Update in May 2015

May 31st, 2015



Sept 2014


May 2015

In May, I have moved back to my own apartment in Singapore and now I am doing some minor renovation myself (DIY).  Now unpacking my boxes and found I lost one box No. 6 which I have not identify what is inside the box yet!.  I am painting the walls and after done, will start to set up my lab again at this location.  More to come in June 2015…


Update sales for Toshiba 2SK170 and 2SJ74

March 15th, 2015

Dear all buyers,

Please be note that the stock is running low and there will be no more offer for K170/J74 matched for sell effectively immediately.

Parts that is still available is J74 match pair or quad for Idss >=9.6mA and K170 match pair or quad for Idss =<7mA (limited stock).


Thank you for all your support.

Spencer Cheung

15th Mar, 2015.


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

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



Sale for this month (May 2014)

April 21st, 2014

During last week, I manage to have a short trip back HK for few days.  Thus I have limited time to sort out the kits for sales.  Here is what I can offer at this moment.

1. F5T kit A or B in the list.  Total 1 kit A OR kit B is available.  Note the jfets and mosfet are with updated prices.


Link of kit: http://www.fetaudio.com/archives/1725


2. FDA-2A AD1955-WM8805 DAC kit is only available for 2 sets.  HKD$1550 each.

Links: http://www.fetaudio.com/archives/1666


3. Toshiba K1530 / J201 pairs (not match).  This single pairs is good for bulding a mini F5T as a headphone driver.  Offer price is same as old price at HK$100 a pair.  Shipping and paypal fee are additional.


4. Toshiba Jfets K170BL and J74BL is still available and price refer to below announcement.


That is all for this moment. Thank you.

Sales Announcement Update

February 15th, 2013

Date: Revised on 23rd Mar 2014

Toshiba 2SJ74BL and 2SK170BL match pair for sales: (NEW PRICES from 1st Nov, 2013)

  1. 2sk170BL/J74BL match pair HK$120/pair (Pair = K170 x 1pc  and J74 x 1 pc)  (about US$16). Idss 6.4 to 9mA only.
  2. 2SJ74BL : HK$160/pair (about US$22 – 2 pcs) or HK$320/quad (about US$44 – 4 pcs). Idss 6.4 to 11mA.
  3. 2SK170BL match quad : HK$100 (about US$13 – 4 pcs). Idss 6.4 to 9mA only.
  4. Note that Idss of K170 at 10mA and above is basically not available.  If found, the price is HKD$100 each.
  5. Unmatch will be same price as match above.  Only BL grade of above jfets are available.


Shipping is HK$35 (US$4.5) to worldwide by registered airmail and paypal fee 5.5% (4.5% for purchase amount >= HK$500). All matched within 0.2mA Idss @ 10Vdc.  Maximum match is 4 pcs K170 and 4 pcs J74 with same idss match together in one group.  Note that the temperature at measurement is about 28 to 30 degC in Singapore.

There is further delay for the sales of other kits and parts.  Tentatively it will be by 2nd half of 2014.

Thank you for all the support.