Question about Ohm in subs - Page 2 - GM Forum - Buick, Cadillac, Chev, Olds, GMC & Pontiac chat


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Old 07-11-2007, 10:22 PM   #11
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Whats your thoughts on this amp guys?

http://cgi.ebay.ca/ROCKFORD-FOSGATE-...QQcmdZViewItem

I want to get my amp off of ebay.
I've heard alot of good things about rockford fosgate.
It says 2 Ohms: 275 watts RMS x 2 chan. Would it be alright to wire these subs and run them at 2 ohms?

Also it says 4-gauge power and ground leads, So I'm guessing I need a 4-guage wiring kit?

If so, is this one good?

http://cgi.ebay.ca/NEW-PHOENIX-GOLD-...QQcmdZViewItem

Thanks guys,

Mick
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Old 07-12-2007, 01:33 AM   #12
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It doesn't matter if the amp you buy is a 2 channel or 1 channel (Mono Block) as long as you match it properly with the Box that you buy.

The easiest way I can explain the restance (Ohms) when it comes to wiring the subs to the amp, is;
"Think of the amplifer as having a set of eyes looking out". What ever resistance you show the amp is the determining factor for how much power its going to produce.

The lower the resistance the more power the amp will produce but only down to a set resistance determinded by the manufacturer. If you drop the resistance lower than the amp can handle, it will overheat.
The resistance you show the amp is determined by how you wire the speakers and how many speakers you connect.

For the speakers you have purchased:

You need either, a 2 channel amp that is 2 Ohm stable and a Sub box with 2 seperate connections on it (one for each sub).

OR

You need a Mono Block amp that is 1 Ohm stable

Mono block amps (Class D) are more efficent than class A/B amps (like 2 and 4 channel amps).
In other words when the Bass starts hitting hard a "class D" doesn't kill your electrical system because its not wasting power and transfering it to heat.
Its more efficent at using the power its drawing, no waste.

Best advice I can give you since your not buying your Amp and Box from a store is buy the Amp first and post which one you bought. Then we will try and help you match up a box with it.

As far as the amp goes, that will work. Fosgate is always a safe bet there stuff is bullet proof.

I didn't check out either of your links but any 4 guage wiring kit will do. The Phenoix Gold is a good choice.

Hope this helped,
Dutch
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Old 07-13-2007, 01:56 AM   #13
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(not trying to flame you dutch, just clarifying )


Quote:
Originally Posted by Dutch2005
It doesn't matter if the amp you buy is a 2 channel or 1 channel (Mono Block) as long as you match it properly with the Box that you buy
The amp needs to be matched to the subs, not the box. Then you buy or build a box that matches the manufacturers specs on tuning and cubic feet. ( doesn't need to be perfect )

Quote:
Originally Posted by Dutch2005
The lower the resistance the more power the amp will produce but only down to a set resistance determinded by the manufacturer. If you drop the resistance lower than the amp can handle, it will overheat
Not only will they overheat, but they will burn up, making them nothing more then an expensive paperweight. That is why it is critical to NOT have an ohm load any lower then the manufacturer suggests.


The reality about the box situation is that any box with two holes for 12" subs will work, but you should look for one with close to the suggested cubic feet for the subs. I have yet to see a store bought subwoofer box that does not have a wire terminal for each speaker, but if you find a box with only one, you can add another terminal cheap if that is the box you want.

You should get a box that has a center baffle as well, this way each half of the box acts like a seperate box.

as far as ported or sealed goes, that is up to you and what kind of music you listen to....
Ported boxes will give you more of the low frequency droan type bass. great for music with HEAVY LOUD bass. I like these boxes for Hip-Hop / Rap type music. they will work for other music as well though.

Sealed boxes will give you a tighter more punchy bass, better suited to rock type music where the bass is usually fast. These will also give you some low end booming bass, but not as much as the slotted boxes.

If you like to listen to ALL different kinds of music, you will probably be happiest using a sealed box, and I would actually recommend a sealed box for those subs anyways.
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Old 07-13-2007, 08:50 AM   #14
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Buy your amp install kit from here
http://www.knukonceptz.com/productMa...llation%20Kits

Its cheaper and better quality.

By the time you add shipping to the one on ebay you will spend almost 70 bucks on it. In which case you probably could have bought it locally for cheaper.
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Old 07-13-2007, 10:36 AM   #15
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Mick best buy has the Stinger set includes everything you need and they also have one with a cap depending on power you are pushing...
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Old 07-13-2007, 11:13 AM   #16
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I agree with the suggestions you guys mentioned.

I want to clairify something Crash93.........
The reason I said match the box to the Amp is this, Mick has two DVC subs.

One DVC sub wired in parallel will show 2 Ohms.

If you wire both subs in parallel and stick them in a box with only 1 set of terminal connections, you will have just paralleled the pair which means 1 Ohm or less at the terminal.

I was trying to save him from having to cut a hole for a second set of terminals.

Like I suggested in my previous post.............

Quote:
For the speakers you have purchased:

You need either, a 2 channel amp that is 2 Ohm stable and a Sub box with 2 seperate connections on it (one for each sub).

OR

You need a Mono Block amp that is 1 Ohm stable

The way that new Mono amps are built today you will still probably need a box that has 2 sets of terminals.
A few years back amp manufacturers only provided one set of connections (1 channel) for there mono amps.
Currently most are providing 2 connections (like a 2 channel) which are paralleled inside the amp.

Dutch
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Old 07-13-2007, 04:00 PM   #17
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In regards to a mono amp.. and still staying with Rockford ... I'm guessing this is a good choice..?



http://cgi.ebay.ca/new-ROCKFORD-FOSG...ayphotohosting

"mono subwoofer amplifier
300 watts RMS x 1 at 4 ohms (600 watts RMS x 1 at 2 ohms) "

Thanks for the suggestion for the wiring kit Corvettecrazy.

As for the box, I plan on building a sealed box with my dad.
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Old 07-14-2007, 01:28 AM   #18
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That amp is last years model (06) I like the way they look compared to this years which are much smaller, but I have some concerns so I would not buy it just yet.

On this amp like most newer Mono amps there are 2 terminals that are wired in parallel on the inside of the amp.

In the manuals I was able to find on Fosgates website it shows that the minimum load you can show the amp is 4 Ohms per terminal. If this is correct, with your subs you would not be able to get max power out of the amp or you run the risk of overloading the amp.

I find this kind of odd because I own a 1001BD (model above) and it and the 3001 (model below) are 1 Ohm stable (which is what you need), but it says that the 6001 is not. This could be a mis-print in the manual for the 6001.

The 2 channel may be a better fit for your subs but let me try and find some more info at work tomorrow and I post what I find.

Dutch
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Old 07-14-2007, 02:43 AM   #19
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I am %100 with Dutch on this one. If that is not a misprint, then that is not the amp for you. You would be better off with the two channel amp that is stable at two ohms per channel.

I have a Viper d600.1 amp made by Directed Electronics inc. That amp would be perfect for your application, 600 watts X 1 RMS at 1 ohm. ( this amp also has two sets of outputs paralelled internallly ) That is perfect for two dual four ohm voice coil subs. I have been looking everywhere for one, but I can't seem to dig one up for you


If you want a mono amp, you need one that is 1 ohm stable.
If you want a stereo amp, you need one that is 2 ohm stereo stable.

trying to run an amp at less then the rated ohm load will burn it up
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Old 07-14-2007, 07:39 PM   #20
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I didn't get a chance to pull one of those amps from stock today, to check the manual.
To many installs.

From everything I have read online about that amp it is not 1 Ohm stable.

I would say return your subs and get different ones but I know that you got a good deal on them so I wouldn't recommend that.

You need a different amp, either the first 2 channel amp that you were thinking about or a Mono amp that is stable at 1 Ohm.

I will try and make time to pull one out of inventory tomorrow and check the manual to be 100% sure.

Dutch
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