Hi all,
I'm attempting an auto-recall patchbay project similar to Air Studios at Lyndhurst Hall patchbay with automated recall at Air on Twitpic. However, I have learned that they use the unused ground/shield connection and line in the patchcord for sensing - this can introduce noise as well as possibly lack of screening (depending on the circuit).
At present I see two options - one is to physically detect the presence of a jack, the other to switch out the audio and flash through the jacks with a dc signal. I prefer the latter as I can then store routes rather than just a series of inserts - and even write the connection names on an LCD. The former has been used before - there is a patent to use optical sensors - but it would have to be constantly recording and interruptions in power and or sequence throughout the session could cause major problems.
So, I need a very high quality audio SPDT or DPDT switch, with very low THD and crosstalk (if in a multiple package). I originally suggested doing it all electronically and using analog crosspoint matrices but this was rejected due to the above conditions - plus "Air doesn't do it that way"! I have though of relays, but apparently even gold-plated sealed ones degrade rapidly as they use 'dry' contacts. The audio must not be touched in any way either - so DC biasing is out of the question. I can only think of reed relays or solid state possibly...
Any thoughts would be greatly appreciated!
Laurence
I'm attempting an auto-recall patchbay project similar to Air Studios at Lyndhurst Hall patchbay with automated recall at Air on Twitpic. However, I have learned that they use the unused ground/shield connection and line in the patchcord for sensing - this can introduce noise as well as possibly lack of screening (depending on the circuit).
At present I see two options - one is to physically detect the presence of a jack, the other to switch out the audio and flash through the jacks with a dc signal. I prefer the latter as I can then store routes rather than just a series of inserts - and even write the connection names on an LCD. The former has been used before - there is a patent to use optical sensors - but it would have to be constantly recording and interruptions in power and or sequence throughout the session could cause major problems.
So, I need a very high quality audio SPDT or DPDT switch, with very low THD and crosstalk (if in a multiple package). I originally suggested doing it all electronically and using analog crosspoint matrices but this was rejected due to the above conditions - plus "Air doesn't do it that way"! I have though of relays, but apparently even gold-plated sealed ones degrade rapidly as they use 'dry' contacts. The audio must not be touched in any way either - so DC biasing is out of the question. I can only think of reed relays or solid state possibly...
Any thoughts would be greatly appreciated!
Laurence