Focusrite Scarlett 8i6 and 18i6 Review

Mike Rivers

© September 2011

Revised October 2011 (latency settings vs. computer performance)

USB audio interfaces have been with us for quite some time now. They’re popular for several reasons: There’s no need to install a host card in the computer (a real benefit to laptop users), they’re less expensive than similar

Firewire devices, just about every computer has a USB port, and for the most part they just work. But with only a few exceptions, USB audio interfaces are designed around the USB 1.1 rather than the much faster USB 2.0. This is largely because most versions of Windows include a class-compliant driver for stereo audio I/O over USB 1.1 which means that the hardware manufacturers, as long as they design around the Microsoft driver, need not write a device-specific driver. Apple Core Audio includes a similar built-in driver that supports USB 2.0.

A few USB 1.1 interfaces offer more than two channels in and/or out, including

Focusrite’s own Saffire 6 USB. TASCAM was a pioneer here with the elegant

US-428 developed in partnership with Frontier Design. Pushing the USB 1.1 bandwidth limit, it offered six simultaneous audio streams at 44.1 kHz configured as four inputs and two outputs for playback and monitoring during overdubbing.

The US-428 required a proprietary driver to support both audio I/O and its handson control surface which was not universally compatible, either among computers or software – a great idea which was abandoned too soon.

For one reason or another, USB 2.0 audio interfaces were slow out of the starting gate, and USB 3.0 for audio has yet to be explored. Edirol (a Roland division, now under the Cakewalk brand name) was early, perhaps first on the scene with a multi-channel USB 2.0 audio interface, providing an alternative to the sometimes cranky Firewire interfaces that were filling that need. With more manufacturers seeing Firewire fading into the sunset, the USB 2.0 audio business is starting to pick, with more companies having solid experience designing these products (TASCAM, RME, and let’s not forget Focusrite) jumping onto the USB 2.0 bandwagon. Having “upgraded” to a portable computer with no means of Firewire support, I’ve been eager to check out a one of these new breed of multi-channel audio interfaces, so here it goes.

Meet The Scarletts

From a distance, the Focusrite Scarlett 8i6 and 18i6 look like siblings, but they’re about as alike as two pumpkins in a patch. The most obvious difference is in the number and flavor of inputs and outputs, but there are other differences beyond

“bigger must be better” that may suggest which one is better for your applications. The model numbers refer respectively to the number of inputs and

outputs, but as is typical with model numbering systems like this, you have to know what you’re counting.

Inputs

2 front panel mic/line/instrument

Combo jacks

18i6

Outputs

2 rear panel line (TRS)

Inputs

2 front panel

Combo jacks

8i6 mic/line/instrument

Outputs

4 rear panel line (TRS) &

Front panel stereo

6 rear panel line TRS jacks

2 S/PDIF

(RCA) headphone

8 ADAT Optical

(TOSLINK)

Front panel stereo

(same as Line outputs 3-4)

2 S/PDIF (1 RCA) headphone

(counts as 2)

2 rear panel line TRS jacks

2 S/PDIF

(1 RCA)

2 S/PDIF (1 RCA) 2 Loop Back

Counting the ins and outs of the 18i6 is pretty straightforward, but the 8i6 is a bit confusing. The front panel headphone jack carries the same audio as Line

Outputs 3-4 on the rear panel. Then there’s the Loop Back. The manual describes it as an input (which would bump the input count properly up to 8), but it actually functions as an output. More about this later.

Both are housed in a steel case, 8¼” wide x 7½” deep x 1¾” high, making it kind of a tight squeeze for a single rack space mounting, but I doubt they were intended for that. Four soft stick-on feet are provided for tabletop use. The front panel is scarlet-red plastic finished and sculpted to look like anodized aluminum, with light gray lettering which I wish was a little larger and a little whiter for better contrast. Could be my old, tired eyes, but I had a difficult time reading the panel legends in both the studio control room in an auditorium when for some live sessions. Fortunately, there isn’t much to read.

Internal construction looks clean and solid. Most components are surface mounted and the circuit boards are pretty crowded, suggesting that these units won’t be easy to repair. Although all circuit boards are different between the two units, the basic layout is the same - a main board and three front panel boards

(Combo jacks, pots and LEDs, and headphone jack). Rear panel connectors are all attached to the main circuit board. The Scarletts use Cirrus Logic CS4272

24-bit codec (A/D and D/A converter). This is a high performance mid-range component, an excellent choice for an interface in this price range. The CS4272 is capable of supporting 192 kHz sample rate, though the Scarletts top out at

96 kHz.

Like the Focusrite Saffire Firewire interfaces, the Scarletts use a computer application, Mix Control, to control many of the functions. I’ll cover it detail in a bit, but it’s worth mentioning a couple of things here. First, like the Saffires, the application is based around a DSP mixer which provides very low latency input

monitoring. Unlike the Saffire series which is based on hardware DSP for mixing, and hence once set up, can stand alone without a computer connection, the

Scarletts leave some that that heavy lifting to the host computer. You can’t get any sound out of them without the USB connection.

Update –

I discovered purely by accident that the 8i6 does indeed pass audio from the front panel inputs to

A proprietary USB2 driver for Windows XP and Vista

(32-bit only) and 32- and 64-bit Windows 7. On the

Mac side, the Scarletts are supported by the Core

Audio driver in OS-X 10.6 (Snow Leopard), with Lion support recently announced. Though the Mac doesn’t require a special driver, it’s necessary to install Mix the monitor and headphone outputs, without a USB connection.

Maybe this came with a firmware update or perhaps it always worked this way. This means that it can function as a standalone mic preamp! In

Control.

The Scarletts require more current than the 500 mA allowed by the USB device powering specification so they must be powered externally. The package includes a 12 Vdc 1250 mA switching wall wart that connects to the unit with a common 5.5 x 2 mm nonlatching coaxial plug. It’s not my favorite type of connector and I can’t resist making snide remarks about the risk of the unit coming unplugged, but addition, if you set up a mix when connected to the computer then pull the

USB cable (or shut down the computer), it’ll retain that mix. However after cycling power, be a plain stereo preamp. Not a bad bonus, though.

The 18i6 works a little differently in this “broken” honestly, I’ve never had one pull out unexpectedly.

The front panel layout of the two models is similar - two XLR-TRS Combo mic/line/instrument jacks, each having its own gain control. A phantom power switch with an LED indicator applies power to both XLRs. state. It continues to pass audio with the established mix if the USB connection is broken, however, once power is removed and restored, it’s dead until it sees the driver.

The Monitor (rear panel Line outputs 1-2) and ¼” front panel headphone jack each have their own volume control. There are no controls on the rear, nor is there a power switch (boo hoo, bah humbug!).

A group of three status LEDs indicate power, USB connection, and that the unit’s data clock is locked to a reference, either the internal clock, incoming S/PDIF data stream, or, for the 18i6, the incoming ADAT data stream. Selection of the clock sync source as well as switching the front panel ¼” input jacks between

Line and Instrument is software-controlled via the Mix Control panel. An LED for each of the front panel inputs indicates when it’s in the Instrument mode. Line or mic input characteristics are determined by whether you plug into the XLR (mic) or TRS (line or instrument) part of the connector.

Front panel metering is the bare minimum. The green “signal present” LED indicates a digital recording level of –18 dBFS, while the red “clip” LED indicates

0 dBFS. There’s a lot of guesswork as to the actual level between the two indications, so it’s important to have a computer nearby to view the meters either in Mix Control or your DAW. The level indicators are adjacent to the front panel input gain controls on the 8i6, however there are no level indicators for the rear panel line inputs. The 18i6 has eight pairs of LEDs in a block for monitoring the levels of the two front and six rear analog inputs. There are no front panel level indicators for the S/PDIF or ADAT optical inputs, on the assumption that these inputs come from A/D converters with their own input metering. All of the digital input levels are, however, metered by the Mix Control panel.

Moving around to the back, you’ll clearly see the differences in the available inputs and outputs to the right of center.

8i6 Rear

18i6 Rear

A quick glance suggests that the 8i6 is suitable for basic tracking chores – a pair of mics or a mic and an instrument pickup plugged into the front, maybe a keyboard plugged into the back, and that’s it. But the four line outputs (in addition

to the front panel headphone jack) suggests an independent headphone mix or two (depending if you want mono or stereo) for musicians in the studio. The 18i6 has fewer outputs but more inputs, suggesting that it’s more appropriate for live recording applications. With the addition of an 8-channel mic preamp with ADAT optical output and a stereo preamp with S/PDIF output, you really have 18 mic inputs, enough to track a decent sized band with multiple mics on the drums.

Gozinta and Gozouta Tech

The built-in mic preamps in both models are clean and quiet, what’s usually described as “transparent” or “uncolored.”. Quiescent noise level is -86 dBFS

RMS at maximum gain and with the input terminated in 150Ω (typical source impedance for a microphone), At maximum gain, -42 dBu at the mic input is required to reach maximum record level. This isn’t a huge amount of gain, so you may find yourself running at or near full gain for quiet instruments or a quiet speaking voice even when allowing a reasonable amount of headroom. Speaking about 6 inches from an SM57 with the gain set to maximum produced a recording with peaks reaching about -18 dBFS, which will look pretty wimpy on your DAW’s track waveform graphic display. The preamps and A/D converters are sufficiently quiet so you needn’t be afraid of adding gain in mixing or post production if you need it. Incidentally, those figures are very close to what I measured for the Saffire Liquid 56, so the preamp circuitry may be identical to the higher priced Firewire-connected series.

There’s no input pad switch, but at minimum gain, the mic inputs will take

+8 dBu before clipping so there should be no problem with screaming singers or heavy handed drummers. Input impedance is 3.0 kΩ, a good match for nearly any modern microphone. Phantom power is a little shy at 42.6 volts, just barely out of the IEC tolerance of 48 v ±10% but it should power any but the most fussy mics. Correct audio polarity is maintained throughout, with a positive sound pressure against the mic diaphragm producing a positive-going peak in the recording, which plays back as a positive peak at the line output.

As with the Liquid Saffire 56, the gain control is kind of fiddly through the top

20 dB or so of its range. This is a fairly common annoyance in modern project studio gear because there’s just nobody making pots with the proper taper

(resistance vs. rotation) to give a smooth gain adjustment throughout the control’s full range. To illustrate this graphically, here’s what the gain knob would look like if calibrated in dB of attenuation rather than from 0-10. The marketing spiel is that it’s easy to adjust gain accurately in the range where it’s most likely to be used, but not all of us record the same sources and in the same way.

The ¼” front panel line/instrument DI inputs are also identical on the two models.

As line inputs, the gain control covers the range of -19 dBu to +30 dBu for 0 dBFS which will cover nearly anything from consumer gear like MP3 players to the speaker output of a guitar amplifier. Input impedance is 42 kΩ balanced

(between tip and ring), or 21 kΩ between tip and sleeve when connected to an unbalanced source. In the instrument DI mode, the gain range is the same as the mic input, clipping at +8 dBu at minimum gain and -42 dBu at minimum gain. This is a pretty hot DI input and you may need to run the Scarlett at minimum gain or turn down the volume at your instrument if it has particularly hot pickups. Like the line inputs, the instrument inputs are also differential, with each leg having an input impedance of approximately 500 kΩ. It’s rare that a guitar is wired to take advantage of a differential input but it’s a nice touch. The only possible disadvantage is with unbuffered piezoelectric pickups that are happiest working into an input impedance of 1 megohm or greater.

The rear panel line inputs are a mixed bag. On the 18i6, all six are fixed gain.

The 8i6 offers a choice of high or low gain for the two rear inputs via a switch on the Mix Control panel. At low gain, +16 dBu in = 0 dBFS, and at high gain, -6 dBu in = 0 dBFS. Input impedance is 17 kΩ at low gain and 25 kΩ at high gain.

Furthermore, the 8i6 inputs don’t have the identical input impedance on each leg so they may not give the fully expected common mode rejection when fed from a balanced source. In each case, the tip is the higher impedance, about 10 kΩ at low gain and 20 kΩ at high gain, making the high gain input practically unbalanced. This is probably OK in practice since the high gain range is appropriate for consumer devices which generally have single-ended outputs.

Also, we’re talking about high level sources here, not microphones, so the inequality of input impedance on the two legs shouldn’t really present a problem.

I’m only mentioning it because I measured it, so someone else probably will, too.

The story is a little different on the 18i6. All of the rear panel line inputs are fixed gain, but surprisingly, all inputs are not all identical. All hit 0 dBFS at +10 dBu in, about midway between the high and low gain settings of the 8i6, but input impedances differ. Inputs 3 - 6 are, like those on the 8i6, 18 kΩ tip-to-ring, and somewhat unbalanced, with the impedance from tip to sleeve being close to

11 kΩ. Inputs 7 and 8, while having the same gain as 3 - 6, are fairly accurately balanced, with the input impedance of the two legs being 8.2 and 8.3 kΩ. In a world where maximum output levels for studio gear such as outboard mic preamps tend to run in the range of +18 to +24 dBu, I think that a fixed maximum input level of +10 dBu might be a bit too sensitive. If you have a beloved vintage mic preamp that you want to connect to the 18i6, be prepared to throttle its output down a bit.

Maximum output level from the balanced line level Monitor output jacks on the rear of the 18i6 with the mixer’s meters indicating full scale is +16 dBu. This should be sufficient to drive most powered monitors to full volume. A passive

speaker system with a power amplifier that has fixed input sensitivity, however, may or may not make it to full SPL. The Monitor level control on the front panel is always active, though there’s a secondary monitor level control in the Mix Control which can enabled to allow monitor volume to be controlled from the computer.

More about this later.

The maximum line level output from the 816 is lower, +11 dBu at full scale mixer level. I needed full gain on my monitor amplifier in order to get the front panel

Monitor volume control into a comfortable working range. I suspect that the 8i6 was tailored more to the nominal input level of powered computer speakers than professional studio monitors. This is reasonable since some of the other characteristics of the 8i6 tend to favor the needs of the single user desktop studio. I’m not suggesting that this is in any way undesirable. Those guys and gals (and you might be one yourself) can and do turn out professional work too.

At maximum mixer output and with the headphone volume control set so that total harmonic distortion (THD) remained below 1%. the 8i6 headphone output measured 43 milliwatts into a 70 Ω load (Sony MDR-7506 phones). It starts to get nasty as you go louder than that, reaching 16% THD at maximum output, which is only 2 dB above the 1% THD level. The 18i6 is a little cleaner and a little hotter, putting out 110 mW at less than 0.1% THD. On both models, THD started to climb rapidly with the headphone volume control turned beyond about 3 o’clock. Cranking the 18i6 up full way adds only about 1 dB of headphone level, but at 7% THD. Both are plenty loud, though since it’s possible to clip the headphone amplifier, watch your ears.

There isn’t much to say about the S/PDIF and ADAT optical ports. There’s

S/PDIF input and output (RCA jacks), but ADAT optical is input only. The S/PDIF input works with sample rates up to 96 kHz, but above 48 kHz sample rate, the

ADAT input carries only four channels rather than eight. This is a limitation of the

ADAT specification, not the 18i6. Two niceties that are lacking here are a second

TOSLINK connector to allow S/Mux mode with 8 channels and making the

TOSLINK input switchable between ADAT and S/PDIF optical. The TOSLINK socket has a spring-loaded “doggie door” to keep dust off the optical sensor when the cable is unplugged.

There’s also MIDI In and MIDI Out ports. Not much to say about them other than that they work. If you have a MIDI keyboard, this gives you a way to connect it.

I did all of my testing at 44.1 kHz sample rate because that’s how I do most of my recording, though I checked it out at 96 kHz and verified that the high frequency response is indeed extended and it’s flat out to a bit beyond 40 kHz at 2x sample rates. Distortion figures are, as expected, too low to worry about other than where the distortion products lie in the frequency spectrum, and I don’t have the proper test equipment to show that, nor would I worry about it in a product in this price range unless there’s something odd about the sound, which there isn’t.

Mix Control

Mix Control is the software application that comes along with the Scarlett interfaces (and with Focusrite’s other multichannel audio interfaces, for that matter). It has two major functions - to provide multiple low latency mixes of the audio inputs and playback of DAW tracks, and to control signal routing, switching functions, and setup options for the hardware. Since input and output configurations of the two Scarletts are different, some of the details you’ll see when you dig into Mix Control will be a little different, but functionally they’re very much alike. Here’s the Mix Control screen for the 18i6:

There are six mix output streams available. These can be configured as six independent mono mixes, three independent stereo mixes, or some of each as in the above screen shot. For most applications, you can think of it as a mixer with a main stereo output and four auxiliary outputs which can be linked as stereo pairs when needed. The tabs across the top select which mix is displayed.

It’s a pretty rudimentary mixer with just level and pan controls for each channel – no EQ, no compression, no reverb. There’s a high resolution meter for each channel which gives you a quick picture of your levels, though there’s no calibration scale for the meters. Mid scale is –20 dBFS, so as long as your eyeball average level is in the top half of the scale, you’ll have a reasonable record level with adequate headroom. A red Clip indicator turns on and sticks when a channel hits 0 dBFS. The maximum level for the channel as well as the gain setting of the fader is indicated in tiny numbers at the bottom of the meter.

Clicking on the channel’s Clip indicator resets it as well as the indicated maximum level. Clicking the clip indicator above the output meter resets all the

channel clip indicators. Ctrl-clicking on the Pan slider centers it, Ctrl-clicking on the fader sets it to unity gain.

The row directly below the mix tabs serves as a virtual input patchbay. Clicking on the box above an input fader brings up a menu to select the

8i6 inputs channel’s input source. Channel sources can be either hardware inputs or returns from the DAW.

Once an input source is selected for a mixer channel, it’s grayed out. Adjacent channels can

18i6 inputs be linked as a stereo pair by clicking on the button below the fader. When channels are linked, one of the two faders disappears, the pan slider becomes a balance control, and the meter displays the channel levels as two adjacent bars. As with a hardware mixer, when you (virtually) connect an input to a channel strip, that same input is available in six mixes. You can’t, for example, assign Analog in 1 to

Channel 1 in Mix 1 and Analog in 4 to Channel 1 in Mix 2.

The rightmost fader is the master, and the box above it selects the output to which that mix is assigned. Like the inputs, the outputs are selected from a drop-down list. Like inputs, outputs can be either mono or linked for stereo. Each mix output can have multiple

18i6 outputs destinations. For example, you can send the same mix to both the control room monitors

8i6 outputs and the front panel headphone jack by selecting both Mon 1-2 and Line H/P L-R as the output destination. If a single output is selected, that name is displayed above the output fader. If more than one destination is selected, “Many” is displayed above the fader. You can assign a mix to several outputs, but you can’t assign more than one mix to any output.

When you stare at the output lists long enough, you realize that they’re not quite as flexible as they might be. For example, while looking at jacks, you’d think (as I did initially) that the 8i16 had four line level outputs as well as the headphone output, however, that’s not the case. The headphone jack carries the same signal as Line Outputs 3-4. If you want a stereo mix from Line 1-2 for the control room monitors and want to use another mix as a reverb send, you can do that, but then you lose the headphones (or rather, plug in the headphones and you’ll hear the reverb send). For studio work, I’d prefer to have the headphone jack carry the same signal as the monitors, leaving the other two outputs for other chores. On the other hand, as it is, for overdubbing, you can create a “more me” mix in the headphones without disturbing your well balanced mix for playbacks. In the 18i6, you don’t have that option to wish for since there are no rear panel line level outputs corresponding to the headphone outputs.

A neat Mix Control feature is the “Copy to Mix” button above the main fader. This allows you to copy all of the fader and pan settings of one mix to another mix. For example, once you get a good mix going on the control room monitors, you can use it as a starter for your studio headphone mix, then tweak it, rather than starting from scratch, to make the players happy. I really appreciated this feature when I reviewed the Liquid Saffire 56 which has a lot more outputs than the

Scarletts, but even with just a couple of studio mixes, Copy to Mix can save time.

Each input channel has a Mute, Solo, and PFL button. Mute is obvious. Solo is a

“destructive mute” post-fader and post-pan, which mutes everything but the soloed channel. This is often called “Solo in place.” PFL is a pre-pan and prefader solo, affecting only the Monitor (Line 1-2) output. It does this by temporarily re-routing the selected channel directly to the Monitor outputs, replacing the mix that’s normally assigned to those outputs. Solo only works in the headphones if you’re soloing a channel in a mix that’s assigned to the headphones. The PFLs are “radio buttons” – you can’t have two inputs selected at once. You can, however, monitor duets or trios by pressing as many Solo buttons as you desire.

It took me a little head scratching to catch on to this when I had one mix assigned to the control room monitors and another mix assigned to the S/PDIF output which was feeding both a CD recorder and the headphones. I was listening to the recording mix on headphones and wanted to solo a channel, but since Solo is destructive, it also soloed the channel on the recording, which is obviously undesirable. So I thought “Oh! I’ll just switch to the Control Room mix, add the

Headphones to that mix, and then I can solo channels without affecting the mix going to the CD recorder. But then when I returned to monitoring the CD mix, it was gone from the headphones since it only allowed me to assign one mix to the

Headphone output. If I ever figure a way around this, I’ll amend this review. My best solution was to assign the main mix output to the headphones

One thing that’s kind of clever about solos is that there’s a Solo button on the main output faders. What it does is switches the Monitor outputs from your normal control room mix to the mix you’re looking at. If you want to make an adjustment to a studio headphone mix, select that mixer’s tab and you can hear the headphone mix by clicking on its main fader’s Solo button. These buttons are momentary, not latching like the other Solo buttons, so you’ll return to your normal control room mix when you release the button.

The lower portion of the Mix Control screen is devoted to direct routing, monitor control, and some setup options. Here, the two models differ slightly.

18i6 Mix Control Routing and Control Section

The Routing section selects and indicates the source for the Monitor outputs, the

Headphone outputs, and the S/PDIF outputs. Clicking on any of the source buttons, for example [Mx 1(L)] brings up a pull-down list of Inputs, DAW returns, or Mixes. The above screen shot shows that Mix 1 is routed to the Monitor outputs (which normally feed the control room speakers) and also the headphones. Nothing is being sent to the S/PDIF outputs. These buttons interact with the destination selections for the various mixes, but they give you some additional monitoring options. For example, if you have a stereo pair of ambience mics on inputs 7 and 8 of an 8-channel ADAT output mic preamp and wanted to listen to those mics in the headphones, you could bypass the mixer and route

ADAT 7 and ADAT 8 directly to the headphones. This is a shortcut to opening the mix that goes to the headphones and pressing the PFL button for the linked mic pair. You’ll notice that when you select PFL on any channel, the source for the

Monitor outputs switches to the channel you’ve selected.

The Routing Preset button pops up a short list of setups that Focusrite thinks might be useful. Clear removes all output assignments. DAW Tracking (when you’re using the DAW’s mixer rather than the Scarlett mixer for your monitor mix) assigns DAW output streams 1 and 2 to the Monitor and Headphone outputs.

Zero Latency Tracking assigns Mix 1 to the Monitor and Headphone outputs.

The bottom row of switches change the front panel ¼” jacks from Line to

Instrument DI input. Switching to Inst illuminates the Inst LED on the front panel.

The knob in the lower right, along with the four buttons above it, controls the volume of the Monitor and Headphone outputs. This control comes ahead of the front panel Monitor and Headphone knobs so those knobs remain active at all times. Clicking on the buttons above the volume knob toggles them between blue

(knob active) and red (output off). Shift-clicking the buttons (gray) fixes the output going to the front panel pots to level where the knob is set when you clicked. If you want to control the volume from the computer rather than the front panel, clicking on the gray button turns it blue, making the software knob active again.

The four buttons below the knob selectively mute the left and right channels of the monitor, mute both channels, or reduce the monitor output level by 20 dB while you answer that important phone call.

Sample rate, can be set from a pull-down menu in the setup section of the Mix

Control panel, but it also follows the DAW project settings. These units have no

word clock input so when using the analog inputs, Internal sync is the way to go.

The Scarlett can synchronize its internal word clock to an incoming S/PDIF or

ADAT data stream, and it’s necessary to do so in order to avoid clicks in the recording when using either digital input.

What if you’re using both the ADAT and S/PDIF inputs? That’s when you need to hope your digital sources have the proper set of word clock connections to synchronize one to the other. Then you can synchronize the Scarlett to either one. I tried this using a Mackie 1200F (S/PDIF output) and a Mackie 800R

(ADAT output). The 800R has only a word clock input, so I used the word clock out of the 1200F to synchronize the 800R, then set the Scarlett to sync to the

ADAT input. By golly, inputs from both recorded click-free. Sync Status tells you that the internal clock is synchronized to whatever source you’re selected, while the USB Driver status tells you that you have a valid USB connection. The sync and USB connection status indicators are duplicated on the front panel.

The device name (8i6 or 18i6) appears below the status/sync group. The manual says you can customize this (“Mike’s Scarlett” for example). I couldn’t get it to work, but pardon me while I digress a bit. The Saffire series interfaces, subject to the limitation in the number of streams that can squeeze through the Firewire interface chip, can be cascaded for more inputs and outputs. When you connect two of them to the same computer, a little arrow appears next to the device name, telling you that there’s a pull-down menu. Opening the menu shows you both device names, and here you can select which one you want displayed in the

Mix Control panel. Curiosity got the best of me and I tried connecting both the 8i6 and 18i6 to see if they, too, were supported in the same way as the Saffire series. The driver gets as far as putting the little arrow next to the device name, but neither the second device nor its mixer shows up. Perhaps this is leftover code from the Saffire version, or maybe it’s a hint that a future firmware update will support more than one Scarlett talking to the ASIO driver. Now back to your regular program.

The Settings button has only one selection, ASIO buffer size. Rather than displaying the selections in number of samples, it displays the buffer size in milliseconds, ranging from 1 to 20. I don’t know if there was a driver change with which the 18i6 manual (the web download, which I assume is most current) hadn’t caught up, but according to that manual, there are two settings, one for the ASIO buffer and another for a USB buffer. This may be a case of a bit of text re-use from the Saffire manual (which has settings for ASIO and Firewire buffers) that didn’t get edited, or a predictor of things to come. The 8i6 manual shows what you see in Mix Control. The default ASIO buffer setting is 10 ms, and that’s where I left it until I started playing with latency.

The bottom section of the 8i6 differs slightly from the 18i6. The direct routing buttons are the functionally the same except that the 8i6 screen adds rear panel

Outputs 3 and 4 which the 18i6 doesn’t have. The two models actually have the

same number of analog output streams (four), but on the 8i6, Outputs 3 and 4 feed both the headphone jack and the rear panel line output jacks 3 and 4.

8i6 Mix Control Routing and Control Section

The 8i6 has one pair of outputs and their corresponding router buttons that are conspicuously absent on the 18i6. These are the

Loop Back outputs. The name isn’t very descriptive, but what they do is make a mix available for use by another program. One practical use for this to record the monitor mix to a stereo pair of

DAW tracks during a tracking or overdubbing session. This is often a convenient way to send the artist home with a quick mix of the day’s work for evaluation. For podcasting, you could use the mixer to control your various program sources, assign the mix outputs to the Loop Back outputs, then use the Loop Back as the source for the program that streams your program on the Internet.

The screen shot at the right shows how the Loop Back outputs look to Sound

Forge’s Audio Device Preferences setup.

In deference to the manual’s description of using Loop Back to record audio streaming over the Internet, by assigning the Scarlett as the Windows default audio playback device, the incoming audio stream from, say, an Internet music program, shows up in Mix Control as

DAW 1 and 2. Assign the output of a mix with DAW 1 and 2 as input channels to

Loop Back 1 and 2 and the Internet stream indeed becomes available to a recording program.

Along the bottom row of the Mix Control panel are switches to select Line or

Instrument level for the two front panel jacks, same as on the 18i6. The other two switches in that block select the gain range for the two rear panel Line inputs. On the 18i6, the gain of the rear panel Line inputs is fixed, hence no switches.

One gripe that I have with Mix Control, and it’s been the same since I reviewed the Focusrite Pro26 io and Pro10 io several years back, is that its window isn’t

sizeable (at least that’s the case with the Windows version) and it takes up a good bit of screen real estate. On my little netbook computer (1024 x 600 pixels) it occupies the full screen, in fact I need to make the Windows task bar at the bottom of the screen disappear so I can get to the Settings button. When working with the Scarletts on the netbook, I was constantly having to minimize and expand the mixer display.

Even on my studio computer with a 22” wide screen monitor, it was always in the way. I don’t normally run with dual monitors, but for test purposes I borrowed a second monitor from another system and found that for what I was doing, it was much more convenient to give Mix Control a screen of its own, leaving the other screen free for the DAW. But in retrospect, I was mostly using it in a review environment where I was constantly wanting to look at the mixer screen. In an actual working situation, I opened Mix Control, set things up, got a workable monitor mix going (most often one or two mics and DAW playback which I was mixing in the computer anyway) and then minimize the Mix Control display and ignore it for a while.

Latency

There are two distinct, independent, and significant latencies that we can observe. First is input monitor latency signal path through the Scarlett’s “Zero

Latency” mixer. The input signal goes directly from A/D converter to the mixer, and out through the D/A converter to the headphones or control room speakers.

The time between input and output isn’t zero, but it’s darn close, an impressive

0.6 milliseconds at 44.1 kHz, half that at 96 kHz. The only other interface I’ve encountered that’s on par with the Scarlett is Focusrite’s Saffire. The ASIO buffer size has no effect on this latency, not surprising as the monitor mix is done with hardware DSP within the interface and this audio path doesn’t pass through the computer at all.

DAW monitor latency, however, is a different story. Here, the signal passes through the computer before it gets to the DSP mixer. This is the latency that most influences the response time of a virtual instrument played through the interface, or the delay for which you’ll need to compensate by sliding overdubbed tracks into time alignment if your DAW program doesn’t to it for you. Here, the

ASIO buffer setting is indeed significant. At the 10 ms (installed default) setting which I’d been using for testing and straightforward audio recording where record-play latency is irrelevant, it takes a healthy 52 ms from the input source to reach the output. Setting the ASIO buffer to 2 ms yielded a It’s a more reasonable 12 ms latency, and with a 1 ms buffer, the latency was a perfectly respectable 7 ms. I expected this to be more computer-dependent, but I measured exactly the same latency with the 3 GHz Pentium 4 in the studio and the 1.3 GHz Pentium Mobile laptop.

Of course whether it’s possible to record successfully with 1 ms ASIO latency will be a function of your computer, how many tracks, and what processing plug-ins you’re using, if any. I didn’t push it, but let it record a single stereo track for half an hour at the 1 ms on the laptop without a crackle. Then I moved to the studio started overdubbing stereo tracks. I checked the playback after each overdub, and got bored after four overdubs after not hearing any crackles or glitches. This was at 44.1 kHz sample rate, on a 3 GHz Pentium 4 with 2 GB RAM, running

Windows XP Service Pack 3. You’re bound to find a performance limit, but all in all this is good performance for a low cost portable recording or desktop production device.

Here are the graphic results of my latency measurements for 2, 4 and 10 ms

ASIO buffer setting respectively. The upper track of the pair is the input pulse.

The first pulse on the lower track is from the input monitor, and the later pulse

(the one marked on the time line) is the monitor return from the DAW. Obviously in session you won’t have both of these active on the same track (you’ll hear your input source echoed if you do) but it makes an interesting comparison.

Scarlett Monitor Latency for 2, 4, and 10 ms ASIO buffer settings

In Use

I never thought I would need an instruction manual for a wall wart power supply, but I’ll admit that I was a bit puzzled when I opened the box and saw a plug that didn’t fit a common US outlet. (A web search indicated that this plug was common in the UK, Hong

Kong, and Singapore.) The clue that maybe they didn’t send me a unit destined for another country was that there were a couple of alternate plugs in the package, but I had to study it for a while before I discovered the button that released (with some difficulty) the outlet adapter and allowed me to slip on the

US version. So here’s the missing wall wart instruction manual. It’s truly a worldwide power supply accommodating 50-60 Hz, 100-240 Vac input.

Software installation went smoothly. Though it didn’t follow the prompts and responses exactly as in the manual, if you’ve ever installed new hardware for a

Windows computer, you’ll know what to do – run the installer, plug in the interface, let Windows find the driver you just installed, and that’s it. There’s a CD with the installer packed with the unit as well as a note recommending a visit to the web site for the latest installer version. Windows installs drivers for ASIO,

WDM, and MIDI, as well as the Mix Control, on a Mac, only the Mix Control is installed.

After beating up the Scarletts in the shop for a couple of weeks and concluding that they sound just fine and recording was reliable, it was time to start putting them to use with a real project.

My first trial run (which, fortunately, was a dry run) was the kind of application that originally attracted me to these units. I occasionally do live sound for acoustic string bands, small classical, and jazz groups who request a recording of the performance, which hopefully, is good enough to release. Depending on the program, either I’ll record a mix from the PA console or, if the group is well balanced and the room acoustics are good, record au naturel using a stereo mic.

Either way, my go-to “professional” portable recorder for the past few years has been a Korg MR-1000 which records stereo to an internal hard disk. It has decent preamps with XLR inputs and phantom power as well as balanced line level inputs, making the recording rig simple and compact.

There have been times when I’ve wished I could record both the stereo mic and the console mix, choosing one or the other or a mix of both when in a better listening environment. I don’t own a compact 4-channel recorder but I had hoped to make one by using the Scarlett 8i6 with the small Toshiba netbook computer that I carry when I travel. The computer has only an 1.6 GHz Atom N450 CPU

and 1 GB of RAM under the hood, but I’ve recorded 8-track projects successfully using computers with less horsepower, so I expected this to be a breeze.

Unfortunately, it wasn’t. When using

Reaper, which is a pretty efficient

DAW program, sometimes I could get a successful two-track recording, sometimes a successful four-track recording, but all too frequently, even a mono recording would be plagued with clicks. Further, when using Sound Forge with this computer and either Scarlett, although everything appeared to function properly, when it came to actually rolling “tape,” this combination would neither record nor play. More often than not, the program would run for a second or two and just grind to a halt with

Sound Forge no longer recognizing the Focusrite USB driver.

Since both programs worked fine with the Scarletts on other computers, I could only conclude that there was some incompatibility issue with the netbook that I wasn’t able to resolve easily. Some computers just don’t cooperate with audio devices and this seems to be a particularly unhappy combination.

I’ve recorded stereo successfully with this netbook using its built-in sound card or a USB 1.1 interface but neither Scarlett could be counted on to work with it.

I’ve done the basic “optimize your

Windows computer for audio” tricks, and perhaps if I spent enough time with it, I’d eventually get the Scarlett and the netbook working reliably, but

Update and a Mea Culpa–October 2011

Focusrite was in a bit of a hurry to get these units back so I didn’t spend too much time fussing with the netbook since my disappointing initial results were quite inconsistent, from trial to trial and for the two units.

Just as I was about to pack up the units and ship them back, Tech Support e-mailed me a link to a new beta driver, Mix Control, and firmware update bundle to try. I loaded it up in hopes that it would solve all, or at least some of my problems. It appeared to solve a few, but at first try with the netbook, I still couldn’t get a satisfactory recording or playback every time.

With this update installed, I experimented further with buffer size even though the crackling, stalling, and poor recording when it worked at all sounded more like a clock issue than insufficient buffering. While I was working on this review, increasing buffer size helped neither recording nor playback with the netbook. This time around I discovered that with a sufficiently large buffer, I could consistently play a properly recorded file. If

I decreased the buffer size, I could make it sound grungy, or even halt playback entirely. And with the buffer set large enough so a file would play cleanly, I was also able to record cleanly and consistently.

Using an hour-long four track recording as a test, the 18i6 performed satisfactory with the buffer set to 6 ms or greater. Curiously, the 8i6 required at least 10 ms of buffering in order to work reliably.

Throwing all caution to the wind, I set the buffer to 10 ms and recorded two continuous hours of eight tracks glitch-free using the 18i6, Reaper,

Windows XP, and a flea-powered computer.

I don’t know if this success story is a result of the driver update or if I just never used a large enough buffer initially (if so, mea culpa), however, the bottom line is that I now feel confident that I can use this compact rig for multitrack capture. A large buffer is of course of no consequence for live recording, which is the purpose for which I had hoped to use this setup, so I’m a happy boy.

I’m not sure. There were things about this problem that sounded more like a clock sync problem than something grabbing too much computer time even though the Sync Status never indicated anything but “Locked.”

Since I had a live show coming up and I really wanted to put a portable computer-based recording rig under fire, I set the netbook aside and went back to the old reliable IBM T-42 Thinkpad laptop.

Using the Scarlett 8i6 with the Thinkpad, the session went off without a hitch, so at least I’ve proved the concept. Recordings with the Scarlett and the Korg recorder (you didn’t think I’d go without a backup do you?) sound pretty much alike, so, to be honest, for a stereo gig, I’d opt for the simpler setup of the Korg and leave the computer at home. Back in the shop, I pushed the Thinkpad to record 8 tracks (44.1 kHz, 24-bit) with no problems using the 18i6 with a generous ASIO buffer size, demonstrating that this combination would work well for recording direct outputs from the PA console should the occasion arise.

Back in the studio, I used the 18i6 for a couple of string band sessions. Since I needed more than two mics, I expanded it with a Mackie Onyx 800R 8-channel mic preamp through the ADAT port and a Great River MP-2H into a pair of analog line inputs. While the preamps all sound a bit different, the Scarlett’s preamps stood up against the others very nicely. One Scarlett preamp got a vocal and the other got a mandolin, pretty much a random choice.

For this type of music, a single headphone mix usually works for everyone in the band who wanted to wear phones (some often don’t), so I used stereo Mix 1 to feed the control room monitors, then fed the Scarlett’s headphone jack with

Stereo Mix 2. The 18i6 headphone output fed band’s headphones through a four output headphone amplifier. After getting a reasonably balanced control room mix, I used the handy “Copy to Mix” feature to set up the band’s mix, then tweaked it a bit to their liking. I got some “Can you take some of the treble off my fiddle in the earphones please?” but that’s something that can’t be adjusted in

Mix Control. Fortunately, the headphone amplifier has a bass and treble controls for each output, and that made them happy.

Having only one stereo headphone mix for the studio, however, took me back about 25 years. I could get two independent mono headphone mixes with the

18i6 by splitting the headphone jack outputs and assigning one mono band mix to Phones Left and another to Phones Right. I didn’t need to do that for this session, but I verified that with a little creative patching, it’s a workable solution.

Alternatively, since the control room mix and the studio headphone mix, at least for this session, were pretty close, if someone really wanted a different stereo headphone mix, I could have split the control room mix to the studio phones as I used to do years ago, then used the headphone jack for the oddball mix.

The 8i6 with its two mic, two line, and stereo S/PDIF inputs would have been a bit cramped for this session but it would have worked since we ended up not using more than 6 mics in any pass. To get to the last two of those six inputs, however, requires a mic preamp with S/PDIF output (which I don’t have) or an outboard stereo A/D converter (which I do). That’s getting to be quite a stack of boxes and haywire, though, OK in the studio in a pinch, but I wouldn’t like it for my regular field recording rig.

Computer Foibles

I was a little puzzled that when I started a new 96 kHz project in Reaper or

Sound Forge after previously recording at 44.1 kHz, Mix Control didn’t show that the Scarlett had switched to 96 kHz. After some experimenting, I found that it was actually recording at the sample rate set by the project just as it should, but that it was necessary to close and re-open

Mix Control in order to get the correct

Update – sample rate displayed. Since most of us don’t switch sample rates all that frequently, I

The issue of the sample rate not following what’s set in the DAW expect that most users won’t encounter this project has at least partially been issue. Since it appears, at least on the fixed with the Mix Control update surface to be a communication problem that I received just before returning between Mix Control and the hardware, the review units. I could see the hopefully a driver update will fix it. sample rate box change from 44.1 kHz when opening a new project

One thing I encountered while bashing at 96 kHz, but it was still necessary to close and open the around in the studio with either of the two

Scarletts was that every now and then, although the interface was still passing audio,

Mix Control seemed to get lost. The meters

(you can do this without interrupting a recording or playback) and re-opening it

Mix Control panel to see a change to a lower ample rate. They’re on the right track with this one, though.

After this update, I didn’t encounter would stop responding and moving a fader didn’t change the mix. Closing Mix Control the loss of control from Mix Control that I had observed during a long session, and this was specifically one of the problems which this brought Mix Control back to life. This was a pretty rare occurrence and I couldn’t trace it to anything I was doing. One thing that might update addressed. On occasion, however, the Scarlett would not be recognized if it was powered up with USB connected before the have aggravated this was that while I was comparing the two units, I was switching computer was ready to go. between them as quickly as I could, without rebooting the computer. Sometimes

Mix Control wouldn’t respond after switching interfaces until I powered down the interface and powered it up again.

I checked with Focusrite Tech Support and, since what I described sounded like something they had observed themselves and were working to fix, they pointed me to a beta version of the driver to try. The new driver didn’t seem to change

anything, however, I found a start-up sequence that worked flawlessly once the computer was booted up:

• Close Mix control if it’s open

• Connect the USB cable

• Apply power to the Scarlett

• Open Mix Control

Once I settled into that start-up sequence, Mix Control always was alive and saw the interface when it was opened. If you turn everything in your studio on with a single master power switch, as long as the Scarlett is connected and powered before the computer finishes booting, it will always be ready to go.

I did a lot of things while wringing out these interfaces that a normal user probably wouldn’t do, including the unthinkable (or at least unadvisable), recording to an external USB hard drive with the Scarlett and disk drive connected to the computer through the same hub. It recorded 16 tracks for 2 hours straight and it was stable and I didn’t detect any glitches. The new driver, however, did nothing to reduce the clicks and crackles with the netbook computer, nor did I really expect it to.

With the Thinkpad, Mix Control would consistently get lost with the Scarlett and an external hard drive connected to the computer’s two USB ports. Recording never crashed, suggesting that the driver was still working normally, but after a couple of hours, Mix Control’s meters would stop metering, the faders would stop fading, and the status panel (though not the front panel LED) showed that USB was disconnected. Closing and re-opening Mix Control would revive it. This is something that Focusrite said they, too, had observed when there was activity on the USB controller other than the Scarlett interface, and that they were working on it.

While this quirk was somewhat annoying, it wasn’t a killer problem. Getting the screen display back to normal took only a couple of mouse clicks and there was no interruption to the recording. I expect that eventually there will be a Mix

Control or firmware update that will resolve it. Since I’ve seen a few comments on forums describing what might be the same behavior, I thought it was only fair to give you a heads-up and a ”don’t panic” in case it happens to you.

Docs

The Scarlett manuals are on the disk that’s packed in the box. They’re also available for downloaded from the Focusrite web site. They’re a bit sketchy but cover the important points. There’s a bit of text re-use from the Saffire manuals,

(or maybe some features that didn’t make it to this version of the Scarlett) that might be misleading. For example, the Loop Back (an 8i6 feature only) is

described as an input in the manual which offers the capability to record streaming audio from a media player or web browser. In reality, it’s not an input, it’s an output which appears as an audio device to your DAW. You can indeed record an Internet audio stream but It takes a little head scratching to get your gozintas and gozoutas straight.

Freebies

Most audio I/O hardware comes bundled with some useful software, and the

Scarletts are no exception. Both include the Focusrite Scarlett plug-in suite consisting of VST, RTAS, and AU versions of a reverb, compressor, gate, and

EQ. These appear to be the same as those that are bundled with the Saffire series, but with a red skin rather than blue. They work, they sound fine, and they’re likely to be a little different from, and maybe even better than similar tools you might already own. The only thing wrong with having too many plug-ins is that you might spend too much time deciding which one to choose.

But wait! There’s more! The package also includes the Focusrite Excite+ bundle consisting of Abelton Live Lite, a recording and loop-based production DAW,

Novation’s Bass Station bass soft synth, plus a gigabyte of royalty-free samples from Loopmasters to get you started doing what Live does best.

Conclusions

These are very nice units. They sound very good and there’s no reason to be worry that, due to the low cost, your sound quality might be compromised. Some users are wary (or suspicious) of the need to turn a control nearly full up, as you might need to do with the monitor volume or input gain. This is really nothing to worry about, and it’s common with a lot of products in this class. It goes along with designing a cost-effective product to meet the functional needs of smaller scale users. All other things being as good as they need to be, there’s no reason why you can’t make a high quality recording with either of the Scarletts.

Which one is right for you? Count your input and output requirements, but know what you’re counting, and don’t forget to allow for growth.

The 8i6 is basically a stereo in/out box with benefits, but a lot of benefits. Its six inputs gives you a fair amount of flexibility. For example, its two mic inputs can be easily expanded to four with an outboard stereo preamp, then two more with a preamp that has S/PDIF output (or a separate A/D converter). You get two clean high impedance instrument DIs and the four analog line level inputs will handle your guitars and keyboards. While the four output streams will primarily be used for the control room speakers and the front panel headphone jack, they’re available for multiple monitor mixes during tracking.

The Scarlett 8i6 can hold its own nicely for desktop production projects, but it can also serve as the centerpiece of a small studio by accessorizing it with a multichannel headphone amplifier and maybe a couple of outboard mic preamps.

One thing that you might wish for if you’re producing audio for video or games (or just playing games) is another couple of analog outputs for 5.1 surround monitoring. As a reminder (or if you just skipped ahead to this part of the review), while there are six physical analog counting the headphone jack, phones receives the same signal as the Line Output 3 and 4 jacks. But don’t forget the

S/PDIF outputs, which can provide the other two channels. You’ll need either an outboard D/A converter or powered speakers with an S/PDIF input (which aren’t so uncommon these days).

The 18i6 has the same output setup as the 8i6 with the exception that it’s shy one pair of rear panel output jacks to make room for the additional input jacks.

For 5.1 surround monitoring, you’ll need to use the S/PDIF output like with the

8i6, but you’ll also need to feed one pair of speakers from the headphone jack.

No big deal, just a little uglier as far as cabling. I’m not faulting the Scarletts here, just pointing out what to expect if you need surround monitoring.

Where the 18i6 stands out is in its greater input capability. With the two front panel mic/line/instrument inputs, six more analog line level inputs, and ten digital inputs (ADAT Optical and S/PDIF) and the right collection of outboards, you can do a live multitrack recording of a pretty good sized band.

I’ll reiterate here that the Scarletts require a computer connection in order to pass audio. Of the three Windows computers I used with this review, one had no problems at all, one worked fine for audio but Mix Control was a little quirky, and the third was nearly a total dud. I didn’t test it with a Mac or with Windows 7 one of which I expect will be the system of choice for most users. Those are probably the systems that got the most testing before release, and are probably the first to be attacked by Focusrite’s good technical support should problems arise, so your chances of smooth sailing with a modern computer are pretty good. Windows 7 support has been there from the get-go and support for Apple’s latest Lion operating system has recently been validated.

With street prices around $300 for the 18i6 and $250 for the 8i6 it seems like the extra fifty bucks for ten more inputs (whether you need them now or not) would make the 18i6 the wise choice. The only thing that you lose, along with the fifty bucks, is a pair of output jacks on the back and the input sensitivity for the rear analog inputs. As far as I can tell, there’s no performance premium paid for the additional inputs other than more work for the computer if you use them. The only measurement tools I have for computer load are Windows’ and Reaper’s performance meters, and I could see no significant difference in the numbers between the two when recording four channels.

If you’re a soloist working from your desktop, go for the 8i6 and put the $50 you save toward a great microphone. If you’re a podcaster or work-at-home broadcaster or producer using several different analog sources (CD players, turntables, mics, maybe a sampler) in your regular work, then the 18i6 might be the better choice. Alternatively, you might prefer the flexibility of an analog mixer as the control center for your studio, in which case the 8i6 may be sufficient.

However, for live multitrack recording, particularly if you’re clever with racking and cabling so you won’t have an armful of loose boxes to stack up and connect when working in the field, the 18i6 won’t disappoint you.

Pros:

• Nice clean preamps that work well with any mic

• Very low latency input monitoring

• Separate and independent jacks for mic and line inputs (good for fixed installations)

• Nice bonus plug-ins

Cons:

• Skimpy front panel metering, no scale on Mix Control meters

• Gain pots are touchy near the top end of the range

• No inserts between analog inputs and A/D converters

• You’ll need an assortment of analog and digital sources to take advantage of all of the inputs and outputs.

Street price: Scarlett 8i6 - $250

Scarlett 18i6 - $300

Further Information at: http://focusrite.com/products/audio_interfaces/scarlett_8i6/ http://focusrite.com/products/audio_interfaces/scarlett_18i6/

Focusrite Novation Inc.

840 Apollo Street, Suite 312, El Segundo, CA 90245

TEL: (310) 322-5500

Bonus Track - Coming Soon

Just as I was finishing up this review, Focusrite announced the Scarlett 2i2. This is a straightforward 2 input and 2 output USB 2 recording interface that appears to have the same guts as the other Scarletts but with without the Mix Control software application. A single pushbutton engages direct input monitoring (zero or low latency, depending on whether the routing is analog or digital), and with all necessary controls located on the front panel. Powering is from the computer’s

USB port. The 2i2 is already being advertised for as low as $150. Maybe it’s all you need when you really don’t need much but want Focusrite’s great audio quality.