Mark Sealey

Q: iMac connected to external hifi/stereo system

I can successfully connect my Late 2014 5K iMac to my Parasound P3/A23 pre-amp using a mini-jack from the Headphone output to RCAs.

 

But there is a noticeable audio hum - particularly at higher volumes.

 

Anyone any ideas how to suppress that, please?

 

Thanks so much in advance :-)

iMac with Retina 5K display, OS X El Capitan (10.11.5), Clean machine... no haxies; no Microsoft etc

Posted on Aug 20, 2016 12:10 PM

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Q: iMac connected to external hifi/stereo system

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  • by Rudegar,Helpful

    Rudegar Rudegar Aug 20, 2016 1:19 PM in response to Mark Sealey
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    Aug 20, 2016 1:19 PM in response to Mark Sealey

    A Long analog audio cable will act the role of antenna which is likely what you experience you can try a shielded cable or get a digital one

  • by Mark Sealey,

    Mark Sealey Mark Sealey Aug 20, 2016 1:19 PM in response to Rudegar
    Level 2 (362 points)
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    Aug 20, 2016 1:19 PM in response to Rudegar

    @Rudegar - thanks, that's very helpful. I see.

     

    Do you by any chance have URLs (e.g. on Amazon) which suggest either product, please?

     

    Something like this, perhaps?

  • by dialabrain,

    dialabrain dialabrain Aug 20, 2016 4:52 PM in response to Mark Sealey
    Level 5 (5,845 points)
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    Aug 20, 2016 4:52 PM in response to Mark Sealey
  • by dialabrain,

    dialabrain dialabrain Aug 20, 2016 5:10 PM in response to Mark Sealey
    Level 5 (5,845 points)
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    Aug 20, 2016 5:10 PM in response to Mark Sealey

    Just looked at the P3 manual. It has no optical input so you would need to find a well shielded interconnect of sufficient length. The link you posted was for a coaxial cable. Not what you want.

  • by Csound1,Helpful

    Csound1 Csound1 Aug 20, 2016 10:48 PM in response to Mark Sealey
    Level 9 (50,202 points)
    Desktops
    Aug 20, 2016 10:48 PM in response to Mark Sealey

    It is most likely to be a cable issue, as Rudegar pointed out a long audio cable is an antenna (among other things) so it is prone to interference, how long is your connecting cable, and how is it terminated (I see RCA to minijack, but is a 3 connector minijack ( a TRS ) or a 4 connecter ( a TRRS), count the rings if you are not sure.

  • by dialabrain,

    dialabrain dialabrain Aug 20, 2016 5:24 PM in response to Mark Sealey
    Level 5 (5,845 points)
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    Aug 20, 2016 5:24 PM in response to Mark Sealey

    Just to add, your Parasound does have balanced inputs. However, the headphone jack in an iMac is unlikely to be balanced.

  • by Csound1,

    Csound1 Csound1 Aug 20, 2016 8:12 PM in response to dialabrain
    Level 9 (50,202 points)
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    Aug 20, 2016 8:12 PM in response to dialabrain

    dialabrain wrote:

     

    Just to add, your Parasound does have balanced inputs. However, the headphone jack in an iMac is unlikely to be balanced.

    Using balanced cables is a good idea, if you can unbalance  and connect a TRRS to them (which is a job for a pro)

  • by Mark Sealey,

    Mark Sealey Mark Sealey Aug 20, 2016 10:46 PM in response to dialabrain
    Level 2 (362 points)
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    Aug 20, 2016 10:46 PM in response to dialabrain

    Thanks @dialabrain!

     

    Do you have a link to a product that fits those requirements, please; 'well shielded interconnect'?

     

    It is long - at least 25'… all the way across the room!

     

    And I like the antenna theory. The hum increases and decreases as I work on my Mac!

  • by Mark Sealey,

    Mark Sealey Mark Sealey Aug 20, 2016 10:48 PM in response to Csound1
    Level 2 (362 points)
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    Aug 20, 2016 10:48 PM in response to Csound1

    @Csound1, thanks! can I not buy something which would use balanced cables and a TRRS… this is not my area of expertise?

     

    AFAIK, nothing special is terminating it at either end. How would I do that, please?

  • by dialabrain,

    dialabrain dialabrain Aug 20, 2016 11:35 PM in response to Mark Sealey
    Level 5 (5,845 points)
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    Aug 20, 2016 11:35 PM in response to Mark Sealey

    Mark, there is no way to realistically find a cable that would fix your hum. The only way you would be able to get a balanced output from your Mac is to have the hardware hacked by a professional and assuming you could even find one it would be expensive.

     

    I was going to suggest streaming to an Apple TV but it only has optical and hdmi which your pre-amp doesn't have. I don't know if anyone has a 'box' you could stream to from your Mac that has unbalanced RCA connectors or xlr balanced connectors to plug into the P3. I think what you are using now is close to as good as it is going to get without spending $$$.

  • by dialabrain,

    dialabrain dialabrain Aug 21, 2016 12:14 AM in response to Mark Sealey
    Level 5 (5,845 points)
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    Aug 21, 2016 12:14 AM in response to Mark Sealey

    I forgot to mention 25' or more is a very, very long distance to run an unbalanced line.

  • by Csound1,

    Csound1 Csound1 Aug 21, 2016 3:53 AM in response to Mark Sealey
    Level 9 (50,202 points)
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    Aug 21, 2016 3:53 AM in response to Mark Sealey

    You will need someone to build it for you, I doubt that such an odd duck will be available 'off the shelf'

     

    Your preamp lacks the facilities needed for a good connection, this much is clear. Placing it much closer would help but may not be possible.

  • by dialabrain,

    dialabrain dialabrain Aug 21, 2016 4:08 AM in response to Mark Sealey
    Level 5 (5,845 points)
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    Aug 21, 2016 4:08 AM in response to Mark Sealey

    FWIW, SONOS Connect may work but it's $349.

  • by Csound1,

    Csound1 Csound1 Aug 21, 2016 4:09 AM in response to dialabrain
    Level 9 (50,202 points)
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    Aug 21, 2016 4:09 AM in response to dialabrain

    On stage the rule was if unbalanced was unavoidable no more than 6 feet was acceptable, but it was always better to balance it. Consumer equipment tries to avoid the complication and cost of doing it correctly, often with untoward results like this.

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