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Discussion Starter #1
Hey guys.
I've got two 12" Rockford P2's in a slot ported enclosure. The subs put out 250rms. My amp only puts out 200rms (I'll double check when I go to my car). The subs are 2ohm and the amp is mono. Now, if I were to upgrade to something that put out say 500rms (2 channel) or 250rms (mono) would I notice a signifigant difference? What would you suggest in my situation?
I'm sorry if what I'm saying doesn't make sense I don't have much experience with car audio:sadwave:.

Thanks.
 

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I've got two 12" Rockford P2's in a slot ported enclosure.

The volume and port dimensions are important to figure out how the drivers will sound in any enclosure.



The subs put out 250rms.

I disagree. Drivers are rated for input in terms of power, output in terms of dB across a frequency range.



My amp only puts out 200rms (I'll double check when I go to my car). The subs are 2ohm and the amp is mono. Now, if I were to upgrade to something that put out say 500rms (2 channel) or 250rms (mono) would I notice a signifigant difference?

Nobody can give you a meaningful response without having modeled those drivers in that specific enclosure. There are freeware modeling applications available. These will allow you to figure out at what power/volume/frequency the drivers will bottom out, and what their output will be with a given power and enclosure volume at any given frequency.

Failing that, you'd have to find someone with a similar setup and listen. I'd recommend finding an audio forum with more info on driver modeling.
 

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SuperNova
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Its hard to say. As an ex audiophile with now permanent upper range hearing loss as per my last hearing test a year ago, I must say......"You'll shoot your eye out kid."

My opinion is sell the subs and buy a DP.

But to answer your question, not necessarily. You might just be wasting your money.
 

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Discussion Starter #4
Thanks for the response.
They recommend 1.85 cu. ft. from Rockfords website. My box is 1.9 cu. ft.
The subs are rated at 250rms and 500 max.

Should I look for an amp that better suits the subs (power wise)? What would you recommend to get the best output possible?

Thanks!
 

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No offense, but i don't think you know enough about stereo operation to do this task on your own. No one here can answer your questions because they don't really make sense.

Number 1, the subs don't "put of 250 rms". It means that they can be powered with 250 watts forever without blowing up. Thus, if you want to run both of them with potential for full power, you will need an amp that will supply 500watts rms in some 2 channel configuration.

Number 2, you need to know the impedence of the amplifier and sub woofer (ohms). You need to make sure that in the final configuration, the impedance of the amplifier matches that of the speakers, or one or the other will melt. Usually, the amplifier will give you options on how to set the stereo up, and will usually provide diagrams.

Number 3, I dont tend to like ported boxes, as they are very "boomy", and not as clear as a sealed box. However, you need to find the manufacturers website for the subs, and see what size of ported box they recommend for those subs.

Hope i helped at all. If you have any specific questions after this, i'll be glad to help you out.
 

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Thanks for the response.
They recommend 1.85 cu. ft. from Rockfords website. My box is 1.9 cu. ft.
The subs are rated at 250rms and 500 max.

Given the internal volume taken up by the sub baskets and any stuffing, you may be spot on regarding volume. However, you still need to figure out the optimal port size for tuning to a specific frequency response.

Should I look for an amp that better suits the subs (power wise)? What would you recommend to get the best output possible?
This can be answered one of four ways:

Yes/no by someone that does not understand loudspeakers -- meaningless.

Empirically, by trying out different amps and/or different enclosures -- could be fun, could also be expensive.

From examples, by someone with the same setup that's measured or modeled it -- now we're getting somewhere.

By modeling the enclosure, port, and drivers and seeing what response is available at what volumes, port sizes, and power levels -- winner.

The manufacturer would be able to recommend a port size and power level to adequately drive their woofers and provide you with rough frequency response and output curves given enough info about your situation. I don't know that they will, but they certainly can.
 

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Discussion Starter #9
No offense, but i don't think you know enough about stereo operation to do this task on your own. No one here can answer your questions because they don't really make sense.

Number 1, the subs don't "put of 250 rms". It means that they can be powered with 250 watts forever without blowing up. Thus, if you want to run both of them with potential for full power, you will need an amp that will supply 500watts rms in some 2 channel configuration.

Number 2, you need to know the impedence of the amplifier and sub woofer (ohms). You need to make sure that in the final configuration, the impedance of the amplifier matches that of the speakers, or one or the other will melt. Usually, the amplifier will give you options on how to set the stereo up, and will usually provide diagrams.

Number 3, I dont tend to like ported boxes, as they are very "boomy", and not as clear as a sealed box. However, you need to find the manufacturers website for the subs, and see what size of ported box they recommend for those subs.

Hope i helped at all. If you have any specific questions after this, i'll be glad to help you out.
Thanks. I realize the Sub does not "put out" 250 rms. My mistake, bad choice of words.

The subs are 2 ohm and the amp is 2 ohm.

I posted above the specs of my box and the recommended cu. ft. from Rockford Fosgate's website.
 

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Discussion Starter #10
Given the internal volume taken up by the sub baskets and any stuffing, you may be spot on regarding volume. However, you still need to figure out the optimal port size for tuning to a specific frequency response.



This can be answered one of four ways:

Yes/no by someone that does not understand loudspeakers -- meaningless.

Empirically, by trying out different amps and/or different enclosures -- could be fun, could also be expensive.

From examples, by someone with the same setup that's measured or modeled it -- now we're getting somewhere.

By modeling the enclosure, port, and drivers and seeing what response is available at what volumes, port sizes, and power levels -- winner.

The manufacturer would be able to recommend a port size and power level to adequately drive their woofers and provide you with rough frequency response and output curves given enough info about your situation. I don't know that they will, but they certainly can.
The recommended tuning frequency of the subs is 38hz. My box is tuned to 39hz (If that makes sense :rotfl:).

I'm just wandering what amp would best power my subs with my setup :p
 

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OK it seems you have a box of the correct volume with the correct tuning. At this point, if the amp can drive your speakers to adequate levels, you can call it a day.
 

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Discussion Starter #12
OK it seems you have a box of the correct volume with the correct tuning. At this point, if the amp can drive your speakers to adequate levels, you can call it a day.
That's good news!
So, would you get a mono amp at say 600 rms and wire paralell? Go with a 2-channel amp? What's the best route in your opinion?
 

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Discussion Starter #14

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I apologize, not too many of us on here are big audiophiles anymore. I have a lot of knowledge and know how (used to design and install systems) on the subject but no interest or patience for it now that I can't hear.

SD_GR is a very knowledgeable guy (I think he owns Wikipedia:)).

For the best advice on designing your system, a more helpful forum would undoubtedly be:

www.sounddomain.com
www.cardomain.com

They should be able to steer you in the right direction.

As a whole here we seem just to "Wanna go fast.":tongue:
 

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So a guy at a store recommended this amp:
http://www.rockfordfosgate.com/products/product_details.asp?cat_id=2&series_id=6&family_id=19&item_id=91949&locale=en_US
How would I wire this set-up to have 300 going to each sub? Positive from amp to positive on one sub, neg from sub to pos on other sub, then neg from last sub to neg on amp?
OK so this is going to get a little confusing, but i will try to keep this as clear as possible.

1. Keep ure current amp. Its 400W RMS vs that rockford that dude reccomended which is 300 RMS. Peak power means nothing, its all about the rms. Since neither amp is the 500W RMS u want, u may as well keep your current one.


2: Wiring the subs... here is where it will get confusing, luckily I was able to find a diagram for you. so its not gonna be that confusing after all.
http:://www.rockfordfosgate.com/rftech/woofer_wizard/2_2ohmDVC_2ohm.gif
 

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Are each of your subs 2 ohm rated?

Even though "stereo" isnt really recommended for subs, it could work fine with your stereo amp. Simply put one 2 ohm sub on each amp channel, this will gain you a lot of power over more common 4 ohm rated subs. I had a TRU Technology amp in which I ran two JL 10W3 that way.



http://74.220.202.31/~bellbott/sounds.html

I found your amp. It is a BAD match for two 2 ohm subs.

200 watts RMS x 1 at 4 ohms (400 watts RMS x 1 at 2 ohms)
To acheive the 400Wrms you want, you need to present the amp with a 2 ohm final load. You cannot do that with two 2 ohm subs. You either parallel them for a 1 ohm load, or you series them for a 4 ohm load. Neither one is the 2 ohm load you want. Swap your subs for two 4 ohm subs. Then parallel them down to 2 ohm. Then your amp works fine at 400Wrms. The amp is smarter to keep since its mono and already made for subs.
 

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Discussion Starter #20
Sorry guys, I made a huge mistake. Subs are SVC 4ohm rated at 200 rms. I had them wired in series.. producing an 8ohm load on the amp. I re-wired them parallel last night and they sound a lot better! Thanks for all the help though. I've read everyone's advice and links and got myself a basic knowledge of what to do so I don't get in a rut like this again :rotfl:.

Soon to come anyways, two 12" type-r's and a 1000 watt mono alpine amp. The P2's will do for now though :)

Thanks again!
 
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