Buffered Pre-out? What is it?


I have a preamp that has a "normal" pre-out for short IC's and a "buffered" pre-out for long IC runs (not balanced). I assume the buffering is to keep noise down. What is the electronic or operational concept behind this type of buffering? Anyone know?

Thanks and Best Regards,
Jim
stilljd
You don't say what make and model of preamp is involved. Buffering in an analog circuit is usually done to make a circuit more tolerant of difficult load situations. (This is different than digital buffering, where data is accumulated in a memory chip and then parceled out to a device or program as needed.)

In your case it sounds like the preferred circuit is the unbuffered one, but that it doesn't tolerate the added resistance or capacitance of a long interconnect. In that case, the extra stage of devices (the buffer circuit) may offer the better compromise in terms of sonic degradation.
Mlsstl, It is an Arcam C-30. And yes, you are correct, the unbuffered out is stated as prefered.

It was more of a general question than a problem with implementation. I am familiar with the concept of digital buffering in the manner you describe. How buffering is applied in the context of a pre-out just had me grasping at thin air (mentally ciruit challenged :>)).

Your thought makes good sense. Do you know what would be used in a buffer circuit that would degrade the sound? Just extra connections?

Just curious.

Thank You! - Jim S.
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A buffer stage has a gain of 1 (or sometimes a slight attenuation). In general such a low gain circuit, either a tube (cathode follower) or a transistor, has virtually no distortion... certainly way less than the associated gain stages. A buffer output stage prevents signal deterioration due to loading of gain stages that have high impedance output, so it is puzling that the manufacturer says not to use it. Perhaps he is catering to those who believe that ANY additional circuitry is always bad. These folk ignore the loading effect on the "naked" gain stage.