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Line Level Technical Question

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Comments

  • #32
    ZENER
    Registered Users, Registered Users 2 Posts: 6,166 ✭✭✭ZENER


    253884.png

    Hopefully this makes sense to you. IT's the simplest way of achieving the changeover from Main to Standby without involving Relays or switches.

    I had thought about using the REMOTE out from the head. This would work while the system is powered on - disconnecting the Main supply - but I don't think it will wake the system up because there probably won't be any output available with the Main PSU disconnected.

    The diodes in this circuit shouldn't cost anymore than 40 or 50 cent each. Probably cheaper if you use 1N4001 which can carry 1 amp but as I'm not sure what the standby current requirements are for the DSP and Head-Unit the 1N5401 (5 amp) are probably safer.

    Let me know if there's anything else I can do or if you need any clarification on the circuit.

    Cheers.

    Ken


  • #33
    crosstownk
    Registered Users, Registered Users 2 Posts: 12,863 ✭✭✭✭crosstownk


    ZENER wrote: »
    Could you try something for me ? With the main PSU turned off and the standby PSU on can you check if the REMOTE out from the Tuner has any voltage on it when you try to turn it on ?

    Ken

    No voltage from the REM with main PSU off.

    Many thanks for the diagram. Another visit to Maplins.......
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  • #34
    crosstownk
    Registered Users, Registered Users 2 Posts: 12,863 ✭✭✭✭crosstownk


    I'll resurrect this thread rather than start a new one.

    I've had this system up and running for over six months now. As far as I'm concerned it the dogs dangly bits. Crisp, clear sound, lots of volume and full of raw energy. I'm happy out with how it sounds.

    However, I do have one problem.

    What I'd like to do is connect my home stereo to the home adapted car set up. I have connected the 'rec out' of my Pioneer receiver to the aux in on the Pioneer head unit. Yes, the audio works well but I've got the dreaded ground loop. If I use my iPod or iPhone I have perfect source but once I connect either to their 220VAC charger then the 50Hz ground loop returns. The same happens if I connect the Pioneer receiver or any of the sources - turntable, keyboard, computer, etc - anything that's plugged into the mains will give me the 50Hz buzz.

    I could always disconnect the ground to the PSU but that has potentially hazardous implications. Or, I could try a ground loop isolator such as this.

    Obviously it's a difference in ground potential between my grounded PSU and my ungrounded receiver/iPhone/iPod/anything connected to mains but will the isolator cure my woes?

    Is an iPhone 5 charger and iPod (dock connector) grounded or ungrounded?
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  • #35
    ZENER
    Registered Users, Registered Users 2 Posts: 6,166 ✭✭✭ZENER


    What is your current grounding setup on the system ? Do any of the components have a connection to Earth or is it simply the PSU (-) terminal ? Does the large PSU have a bridge to connect the (-) terminal to Earth as an option ?

    Also worth checking if the Phono sockets on the components are connected to the chassis of that component. Some car stuff uses floating grounds. You can check simply with a Multimeter on continuity mode, one probe on the Phono ground (with no connections plugged in) and the other probe on the chassis.

    The isolator should do the trick but inductive components will damage the sound quality - attenuation of the high frequencies and poorly defined lows are symptoms of cheaper types.

    A more expensive opto-isolator type would avoid this. If the Pioneer Receiver can accommodate all your mains powered devices - Turntable. PC output, iPod Dock and has an optical output then maybe this might work ? You could power this unit from the main 12V PSU via a small 5V Regulator like a 7805 so you don't end up at square one when using the supplied PSU ?

    Ken


  • #36
    crosstownk
    Registered Users, Registered Users 2 Posts: 12,863 ✭✭✭✭crosstownk


    Hi Ken. Thanks for the reply.

    Just to be clear, this is a multi amp setup and the 50Hz buzz is present in all amps which is why I think it's a ground loop problem.

    I carried out the continuity test on the mid and low amps. The mid amp (4ch) has continuity between phono gnd and all (+&-) speaker connections (weird?) but no continuity between phono gnd and chassis or -12VDC. The low amp has no continuity between phono gnd and anything - except phono out which is not used in this application.

    As the components are 12VDC neg ground, the only connection to household earth is the PSU via the 220VAC plug. The receiver has no ground at the 220VAC plug nor does the turntable or keyboard. I cant vouch for the iPod charger connections (standard equipment from Apple - not a dock) but I reckon they have no earth.

    I can use the iPhone/iPad/iPod on battery so that's not a problem. With the keyboard I could take a hit in SQ due to the isolators BUT I'd sooner have no SQ loss with the turntable.

    EDIT: No optical out on the receiver.
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  • #37
    Fuzzy Clam
    Closed Accounts Posts: 3,293 ✭✭✭Fuzzy Clam


    Just for sake of it, try earthing any of the suspect equipment. i.e the receiver or turntable.


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