What's a pre-amp...?

DocfosterDocfoster
in Amplifiers
;-) An almost genuine question...

Really I'm seeking clarity on what are the purposeS of a preamp.

I know that they:
1. Offer source selection and;
2. Control volume.

But I suspect they do other things too (some sort of buffering perhaps...?)...

I ask because I do not need the first 2 things. I have only one source and am entirely happy with JRiver's digital volume control. Until a few years ago I used a passive preamp (which I imagine does do only the first 2 things (the second by attenuation)).
When I went media-PC only I spent a while comparing JRiver's digital volume with the stepped attenuators in my passive pre- and decided that the digital volume was at worst as good as the SAs in the passive pre-. Hence I sold the passive pre-. Now my media PC feeds my power amp (currently the lovely One4 SECA) directly. Jriver hardly ever crashes, and when it has done it has always crashed silently, so I'm not worried about speaker damage issues.

But all this talk of SECA preamps is making me wonder what things an active design brings to the party.

Any information muchly appreciated. :-)

Comments

  • uglymusicuglymusic
    edited February 2016
    It's a great question. And one I've asked many times since I've stopped doing analogue.

    I've in fact used a passive for far longer than an active pre, and been very happy with the best of them, not having suffered with the attenuated bass and so on that people report.

    It's also, I think, a matter of using power amps for a long time that were designed for use with a passive.

    However, when Colin brought me the Listen to, er, listen to, I was very impressed. I works with the Green Goddess and God very well and, of course, with the Atoms that it was originally paired with.

    So, I'm wondering, why not have a SECA pre to go with the SECA powers? It seems to make sense.
  • DocfosterDocfoster
    edited February 2016
    Good to read your experiences in similar circumstances Dave, thanks. :-)

    I'd still like to know (though I admit hearing is more important!) what cutting the interconnects between my media PC and power amp and inserting into the gap a preamp (of whatever type) would bring to my already delightful party. I guess I just need to try it at some point.
    Clearly it would do something. And possibly something good. :-)
    I'm just being curious, genuinely, not challenging. :-)
  • uglymusicuglymusic
    I think you'll struggle to get an improvement, but in my case, I won't go pre-amp less because I don't want to blow up speakers again.


  • DocfosterDocfoster
    edited February 2016



    uglymusic said:
    I think you'll struggle to get an improvement, but in my case, I won't go pre-amp less because I don't want to blow up speakers again.


    I love the way that makes it sound like a frequent calamity...! ;-)

    Dave's speaker woes...

    image

    image


    image

    Never had you as a CV user, Dave...!
  • uglymusicuglymusic
    Docfoster said:



    uglymusic said:
    I think you'll struggle to get an improvement, but in my case, I won't go pre-amp less because I don't want to blow up speakers again.


    I love the way that makes it sound like a frequent calamity...! ;-)

    Dave's speaker woes...

    image

    image


    image

    Never had you as a CV user, Dave...!
    My cv is always up to date. I never know when I'll need it :-)
  • DocfosterDocfoster
    Very wise. Very wise.

    BTW, my sources elsewhere are informing me that the defining characteristics of a pre-amp can include:

    1. source selection
    2. volume and balance control
    3. optionally tone controls
    4. allows for things like tape loop connections for recording and playback
    5. impedance buffers the output (which passives can't do without affecting driving voltage or current)
    6. matches sensitivity to avoid over loading power amp stages and to ensure the opposite doesn't happen (ie too much gain at the power amp stage causing distortion).

  • cj66cj66
    edited February 2016
    1->6 That is pretty much my understanding of a pre-amp with the possible addtions of;

    7) easier connection to multiple power amps, if required.
    8) increased compatability over power amps.
    9) Remote control (for sources without)

    IME, if you are a single source user and have good compatability between your source and power amp along with an excellent volume control, there is no need for a pre-amp at all.

    BUT, I'm a multiple source user and.....did someone mention a SECA pre?
    O:-)
  • AntiCrapAntiCrap
    On site now.
  • DocfosterDocfoster
    cj66,
    Thanks for that. I am hoping that I don't need one. No preamp is, I suspect, somewhat cheaper than a good preamp.

    It's this matching source and power amp that interests me.
    From what I'm understanding from various places, this might be a measurement thing.

    My "source" is in fact the Xonar Essence STX sound card inside the NVA TFS media PC (as created by Jason "Figlet").
    The specs for that are here... clicky
    I think Jason played around a lot with the swappable OPAMPS during the design process. I can't remember which ones he ended up using. Do these effect specs relevant to the preamp...?

    My power amp is of course the very nice One4 SECA...
    Colin, how able are you to suggest the releveant specs there...?
  • DocfosterDocfoster
    AntiCrap said:
    On site now.
    Nice. :-)
  • AntiCrapAntiCrap
    edited February 2016
    Now you asked the question and here is the answer:-

    "A wet bit of string with gain"  

    Happy now 
    :D


    >:)
  • DocfosterDocfoster
    String and water i have. Where can i get me a "gain"...?
    ;-)
  • AntiCrapAntiCrap
    A downhill run maybe. :D
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