To the mod who moved this OP to a massive thread about DAC sound signatures (and everyone else reading because I added more info to the thread in here too): this thread is not about sound signature, it's about the internal operation of recently manufactured multi-bit DAC chips (specifically the new AK4499 Velvet, but also others), which I've come to understand may be imposters compared to others. Imposters? Imposters! :not true multi-bit chips like the ones made in the past, but somehow a hybrid of delta sigma + multi-bit, which, being different, may affect performance. At the end of the thread I did have some words on the sound quality of my L70 Velvet, because to me, it sounded vastly superior to the [too many] other Topping DACs I have. Fun fact: the only reason I currently know the AK4499 Velvet in my E70 Velvet is a multi-bit design, is because I was looking for a possible explanation for my perceived [but maybe imagined..] difference in clarity between it and my DX1, E30 II, E30II lite, and E50 (I do have reasons for all of those except the E50, which I planned to return but missed the window for). ANYWAY! That bit at the end of the thread was
very secondary to its primary focus, which, again (to be sure), is not discussing the implementation of the AK4499 Velvet in the Topping L70 Velvet, but the AK4499 Velvet itself: information on its design and basic operation, and maybe information on other, more recently manufactured multi-bit DACs if they're similar. I removed what I had at the end of the OP (regarding sound comparison) so there is no confusion.
Thread:
I've got AKM's 4499EX in my Topping E70 Velvet. I'm under the impression that the 4499EX is a two-chip solution - the 4499EX + comes with a 4191EQ
From AKM: "The AK4191EQ is a new concept Multi-bit stereo Premium Digital Data Converter employing VELVETSOUND™ technology. By using the AK4191EQ to process the digital signal for D/A conversion, we have minimized the effects of digital noise within the analog output, resulting in a perceived improvement of the ratio of signal to noise. The AK4191EQ has a built-in digital filter with multi-bit sigma delta modulator and 256 times oversampling processing. A wide variety of music can playback by inputting 1536kHz PCM data and DSD1024 data."
I understand this to mean the AK4191 is the chip that goes between the digital source (coax, spdif, USB, HDMI etc., etc.) and the AK4499.
What I don't get, though, is why there's a sigma delta modulator in it though... wouldn't that nullify the [alleged] benefit of the AK4499 being multi-bit?
Something else that's confusing is AKM says the 4499 and 4191 are separate to keep the analog filtering and digital processing in separate packages, but then they go ahead and say the 4919EQ processes the digital signal so that there's less noise on the 4499's eventual output... So if the 4191's input is already digital, what's this sigma delta going on for? T
And another thing: the low-pass filter on the analog audio output... you know, the thing that usually brings things down to -60dB to -100dB by 24kHz or so with a 44.1kHz... is that still in the 4499? Or is it in the 4191? So much of what AKM has said appears to be contradictory or just plain impossible!
Also, with the AK4499 Velvet (technically AK4499EX, and when packaged with the 4191EQ, called the AK4499EXEQ):
Top of Page 1 of datasheet for proof:
View attachment 352942
Where is its resistor bank? Is it in the chip???
I'm pretty new to exploring the intricacies of DACs past their advertised specifications and audible sonic qualities, so sorry for if any of the questions are pretty stupid... (Not an excuse but a reason: I had a desktop USB/toslink/coax DAC I was really happy with for almost 10 years, and it broke (accidentally, by my hand
), and now I'm interested in learning more about DACs. I do think I've been lucky to find my replacement as quickly as I have, but the journey isn't over yet -I'm still trying to learn more
And finally (& maybe most importantly...) : is the AK4499 a good example of a modern multi-bit DAC - basically made the same way but with slightly newer manufacturing technologies -, or is it an imposter - a delta-sigma DAC masquerading as multi-bit (like I said, I haven't been looking long, but I've briefly come across people saying some modern multi-bit DACs are weird hybrids or something... from what I've been able to extrapolate from what's been suggested here, there, and everywhere: a delta-sigma type DAC with unconventional output is run in a way (maybe at a higher frequency?) that it's able to output like a multi-bit DAC through multiple pins, but there are less pins and resistors and the clock is doubled up (well not doubled, but maybe 10x - it's like 5 bits instead of 20 or 24 bits). I don't know, it's messed up what I've seen and I'm tired of guessing so I'm hoping someone knows what's going on!
