dmbr
100+ Head-Fier
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And what exactly is it for/does it do?
Is it meant to be used in conjunction with a "normal" amp?
Thanks
Is it meant to be used in conjunction with a "normal" amp?
Thanks

Similar to what Schiit's description says - it's passive, meaning it takes in no power and doesn't have any active (powered) components (e.g. a gain stage). Generally useful if you're connecting between a source (some have switches, or you can add a passive mechanical switch) that has relatively decent line output and a straight-up power amplifier. For headphones, not so much use because most all headphone amplifiers include their own volume controls.
There are also some tricky passive devices, like the CI Audio PLC1, which is remote controlled but still passive:
http://ciaudio.com/products/PLC1MKII
How does it work? It uses motorized pots and such, but it still isn't applying any active components to the signal. Most passive devices don't have a remote though, like the Schiit SYS. There's also some components that include similar functionality built-in; it was relatively popular on CD players for a while to have a second line-out with a pot for volume control to allow direct connection to an amplifier. Again, not much use for headphones, but if you want a simpler 2ch system it can be very useful.
If you're using a turntable that needs a phono preamp, that will be an active component, but you could still run the line output from there into a passive preamp and then onto your power amplifier.
Keep in mind that the passive preamp won't add gain, so you can only go quieter/lower-in-level than what your source provides - this may or may not be sufficient depending on the source, amplifier, and application, but IME tends not to be a problem for most CD players and amplifiers at least.![]()
KeithEmo Really Said Stuff
Weird - I hit quote and your entire post vanished. Anyways, I had wanted to respond and ask a question of my own:
- I've never actually seen, or even heard of, a transformer based "passive preamp" before.Got an example? (I'm curious now)![]()
- There are in-line volume controls that can work with headphones; Sennheiser and Koss make a few examples, and the Creative ACM that comes with some of their newer soundcards also functions as such (its just a pot between an amplifier and the cans).![]()
I'd like to put a passive preamp between my CA 752BD and an amp with 47kOhm impedance. What should be the imp. value for the passive? Thank you.