Meridian Unplugged - Powered by MrTechGuy.co.uk Forums Discussion HiFi & HT Chat Meridian 861 + 621 + OPPO 93 users: Advise Please

Of course HDMI is needed for video, but my thoughts were that keeping it away from the audio processor would be a good idea.

I'm quite a strong believer in having one unit do one job:

Playing in the player
Audio processing in the audio processor
Video processing in the video processor
Amplifying in the amplifier
etc

For what it's worth I just spoke to an engineer at Oppo's technical department. According to him there are no audio or visual benefits to be gained from trying to split audio and video by using the two HDMI out puts on the Oppo 93 unit. The two cable set-up, according to him, is for people who have a 3D display but who also have an AVR that can't pass 3D. Bob Pariseau over at AVS confirmed the same. Based on this I'm going to use a single HDMI cable run to the HD621.

I understand but having a Blu-ray player that combines video and audio processing plus HDMI doesn't appear to fully separate the two as your seem to acknowledge. You're still left with an audio processor feed from a device with all the video nasties.

I assume from your comment below that the claim that SQ suffers is due to noise propagation(?) if just by connection to a device that passes video other interface type are affected ?

"I found that simply having the HD621 connected caused a degradation to the SQ of a system that was configured to use SPDIF connections. You can't get away from the impact of all that with BD playback, but it still showed how SQ suffers when digital audio and video aren't fully separated."

Avii

That makes sense since both HDMI's simultaneously output audio and essentially the same video.

One solution to establishing if there are perceivable differences that some may continue to claim is double blind listening assessment in a properly setup and calibrated system.

Avi

I do not challenge the findings noted above but I suppose that, naturally enough, they were not factoring in the effect a HD621 would have.

I would have thought that taking the (claimed by Oppo, superior) HDMI 1 output direct to a display would give a better result that via a HD621. We have been told that no video-improvement processing takes place in the HD621. Therefore the direct route escapes the extra connections and potential electrical interference of the HD621.

On the other hand, feeding the HDMI 2 output to a HD621 strips out the audio, upsamples, and appodises to give MMHR, which can only be a considerable advantage.

Please could you explain this further. Are you talking about a system such as a BD player (eg Oppo 93EU) connected to a processor (eg 861v6) via SPDIF using a DSP such as Direct? And that by having a HD621 connected (turned off?) this degraded the sound?

Its your use of the term "simply having the HD621 connected" that is confusing me, but I don't want to read too much into a mere form of words.

Thanks

In an end to end digital display chain I don't think the HD621 will make any difference to the video data. If it has a higher HDMI tolerance it may improve aspects over longer cable runs.


The same process applies if feeding "HDMI 1" to the HD621 i.e. the video is separated and the audio processed.

I think the original question was is there a demonstrable audio or video improvement with the Oppo 93 of using "two" HDMI ouputs i.e. one for video and one for audio (although this is also contains video). It appears the answer maybe no in practice beyond perhaps comms issues but maybe the "thought" that it would will offer a psychological benefit.

Avi

here is what i found that Audiocom does to the BDP-93

Oppo BDP-93 Modifications

The starting point for our BDP-93 mods was to improve the switching power supply. The parts selected for the task are based on delivering the optimum impedance, ESR, capacitance value at each circuit node, bypassing and decoupling. A capacitor has a ripple voltage (seen as noise on the supply voltage) proportional to the ESR of the capacitor. By selecting the best grade low ESR capacitors we drastically reduce ESR which results in lower noise.

Step two was to improve the player master clock. The Oppo BDP-93 has 4 clocks, but we are only concerned with the �master clock� for the core processer, the OP8531 chipset. The OP8531 has a built-in �Pierce Oscillator� (inverter gate) the external quartz crystal provides the required clock frequency. This type of oscillator is simple to implement but has the worst arrangement for high phase noise, jitter. The Pierce Gate receives noise from the hundreds of switching processes of the OP8521G chipset which is transferred to the output of the clock signal. We replace the Pierce Oscillator with the Superclock 4. With the OP8531 referenced to an ultra-low jitter external clock jitter is significantly reduced with significant improvements to all video, audio formats and video and audio outputs.

The clock will only perform as well as the power supply that feeds it, less power supply noise in this case = less phase noise. To achieve the quietest power supply performance we installed a Bybee Music Rail� following a regulator output. This is a compact device which reduces signal and power supply noise up to 45 db, achieving limit to the noise floor of 20 nV per root Hertz.

More information available soon.

Detailed list of upgrades included, additions and changes are highlighted:-

Oppo BDP-93EU HDMI Level-1
■ Furutech FI-10 IEC inlet.
■ Upgraded electrolytic capacitor for HT power rail.
■ Upgraded electrolytic capacitors for LT power rail.
■ Upgraded electrolytic capacitors for bypassing 5V digital power supplies. (video processing)
■ Upgraded electrolytic capacitors for bypassing 15V digital power supplies. (BD Drive)
■ Upgraded power supply capacitors for decoupling (main PSU).
■ Superclock 4-S ultra-low jitter master clock.
■Sontech resonance control for lid.
■ Kimber Kable internal wiring.

Oppo BDP-93EU HDMI Level-2

■ Furutech FI-10 IEC inlet
■ Bybee Slipstream Purifiers for AC input.
■ Upgraded electrolytic capacitor for HT power rail.
■ Upgraded electrolytic capacitors for LT power rail.
■ Upgraded electrolytic capacitors for bypassing 5V digital power supplies. (video processing)
■ Upgraded electrolytic capacitors for bypassing 15V digital power supplies. (BD Drive)
■ Upgraded power supply capacitors for decoupling (main PSU).
■ Superclock 4-S ultra-low jitter master clock.
■ Bybee Music Rail� for clock power supply.
■ RF absorbing techniques are employed in key locations.
■ Kimber Kable internal wiring.

http://www.audiocominternational.com/product_info.php?products_id=225

Do they provide detailed measurements of the before and after difference these changes make in key areas ?

Here's an extract from Audiocom about claims they make for the Oppo 83 (they don't mention what video interface is used but given the nature of the player HDMI would be the obvious choice) -

"Clearly, colours were bolder, contrasts between whites and blacks more defined, with deep blacks more inky black, and whites fresher and cleaner looking."

It should be easy enough to measure and compare key image attributes in a video chain calibrated using a stock Oppo. The claimed changes to the video data should measure different (beyond measuring tolerance) if they are visible by eye.

I'm still curious how the mods change digital video data values. Any ideas ?

Avii

I cannot speak about the BDP-93 but, with the Ayre DX-5, there was a distinct difference between the normal (Oppo) HDMI output and the Ayre-designed HDMI output which has only blue-screen video with the latter being better. Both were fed to the HD621/861.

Kal

I assume that's in relation to audio ?

Have you been able to ascertain if "pure audio" mode i.e black-screen HDMI video output makes any difference on the Oppo audio over HDMI ?

Have you measured the key on screen video attributes between the stock Oppo and Ayre ?

Avii

Yes, that's kind-of what I meant, except that switching the HD621 on caused the degradation in the SQ. It added a hashy sound onto the top end. Disconnecting the cables from the HD621 to the controller removed it, as did switching the power off.

Having said that, using the HD621 gave me the best-sounding blu-ray audio that I've heard from any processor.

Nick