Archive for November, 2009

hp 3478A Multimeter

Friday, November 13th, 2009

This is a very old 5.5 digit multimeter with first production in 1981 or early.  You can find this meter easily on ebay for $100 to $150 USD which is a real bargin for such a good multimeter.  I use this meter most often for voltage and current measurement.  For audio signal, this meter can easily give you a accurate AC level reading up to 100kHz.  I think this is the “must own” meter for diyer due to it low cost and high performance!  I have two of this.

HP 3478A Technical Data

Some internal photo of hp 3478A:  This is a well design and well built unit even it is a low cost version!

New FFT measurement for Yamaha DA202, DA2X and TDA1541 SZ DAC

Thursday, November 12th, 2009

Please go back to Yamaha DA202 and DA2x for FFT measurement on Nov 12, 2009.





Friday, November 6th, 2009

Update on Nov 6, 2009:

Please look at the document below “Upgrade from D1V3 to D1V33“.  This is a worth while upgrade for the jfets to K369BL.  The major impact is that the input impedance of Jfet IV will be half which is estimated to be about 12 ohm while original D1 is about 10 ohm. The final result can be easily observed on the sonic improvement of the sound!

Project completed on Nov 11, 2007:

This is D1V3: Please refer to D1V3 Assembly Manual for details.


D1V3 Silk Top

D1V3 PCB Dimension

D1V3 Circuit Diagrams


D1V3 Assembly Manual

Upgrade from D1V3 to D1V33

Some discussion in forum:

D1V3 with AD1862 20bit DAC

Wednesday, November 4th, 2009

AD1862 is a 20 bit R2R DAC made in the same period of PCM63 by Analogy Device.  This chip size is small using DIP16 package.  The performance of this chip is also outstanding but this DAC was not so widely used in CD Players relative to PCM63 in the past.

To use this chip, the DAC analogy supply of D1 need to be at +/-12V and the digital supply can be remained at +/-5V in the D1V3 or D1V33 board.  To change the analogy supply to +/-12V, 4 resistors has to be remove and re-solder from 300 to 850 ohm (I use 750 ohm + 100 ohm).  The designation of the 4 resistors are R105, R109, R126 & R127.  Besides the resistors change, the capacitors of the analogy supply has to be ensure using 16V or above capacitors.  I have 8 pcs 6.3V blackgate on the board and thus I have to change them to 22uf 16V Duorex capacitors.

Since AD1862 is not pin compatible with PCM63 and thus I have to hard wire 4 converter boards as shown on the pictures.  The pins that connect to PCM63 sockets are Pin 2, 6, 7, 11, 12, 13, 18, 20, 21, 28.  The two E-caps (1u and 12u) on the board is for AD1862 filtering and Red wima is 0.1u for power supply decoupling. This is a bit time consuming but it is a cheap way to test out how AD1862 perform in the D1 platform.

The result is quite satisfying as the AD1862 also sound very good.  It has darker sound due to its strong bass (good current source driving capability using +/-12V supply).  The distortion is also lower compare to PCM63 in D1 platform due to its lower +/-1mA output range.  Noise floor is better than PCM63 a bit (1~2db) as seen in the FFT measurement.  But there is more high frequency odd harmonics when input is at 20bit/44.1k at 0 or -80dbFS.

All measurements are in balance output mode unless otherwise specified.

FFT DAC D1V3 AD1862 vs PCM63

FFT DAC D1V3 AD1862 @ -80dbFS 16 vs 20bit

FFT DAC D1V3 AD1862 Single end output

FFT DAC D1V3 AD1862 Balance output 0dbFS log

D1V3 & D1V33 upgrade to 96k Fs

Tuesday, November 3rd, 2009

 Since the SM5842 can only receive signal with maximum Fs at around 48kHz, it is not possible for D1V3 and D1V33 to receive 96k signal.  Due to that I have find one solution to do that using a AD1896 (or SRC4192) ASRC below.

DIR9001 –> AD1896 + 11.2896MHz XO –> SM5842 –> PCM63.

With above configuration, the input Fs can be from 32k till 96k while the output Fs from AD1896 is fixed at 44.1kHz.  AD1896 is set to Async mode with slave input mode and master output mode.  Both AD1896 and SM5842 is using master clock from the XO at 11.2896MHz.  Thus the jitter at SM5842 XTI will 100% depend on the quality of the XO.

Of course I can use a XO frequency of 12.288MHz to have a ouput Fs at 48kHz but I do not have this XO frequency on hand.  With higher Fs and later 8x over sample in the SM5842, the output noise after Jfet IV with single pole filter will be minimized.

Here is the picture of my implementation: