Oppo 103 Mods and Linear Power Supply Updates for 103/105!
I have been working on a LPS (Linear Power Supply) to replace the SMPS (Switch-Mode Power Supply) found in the Oppo BDP 103 and BDP 105 players. Most DVD/Blu-Ray players use SMPS supplies, due to their efficiency, low cost and ease of mfr. The SMPS provides high-current, low voltage supplies and multiple voltages easily and cheaply. They also generate RFI (Radio Frequency Interference) at the switching frequency of the supply.
Every since we first modified the early Pioneer DVD players in the late 90’s and early 2000’s, I have always thought that it would be IDEAL to replace this SMPS with a LPS designed around separate analog and digital transformers.
Well, a considerable amount of time has been spent on this. I found that the current demands were MUCH higher than expected (as high as 6A at 5V; 3A at +15V). This required a pair of 56VA transformers JUST to meet the current demands. There was then the matter of how to deal with heat dissipation. Not large voltage drops, but HIGH current still means a lot of power dissipated by the equation P = V*I (Voltage x Current).
Dr. Lee of S. Korea had designed a LPS for the Oppo’s that used AL angle as heatsinks, that are designed to conduct heat to the floor of the enclosure. I admittedly pursued the same path, as it is the ONLY logical way to reject heat. I used the widest angle I could find, to maximize surface area between chassis floor and AL angle heatsink. I even applied conductive heat grease.
I finally had a design that provided clean voltage at the desired current. It BARELY fit in the unit, but it did fit. I then did extensive listening, primarily with the Oppo BDP-103, because the 103 relies on the SMPS for digital (5V), processor and Video (5V), Motor/control (+15V) and analog Audio (+/-15V). I compared the results directly to that of the SMPS alone.
I then compared the 103 with LPS alone, first, and then with the mods that I had planned, to a STOCK Oppo BDP-105.
Note: BDP 105 = $1200 MSRP; BDP 103 = $500 MSRP.
Note Also: BDP 105 has a linear power supply for DAC and audio circuits, in addition to SMPS. BDP 103 has only SMPS for all functions. Both units have the exact same video and processor PCBs.
1) The LPS is a NO GO in the 103. It runs too hot and the sonic benefits were simply not what I expected. The enclosure is sealed, so there is no good way to reject heat. Mr. Lee has designed a LPS that may be used in the unit. I have tested and installed a ‘Lee’ LPS and it is a good design. However, if you add Lee’s LPS to a unit that we have modified, it WILL void our warranty. I simply feel that the LPS generates too much heat for the 103.
2) The LPS in the 105 I have looked at extensively and decided the following:
A) It ONLY provides 5V supply to the processor board and +15V to the drive.
B) Despite the fact that the unit is passively ventilated, it already runs warm and I am concerned about heat.
C) The LPS would put two transformers right below the MCH audio board and I would be concerned about EMI and other noise contributions.
D) Ultimately, due to my findings with the 103, I have decided that the LPS for the 105 is simply not going to provide a worthwhile benefit and I am not willing to add the risk of future reliability issues, due to excess heat.
3) I listened to the 103 with LPS and SMPS and found VERY little difference. I also measured the digital out signal and found no measurable difference.
4) The 103 stock is NOT as good as the 105 stock! The 105 is MUCH BETTER!
5) The modified 103 (without LPS), but with upgrades to shielding, damping, parts upgrades in analog stage and power supply is much better and closer to the performance of the stock 105, but I would have to give the edge to the stock 105.
I have decided that we will offer a $500 mod for the 103 that will include the following (2CH only):
Power Supply upgrades to stock SMPS.
Chassis damping and shielding.
Upgrades to analog stage (eliminate all coupling caps).
Upgrade IEC to Furutech Cryo-treated IEC.
I am still tweaking a couple of things, but I first had to make a decision about the LPS. I have not compared the two units strictly as transports, but would expect very similar results. In both units, the digital out circuit, on the processor board, is powered by the SMPS. This includes audio coax and optical out, as well as HDMI for video. Both 105 and 103 use the same processor board and video chipset, powered by the same SMPS (Power Supply) design.
Our mods for the 103 are intended to improve its use as a player primarily. The damping, shielding and power supply upgrades will provide some improvement to its use as a transport and for video.
Thanks guys, it has been a bit of a journey here and the results of the LPS surprised me, but I refuse to offer an upgrade that I do not feel is worthwhile and also that I am not confident of its ultimate reliability.