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choosing amp and enclosure


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belcom 
Member - Posts: 20
Member spacespace
Joined: September 12, 2006
Location: Canada
Posted: September 12, 2006 at 10:02 PM / IP Logged  
I bought an Alpine Type R SWR-1021D sub. It is 300watts RMS dual 2ohm voice coil. I called Alpine today and they suggested I buy either a MRP-M450 or MRP-M650 amp for this sub.
Looking on this site at the sub wiring I understand that I can only wire it properly in series using both coils and making a 4ohm load. Otherwise I would need a 1 ohm stable amp. Before I saw the diagrams I thought I'd be running it at 2ohms and was looking at all the amps RMS power in 2 ohm setup. But now I realize I should've bought a 4ohm dual coil sub.
I just came across a local classified ad and can get a very good deal on an Alpine MRD-M300 amp which is 150 x 1 at 4ohm and 300 x 1 in 2 ohm.
Will this amp be sufficient for this sub? Or should I be looking for something else around 300w RMS at 4ohm ?
Also I was thinking of bulding a sealed sonotube enclosure for the sub. Is that a good idea? or would go with a regular box? I need something that will not take much space in the trunk. (2001 Acura CL)
Bmnicolosi 
Copper - Posts: 173
Copper spacespace
Joined: January 26, 2005
Location: Louisiana, United States
Posted: September 12, 2006 at 10:39 PM / IP Logged  
i wouldn't put that amp on it.  you'll blow it faster underpowering it than you will overpowering it--any chance of returning it for a dual 4?
If you say "I already know how", don't ask me a single question.
belcom 
Member - Posts: 20
Member spacespace
Joined: September 12, 2006
Location: Canada
Posted: September 12, 2006 at 10:46 PM / IP Logged  
nah, ebay deal. but it's new. so maybe I'll try to sell it locally. live and learn as they say... choosing amp and enclosure -- posted image.
belcom 
Member - Posts: 20
Member spacespace
Joined: September 12, 2006
Location: Canada
Posted: September 12, 2006 at 10:59 PM / IP Logged  
what about MRD-M500 which is 250w RMS at 4 ohm ?
aznboi3644 
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Joined: May 01, 2006
Location: United States
Posted: September 12, 2006 at 11:02 PM / IP Logged  
How about not looking at mono amps and find a good 2 channel amp that will put out around 250 watts per channel at 2 ohms??
kicker guy 
Copper - Posts: 86
Copper spacespace
Joined: August 25, 2006
Location: United States
Posted: September 12, 2006 at 11:22 PM / IP Logged  
Bmnicolosi wrote:
i wouldn't put that amp on it.  you'll blow it faster underpowering it than you will overpowering it--any chance of returning it for a dual 4?
You can't blow a sub by underpowering it... IF that was the case you could never turn down the volume
I would find a good 2 channel that u can bridge to 4 Ohm at 300 rms
stevdart 
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Platinum spaceThis member has made a donation to the12volt.com. Click here for more info.spaceThis member has been recognized as an authority in Mobile Audio and Video. Click here for more info.spaceThis member consistently provides reliable informationspace
Joined: January 24, 2004
Location: Pennsylvania, United States
Posted: September 13, 2006 at 5:26 AM / IP Logged  
djscustomz wrote:

are you serious..?   you can easily kill a subwoofer by under powering it... the sub will begin to through itself at high volumes instead of being a controlled vibration... it will ruin the voice coil.... you are a moron....   

I think this guy should have stayed away from this forum cause obviously he has his stuff installed by someone else and could do an install to save his life....

This type of comment is inappropriate for this forum.  I suggest you read the rules and follow the established guidelines set by the forum admin, mods and senior members.

Now, for the question at hand:  the OP is stuck with a sub that will run at 4 ohms instead of the 2 ohms he wanted to run it at.  That is not a big problem, and not even a problem at all when you look at these facts:

1.  300 watts is not hard to come by in the realm of car audio amplification, whether it's 300 watts at 4 ohms with a mono amp or a bridged two channel amp.

2.  You can use less power than 300 watts to that sub.  "Underpowering kills a sub" is a myth...proper setup and control of the volume knob are necessary with any system regardless of power.

3.  You do not have to match sub RMS to amplifier power output.

I suggest you use a class D mono amp that is rated at 200+ watts at 4 ohms.  You should find many that will output 250 watts at reasonable prices, and go 300 watts if you find one you like.  This will allow you the flexibility in the future to add another identical sub...at that time you can still use the same amp at 2 ohms. 

Build the box so that it performs well in the worst case scenario and, in return, it will reward you at all times.
belcom 
Member - Posts: 20
Member spacespace
Joined: September 12, 2006
Location: Canada
Posted: September 13, 2006 at 12:22 PM / IP Logged  
I am looking at 2 options right now for an amp...
Rockford Fosgate P6002 which is fairly new and it can supply 300w RMS x 2 at 2ohm or 600w rms x 1 (bridged) at 4ohm
or
Rockford Fosgate 500a2 (old school) which will give me 500w RMS x 1 at 4 ohm
I did a couple installs using some used old equipment before and it was all right but I never really got into specifics of the power and proper tuning. And THAT is why I am trying to get some advice from people on this forum.
Alpine tech actually did say that the subwoofer would be better off overpowered than under powered. He said because there would be not enough movement the coil could get damaged. He also mentioned that you need tremendous amount of power to blow that sub. So with that said I think I should be all right supplying either 300w RMS x 2 at 2ohm or 600w RMS x 1 (bridged) at 4ohm (in series).
cloak559 
Copper - Posts: 215
Copper spacespace
Joined: July 14, 2006
Location: United States
Posted: September 13, 2006 at 1:52 PM / IP Logged  
I would go with the 500a2. Its a good solid amp and it should be okay to run it to that sub, just make sure you keep your bass boost down and set your gains correctly...
'89 Mercedes-Benz 300E
Pioneer DEH-5900UB
(2)RE Audio SX 10"s
(1)US Amps MD3D
3ft^3 @ 37Hz
Blowing up in a car accident doesnt worry me, as long as I'm putting out some major dB's when I die...
belcom 
Member - Posts: 20
Member spacespace
Joined: September 12, 2006
Location: Canada
Posted: September 26, 2006 at 1:33 PM / IP Logged  
I need some professional input. I am now looking at Alpine MRV-T420 2 channel A/B type amp against MRP-M450 they're same price used. The T420 pushes 340w RMS x 1 into 4ohm or 170w RMS x 2 into 2ohm but M450 only 220w RMS x 1 into 4ohm. Also I was wondering about efficiency... I understand someone have mentioned before tha D-class amps are about 80% more efficient than A/B type. So would M450 be pushing the sub better with less power than the T420 with more power? Please help me understand this and choose the right one.
So which one of these would better suite my Alpine Type R (SWR-1021D) 300w RMS sub ?
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