Dangerous Music: CONVERT-AD+ Stereo Converter

Veteran Tape Op readers will know that I have tremendous respect for Bob Muller and Chris Muth of Dangerous Music [Tape Op #45]. Over the years, I've contributed to many reviews of their products published here in Tape Op, and I've retold educational conversations I've had with both of them. Moreover, a number of their products are deployed in my commercial studios, as well as in my own personal studio, where my monitoring system utilizes a Dangerous Music CONVERT-2 [#109] and a Monitor ST [#60]; plus, I use a BAX EQ [#79] on every mix that I complete. Last year, I asked Bob when his company would be adding an ADC (analog to digital convertor) to its product line, given the success of the two DAC (digital to analog convertor) models in the CONVERT series. As I expected, Bob explained that a Dangerous ADC would only be released if it could meet the exacting criteria of Chris and the company's high-profile customers. I got the hint, and I told Bob I wanted a production unit as soon as one became available.

As with other Dangerous products, when I received the CONVERT-AD+ I was immediately impressed by its stellar sound, and its carefully engineered features - aspects that make this box more useful than competing units. Understanding that Dangerous had once again developed something special, I strived to assemble a group of engineers with more experience than me to co-review the product. Veteran Tape Op contributor Adam Kagan was the first person that came to mind. In between teaching college-level audio classes and working on many Gold, Platinum, and Grammy-nominated projects, Adam has written some of my favorite reviews for the magazine. Also contributing here are Mike Wells (mastering for Prince, Green Day, John 5, Parris Goebel, Tony Sly, and Gridlock) and Chris Godbey (engineer for Timbaland, Justin Timberlake, Rihanna, Ashlee Simpson, Jay-Z, Shakira, and Drake) - many thanks to Mike and Chris for taking part in this multi-perspective review. The review ends with my own usage notes and closing thoughts.

-AH

Dangerous Music, maker of top-shelf monitor controllers and audio processors for mastering and high-end mixing studios, has introduced their first A/D converter in a package named the CONVERT-AD+. Dangerous' single rack unit form belies its powerful and sophisticated feature set. The sleek and ultra-modern front panel of the CONVERT-AD+ sports round, center-lit, pushbutton switches; a high-resolution stereo level meter; and one large knob, that surprisingly is not an input or output level control. More on the specific controls later, but who is the intended customer for a stereo ADC in this world of integrated interfaces and monitor controllers?

To answer that question, let's look at the I/O of this unit. On the rear panel are two pairs of XLR connectors for analog inputs 1 and 2. The user may select between either pair, but only one pair at a time. Two XLR outputs provide duplicate AES3 digital streams. One TOSLINK optical port supplies ADAT (on channels 1/2), while a second port provides S/PDIF. S/PDIF is also available via an RCA jack. Two BNC connectors are for wordclock input and output, and a USB jack provides digital output to a host computer via Core Audio (macOS) or ASIO (Windows). So, at first glance, it appears that the CONVERT-AD+ would be best suited for a mastering studio, where the engineer could choose to capture one of two analog mastering chains to a digital recorder or DAW - and this is one possible setup. But the unit could also excel in a recording setting, where the input pairs could be used to record either of two stereo (or dual-mono) sources. Additionally, during mixing, the CONVERT-AD+ could be used to select between two analog mix bus chains. In my studio, I often switch between recording, mixing or mastering, and the CONVERT-AD+ provides useful routing and processing for all of these different session types.

Dangerous Music has implemented some very clever and unique features into this box, which will likely influence other manufacturers. Each center-lit button on the front panel changes color or brightness as you toggle or cycle through selections for input choice, clock synchronization, sample rate, level calibration, and metering. The level meters simultaneously display peak and average levels (peak over average), and the scale may be "zoomed" from an 80dB range down to a 10dB range. For mastering, this meter won't replace a full-featured LUFS meter, but it does provide much more information than the typical low-resolution indicators on converters or outboard processors. The analog input can be calibrated for 18dBFS (Avid), 16dBFS (Apogee), or 14dBFS (mastering) operating levels, corresponding to maximum input levels of +22, +20, or +18dBu; and the meters change from yellow to green at the chosen level. Standard sample rates from 44.1kHz to 192kHz are supported, and the unit can serve as a master clock (with sample rate selectable via USB or with the front-panel buttons) or lock to an external signal, as well as distribute sync to all digital outputs. For jitter reduction, the CONVERT-AD+ utilizes a custom implementation of JetPLL technology.

Two more buttons enable features unique to the CONVERT-AD+. First is the Clip Guard function, which effectively prevents a digital "over" indication on the destination device. This does not affect the audio - clipped audio may still sound clipped - but only affects the meter reading where an over condition can trigger an alarm or even be cause for rejection from certain facilities. The second feature affects the audio side of things, which is ultimately why we choose our gear. Dangerous has implemented an all-analog circuit designed by Chris Muth to enhance the audio captured by the CONVERT-AD+. The X-Former Insert button allows the user to engage a pair of customized Hammond transformers that were chosen for their specific sonic flavor, while the Emphasis knob dials in a sophisticated Baxandall-style high-shelf EQ at 300Hz, the output of which is gently compressed before it's blended in parallel to the dry signal before the transformer.

In the studio, I used the CONVERT-AD+ mostly while mixing an audiophile Latin jazz record featuring the bassist Oskar Cartaya. My mix setup is a hybrid system with various analog processing used as inserts via the Avid interfaces of my Pro Tools|HD rig. Clocking and monitoring duties are handled by an Antelope Audio Eclipse [Tape Op #96]. For this project, mix stems were routed to a custom Lawo analog summing mixer, and the Lawo's stereo output fed the CONVERT-AD+ for printing back into the Pro Tools session. The approach of this album was minimalist, with very little EQ and compression, which provided a good opportunity to hear subtle changes in the master bus processing and clock settings. The Lawo mixer is extremely transparent, with virtually no low-frequency phase shift and a very flat frequency response, so it only adds a tiny bit of dimension while allowing me to sum the analog-processed stems without another trip through my interface.

I first configured the CONVERT-AD+ and my interfaces as wordclock slaves to my Antelope Eclipse, as that is my usual way of working. The CONVERT-AD+, compared to the ADCs of my Avid interfaces, provided much clearer low end below 100Hz, with more relaxed and transparent high frequencies - a noticeable improvement in clarity and stereo imaging. When I used the CONVERT-AD+ as a master clock for the whole system, the lows and highs of the mix remained clear, while the midrange frequencies became slightly less congested and felt more open. A fair description would be that the Antelope clock makes the mix feel a bit more aggressive - maybe more appropriate for rock and pop - while the Dangerous clock sounds more natural, relaxed, and open. Next, I inserted CONVERT-AD+'s Hammond transformers, and instantly the mix gained flavor. Not as obvious as the flavor of a vintage Neve console with its warm but cloudy low end, or an API with forward midrange punch, but the CONVERT-AD+ added a density to the low frequencies that maintained the clarity, while it added some upper bass harmonics, and even lifted the high frequencies slightly. For percussion-heavy mixes, I found the transformer slightly softened the transients, which added a bit of polish to the mix. The transformer insert is either on or off, so the more input level the unit gets, the more saturation the transformer adds.

The Emphasis knob, next to and associated with the transformer, goes from zero up to a modest 2dB boost. The boost is a parallel EQ with compression and a touch of second-order harmonic distortion. The effect of turning up the Emphasis control is a "make it better" knob. Too much is just that, but the right amount can really add some magic sparkle and fairy dust to the mix. My usual processors for the "make it better" effect include the Emphasis slider on Sonnox Limiter [Tape Op #68] and the Shape knob on UAD Precision Maximizer. Usually, one of #these plug-ins can add some zing to pop and rock productions, but for acoustic music, the Emphasis circuit on the CONVERT-AD+ did the trick far better than either plug-in. Unlike the plug-ins, the Dangerous box adds sparkle without smearing the lo mids or adding any harsh artifacts. The combination of X-Former and Emphasis increases the overall level and punch of a mix without pumping or clipping the signal. For mixing and mastering, I'm sure the CONVERT-AD+ will become a staple just for these effects.

The Dangerous Music CONVERT-AD+ may be used in so many ways that this review can't cover them all. The power of its components - A/D converter, mix bus processor, and master clock - could be put to great use in any studio, and the combination of all of these functions make for a formidable piece of gear.

-Adam Kagan www.mixer.ninja

Let's talk innovation. The CONVERT-AD+ has a couple of unique features that, as a mastering engineer, I now find indispensable. The first is its Meter Scaling option. Seeing the peak-over-average balance with such fine granularity at the capture stage is something only the CONVERT-AD+ can deliver, and now that I have it, I can't live without it. The second is the Clip Guard feature. Different than an audio process like a soft-clipper, Clip Guard just performs a bit of Chris Muth engineering mojo on the digital output so that the meter on the playback device won't display an over-indicator. Why is this great? I can drive the input stage however necessary to achieve my clients' desired sound, so theycan then focus on listening to the playback instead of watching meters for red lights. Essential.

Now, let's talk about what matters most - fidelity. I use a highly customized ATR-102 1-inch, 2-track for tape layback in the mastering process quite often. My clients and Ilove the warmth and vibe that only tape can bring to a digitally recorded project. Unfortunately, even with the go-to mastering converters so highly regarded today, there isalways something being sacrificed when I convert back to digital, whether it is image, feel, or clarity. I was excited to get the CONVERT-AD+ and put it through its paces; and I haveto say, this box delivers. I went through a variety of material across a number of different analog paths, including tape layback, tube-heavy processing, analog color boxes - youname it. Playing back the captures from the CONVERT-AD+ was stunning. The height, width, depth, and detail preserved by the CONVERT-AD+ puts it in its own class. There's a euphoniccharacter that I'm simply not hearing from my other converters. Height is a hard one for converters to capture accurately, I have noticed, and nothing came close to theCONVERT-AD+. With my other ADCs, the "analog mojo" always seemed to be collapsed a bit - compromised in some way.

Finally, I am hearing a true representation ofeverything I love about my tape machine, tube gear, and the analog glory we work so hard to attain in modern recordings; and the price tag is the ultra-bonus. Half the costof anything in its class, delivering twice the results - how can you beat that?

-Mike Wells www.mikewellsmastering.com

I've always loved Dangerous Music. When the recording world was transitioning away from large-format consoles and tape machines, Dangerous was there, providing ergonomic solutions that actually felt more like upgrades than compromises. I'll never forget the feeling on the day we got our original Dangerous 2-BUS [Tape Op #35] and Monitor [#60] up and going. Listening to stereo mixes out of Pro Tools using the Dangerous Monitor (instead of just two channels on the old console) was such a vast improvement. We were no longer lamenting the past; we were embracing the future.

Fast forward a decade and a half, and Dangerous Music is still a huge part of my workflow. I now use a CONVERT-2 [Tape Op #109] as my primary mix bus DAC, out to a Shadow Hills Mastering Compressor and a Dangerous BAX EQ [#79]. Until the end of last year, I was bouncing between a few different ADC options. The first option sounded closest to the source, the second provided a nice stereo image and color, and a third handled clipping better than the others - but they all missed the mark in one area or another. All of the testing and moving around had me wondering when someone would finally make a converter that could do all these things without compromise. I was also wondering when Dangerous would give us a path back into the box. Their DACs have always been among the best, and it only seemed logical for them to give us an ADC as well. Dangerous was a few years late, but they far exceeded my expectations. My first exposure to the CONVERT-AD+ was limited to a five-day beta test. Marek Stycos, a professional cool guy of the highest order, arranged to get me a CONVERT-AD+ a couple months before the actual release. I knew I had to work fast, only having a handful of days with the Dangerous. Would this finally be the ADC to check all my boxes?

The short answer here is yes - and more. Need an honest, no frills conversion? Got it. I find the phantom center and stereo imaging just perfect without feeling exaggerated in any way. Want a little color and magic? Has that too. Just engage the X-Former insert and dial Emphasis to taste. Want to run hot and get a little more level? Just turn on Clip Guard, and clip to your heart's content without hitting any red lights. It's important to note that Clip Guard is not a limiter. You're still clipping - just not hitting red in your DAW - so be careful. There are several handy features that seem like no-brainers: You can easily switch calibrations between 14, 16, and 18dBFS right from the front panel. Two sets of stereo inputs make it easy to switch between tracking and mixing modes without much fuss. For example, your mix gear patches can stay intact on input 1, and you can switch to input 2 for a mic preamp or whatever. To top it off, you get a beautiful, usable meter with a couple of scaling options. Needless to say, the two months after sending the beta unit back were some of the longest. I'm now a proud owner of a CONVERT-AD+, and haven't thought about what my ADC might be missing since. That's a pretty big statement for a gearhead. If you're like me and tired of loopback tests and double-blind converter shootouts, get the CONVERT-AD+ and get back to work, knowing you've got one of the best options any price point. It's easily the best converter I didn't know I was waiting for.

-Chris Godbey jvuentertainment.com/talent/chris-godbey

Regarding the many features and the overall sound of the CONVERT-AD+, I agree with everything Adam, Mike, and Chris wrote, but being the Gear Geek, I do have some additional notes from my own testing and use. Transient response of the Dangerous box is exemplary. The CONVERT-AD+ captures detail with a precision that has more to do with rise time, settling time, and overshoot - stuff that our ears can definitely hear but we don't tend to visualize as easily as we do Hz, dB, and SNR. I believe that many of the words used earlier in this review - like open, clarity, height, center, and image - relate directly to transient response.

Regarding the X-Former and Emphasis features - with X-Former enabled and Emphasis at 0, I hear mostly odd-order "thickening" in the bass and lower midrange. Consequently, bassy notes benefit from extra "oomph," despite the very shallow low-frequency rolloff (0.5dB at 40Hz, 1dB at 10Hz) that is mentioned in the manual. The manual also explains that X-Former adds energy "folded up an octave," but I don't hear the second-order harmonics in the lows until the input is hit hard. When this happens, percussive elements, like kick drum and toms, gain extra energy and "sweetness."

As I turn up the Emphasis knob, the odd-order thickening starts to affect the whole spectrum (not just the lows), but really only on the peakier/louder stuff. In other words, dynamic material becomes livelier, without getting cloudy. Meanwhile, the second-order sweetening comes up in the lower midrange and in the highs, increasing dramatically as the knob is turned all the way up to 10, even at lower input levels. Importantly, this sweetness seems to leave the midrange mostly untouched (except when hard hits result in odd-order thickening). Therefore, smooth vocal lines and lead instruments (that are not overly punchy) remain clear and focused but gain that extra bit of sweetness in their timbral regions. Or to put it another way, it's as if the saturation effect is parametric and is tuned to leave 1 to 3kHz clear - in between the peaks/hits/notes. The end result is a control that lets me dial in some excitement and sugar without dirtying up critical midrange.

When I shared my findings with Bob Muller, he answered, "Your perceptions are definitely on. Chris Muth worked hard to make this circuit obvious enough to be useful when tracking a vocal or instrument, but subtle enough for use in mastering where the situation requires a final touch that won't ruin the work that came before, staying clear of the upper mids, and without a heavy-handed broad brush. It took a while and a fair bit of tweaking."

I also asked Bob how he would differentiate the X-Former and Emphasis features from the Color circuits in the Dangerous 2-BUS+ [Tape Op #112]. He replied, "The tone circuits on 2-BUS+ were crafted primarily with mixing in mind. They are a bit more obvious and appropriate for assigning to a single track or stereo stem (in the case of Paralimit and Harmonics), as well as putting across the entire mix. What we wanted for CONVERT-AD+ was a different transformer tone and a subtler emphasis to give a track some lift and cohesion. It is wholly different from any of the three 2-BUS+ effects."

At some point in my conversation with Bob, I joked that I understood the reasoning behind his company's name. It's Dangerous, as in Dangerous to my studio budget! Needless to say, I'm also a proud owner of a Dangerous Music CONVERT-AD+, and it's become an essential part of my tracking and mixing signal chains. It's also now my studio's master clock.

-AH