Meridian Unplugged - Powered by MrTechGuy.co.uk Forums Discussion MQA - Related technology, products and music Multichannel MQA

Until the release of Bob Stuart's Q&A session on MQA published in Computer Audiophile on 4/7/2016, it was certainly not clear to me how they were correcting for the impact of both the "gateway" a/d and d/a digital filter errors in the MQA digital ecosystem. In the article, (required reading) it is now clear that the new process is NOT based on apodizing filters, but rather on detailed bit-by-bit cancellation tables for the digital filter induced ringing response on both ends of the digital audio datastream.

These tables must alter the digital data in such a way that the errors in the reconstruction filter exactly complement the alterations in the digital datastream itself such that there is NO ringing in the analog output either before OR AFTER a high frequency signal impulse. (In amplifier design parlance, this is in essence, a feed-forward approach, whereas an apodizing filter is, in effect, a negative feedback approach). This is indeed different than conventional LPCM, DXD, or DSD processing. This also explains why simple firmware updates for your existing DAC's may not be sufficient, because the computing horsepower required to do this, in real-time playback, is quite intensive.

Bob also states that a MQA topology for MCH surround processing has been under development, but that it requires two decodes - one before the DSP processing for room correction, etc, and one afterward, just prior to the D/A gateway back to analog. The second decoder presumably updates the complementary correction tables for changes the surround DSP's make in the digital data stream. This also makes sense to me, because if, for instance one chooses to use Trifield, a unique "rendering" file must be created for 3-6 data streams, vs. the two MQA encoded data streams that come into the box from the source.

In any case, It appears a MCH MQA solution is in the plan, however, Stuart and Meridian are not quite ready to talk about it yet. I, for one, will save my nickels for when the 861v9 or G65.1 are announced, but I see no need to spend more than $299 for an Exploerer 2 until then. The ironic thing is, even with an Explorer 2 DAC, my G68 will screw up the decoded signal as soon as it goes into any analog input, because the G68 has no analog pass-thru. The irony is that Stuart may very well end up selling a lot of Meridian owners on someone else's brand analog preamp - make mine a Pass XP-10.

My fear is, when it's all said and done, the investment hurdle and lack of upgrade capability may resign a lot of audiophiles to 2-channel analog listening on their high-end systems (ala MQA-mastered vinyl), and MQA on their computers... not exactly what everyone was expecting at the start of this.

That gets to my original point - Meridian became highly successful by bringing high definition multichannel digital sound into being. If they can't, quickly, work up a transition plan for this market space, (i.e. MCH MQA), then it will either die, or be (unconsciously) adopted by primarily today's MP3 consumer, with little new business for Meridian itself.

Technology innovation and working business models are not intrinsically linked.