Sorry for UK friends, I just came back from our festival days so I am to late to edit original post.
Ferrum Audio Wandla - teardown
As my first impression of Ferrum Audio, that should be HYPSOS power supply with hybrid design.
HYPSOS has interesting design which I don't like it, but we still can see the digital control is good.
OOR headphone amp and ERCO DAC with hp come after HYPSOS, now is WANDLA
There are three edition of WANDLA, pure DAC, Goldensound edition and DAC with HP AMP.
This WANDLA is pure DAC which borrowed from my friend.
You can see "Fe" logo and color touchpad screen on front panel.
The rear panel, XLR / RCA output and RCA input, I didn't know why RCA input until I found the HP amp config. Rest are AES/COA/OPT/USB/I2S/ARC/Trig and two power input. It's rare to see USB-C and HDMI ARC on DAC. Those two power input design for bundle selling their PSU product.
The bottom side, actually the top/bottom cover should be SPCC. The feet used rubber foot and I believe they should use better foot than regular rubber foot in this price.
Inside, it can sperate as 5 parts. The left area is power source, and upper area is I2S/ARC input board.
Digital processing board is in the center, right upper area is volume control and input/output buffer and the DAC circuit are in the lower right area.
There is no component on back side, only trace routing and vent hole.
Touch panel, it seems the use customized components like FPC cable with IC and will be a problem on 3rd party repair.
Power input side, the jump wire on the 4pin connector should be CANARE 4S6, then go to SMD fuse with socket on PCB. There is another one SMD fuse for DC-in jack but didn't show on photo. Rest components used for control power on/off like MOS, then go Pule PA2743NL choke as system power. BTW, if you connect power cord then connect adapter to DAC then you may see a small sparkle on DC-in jack. That's why the designer add lots of TVS diode as protection on power input stage.
There are many power sources after power choke, it used two sets of LT8641 for ±17V then go LDO as analog power source.
There are two sets of LT3088+LT3090 after LT8641 for ±15V separated for left and right channel components.
It's rear to find this separated power design, I saw different stage but none of them used for different channel.
I can only guess this designed for better crosstalk performance but I am not sure.
Crosstalk should be related to layout routing and volume control, less concern from power.
5VA used LT8609A and C-L-C-L-C filter on output, it should be the solution to reduce ripple peak on different frequency after measurement. The digital 5V power source used LT3757 which means they built a Flyback SMPS on board, probably for higher current and higher efficiency. This DAC will get hot after work couple of minutes, I think MCU may take lots of loading on filter.
Digital control board, used SMSC USB PHY USB3315, SPDIF DIX4192 and ST HDMI2C1-6C1 for ARC.
Then go to STM32 MCU for DSP, and one VCXO on board probably used for PLL of MCU. Rest one 24Mhz used for USB3315.
There is another 49Mhz on back side of digital control board, it should use for DIX4192 but that don't meet requirement on datasheet. The line driver DS90LV032A used for I2S signal.
DAC chip ES9038pro and his partner, Ref clock used ABLNO 100Mhz which is as good as CCHD-950
AVCC used ES9311Q, rest 1.2V and 3.3V used ADP151ACPZ, textbook level design on DAC power.
But it's rare to find THS3112 on I/V OPA except in some threads of DIY forum. Then 2pcs BUF634A per channel as buffer that looks more like a headphone amp. The one after BUF634 is OPA1632 as LPF. To be honestly I am not fully understanding whole design here.
DAC output connect to AXICOM relay to switch signal between RCA input and DAC, then do analog volume control by MUSES72323. The output buffer of MUSES72323 is LT1364 then go to upper side relay.
The upper relay may use for signal switch between output and headphone board in another SKU.
Output buffer used LT1364 and OPA2182 as DC servo, the designer likes to use high speed OPA.
RCA input buffer used LT1364 then OPA1632 invert as balanced signal, then go back to relay before volume control. I don't know why to add an RCA input in the beginning until I find another version with headphone AMP on website when writing this review.
RCA connector used unusual type and looks shining, but actually I took this photo to explain the output signal connection. RCA and XLR hot used same signal just separate by resistor. It may be conflict when connect both RCA/XLR in the same time.
A quick test for THD+n, ADC is Cosmos ADC Grade B and Topping HS02 USB Isolator.
The result is around 111.5dB, the noise floor is a bit higher than rest SOTA DAC because designer didn't pick those ultra low noise OPA like OPA1612.
Let me know any you have any question on this report, thank you.
- how many layers make up the main board?
