Can I play both channels of stereo amp through one speaker?

[crackle]

My suspicions were confirmed, the problem is the central speaker (the one in the main unit) is open circuit. With the bench speaker connected to it the audio is really quite good quality.

When the 2 external speaker speaker DIN plugs are inserted the central speaker changes tone to more bass, well probably less treble to be more correct. So it looks like there are occasions when it is possible to connect the outputs of 2 power amplifiers together.

It is quite a busy circuit board inside the unit, you can get a feel for the size of the thing, the battery compartment takes 8 D size batteries

Mike

[crackle]

Originally Posted by Scimitar

Often, the "centre" speaker is nothing of the sort. It gets wired between the left and right channels positive. That gives sum and difference output, or "poor man's surround".

Looking at the circuit diagram I posted in #13, in this case it looks as if it is just the sum of the outputs, the same as if you had joined the left and right channels of a music source, via a couple of suitable resistors, in order to make mono.

Mike

[MotorBikeLes]

Connecting a third speaker between the two main outputs gives a difference signal, a sort of quasi-stereo, known as the Haffler system, probably named after a Mr (or Herr) Hafler. It normally has a volume control to limit output which could sound un-natural if over done.
Les.

[crackle]

In this case, it sounds completely natural just like joining the 2 channels of your MP3 player via 2 x 2k ohm resistors and feeding the resultant signal into the input of your old radio.
Note, in this case the 3rd central speaker is connected between the summed outputs and ground.

Mike

[indigo.girl]

Originally Posted by Nickthedentist

If you need mono, look at the cheap Chinese kits that use the superb TDA2030 IC.

Hi Nick - I've been following up your suggestion about a TDA2030 mono circuit (for another project I have in mind). So far the only circuits I have seen only have volume control and no bass/treble controls which I'd like if possible. How easy would it be to modify to include tone control?

There a basic circuit diagram here. I presume it wouldn't take much to add tone control? ps - this website must use automatic language translation - but you kind of get the gist

http://www.eleccircuit.com/the-multi...using-tda2030/

[ms660]

Graft in a Baxendall tone control circuit:

http://www.elcircuit.com/2011/04/tda...e-control.html

How it works:

http://www.learnabout-electronics.or...plifiers42.php

Never done that myself but it should work.

Lawrence.

[indigo.girl]

Fantastic - I'll order some components and give it a go