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Small waveforms from mic input. Problem?

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Small waveforms from mic input. Problem?

Postby KMPLSV » Thu Aug 06, 2020 7:57 am

My current signal chain is: Rode NT1-A -> WA12 pre-amp -(via line input to bypass Saffire pre-amp)--> Focusrite Saffire Pro 14 -> MacBook Pro w/ Reaper. My issue is that the signal is coming in super hot. Even with no gain, it is too hot. It basically goes from silent to clipping with any adjustment at all. I've experimented a bit with using the "PAD" button on the WA12 and it does help, but the resulting waveforms are very small. I'm going to crank the gain up further and test it out again. However, if they continue to come out small, is it a "safe" practice to use "shift + up arrow" on them to increase peak height? Will this cause any issues down the road with production/mixing? I want to be sure it isn't just artificially patching a bigger issue. I'm also going to try taking the WA12 out of the equation and running the Focusrite straight to my MacBook, although I kind of wanted to use the WA12 pre-amps. I've been told it's really a wash and there won't be any noticeable difference between the WA12 and the built-in pre-amps. Between this kind of issue and the absolutely horrid headphone output (starts distorting horribly if volume is turned up past 6) on this Focusrite, I can't wait for MOTU M4 units to get in stock so I can replace this thing! :-) Any help will be much appreciated.


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Re: Small waveforms from mic input. Problem?

Postby CS70 » Thu Aug 06, 2020 10:05 am

KMPLSV wrote:My current signal chain is: Rode NT1-A -> WA12 pre-amp -(via line input to bypass Saffire pre-amp)--> Focusrite Saffire Pro 14 -> MacBook Pro w/ Reaper. My issue is that the signal is coming in super hot. Even with no gain, it is too hot.

You have to plug the output of the WA12 in the line input, not connect the Røde to the WA12 line input. The WA12 is the preamplifier.

So mic -> WA12 mic input -> Saffire line input -> ...
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Re: Small waveforms from mic input. Problem?

Postby CS70 » Thu Aug 06, 2020 10:10 am

To help you understand why: the mic produces a tiny signal (a voltage) which is called "mic level".

A preamplifier takes this one and carefully amplifies it to a higher voltage ("line level") which, being more beefy, is then much easier to handle with low noise and distortion by components downstream.

The WA12 is a preamplifier. The Saffire has preamplifiers as well. You've got to chose which one to use. If you want the WA12, you connect the mic to the WA12 mic input, resulting in a line signal, which goes into the Saffire line input.

The WA12 has a line input because it can be used as a color box besides a preamplifier.

If you want to use the Saffire to preamplify, you connect the microphone to the saffire mic input, resulting in a line signal, and then you can use the WA12 to "color" the signal by plugging the line output from the saffire into the WA12 line input.

All this said, when you're doing it right you will see tiny waveforms in the DAW. Read my post here to understand why :)
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Re: Small waveforms from mic input. Problem?

Postby Hugh Robjohns » Thu Aug 06, 2020 10:30 am

CS70 wrote:You have to plug the output of the WA12 in the line input, not connect the Røde to the WA12 line input.

Pretty sure that's what the OP is doing. I think it was just slightly confusing grammar... Try this:

KMPLSV wrote:My current signal chain is: Rode NT1-A -> WA12 pre-amp -> Focusrite Saffire Pro 14 (via line input to bypass Saffire pre-amp) -> MacBook Pro w/ Reaper.


This problem is just basic gain-staging.

First, make sure in the Saffire Mix Control that you have the line inputs set to LOW GAIN. That will configure the inputs for peaks to +16dBu instead of -6dBu (-10dBV). To be honest, both are a bit low for a professional gear, but the +16dBu mode should be workable if you set the input gain on the WA12 sensibly.

If you have the WA12 mk 2 it has an output level control that you can use to back off the output level a bit to keep the Saffire happy. If it's the mk 1, then you just have to set the WA12's gain control at a sensible level, in combination with the input pad switch if working with loud sources and close miking.

Small waveform displays are more a frustration than a problem, and most DAWs have a method to enlarge them... What's important is the actual recording level. Aim for levels to average around -20dBFS with peaks around -10dBFS and absolutely no higher than -6dBFS. That gives you sensible headroom margins which makes the plugins sound better, the analogue monitor signal sound better, and gives you space to record and mix without worrying about clipping -- in the old-school analogue way!

This article gain staging article might help.
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Re: Small waveforms from mic input. Problem?

Postby James Perrett » Thu Aug 06, 2020 2:42 pm

With Reaper you need to go to Options->Peaks display mode->Scale peaks by square root. That will give you a better view of levels which relates more closely to the way that your ears hear level.
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