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  • Focusrite Pro 24 DSP Audio Interface with VRM - Now with Conclusions

    Interfaces are a popular topic for pro reviews, but Focusrite’s Pro 24 DSP FireWire interface offers an interesting twist – their VRM (Virtual Reference Modeling) technology. Don’t know what it is? You will by the end of reading this review.

    In a nutshell, the Pro 24 DSP models a variety of typical listening rooms and scenarios, from living room televisions to pro studio speakers. If you’re the type of person whose process of judging mixes involves listening to the mix over multiple speaker systems, VRM is intended to basically provide that option for you - virtually. This is also obviously relevant for those who do laptop work away from a main studio, not just because of the VRM technology but also because this is a relatively portable interface – it measures 8-1/4” wide, 7-5/8” deep (not including protruding knobs or the jack collars on the back), and 1-3/4” high.

    Focusrite has a particularly complete <br><br>As customary with pro reviews, we’ll begin with a photo tour of the unit so you can get a feel for what it looks like, and some of the capabilities." rel="nofollow">
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  • #2
    The [COLOR="Blue"]first attached image shows an overall view. Referring to the [COLOR="Blue"]second attached image, note the two front-panel mic pres to the left. These are the Saffire-series mic pres that are known primarily for being clean and transparent, as opposed to being “color” mic pres. Note that the connectors are Neutrik combo jacks that accommodate both XLR and 1/4” phone plugs. The inputs can handle mic, line, or instrument ins, but you need to use the included mixer applet to switch to the instrument option. Mic/line switching takes place automatically.

    Moving to the right, you’ll find gain controls for the mic pres, as well as LEDs to indicate when an input is in instrument mode. Instrument mode is independent for the two preamps, but +48V power is not: A single pushbutton enables +48V for both inputs simultaneously.

    Next up are indicators for power, FireWire connected, and LKD (whether the unit is locked to clock or not). Also note the five-LED meters, and the calibrations. The lowest LED is really an activity LED, as it shows when a signal exceeds -42dB. At the high end of the scale, there are LEDs for 0, -3, and -6 (as well as -18) so it’s pretty easy to see if a signal is clipping, or getting close to it.

    Further to the right is the monitor level control, along with Mute and Dim switches, and finally there are two independent stereo headphone jacks, each with their own volume control.
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    • #3
      Now let’s check out the rear panel in the [COLOR="Blue"]first attached image. From right to left, the panel starts with line ins for inputs 3 and 4. These are balanced ins. To the left are six line outs, so yes, you can do 5.1 surround if that’s your thing, or set up a separate bus for monitoring (this would require using the mixer applet, a portion of which is shown in the [COLOR="Blue"]second attached image – we’ll be getting into this in much more detail later on).

      Next are the FireWire and digital optical in connectors. The optical in can be either set to ADAT or S/PDIF for channels 3 and 4. The Pro 24 DSP also has – trala! - physical, 5-in DIN MIDI connectors. Focusrite gets major props for this, as quite a few audio interfaces these days do MIDI-over-USB, and that’s it. Yet, there are still quite a few us out there with hardware synths, fader boxes, controllers, etc. and these require actual physical MIDI connectors.

      The AC adapter jack handles the included 12V adapter, and there’s also an on/off switch. However, the unit can be bus-powered, so the AC adapter comes into play only if your FireWire bus can’t handle the power for some reason, or if you’re using a laptop with a 4-pin FireWire connector that doesn’t provide power. The adapter is a “global” type that handles 100-240V, 50/60Hz, and comes with interchangeable plugs for different countries.

      Finally, there’s S/PDIF in and out on RCA coaxial jacks – and that’s it for the rear panel.
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      • #4
        As I always like to say, it’s not a real Pro Review until I’ve voided the warranty...so let’s take the unit apart. Warning: If you’re not a geek, you’ll probably want to skip this and move on to the next post.

        The [COLOR="Blue"]first attached image shows an overview of the insides. The [COLOR="Blue"]second attached image shows the XLR connectors; note that they’re on a separate board, connected by a ribbon cable. If you somehow manage to screw up these jacks, it looks relatively easy to replace them, as they’re separate from the main board. Similarly, referring to the [COLOR="Blue"]third attached image, the front panel control board is also removable and connects to the main board via ribbon cables. If the pots get scratchy or an evil offspring jams a pencil into the headphone jacks, again, it wouldn’t be hard to replace this section.

        The [COLOR="Blue"]fourth attached image shows the output section. I’m assuming the 100uF electrolytic capacitors are coupling caps.

        Finally, the [COLOR="Blue"]fifth attached image shows the DSP board, so let’s get into the chips a bit. The main DSP heavy lifting is done by a Texas Instruments TMS320C6722B, which is a 32-/64-bit floating-point digital signal processor. It clocks at 350MHz, providing up to 2800 MIPS/2100 MFLOPS operation because it can execute up to eight instructions (six floating-point) in parallel for each clock cycle. Onboard DRAM comes from a 128MB Samsung K4S281632K. FireWire interfacing is done with a TC Electronic DICE chip, and conversion with a Burr-Borwn (Texas Instruments) PCM3168A, a 24-Bit, 96-kHz/192-kHz, 6-in/8-out audio codec with differential I/O.

        Analog-wise, the outputs are 4565 dual op amps, which feature a 4V/microsecond slew rate, input equivalent noise of 1.2 microvolts RMS, and gain-bandwidth product of 10MHz. This is all very respectable for a consumer-grade dual op amp dealing with high levels. On the mic pre side, the op amps of choice appear to be TL072 variants from ST Microelectronics, which are low-noise JFET input amps. They’re known for their low noise of 15nV per root Hertz, and a 16V/microsecond slew rate for solid transient response.

        Bottom line: These are relatively standard, upper-echelon consumer parts that are entirely consistent with the interface's price point.
        _____________________________________________
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        • #5
          I bought one of these in the first month or so they hit the market, and as an absolute rookie in the world of modern computer-based recording, I felt like the Saffire 24 was the best choice. I'm sure that some folks will consider VRM to be a gimmick, but I can think of many situations where it'll be useful. Having two headphone outputs was another major factor, and the software mixer was almost overwhelming (a mixed blessing, I guess) with so many routing options. I've only scratched the surface so far, but this seems like the type of interface that could last someone for years.

          My only complaint is that the power supply plug isn't very secure, and has popped out if I so much looked at it funny. I might try just running it bus-powered, although I tend to avoid that for no particular reason.
          Originally Posted by Captain_howdy


          ^^ this guy just said "lard tsunami".



          UNDER EDEN: The Science of Self-Defeat at CD Baby - / - Facebook - / - Official Website - / - My Blog: Extreme Metal Musician

          Member of the Jackson/Charvel Army
          ----------------------------------
          Jackson Guitars - ART Preamps & EQs - Peavey & Carvin Amps - Rocktron, Tech 21 NYC & EHX Effects

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          • #6
            I've only scratched the surface so far, but this seems like the type of interface that could last someone for years.


            Hopefully this review will help you scratch a little deeper!

            My only complaint is that the power supply plug isn't very secure, and has popped out if I so much looked at it funny. I might try just running it bus-powered, although I tend to avoid that for no particular reason.


            Bus-powering should work fine as long as you're connecting to a six-pin FireWire connector.

            Look into the jack on the back; there should be a tab coming up from the bottom that almost contacts the center pin. If it's far away from the pin, you can try to bend the tab CAREFULLY (using very fine needle-nose pliers) so that it's closer to the pin, thus putting more pressure on the connector.

            Another option is to undo the screw on the side that's closest to the power connector. Get a small piece of solid wire, loop it around the screw, then screw the screw back in firmly so that it holds the wire in place. Route the power supply cable around toward this screw, and wrap the solid wire around the power supply cable to act as a sort of strain relief.

            If this isn't clear, let me know and I'll do it to mine and post a picture.

            Welcome to the pro review, and remember that any comments or questions are always welcome!!
            _____________________________________________
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            • #7
              After subjecting the Pro 24 DSP to warranty-voiding abuse, let's hear what it sounds like. To do that, it's time to install the drivers.

              I'm installing this on a 32-bit Windows XP system, although I'll try it out with 64-bit Vista as well at some point. There's a software disc that comes with the unit with all the bundled goodies - more on that later, as well - but when it comes to drivers and mixer applets, the first thing I do is go to a company's website and download whatever the latest version might be. I hardly ever find that what's on the web is the same version as what's on a distribution CD- or DVD-ROM.

              The driver+mixer applet is a quick download (16MB). While people still have trepidation about installing drivers on Windows, that's really a holdover from the Bad Old Days. Most driver installations will not be problematic if you follow the installation instructions carefully.

              However, in order to simulate the typical user experience, I of course had to avoid reading any kind of documentation whatsoever. So, I just assumed installation was the usual protocol: Double-click on some .EXE file with the unit disconnected, then after installing the software, plug in the FireWire cable so Windows can discover the unit and finish the installation.

              So that's what I did. Focusrite is very good about warning you to make FireWire connections with both the computer and interface power off. Granted this is probably a bit on the alarmist side, because most computers implement FireWire properly. But not all do, and you don't want to fry your motherboard.

              (Side note: The first manufacturer to notice this phenomenon was M-Audio, and they put out notices about why people should power off prior to connecting FireWire. Their "reward" for this public service was to have people claim that M-Audio interfaces were inferior and would blow up your computer, which of course was rubbish - the fault lies with the computer in these cases. So, don't make the same mistake and think that Focusrite FireWire interfaces will blow up your computer - they're just advising you to be cautious.)


              Installing the drivers proceeded exactly as it was supposed, and within a couple minutes I had opened WaveLab 7, assigned its outs to the Pro 24 DSP, started playing a file, and listening to music through the headphone outs. Success!

              The [COLOR="blue"]attached image shows the mixer applet (note: I had to squish it a bit to fit in our 900 pixel wide image limitation; the "real thing" is more legible) and as you can see, I of course had to try out VRM before going any further...
              _____________________________________________
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              • #8
                Just chiming in on what has been my only negative experience with my Saffire, or more specifically with MixControl. Being of the "save and save often" mindset, I made a point to save my MixControl settings once I had everything dialed in for the various recording sources I have connected: two mics, a Line 6 TonePort DI and an old Korg pedal that I use for a cab sim. Life was good, and I didn't make any changes for a few months.

                At some point, I decided to check the Focusrite website for firmware updates and found one, so I downloaded it and installed it as instructed. Everything when fine, except that MixControl would no longer recognize my saved settings file! Now, this isn't catastrophic by any means, but for a set-it-and-forget-it sort of person who dials in their settings and then ignores them, it could be a real pain in the rear end. This also wiped out saved settings for the EQ, compressor and gate routing.
                Originally Posted by Captain_howdy


                ^^ this guy just said "lard tsunami".



                UNDER EDEN: The Science of Self-Defeat at CD Baby - / - Facebook - / - Official Website - / - My Blog: Extreme Metal Musician

                Member of the Jackson/Charvel Army
                ----------------------------------
                Jackson Guitars - ART Preamps & EQs - Peavey & Carvin Amps - Rocktron, Tech 21 NYC & EHX Effects

                Comment


                • #9
                  Just chiming in on what has been my only negative experience with my Saffire, or more specifically with MixControl. Being of the "save and save often" mindset, I made a point to save my MixControl settings once I had everything dialed in for the various recording sources I have connected: two mics, a Line 6 TonePort DI and an old Korg pedal that I use for a cab sim. Life was good, and I didn't make any changes for a few months.

                  At some point, I decided to check the Focusrite website for firmware updates and found one, so I downloaded it and installed it as instructed. Everything when fine, except that MixControl would no longer recognize my saved settings file! Now, this isn't catastrophic by any means, but for a set-it-and-forget-it sort of person who dials in their settings and then ignores them, it could be a real pain in the rear end. This also wiped out saved settings for the EQ, compressor and gate routing.


                  Sorry to hear that! But if that's the extent of your negative experiences, I guess it's much better than "So I fried my motherboard..." (Don't laugh, that happened once with me where a physical copy protection device malfunctioned. I called the manufacturer because I couldn't believe a copy protection device would be designed where if it malfunctioned, it would kill your motherboard...but they confirmed that it could. FYI this was back in the 90s and that device hasn't been used in well over a decade, so don't worry unless you're using a NuBus-based Mac!)
                  _____________________________________________
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                  • #10
                    I've ordered one of these up and should have it early next week. I'm very interested in what you think about the VRM implementation. My "room" is 11'x7'x8' and according to the mode calcs I've looked at, I'm never going to get it close to acceptable for decent mixing. So I'm hoping that using headphones can be a decent alternative.

                    Of course, I have my doubts about this system since no consideration seems to be given to what kind of headphones you're using (correct me if I'm wrong about that). The sound signatures of various studio monitors are much closer to each other than are the signatures of different headphones, I'd wager.

                    Anyway, I'd like to see your take on the Focusrite solution. And it would be great if you could compare it to something like Redline Monitor.

                    I look forward to your perspective - your reviews are always the best reads anywhere, Craig.

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                    • #11
                      All right...time to get hardcore, and get into some specs. After all, no matter how cool features like VRM are, you want an interface with solid "core" features and serious audio quality. Let's see how the Saffire Pro 24 DSP measures up.

                      I’ve done this type of testing for the Mackie Blackjack interface, and in the Phonic Firefly 808 Universal Pro Review, so if you want to compare specs with those units be my guest. As with the other units, in the spirit of testing worst-case conditions, I used the mic pre inputs set to high gain so their performance would be part of the tests. The specs are still excellent, as we'll soon see.

                      Note that for most tests, a gray line shows the left channel response, and a green line, the right channel. On those shots where it looks like I did the test in mono, rest assured it is in fact stereo; it’s just that the channels match up closely enough so that the right channel covers the left channel.

                      The [COLOR="blue"]first attached image shows intermodulation distortion+noise. If you're not familiar with how this is tested, you generate a 60Hz and 7kHz signal, then look for sidebands. You can see one sideband to the right of the 60 Hz signal peaking out at about -95dB, and another one to the right of that one that hits -100. An sideband to the right of the 7kHz signal peaks at just above -110dB; the remaining distortion products are below -110dB for all practical purposes.

                      The [COLOR="blue"]second attached image shows the frequency response. It's almost ruler-flat from 35Hz up to 20kHz, and this was measured with a 44.1kHz sampling rate.

                      The [COLOR="blue"]third attached image shows the noise level, which is generally below -120dB, with a few spikes hitting -110dB (A-weighted) This is excellent performance.

                      Now let's move on to more tests...
                      _____________________________________________
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                      • #12
                        More tests...

                        The [COLOR="blue"]first attached image shows the Total Harmonic Distortion. Note the 1kHz spike used for measurement, and a couple distortion products at 2kHz and 3kHz (both are down about -90dB). Aside from a distortion product at 5kHz that peaks at about -95dB, the remaining distortion products are mostly under -110dB.

                        The [COLOR="blue"]second attached image shows THD compared to level. The lower the level with digital signals, the greater the distortion because you have fewer bits to work with; this shows how much the signal deteriorates with respect to distortion at lower levels. At -6dB, THD is around -84dB, and at -15dB, around -78dB.

                        The [COLOR="blue"]third attached image shows stereo crosstalk. With a -6dB signal fed into the left channel, the crosstalk in the right channel is under -78dB up until about 3kHz, where it starts to rise, peaking at about -72dB at 20kHz.

                        Tomorrow, we'll do a quick comparison to the Mackie and the Phonic. This isn't so we can say one is "better" than the other, because they have different feature sets and price points. However, it does give some interesting insights into how manufacturers differentiate their products for different markets.
                        _____________________________________________
                        There are now 14 music videos posted on my YouTube channel, including four songs by Mark Longworth. Watch the music video playlist, subscribe, and spread the links! Check back often, because there's more to come...

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                        • #13
                          As is obvious from the tests, the audio performance is excellent. Comparing to the Mackie and Phonic is interesting, though, as they have more similarities than differences with respect to audio performance—even though their feature sets are very different.

                          For frequency response, the Phonic rolls off a bit faster at low frequencies, but the screen shot goes down below the range of the Mackie or Focusrite tests so we need to compare apples to apples: From 35Hz on up, all three are pretty similar except for the Mackie, which rolls off a little bit more at 20kHz. This might make a difference to your dog.

                          Regarding noise, the Phonic has a slightly higher overall noise floor. The performance of the Mackie and Focusrite are for all practical purposes identical. For crosstalk, the Mackie is the least consistent, dipping down to below -96 for the mids but rising up to about -74 at the high end and almost as much at the low end. The Phonic is the most consistent, staying generally below -84dB. The Saffire is mostly below -78dB, with a slight rise starting at 5kHz and going up to about -72dB.

                          THD is best on the Mackie, next on the Phonic, and with the Saffire spiking the highest at -90dB. For THD levels, I didn’t run this test with the Mackie, but the Saffire is definitely superior to the Phonic, with almost a 10dB difference at a -15dB input level. The difference isn’t quite as dramatic at -6dB, but Saffire still performs better. So, the Saffire’s converters are considerably more accurate at low levels. This is arguably the biggest difference among the units.

                          For intermodulation distortion I again used a different test procedure with the Mackie, so we can only compare the Phonic and Focusrite. Here, the Phonic has fewer distortion spikes, but you can also see the effects of the Phonic’s slightly higher noise floor—any distortion products below about -115dB will be masked by the noise.

                          So, what conclusions can we draw from this? First of all, these days audio performance is really good within the same general price point. Although quantitatively you can say that yes, a distortion spike at -96dB is “better” than one at -90dB, the practical difference is pretty much negligible. You’ll note that one interface might be better in one respect, while another is better in another respect.

                          What accounts for this consistency in performance? Simple: The components within interfaces have all reached a certain level of maturity and consistency. Making converters is no longer an arcane art; it’s entirely likely that the main differences in performance will relate more to circuit board layout than the components themselves. Looking at the results of these tests, I think I can say with confidence that with any of these interfaces, the limiting factor to your audio will not be the interface—for example, your mic preamp will probably be noisier than the noise floor on any of these units.

                          All of this supports my thinking about interfaces these days...once you start getting into the multiple hundreds of dollars price range, any differences in audio specs are relatively negligible. This therefore puts the focus on subjective reactions (e.g., liking one mic preamp’s character over another), and the feature set. For example, the Mackie Blackjack has fine specs and is extremely economical, but it’s also bare-bones—no MIDI, only a couple inputs, primitive software applet, etc. The Phonic’s claim to fame is USB/FireWire operation, and lots of I/O—a very different approach compared to the Mackie or Saffire Pro 24 DSP.

                          So Focusrite includes attractive features that make it unique in its own right. Obviously there’s VRM, but also, there’s the included software bundle (which we’ll also cover). Not to get ahead of ourselves, but while reviewing a different Focusrite interface I checked out the plug-ins that come with the software bundle, and they represent considerable extra value. Another feature we’ll be talking about more is the fact that the Focusrite has onboard, hardware DSP—this not only lets your CPU loaf a little, but for live recording (and remember, the Pro 24 DSP is very portable), you can process the sound coming in to the interface. Yes, add compression to make sure your recording isn’t ruined when the singer sings a lot louder than he did during soundcheck! And the applet itself is extremely sophisticated, running circles around many competing products due to the input FX, internal reverb, VRM, storable mixes, and more.

                          Bottom line is the Focusrite gets thumbs up on audio performance, so let’s dig deeper into the feature set. Hmmm...do we look at VRM next, or input effects...how about input effects, because that’s something that hasn’t gotten a lot of attention.
                          _____________________________________________
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                          • #14
                            Hi Craig,

                            Thanks for the detailed comparisons between those three units. I am very interested in purchasing the Pro 24 DSP, but have been on the fence for a while. The feature set is very appealing. I have an old Emu 1820m and have come to appreciate its quality and the Patchmix software which provides very flexible routing. Are you familiar with the 1820? If so, can you make some comparison between the Focusrite and Emu interfaces? Particularly, how does the Saffire MixControl stack up against the Patchmix? I am certain that the Pro 24/MixControl effects are superior to the 1820's. So, I will be looking forward to your comments on that end also.

                            Thanks for all the great first hand info as always!

                            Kind regards,

                            tecknot

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                            • #15
                              Hi Craig,

                              Thanks for the detailed comparisons between those three units. I am very interested in purchasing the Pro 24 DSP, but have been on the fence for a while. The feature set is very appealing. I have an old Emu 1820m and have come to appreciate its quality and the Patchmix software which provides very flexible routing. Are you familiar with the 1820? If so, can you make some comparison between the Focusrite and Emu interfaces? Particularly, how does the Saffire MixControl stack up against the Patchmix? I am certain that the Pro 24/MixControl effects are superior to the 1820's. So, I will be looking forward to your comments on that end also.

                              Thanks for all the great first hand info as always!


                              Funny you should mention the 1820, it's been my old faithful interface for years. Interfaces for review come and go, but the 1820 is a constant. I end up using the one in the V-Studio a lot because of using Sonar, but the 1820 was a fantastic unit for its time, and still does an excellent job.

                              As a result, I've often compared it to other interfaces. Most newer units, including the Pro 24 DSP, have more neutral mic pres; there's a little "peakiness" in the E-Mu's pres. They're fine, mind you, but we've come a ways since then. FYI it might not be the pres per se, but the converters or some other element; in any case, I can hear a difference.

                              Another issue with the 1820 is the effects don't go above 48kHz. That might not matter to you, but it's worth noting and indicative of the era when the 1820 came on the scene.

                              The routing is indeed flexible, but the routing in the Pro 24 DSP is every bit as good, and in many respects, better. We'll be getting into the mixer app next, so you'll get the details then. There are not as varied a group of effects in the Pro 24 DSP, e.g., distortion and such. However, you do get solid EQ and dynamics control on the inputs, as well as reverb, and the plug-in suite (which we'll also cover) has real merit. No diss on E-Mu, but a lot of the effects in the 1820 have been eclipsed by what you get bundled with DAWs, or from companies like Kjaerhus. When the 1820 was introduced native operation was not as efficient, and there was value in having plug-ins residing in hardware. There still is - the DSP in the Pro 24 DSP is a good example of why - and of course, companies like Universal Audio, SSL, and TC Electronic have taken DSP-assisted plug-ins to a very sophisticated level. But the E-Mu effects are a little long in the tooth at this point, and have been equaled or surpassed by many other products.

                              Stay tuned for more details...
                              _____________________________________________
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