Building a 5.1 audio switch box - use relays/semiconductor switches?

[gregmcc]

I've got 5.1 speakers on my PC - which has 3 connectors and another connector for the microphone.

I have now got a 5.1 gaming headset which has the same connectors so if i want to use my speakers I have to connect the 3 cables and then switch when I want to use my earphones.

I would like to build a switch box which seems simple enough, but after reading a few threads it seems not so simple.

Some people say use a extra sound card and then use the OS to switch sound card - I dont like this idea and prefer to build a switch box.

So I think I have 2 options.
1) Use relays?
2) I originally though it was going to be easy - use CD4066 to switch between the two, but after reading the on resistance of the 4066 can be up to 50R. Scratch that idea. A few threads have suggested using the ADG switches from Analog Devices which have a lot lower on resistance, but cost a lot more.

For the electronic gurus - which would you use? Relay/semiconductor switch/FET's?/transistor switch? Any thing simpler I should consider?

I could probably buy a switch box too - but where is the fun in that

 

[ericgibbs]

hi g,
I would use relays, this will ensure good isolation.
Reed relays are suitable for switching low level audio signals.
Also multi-bank rotary switches would be OK.
E

 

[picbits]

I've seen 4066 used extensively in some of the higher end hifi stuff. In fact some of the "Premium" equipment uses some very off the shelf parts !

 

[gregmcc]

hi g,
I would use relays, this will ensure good isolation.
Reed relays are suitable for switching low level audio signals.
Also multi-bank rotary switches would be OK.
E

Thanks - I didn't think about reed relays. Seems like a good option.

picbits - interesting. I thought the high resistance could cause issues.

 

[picbits]

Thanks - I didn't think about reed relays. Seems like a good option.

picbits - interesting. I thought the high resistance could cause issues.

The resistance is totally immaterial if you don't have a load on the other side of the switch.

Look at it this way. If you fed a DC signal through the switch and there was a 50 ohm load on the other side, your signal out of the switch would be half of what went in.

Put an opamp buffer on the other side and you now have a high impedance (>1MR) so your attenuation is going to be next to nothing.

It's all relative.

 

[4pyros]

In most cases a head phone jack will automaticy switch off the speakers when a head phone is pluged in and add the needed impedance matching resistance for the head phones.
I would consiter adding switched head phone jacks to the speaker system.

Kind of like this;

But you can do it with low level signals as well like just after the input cables enter the speakers before the amps.

 

[audioguru]

The fairly high non-linear resistance of a 4066 IC is fine when it drives a 10k ohm or higher amplifier's input. But it severely attenuates and distorts the sound from a low impedance speaker or headphones.
If the supply voltage is low (2v to 6V) then a 74HC4066 is a little better to drive the input of an amplifier.