I have a question regarding the sound quality of an opamp in unity gain (LT1128), does anybody think it is worth making a pass b1 or other discrete unity gain buffer circuit. Or would the opamp be good in this spot in the circuit since its operating in unity gain.
application details are everything
the LT1128/1115 are the internally unity gain comp, "audio" speced versions, can use external compensation C on the 1028 for unity gain stable operation
these are optimized for ultra low V noise with low source Z - above a few 100s of Ohms the Inoise can make them worse than other choices
the high bias of the input diff pair make them relatively RFI immune for a BJT input op amp
and they have 500 uA output bias and should provide up to 1 mA push-pull Class A - about 5x better than many "audio" IC op amps
but the typical application of super low Vnoise op amps is to amplify - not unity gain buffer
the LT1128/1115 are the internally unity gain comp, "audio" speced versions, can use external compensation C on the 1028 for unity gain stable operation
these are optimized for ultra low V noise with low source Z - above a few 100s of Ohms the Inoise can make them worse than other choices
the high bias of the input diff pair make them relatively RFI immune for a BJT input op amp
and they have 500 uA output bias and should provide up to 1 mA push-pull Class A - about 5x better than many "audio" IC op amps
but the typical application of super low Vnoise op amps is to amplify - not unity gain buffer
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Do you think that the simple opamp unity gain buffer with salas shunt can beat (transparency) the pass b1 or other unity gain buffer.
circuit's suitability depend on input V level, and impedance - I wouldn't use a LT1028 to buffer a 50K Volume pot with 2 Vrms audio signal
then what load it drives can make a difference - 16 Ohm iem headphone, or 200 ft of twisted pair into a remote amp?
then what load it drives can make a difference - 16 Ohm iem headphone, or 200 ft of twisted pair into a remote amp?
My input is a ad1865/pass d1 preamp then 20k stepped attenuator then the lt1128 then a dx precision i amp with a 15k input impedance. What would be the optimum opamp for that.
The cables are about 5ft each
The cables are about 5ft each
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its only a little more than 1 dB error at the midpoint to just connect them up without a buffer
since the error is smoothly distributed over the steps you really would have exceptional hearing to be able to tell without the buffered version to test side-by-side
and even if you could tell its just another slight variation on the volume curve - several variations are popular, hard to say any one is "right"
since the error is smoothly distributed over the steps you really would have exceptional hearing to be able to tell without the buffered version to test side-by-side
and even if you could tell its just another slight variation on the volume curve - several variations are popular, hard to say any one is "right"
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