Single Amp for all?

Hi everyone,
I'm new to this forum, and I have a question for anyone that might oblige.
It has been recommended that I use an RF amp to power my whole system, due to space constraints and preference to keep the vehicle in [close to]factory condition. I am no pro but this struck me as a bit strange because i had never heard of this before.
my equipment:
Polk db 6.5" component system
Polk db 6.75" coaxial
Alpine 9847 deck
MB Quart Premium 12" 500w@4 Ohms

to be run with a
RF amp [i can't remember the model] 800watts x 2 channel

anybody know what this bloke is on about?

thanks

i know rockford makes a 5 channel amp maybe this would be better suited.

Unless your installer is recomending using head unit power for your main speakers and an amp for subwoofers.

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A single 5 channel amp might do the trick if you get one with sufficient power output to the 5th sub channel, but most of us would use a 4 channel and a mono amp.  Is it possible that you told this (salesman?) that you were on a limited budget and had no room?  Perhaps he was thinking of powering the speakers with the head unit?  Who knows?  And "factory condition" can always be reverted back to, in the end.  Get your system the way you want it...it's your car.

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Build the box so that it performs well in the worst case scenario and, in return, it will reward you at all times.

Thanks guys for replying. Installer was serious about configuring a 2 channel amp to power the whole system.

stevdart - Yes I told him I am on a budget, he checked my space and said that he could power it all on one amp and it is my preference to stay close to factory btw. I drive an 2005 Volkswagen GTI and the front seats have a large housing for the mechanism that raises the seat for rear seat access. so no amp will fit that I have seen. I think he wanted to do passive crossovers and maximize power to the sub.(?) Any idea about what this will sound like?

Otherwise i would install the Quart amp I bought for the sub, the sticking point being the lack of space for a component amp, with just the quart amp/sub I already have 1/2 the trunk space.

this has me a bit nervous i must say.

cold]T wrote:

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anks guys for replying. Installer was serious about configuring a 2 channel amp to power the whole system. .

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That is a bad idea.  Ask him how he plans to cross over the subwoofers.

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DYohn, I think I mentioned in my original post, there's only one sub, a Quart 12" if that effects your opinion at all. The RF amp has a built in sub crossover with a remote.
I agree that this is proably not the greatest idea. I am trying to make it work with the space I have, you know?

The Alpine 9847 has a pretty good built-in amplifier.  If you have to stick with the gear you list, I'd power the Polk's off the head unit and use the amp only for the sub.  Trying to do anyting else is really asking for trouble, as long as you cannot go for a 5- or 6-channel amp as suggested earlier.

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Thanks DYohn, I considered going head unit to the cabin and amp to the sub. I don't have to stick with the gear I have though, so I am open to suggestions. all my stuff is still under the 30 day return policy.

OK, you say you chose the RF amp because of size limitations.  What's the model number of that amp?  How much space do you have available? 

By the way, if the crossover built into the amp is activated as a low-pass for the sub-woofer, it is no longer possible to drive full-range speakers with it.  I suspect you may have the installer's intent wrong.  No pro would suggest powering mains and subs off the same amp unless using an external tri-power crossover, and then only as a last resort.

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DYohn, it was the installer who suggested the amp, with much confidence even. I looked at the specs and said 'this is a two channel amp though.' and he was like 'yup'. And he explained the way he would do it, it was most likely the kind of crossover you mentioned above. I really think he wants to do one channel to the sub and the other channel to all the rest!!!
        BTW the RF model is 3002 150x2 at 1ohm.
I think I will go elsewhere for the install, and probably end up going head unit to components and rear coaxial speakers, then just powering up the 12" with the quart amp I already have! Or else I could just keep the fac sys and use crossovers on the fac speakers, add the sub and amp which has individual gain and crossover.
at any rate, thanks everyone who offered advice, especially DYohn, I am learning alot and with any luck my ride should be bumpin by the weekend!
Later

Yes the amp is the new power series 3002 Rockford Fosgate amp... I'm sure he just came back from an RTTI training where ron trout showed him how to hook up 20 P1 12" woofers and 2 PR. of 3 way 6x9's so do the math thats 32 speakers off 1 300 WATT AMP!!!!!!! This lil amp is awesome! I did a similar amp install in a boat...

Since its a 2 channel amp you will loose your front rear fader but many people do not care about this feature anyways... He will run both left speakers to the left channel and both right speakers to the right challed capped off with (DON'T QUOTE ME like 200hz caps) I'd have to check at the shop to be positive there from the install edge... then bridge the sub as normal left+ and right- and use one of those big ol' coils inside the box to cross over at like 80hz and down...

At the RTTI they had this set up playing some loud music not just like classical with a few bass notes here and there but some serious rock and techno and the amp loved it... Never shut down with 32 speakers drawing off it... It sounded like a concert (almost) with 20 12" woofers paired in ported enclosures. Rockford dealers could purchasse this set up to display in their shops and show off... Trust me when you show a kid what an amp that sells for (DON'T QUOTE ME AGAIN I ONLY INSTALL SO MY PRICES MIGHT BE OFF? $399.95) can do 99 times out of 100 the kid is sold on the amp... its just the awe factor...

He's not lying to you and it can be done with confidence and a fairly low budget... But you can get a 5 channel amp or whatever you want? All i'm saying is that i've seen it done and you won't be dissappointed

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Of course it can be done.  Any amp can power any number of speakers as long as the impedance loading is correct.  Just look at line arrays.  I was only saying it is a STUPID idea IMO to do this specific install, especially when you toss a sub-woofer into the mix, and to expect anything approaching good sound quality in the vehicle.  There are far, far better ways to accomplish a good install in a car.

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oh most definately! I just misunderstood and thought that u guys thought it COULDN'T be done I was just here to back up what the installer told cold... sorry for the mixup i'll shut up now

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That's cool, BoominRolla, it's good to hear what's going on in the industry.

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Build the box so that it performs well in the worst case scenario and, in return, it will reward you at all times.

BoominRolla, that is exactly what the installer told me; the story about the 'wall of speakers' demonstration. It sounded overblown, and far too specific for my needs. It could be done ,yes, but you lose fade and the ability to adjust the sections of the system separately. The system could therefore be called 'all crossover' as that is where much of the adjustments are coming from. The 32 12"s idea is just a demonstration of what can be done, to show the amps true character. In real life, not flexible enough.
The installer was trying to save me trunk space, and I think he just had a hard-on for the RF3002 and he just wanted to show off this impressive bit of technical data.

A quick update, I went down to the shop this afternoon and had a long chat with another bloke that works with the installer who originally recomended the RF idea[who had left for the day]. He also brought up the now infamous Ron Trout training session, which these guys must use on alot of customers. So in the end I decided to go up to a 5 channel Eclipse amp(100x4, 500x1) to run the whole lot, so I can have more control over the gain of each section and it's actually a little smaller than the Quart amp I bought to match the sub so it does save space. the Eclipse RMS power output is only slighty lower in the sub section than the Quart, the other power matches my components and rear speakers perfectly.

Big up BoominRolla - don't shut up, you represented on that one!!!