Obviously, that’s not everything, since he elaborates in a really insightful and interesting way on those so often – as it turns out – misused word “Multibit”:
“Multibit” DACs tend to break down into three categories these days:
- Discrete multibit (put together discrete resistors to achieve about 12-14 bits of linearity due to limitations in resistor matching, unless heroic ($$$$$) characterization and compensation is used. We don’t do this, because we don’t believe this is the correct approach.
- A handful of old, possibly repurposed or “pulled” audio multibit ICs from the golden age of these devices (late 1980s to mid 1990s). We also don’t do this; we do production quantities and cannot rely on these parts being available or reliable.
- Simply lying, as in calling delta-sigma parts “multibit,” since they may use 2-5 bits, rather than a single bitstream (DSD). This name can be applied to any ESS or AKM or TI delta-sigma DAC, because they all use more than one bit, but we consider multibit to mean “16 or more actual bits, integrated on a single chip with good linearity.”
Instead of this, we decided to use actual integrated multibit DAC ICs, from 16-20 bits, which are limited these days to high-precision applications, such as medical imaging and defense. These devices are not intended for audio; they are more expensive and monumentally more difficult to work with. As a result, we’re the only company in the world using these kinds of parts.”
Jason also refers to two other important things when I asked him, why did they go the lengths to implement all those fancy medical or military-grade stuff that nobody in the audio dares to use:
“I touched on this a bit above, but the main thing is that these chips are all cast from the same mold—as in, they are designed to take 16-20 bit data and convert it to a number. No delta-sigma approximation, no guessing. Modi Multibit uses one 2-channel 16-bit Analog Devices chip. Bifrost uses four 2-channel 16-bit TI chips, as does Yggdrasil LIM. Yggdrasil MIL uses four 20-bit TI DACs and is the highest performing multibit DAC ever created, easily surpassing the performance of the golden age devices like PCM63 or PCM1704.”
Please notice the parts containing “no delta-sigma approximation, no guessing” as well as the comparison to some of the well respected in the audio community chips from Burr-Brown.
Having the clearer picture let’s take a look at some specs and connections as well. Modi Multibit has a USB-C input, as well as coaxial (S/PDIF) and optical (TOSlink) ones. All of those inputs support the same Bit Depths and Sample Rates, which max out at 24 bits and 192 kHz. Somebody would ask here, why no 384 kHz or even higher maximum possible sample rate frequency here? Well, the thing is that most of the so-called hi-res material is limited nowadays to 192 kHz anyways. And the other is that – you won’t be rather buying Modi Multibit 2 to feed it with the MHz-range signal from, say, HQPlayer. The latter usage scenario doesn’t make sense, bearing in mind the custom digital filter. But, for those, you would like to try it – albeit with the 192 kHz – you can still have it. Because the Modi 2 Multibit now has the NOS mode, which stands for “non-oversampling”. And this means exactly that: the built-in, based on Analog Devices’ SHARC DSP filter will be omitted. And what you will feed the Modi – it will enter the two-channel AD5547 conversion silicon without that custom digital filtering. Just one thing regarding all those frequencies and bits: Modi won’t do DSD, if you really need it – you will have to do the sample rate conversion in software like Roon, Audirvana, HQPlayer or even the free Foobar2000. In any other case, where the PCM is involved – you’ll be perfectly fine.