Cambridge CXN into Sansui AU-919

Discussion in 'Digital Sources' started by Multimode, Apr 5, 2017.

  1. Multimode

    Multimode Member

    Messages:
    61
    Location:
    Cambridgeshire, UK
    Having worked hard and saved hard over the years, I decided to treat myself to a Cambridge Audio CXN network player, received yesterday.

    I like the CXN very much, other than its sound level via my Sansui AU-919 amplifier being too high. At normal (not soft, not loud) listening level the amp's volume control sits at around the -50db level on a scale which runs from -70db to 0db over a rotation of about 320 degrees. Ideally it would be at about -20db as it is for other inputs.

    Cambridge Audio gave a same-day response to my email about this, suggesting I try the digital pre-amp that's built into the CXN. This reduced the signal through the RCA outputs, but by too much. The sound level was now too low even with the volume control screwed round to its maximum. From one extreme to the other. :(

    Ideally, I'd fit an adjustable attenuating device to the relevant input on the amplifier, but that's probably one of my sillier ideas!

    Any suggestions, please?
     
  2. Multimode

    Multimode Member

    Messages:
    61
    Location:
    Cambridgeshire, UK
    I may be able to answer my own question. Some research this evening has brought Rothwell Audio in-line attenuators to my attention, these reducing the signal strength by 10, 15 or 20 db, depending on the version bought. http://www.rothwellaudioproducts.co.uk/html/attenuators.html

    I also discovered, and many of you will already know, that amplifiers from pre-CD days had a much lower input sensitivity than later ones. The input sensitivity of the AU-919 is given as 150 mV whereas a CD player or network player is likely to push out 2 Volts or more, this overloading the amplifier's input and causing the problems I'm experiencing with my new toy.

    Do I get a prize for providing the answer? Is that how it works? ;) :)
     
  3. Multimode

    Multimode Member

    Messages:
    61
    Location:
    Cambridgeshire, UK
    I don't know about getting a prize for answering my own question, but I'm a prize idiot for not doing a search on AK before asking for help! Lots of info therein on in-line attenuators, if only I'd looked. :oops:

    All sorted now. I bought a pair of Rothwell -10dB attenuators which reduced but didn't overcome the problem. The Russ Andrews website suggests that, for 2V output into 150mV input, -16dB is required (http://www.russandrews.com/what-is-attenuation/). I emulated that by switching in the Jump control (with attenuators removed) which coincidentally gives -16dB. Much better but still not enough attenuation for some sources. I then tried using Muting (-20dB) and that gave a better result.

    Andrew Rothwell agreed without hesitation to replace the -10dB attenuators with -20dB, so I sent back the former. A pair of -20dB were dispatched to me next business day, by 1st Class post at their expense, and are exactly what was needed. The usable volume range is now between the 10 o'clock and 2 o'clock positions of the control, normally close to 12 o'clock (-20 to -16dB), and the sound quality is very noticeably improved now that the control is out of the original 8-9 o'clock range.

    The Rothwell attenuators are very well made and extremely good looking little gems; it's a shame they are hidden behind the amplifier! The Russ Andrews ones look similarly impressive but they cost 2.1/2 times more than the Rothwells.
     
    Last edited: Apr 20, 2017
    1koolcat likes this.

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