BMW sound system and radio suggestions..

Hello!

     I put on my car (1983 635) the 8 speakers system (BMW sound System) with a Becker 830 (mexico diversity with code, produced in 1986-7) ...but sound is not so good:untill an average amount of volume is really good(a big improvement from old 4 speakers), when I turn up more the volume the speakers start to "pop" and to make strage noise then , sometimes, the speakers cut out(only when I turn up volume too much...).The volume is not so "heavy"...I tried to by-pass amplifier and installed the 8 speakers directly to the radio, and I reached a louder output than with amplifier

I tested the amplifier and seems in good conditions , speakers are like new(I removed those speakers from a car with 35k kms, sound system  but not the radio(!?!?)..It was a 1986 528i e28 owned by a 89 years old man..).

A radio repair center told me that those systems need a radio with 2x 20 W max output, or the amplifier will become a " distorsions-maker"...

Also a bad ground of power antenna could be a real problem

My radio output is currently doing 2x25  max ....

Does someone has got experience on those systems?

I do not have idea of the possible causes....

Thank You so much !

Francesco from North italy

Sohlman wrote: .....when you hear distortion it will be the speaker exspolding and you will need a new one. However when this happens it will probable be too loud for you to be able to handle......

Let this article be a warning to you

I expect demand for hearing aids to go up in the decades to come

Most car amplifier output stages are designed to drive a speaker load of 4ohms on each channel.

If you have eight loudspeakers, each 4ohms, you need eight amplifier outputs to drive them. Unless your units are paired in some way (e.g. as a tweeter and midrange unit with a crossover network) then you have no chance of driving all eight to a high volume unless you have eight outputs.

If you put several (say two) 4ohm speakers in series on each amplifier output channel then the current in each will be halved and the power in each will be quartered. As the volume is increased you will get 'voltage clipping' from the amplifier which sounds horrible.

If you instead put two 4ohm speakers in paralell on one output then again the amplifier will distort, but for different reasons. Again it will likely sound horrible except at low volumes.

If you wish to retain the existing system (in looks anyway) I would suggest one or two amplifiers, and as James suggests they should be able to take speaker level inputs, which is all you will get from your original head unit.

(However, if you are handy with electronics you can easily build a voltage divider network that will take the speaker level outputs and turn them into line voltage).

A pair of Sony XM-423SL amps will do the trick nicely; these will take the speaker level inputs, and are each adjustable for front/rear level, and bass frequency response. Best of all each is the size of a paperback book so can be hidden anywhere. Underneath the rear seats there  is loads of room.

Finally I would caution against the use of old loudspeakers regardless of useage; these would probably be made with paper cones (which deteriorate badly) and fairly stiff edge flexures. Modern loudspeakers can be much, much better than anything that could be bought twenty years ago.

I would upgrade the amplification/headunit first, and then look to the loudspeakers.

cheers