I broke down... I bought this card for 250 euros. the design of the ultra-low noise power supplies and separate ground planes spurred me into action! What do the DAC pros think here... I'm not looking for the ultimate, I don't have the financial means... And I think it's still DIY, a bit qualitative all the same...🙂
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How many layers are the PCBs?
I will say this about Aliexpress or equivalent dacs (if that's what this is), which is that IME you don't get more than you pay for. Maybe you get less, though. Opamps and or passive components may be fakes. The main featured chips though, tend to be real. Film caps may be nonlinear mylar, not polypropylene. Ceramic caps are X5R or worse. Two layer boards may be used, when you need at least 4-layers. Stuff like that.
I will say this about Aliexpress or equivalent dacs (if that's what this is), which is that IME you don't get more than you pay for. Maybe you get less, though. Opamps and or passive components may be fakes. The main featured chips though, tend to be real. Film caps may be nonlinear mylar, not polypropylene. Ceramic caps are X5R or worse. Two layer boards may be used, when you need at least 4-layers. Stuff like that.
I receive this dac, normally on Saturday.
Then wiring and box assembly, this is for me the part as interesting as the final listening.
A little comparison with my other dac, not necessarily fair, the USB cards are different as well as the number of channels.
Well, it's alive! 🙂🙂🙂 Despite a big scare because of a rider...😳 The translations from Chinese are hard to interpret. In short, the volume is thus found at full volume on a single channel... (test speakers) The speaker coil got hot, I still have the smell of it in my nose! But it survived, still 8 ohms on the multimeter. Hard wiring and testing on various modes 16 to 32b and 44 to 384 Kh in PCM, Dsd to check later... No noise or hiss at max volume! The sound seems promising, I loved the sound of the cymbals and plucked strings.
It's subjective, not definitive, I'll try after putting it in the box on my living room speakers... 🙂
It's subjective, not definitive, I'll try after putting it in the box on my living room speakers... 🙂
I guess a rough translation of the french "cavalier"?
I believe we rather use the word "jumper" for those... I can though understand the F aren't using "sauteur" LOL!
Glad all is well at the end and good luck for the next steps
Claude
I believe we rather use the word "jumper" for those... I can though understand the F aren't using "sauteur" LOL!
Glad all is well at the end and good luck for the next steps
Claude
We used to call those 'handbags' when I was working in the industry.
"A handbag?" <Lady Bracknell voice>
"A handbag?" <Lady Bracknell voice>
Imho those caps are not for sound, swapped them all on a similar constructor with 4493 dac. The difference in sound is just huge, but it is very difficult to choose a combination of different capacitors. It takes a lot of time.
As for my ears and system i've choose Nichicon FG for digital power supply, Elna Silmic II + Muse ES for VREF + VDDL/R + VCOML/R.
Very hearable place also in the power circuit of op amps...
As for my ears and system i've choose Nichicon FG for digital power supply, Elna Silmic II + Muse ES for VREF + VDDL/R + VCOML/R.
Very hearable place also in the power circuit of op amps...
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Coupling or filtering capacitors?
This board can be modified as desired, nothing is finalized yet.
The SMD capacitor appears to be "Tantalum", the resistors "Melf".
I leave these in place.
Brief !
I welcome all (good) information, don't hesitate! 👍
I'm about all KY electrolityc caps, here is a photo of my kit (don't smile how it looks, this is only test box)
The filtering capacitors, I think I'll save them...
I have to target as a priority, the chemicals on the signal path (there aren't many).
By the way, have you easily configured the JUMPERs ?
I have to target as a priority, the chemicals on the signal path (there aren't many).
By the way, have you easily configured the JUMPERs ?
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According to information on their site, there is a table with jumper settings. Please look the marking of op amps at the I/V stage (soic near the 4499 chip) and op amps near RCA
I bought one of these boards, minus the DAC chips. Couple interesting observations and a question.
The sub board that the DAC and I/C opamps are mounted to is at least 3-4 layer. The main board is 2 layer and pretty well separated into analog side and digital side with the subboard spanning the two sides. everything that is not a signal or power carrying trace is ground plane. The ground planes are top and bottom as well as split analog and digital.
The chips on the one I received appear to be legit, although I opted for the kit minus the 4499/4191 so I bought them plus all new electrrolytics from Mouser to be sure I got quality parts that I have used before and like. There are 4 resistors and 4 capacitors (not counting supply filter caps) associated with the I/V converter. I cant tell if they are any good in terms of performance at this point but they do match each other well within 1%, so they will stay for now.
I already have a USB DAC that has used the AK4497 "kit" from the same manufacturer (GeeDIY) and it looks like this implementation mirrors a lot of that so it seems power supplies, USB to I2S board, my LP filter/line amp stage, and so on that I have now can be reused without much bother.
With the 4497 I took the differential outputs from the AK4497 itself to my own discrete opamp based LP filter amp board. I am doing the same here which means I am using literally nothing on the analog side of this AK4499 kits main board. The 4499 board itself is larger than the 4497 board and my enclosure has no extra room, I cut the analog part of the board off and that allows it to fit in my enclosure without moving anything.
Now a question - after some background. The AK4497EX "datasheet" says, on page 29 that the I/V opamps must be powered on after the 4499 and powered off before the 4499. This it doesnt appear to have any control in place to do this. The +/-15VDC for the LP filter and I/V converter cone in directly to both functions so their power on/off relative to the power for the 4499 seems to be completely dependent on how quickly the 15V comes up after power is applied compared to the three 7-9V supplies for the 4499 board. There is nothing in the GeeDIY online instructions for the 4499 module that suggest this is needed, and nothing on the board that suggests it is addressed in any way on the board. The AK4499 datasheet DOES state that "There is a possibility of IC destruction due to breakdown of the withstanding voltage of the analog output pins (IOUTLP/LN/RP/RN) if the power supply of the external operational amplifier is turned on before power up the AK4499EX. Therefore, connect a Zener diode (VRWM = 6 to 7 V) between each VDDL/R and VSSL/R if the power up/down sequence shown in Figure 13 cannot be followed." I believe these zeners are shown on the drawing on page 45 of the datasheet - labeled ZD, and on the AK4499EX evaluation board manual schematic page 45 labeled D1 and D2.
Question. Has anyone implemented this on this board or anywhere else when using the 4499EX? From the description by AKM it looks as though limiting the voltage on VDD to under 6-7V will somehow protect IOUT in the event of a higher voltage being fed back from the I/V opamps during power up and down.
The sub board that the DAC and I/C opamps are mounted to is at least 3-4 layer. The main board is 2 layer and pretty well separated into analog side and digital side with the subboard spanning the two sides. everything that is not a signal or power carrying trace is ground plane. The ground planes are top and bottom as well as split analog and digital.
The chips on the one I received appear to be legit, although I opted for the kit minus the 4499/4191 so I bought them plus all new electrrolytics from Mouser to be sure I got quality parts that I have used before and like. There are 4 resistors and 4 capacitors (not counting supply filter caps) associated with the I/V converter. I cant tell if they are any good in terms of performance at this point but they do match each other well within 1%, so they will stay for now.
I already have a USB DAC that has used the AK4497 "kit" from the same manufacturer (GeeDIY) and it looks like this implementation mirrors a lot of that so it seems power supplies, USB to I2S board, my LP filter/line amp stage, and so on that I have now can be reused without much bother.
With the 4497 I took the differential outputs from the AK4497 itself to my own discrete opamp based LP filter amp board. I am doing the same here which means I am using literally nothing on the analog side of this AK4499 kits main board. The 4499 board itself is larger than the 4497 board and my enclosure has no extra room, I cut the analog part of the board off and that allows it to fit in my enclosure without moving anything.
Now a question - after some background. The AK4497EX "datasheet" says, on page 29 that the I/V opamps must be powered on after the 4499 and powered off before the 4499. This it doesnt appear to have any control in place to do this. The +/-15VDC for the LP filter and I/V converter cone in directly to both functions so their power on/off relative to the power for the 4499 seems to be completely dependent on how quickly the 15V comes up after power is applied compared to the three 7-9V supplies for the 4499 board. There is nothing in the GeeDIY online instructions for the 4499 module that suggest this is needed, and nothing on the board that suggests it is addressed in any way on the board. The AK4499 datasheet DOES state that "There is a possibility of IC destruction due to breakdown of the withstanding voltage of the analog output pins (IOUTLP/LN/RP/RN) if the power supply of the external operational amplifier is turned on before power up the AK4499EX. Therefore, connect a Zener diode (VRWM = 6 to 7 V) between each VDDL/R and VSSL/R if the power up/down sequence shown in Figure 13 cannot be followed." I believe these zeners are shown on the drawing on page 45 of the datasheet - labeled ZD, and on the AK4499EX evaluation board manual schematic page 45 labeled D1 and D2.
Question. Has anyone implemented this on this board or anywhere else when using the 4499EX? From the description by AKM it looks as though limiting the voltage on VDD to under 6-7V will somehow protect IOUT in the event of a higher voltage being fed back from the I/V opamps during power up and down.