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Thread: Help me understand Passive preamps ?

  1. #1
    Join Date: May 2012

    Location: Dagenham Essex

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    I'm I'mteachingmarcotheartofpishanto.

    Default Help me understand Passive preamps ?

    Come on guys what am I missing

    You buy a box with nothing inside it , Some stepped rotary volume control knobs , A line select rotory knob

    some rca ins and outs , then you take out the std wiring and put in some silver wires

    And have spent £600

    Help
    Last edited by Audio Al; 20-03-2017 at 03:00.
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  2. #2
    Join Date: Aug 2010

    Location: East Midlands

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    I'm Hugh.

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    Quote Originally Posted by Audio Al View Post
    Come on guys what am I missing

    You buy a box with nothing inside it , Some stepped rotary volume control knobs , A line select rotory knob

    some rica ins and outs , then you take out the std wiring and put in some silver wires

    And have spent £600

    Help
    Yep, that's pretty much it.

  3. #3
    Join Date: Sep 2013

    Location: North Island New Zealand

    Posts: 668
    I'm Chris.

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    What you are missing is that stepped attenuators and switches are not
    the only forms of passive. To name a few, passives are also represented by Transformers, Fets and LDRs

    From the source component to the signal being delivered at the power amp input, start seeing audio being
    changed by every component that is attenuating. Not just accepting that its a box with a few parts inside

    You then will start to appreciate that a signal side switch or volume control changes the audio often very
    much for the worse, and cannot be recovered.

    It is far better if accurate audio is needed to have the attenuation done by a medium that does not involve rearranging the audio signal.
    Whilst that sounds like a conundrum - thinking clearly it is not at all.

    Rather all you need to do is create a variable resistor by using a medium that couples, without physically touching.
    because you are removing straight away the mechanical interface. Crudely one surface passing an audio signal
    grinding on another explains a stepped attenuator or potentiometer type.

    Coupling is not perfect either, but it is very close indeed when done properly.

    The very best attenuation involves a coupling medium separating the audio signal from the mechanical medium and that has properties
    preserving the audio signal and allowing the audio signal to pass untouched other than attenuating.

    Impossible ? not at all..

    Cheers / Chris

  4. #4
    Join Date: Aug 2009

    Location: Staffordshire, England

    Posts: 15,458
    I'm Martin.

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    Quote Originally Posted by Audio Al View Post
    :And have spent £600
    ....But got the sonic equivalent of an active pre-amp that would cost you several thousands...
    Martin



    Current Lash Up:

    Technics SL1200 with Sumiko h/s & Nagaoka MP50 * Firebottle valve MM phono stage * Parasound CDPi1000 * NVA P90SA passive pre / Krell KSA50S Power amp * JM Lab Electra 926 loudspeakers *


  5. #5
    Join Date: May 2010

    Location: Worcestershire, UK

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    I'm Rob.

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    Is that Chris talking or is it the devil's work ... look at the post number
    Rob.
    Powered by crossed fingers and clenched buttocks

  6. #6
    Join Date: Aug 2009

    Location: Staffordshire, England

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    I'm Martin.

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    Quote Originally Posted by ReggieB View Post
    Is that Chris talking or is it the devil's work ... ]
    A little from column A, a little from column B...
    Martin



    Current Lash Up:

    Technics SL1200 with Sumiko h/s & Nagaoka MP50 * Firebottle valve MM phono stage * Parasound CDPi1000 * NVA P90SA passive pre / Krell KSA50S Power amp * JM Lab Electra 926 loudspeakers *


  7. #7
    Join Date: Sep 2013

    Location: North Island New Zealand

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    I'm Chris.

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    Quote Originally Posted by ReggieB View Post
    Is that Chris talking or is it the devil's work ... look at the post number
    Just me, trying to be as good as I can

    Cheers / Chris

  8. #8
    Join Date: Oct 2016

    Location: Bolton, England

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    I'm Andrew.

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    Quote Originally Posted by Audio Al View Post
    You buy a box with nothing inside it , Some stepped rotary volume control knobs , A line select rotory knob
    some rca ins and outs,
    And have spent £600
    To put the cost into perspective you have to compare/contrast passive and active pre-amps. Both have to have a case, both have to have a front panel with lettering, both have to have in/out connectors, both have to have knobs... etc etc. In fact, there's essentially no difference in build costs between passive and active preamps except for the mains transformer (if there is one) and a collection of transistors/resistors/capacitors. True enough, a mains transformer can be quite expensive, but transistors and resistors and capacitors are (or can be) very cheap. So the idea that a passive pre-amp "has nothing inside" and therefore "should cost nothing" is a false one which doesn't stand scrutiny.

    What about performance? It's another marmite thing. Some people love passives, some people hate them.

  9. #9
    Join Date: May 2012

    Location: Dagenham Essex

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    What about performance? It's another marmite thing. Some people love passives, some people hate them.


    OK I see now
    Music , fills the gaps between silence !

    TAT Sale post Leader " Marcos Mentor "

    Also a pishanto specialist confirmed by Head Daftee

    Real name " Allen " or "Zoomer Nut”, “Numpty Napper”.

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  10. #10
    Join Date: Oct 2012

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    I'm Jez.

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    Quote Originally Posted by RothwellAudio View Post
    To put the cost into perspective you have to compare/contrast passive and active pre-amps. Both have to have a case, both have to have a front panel with lettering, both have to have in/out connectors, both have to have knobs... etc etc. In fact, there's essentially no difference in build costs between passive and active preamps except for the mains transformer (if there is one) and a collection of transistors/resistors/capacitors. True enough, a mains transformer can be quite expensive, but transistors and resistors and capacitors are (or can be) very cheap. So the idea that a passive pre-amp "has nothing inside" and therefore "should cost nothing" is a false one which doesn't stand scrutiny.

    What about performance? It's another marmite thing. Some people love passives, some people hate them.
    Spot on yes. £60 for the case and lettering and £10 for the electronics (cost price) for a basic SS active pre would be in the right ballpark.
    Arkless Electronics-Engineered to be better. Tel. 01670 530674 (after 1pm)

    Modded Thorens TD150, Audio Technica AT-1005 MkII, Technics EPC-300MC, Arkless Hybrid MC phono stage, Arkless passive pre, Arkless 50WPC Class A SS power amp, (or) Arkless modded Leak Stereo 20, Modded Kef Reference 105/3's
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