Got the MB Quarts..what next? - PeachParts Mercedes-Benz Forum

DaimlerChrysler · #1 06-03-2003, 08:37 AM

Okay, I bought 2 MB Quart DKD 110's and put them in my 84 380SL.
(I have a JVC CD head that says "180 watts High Power" on the face plate....it came with the car so there's no owners manual). The sound is wonderful at low volume levels, but if you turn it up loud enough to hear it with the top down they distort. One of my students who works at Circuit City says that I need an external amp because the receiver doesn't have enough power to operate at the volume I need. When I told him about the "180 watts and high power" he laughed and said that I should take the number, divide it by 4 then divide it by 10 and that's probably what the receiver REALLY puts out. (4.5 watts).

Does that make sense to anyone???? Do I REALLY need an external amp???What kind should I get? I listen to mostly classical music (I'm a music teacher!) and I'm not concerned about breaking glass with the bass!

Thanks!

Zeus · #2 06-03-2003, 03:50 PM

The 180 watts power rating is a joke. The marketing behind car stereo head units has become ridiculous to the point of being fraudulent.

My home stereo amp - a Marantz 1180DC - produces 90 watts per channel into 8 ohms with less then 0.03% THD (total harmonic distortion). It weighs about 50 lbs. Most of this weight comes from the power transformers. The power transformers step up the voltage to provide more power. The capacitors are also massive. Capacitors store power for when it is needed. You head unit probably puts out between 7-10 watts/channel at a reasonable THD rate. (I don't know your exact model).

How much does your head unit weigh?

The reality is that the small head units on their own do not usually have power transformers in them and have to rely on the 12V of power you provide them from your battery. That 180 watts is likely a peak measurement and not a more meaningful measurement (RMS). Your head unit is likely closer to 90 watts RMS (being generous), hence about 22 watts/channel RMS. This alone is not enough, the power rating must be measured alongside the total distortion being produced and into what load (resistance, measured in ohms). If the amp produces power that is distorted, then it will sound bad and it's not great for your speakers. This is what you are hearing when you crank it up and it sounds crappy. Is the unit capable of creating more volume? Yes. Does it sound good? No, because it is distorting. Why? It can't produce enough clean, continuous power for the load it is connected to (your speakers) at the level you are driving it at - the volume.

The bottom line is that if you want louder, undistorted sound coming out of your speakers, you will require an external power amp. The external amp will have a power transformer in it which will step up your voltage and allow more power to be sent to the speakers. This will produce a louder volume without distortion.

The efficiency of your speakers also plays a big role in the sound. The more efficient the speaker, the less power it requires to produce sound. Generally, you want the efficiency rating to be higher. If the rating is say, 88, it usually means that the speaker will produce 88dB of sound at a distance of 1 meter from an input power of 1 watt. The higher the efficiency, the less power you need to provide the speakers with to make sound. I would assume your MB quarts are quite efficient speakers. If you add a good external amp, they'll sound great.

I'll let someone else deal with the amp recommendation, I haven't bought one in a while! If I've fooked up any of my explanations here (quite possible as I'm working as I do this) please correct me!

Good luck.

DaimlerChrysler · #3 06-04-2003, 07:45 AM

Thanks for explaining it! I appreciate your response!

PaulG · #4 06-04-2003, 12:36 PM

DaimlerChrysler,

Your mechanic is right, with 12V form the battery and 4 ohm speakers, the most power you can get (without bridging) is 4.5 watts RMS. Any other figures are porkies.......

Unlikely to start any earthquakes

tecqboy · #5 06-04-2003, 10:05 PM

Anybody here remember the vibrator? No not that. How do you think they got the hundreds of volts required to run the tube type radios in those old cars with 6 volt systems?

Modern quality head units may use switching power supplies to do what the vibrators did. That is, step up the voltage of the power supply and thereby substantially increase the power output of the unit. True some power output claims are highly exagerated, but head units with true 30 watts RMS per channel into 2 ohms are available. Tod

JPL · #6 06-06-2003, 07:43 AM

Your next move, I think, should be an external amp in the trunk.

If you want to get more bass, go for a subwoofer mounted in the trunk below the deck and using either the first aid kit or the utility bin opening as a port.

I faced the same issue you are facing. I got mb quarts all around (4x6 in my case) and a Clarion amp. I realize the name clarion may wrinkle some foreheads, but they've come a long way in the past few years. Also, I had to think about the speakers I was driving (4x6) I didnt need a super expensive ultra efficient amp to drive 4 of these modestly sized speakers. So that configuration provides clean clear upper-mid range frequencies. Now the bass was adimitedly lacking. To get those low frequencies I use an Infinity Basslink Powered Sub.

I listen to music of all kinds, but mostly classic jazz, swing, and classical. I am very happy with the sound this all provides. I dont know how much you want to spend, but this was all done for around $650 P&L.

Poke around the forum here for lots of advice on components.

Have fun, and listen often.