Switzerland's Merging Technologies is best known for their Pyramix, VCube, and Ovation workstations. But the company also makes world-class converters. Merging's flagship Horus is a network-enabled interface that offers AES/EBU and MADI digital I/O, as well as Audio over IP (AoIP) using the RAVENNA (AES67 compatible) protocol. It has six expansion slots, allowing you to customize its analog I/O and any additional digital I/O. According to Egyptian mythos, Hapi was a son of Horus. Hence, the Merging Technologies Hapi is a junior version of Horus. The Hapi base unit includes AES/EBU and ADAT digital I/O, and it has two expansion bays. Users can configure up to 16 analog ins and outs, with many choices of eight-channel cards to handle mic or line levels. Alternatively, the left slot can be fitted with a 64-channel MADI (coaxial and optical) card, and the right slot can accept a 64-channel ProTools HD card. Hapi supports 24?bit PCM audio up to 384 kHz. Provided you have the appropriate cards installed, it can also do DXD (352.8 kHz PCM) as well as DSD64 through DSD256. I know that's a lot of options, but the flexibility is impressive.
Although I conducted my tests using standard AES/EBU I/O, it is worth mentioning RAVENNA. Designed as a mission-critical protocol, RAVENNA is an open-source standard, and it's capable of transmitting over 400 bidirectional channels of audio over one CAT5e run — at sub-millisecond latency. Many production houses keep racks of Merging Hapi or Horus units in a central machine room, while multiple rooms throughout the facility share the I/O via existing network infrastructure. Even if you don't use Hapi with one of the AoIP standards, it's a good idea to connect the base unit to your LAN, because an embedded web server allows you to access all of the Hapi's settings using a web browser.
When the review unit arrived directly from a trade show, the DB25/AES breakout cable didn't make the trip. I made an emergency call to Pro Audio LA <www.proaudiola.com>, and a handwired snake was at my door in a few days. Despite the rush, the workmanship and quality of the snake was impressive. With the wires in place, I set up the Hapi system in minutes.
The base unit's front panel is equipped with a color display, pushbutton rotary encoder, and dual headphone jacks (1/4'' and 1/8''). Its backlit Merging logo appears to be cosmetic, but its raised elements are actually two buttons. All options can be configured using the display and encoder. This would be helpful for a live gig, but I opened the web-based GUI instead; it was faster to use and allowed me to remain at my listening position.
I immediately conducted some D/A tests using source material and other DACs that I trust. I was amazing by Hapi's clarity and precision — like looking through a just-cleaned window you didn't know was dirty. Everything was more real, more focused, and simply more natural than what I heard from most of my other converters. It took quite a while of level-matched A/B'ng with my current favorite DAC to decide that the Hapi was slightly wider in L/R sound-field, while my go-to DAC was deeper front/back. There may be other DACs that match Hapi's accuracy, but I have yet to hear anything better.
A/D conversion was equally transparent. In a mastering scenario, I want the most accurate conversion I can get. By making liberal use of the GUI, I was able to gain-stage the left and right inputs to optimize headroom before clipping. Since some people purchase an ADC based upon how it clips, I should relay that Hapi did not like going into the red, and overs were represented with pop and crackle — not something desirable. This was not an issue for me, as I rarely clip my ADCs. So, if that's your bag, I suggest looking elsewhere.
Hapi is a breeze to use. Its stability, for example, is exemplary. I could change the sample-rate at any time, as often as I liked, and the Hapi took it in stride. I mention this because three, very good, very expensive competitors will glitch if you don't reboot them after a sample-rate switch. And, since some of those units have no front-panel power button, they place a big drag on productivity, no matter how good they sound. Hapi's web GUI is intuitive and beyond helpful at streamlining workflow. No crawling on the floor or walking to a machine room. Just launch, click, and done. Hapi is compatible with Windows (via ASIO and RAVENNA drivers) and macOS (via Core Audio as well as a RAVENNA driver). You no longer need to be a PC-based Pyramix owner to enjoy the fidelity offered by Merging.
The dual headphone jacks on the front panel are very convenient. Someone always seems to unscrew the 1/4'' adapter from my cans. I don't have to go on a safari hunt to find one, because Hapi doesn't care. Merging should have called this box the Honey Badger, because anything I threw at it didn't matter. Hapi doesn't care; it just does its job.
My concerns with the unit amount to minor quibbles. During my demo period, I found I could not freely route channel by channel, despite Merging's literature touting extensive flexibility in this regard. I was constrained within eight-channel banks. However, during the factchecking period, I learned about ANEMAN, an open-source, cross-platform, cross-vendor software application. ANEMAN (Audio Network MANager) allows you to route, monitor, and manage the individual AoIP channels of supported networked audio devices, as well as save and recall patches. My final issue is with the clipping indicators. Double-clicking on them within the Hapi web GUI does not reset them — it resets the gain to zero! Be warned. Click on the button labeled "Reset Peaks" instead.
I've heard cases of mastering engineers switching to the Pyramix DAW just to get access to Merging's converters. I admit being skeptical about these legends, but after auditioning Hapi, I no longer doubt these stories. The only thing I now doubt is why I returned the loaner system. I need to submit this review and contact my dealer.
(Base unit $2,495, option cards $1,200–$2,300; www.merging.com)
–Garrett Haines <www.treelady.com>