Hi Everyone, Just wanted to know is it possible to add to extra speakers to my K1100lt 1992 which has the standard clarion radio PU9203A in it. The radio only has output for two speakers so it it possible to some how convert 2 two 4? or piggy back 2 new speakers off the current speakers? I have no audio experience with amps either. I would like to keep the original radio as i cant cope with in helmet devices also I want to keep the remote control in the handle bar. Or is their a head unit that can use the original BMW remote control with a 4 speaker output? Thanks in advance! K.

You can add a fader control (a.k.a. dual potentiometer).  I've seen it done by installing one in one of the upper dash switch blanks.

Example: https://www.futurlec.com/Potentiometers/POT10KADUAL.shtml

A 10K pot wired as shown will only allow one set of speakers to work at a time, and only when the pot is at the end of it's travel.   That pot is designed for use in the signal path to a pair of stereo amplifiers.

Easiest solution is to check the impedance of the existing speakers.  It's probably 8 ohms, but might be 4 ohms.

Get a pair of speakers of the same impedance and wire them in parallel with the existing ones and go for a ride.

Point-Seven-five wrote:A 10K pot wired as shown will only allow one set of speakers to work at a time, and only when the pot is at the end of it's travel.   That pot is designed for use in the signal path to a pair of stereo amplifiers.

Easiest solution is to check the impedance of the existing speakers.  It's probably 8 ohms, but might be 4 ohms.

Get a pair of speakers of the same impedance and wire them in parallel with the existing ones and go for a ride.

Thanks i`ll give this a go I did`int thinks this would work but ill check what speakers i have thanks k.

The potentiometer can work, but:
Firstly, it needs to be capable of handling the power output of the stereo. Most common ones are 1/2 or 1 watt. The higher power handling ones are usually wire wound and consequently more expensive and harder to find.
Secondly, they need to be linear in their operation, not logarithmic. Otherwise an even sound balance will be almost at one end of its travel.
Thirdly, 10K is way too high, resulting in the one speaker or other effect as written by point-seven-five. In practice, it needs to be something around the impedance of the speakers.
Fourthly, if first, second and third are dealt with, there will be energy losses due partly to the extra impedance in the circuit and partly due to the mismatch between the output impedance of the amplifiers and the impedance of the potentiometer/speaker combination. Higher volume setting for the same sound level, and possibly driving the amplifier into distortion.

Point-seven-five's solution of putting a pair of extra speakers in parallel with the originals is probably best. 
Even better, if all 4 speakers are double the impedance of the originals, the amp output impedance and the wired-together-speaker-pair impedance will match. This is because wiring two equal impedances in parallel results in a net impedance of half of each individual one. 

Bill

"Get a pair of speakers of the same impedance and wire them in parallel with the existing ones and go for a ride."

Hmmm. Given likely age of individual (coupled with BMW ownership), this arrangement has a significant flaw ... 

How are they going to crank up Pink Floyd or Dire Straits and enjoy the full fidelity of quadraphonic swirling around their head whilst cruising down the road? Stereo just wont do.

Point-Seven-five wrote:A 10K pot wired as shown will only allow one set of speakers to work at a time, and only when the pot is at the end of it's travel.   That pot is designed for use in the signal path to a pair of stereo amplifiers.

Easiest solution is to check the impedance of the existing speakers.  It's probably 8 ohms, but might be 4 ohms.

Get a pair of speakers of the same impedance and wire them in parallel with the existing ones and go for a ride.

Hi I tried it and it works! Their are 2 clarion 4 ohms 45w speakers in it so temporarily wired up a speaker and it did the job! So I now need to work out what the max (power/vol/quality sound) speakers I can have are and put 4 in the bike (replacing the clarion ones if its worth it?) any suggestions anyone? Thanks again for your help! K.

If you are looking at replacing the original speakers, I would recommend getting four 8 ohm speakers.  That way the load impedance of two pairs wired in parallel will be the same as when there were only the two originals. 

A pair of 4 ohm speakers is a load of only 2 ohms, and that may cause problems with matching the output of the radio.

Point-Seven-five wrote:If you are looking at replacing the original speakers, I would recommend getting four 8 ohm speakers.  That way the load impedance of two pairs wired in parallel will be the same as when there were only the two originals. 

A pair of 4 ohm speakers is a load of only 2 ohms, and that may cause problems with matching the output of the radio.

Thanks for the advice I have a look on line K.