If a subwoofer is rated at 125 watts RMS and I have 2 of them wired in parallel, does that mean that I need an amp that puts out about 250 watts or do I need an amp that puts out about 125 watts?
Also, anyone have any experience with the Power Acoustik Fire and Ice amps? I like the way they look, but I'm not sure about their performance. Thanks.

If you have 2 4omh subs, wiring is parall will creat a 2 omh load on your amp. If that amp will put out lets say 100W x 2(speakers in stereo) into 4omh, that would mean 200W x 1 mono into 4 omhs, if you wire your subs in parall creating a 2 omh load, then the amp will put out twice the power into 1 chanel at 2 omhs then it will at 4 omhs. You understand this? First of all you need to make sure that your amp will be stable at a bridged 2omh mono output. So you should look for an amp that will either put out 125W x 1 into a 4 omh load. or 250W x 1 into a 2omh load. Both are the same, just depends on how they rate thier amps. But most importantly: make sure the amp your are going to buy will be stable at a briged 2omh mono output. Email me if you need any more help or run into problems. sean@kdsi.net

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Sean Heberly
Silver 86 GT 2.8
Killer Stereo System

Ok, just want to make sure I got this right (or wrong)...

Let's say I have two 8 ohm subs wired in parallel that result in a 4 ohm load and these subs are rated at 125 watts RMS each.

I should look for an amp that puts out 250 watts RMS mono at 4 ohms?

Would the F14X-800 at the link at the bottom do the job even though the mono RMS is 220?

Is the RMS rating on the subs just a ballpark figure to aim for when choosing an amp?
http://www.poweracoustik.com/fire&ice.htm

Thanks for the help.

No, you do not want the F12X-800. Because: It is a 4 chan. amp, you can only bridge the 4 chanels into 2 separate chanels. You would want the F12X-400. It is only a 2 chanel amp and can be bridged to one chanel output. It will provide you with 220W R.M.S. into one chanel (your two 8omh subs in par.) They will divide equally and give you 110W R.M.S. per sub and 200W max. That is what you want. Although you understand that a mono output will mean that both the subs hit at the same time. Thats really not a huge deal. You will be wanting the F12X-400.

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Sean Heberly
Silver 86 GT 2.8
Killer Stereo System

I was actually looking for a 4 channel amp because I have pioneer speakers in the front and want to power them with an amp while bridging the rear channels for the subs.

So in that case, would the F14X-800 be the right choice? Or is it not possible to only bridge the rear channels on this amp?

Thanks.

Yes, you can bridge only 2 chanels of a 4 chanel amp. Thus creating a 3 chan. amp. But they would allow you 220W going to your subs and 90W going to each Pioneer Speaker. I am huge into Pioneer and I have a Pioneer System in my car, but I dont know of any Pioneer speakers with the exception of the PRS Midranges that can handle 90W rms. What are they? 4x10's? If so, they are rated at about 35W rms and about 120 max. I would recomend using two 2 chan. amps. But looking on the website you provided, the lowest amp there is 75x2, that will probally be to much. You might want to choose a different amp to run your Pioneers.

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Sean Heberly
Silver 86 GT 2.8
Killer Stereo System

I'm glad I asked so many questions before I bought the amp. I probably would have toasted my front speakers if you didn't clear that up for me. They are the 4x10's. I thought 35w rms and 120w max meant that you need at least 35w rms output from the amp and just as long as you don't exceed 120w you were good.

I have the cheapest Blaupunkt you can get (RPD 435). 35w x 4 max. 17.5w x 4 rms.
It says that the preamp output is 1.5 volts. I've seen some headunits with 2v and 4v preamp outputs. Is this number really important? Thanks.

Yes, good thing you asked. RMS is how much power your speakers can handle for extended periods of time. MAX is how much power they can handle for a very short period of time, usally under a second. Your pre-amp output is how much power is running throught the RCA outputs on the back of your stereo. With as little as 1.5V, you should only run one amp off that. I have 6.5V preouts on my unit, and even with that, I notice signal loss after just 2 amps. I am not sure about you specific stereo, but, do you only have one pair of RCA outs? If so, you are going to need a line driver, (It increases the power running in you RCA's so you have a good signal getting to your amps) if you are going to use 2 amps, probally about 4-6.5V. You should be fine if you just run that subwoofer amp off the RCA's and your 4x10's off the headunit. Granted your probally not go to have very good performance at high volums though. If I were going to do a small system in a Fiero. I would put some Polk Audio EX 4" midranges and tweeters up front and your subs (any brand will probally do) behind the seats, run your mids and tweeters off you headunit and amp your subs. Here is how my system is set up.

I am running 5 Premier Amps (Pionner's Advanced line of products is Premier) in the trunk. I have three PRS-X720's and 2 PRS-X320's. One 720 runs my 10" Polk Momo up front, another runs my 6.5 Polk Momo mids, and the last runs my 2 12's behind the seats, in par. at 2 omhs mono. On 320 runs my Pioneer 4x6 component plates in the rear stock locations. The other drives an 8" Polk DX Sub in the stock Fiero Subwoofer location. I am running Polk EX 4" mids and tweets up front off my head unit. The color code in the chart is as follows:
Green = Full range
Red = High Pass
Purple = Midrange
Blue = Low pass
If you already have the Pioneer 4x10's, you probally should either buy a small amp for them, run it off your speaker outputs from you stereo (Make sure this amp has somthing like "High Level Input" or similar, just meaning it can be hooked right in your stereo's speaker outputs, not using RCA's. Or not use an amp and just use your stereo to run them. And then buy that F12X-400 for the subs.

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Sean Heberly
Silver 86 GT 2.8
Killer Stereo System

[This message has been edited by Seanh (edited 10-01-2000).]

That's a huge stereo system you got there! Mind if I ask how much it cost you?

One last question (I think)...

I was looking at a subwoofer enclosure (link at the bottom). This one is 200w rms and 400w max at 4 ohm (has two 8 ohm subs wired in parallel). But the amp I want outputs 220w rms and 400w max at 4 ohm. Does this mean that the amp is too powerful and I should get the lower power F12X-300 that outputs 180w rms and 300w max?

I would prefer to buy a box with subs already mounted and wired as opposed to mounting them myself.

By the way, I was planning to stick the box where the passenger's feet would go.

Thanks.
http://208.49.57.143/is-bin/INTERSHOP.enfinity/eCS/Store/en/-/USD/RFDisplayProducts-Start;%24sid%24eU_S2CNYAQAzcuqO6obIqe2tvE4K9iLP?ProductSKU=Dual%2010%22%20RFZ%20Enclosure&Catego ryName=RF_SubwooferEnclosures

you might have to type in the last part of the url

[This message has been edited by kornholio (edited 10-01-2000).]

You should be okay using the F12X-400. Its only 20 watts more, and you will be find as long as you go easy on the bass boost and keep it at a low level. If that box will fit okay, then it looks good. My system drained me of $3722.00. I work at a stereo shop, so I got alot of the components for less then retail price. But thats not where the price ends. I still had the added expenses of sound matting, new carpeting to cover the midranges, All the wireing running from the front to the back and then back up front, A new batt., new alternator, 15 farad distribution system. Im still tweeking it a little before I begin competiting next year. Just be sure that box will fit where you plan to put it. It will work fine with the F12X-400.

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Sean Heberly
Silver 86 GT 2.8
Killer Stereo System