The unit was further tweaked in its power supply by replacing all diodes and capacitors, but let's just stick to the analog board for now. The following modifications were carried out:
Onboard regulators were replaced with NewClassD's Ultra Wide Bandwidth regulators;
Onboard opamps (Burr Brown OPA2134) were replaced with NewClassD's Discrete opamps;
Onboard electrolytic capacitors at the output stage were replaced with Mundorf's M-Cap polypropylene capacitors;
Onboard electrolytic capacitors that fed the DACs (with a capacity of 100 microfarad) were replaced with Nichicon capacitors with a capacity 33 times greater (3300 microfarad, like those you can find on Krell's Home Theater Standard 7.1 preamp processor);
Other onboard electrolytic capacitors were replaced with Wima MKS2, and Nichicon capacitors where appropriate.
As promised, I'll throw in a few more details concerning my friend's mod and the benefits therefrom.
His first modification involved replacing the Pioneer's onboard opamps with Burr Brown's OPA627, said to be the best opamps currently available for audio purposes. Together with the OPA627, he replaced capacitors on the signal path with Wima MKS2, and capacitors at the output stage with Mundorf's M-Caps. I could hear the benefits of this modification when I was lent the player and could test it in my audio setup, and wrote about it on this very forum. The BDP-LX91's onboard opamps, Burr Brown's OPA2134, are very mellow sounding but lack dynamic aggressiveness and bass articulation (the latter being a peculiar characteristic of all opamps, though some are better than others in that area). The OPA627 performed a lot better in terms of dynamics and detail, while still lacking texture, richness and articulation overall. The new, better quality capacitors, on the other hand, made for a smoother treble and finer detail.
Second-base was replacing the OPA627 with NewClassD's Discrete opamps. This was done after a direct comparison with my modded OPPO BDP-83SE, when my custom discrete components circuitry proved itself superior to the opamps. NewClassD and Burson Audio both offer a discrete opamps solution, the latter requiring a much more robust power supply to be run (a friend of ours is modding their BDP-LX91 with Burson Audio discrete opamps, so we should be able to run a direct comparison in the near future). NewClassD's discrete opamps gave sound a LOT more texture and detail, and a LOT more bass articulation and output. A new direct comparison with my modded OPPO revealed the latter still had an edge on bass reproduction, whereas the Pioneer exhibited finer detail on the medium and treble portions of the sound spectre. As a matter of fact, the amount of additional sound information revealed by NewClassD's Discrete opamps compared to Burr Brown's OPA627 was astonishing, and bass tightness and articulation improved dramatically. What was missing was some more punch, as the new opamps apparently required more energy to fully manifest their capabilities.
The final move was replacing the onboard regulators (classic models 7805 which can be found on most commercial audio players) with NewClassD's UWB regulators, and the capacitors feeding the DACs with higher capacity ones. Regulators serve the purpose of drawing current from the power supply and feeding it to the analog circuitry, regulating de facto its frequency and ensuring they get pure 50hz/60hz current. Like opamps, they are quite sensitive to noise and exogenous interference, and 78XX/79XX regulators are especially bad at rejecting noise. NewClassD's UWB have a very high noise rejection capability and provide circuitry with a much cleaner current, thus enabling the DACs to express their full dynamic range. This, paired with higher capacity caps to feed the DACs (specifically, Nichicon 3300 microfarad caps), proved to be the most outstending step in the Pioneer's mod. Separation between different sounds and intruments in music reproduction is now so marked, there is full-blown silence between them. The dynamic range is full, and allows to go from complete silence to end-of-world bombastic explosions in no time - we tried this with Michael Jackson's This is it bluray concert, the track was Thriller. After a calm, instrumental part with keys it suddently went BOOM and my friends and I were looking at each other, grabbing the sofa with our eyes wide open. No joke. Regulators and DAC-feeding capacitors were the biggest step, and provide the cleanest sound I've ever heard.
This also proves the biggest limit in today's machines aren't the DACs. Having newer DACs with a SNR 2db better and lower THD when human hearing is already incapable of capting distortion below the threshold of 0,1% is perfectly useless. The Pioneer's Wolfson DACs are at least two years old now, if not more, yet have all the dynamic range and sound clarity you may need, if the rest of the circuitry allows them to manifest it. Of course, the better the DACs, the better the end result. But a machine with high quality components and an older DAC will sound better than a machine with a lousy analog board and newer DACs.
I'm sorry I couldn't provide with more details but it's kind of hard to put music and sound to words. It has to be heard, to be understood |
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