AudioVero Acourate v3.1 - room correction with bass pre-filtering and Inter-Channel Phase Alignment (ICPA).

After writing the post on Audiolense recently, I thought it would be good to have another peek after a few years now at AudioVero's Acourate (€416 non-EU countries); the latest version 3.1 released in June 2024.

For years, Acourate has been the room-correction filter toolbox I've used (at least since 2016, updated 2019, plus discussion on partial correction in 2021). Now that it has been half a decade plus a pandemic (!) since the step-by-step 2019 update, let's look at the latest version which has brought with it changes in the user interface as well as the Inter-Channel Phase Alignment (ICPA) feature released in version 2 which I had not discussed previously.

Before getting started, a big thanks to Mitch Barnett of Accurate Sound for his YouTube video a couple years back using Acourate 2 showing the technique around pre-filtering and ICPA. I've taken inspiration from his video, applying it to my home set-up, and converting those steps into a written blog format for the current Acourate version. If what I'm doing here is not clear, make sure to also check out the video since Mitch might have already covered your questions/issues there.

Let's get started!

Seating variations, multi-seat correction & multichannel DRC. The audio "sweet spot".

A look at the rear of my room and the sofa seating - surround speakers, LP rack for a little bit of diffusion room treatment. For best practice, it's important to not sit too close to the back wall. I have 3' between the couch and the LP rack, and the rack is about 17" deep before that back wall. 

Before putting the UMIK-1 microphone away after using Audiolense XO as discussed last time, I thought it would be interesting to explore in greater detail what happens with frequency response and time-domain performance as we sit off the "sweet spot" where the measurements were collected and correction calculated for.

In the image above, I've put a meter stick on my listening couch to identify the seating positions 1 and 2-feet to the right and left of that sweet spot so I can take detailed measurements of what happens to the sound coming from the 5 main speakers at those positions with and without DSP turned on.

Multichannel Digital Room Correction with Audiolense XO. And "What's your budget?".

As you might recall from over the years, I strongly believe that one of the most important things one should try as an audiophile seeking high-fidelity - after having a decent sound room, and getting good equipment - is to consider the use of room correction. It could be as simple as frequency-domain EQ correction for larger bumps and dips (as discussed with the Behringer DEQ2496 hardware back in 2013-2014, device measurements here), or the much more sophisticated frequency and time-alignment of filters created by software like AudioVero's Acourate (and 2019 update) capable of much higher resolutions.

The power that one has to optimize and customize the sound runs well beyond most hardware upgrades other than wholesale speaker replacements and changing sound room! The change one can expect with room correction dialed in is astronomical compared to all the snake oil tweaks, cables, hi-res DAC/streamers, even amplifiers you might want to throw at your system.

These days, I've increasingly been converting multichannel content over to my Roon server, typically 5.1 SACDs and DVD-As but also Bluray rips, ideally lossless TrueHD with 7.1 channels. Unfortunately, Roon is currently unable to decode codecs like EAC3-JOC (lossy multichannel/Atmos) or TrueHD (lossless, based on the MLP codec) so the content typically gets transcoded to multichannel FLAC-compressed PCM which can handle up to 7.1.  

Although Acourate can be used for multichannel filter creation, the manual procedure here is unfortunately quite involved and more than most audiophiles would like to get their hands dirty with! Which is why today's post is going to be about multichannel digital room correction using Juice HiFi's Audiolense XO (€390, currently version 6.21). I see that there is the less expensive Audiolense Surround which I suspect could be enough for many users, and if all you need is 2-channel stereo, there's Audiolense 2.0.

MEASUREMENTS: Oppo BDP-105 RCA, XLR, HDMI, and other stuff for the record (like MQA CDs?!)...

Recently, I was looking at my directory of audio measurement data and realized that I forgot to put up the measurements I had collected on the Oppo BDP-105 Blu-Ray player that I borrowed from a friend in late 2016. I believe the BDP-105 has been discontinued in anticipation of the next generation flagship. The last version of the 105 was the BDP-105D which added DarbeeVision DSP video processing. This would likely not affect the audio side which is what I explore in this article and I'll obviously leave it to the videophiles as to whether this processing is beneficial or not.

As you probably are aware, this device caused quite the stir in the audio and home theater communities back in 2013 when it was first released. For a reasonable price as a universal disk player, it was capable not only of the usual CD/DVD/(3D) Blu-Ray playback but also SACD, DVD-A, and even HDCD decoding. All with flexible digital input choices - USB, TosLink, coaxial, and HDMI. For analogue output, it has single-ended RCA (stereo and multichannel) and balanced XLR analogue (stereo only) connectors. Already in 2013, Oppo had gained a reputation as a good brand with their previous models, but I think this device really put them fully on the map for audiophiles and videophiles alike looking for a reasonably priced (~US$1200 at the time) device that neither sacrificed features nor quality.

For audiophiles, the high-resolution audio output is handled by the pair of ESS Sabre32 Reference ES9018 DAC chips inside. According to the BDP-105 Wiki for those curious: "In the BDP-105's stereo board design, the 4 pairs of DACs in the ESS9018 DAC are allocated as: 1 pair for the RCA outputs, 1 pair for the XLR outputs, and 2 pairs stacked for the headphone amplifier." The other ESS chip is used for the multichannel RCA output.

Years ago, I published some results for this player (along with a DSD followup) and showed that it is indeed a very competent high-resolution device. That was back in 2013 when I was just starting this blog. Over time, I have incorporated a few more measurement and I thought it would be fun to revisit the device. This time, with my newer ADC, have a look at the digital filter in greater detail, explore the difference between the use of RCA and balanced XLR cables, and see if digital input with the USB-B interface differs from HDMI, and the S/PDIF variants... I suspect many of us have heard the BDP-105 over the years, so this might provide a nice opportunity for objective-subjective cross-correlation.