Old 05-13-2022, 05:36 AM   #1
nlamont
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Default Faint audio signal from Focusrite 4i4

I tried to do a recording session with a friend today, who was playing very quiet fingerpicking guitar. I tried a few mics going into the Focusrite 4i4 but couldn't get a signal level above-30 at the loudest, and that was with the Gain dial almost at full on, picking up some background noise. I'll detail the setup and what I tried - maybe someone with experience of these devices can help.
Reaper, latest version, Windows 10.
Focusrite Scarlett 4i4

I first tried two dynamic mics, one a Shure SM58. I tried two different cables with them. The mics were about 6-7 inches from the guitar, pointed at the soundhole end of the fretboard. To get any input signal at all, the Gain dial had to be at 4 o'clock at least.

I then tried a Rode NT1 on phantom power. It was slightly better, but the gain still had to be very high - about 2 o'clock, to get a signal of -30.

I looked at the settings in Focusrite Control for Input. I noticed both Inputs were set to Inst. I changed one to Line, but it didn't make any difference.

I don't have this problem with DI instruments or even with vocals, because I sing at quite a high volume. The issue is only with quiet sounds on a mic. But if I had more scope to adjust the Gain it would be useful, instead of having to put it at maximum.

Are there any other settings I should be looking at? Or should I be putting the mic through some sort of pre-amp before the Focusrite?
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Old 05-14-2022, 04:21 AM   #2
JonLinnarson
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Certain dynamic mics like the SM7B often need some sort of mic booster before the pre-amp. If you have high quality pre-amps with 65-70dB+ of gain range (56dB on the 4i4) you might be okay, but even then it's still favourable to use a mic booster when recording quiet vocals or delicate guitar picking.

The SM58/SM57 has a bit louder output than a SM7B, but if your pre-amp isn't that great you might still need a mic booster. The most popular choice is probably the Cloudlifter CL-1. A cheaper (but still great) alternative is the Triton FetHead.

The NT1 should be able to pick up quiet stuff even when using weaker pre-amps.

6-7 inches sounds like it's a bit too close IMO, so if you are not 100% sure how to place and aim the mic for best sound it's a good idea to grab some headphones and use direct monitoring while moving the mic around until you find the best spot. I'll usually start with the mic around 18-20 inches away from the guitar and aimed at the 12th-15th fret, and then I move it closer or further away depending on how the musician is playing (while listening through my headphones).
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Old 05-14-2022, 04:35 AM   #3
bjohn
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Quote:
Originally Posted by nlamont View Post
I looked at the settings in Focusrite Control for Input. I noticed both Inputs were set to Inst. I changed one to Line, but it didn't make any difference.
Is there a setting for Mic? When you're using microphones, the input should be set at mic level, which is different from line or "instrument."
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Old 05-14-2022, 04:54 AM   #4
bjohn
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Looking at the manual for the 4i4, I'm going to guess that you are using cables with 1/4" TRS jacks rather than XLR, which is causing the Focusrite to switch automatically to line level. Line level can easily be 20 dB lower than mic level.

If you use XLR instead the interface will switch automatically to mic level and your problem should be solved. No phantom power needed for your dynamic mics, which you already know. I don't think you'll need a Cloudlifter or anything similar unless the preamps on your Focusrite are really noisy.

Last edited by bjohn; 05-14-2022 at 05:07 AM.
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Old 05-14-2022, 07:45 AM   #5
DVDdoug
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I'm not sure about the Focurite but most interfaces have somewhat-limited gain and they are designed for condenser mics, or a dynamic mic on a snare, or kick drum, or in front of a guitar amplifier, etc.

It's not unusual for people to use the Cloudlifter or similar with dynamic or ribbon mics, or most stand-alone preamps have more gain.

...Just checking specs, the NT1 puts-out 27dB more than the SM57.

Quote:
and that was with the Gain dial almost at full on, picking up some background noise.
Turning-up the gain boosts the signal and noise together so it (usually) doesn't affect the signal-to-noise ratio. It does make the noise more noticeable but it's no different from boosting after recording or during playback.

In other words it doesn't help to turn down the gain unless you can get a hotter signal into the interface/preamp. And it doesn't hurt to turn-up the gain (as long as you're not clipping).

A "hotter" mic doesn't help the acoustic signal-to-noise ratio but it DOES help to overcome preamp noise. Similarly, the Cloudlifter usually has a better signal-to-noise ratio than the preamp so it can help with electrical noise (usually hiss) but again it boosts the acoustic signal and room noise together.
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Old 05-14-2022, 10:25 AM   #6
nlamont
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Quote:
Originally Posted by bjohn View Post
Looking at the manual for the 4i4, I'm going to guess that you are using cables with 1/4" TRS jacks rather than XLR, which is causing the Focusrite to switch automatically to line level. Line level can easily be 20 dB lower than mic level.

If you use XLR instead the interface will switch automatically to mic level and your problem should be solved. No phantom power needed for your dynamic mics, which you already know. I don't think you'll need a Cloudlifter or anything similar unless the preamps on your Focusrite are really noisy.
Thanks but I was using XLR. I didnít know about the difference in volume, however. Even using XLR the signal was too weak.
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Old 05-14-2022, 10:33 AM   #7
nlamont
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Thanks for these replies. Iíd never come across problems very often, and this time it may have been because my friend was very tentative and playing very quietly. Iím going to experiment a bit more with the two types of mic before he comes back. Also mic position, which I rushed a bit. I hope I donít have to buy a mic booster but at least now I know there is such a thing and what it does. Also the explanation of the modes on the Focusrite. Thanks all for sharing your knowledge, itís really helpful.
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Old 05-14-2022, 10:57 AM   #8
bjohn
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Quote:
Originally Posted by nlamont View Post
Thanks but I was using XLR. I didnít know about the difference in volume, however. Even using XLR the signal was too weak.
That's strange. I've never used any Focusrite interfaces, but I use dynamics (including ribbons) on my other interfaces at mic level all the time and get enough clean gain to hit healthy levels (I aim for average of -18dBfs or so). I've never needed an external ribbon preamp or a cloudlifter. I've used SM 57, 58, Beta 58, and some ribbon mics, including on quiet sources. You do have to crank the gain (with ribbons I'm often adding 65 dB of gain), but as long as the preamp is quiet it's not an issue.

From what I read in the Focusrite 4i4 manual, the interface should switch automatically to mic-level input if you use an XLR input (both ends of your cable need to be XLR). If you put a 1/4" TRS jack into the interface it automatically switches to line level. This is common among many interfaces with combi-inputs (XLR and TRS).

You definitely don't want to be recording microphones at line level, they need a preamp. If you plug in an XLR cable the interface automatically switches to mic level and engages the built-in preamp.
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Old 05-14-2022, 11:54 AM   #9
nlamont
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Thanks. Honestly I never knew half of this, I'd just plug in and hope for the best! What you're telling me is really helpful.
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