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Discussion Starter #1
Im still looking at amps... and i look at the 2 channel ones and they all say (4 ohm stable in bridged mode)

does this mean I cannot bridge with those amps with my 2 ohm subwoofer?

I wanna install it today or tommorrow~~~


this is the amp i really want:
http://www.crutchfield.com/S-leqYw9R2huw/cgi-bin/ProdView.asp?g=120&I=158XM2002

I can grab one at my local PX for like 179. + tax free.

» 500 watts RMS x 1 at 4 ohms (4-ohm stable in bridged mode)

Mines 2ohm~~ Please help. by the way, my sub is 50-400wrms.
 

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Discussion Starter #3
okay im a noob. ill try to answer myself.

ohm = resistance, so 4ohm = more resistance than 2ohm. right so far?

so... if that amp can do 500wrms in 4ohm bridged......
it should do more wrms in 2ohm bridged.

and it should be possible, because ohm is just resistance and not a computer chip or anything physically hindering plugs.

so, i install the amp to my sub in bridged mode (+ from left side to + on sub, and - on right side to - on sub) and keep my gains low because ill be pushing quite a bit more than 500wrms to my subwoofer which can only handle 400wrms, ill be safe looks like.

(was reading some of Operator's sticky)
 

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All amplifiers are optimized to make maximum power into a certain load (in ohms). Some might be stable into a lower impedance load, but they may or may not generate more power into that load. Some older Rockford Fosgate amps were actually stable into a 2 ohm mono load, but they actually generated less power into a 2 ohm mono load than what they did into a 4 ohm mono load. If an amp is not stable into a certain load and you try to run it like that, your asking for trouble. Typically, you'll take out the power supply of the amp, but sometimes the outputs will also go into thermal runaway. Either condition will fry your amp.


It appears that they amplifier you linked to would more than likely become a nice looking paperweight if you attempt to run your sub off it.


If you're going to look at Crutchfield for your purchase, look at the mono sub amps. Just make sure it's rated to handle a 2 ohm load- http://www.crutchfield.com/S-e7Bsm6TGZrZ/cgi-bin/ProdGroup.asp?g=120&avf=N&nvpair=AG%5FNumber%5Fof%5FChannels%7CFFMono%5FSubwoofer

This would be a decent amp to run your sub- http://www.crutchfield.com/S-e7Bsm6TGZrZ/cgi-bin/ProdView.asp?g=120&I=489AP1000M
 

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Bridging can done many different ways. The important thing is that the amplifier has enough impedance to be stable.

Parallel loads:
Load Impedance = 1
1/Load1 + 1/Load2 + ...
Series Loads:
Load Impedance = Load1 + Load2 + ....


Bridging load = Total Load / number of bridges (usually=2)

Example: You have two four ohm loads, and if you run them in parallel, you get a 2-ohm total load.
The bridging load in this case would be: 2 ohms total load / 2 bridges = 1 ohm

A very few (very pricey) amps can handle 1 ohm loads. Most auto amplifiers are designed for 2-4 ohm impedance. So it would be dumb in this situation to run the two subs in parallel / bridged with most affordable amps. It would make more sense in this example to connect each voice coil to a separate amp channel without bridging them, giving a 4 ohm load per channel.

There are too many permuations of amps bridges, and loads to cover them all. But in general if you use the three equations above, you can find an arrangement that gives you 2-4 ohms load per amp channel, you will have a good setup.

The other rule of thumb is to keep it simple. I would prefer NOT to bridge amps if you don't need to, but on the other hand 2-ohm loads usually give you a free 20% or so more amplifier wattage over 4-ohm loads. Eight ohm reduce the amplifier wattage of most car amplifiers by 30% or more.
 

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[quote author=geewhizbang link=topic=68709.msg1188348#msg1188348 date=1170715756]
Bridging can done many different ways. The important thing is that the amplifier has enough impedance to be stable.

Parallel loads:
Load Impedance = 1
1/Load1 + 1/Load2 + ...
Series Loads:
Load Impedance = Load1 + Load2 + ....


Bridging load = Total Load / number of bridges (usually=2)

Example: You have two four ohm loads, and if you run them in parallel, you get a 2-ohm total load.
The bridging load in this case would be: 2 ohms total load / 2 bridges = 1 ohm

A very few (very pricey) amps can handle 1 ohm loads. Most auto amplifiers are designed for 2-4 ohm impedance. So it would be dumb in this situation to run the two subs in parallel / bridged with most affordable amps. It would make more sense in this example to connect each voice coil to a separate amp channel without bridging them, giving a 4 ohm load per channel.

There are too many permuations of amps bridges, and loads to cover them all. But in general if you use the three equations above, you can find an arrangement that gives you 2-4 ohms load per amp channel, you will have a good setup.

The other rule of thumb is to keep it simple. I would prefer NOT to bridge amps if you don't need to, but on the other hand 2-ohm loads usually give you a free 20% or so more amplifier wattage over 4-ohm loads. Eight ohm reduce the amplifier wattage of most car amplifiers by 30% or more.


[/quote]


Many car audio amplifiers will give you nearly double the output into a 2 ohm stereo load vs. a 4 ohm stereo load.


The popularity of dual voice coil subs and lower impedance (2 ohm, especially) subs are what have spurred the increased popularity of mono sub amps. Most of these are optimized to run a 2 or 1 ohm mono load.


The amp I linked above will handle a 2 ohm mono load and provide plenty of power (500 watts).
 

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is your sub a single voice coil?
 

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Discussion Starter #8

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[quote author=kspec link=topic=68709.msg1189005#msg1189005 date=1170733510]
http://www.crutchfield.com/S-WVs9vGezcyG/cgi-bin/ProdView.asp?g=510&I=206TCVT102

is what I bought.


That profile amp is neat, but i need something that looks attractive as well. That amp (no offense) is kinda ugly. I like how the sony 2002GTR looked. Crutchfield recommended me this:
http://www.crutchfield.com/S-WVs9vGezcyG/cgi-bin/ProdView.asp?g=120&I=500MRPM450

Alpine M450. I like it, but its about 200 bucks... :( Guess i can get it. But i dont want to order off the internet too much.
[/quote]

The Alpine will work just fine. Just get a mono amp that has ~500 watts at 2 ohms. Then you can get whatever amp you like the looks of best.


Crutchfield isn't that bad of a place. Not the cheapest prices, but at least they're authorized dealers for the products they sell, and you know you're not getting any knockoffs or serial numbers that have been cut out or scratched off. I purchased my Alpine PDX 4.150 amp form Crutchfield because my three local Alpine dealers all suck.
 

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Discussion Starter #10
cool cool. since it said 400wrms, i dont wanna be stuck keeping my gains up all the time, shortening the life of the amp. Pheonix told me to get something a little higher and keep my gains a little lower. which makes sense to me and what i really wanted to do. So i was really hoping i could get the Sony 2002GTR which said 4ohm stability when bridging... :( now i want my sub to be 4ohm lol. But mines 2ohm.

So you guys are positive with my subwoofer, i cant get the 2002GTR?
http://www.crutchfield.com/S-5vFbIs7FRNn/cgi-bin/ProdView.asp?g=120&I=158XM2002
 

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Since you already bought a sub, and it has a 2ohm rating, you will need to get an amplifier that can handle at least a 2 ohm load. When dealing with resistance, the lower the number the less resistance. Less resistance means more draw from the amplifier. 0 ohm is a direct short. No resistance.

You will find the less resistance the amp can handle, the more expensive it will be. There are numerous <= 2 ohm amplifiers that can be had for less than the Alpine linked above. But remember you get what you pay for.
 

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[quote author=kspec link=topic=68709.msg1189045#msg1189045 date=1170734191]
cool cool. since it said 400wrms, i dont wanna be stuck keeping my gains up all the time, shortening the life of the amp. Pheonix told me to get something a little higher and keep my gains a little lower. which makes sense to me and what i really wanted to do. So i was really hoping i could get the Sony 2002GTR which said 4ohm stability when bridging... :( now i want my sub to be 4ohm lol. But mines 2ohm.

So you guys are positive with my subwoofer, i cant get the 2002GTR?
http://www.crutchfield.com/S-5vFbIs7FRNn/cgi-bin/ProdView.asp?g=120&I=158XM2002
[/quote]

It clearly states on the Crutchfield site what the minimum impedance when bridged http://www.crutchfield.com/S-G5Z5DiEmks8/cgi-bin/ProdView.asp?g=120&tab=features_and_specs&i=158XM2002#Tab
Minimum Impedance Bridged 4
Like I said previously, if your sub is a 2 ohm sub, that Sony amp will become a pretty looking paperweight. Look at the mono amps, any of which are 2 ohm stable and produce ~500 watts at 2 ohms.
 

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you can get the alpine 450, that you posted earlier, on ebay for about $140 shipped. it will be more than enough for your speaker.
 

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Discussion Starter #14
i dont think ill ever ebay again after my cell phone incident.

best buy has the alpine for 203 dollars. + tax might bring it to like 230 or so...

230 for the alpine from a store should be decent. Im not into shipping things back if they mess up either, and maybe best buy can refund my money, etc.

but okay, dehoff, i think it was looking at the ohms in the wrong direction or something. thinking 2 ohm was better than 4, and if something can use 4, than 2 would be better. or something. i didnt fully understand it. but now i see it. Thanks! :)

Gonna get that alpine tommorrow. 45min drive to store~~ but should be worth it, i wanna install it tommorrow. maybe.
 

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lol!! where the f*** do you live? the nearest best buy is 45 min away? i have 3 within 15min.
 

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The Alpine amp does look very classy. I still think the Profile looks just fine though, with its no-frills functional appearance, much better than the usual ugly boy-racer styling of most aftermarket car audio.
 

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[quote author=kspec link=topic=68709.msg1189167#msg1189167 date=1170736650]
lawton oklahoma. lol....

we got two walmarts tho.
[/quote]

You go to OKC or Wichita Falls?
 

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Discussion Starter #19
i went to witchita falls yesterday.
went to the best buy and got myself the Alpine M450.

my system is installed! Thanks to everyone! I like it!! :D :D The Kicker CompVT pounds good and the amp is really nice too!!
 
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