Monday, September 22, 2014

An Easy OPPO BDP-105 Modification

I have owned an OPPO BDP-105 for over a year now and have appreciated its fine quality especially when it came to NOT sounding like the typical digital music player. Right out of the box its strengths lie in excellent resolution and inner detailing heard only in the finest of the dedicated DACs available at the time. But one day, I was over at a friend's house listening to his Bel Canto DAC and quickly realized the shortcomings of the OPPO's Sabre 32 DACS. The Bel Canto was extremely silky with a level of sophistication that sounded more realistic, especially in the pianos we were listening to through his Martin Logan speakers (yes, the big ones).

This experience got me thinking: Phil, you haven't tried modifying your OPPO yet and the warranty is not behind you. WHAT ARE YOU WAITING FOR? 

With a quick perusal of the net for off-the-shelf modifications, people providing these mods described their changes and their results. Some focused on the analog output section (which I agree does need some work) and others on clock jitter (again, no argument here). But I'm the sort of dude who likes to get the most bang fro the buck and so I focused on two things: ground loops and the power supply.

The OPPO designers used an old-school approach to grounding whose philosophy goes something like this: Since the chassis is grounded, and since you need to attach a ground at every circuit board, use the chassis as a wire instead of running another wire back to the power supply. Such a philosophy saves a few pennies and imposes huge, clearly-audible problems. But further investigation of the grounding scheme proved to be futile since not only did the BDP-105 use screw connections to the chassis for PC board grounds, it used multiple ground traces everywhere on the PC Board adding what appeared to approach an infinite number of them.

The only solution for a design of this type (a non point-to-point design) is to cut traces on the board (as I did in my Dared MC-7P mods) and since I did not want to take the time to analyze what needed to be cut and what needed to be saved, I chose to only move the ground wire from the incoming power cord to the PC board screw closest to it. One problem down but I did not anticipate that doing this would yield huge sonic benefits. On to the next stage of mods.

In my web search, one of the things I found many of the folks doing is to change out the power supply diodes on the analog board to a fast-recovery and low-reverse-leakage-current (FRED) type. Frankly, I have never experimented with such diodes even though a friend of mine swore by them. So with a quick search at, I found a few that seemed like they would do just fine. The only issue was that they are tens of amperes in capacity as opposed to the tiny one ampere capacity diodes currently used. No matter, in this case, the 10-amp capacity TO-220-2 case did not impose a physical real-estate related problem despite the fact that eight diodes needed to be replaced (D19, D18, D10, D12, D16, D17, D15, and D14). Everything fit nicely by using the leads from the old diodes to which I soldered the legs of the new ones.

OPPO BDP-105 PS Diodes

Now comes the acid test: how does it sound? Well, let me say this to give it all away: you gotta do this mod! I have always thought that the OPPO had a huge hidden potential and from my modding experience I suspected that it was an issue in the analog output stage (most likely the op amps and the output capacitor). But what these diodes do to clean up the background noise and permit the existing circuitry to operate more effectively is in a word JAW-DROPPING (OK, two words).

Everything, and I do mean everything, is literally better. Inner detailing, noise floor, sound stage size, transient response, tonal balance, strain, anything you can think of in the way of assigning an adjective to a flaw is seriously reduced. While more could be done to make this unit sound better, IMHO this is truly the single most cost-effective thing you can do to bump up the quality of the sound. I know that these diodes cost 10x more than the ones currently used (6 cents vs. 60 cents or less than $4 total) but the benefits are huge.

Sibilance issues I originally suspected where in the crossover network were in fact issues with the power supply in this audio section. Issues with time alignment (acoustic phasing) in the loudspeakers were actually issues with the power supply. And with the addition of the new Teflon bypass capacitors to the tweeter and super tweeter signal-path capacitors in my crossover network, I have never been more blissfully happy listening to music than I am now - and that is saying a lot since it is so hard to impress me!

Now I am looking with this same level of serious suspicion at the diodes in my power amp, preamp, and the phono pre-preamp. I can only imagine what blissful benefits can be achieved by simply swapping these diodes out too.

If you want me to perform this mod on your OPPO, email me at
philip at okstatealumni dot org

See also the next jaw-dropping modification you can do at

Yours for higher fidelity,
Philip Rastocny

Skeptics are essential to keep us sane; skeptics do little to keep us inspired. Philip Rastocny, 7-16-2014

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