Meridian Ultra DAC - Q/A With Richard Hollinshead

Q&A with Richard Hollinshead, Meridian’s chief technical officer

Packed full of ground-breaking technologies and world firsts, the 24 bit/384kHz Meridian Ultra Digital to Analogue Converter (DAC) brings Meridian's renowned expertise and pioneering reputation to the analogue realm.

We posed some of our burning questions, regarding the revolutionary DAC to Meridian's CTO, Richard Hollinshead.

We’re setting a new reference standard with the Ultra DAC –  can you tell us about the features that establish this benchmark?

We are proud to have the world's first implementation of Hierarchical Converter Technology, by MQA. This patent-pending technology employs multiple converters to increase temporal resolution while also reducing noise and quantization errors. The result is a level of performance that is unachievable with normal DACs.

Another decisive feature is our approach to the playback of DSD, using a multi-bit modulator and optimized for the time domain, which has better impulse response than is possible using conventional DSD techniques.

Ultra DAC also features a dedicated Clock card and Dual Mono DAC card construction [These features are explored in further detail later in the conversation].

We have the ability to play DXD, 384kHz PCM and DSD128, as well as decode MQA. Our goal for the Ultra DAC was to cover any format where there might be some content worth listening to and enable playback at the highest level of performance.

It’s important to note that we have a strong, tested suite of technologies that we’ve had available for a while in other products. Our goal for this dedicated DAC was to expose these technical advances in a product that could be used with analogue systems and optimized for that specific application. Also, from an engineering perspective, we can crank up the performance a bit since it doesn’t support a digital output.

As you know FIFO, apodising, and upsampling are well documented in Meridian products. For more information visit here: meridian-audio.com/meridian-world/technologies.

Strictly analogue out? I always think of digital when I think of Meridian.

Let’s keep in mind that audio is always ultimately analogue; with the Ultra DAC, we are becoming analogue in the electrical domain rather than the acoustical domain, as done in our reference loudspeakers.

And with our Resolution Enhancement Technologies, whatever you listen to sounds amazing - we are not limited here at all.

Meridian’s role in the creation of MQA is well documented. What influence has this work had on the development of the Ultra DAC?

Our ability to deal with audio in all different formats and the ability to control the noise
floor, and particularly in the time domain, are all things that underpin both what MQA is doing with the content and what we are doing with the Ultra DAC, so is a shared philosophy of what is required. However, the actual delivery of those requirements is completely different. We have hardware that delivers on all of those aspects.

The Ultra DAC will make the best of any format that exists, as it is not content dependent. So whether you have CD or even TV audio output, it doesn’t matter where digital audio comes from, we will handle it and increase its resolution with the Resolution Enhancement Technologies and convert to analogue using MQA's Hierarchical Converter Technology in the best way possible. Simply put, the combination of the construction and technology advances allow us to get the best from any software and we’ll continue to optimize for the highest level of performance.

This is the first Meridian product to feature a Dual Mono DAC card construction. What are the benefits of this approach?

The Dual Mono DAC card construction provides absolute stability for each of the two DACs, so that each one can perform optimally. There is no interference between the two, with isolated power supplies and there is also complete isolation on the back end.

It’s important to note that there are a number of different ways to build a DAC product. We have chosen to build within one unit, where we have a completely controlled environment with no cabling between boxes. Also, having built a single unit, we create a very high level of isolation between the functional units.

Each component is optimized for performance such as the FIFO, providing isolation from input to output, multiple isolated power supplies, etc. The benefits of these techniques give us all of the advantages of separate construction with none of the disadvantages - single box construction removes external factors that could reduce performance.

Meridian’s Resolution Enhancement Technologies are very well known. Which technologies feature on this product?

Another Meridian first is the ability to select between three filter options when playing back standard resolution. This relates directly to the material you are playing rather than being specific to genre, etc.

The options include long, medium or short filters. Users will have the option to choose what best suits their personal preference and largely depends on the nature of the recorded material. It’s also interesting to try different settings, although in most instances the long filter will likely be the preferred option.

And as previously mentioned, the Ultra DAC includes FIFO, apodising, and upsampling to best handle any format that comes its way.

Could you explain a little more about the clock design?

It’s truly important for any digital audio clock to have low phase noise – the way to achieve this is to use high current design in the oscillator design so it is extremely stable. We have one further technology that is unusual; a FIFO system instead of just using Phase Lock Loop (PLL) for clock recovery. We don’t try to incrementally improve the PLL, we simply replace the PLL completely by using FIFO and the clock itself is controlled by its own DAC resulting in a system that folds down all jitter below 0.5Hz.

Speaking of jitter…

It’s most interesting to talk about our unique methods to get rid of it, rather than discussing what it is. However, I will say it is one of the things that contribute to “digital glare”, which this product eliminates.

For over three decades we have been working and refining our technologies to minimize jitter and provide a stable clock - key elements to maximize digital audio. As a result, the Ultra DAC represents the very highest performance embodiment of the technology that has been in our DSP reference speakers for many years.

Please talk briefly about Dither and Shaped Dither as it applies to Ultra DAC...

First, a full understanding of dither is essential if you’re going to work in digital audio - we have clearly demonstrated throughout the years that we know what it is and how best to handle it.

Dither needs to be correct, but you have some options with regard to how you can shape dither. Meridian has proprietary shaping of dither that optimizes performance as originally introduced with the 518 in 1995. The Ultra features the latest incarnation of this technology.

It’s important to note that one of the things we sometimes hear in the DAC market is the description of a “32-bit DAC”. We know that correct dithering gives you resolution
far below the least significant bit and keeps distortion level and signal level correct. Let’s just say that “32-bit” DACs don’t deliver 32-bit performance, as that kind of signal to noise level is not available in recordings either from the microphone or even the real world.

Meridian believes correct dithering is the way to maintain the integrity of the sound. Don’t be fooled by market claims, sometimes more bits do not deliver more sound quality.

What is the benefit of the Multi-Bit Modulator for DSD Conversion?

We have two clear advantages with this proprietary technology over what’s currently being used in the marketplace.

First, by using the Multi-Bit Modulator we can correctly dither. Second, we have the advantage of having a shorter impulse response than is offered in conventional DSD, so we improve upon what’s recommended in the DSD standard—this ultimately brings DSD closer to DXD.