Question Phono Issue

Discussion in 'Hi-Fi Stereo Systems & Separates' started by innersleeve, Jan 4, 2019.

  1. innersleeve

    innersleeve
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    Hello, I have a Camridge Audio A1 MK 3 Amp with a DUAL CS 505-4 Belt Drive turntable, connected to a pair of Gale speakers. There is no sound coming out of the speakers when playing vinyl but can hear some sound coming from the stylus. Please can someone advise what I need to do. Thank you.
     
  2. Ugg10

    Ugg10
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    Does your amp have the optional phono input. If not you will need a separate phono preamp. These can be had from £25. Does it work with other sources, you can use a phone/tablet or cd/dvd player to check if it is ok. If the phono/aux input is the same volume as the rest with a cd/tablet then you do not have a phono card installed, if it is significantly louder then it is.

    https://techsupport.cambridgeaudio..../200148821/A1_User_Manual_-_All_Languages.pdf

    It will have one of these installed
    cambridge audio integrated amplifier - a1 mk3 special edition 2 cambridge audio - Hifishock

    Without plugs into the space at the bottom left of the picture.

    upload_2019-1-4_23-3-55.jpeg
     
    Last edited: Jan 4, 2019
  3. innersleeve

    innersleeve
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    Thank you. Yes, it does have a phono output. I have played my phone through the amp and it appears to work.
     
  4. Ugg10

    Ugg10
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    Sorry, should have been clearer. On tge rear of the amp there is an input marked “phono/aux”, this is normally a high level input like all of the rest and not suitable for turntable use. However this amp could be bought with an optional card installed for use with a turntable which takes a the much lower voltages from the turntable cartridge output.

    If you do not have the optional card you phone will play the same through all of the inputs, if it is installed it will be very loud on the one marked “phono/aux” (so when checking out turn the phone volume off and slowly increase).

    The reason for this is that cd, tuner, phones etc. output a signal at around 2V which the amp then increases to a level that can drive the speaker (typically by around 25 times). The cartridge on the turntable only outputs either 5mV for a moving magnet or 0.5mV for a moving coil version which need further amplification to get it firstly up to 2V somthat it can then be increased up to speaker voltage. The phono input also has filtering to take into account pre-emphasis built into the recording and manufacturing of the records.

    So, if you plug a turntable into a normal 2V line level input it will sound very quiet as it is only seeing about 1/400 the signal it is expecting.

    Easiest way to see if you have the phono card is to look through the vents in the top or take the top cover off. If there is a card like the one linked where it says “optional phono card” then you are ok if not you need something like this to boost the signal.

    Project PHONO BOX (Black)

    But first check if you have the optional card, then let us know what cartridge you have on your turntable and we can then go from there.

    Hope this helps.
     

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