will work.
If you want to be adventurous and try something AT YOUR OWN RISK, you can try putting a high wattage resistor (or two) in series with the sub to increase the resistance the amp sees. I've seen this done when building a low wattage speaker but never seen it done on a sub that was already built and not sure how it would effect the power of the sub???. The resistor would be something like these , but you would need to find one that matches the wattage of the amp.
[ April 19, 2009, 09:55 PM: Message edited by: RioredGT ]
Posts: 410 | From: Bay Area | Registered: Jan 2003
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Wildfire532FB
CAFords OG
Member # 1482
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posted
what if i did some kind of bridging?
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68 Fastback
84 CJ7
94 HMMWV
95 GT
03 F350
17 Fusion Hybrid
Posts: 17578 | From: 530 | Registered: Jun 2002
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RioredGT
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Member # 2300
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posted
Is it a two channel amp? Bridging is used when you combine two channels from an amp into one. Is this a factory amp or is it aftermarket? If you can post the amp specs I could possibly help you out some more...
Easiest thing might be to find an 8-ohm sub. Not as common as they used to be, but I see them from time to time on ebay.
Posts: 410 | From: Bay Area | Registered: Jan 2003
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92stangLX
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Member # 3252
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posted
You will probably need an 8 ohm sub for it to work correctly
Posts: 5302 | From: San Francisco | Registered: Sep 2003
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venomous99
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Member # 1917
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posted
you can also look at some dual voice coil subs where you'll have more wiring flexibility to alter the effective impedance. only thing is you may be underdriving the subs depending on what amp you have. majority of aftermarket amps on the market are 4ohms and is a good reason why you see lots of 4ohm subs.
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MKII Q7
89LX
Posts: 4811 | From: dc | Registered: Oct 2002
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asskickn88
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Member # 4957
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posted
You either need an 8 ohm sub or a 4 ohm dual voice coil that you can wire in series to make 8 ohms. By cutting your ohm load in half your allowing the amp to make more power but also causing it to overheat and shut down. I know others have posted correct advise, I'm just trying to throw out a simple explanation ![[Big Grin]](biggrin.gif)
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Three 540 Bimmers and a 5.0 Explorer.... got a Ford back in the stable!
It's time for the country to do what Obama's own father did.
Abandon him.
Posts: 6069 | From: Rocklin, Ca | Registered: Oct 2004
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Wildfire532FB
CAFords OG
Member # 1482
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posted
Ok. I don't think I explained it good. My explorer comes stock with a 6 in sub. The stock sub was blown so I replaced it not thinking about ohms. The stock sub was an 8ohm I installed a 4ohm. What can I do besides replacing the amp or new sub? And if nothing anyone know of a small 4ohm amp I can buy that will be an exact replacement of my stock one?
Posts: 17578 | From: 530 | Registered: Jun 2002
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Wildfire532FB
CAFords OG
Member # 1482
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posted
anyone know?
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./_ _ _ ___ __\
(]]]_ _ o _ _[[[)
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68 Fastback
84 CJ7
94 HMMWV
95 GT
03 F350
17 Fusion Hybrid
Posts: 17578 | From: 530 | Registered: Jun 2002
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Blind
2.3L
CAFords OG
Member # 3052
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posted
http://www.zeroimpedance.com/products.html
or, as asskicken88 said, you can get a DVC speaker and wire it in series to show the amp an 8ohm load
[ April 25, 2009, 12:55 AM: Message edited by: Blind ]
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89 LX Notchback ex 4cyl, 14psi
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Posts: 8521 | From: Fairfield | Registered: Jul 2003
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Wildfire532FB
CAFords OG
Member # 1482
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posted
quote:
Originally posted by Blind:
http://www.zeroimpedance.com/products.html
or, as asskicken88 said, you can get a DVC speaker and wire it in series to show the amp an 8ohm load
what the hell is that website?
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./_ _ _ ___ __\
(]]]_ _ o _ _[[[)
|\_o_ __ __o_/|
|__|..........|__|
68 Fastback
84 CJ7
94 HMMWV
95 GT
03 F350
17 Fusion Hybrid
Posts: 17578 | From: 530 | Registered: Jun 2002
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