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Thread: Phantom Power for Oktava MK-219 Mic

  1. #21
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    Quote Originally Posted by arcaxis View Post
    You woulda' thunk 48 vdc, but......
    48V phantom from PS1A?
    my bad, I was looking up Phantom powersupplies, This one popped up, ad misquote said 48v. Honestly the only ones I've seen are Coil Audio's, in a studio, other than that it was console, or interface.

  2. #22
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    Tried the CAD M179 with the PS400 and as suspected it was stone dead.
    Mark.......

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    Quote Originally Posted by ecc83 View Post
    Whilst it is true that the maximum 10mA draw would only leave 14V on the mic pins any mic manfctr would surely know this? They would therefore be running the electronics as "current source mode" and deriving the polarization voltage from a DC-DC converter. Not forgetting as well that many, quite expensive and decent capacitor mics use electret capsules these days. Then of course, Sennheiser use a completely different principle and need no polarizing voltage.

    Yes, stories abound of ribbons being damaged by phantom power but actual, verifiable incidents are hard to find and of course, SOMETHING has to go wrong, open or short connection for badness to happen.

    I have been told several times that BBC OB trucks used P48 on every XLR and it was not switchable. They used a vast array of mic types including the venerable 4038 and I am sure "steps" would have been taken had even just a few been killed?

    Phantom power is perfectly safe when used correctly and by people who know their job. It is unfortunate now that gear delivering spook juice has fallen easily into the hands of people who do not. However, if those people take the time to learn a tiny bit of electronics theory AND get a frigging meter! Their kit will stay safe.

    Dave.
    Yes Dave, electret capsule mics are self polarised and most Sennheiser condenser mic models do not need polarisation voltage. Some true condenser mics are using DC-DC convertors for capsule polarisation, this case it is possible to calculate and provide right polarisation voltage - if you know taken current from std P48.

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    Hi Mark,

    Thanks for trying that, much appreciated, saved me the bother of getting one and sending it back.

    So how would I know if a unit is capable of suppling the needed amps and voltage. There's 2 more cost effective options here:

    Millenium Pocket Phantom – Thomann UK
    Millenium PP2B Phantom Power Supply – Thomann UK

    Is it just a case of contacting the supplier?

    No point paying any more than this as might as well get a new condenser that will work with the 24V from the Mic Mechanice

    Cheers

    Masten

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    Quote Originally Posted by Masten View Post
    Hi Mark,

    Thanks for trying that, much appreciated, saved me the bother of getting one and sending it back.

    So how would I know if a unit is capable of suppling the needed amps and voltage. There's 2 more cost effective options here:

    Millenium Pocket Phantom – Thomann UK
    Millenium PP2B Phantom Power Supply – Thomann UK

    Is it just a case of contacting the supplier?

    No point paying any more than this as might as well get a new condenser that will work with the 24V from the Mic Mechanice

    Cheers

    Masten
    You can't know if they won't tell you. Bloody silly because it is the primary purpose that phantom PSU supplies the right currents and voltages and with minimal noise (and most people buy a separate PSU BECAUSE they have a mic that needs more than the usual 2-3mA! and bus powered AIs often fail to deliver)

    I suggest you order the one you most fancy and if you can, include a note saying "I presume this supply can supply the standard 10mA maximum?" If it does not when delivered take advantage of the Distance Trading Regs and bounce the bugger back!

    Dave.

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    Quote Originally Posted by ecc83 View Post
    You can't know if they won't tell you. Bloody silly because it is the primary purpose that phantom PSU supplies the right currents and voltages and with minimal noise (and most people buy a separate PSU BECAUSE they have a mic that needs more than the usual 2-3mA! and bus powered AIs often fail to deliver)

    I suggest you order the one you most fancy and if you can, include a note saying "I presume this supply can supply the standard 10mA maximum?" If it does not when delivered take advantage of the Distance Trading Regs and bounce the bugger back!

    Dave.
    Std Phantom P48 has stabilised (or multi-filtered) +48V DC BEFORE 6.81k resistors, and after them (because of them) voltage at mic XLR becomes current depending. And low <15V phantom is "normal" if consumed current is 10mA! Mics must be right designed (and most case are) to be compatible with voltage dependance of current they consume.
    But if you are connecting such mic to non-std, more stable +48V DC Phantom (voltage less depending of consumed current), you can get a problem (to high polarisation voltage - sticking of membrane etc.).
    Most external Phantom PSUs are made std way, no difference are you using internal or external Phantom source. Except mixers with WEAK Phantom power supply - if you are connecting several mics/DI-boxes consuming high Phantom power, Phantom voltage is even more reduced (or even 48V stabiliser can go out of regime), and it results in distortion, hum and even not working at all mics. No damage, but bad results.

  7. #27
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    Quote Originally Posted by Ainaudio View Post
    Std Phantom P48 has stabilised (or multi-filtered) +48V DC BEFORE 6.81k resistors, and after them (because of them) voltage at mic XLR becomes current depending. And low <15V phantom is "normal" if consumed current is 10mA! Mics must be right designed (and most case are) to be compatible with voltage dependance of current they consume.
    But if you are connecting such mic to non-std, more stable +48V DC Phantom (voltage less depending of consumed current), you can get a problem (to high polarisation voltage - sticking of membrane etc.).
    Most external Phantom PSUs are made std way, no difference are you using internal or external Phantom source. Except mixers with WEAK Phantom power supply - if you are connecting several mics/DI-boxes consuming high Phantom power, Phantom voltage is even more reduced (or even 48V stabiliser can go out of regime), and it results in distortion, hum and even not working at all mics. No damage, but bad results.
    Yes, you are preaching to the converted! The problem is, some of the phantom power units do NOT have stabilized 48V supplies BEFORE the 6k8s! Thus these units deliver a lower voltage to the microphone than they should for modest current demands and some collapse altogether if more than 4 or 5 mA is demanded. The same is true of some bus powered AIs.

    This situation is unacceptable. DC-DC converters are cheap and readily available (there are millions employed in AIs) and in my experience well regulated. The rubbish PSU I bought (ITA) used a crude "diode pump" circuit and was nowhere near specification.

    The vendors of these supplies should make that specification very obvious.

    Dave.

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    Ok thanks everybody for the help, saved me a lot of bother messing about trying to get stuff to work. Seems mad to me that they make phantom power supplies that cant generate enough current for my mic but there you go. I'm probably gonna try another way to sort the problem

    Masten :)

  9. #29
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    Quote Originally Posted by Masten View Post
    Ok thanks everybody for the help, saved me a lot of bother messing about trying to get stuff to work. Seems mad to me that they make phantom power supplies that cant generate enough current for my mic but there you go. I'm probably gonna try another way to sort the problem

    Masten
    Hey Masten,
    I'm coming back to this thread because I'm not sure the test I did with the Cad M179 was a good one. Evidently my M179 had a accumulated a significant amount of moisture in the case or being brought out into the room which was somewhat humid that day. I'm not sure if this skewed the current it was pulling and thus didn't work with the Behringer PS400 supply. It subsequently had a total failure and didn't work on any preamp I plugged it into. Tried drying it with desiccant packs and no luck. I'm suspecting the 60 volt bias on the capsule leaked across it due to moisture and took out the FET OpAmps in the front end as those seem to have issue of the high current draw. Won't know for sure until I get the replacements I ordered and plug one in.

    The Behringer PS400 may have worked, but not 100% sure.
    Mark.......

  10. #30
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    Hi Mark,

    Right. Ok well thanks very much for trying it anyway. Did you get the replacement and manage to try it with the PS400?

    Cheers

    Masten

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