Are the impedances not balanced throughout the audio band (and beyond)? My understanding is that they are since the closed loop output impedance of the opamp is "negligible", according Jensen application note.They ARE impedance balanced at DC
Can you post an example of an input circuit using this principle? The Jensen paper only shows an output circuit. All the input circuits in their examples are either transformer balanced or differential amps.They're not the kiss of death as line inputs
I don't have a picture handy, but basically you put a resistor from pin 3 to ground, with the value the same as Ri on the op amp buffer that is connected to pin 2. Pretty simple really.Can you post an example of an input circuit using this principle? The Jensen paper only shows an output circuit. All the input circuits in their examples are either transformer balanced or differential amps.
The pin-2/3 thing is fine and good in a fixed install, but in a live or combat audio situation, it's a problem. I'd NEVER use this in my studio. I have too much gear that has transformer inputs, or the oddball DBX quasi-floating inputs that PRR mentioned, to have it work reliably for me. I actually had to either banish or balance all of my unbalanced gear, mainly due to the proximity of a 50KW+ AM broadcast tower (WGN...4.02 miles away). Anything that had unblanced or IB connections picked up the station, right through the half-mile of Neglex that connects everything.What I got from Jensen, PRR and other's posts is that the circuit will "work" provided pin 2 is hot but isn't optimum. If pin 3 is hot you only have to swap two wires. But what is curious is that if you could somehow use this scheme throughout your studio wiring, you'd have lines radiating like mad yet all would be cancelled out at the input end!
Well, there are so many other circuits on their site that have big $$ trannys in them I have a hunch they're not worried.Funny that Jensen would suggest a circuit like this that uses <$2 worth of extra parts when they could easily try to sell you an output transformer.
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