Inside FiiO D3
More on Fiio D3
3.3V or 5V OPERATION?
According to the datasheet, the Cirrus 4344 DAC can operate at 3.3V and at 5V. At 5V operation, you get 2 dB better performance pretty much across the board.
The current operation of the D3 (original model), seems to be operating at 3.3v since the input voltage to the device is 5V.
However, by measuring the voltage on the power pin of the DAC (VA, Pin 9), the DAC is actually operating at 4.8V which is pretty much ideal for best performance.
In addition, the output stage opamp is also operating at the same 4.8V. Therefore, there is no need to do any modding to get better performance.
But a good and easy mod here is the input capacitor. Space is very tight, must use similar sized capacitor. Used a standard class ELNA 1000 uF capacitor, bypassed with a 22nF film cap. The original was 470 uF, 16V.
Detail after removing existing capacitor
After the large capacitor, power goes through a ferrite, then it is bypassed by two small value ceramic capacitors and connects to V+ in the opamp
Detail after replacing capacitor and bypassed with film cap
NEW VERSION: D3K TAISHAN
WM8805 replaced by Cirrus CS8416
As FIIO shared when they first introduced the D3, the WM8805 (perhaps) has been discontinued and they have replaced the chip with the CS8416. This is the new “D3K TAISHAN” model. (Taishan as in “Mount Tai”, a famous place in China where emperors used to worship the heaven and to pray for peace and prosperity)
A reader shared and internal photo (see comment #40):
Comparing with the original version, the layout has been completely redesigned. The DAC and the opamp remains the same.:
Backside of D3K Taishan edition. Date is 11 months after the original V1 version.
Same reader alerted me that there is “in-between” version between the original D3 and the new D3K. We call it D3V2. This version uses the WM8805 part but there are omitted components in (what I believe) is the power section for the opamp. You can check the comments for comments about the performance of this version.
I’ve made a composite image of the D3 Original and the “D3 V2″ which is shown below:
Here is the backside of the D3 V2:
The case is identical with V1. In the V1, the RCA connectors are silver color. The RCA connectors in V2 are gold plated. (V2 is the one to avoid)
Update 2/14/12: More information on the DAC, I2S to External DAC, see end of this post
WM8805-BASED DAC FOR $30
I was intrigued by this DAC based on the industry-leading Wolfson SPDIF receiver WM8805. According to the specifications it is capable of 24bit/192KHz operation and it only costs $30. (Even less nowadays)
Just like any good DIYer, the first thing I did was to take it apart…
The famous Wolfson WM8805 SPDIF receiver. Even though it is capable of muxing up to 8 SPDIF sources, it is configured in hardware mode and therefore it is configured to have a single input into the receiver. The device has a coax and a toslink input and these are selected with a single pole switch. Notice also the use of a seam-sealed crystal instead of the more traditional can (most likely for size).
The WM8805 interfaces a Cirrus Logic 4344 DAC (“344″ indicates fixed I2S configuration). This DAC has pretty decent specs at 105 db SNR and -90 db THD+N, a cut above the DACs found in this price range (in reality, you can’t find any DACs at this price range which is a new low). The CS4344 DAC is also found in the Apple Airport Express 802.11n version.
The analog output of the DAC connects to a TI LMV358 opamp
You can see the I2S lines (the 4 diagonal traces), ready to be tapped…
The power is supplied by an external 5V DC switching supply through a standard mini-USB connector. The 5V line (the uppermost trace from the USB connector) connects to a 6.8 (R37) ohm resistor and to the main PS capacitor (470 uF 16V). This provides a first stage RC filtering to the incoming power.
The 5V incoming is filtered through L5 and further regulated with a simple discrete Zener diode circuit (basically a shunt regulator) to 3.3V which feeds the DVDD (pin 1, digital core suppy) of the WM8805. This is pretty good filtering and regulation. This line also feeds PVDD (Pin 11, PLL supply) filtered through L2, and feeds the Toslink module through L1. Good use of ferrites for noise filtering.
The zener regulated line also feeds the DAC, with a simple cap bypass. The 102 resistor you see in the photo powers the LED to show Power-on condition. One of the advantages of the 4344 DAC is that it requires minimal external components. In the case of power, it only has a single power line.
I2S to External DAC
More on the CS 4344 DAC
The CS 4344 DAC is not a very popular DAC among audiophiles. It is used in the Apple Airport Express (the 10-legged device near the center of the photo), a device not always appreciated by audio enthusiasts.
The New (2012) Airport Express changed to a new DAC:
According to RogueAmoeba:
More pertinent to our customers, the audio digital to analog converter is an all-new 24-bit/192khz Asahi Kasei AKM4430. This chip is similar to the Cirrus Logic CS4344 used in the previous model, but should be a improvement over the Burr-Brown PCM2705 used in the original 802.11g Airport Expresses
And also used in the FubarIV Plus [link].
More on the OPAmp
A user reported changing the opamp to a AD8656 with great results. The AD8656 is also a recommended component of the Gamma-2 DAC and it can be used to drive headphones directly. The OPA2209 is also another pin-compatible rail-to-rail opamp with even better noise specification than the AD part. It is used in TPA’s Trident shunt regulator.
|Input offset (max)
||9 mV||0.25 mV
|Input Voltage Noise Density
An excellent report on the device with high resolution photos (very nice photos), extensive measurements and listening impressions [link].