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Me: I'm running Logic Pro X, I've been using Garage band and I just upgraded. I have 2 issues out the gate that I cannot seem to get around. My Focusrite Scarlett 2i4 is reading my SM57 when it's plugged in but it's not outputting on Logic. I can see in my logic that it's picking up the signal and in the interface that it's picking up, but I cannot hear what's going in. The S, R, and the I are all clicked, The output is set to Scarlett 24i and the input is too in the logic audio preferences. Interestingly when it records the SM57 it shows that something is being recorded but on playback nothing plays. Gain is up on the focusrite, headphones are plugged in, I don't get output on headphones or without headphones. I've only tried listening through my laptop headphone jack. Guitars plugged in through this same set up do actually produce an output. Just neither of my microphones will produce an output. The other microphone my AT2035 will however not work at all. Even on Garageband where I can get the SM57 to at least generate an output. The AT2035 just has not recorded any sound. I have the 48v button pushed on and I still can't get input or output from it. Anyway I'm really knew so I would love to figure out what I'm doing wrong. Thank you.


dvdhawk Sun, 01/12/2020 - 21:22

Initial thoughts:

Is the switch that corresponds to the mic's channel set to "Line"?
Is the "Pad" button disengaged?

You're right, the 48v has to be engaged for the AT2035 to function.

With the "Direct Monitor" knob turned to the 12 o'clock position and the Headphone Level up you should hear the mic in the headphones independent of any Logic settings.

If not, you may have a bad mic cable or (less likely) the mic has gone bad.

redcat Mon, 01/13/2020 - 12:36

Boswell, post: 463140, member: 29034 wrote: Phantom power (48V) is only available on the XLR pins of a microphone input. Check that you are using an XLR- XLR cable and not an XLR - jack plug.

Okay I think this is closer to the right answer. I'm using an XLR-1/4 inch jack to go into my focusrite. My SM57 works like that, but my XLR-XLR cable does not plug into a my interface(?)
Do you have a link to the type of cable I should be using?

Boswell Tue, 01/14/2020 - 10:11

redcat, post: 463169, member: 51821 wrote: what does earth lead mean? I’m kinda new to this lol.

It's the use of a separate single, insulated, stranded piece of wire with its ends bared (insulation removed) to make an independent connection to earth. One end of the wire is taken to an earthing point on the equipment (or trapped under the head of a screw on the metal chassis), and the other end taken to an earthing clamp round a water pipe or similar supply that comes into the property via an underground duct. This must not be a gas pipe.

Here in the UK we have strict regulations about mains earthing, so, even though the single phase and three-phase property voltages are 240V and 440V respectively, there is generally not a huge problem. However, I know from posts on this and other forums that the situation in the US can vary enormously, both in State regulations and also enforcement.

That all goes out of the window if equipment such as a laptop power supply runs from a 2-pin mains lead and a USB audio interface is connected and powered by the laptop. Add to that the observation that most laptop power supplies are built to the minimum that meets the radio interference emission standards and not for good earthing, and you have a mixture that can give you the sort of problems you are reporting.

One thing to try is the suggestion that Dave Hawk made, and that is to run the laptop and interface from the laptop battery, not connected to the mains. You only need a couple of minutes to see if the problem is still there when you remove the mains connection.

dvdhawk Tue, 01/14/2020 - 11:01

He mentioned Garageband, so I'm asssuming he's running a macbook and I've never come across one with a noisy power supply. Anything is possible of course.

Boswell, how well do the Scarlett's combo jacks cope with global 48v phantom power when there's a 1/4" TS in one and a condenser mic in the other using the XLR? Is it safe to assume there is additional circuitry to keep the 1/4" TS from shorting out the 48v, given the way they share contacts?

Boswell Tue, 01/14/2020 - 15:17

dvdhawk, post: 463171, member: 36047 wrote: well do the Scarlett's combo jacks cope with global 48v phantom power when there's a 1/4" TS in one and a condenser mic in the other using the XLR? Is it safe to assume there is additional circuitry to keep the 1/4" TS from shorting out the 48v, given the way they share contacts?

Yes, definitely.

PP is applied from a 48V power source to pins 2 and 3 of an XLR connector through 6K8 resistors. These limit the current available, and the usual design convention is that short-circuiting the two signal pins of any one XLR input to ground should not materially affect the PP at the other sockets.

The second point is that, in a pre-amp that can supply PP, the XLR and TRS inputs are never connected directly together (pin2 to tip, pin 3 to ring), even if the two inputs have the same sensitivity and hence gain. Either transformers or blocking capacitors are used to keep the high potentials out of the TRS circuits, usually backed up by a normalling arrangement on the jack terminals.

It's more common that jack inputs have a lower sensitivity than XLR inputs, and this is achieved either with an attenuation circuit feeding the input stage, or by routing the TRS input signals so they join in after the first gain stage of the pre-amp. This latter case completely avoids any PP conflict at the microphone connector.

One of my many portable recorders is an M-Audio Microtrack II. This is the only piece of (semi) pro gear I know that supplies its 48V PP through the same 1/4" TRS jacks as its line inputs. I have to use XLR-TRS microphone cables, and be really careful to switch the PP on at the start and then off at the end of the gig only while the TRS plug is in the socket. That caveat apart, it's a surprisingly capable piece of gear.