Are relays or analog switch IC's better for audio switching?

[Speakerguy]

Hi!

The title says it all. I need to select a stereo source from among several stereo inputs. Are relays or analog switch IC's better in terms of linearity/THD? I see that some relays spec minimum switching loads (mV/uA range). What does that specification mean? And what type of relays should I be using for audio signals?

I have found some analog switch IC's that go anywhere from 50c to 7.00USD. They all have low distortion (<.01%) at 0dBR 2.83V, but the less expensive ones show greatly increasing distortion (straight line) at decreasing signal levels. Crossover distortion or noise, not sure which.

Anyway, any and all help is appreciated. Thanks!

 

[audioguru]

Some switches and relays have silver contacts rated for a high current. When the silver corrodes then they switch high currents fine due to the spark breaking through the corrosion, but don't switch mV/uA signals. Gold contacts continue to switch low levels perfectly and the gold is a thin plating so it costs the same as silver.

I have seen switches and relays (with gold plated contacts) in very good audio equipment but not solid state analog switches with their distortion.

 

[Nigel Goodwin]

I would agree, it's easier to get higher quality with relays than analogue switches.

Going back to the 60's/70's the British HiFi manufacturer Leak wouldn't even use push button selectors because they weren't of high enough quality, and continued to use rotary switches.

There was an amp in the 70's, quite highly respected (I've forgotten the make now), it used diode switches and FET's to do the input selection.

 

[Speakerguy]

Thanks guys, answers all my questions. It looks like the only audio IC that would really compete with relays would be the expensive SSM2404 from Analog Devices, and it's more expensive than an equivalent relay at 4.00 in large quantities.

 

[christopherjoel]

Did you ever find a good relay to use? Which one and where'd you get it?

 

[power58]

CD4066 analog switches work OK if you use a bipolar power supply +5/-5 +12/-12 ect.
for chip power.Built a input switch box with them.

 

[ecerfoglio]

CD4066 analog switches work OK if you use a bipolar power supply +5/-5 +12/-12 ect.
for chip power.Built a input switch box with them.

If they have the usual 3 to 18 V specification of the CD4000 series, then the maximum bipolar voltage would be +/- 9V (+9V / -9V)

A +/- 12V supply will give 24V to the CD4066