Posted 29th March 2010 at 02:33 AM byquanghao Updated 29th March 2010 at 03:16 AM byquanghao
INTRODUCTION
After the good result obtain with the DAC End I have design with Nguyen Quang Hao a set of boards to create a cheaper project with a sonic performances very near.
The No Oversampling DAC give a more natural sound but if you ear the TDA1541 and TDA1543 seem to lose details.
The AD1865N-K with passive I/V give a perfect combination, natural sound and all the details.
The AD1865N-K give the better performances with a 200ohm MK132 Caddock as passive I/V.
In this configuration the output signal is too low to drive any amplifier so I have design for the AD1865N-K the better output stage.
This DAC use a single ended vacuum tube amplifier without the expensive output transformers used in my original DAC End.
The DAC board follows the original design but has been inserted a jump to switch the phase of output signal.
In any vacuum tube stage the signal on the anode is in out phase...
Posted 27th March 2010 at 07:40 PM byBas Horneman (Bas Horneman's diyAudio.com blog)
Updated 14th February 2011 at 07:51 PM byBas Horneman
The Takman resistors have thick copper wires. This makes for wonderfully strong little spiders.
I've also used ceramic terminals strips for the first time and it makes for a nice strong construction.
And I did the ccs for the phase splitter a while ago.
[edit] I used silver solder. But found out that it is NOT necessary with these fakes. Fake or not it make for a great construction.
"TEKTRONIX CERAMIC STRIPS, HISTORY and GENERAL INFORMATION
Tektronix first developed and used ceramic strips in their oscilloscopes in 1952. During the manufacturing process, silver in liquid form is painted in and on the notches of the strips prior to the application of the final glaze and final firing. The silver is then firmly bonded to the ceramic and wires can be soldered directly to the ceramic.
Special silver-bearing solder should be used when soldering to ceramic strips so the silver bonded to the strip does not...
Tonight I found out it is a really good idea to ground the shaft/body of the rotary switch in order to eliminate pick up of 60Hz and its harmonics. I noticed moving my hand closer to the metal knob on this switch resulted in a >20dB increase in 60Hz spectra and the addition of somewhat lower level harmonics at 120Hz, 180Hz, and 240Hz.. I grounded the switch with a piece of 28ga wire between the lock washer and the body of the switch and grounded it to the board ground. This totally eliminated any pick up with no noticeable line frequency or related spectra. (My case is totally shielded on the top and bottom, but not sides, front or rear - and does not appear necessary to do so.)
