Archive for the ‘DAC’ Category

F5T Pre-amp + FDA-2A AD1955 DAC in one box

Sunday, May 11th, 2014

This is a pre-amp plus a FDA-2A in one box.  It was built in year 2012.  I use a old Yamaha DA8X box to house eveythings insides.  See the pdf files at bottom for details.


FDA-2A with USB, Optical and AES digital input.  Push button for digital input selection at the front panel.

DAC direct output is available in RCA sockets.

F5T Pre-amp:

Alps volume control from DAC output and note that there is no other analogy input for the preamp.

The pre-amp is based on Nelson Pass F5T power amp design and striped down to only one pair mosfet and lower bias current at about 200mA.  Supplier voltage is at about +/-23V with a small transformer.  Power mosfet is using Toshiba J200 / K1529 pair and casing is acted as the heatsink of power mosfet.

A headphone jack is connected in parallel with the pre-amp RCA sockets.  It can drive most headphones due to sufficient high bias of the power mosfets.


Details refer to this pdf file: F5T-Pre_DAC



RX-V8 Interface Board from “Amanero USB-I2S module” to FDA-1B or FDA-2A DAC

Thursday, November 1st, 2012
The interface board is used to connect the Amanero Combo384 ( USB-I2S module to FDA-1B or FDA2A with TOTAL Isolation of the power supply and ground for both I2S bus and control signals.
With this interface board and Amanero Combo384 (buy separately from Amanero), FDA-1B and FDA-2A will have a input options of USB with 24 bit/ 192k Sample frequency capability. 

Price is as below:

1. PCB only: HK$100 (about US$13).  (BOM and Circuit will be provided after order)

2. Fully Assembled board (please specify FDA-1B or FDA-2A use): HK$400 (about US$50).

3. Shipping cost will be HK$31 and paypal fee add 5% on top. This will be waived if brought with the DAC kit FDA-1B or FDA-2A.


Jitter measurement with FDA-2A DAC and the result is EXCELLENT:

RX-V8 Jitter


FDA-2A AD1955-WM8805 DAC kit launched now

Friday, September 14th, 2012

Major highlights:

1. Use AD1955 and WM8805 key parts with single end output.

2. Same super sound discrete IV converter used in the FDA-1, & FDA-1B.

3. Natively support up to 24bit/96k with NOS module.  Support 24bit/192k with AD1896 ASRC module (sell separately).

4. Maximum 4 digital input and one I2S input (total 5).  Default control board provided will control total 4 inputs only (either 3 digital + 1 I2S or 4 digital input).

5. Compatible with many USB2.0 24bit/192 modules: Tested Xmos reference design and Amanero USB2.0 to I2S module.  Interface board to Amanero USB2.0 to I2S  module with or without “Isolator” will be released soon.

6. Control bus for AD1955, WM8805 and other signals are provided for future expansion into fully software mode.

7. DSD input bus is provided for future upgrade.

Details in the manual below:

1955V3_1DAC Manual_r1

Go to Store page if you want to buy this kit :


AD1955+WM8804/5 SE DAC – launching soon!

Tuesday, August 14th, 2012

This is a single ended DAC using AD1955 DAC and WM8804/5 receiver.  Here are some photos of different versions:

V1.0: FDA-1B with AD1955 DAC chip hardwired on a SSOP board.

V2.0: WM8804 + AD1955 with 3 digital input and one I2S.

V2.1: WM8804 + AD1955 with 4 digital input and one I2S.

V3.0: WM8805 + AD1955 with 4 digital input and one I2S.

V3.1: To be made soon.

On the V3.0, some jitter is measured and the result is quite good.  See attached pdf document:


Note that there are connectors at both the AD1955 and WM8805 chips for the control bus and thus software mode can be turn on if necessary.  This DAC board is really flexible for future expansion. DSD bus socket is also reserved for the AD1955 (SCLK, DSD-Left, DSD-Right, DSD-Phase).  Thus this DAC board is able to experiment on DSD input and also mono mode of AD1955 if a software controller is available.


WM8804 to CS8412 converter board for D1V3 & D1V33 new upgrade

Monday, July 23rd, 2012

I have sold hundreds of D1V3 & D1V33 few years ago but I have not forgot continue support for this classical DAC using the best R2R PCM63 DAC chips and Jfet IV common gate topology.  There is a new life to the old classic DAC if you upgrade the receiver from CS8412, CS8414, or DIR9001 to WM8804 which many diyers as well as hi-end audio professionals are all agreed to its best sound performance.  Now this WM8804 to CS8412 converter board is available for sales for just HK$250 net (about US$32).  It is fully assembled and tested with no extra shipping and paypal fee.  I believe it is the best news for all D1V3 and D1V33 users as well as other DAC users because this converter board can output 4 digital modes and thus it can meet most DAC technical needs.

16-bit Right-Justified Mode
24-bit Left-Justified Mode
24-bit I2S
16-bit I2S

Please take note that there is a chance that this converter may not work perfectly or even not working in other DAC platform as there is no 100% compatibility due to different chips in different time of history.  But as usual, I shall advise my best guess after reviewing the DAC circuit before you buy and provide remote trouble shoot support as usual.  So take your own risk when using this in other DAC and I will not accept any return unless the converter is DOA.

Technical details: WM8804 to CS8412 Converter Board Technical Details 3

8804_8412 circuit diagram