Is DEQX a game changer?

Thanks for posting that article, jeffrubin. I stumbled upon another article I thought was germane to this thread given all the talk of measuring speakers and interpreting frequency response graphs in the DEQX calibration software. I got an extra kick out of this since I own the Revel F208s that are featured in this test.

http://www.soundandvision.com/content/speaker-measurements-101#RUfrx2HukdlGAS8i.97

WARNING, I’m about to bring up the controversial subject of MQA. I have been following MQA with great interest these last couple years. I haven’t had the opportunity to hear it myself, but have read as much as possible about the technical aspects as well as subjective sound quality from likes of Stereophile, AudioStream, Digital Audio Review, The Absolute Sound, and others. I’ve been crossing my fingers for the major labels to adopt the process and for content to start streaming in (pun intended). I feel MQA could be the next big thing in hifi.

I also feel that DSP ala DEQX has major potential for improving hifi. But here’s the rub, we might not be able to have both. According to Benchmark, “MQA requires a lossless transmission system from the file source to the final D/A converter. Benign DSP processes such as a digital volume control (used in moderation) immediately defeat the MQA decoding. The same is true for digital crossovers, digital EQ, and room correction. The MQA stream will be corrupted if any of these common processes are encountered. These common forms of digital processing will shut down the MQA decoder and revert the system to a 44.1 or 48 kHz sample rate and an effective bit depth of 13 to 15 bits.” https://benchmarkmedia.com/blogs/application_notes/163302855-is-mqa-doa

I haven’t heard any hifi journalists/reviewers mention this. I’d feel more confident in the truth of this claim if it were echoed by another trusted and knowledgeable source. But it seems to make sense. If true…that sucks. Both MQA and DEQX are trying to get to better sound through, among other things, timing accuracy. It’s too bad both technologies can’t play nice together.

@jeffrubin, I'm glad you reached out to DEQX and shared their general feedback. I was curious to get their take. I'm not surprised at the response at all. Despite my enthusiasm for MQA, I think i'm in the same boat as you. I think the positives of speaker/room correction and crossover of the DEQX would outweigh the benefit of MQA. That's my current leaning, anyway. 

That said, my music library is HEAVILY based on CD-quality digital streaming via Tidal (controlled by Roon which I'm now using and ecstatic about). If Tidal flips the switch on MQA this century and starts streaming most if not all of their library in that format, I hope it sounds as good or better through a non-MQA DAC than the current format. That's what MQA promises, but I've heard doubters. I tend to trust MQA, backed by reviewers at Stereophile, Audiostream, etc. 

For those who have been waiting for Part 3 of the DEQX articles on Digital Audio Review, it’s up now: http://www.digitalaudioreview.net/2016/09/bring-the-bass-back-with-deqx-and-dynaudio/

This part covers subwoofer integration.

I've been following this thread for a long time and even weighed in last year with a bunch of questions. After moving from the west coast to the east coast and briefly owning a PS Audio DirectStream Junior DAC, I've now made arrangements to buy a used DEQX PreMate Plus. The DSJ has been phenomenal, but I feel the DEQX can help me overcome issues with my room and subwoofer integration. In my new room, I want to reduce some of the hotness in the treble, and uneven bass. I can keep the group updated as i go through the process of setting it up but for reasons I won't get into, it won't get here until early December. 

Does the DEQX get very warm to the touch when left on continuously? I’ll be placing it in a 4-sided shelf that’s open to the front and back. There is plenty of clearance above the unit (6-7”), but only a measly 0.35" of clearance on either side (the vents are located on the sides of the PreMate Plus). The user manual calls for at least 2” of clearance on either side. Should I be worried. My current DirectStream Junior has no vents and gets along just fine in this shelf. 

I heard from another DEQX owner that the company does have speaker correction filters already completed for some speakers, like the KEF LS50. Lucky owners of those models can download the correction filters from DEQX instead of having to them at home. I've reached out to the company to ask if they have a speakers (Revel F208), but haven't heard back yet. Does anyone know what speakers they've tested?

   

Thanks, Al. A well-reasoned response. I’ve been thinking the same thing. It pencils out alright, but it’s not ideal. I’ll have to keep a watchful eye on the heat during listening sessions and place it somewhere else if it gets to be too much. 

I believe the DEQX comes with operating software on a CD. Neither of my laptops have a disc drive so I might need to buy one. Does anyone know if that software can be accessed as a download and not read from a physical disc?

Thanks! That's great news. I've been in contact with Alan Langford. I'll ask him.

I bought my DEQX PreMate+ back in December 2017, and finally got it calibrated on Thursday so I’m now utilizing its digital crossover and room correction functions. Here is a rundown of the setup process, and my impressions. After living with the DEQX as just a DAC-pre for over four months, I can say I’m quite pleased with how the DSP has improved the sound (more on that later).

I was too intimidated by the calibration software to attempt it myself so I booked a session with a reputable “DEQXpert” aka dealer, named Larry Owens, based in Colorado. It took about 3.5 hours from start to finish. While it took longer than the 2-3 hours he estimated, I was quite impressed with Larry’s knowledge and adeptness with the software.

I expected that we’d start by taking near field anechoic measurements of the speakers, but my DEQXpert, Larry Owens felt that might not be necessary. We started by placing the mic at the listening position and based on the measurements, he felt that would be sufficient for us to implement a crossover for the sub/mains and correct the in-room response. I’m not sure exactly why we skipped the near field measurements because much has been made about that element to distinguish DEQX from other room correction products that don’t do speaker correction. I can say that if we’d done those measurements, it probably would have taken twice as long.

Before ever seeing any measurements, I expected a few things: (1) that my subwoofer was set a bit louder than the speakers, (2) that I had some nonlinearities in the bass, particularly due to some dips below 80 hertz, (3) that my left channel near the wall was less accurate due to boundary effect, and (4) that the high frequencies were slightly emphasized in-room. Turns out all of that was true except for the fourth point. The highs were fairly well behaved already.

The speakers (mostly left channel) had a dip around 60-70hz and the sub had a dip around 80-90 hz so by setting a digital crossover at 78hz, voila, both dips were avoided! From there, Larry made a bunch of very precise corrections in both the timing and frequency domain that made things look progressively more beautiful as he went along.

With just a couple hours of listening under my belt, I can say the system's frequency response is noticeably flatter. The sound is more precise; less vague. The bass is less room shaking than before simply because it was set too high, but now it’s definitely tighter and more articulate. It makes it easier to follow a bass guitar line and distinguish pitch (less monotone bass). I also feel like the bass in more consistent throughout my room, which I didn’t expect and can’t quite explain.

 

My stereo presentation is also noticeably improved after Larry corrected each speaker to more closely match each other. Before the calibration, I perceived my Revel F208 tweeters as a bit too bright so I used the switch on the speakers to turn them down .5-1dB. Larry pointed to a slight peak at a narrow but critical region in the upper mid treble that he suspected might be the culprit. He used parametric eq to flatten that out and I think that solved it. Much better to address that one narrow problem than turn down everything above 3k with that tweeter knob on the speakers. The highs sound more accurate now. Not too prominent nor too recessed.

I will live with this for a while and report back to Larry if any additional tweaking is needed. He’s been a joy to work with.