chefsinc Posted April 7, 2014 Posted April 7, 2014 Recently I have been experimenting with my cd players once again. I have 2 marantz cd5000 in which sits the venerable Philips TDA1549 which is a dac chip as rare as hens teeth. In this Philips based cd player sits a digital volume control and normally a standard ic op amp for analogue stage. A couple of years ago I upgraded and modified these Marantz cd players with discrete op amps and jantzen capacitors in the analogue stage as well as new capacitors in the digital power supplies. This brought a marked improvement over an already great sounding stock player and I was happy to compare it with some great high end cd players as it seemed to hold it's own. After Lukas Fikkus's suggestion that this DAC chip has enough voltage out to drive an amp I by passed the analogue stages and I connected the dac chip up to the RCA outputs via Jantzen silver caps. Wow what a difference, I run the output directly to the modified version of a Marantz pm7000 power amp section only by passing the pre amp section entirely and use the cd players digital volume control to vary the spl. I am amazed at how much better it sounds and to be Honest I kind of like it better than my Musical Fidelity a3cr pre amp and power amp setup with an Audio GD dac being fed by a digital only Pioneer avi989 dvd player as the transport.(removed the analogue stage and power supplies) very clean, great bass control and crystal clear midrange and treble. very happy to say that I will not be looking for an upgrade in the future and am now considering bypassing all the pre amps in my systems with this method. I also have a Sony cdp308 esd that has been clocked and discrete op amps and jantzen poly caps in the output stage. The Sony is a different kettle of fish and must run through the analogue stage but it also has a remote volume control and variable output and direct into a power amp brings this tired old bird to life once again. A tube stage may add some benefit to the Sony but with the Direct DAC to power amp of the Marantz cd5000 I am in heaven. regards Jonathan 1
Telecine Posted April 7, 2014 Posted April 7, 2014 Thanks for the great post. Do you have a bit more information about what you have done to the Sony? I have one lying around and would be interested in what upgrades you have performed and any improvements found as a result of them.
chefsinc Posted April 7, 2014 Author Posted April 7, 2014 Hi Telicine, The old bird has had a lot done to it but not what could be done, If we added some discrete power supplies to the DAC chips I think it would be an improvement also. what I did to mine was remove the stock standard ic op amps and replace them both with dual audio gd discrete op amps, replace the capacitors to larger better quality power caps, new film caps in the analogue output stage, and added a new audio GD clock. this was the biggest improvement, once i added a seperate dedicated power supply to it. I woud be happy to guide you through the process if you like. as i have all the parts to do it again for another one i had but i shelved that after i fried the board accidentally (stray solder).
georgehifi Posted April 7, 2014 Posted April 7, 2014 Wow what a difference, I run the output directly to the modified version of a Marantz pm7000 power amp section only by passing the pre amp section entirely and use the cd players digital volume control to vary the spl. regards Jonathan Going direct with a cdp that has digital domain volume control into poweramps is always going to yeild a more transparent sound, so long as you can get the volume you need, which 99% of cdp's with volume can do with no problem. Some people though, like the colouration that certain preamps give, that's why they all sound different, because each one has it's own colouration, and you can get on a merry go round with them. Jonathan I hope you left the Cext2 cap in, as this is a part of the internal output buffers feed back, that will roll of the HF. Cheers George
chefsinc Posted April 8, 2014 Author Posted April 8, 2014 Hi George, I did do that, I picked up the analogue signal from the 47uf filtering capacitor before it went into the op amp.
georgehifi Posted April 8, 2014 Posted April 8, 2014 This is a thought also, measure pin 7 in the above bock diagram I posted to ground for any dc offset, if below a few millivolts dc, take your output from there to the rca's, and get an even better sound with no coulping caps at all in the signal path, just be carefull to turn on the cdp first and off last, as it may have strong switch on and off thumps if the power amp is on. Cheers George
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