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Thread: Rothwell attenuator question

  1. #1
    Join Date: Apr 2016

    Location: Bishops Stortford

    Posts: 1,250
    I'm Chris.

    Default Rothwell attenuator question

    The output of my CD player is a bit too high for my integrated amp meaning the volume control on the amp only works over a small range before being too loud. I am led to believe this may be causing some distortion to the music, although that is not immediately obvious.

    The general recommendation is to use in-line attenuators like Rothwell, but I have a spare passive volume control that I could put in line before the integrated. Is there anything that I should be aware of with this approach? This would only be a temporary fix but it might give me a handle on whether permanent changes are needed.

    Source
    SW1X Universal Music Server UMS I Signature with Power Supply Unit PSU I Signature
    SW1X USB II
    SW1X DAC III Special
    Audiolab 6000 CDT transport
    Amps
    Pre amps -- Hi fi Collective twin mono ladder stepped attenuator, with Charcroft Z-foil and silver wired. And First Watt B1 active no gain buffer.
    Power amps -- Welborne 45 SET monoblocks 1.8W / Decware Taboo 6W / Elekit 300B TU-8600SVK plus further improved components 9W / ICE Power 1000W
    Speakers
    Highly modified Endorphin P17 open baffle speakers containing both vintage and modern alnico drivers and paper cones. All silver wired - 8" Cube Audio FC8 full range drivers and vintage 15" Altec VOTT 416 bass drivers. All sat on Townsend Audio Podium seismic isolation platforms.
    BK Electronics XLS400FF Sub.
    Cabling
    Silver mains cables, interconnects and speaker cables by SW1X
    Headphones
    HRT HeadStreamer and SennHeiser HD650 headphones

  2. #2
    Join Date: Sep 2013

    Location: North Island New Zealand

    Posts: 1,757
    I'm Chris.

    Default

    Hi Chris
    If using a passive volume control, try it at half volume as it should if its a conventional attenuator provide equal resistance from your source, and
    the same value of resistance to ground. In electrical terms it is a L pad. The RCA solution is likely to be internally also two resistors doing the same thing
    but may be higher or lower in resistance, this is where a multimeter comes handy to check.

    The passive volume control you have, therefore is a neat solution, let us know how it goes.

  3. #3
    Join Date: Apr 2016

    Location: Bishops Stortford

    Posts: 1,250
    I'm Chris.

    Default

    Thanks Chris

    The advertising for these attenuators targets distortion caused by overloading the amps. I cant get my head around how one can still 'overload' the amp if the volume is right down to low levels. Surely this negates the overload.
    Source
    SW1X Universal Music Server UMS I Signature with Power Supply Unit PSU I Signature
    SW1X USB II
    SW1X DAC III Special
    Audiolab 6000 CDT transport
    Amps
    Pre amps -- Hi fi Collective twin mono ladder stepped attenuator, with Charcroft Z-foil and silver wired. And First Watt B1 active no gain buffer.
    Power amps -- Welborne 45 SET monoblocks 1.8W / Decware Taboo 6W / Elekit 300B TU-8600SVK plus further improved components 9W / ICE Power 1000W
    Speakers
    Highly modified Endorphin P17 open baffle speakers containing both vintage and modern alnico drivers and paper cones. All silver wired - 8" Cube Audio FC8 full range drivers and vintage 15" Altec VOTT 416 bass drivers. All sat on Townsend Audio Podium seismic isolation platforms.
    BK Electronics XLS400FF Sub.
    Cabling
    Silver mains cables, interconnects and speaker cables by SW1X
    Headphones
    HRT HeadStreamer and SennHeiser HD650 headphones

  4. #4
    Join Date: Sep 2013

    Location: North Island New Zealand

    Posts: 1,757
    I'm Chris.

    Default

    Hi Chris
    Yes attenuation certainly does negate the possibility of overload. Most amplifiers provide for CD levels. If we measure a typical CD players
    output it cruises along most of the time, at about 200mv only a 10th of its true capability for delivering output voltage and current. But there are CD's
    that will use all of the available level, like about 5 mins in to Mike Oldfields Amarok .... have you heard that one ?

    Any given amplifier, really does NOT need to amplify a CD input, rather just variable attenuation is sufficient to pass to its power amplifier stage
    or to a separate power amp. Hence you can keep the CD audio as clean as possible by not adding or subtracting from its enormous capability.
    There is more on the wee silver disc's than we casually appreciate. although i do have some criticisms of it, they are minor.

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