Car stereo advice - Sarb11
About to fit a new stereo is it possible/wise to try and connect 6 speakers to a stereo that is designed for 4 x 40w output i.e 4 speakers.
Car stereo advice - Kuang
You can try to muck about with different speaker values and the like, but tbh I'd say it really isn't worth it. Safest way is going to be to fit a separate amp and use that to drive the extra two - maybe run the front output to the front doors, the rear output to the amp, and then split out from the amp to the rear doors and parcel shelf, or similar.
Car stereo advice - M.M
Depends a bit on the layout. Often with six speakers only four are midrange/bass units, the other two are tweeters. If so the tweeters will usually be "piggy backed" onto the front speakers and you can safely use this set-up with a four channel amp.

M.M
Car stereo advice - Dynamic Dave
Unless the extra speakers are tweeters, then I wouldn't advise it. Most, if not all car stereo's and their speakers are 4ohm rating per individual output, so by adding an additional speaker will reduce that figure to two ohms, or increase it to eight ohms - depending on whether you wire them up in parallel or series. By doing this, you could possibily end up blowing the amplifiers in the stereo.
earth connection - Sarb11
Just finishing of fitting my car stereo with one slight problem. The black lead from the stereo is supposed to go to the earth connection. I have got three wires in the centre console that could be the earth connection. Brown, grey and white/yellow.

On connecting the black wire to the brown my battery blew! Not to worry it is knackered anyway and does not hold a charge for more than 24 hrs. (i have a new one to fit once stereo complete!)

On connecting the black wire to the grey my fuse for the dashboard lighting blew!

On connecting the black wire to the white /yellow nothing happens, the stereo works fine it works fine without connecting the black wire at all as well. How can I check that it is wired to earth.? I am pretty sure that the black lead was previously connected to the brown or grey wires? Also in the manual all the wires going to earth are brown.

I am confused!!!!
earth connection - Sooty Tailpipes
The black wire is the -ve connection, as the car is -vely earthed, the radio also takes this from the ground on the aerial, but you should still connect the black wire to earth to avoid power dropout and inteference.

When you connected the black to the first two wires, they were obviously +12v and were shorted to -ve through the streao's aerial lead.
earth connection - Ivor E Tower
Take the black lead to earth directly, find a screw that goes into the body somewhere, undo it a few turns and place the bared end of the wire under it. If you want to do it "properly", crimp or solder a tag to it first.
earth connection - Sarb11
Managed to solve the earth problem. Next question is my stereo say 4 x 40W. I am thinking of changing my back speakers what are my limitations regarding this? Do they have to be a maximum of 40W?
earth connection - Dynamic Dave
Next question is my stereo say 4 x 40W.
Do the speakers have to be a maximum of 40W?


Quite the opposite in fact. They have to be a minimum of 40W.
earth connection - Sooty Tailpipes
Make sure your wattages are of the same method of mearurement.
ie RMS (route mean squared) or PMPO (Peak Music Power Output
There are other lesser used ones too.

With regards to wattage, don't get speakers way over the wattage of the head unit, or what will happen, is you will get clipping, this is because the impedance of a speaker changes with frequency and thus rate of deflection, so a small amp will not have the oomph to physically move a heavy voice coil and speaker cone, even though they are more than capable of handling the wattage. get speakers designed to be driven by a head unit, not a power amp.

Also, go for quality branded, good spec ones, not ones that have a dramatic name, take up a lot of space and are over-designed (all gloss and no substance),
earth connection - Sarb11
Thanks DD. What would happen if they are less that 40W?
earth connection - Sooty Tailpipes
Well, when you turn them up past their rating, the sound would distort so much you would turn it down, but if you didn't it may damage the speakers or radio with prolonged abuse, but nothing dramatic, just degrade them or make them faulty. You radio's rating of 40W will probably be PMPO, as 40W RMS is too high from a head unit, I think most speakers can handle 40w.
earth connection - Altea Ego
If you put more than 40 watts of power through the voice coil of a speaker rated at that, you will overheat the coil, and the coil will seperate from the cone. The coil gets hot and the bonding/glue breaks down. Done it twice.
earth connection - Ben {P}
Renault family is right but dynamic dave is quite wrong to say the speakers have to be rated at a value equal to or higher than the quoted max power available from the amp.

From Sooty tailpipes above:
"With regards to wattage, don't get speakers way over the wattage of the head unit, or what will happen, is you will get clipping, this is because the impedance of a speaker changes with frequency and thus rate of deflection, so a small amp will not have the oomph to physically move a heavy voice coil and speaker cone, even though they are more than capable of handling the wattage. get speakers designed to be driven by a head unit, not a power amp.

Also, go for quality branded, good spec ones, not ones that have a dramatic name, take up a lot of space and are over-designed (all gloss and no substance),"

I can't agree with any of this. Speakers are rated accoring to the thermal capability of the voice coil as RF states. Having speakers with a high power handling on an amp with a small power rating will not necessarily cause clipping. How easy or difficult a loudspeaker drive unit is to drive depends a lot upon its sensitivity, this is not necessarily related to its power handling ability.

Clipping occurs when the amp cannot handle the current it is being asked to produce. If an amp clips trying to output 20w at 50hz it will clip at exactly the same point on speakers rated at 30w or 3000w if the impedance at that frequency is the same.

Regarding drive units. There are only a few companies in the world that make real quality loudspeaker drives. All the coaxial drivers you will find in places like halfords sound dreadful. Often these speakers have no cross-over at all on the woofer. Avoid.

The impedance figure on a drive unit is either a meaure of the lowest impedance fugure on the curve (the resistance of a drive unit changes with frequency), or the impedance at a given reference point (say 1K) which is often near the bottom of the curve. But even on the best drive units the quoted figures can be incorrect.

The power handling of any drive unit depends upon the signal fed to it. To generate 1 90db sound at 50hz a 6.5" drive unit will have to move 400 times the distance than it would when emiting a 1k signal at the same sound pressure level. So if two people had the same drive unit, one could drive the unit with 10w with no filter and have serious distortion, and one could drive the same unit with 20w, but have a high pass filter at say 100hz, and have greatly less distortion. This intermodular distortion is what people will be hearing. IF you exceed the power rating you will simply damage the speaker and it wont work properly any more.

Some people in the hi-fi community favour valve amps. I have heard ear splitting levels in large listening room using amps of only 10-15watts.I drive my speakers with a 105watt RMS (into 8 ohms) amp, and cant get anywhere near the levels.

speakers - Sarb11
Thanks for all the posts. Having read all the above I am still slightly confused. What would be best for head unit that says 4 x 40W?
speakers - Civic8
If you go for a speaker on or around 50 watts rms there won`t be a problem.Just make sure when buying the rating is rms root mean square means same value in volts it`s that simple
 

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