futique

Sorry for the n00b question.

I just got my Alpine components installed, along with my new 9857 HU, DCI, and iPod, and it's fairly clear upon listening that I will need an amp of some sort. (I can turn some tracks up to 20 without distortion, but beyond that, it sounds like shit. Some bass heavy kicks even fall apart at a volume level of 14- even with a flat EQ.)

Anyway- the speakers are rated at 50w, with 250w peak.

Unfortunately, I just discovered that the amp I was looking at (Fosgate Punch 25) has an output of 80w x 2.

Is this a recipe for disaster? Looking at the numbers, it would appear so, but I have heard that overpowering is less dangerous than underpowering.

If this won't work, can someone suggest a solid 50w x 2 that around the $200 range?

Thanks for all of your help!

thetz99

I am of the opinion that CLEAN, LOW distortion power is what you are looking for. Even if you get a monster power amp, it has gain controls that will limit the overpowering of low wattage speakers.

futique

OK... so do you think the Punch would work in this spot? I guess I am not quite sure what you are saying.

thetz99

Any separate power amp has its own "output" (gain) controls so you can control the amount of amparage to your speakers. ie amp rated at 200 watts/channel rms can be set to only output 20 if you want it to.

This same 200 watt amp will have a distortion rating at rated output of say .05 percent, but at 20 watts of output, the distortion level will only be .001 percent which is extremely clean.

The reason your system distorts now is because you are at or above the rated power of the internal amp (which also puts you at the high end of the distortion rating of the amp) and it is sending distorted signal to your speakers, which you hear as crappy sound.

VintageMac

Another reason your system is not sounding great is that you probably have a poor speaker enclosure - the doors.

Check out the thread that is also running: mods to doors

This is the correct way to seal your doors and maker a proper speaker enclosure - Dynamat (or equivalent) to dampen the vibrations of the sheet metal, and Ensolite to deaden the various panels and minimize refractions.

I was very unhappy with my Alpine / 80 watt amp / Diamond S600S component speakers as installed. The sound was distorted and there was no bass. After sealing the doors it sounded like a new, much improved, system. It now sounds like I am running a subwoofer (I'm not)!

This is an excellent reference piece for improving the quality of sound from your system: Sound Deadener Showdown

futique

Great replies. Thanks for the links!

I think I'll do a little more research and see what I can come up with.

It's tough deciding where to draw the line with audio ina car that has no top... It seems kind of crazy to spend the money on sound deadening, when the car is by nature, totally noisy.

Then again, why did I just spend ~$600 on a new HU and speakers?

It is a mystery.

futique

OK, so I just picked up an Alpine MRP-240 4/3/2 channel amp... Planning to install it tomorrow- but I have a few questions:

The amp is rated at 40w RMS per channel (~4ohms). I plan to bridge the amp, which will give me 100w RMS per channel- which should give me plenty of headroom to play with.

The question I have is in relation to the "bridging" instructions in the instruction manual. It seems straightforward, except that the illustration seems to be indicating that I should set the crossover to "LP" when I am bridging to two channels. (It has the wiring diagrammed, shows which terminals to use, and there is a little inset picture of the crossover attached which shows it set to "LP".)

This doesn't make any sense to me. I am trying to power components- not 2 subs. Is this a mistake in the manual, or am I missing something obvious?

If possible, I'd like to set this to HP, so that I can roll-off the bass at 80Hz!

Will

You should have crossovers switched off if you're running full range speakers, unless you want to run them high-pass and cut off frequencies below 80hz or so to prevent distortion.

Check out this post; this poster is doing the same thing as you, and there is a discussion on exactly how to run the inputs and bridge them.

https://www.s2ki.com/forums/index.php?showtopic=384390

EDIT: I must have blanked out--I didn't even notice that you already mentioned you wanted to run high pass--great minds think alike I guess! Having said that, nice color combo!

futique

Hey, thanks for the reply! My question isn't so much about the wiring, as it as about this stupid illustration. Why are they showing that the crossover selector set to LP? It doesn't make any sense to me....

Of course, Alpine doesn't answer the phone on the weekend, so I suppose my install is going to have to be postponed. #$&^@#!~!!!1

GSteg

they're showing LP because most of the time, people bridge the amp to get more power for their subwoofers.

You can set it anyways you like it, depending on your situation. If the illlustration was set to full range, those who are wanting to bridge their amp would think "why are they showing it in full range and not LP?

So Alpine gives the illustration according to what most people would do (bridging for subwoofer).

And there is no problem running an amp that is rated at 80x2 on a speaker that is rated for 50wrms. Music is dynamic. Your speakers will not get 80w constantly because power is affected by frequency, input voltage (volume knob), voltage from the battery, etc, and the content of the music.


And only if I saw this thread earlier. I have a Zapco Reference 200.2 that does 50x2 (underrated). Was gonna sell it for $200 also