So I decided yesterday afternoon that it is indeed high time I put the AD815 line driver preamp together , I bought this board with an AD815 chip from Rudi months ago , when we were all building his MM phonostage .
This a Walt Jung concept tweaked by Rudi who also added an ultra-quiet regulated PSU . https://www.diyaudio.com/forums/attachments/analog-line-level/474914d1427811017-walt-jung-circuit-analogdevice-pdf
Where Rudi started developing this board : https://www.avforums.co.za/index.php/topic,9931.0.html
Here's an image without the Heatsink attached .
The tracks on this board are super close together , takes for some insane soldering especially if you have a blunt tip .
If it wasn't for my good supply of liquid flux , all those parallel tracks would still be soldered together ,
After washing the flux from the board I was quite happy to see the tracks no longer connected . Excuse the hair .
I first hooked up the wrong transformer , because the schematic I have is marked 15 V AC , and this pathetic little 6-0-6 trafo was the closest thing I had handy .
The pre was not sounding good , and I was getting up to 32mV DC on outputs , depending on what opamp I was inserting . The pre has to take a FET input opamp , OPA2134 being the one recommended by Rudi . With the wrong transformer connected the regulation was not functioning , in fact the entire pre was barely functional . A call from Rudi set me straight regarding the correct transformer , just before I started putting a gaint Russian 1uF cap on the output , or start fault finding where there is no fault . :Ooooooh:
I have a lekker selection of opamps that I've collected over the years to try .
As soon as I connected the correct value transformer - 15-0-15 - everything snapped into place . No more background noise , no more DC on the outputs , just sweet , magical , beautiful 3 dimensional sound . Absolute clarity , with amazing imaging (no :cr@p . Music has astounding depth , height , width and bloom - incredible !
Here , my plankie with standard OPA2134 as prescribed by the man .
This a Walt Jung concept tweaked by Rudi who also added an ultra-quiet regulated PSU . https://www.diyaudio.com/forums/attachments/analog-line-level/474914d1427811017-walt-jung-circuit-analogdevice-pdf
Where Rudi started developing this board : https://www.avforums.co.za/index.php/topic,9931.0.html
Here's an image without the Heatsink attached .
The tracks on this board are super close together , takes for some insane soldering especially if you have a blunt tip .
If it wasn't for my good supply of liquid flux , all those parallel tracks would still be soldered together ,
After washing the flux from the board I was quite happy to see the tracks no longer connected . Excuse the hair .
I first hooked up the wrong transformer , because the schematic I have is marked 15 V AC , and this pathetic little 6-0-6 trafo was the closest thing I had handy .
The pre was not sounding good , and I was getting up to 32mV DC on outputs , depending on what opamp I was inserting . The pre has to take a FET input opamp , OPA2134 being the one recommended by Rudi . With the wrong transformer connected the regulation was not functioning , in fact the entire pre was barely functional . A call from Rudi set me straight regarding the correct transformer , just before I started putting a gaint Russian 1uF cap on the output , or start fault finding where there is no fault . :Ooooooh:
I have a lekker selection of opamps that I've collected over the years to try .
As soon as I connected the correct value transformer - 15-0-15 - everything snapped into place . No more background noise , no more DC on the outputs , just sweet , magical , beautiful 3 dimensional sound . Absolute clarity , with amazing imaging (no :cr@p
. Music has astounding depth , height , width and bloom - incredible !Here , my plankie with standard OPA2134 as prescribed by the man .
