Question about components, speakers, and choosing an amp - PeachParts Mercedes-Benz Forum

supermoose · #1 08-18-2006, 04:23 PM

If I decide to add components to the w124, which I think I am going to, I have a few questions about amplification. When choosing an amp do I want a 2 or 4 channel amp? For the wattage should it be around the peak wattage of the speaker? If I decide to amplify I would need more than one amp to amplify the crossovers and rear speakers yes? How does one wire in more than one amp and will I need to use a capacitor? I currently have a rockford fosgate punch 401s with two 10 inch rockfords on it. They are using 150 watts rms and 400 peak. I'm not totally sure what speakers I plan on getting yet, I'm leaning towards boston acoustics or polks. If someone could give me something general or even specific to work with so I can get an idea of how to shape up my system that would be great.

iwrock · #2 08-19-2006, 12:15 AM

I am a HUGE fan of the Infinity Speaker line. I have all infinity speakers in my car. They have crisp clean highs, and they sound great at high volume.

As for the amplification, I have two amps. I have a 4-Channel and a 2-Channel. They are both Alpine Amps (I think alpine makes some of the best amps). The 4-channel is an Alpine V12, and it has like 75 watts RMS. I get very clear highs and mids from my speakers. I have the amps gain turned down, otherwise my speakers make popping noises.

For my subs, I just used an alpine 600 watt amp to push them, and I get excellent bass from my subs.

As for wiring, I just used 4 gauge wiring from the battery into a distribution block. Then, it branches off into the amps. I also put the remote wire into a distribution block (a bit of overkill) and the ground is connected to a distrubution block as well. I have 3 sets of RCA cables coming off the headunit and going into the amps. My headunit has front, rears, and non fading subwoofer RCA outputs. I have them connected to these, and then they run back to the amps.

iwrock · #3 08-19-2006, 12:17 AM

Oh, and I have no capacitor. I dont think my system is large enough to need a capacitor. I dont get dim headlights or anything like that so i am good.

But just in case, I have a cap sitting in the garage.

Nate · #4 08-21-2006, 10:02 PM

caps are a waste of money, and a baindaid... you need to upgrade the alt if you get headlight dimming.

Setting the gains, is basicly programming the amp to the voltage of the headunit...

Say you have a megabucks 9volt preout headunit, you want your gains turned WAY down. Cheaper 2 volt preout, and it 1/2 way, or 3/4 of the way up... I think 1 volt is maxed out on most amps, but read the paperwork.

Just because you're setting the gains higher, doesnt mean it will get louder...

Turn the volume up to 3/4, and turn the gains up untill it distorts, then turn it down a click or two.

I have no preferance on amps, power is power (in most cases), just keep in mind if it sounds too good to be true, it's most likely over rated
good luck
~Nate

woodall33 · #5 08-22-2006, 11:35 AM

On the components, 2 or 4 channel amplification all depends on you. The 4 channel will give you more flexibility. Chances are, since you are asking this, I will assume that you are going to run your components passive...in this case, I would recommend a 2 channel, plus it will generally cost you less. Its going to do everything you need. Now on the flip side, if you are going to run your components active and skip the passive crossover that comes with them, then you'll want some sort of 4 channel, or maybe even a pair of 2 channels...but to keep things simple until you get more familiar with the in's and out's of audio, I would suggest running your components passive and build up and change your design from there. You may even want to just run coax speakers, and not have the hassle of components right out of the chute.

I wouldn't put too much stock into beefing up the rear speakers. Once you get your front setup done correctly, you'll find that by adding rear speakers can change the dynamics of the sound, and will pull the sound back (as in, not coming from as far in front of you)...when you start pulling the sound back, I think you'll agree that you won't be as happy with what you have. The sub will be fine in the trunk though, as true bass is not directional. Midbass frequencies can be, and as the higher you get, the more directional it becomes.

I wouldn't think you would need a capacitor. In some cases a capacitor can actually add load to your battery, so if its already struggling, you can be adding to the problem. Caps definitely have a time and a place, but not as a bandaid. If you are concerned about electrical demand, upgrade some wiring (engine block to chassis ground, battery to ground, alternator to battery). If that doesn't remedy things, upgrade your battery. Then upgrade your alt. But with a sub amp no bigger than that, if you do get a slight bit of dimming...I'll bet upgrading those wires will be all you need. It sounds funny, but it really does make a difference.

Before you buy a set of components for the front. Try to listen to them, if nothing else on a demo board. True they will not sound anything like they will in a car, but you will get a good idea of the range of the speaker (does it play relatively low with minimal distortion?, do the highs seem really harsh? how is the off-axis response? etc..) This will give you a decent idea of how tight you have to stick to the gnats ass when installing everything. Some speaker just do not work well at all when tossed into a moderate installion, but can really shine when done right. I think the Infinity recommendation is a good one, but you're not really going to go wrong with Polk or Boston either, they are all good brands. The Infinities can be very forgiving and still sound pretty good. You won't need a ton of power to run them either. 50 - 75 watts will be plenty for them. Once you have your gains set properly, I bet you'll like it.

I do disagree with Nate on the power is power comment. In a perfect world, yes 1 watt = 1 watt and their is no such thing as an amp adding coloration to the sound, etc... But you will find that companies do NOT rate their products the same, and do not use the same caliber of internals either. Why do you think a 75x2 Jenson amp costs $65 when something like a Tru Technology amp that would be of comparable specs costs $400 or $500? In most cases, you get what you pay for. Not always the case, but most times its true.

Can a headunit really have 40x4 power? When you look at a real 40x4 amp and see that the footprint is huge in comparison. That headunit is really only doing maybe 14x4 RMS, and RMS is what counts. Max power ratings are worthless.

The sky is the limit really, but keep it simple at first...it will sound better and be much less of a headache. If you want to tweak it after that, then get fancier and more technical.

Monomer · #6 08-24-2006, 09:13 PM

Major thing when looking into amps:

-True RMS power
-THD rating (.01%THD is standered)
-S/N Ratio (101db is top end)
-Dampning Factor (more the better)

Car audio is terrable when it comes to standeredized measurements. Most units are rated PMPO (which basically is, what it'll do if it were struck by lightning.)

You want an amp capable of 1.5x (atleast) the RMS power of the speakers, to prevent clipping and give "headroom" to the amp. Wattage isnt sound, and sound isnt measured in watts - another flaw in most car audio measurements. The only real way to tell how loud a system is going to be (or is) is by taking an SPL chart (1watt/1meter) which shows in graph form the power vs. sound.

If your looking to a sub box - I recomend Bill Fitz. designs, as they're the best sounding (lowest distortion/ highest SPL) boxes you'll find. I recomend the autotuba, if you have the trunk space http://71.18.23.29/AutoTuba.html I use a Tube30Slim for all my prosound needs - It'll do some damage to a house if you crank it. The good part about the design (folded horn) is that you get a lot of sound out of a little bit of power (sometimes even 10db more than "standered" sealed/ported boxes) 3db is equal to bumping the wattage 5x over; 10db is doubling the perceived volume (yes, these tubas are LOUD)