Passive preamp

bluetosman
What is passive preamp and how to connect them

A passive preamp controls the volume of the source just like an active preamp, except there’s no added gain, which means no added noise or coloration’s or distortions, they use all the gain that the source has to offer instead of throwing most of it away away.
They replace an active preamp and go in the same position, between the source and the power amp.

Quote from Nelson Pass

We’ve got lots of gain in our electronics. More gain than some of us need or want. At least 10 db more.

Think of it this way: If you are running your volume control down around 9 o’clock, you are actually throwing away signal level so that a subsequent gain stage can make it back up.

Routinely DIYers opt to make themselves a “passive preamp” - just an input selector and a volume control.

What could be better? Hardly any noise or distortion added by these simple passive parts. No feedback, no worrying about what type of capacitors – just musical perfection.

And yet there are guys out there who don’t care for the result. “It sucks the life out of the music”, is a commonly heard refrain (really - I’m being serious here!). Maybe they are reacting psychologically to the need to turn the volume control up compared to an active preamp.

Cheers George

Its just a none powered, zero gain stage, usually for source selection and volume control. basically its a volume pot, switch and in-output connections in a box. Hook it up like a regular preamp source in - amp out. 

Passives adds little to the signal ( minimaly a volume  so that's the attraction. there is advantages and disadvantages with either passive or active preamps.

A passive preamp is one which has no amplification and provides an input selector and a volume control. In theory, the passive preamp has no distortion since there are no active devices (transistors, tubes, etc.) providing amplification. The output impedance can be quite high compared to an active preamp and, as such, is very sensitive to capacitive loading. Low-capacitance interconnects are mandatory to avoid HF rolloff and loss of dynamics.