As promised over in Annyloggy...
The specification for phantom power is that it should deliver up to 10mA total current from the two "legs".
This does NOT mean you will measure 48V with a 10mA load. To test 48V you will need..
1) Voltmeter (with resistance measurement if possible i.e. almost any $30+ DMM)
2) Two 6,800 (aka 6k8) 1% resistors*
3) XLR 3 male plug
4) Soldering kit.
The 6k8s are soldered to pins 2 and 3 of the plug and the other ends both go to pin one. Leave the wires full length.
Plug into mixer, tape, whatever and clip meter across a 6k8. Power up. You should read 24volts across the resistor. If so this indicates that the circuit can deliver at least 7.6mA and that is enough for almost any capacitor microphone.
Now clip meter across pins 2 and 3. Ideally zero but a few mV indicates the lack of matching of the internal 6k8s (but see *) . Poor matching here will reduce PSU noise rejection but is rarely a problem.
If you wanted to check for the full 10mA you need a 1k4 load (2x 2k8) when you would get 14V across it but I doubt any modern mic would need anything close to ten mills?
*Buy a rake of resistors, cheap enough! Go through them and find the best match. Does not matter if they are "off" 6k8 a bit (you can use Ohms law to check the error but spook juice really is not that critical) what matters is that they are as close in value as possible.
Dave.
The specification for phantom power is that it should deliver up to 10mA total current from the two "legs".
This does NOT mean you will measure 48V with a 10mA load. To test 48V you will need..
1) Voltmeter (with resistance measurement if possible i.e. almost any $30+ DMM)
2) Two 6,800 (aka 6k8) 1% resistors*
3) XLR 3 male plug
4) Soldering kit.
The 6k8s are soldered to pins 2 and 3 of the plug and the other ends both go to pin one. Leave the wires full length.
Plug into mixer, tape, whatever and clip meter across a 6k8. Power up. You should read 24volts across the resistor. If so this indicates that the circuit can deliver at least 7.6mA and that is enough for almost any capacitor microphone.
Now clip meter across pins 2 and 3. Ideally zero but a few mV indicates the lack of matching of the internal 6k8s (but see *) . Poor matching here will reduce PSU noise rejection but is rarely a problem.
If you wanted to check for the full 10mA you need a 1k4 load (2x 2k8) when you would get 14V across it but I doubt any modern mic would need anything close to ten mills?
*Buy a rake of resistors, cheap enough! Go through them and find the best match. Does not matter if they are "off" 6k8 a bit (you can use Ohms law to check the error but spook juice really is not that critical) what matters is that they are as close in value as possible.
Dave.
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