How to Use Guitar Line M-audio Fast Track Guitar/mic Recording Interface

M-Audio Fast Track questions

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Hi all, apologies in advance for my ignorance but I was hoping someone could help me with a few questions in relation to the m-audio fast track interface that I've had for a while and trying to get my head around.

Does the unit record in stereo at all? I've mainly been plugging my acoustic straight into the guitar input so I'm wondering if the instrument inputs are mono and mic input stereo? I've also only used garageband to record and read that this only records in mono so perhaps this is the issue?

Also, in relation to the mic input, pretty much every mic I've tried to use with the unit only manages to pick up sound if the recording level is maxed out and even then there isn't much volume. Is this due to the unit itself or the mics I've been using? I've tried an sm57 and a number of cheaper of mics with the same result.

Any assistance would be greatly appreciated. Cheers.

I've also read that it's a two-in, two-out interface but I'm not sure what this means.

Lives for gear

Exactly which M-Audio Fast Track do you have? There are many versions, i.e. Fast Track Pro, Fast Track Solo USB-II, Fast Track Duo, etc.

The "Solo" is a 2-in/2-out interface. The 2 inputs consist of 1 XLR mic pre channel and 1high-Z "Instrument" input suitable for a guitar or bass pick-up. Then 2-channels can be routed in a DAW to a single stereo track ,or 2 separate mono tracks, which would be the usual configuration for a Fast Track Solo.

The Solo's two separate inputs are both mono which is the "norm" for most interfaces. A few mixers with internal interfaces have single-jack stereo line-level inputs for their stereo channel strips, but the XLR mic inputs are always mono.

The "Solo" is "stereo" in the sense that it records (2) separate mono channels, but because it does not include 2 mic preamps it can't record a true stereo image of a group of performers using 2 mics or a single stereo mic. It can record a mono mic on one track and a mono guitar on the other.

The Solo's single mic preamp has a maximum gain of only 48 dB which is relatively low. That's enough gain for many phantom-powered condenser mics (which have a relatively high output signal level), but, unless you are recording a very loud sound source like a drum set or an electric guitar cabinet, is not enough for a low-output mic like a SM57 or SM58. For those mics a mic pre with 60 or 65 dB gain is more appropriate.

The Fast Track Pro and the similar Fast Track Duo are also 2-in /2-out interfaces, but include mic pres on both input channels so can record true stereo using 2 mics. The "Fast Track Pro" has a specified gain mic pre gain of "over 40 dB" which technically can mean anything, but probably means it's about the same as the mic pre in the "solo". Again, that's just not enough gain for a mic like a SM57 or SM58 (which normally need a mic pre gain of over 60 dB).

An entry level condenser mic like a AT2020 produces a signal level of -37dBV, while a SM57 is about -56 dBV. Those are negative signal levels, so -56 is much lower than -37). The 19dB difference means the AT2020 produces a signal that is almost 10X louder than a SM57.

There are devices (pre-pre amps) such as the Cloudlifter or Triton Fethead, which can be used to boost the output of a SM57, but you would probably be much better off instead investing in a better interface with higher-gain mic pres, or investing in a more sensitive mic to use with your existing "Fast Track" unit. A low-output mic and a low gain mic pre are not a good match.

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Last edited by Lotus 7; 27th July 2015 at 08:42 AM..

Thanks for all the info. It's starting to make sense now.
As far as I can tell mine is just called a 'Fast Track', but it sounds as though it's the solo that you've described -http://www.proaudiohome.com/image/cache/data/Pro-Audio/Fast-Track-USB-II-Side-600x600.jpg

Looking at the specs for the latest M-Track Plus II for example, what figure should I be focussing on with regard to max gain?

Mic Inputs 1–2 (balanced XLR)
Frequency Response: 20 Hz – 20 kHz (+/-0.1 dB)
Dynamic Range: 104 dB (A-weighted)
Signal-to-Noise Ratio: 104 dB (1 kHz, +1.4 dBu, A-weighted)
THD+N: 0.003% (1 kHz, +2 dBu input, -0.8 dBFS)

Preamp EIN:
-133 dBu (max gain, 40 Ω source, A-weighted)
-126 dBu (max gain, 150 Ω source, unweighted)

Sensitivity: -53 dBu
Gain Range: 55 dB

Lives for gear

Most manufactures simply list a mic pre gain in dB. M Audio lists the input sensitivity and gain range. The "Sensitivity" is the absolute input level that results in a full-scale digital level. In this case it's -53dBu. The "Gain Range" is the amount of adjustment the front panel recording level control has, or in this case a range of settings between -53 dBu maximum gain and +2 dBu at minimum gain. With a sensitivity of -53 dBu, the mic pres in the M-Track Plus II are 5 dB more sensitive then the one in the "Solo". That is better, but is still about 7dB lower than a mic pre that would be best for a low output, SM57 when used with a moderate-level sound source. It might be acceptable with a "loud" sound source and would still need to run at maximum gain.

With a loud sound source of +94 dB SPL , and the gain at maximum a SM 57 will produce a recording level of that is 3 dB below digital "full scale" (expressed as "-3dBfs) That's higher that you need or want to record at. Generally trying for a recording level of around -15 dBfs (in your DAW) works well for tracking if you are assembling a multi-track mix, and you're expecting to add any effects during mixing.

To reach that recording level of -15dBfs (again, with the M-Track Plus II at maximum gain) would take a sound pressure level (SPL) of 82dB SPL. That a loud speaking voice at a few feet away or a moderately-loud acoustic guitar. It might just work, but you would always be running "wide open" unless you were recording loud sources. With an electric guitar cab. or a drum set it would be fine.

Look for a mic pre gain of 60dB or an input sensitivity of -60dBu if you're using a SM57, unless you're only recording "loud" sound sources.

How to Use Guitar Line M-audio Fast Track Guitar/mic Recording Interface

Source: https://gearspace.com/board/newbie-audio-engineering-production-question-zone/1021551-m-audio-fast-track-questions.html

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