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Sabaj A20d Review (Balanced DAC)

bennetng

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Man I thought that graph was incorrectly labeled from the DX3 Pro+ review, but the ESS chip just has a very specific output at that filter I guess!

index.php

[EDIT] Looks like I was color blind about F2 and F7, so I would just point it out on the graph to avoid confusion.
white noise.png


If you want to see the most detailed and precisely named plots (apart from the ones from the datasheet), visit @WolfX-700 's website:
FTZoom-2.jpg

As a rule of thumb, ESS linear phase fast filter has the best imaging artifact suppression (120dB, as specified on the datasheet) so it is often the best one appears on the 90kHz BW THD+N plots, but the price is to slightly violates Nyquist.

The blue, dotted-line one is from the Khadas Tone Board which always show up as a template, uses the apodizing filter. Also, the filter numbers (F1-F7) can potentially be shuffled in different products, so ideally, products display and manual should use filter name instead of number.
thd.png


The brickwall and apodizing filters, at the expense of not violating Nyquist, have poorer imaging artifact suppression, and they have poorer passsband ripples as well, clearly shown on the plots below:
 
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daftcombo

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Thanks for another DAC review @amirm , the kind of review it all started with.

Could you test the competence of the Bluetooth?

Also, can the unit be used as DAC only without preamp?
 

AudioSceptic

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Definitely not compatible with any TV, eARC or otherwise. This is a made up interface that only works with select devices that have the same I2S signaling. It has zero compatibility with classic HDMI AV standard.
Is there any standard for I2S connectors? Which should they have used, as surely many will assume it will accept HDMI?
 
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garbz

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Is there any standard for I2S connectors?
No. I2S does not define any connectors. It's a serial bus interface that defines how 3 signals are interpreted. Nothing more. It was created to communicate a few centimeters across a circuit board and never intended to leave the chassis of equipment.

I2S for interconnection is a Frankenstein's monster of attempting to communicate between equipment in ways never intended:
  • I2S is the signal standard defining what 4 lines carry what data.
  • Since I2S's electrical characteristics can't transmit over distances required, LVDS is used as the electrical standard.
  • Since LVDS doesn't define a connector or cable, HDMI is used as the interconnection.
At no point was a standard defined for how this is supposed to work. It's nothing more than a few companies copying the idea from each other on which pins, connectors, and electronics to use.
 

garbz

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I know, but, AFAIR I2S is also used by the HDMI standard, so it should be suitable for connecting a TV with eARC, or is it not?
If not, what kind of device will be compatible with it?
HDMI is entirely it's own thing. It uses CEA-861 as the signaling standard for audio and video, and electrically uses TMDS.
HDMI ARC defines a spare pin on the HDMI cable to carry essentially an S/PDIF signal, not I2S.
 

hmt

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Does it have any other functionality than being a DAC?
 

nyxnyxnyx

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What a stellar performance from Sabaj.
The day my current DAC stops functioning I will have a VERY difficult time to choose my next DAC because now there are just so many great options, even wilder fact is most of them are extremely affordable now.

Great engineering + great business ethics = a booming era for gear lovers like us :).
 

beefkabob

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Definitely not compatible with any TV, eARC or otherwise. This is a made up interface that only works with select devices that have the same I2S signaling. It has zero compatibility with classic HDMI AV standard.
All interfaces are made up. Like words. ;)
 

beefkabob

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At no point was a standard defined for how this is supposed to work. It's nothing more than a few companies copying the idea from each other on which pins, connectors, and electronics to use.
Isn't that what a standard effectively is?
 

PeteL

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LOL, funny when looking for info and this pops up. Nice to have the details!
Looks like it has already been shown there are no upsides besides "boutiqueness" to I2S
The upside is futureproofing. IMO that's the main design goal of DACS, being able to be relevant in 3-4-5 years. The performance is nailed, at this point, so what to do to make yours, attractive, give features that you don't need but that are foreseen as maybe useful later. I2S is a standard not going away anytime soon. every digital audio developper works with it somewhere in the chain. Being able to bypass the USB and SPDIF receiver trough a connector is smart.
 

PeteL

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It was created to communicate a few centimeters across a circuit board and never intended to leave the chassis of equipment.
Why does that matter? Works well when you are prototyping and breadboarding. And many evaluation modules or OEM streaming or DSP modules already give access to the I2S interface trough a Pinout. What's wrong with HDMI cable transfer?
 
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Pdxwayne

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I am waiting for a Sabaj preamp with both xlr and RCA inputs/outputs. I really like using the a10h as preamp, but using RCA increases the hum from my speakers. Would love to have sabaj preamp with xlr, but 50% cheaper than Topping's preamp. ; )
 

GimeDsp

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Having no standards for this I2S thing crosses the line.
 
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PeteL

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OK, now I am angry there is an I2S connector on this DAC.

Having no standards in what you eat or who you date is one thing, but this I2S thing crosses the line.
I hear you, but really, I'm too lazy to calculate this, but a bit too much fuss is given to this, we are talking data in the kHz range, not in Mhz, it's in the grand sheme of things, low frequncies. relatively short cables, a small resistor at the driving end and return loss is insignificant really, Yes we would like to have firm specs but in reality over a couple feet data will keeps its integrity just fine.
 

GimeDsp

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I hear you, but really, I'm too lazy to calculate this, but a bit too much fuss is given to this, we are talking data in the kHz range, not in Mhz, it's in the grand sheme of things, low frequncies. relatively short cables, a small resistor at the driving end and return loss is insignificant really, Yes we would like to have firm specs but in reality over a couple feet data will keeps its integrity just fine.
Coming from doing pro audio/studio work, installed audio/video for churches and light electrical, I can tell you standards for audio/video/electrical are very important, I just can't imagine installing a connector without a standard, very esoteric.
 
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