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Emerald phono stage: best way to get one or two extra inputs?

Discussion in 'd.i.y.' started by Rosewind, Jan 21, 2021.

  1. Rosewind

    Rosewind Lost in Translation

    I have an excellent-sounding Emerald phono stage here that I would like to expand to take one or two extra inputs from other tonearms. If it is possible, is there a preferred way to do this without sacrificing sound quality?

    My AD Audio Satchmo line stage has 4 inputs that are all used with DAC, tuner, cassette deck and Emerald phono stage, so I have no extra inputs available.
     
  2. a.palfreyman

    a.palfreyman pfm Member

    Selector switch in a metal box. 3 inputs for the arms, one output to phono stage. So long as all the screens (incoming and outgoing 0V) are commoned and connected to the metal box you shouldn't get hum problems.
     
    Rosewind likes this.
  3. Rosewind

    Rosewind Lost in Translation

    So basically a "passive pre" without a volume control?
    [​IMG]
     
  4. Arkless Electronics

    Arkless Electronics Trade: Amp design and repairs.

    But in a metal box! It also needs to switch both signal and ground to each phono socket.... Frought with issues really...
     
  5. Rosewind

    Rosewind Lost in Translation

    Any pointers, perhaps, then? I am not going to fork out a lot of money for this. I am trying not to feed the "upgrade dragon."
     
  6. Arkless Electronics

    Arkless Electronics Trade: Amp design and repairs.

    With MC carts you are trying to switch a "balanced" signal at low impedance and less than a thousandth of a Volt...
    Any lack of screening or less than perfect switch contacts and you will know about it! It's doable but asking for trouble really... and no specific recommendations no. If you can find a switch box intended specifically for this task that would be the best bet.
     
  7. Rosewind

    Rosewind Lost in Translation

    Thanks, Jez.
    Sounds like I will be back to switching between the 2 or 3 tonearms by hand, then.
     
  8. Sonny Beauceron

    Sonny Beauceron pfm Member

    On the other hand you now have good reason to buy at least a couple of additional amplifiers - another line pre and a phono stage with three inputs should do it - as you have exhausted all other possibilities and established that it's 'necessary'.
     
  9. Rosewind

    Rosewind Lost in Translation

    Last edited: Jan 22, 2021
  10. a.palfreyman

    a.palfreyman pfm Member

    Yes, sorry it did occur to me afterwards that the slightest click with 60 or more dB gain for MC would translate into a loud noise from your speakers. Someone on vynil engine recommended:
    https://www.esotericsound.com/elect.htm. scroll down to the 'rek-o-kut' low noise stereo phono selector switch. Works on MC carts but only two inputs.
     
    Arkless Electronics likes this.
  11. Rosewind

    Rosewind Lost in Translation

    Looks like a nice unit that would work with 2 phono signals or line signals. Thanks!
     
  12. a.palfreyman

    a.palfreyman pfm Member

    Not massively expensive either at about 70 USD (€60 or 50 notes.) When you get it, open it up and have a scooby inside. It seems it is simply a switch with "separated shields" so what Jez sez is very likely right. Therefore it will probably be a four pole switch so that all four wires i.e. 2 per each channel are all switched, removing the potential for earth-loop problems. If that is the case then you could build your own with a metal box and a good quality 4 pole 3 terminal rotary switch, copying that design. That way you only ever have one set of input wires connected to the output so as to reduce the chances of hum pickup.
     
  13. Rosewind

    Rosewind Lost in Translation

    I think I will just use a passive preamp or an input switch for the cassette and tuner inputs. That will free one input for a second phono stage. Now I have a Cambridge 640P on its way here and with two phono stages I will be covered until Jez converts the 640p to MC duty only. I believe before Jez wields his magic, I can use the Cambridge 640p with both MM and MC carts attached and switch between them.
     

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