how to pick a Amp help

[McBadass]

ok So I'm looking to go 3x Rockford Fosgate P3D410 800W Dual 4 ohm Sub-woofers. Would a mtx 2400w mono amp power all three of them?

 

[goldenboy88]

Dear god yes, over power is more like it. While Rockford is good in under rating their amps I don't know what their ratings are like on their subs. But those subs are rated for 400 rms not 800. 800 is what it will achieve a millisecond before it cooks itself. A 1500 rms amp would do the trick nicely. Also needing to be asked is will you be running them series, parallel or separate channels, because that will make a big difference on what you buy for an amp.

Edit: just noticed you said an mtx amp, now I ran an older mtx thunder for a couple years and while it never failed to thump nicely except when I had a ground issue, they do have a tendency to overheat and fry themselves.

 

[McBadass]

I have no clue how I would wire them except I have heard somewhere that series is maybe the way to go with 3 subs and 1 mono amp (or maybe it was parallel). I had 2 Rockford P1's before and they hit hard.... so im thinking 3 p3's will much better

 

[goldenboy88]

Look at the stickied Audio FAQ, 1sty explained it quite nicely and has diagrams.

Edit: I don't know where you're planning on buying from but onlinecarstereo.com has those p3's for $129 each and I found some Alpine type R's for $109-$125 which are pushing a bit more power rms. Haven't heard either but personally I'm looking at getting a 15" Type R and 2 10" Type X's when I get the money to start the system in my Protege and upgrading to Orion Hcca's later on. Rockford amps, if you afford them or get one for a good price, are kick ass amps though. Biggest system I've heard of ran Rockford amps and he's pushing 30,000 watts.

 

[Jalum]

The P3D410's are actually only 300rms. Just find a 1000watt mono amp because RF actually under rates everything. I'm pushing around 370watts in each of my P3D410's off my RF T600-2 and the amp is actually rated at just under 700. You can play it safe and find an 800 watt amp. As for wiring...here's how you should do it. Just pick the one that best suits the Ohm load.

8 Ohm speakers = 2 Ohm load
http://www.rockfordfosgate.com/rftech/woofer_wizard/4_8ohmSVC_2ohm.gif

4 Ohm speakers = 1 Ohm load
http://www.rockfordfosgate.com/rftech/woofer_wizard/4_4ohmSVC_1ohm.gif

2 Ohm speakers = 1 Ohm load
http://www.rockfordfosgate.com/rftech/woofer_wizard/4_2ohmDVC_1ohm.gif

I hope this helps. For your wiring question to a mono amp.

 

[McBadass]

so lets say for wiring 2 x 75w rms 4 ohm speakers. would 70w rms at 4 ohms work or should I match it with 75w or greater? this whole picking the right amp thing is confusing to me especially when every company rates their amps differently (Sony is a great example of this)

 

[Jalum]

You never want to overpower your speakers or subs, but you never want to under power them either. It's best to under power so you don't blow them, though. 70w rms would have no problem at 4 Ohms if that speaker is rated for that.

 

[McBadass]

so I found a boston acoustics amp at 80wx2 4ohm that is the closest amp from boston acoustic to power the boston acoustic speakers that are 75rms 4ohm... I would still want to go with the MTX 702x that does 70w x2 4 ohm?

 

[denim]

There is no such thing as under powering speakers. A speaker will play music or tones at 1 watt or 10000 watts. Also, people need to stop worrying about matching the rms of the sub to the wattage ratting of the amplifier. Music is dynamic and rarely is the speaker going to actually see the rms ratted power. I hope people are not looking at "peak" power as that is just marketing garbage.

The RF P3's are ok, but I feel with a little research you can find better performing drivers for the same money.

 

[McBadass]

ya im not getting subs again until I find some more money. right now its upgrading to component speakers. idk tho I did find 3 P3's for $330 and box for $70ish... decent deal I thought.

 

[719prottege]

AN amp

 

[ScratchNSniff]

If you need a 4 Channel amp, or two let me know...I have quite a bit of car audio for sale right now...

One Infinity 4 Channel and one Rockford T400-4...

 

[McBadass]

You have a T-4.... hm... ok ill pm but you really only have 10h to let me know before the action on ebay is over for the boston acoustic amp. pm sent

 

[Jalum]

There is no such thing as under powering speakers. A speaker will play music or tones at 1 watt or 10000 watts. Also, people need to stop worrying about matching the rms of the sub to the wattage ratting of the amplifier. Music is dynamic and rarely is the speaker going to actually see the rms ratted power. I hope people are not looking at "peak" power as that is just marketing garbage.

The RF P3's are ok, but I feel with a little research you can find better performing drivers for the same money.

You can very well under power a speaker. I've got 2 400watt rms Audiobahns connected to my computer that used to be in my car. They were originally connected to a 800watt amp and they sounded great. I took them out and put a 200watt amp on them and they barely rattle the apartment.

Anything that has electricity running through it works like a light bulb. If you have a 60watt bulb and put 60 watts through it, it'll be as bright as it should be. If you put 20watts through it then it won't be as bright. I'm an electrician and I know that you can under power anything if done wrong (or right). But you are right. The speaker will still produce sound/bass regardless. It's just not as much.

That's just my 2 cents on that.

 

[denim]

You can very well under power a speaker. I've got 2 400watt rms Audiobahns connected to my computer that used to be in my car. They were originally connected to a 800watt amp and they sounded great. I took them out and put a 200watt amp on them and they barely rattle the apartment.

Anything that has electricity running through it works like a light bulb. If you have a 60watt bulb and put 60 watts through it, it'll be as bright as it should be. If you put 20watts through it then it won't be as bright. I'm an electrician and I know that you can under power anything if done wrong (or right). But you are right. The speaker will still produce sound/bass regardless. It's just not as much.

That's just my 2 cents on that.

The reason I mention it, is due to the issue being a negative connotation with the wording "under powering". I am well aware on power applied directly effects the output produced. The point I was trying to explain was that there is no problem to send less then ratted, and that "under powering" does not really exist, more so that there is powering a speaker and over powering a speaker. The difference is one should cause no damage or strain to the speaker, the other is pushing past the intended design limits.

The context is dealing with the car audio industry and the customer base, many of whom wrongly believe that sending less power then what a speaker is ratted for can blow the speaker. When in reality it is not the speaker that failed, but the person behind the gain knob or volume.

If there was a way to remove it from the industry vocabulary, along with "Peak Power", things would be much better.

 

[McBadass]

well im not sure what 12.4v or 14.4v im powering the amp I got. but at 14.4v its 80w rms x2 4 ohm to power 75w rms x 2 at 4ohm speakers.... so i think ill be fine? right?

 

[denim]

Yes, just set your gains so you are not clipping.

 

[McBadass]

cool I thought so but am kinda confused haha. thanks for the help

 

[denim]

cool I thought so but am kinda confused haha. thanks for the help

If you have a DMM or O'scope it will help. But with some practice, you can set by ear carefully.

 

[McBadass]

ya I had a mono for my subs that I could tune by ear... but that was really just bass gains and not all the levels together. I have an old friend that helped install my old stuff so I could always hit him up for help haha