Join Date: Aug 2011
Location: Budapest, Hungary
SAA7321 DAC mods?
I have a Philips CDF-100 (http://www.icdia.co.uk/related/photocd/pcdplayers.html#cdf100
) a combined photo cd - audio cd player which is now my main stuff. Probably not high-end, but it is better than you'd think at first sight. It uses manual loading CDM-9 mechnism, and equipped with SAA7310-SAA7321 bitstream DAC. This machine is really compact, so there is no room for extensive mods, but I decided to do some easy, yet benefical conversions. First I installed some os-cons right next to the DAC, the power supply is detachable from the player and it uses a wall adaptor to produce 8V DC, then a switching supply produces +/-5V for the whole player; the +5V rail is directly controlled by the supply no further regulation, but the -5V rail has a 7905 regulator, I'll try to replace this with a good analog supply..
I want to replace the output opamps with better ones (like TLE2072). Looking at it's service manual I noticed that there are some opamps integrated inside the SAA7321 as well. Have anyone already tried to eliminate these internal opamps, and using better external ones instead? Looking at the datasheet of SAA7322 (~same as SAA7321) it is pretty sure that the two circled opamps 7350 C-D could be omitted but what about the I/U converter integrator opamps? The schematical diagram of the IC shows an internal capacitor, could I calculate it's value somehow from the other known parts of the circuit, or just let alone?