Selasa, 31 Juli 2012

AD1865 round up

After missing June for writing, now it's time for my recent DIY audio adventures. I've kind of settled now with my DAC, both TDA1541 and AD1865. For the former I have made nice small enclosure and kind of throwing everything inside, except for 5676 DHT pencil tube filament supply, which must be fitted outside and battery powered. Here are some pics.

Bit messy there, with small enclosure of my ex Sony CDP-M75. On the left is the shoebox power supply from a Pioneer LD player for DAC section, middle part from top is a loaner high & low voltage transformer for tube & B1 lightspeed buffer, below that my favorite common gate Jfet I/V and below that the DAC itself, the one that using 74HC04 chip that I find sound best (story here).

On the right hand from top, yup ..that famous lightspeed Pass clone B1 with Silonex LDR, at the middle is the DHT tube stage, 5676 tubes in anode follower topology. Like this AF better than the cathode follower, especially with 'slower' AD1865 dac. At the bottom is the B+ supply for tubes. Black round thing is a rheostat. With this I can change B+ on the fly, while watching 1kHz spectrum with Visual Analyser & of course to find by ear that famous sweet spot ...and..poof! Nelson Pass said :)

I have 2 outputs here, direct from tube or from B1 buffer. From DAC current out goes to Jfet I/V, to the 5676 while another leads from tube out goes to B1 buffer. Output voltage of the I/V is set so low that the tube out gives 3Vpp since the AF tubes gives bit of gain, enough kick to drive my Aleph J clone direct from DAC with B1 volume control.

 Battery for heater

 Black anodized, Pass style face

That sweet sounding little DHT 5676 tubes

My other project is to have a full solid state pre amplifier that I always wanted to have, but this is for next time ;). Here is a teaser : Jfet version of John Broskie's famous Aikido. Not an easy project, believe me, tube version is easier. Until next time & thanks for reading

The 'AikiFet'