How much Power do I need?

[Cincinnati Scott]

Gang,
I'm going to be powering 2 Infinity 6.5 3-ways and my SOS sub box with a 10" Earthquake SWS Sub.

I was looking at two different Alpine 4-ways. One that is 40 Watts, the other that is 70 watts. The sub power would be from pairs 3 and 4 bridged. With the one it is 100 RMS bridged, and the other is 200 RMS bridged.

I would think either would work, but wondered what conventional wisdom is.

Thanks in advance!

 

[Hugh]

Go with the more powerful amp, especially with a 10" sub. More power is always better. Speakers are more often damaged by underpowered amps that are clipping than by amps that have more power than a speaker's rating.

Now I have a craving for some Skyline Chili. There happens to be one in Fort lauderdale. Give me large 3 way!

 

[D'Ecosse]

I apologize in advance - I'm going to give commentary that wasn't requested, but given with best intentions! <!--StartFragment -->

Something to consider from this independent test that Earthquake actually uses in their promotional literature:

DUMAX measurements show that the Earthquake SWS-10 10-incher is a high-Q subwoofer best suited for use in sealed enclosures (which I prefer). Both DUMAX testing and computer modeling show that — although the SWS-10 doesn't require much rear clearance — its compliant suspension means a Vas of nearly 3.5 cubic feet. This, in turn, means that the sub will need a sealed enclosure of 1.0 cubic foot or greater (1.75 cubic feet internal volume seems to be optimal) for the best in-vehicle response. This is larger than the enclosure needed by a typical 10 (0.6 to 0.75 cubic foot).

i.e. Although it has a small physical size (small depth requirement), that does not transpond in this case to a small enclosure, so be careful not to align the two paramters. Now I haven't heard this component & am only quoting here - I know Malibu Rapper has good things to say about it though.

For your question - also from same report Tom says that he can smell the glue melting at the rated 200W - however I'd rather personally have the overhead capability, but please see note below regarding the specs for bridged.

Are you reading the specs correctly on the amps?

Looking at the V-Series amps -
The MRP-F450 is 70W per and 350 bridged
The MRP-F250 is 40W per & 180 bridged

<s>The only 3-ways I'm aware from Alpine are the co-ax 6 x 9's @40W - the SPS series - are those the ones?</s>
edit - just noticed you said Infinity 3-way - let me check on those!

I think the MRP-F250 should probably be plenty.

Respectfully, I think you can make better choices especially for your door speakers but also the sub.
For the door speakers, if you stretch just a little towards or just over the $200 mark you can probably get some decent compnents in a co-axial mounted fitment.

If you are using one of the current sub boxes available, they will take a deeper speaker anyway and you have a decent set of choices.
If you're making your own box from scratch & want to go shallow, consider an 8" square Kicker Isobaric, which has virtually the surface area of a 10 anyway.

Are these the door speakers you selected?- The larger amp (70W) would probably be better for those at 75W RMS rating

 

[Cincinnati Scott]

I apologize in advance - I'm going to give commentary that wasn't requested, but given with best intentions! <!--StartFragment -->

Something to consider from this independent test that Earthquake actually uses in their promotional literature:



i.e. Although it has a small physical size (small depth requirement), that does not transpond in this case to a small enclosure, so be careful not to align the two paramters. Now I haven't heard this component & am only quoting here - I know Malibu Rapper has good things to say about it though.

For your question - also from same report Tom says that he can smell the glue melting at the rated 200W - however I'd rather personally have the overhead capability, but [please see not ebelow regarding the specs for bridged.

Are you reading the specs correctly on the amps?

Looking at the V-Series amps -
The MRP-F450 is 70W per and 350 bridged
The MRP-F250 is 40W per & 180 bridged

The only 3-ways I'm aware from Alpine are the co-ax 6 x 9's @40W - the SPS series - are those the ones?

I think the MRP-F250 should probably be plenty.

Respectfully, I think you can make better choices especially for your door speakers but also the sub.
If you are using one of the current sub boxes available, they will take a deeper speaker and you have a decent set of choices.
If you're making your own box & want to go shallow, consider an 8" square Kicker Isobaric, which has virtually the surface area of a 10 anyway.

Well, I certainly respect your opinion, D', but for now, I'm re-using what was in the car when I bought it. The installation wiring was a total disaster, so I'm re-doing that and moving the amp install to the trunk. The previous owner had a Sony Xplod Amp velcro'd behind the driver's seat that I could not look at anymore!

I don't like much about the system as it sits, but until my wife is finished being Mrs Rockefeller at our new house, I'll be stuck with what I've got.

I think I'll like the new amp that I'm sneaking in the door though :biggrin:
Will the F250 give me enough juice if I upgrade to something else later?

 

[D'Ecosse]

I think I'll like the new amp that I'm sneaking in the door though :biggrin:
Will the F250 give me enough juice if I upgrade to something else later?

I hear you!!!!!!

I didn't immediately realize you already had these pieces (& also failed to notice you mentioned you would be using the SOS box)

Probably go with the 450 I think .... that actually will be a reasonable amp for the current speakers & even for upgrade of the components & sub later. Just don't push that sub too hard with it!

 

[D'Ecosse]

From one Scott to another ........

LOL! Just realized - More Power, Scotty! (enunciated with rolling 'R's)

(Not only is my surname Scott but I am actually the 'real' thing too - D'Ecosse actually means 'from Scotland)