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Old 11-15-2020, 12:50 PM
Darryl Ramm Darryl Ramm is offline
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Join Date: Nov 2010
Location: USA
Posts: 19,657
Default Re: Low input Signal

Quote:
Originally Posted by rosella84 View Post
I checked the phantom power with a multimeter. Pin 1 and 2 showed 50.5 and the same for 1 and 3. Could it be a problem that there is too much phantom power?
That phantom voltage is fine. Great you checked that. The super anal-retentive next thing to do would be to measure the voltage under the very slight load of a mic... very likely a waste of time to do that and you need to undo the back of the XLR connector if you wanted to. That's more likely checking for a damage mic power circuit than a damaged phantom power source.

While you have a multimeter use the resistance/continuity mode to check the XLR cable to make sure the pins are connected straight through and there is no break in the cable or signal wires shorted to ground/shield (either one of the signal wire being disconnected or shorted to ground/shield will about halve the signal level). But if it’s the exact same cable you can switch back in and test on the mixer with the mic then you can be pretty sure it works OK. But do that now... if the feeling here is the Mic has reduced its sensitivity a lot then maybe it was damaged, dropped etc. between using on the mixer and the interface.

It may be the mic is just low-sensitivity (in general... I will look up the specs later... or this specific one) and your mixer has a higher gain preamp, the preamp on the Mbox are not particularly high gain.

Or it could be that the Mbox preamp is just faulty and not producing as much gain as it should (around 60dB??... there might be a spec somewhere). You can do some crude measurements of the gain by outputting a very low level signal on one of the line level outputs (use signal gen with a sine wave at 1 kHz) but the exact instructions depend on how the Mbox implements stuff (esp. if you connect a signal into the TRS line level input... does the mic gain knob still affect the level seen in the Pro Tools input meter?). Let me know if you want to go down that rat hole.

Last edited by Darryl Ramm; 11-15-2020 at 02:43 PM.
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