[r_mitchell85]

Hi

I have a micro hifi system at work which we use to listen to CD's on.

For reasons I cba to go into, we need to be able to have one speaker going louder than the other....
The system has no balance control - (which would be perfect)

I've seen speaker volume control switches on ebay - but they all seem pretty pricey - about £30 upwards.

Surely there must be a cheaper way I can do this - or rig something up on one of the speakers?

Thanks, any advice appreciated.

[chrisjr]

For a micro system then this ought to suffice

http://cpc.farnell.com/_/lp-100-8/sp...ono/dp/LS00543

Mind you you'll have to make your own box for it

[r_mitchell85]

Quote:

Originally Posted by chrisjr

For a micro system then this ought to suffice

http://cpc.farnell.com/_/lp-100-8/sp...ono/dp/LS00543

Mind you you'll have to make your own box for it

Thanks!

This looks more like my price range! It doesn't need to be amazing quality sound. how would this work then?
how would I wire it up?

Also... how could I make a box for it?

edit - also would I want the stereo, or the mono one?

[chrisjr]

If you only need one speaker quieter then you only need the mono one. Wiring it is quite simple though does need some skill with a soldering iron.

If you look at the control it has three terminals. Look at it with the shaft facing towards you and the terminals at the bottom. The +ve wire from the micro system goes to the terminal on the right (5 o'clock position). The +ve wire to the speaker goes to the middle terminal (6 o'clock) and the -ve wires from micro system and speaker are both connected to the left terminal (7 o'clock).

You can get small plastic boxes from CPC which will do the job. All you need do is drill a hole for the control shaft in the lid of the box and a hole or two in the body of the box for the wires to enter. For example this one is just a bit larger than the faceplate that comes with the control

http://cpc.farnell.com/boss-enclosur...83?Ntt=EN55083

[r_mitchell85]

Thanks so much for your help.

I have also found this:
http://www.cableuniverse.co.uk/catal...-100v-70v.html

would this work too? it says its a 10W one... I've no idea what that means? they aso do 30W ones, but they are out of stock.

[chrisjr]

That is for a 100V line system. 100V line systems as the name suggests poke rather large voltages down the wires and use transformers at the speaker end to step the voltage down to something that won't send the speaker cone flying across the floor.

They are used in public address systems where you may need to run the cables a long distance. Easier to poke lots of volts but not many amps down a bit of wire, bit like why the cables hanging between electricity pylons run at several thousand volts not the 230 volts that comes out of the sockets on the wall of your home.

But totally unsuitable for a standard domestic audio amplifier.

[r_mitchell85]

Ok thanks - I understand now.

So the L-pad really is the only (and cheapest possibility) I'm going to check them out. thanks!

[r_mitchell85]

update, I've ordered the products you've suggested.
Looking forward to making it.

Thanks for all your help

[r_mitchell85]

so I shall be wiring it as you described, like this....http://i64.photobucket.com/albums/h1...udio/lpad3.gif

Is it ESSENTIAL that I get the negative a positive correct.... ie, I connected the +ive to one...... and sent the -ive through the l-pad using terminals 2 and 3? (if you get me)

reason is I cannot get behind the speakers (attached to wall) and I'm not 100% certain I observed polarity correctly

[chrisjr]

That is the correct wiring.

It would be better to get +ve and -ve the right way round but it would work if there were reversed. What you have to be absolutely certain of however is that you get the feed from the amp across pins 1 and 3. If you stick it across 1 and 2 then you will shortcircuit the amp when you turn the volume right down! Which would not do it any favours.

The cable between the amp and speakers should be coded, either with different colours for the +ve and -ve or a stripe down one side. And if the amp uses spring or screw terminals for the speakers you can work out which one is + and which - from there. Basically whichever is on the black terminal is -ve and whichever is red is +ve (assuming it uses the standard colour coding for the terminals). And the colour of the wires or stripe if there is one should follow the same convention.

[r_mitchell85]

Thanks.

The wire is coded & i think i kept the striped wise in the positive. But i cant be sure that i didnt accidentaly switch them over at some point during installation. I would need to take the speaker off the wall to check.

What I will certainly do is ensure i connect the hifi to 1 & 3. And then the speaker connects to 1 & 2 if i understand correctly. This should work?

[chrisjr]

If you just chop the wire at the point where you want the volume control mounted it makes it easier to get it all right. Just match the wire colours. But make sure you don't get the two ends confused. Perhaps put a bit of coloured tape round the wire from the amp as a reminder.

The important thing is that you keep the continuity of the wires from amp to speaker the same. So if you connect the stripe wire from the amp to pin 3 on the control you connect the stripe going off to the speaker on pin 3 and both "no stripe" wires to pin 1.

If you can get at the back of the hifi system and see how the wires are connected there it doesn't really matter which way round they are when they get to the speaker. Basically whichever wire is connected to the +ve (red) terminal on the back of the amp should be on pin 3 of the volume control and the wire on the -ve (black) amp terminal on pin 1.

Whether the stripe on no stripe wire ends up on the +ve terminal of the speaker doesn't really matter. Much more important to get the wiring from the amp the right way round.

[r_mitchell85]

Quote:

Originally Posted by chrisjr

If you just chop the wire at the point where you want the volume control mounted it makes it easier to get it all right. Just match the wire colours. But make sure you don't get the two ends confused. Perhaps put a bit of coloured tape round the wire from the amp as a reminder.

The important thing is that you keep the continuity of the wires from amp to speaker the same. So if you connect the stripe wire from the amp to pin 3 on the control you connect the stripe going off to the speaker on pin 3 and both "no stripe" wires to pin 1.

If you can get at the back of the hifi system and see how the wires are connected there it doesn't really matter which way round they are when they get to the speaker. Basically whichever wire is connected to the +ve (red) terminal on the back of the amp should be on pin 3 of the volume control and the wire on the -ve (black) amp terminal on pin 1.

Whether the stripe on no stripe wire ends up on the +ve terminal of the speaker doesn't really matter. Much more important to get the wiring from the amp the right way round.

Right. I can certainly get to the back of the stereo and see what wires I've got in there.

99% certain I put the stripe to positive terminal anyway.

Thanks for all your help. I think I know what Im doing now.

[r_mitchell85]

further update...

the stuff came this morning and I've just made the best speaker volume control I've ever seen in the whole world! Have tested it on my stereo at home and it works fine... just got to wire it upto the stereo at work next week

Thank you for all your help!