Ultimate Preamp vs DEQX

[Tranquility Bass]

Introduction:

Whilst we don't actually have a DEQX in front of us to test and compare with, we can still leverage the test results from a recent Stereophile review of the DEQX Pre-mate  which apparently is the same hardware used in all of their models with some changes to the I/O and software capability otherwise it is the the same old hardware except for the cheaper models which apparently use a switch mode power supply instead of the linear power supply used in the more expensive models. Of course the UP uses a linear power supply in all of its models

For a detailed comparison between DEQX and the Ultimate-Preamplifier please click here to refer to our comparison table



Test Results:

• Spectrum of 50Hz sinewave, DC-1kHz, at 0dBFS into 600 ohms
• 16 bit Jitter Test using J-test
• DAC (19kHz + 20kHz) CCIF IMD test
• Waveform and Spectrum of undithered 1kHz sinewave at â€"90.31dBFS

Conclusion:

We can see a pattern emerge here and that in all tests shown below the Ultimate Preamplifier displays superior performance over the DEQX in all cases. Not just a small improvement but a major improvement !

DEQX claim the following from their own website but the measurements from Stereophile review don't really support these claims !

Audiophile-grade engineering

Every aspect of a DEQX is carefully engineered for optimum audiophile performance. For example: countless design, development, and auditioning iterations were put into the latest A/D convertor circuit and the DAC's I/V (current to voltage) convertor circuits. Over a decade of constant refinement and attention to detail has paid off in superlative performance.

Now add in superb digital coding and algorithms: a −140 dB digital processing noise floor and a precision digital volume control. The end result? A truly transparent component with zero digital artifacts. An "analog" sound for all combinations of input to output: analog to analog, digital to digital, and any combination of the two.

DEQX also claim in one of their reviews of "'first do no harm' transparency" but the measurements from Stereophile compared to our own measurements of the Ultimate Preamp show anything but transparency. Add to this an antiquated DSP platform with very limited FIR capability shows that this product is trying to be all things to everyone but succeeding at none of them.

[Tranquility Bass]

Fig.11 DEQX PreMate, spectrum of 50Hz sinewave, DC-1kHz, at 0dBFS into 600 ohms (left channel blue, right red; linear frequency scale).



Shown below is the output from the UP which shows at least an order of magnitude less noise and distortion compared to the DEQX whilst approaching the bottom limit of what the analyzer is capable of measuring !

[Tranquility Bass]

Shown below is the J-test Jitter spectrum of the DEQX Pre-mate as reviewed by Stereophile. Noise floor modulation, spurious artifacts and poor jitter performance shows some issues with this design.



By comparison the resulting spectrum from the Ultimate-Preamplifier below is much cleaner even for 16 bit Red-book standard and does not suffer from noise floor degradation like the DEQX does above. We can see that the DEQX above needs a lot of work to match the outstanding performance of the Ultimate Preamplifier even for Red-Book 16 bit playback



For the 24 bit J-test Jitter Spectrum the news is even better for the UP which is bad news for DEQX with vanishing low levels of jitter artifacts from the UP !

[Tranquility Bass]

Fig.12 DEQX PreMate, HF intermodulation spectrum, DC-30kHz, 19+20kHz at 0dBFS into 100k ohms (left channel blue, right red; linear frequency scale).

Note how the noise floor is lifted up and modulated by the two tones whereas this is totally absent in the UP spectrum ! Again the UP wins hands down when it comes to transparency !



The following test results show that the IMD distortion of the Ultimate Preamplifier is exceedingly low and betters the performance of the DEQX Pre-mate by a long margin !

[Tranquility Bass]

Fig.10 DEQX PreMate, waveform of undithered 1kHz sinewave at 90.31dBFS, 24-bit data (left channel blue, right red).
 


Fig.8 DEQX PreMate, filter operating for Bryston Model T, spectrum with noise and spuriae of dithered 1kHz tone at 90dBFS with: 16-bit data (left channel cyan, right magenta), 24-bit data (left blue, right red) (20dB/vertical div.).



Below is the real time capture of the Left and Right Channels of the Ultimate Preamplifier at -90.31dBFS @ 1kHz 24 bit WL. Compared with DEQX above the output of the UP is significantly cleaner !



Below is the FFT Spectrum of the Ultimate Preamplifier output. Compared with the DEQX above the noise floor is much lower on the UP !

[MichaelH]

Kyron have updated their Gay-ear. With no new offerings from DEQX they must still be using that old klunker from above. I don't know how they can claim what they do about sound quality when the DEQX performs as bad as it does. That sine wave is truly s**t. I don't see how Kyron can charge $250k+ when the electronics they are selling with the loudspeaker is as terrible as what the measurements above show.

"There's a sucker born every minute."�
-- P. T. Barnum

[Tranquility Bass]

Kyron have updated their Gay-ear. With no new offerings from DEQX they must still be using that old klunker from above. I don't know how they can claim what they do about sound quality when the DEQX performs as bad as it does. That sine wave is truly s**t. I don't see how Kyron can charge $250k+ when the electronics they are selling with the loudspeaker is as terrible as what the measurements above show.

“There's a sucker born every minute.�
-- P. T. Barnum

Correct me if I am wrong but I believe their latest incarceration is a rehash of the same electronics they used before with some very minor changes. I believe they are still using the old legacy 96kHZ DEQX design with the old outdated Analog-Devices ADSP21065L 66MHz SHARC DSP, same DAC's and ADC's as before so therefore expect to measure the same as shown above from the Stereophile review. From what I can see most of the changes are only cosmetic ! Be-careful with FIR filtering and high-slope linear-phase crossover designs as the off-axis response can suffer if the on-axis response is highly optimized and there are differences in directivity or timing between drivers in the off-axis in which case the ripple in the impulse response of the high and low filters will not properly cancel out and this can produce an objectionable pre and post ringing in the off-axis impulse response even though the on axis response is perfectly ok with no ringing which kind of negates the claim of no "cabinet resonances" !! Sometimes the medicine is worse than than the disease

cheers
David

[MichaelH]

Even Amir said its not much better than MiniDSP. Now thats an embarrassment considering the price difference.

[MichaelH]

A comment from a HiFi show visitor. Marc made such a song and dance about the Australian Launch of the new "Gen 4" and what happens?

The screen works and thats it. I wonder how much DEQX paid for that 3 day escapade to demo the screen. This would have to be the one of the worst disaster launches in Aus HiFi history. Why did they even bother showing up? I can see now why Kyron are also in the s**t from this inept bunch of clowns who still rest on their laurels from an organ from the 70's. That's all they seem to be able to do is go back 50 years.

Paul Best, Australian Financial Review, May 16, 2022

This audio pioneer is set to transform the way you hear music

Kim Ryrie, the man who revolutionised the music-recording industry in 1979, has been fine-tuning a device that makes high-quality sound way more affordable.

DEQX have transformed the way you listen to music by demonstrating a 5 inch screen in a box with a knob. AFR hailed this as the breakthrough the audio world has waited for since, well basically 1920.

“I flicked the switch,� Ryrie says, indicating the silver box on the table. On it is written: DEQX speaker/room calibration processor. When in fact its a Raspberry Pi in a box with a knob.

That whole AFR pump up was just a load of s**t.

[Tranquility Bass]

That was a wasted opportunity to show case a new product producing good sound through some already half reasonable speakers, that's if it was working of course which it appears not to be. When I first saw those photos I thought straight away why have they got that old rig running for ? I mean it was a cheesy demo that could have easily been setup using a minidsp running Dirac. Seriously no one is going to pay 5-7k to fix up a $150 speaker which no doubt cannot possibly fix up all of the non-linearities or get it to reproduce reference standard bass down to 20Hz at a reasonable SPL and distortion. it just won't happen ! You can't make a silk purse out of a sows ear !

It's no mean feat to pull a new product like this off. First you have to map out the hardware design and using all new chips including a new micro/DSP means there is something you are going to leave off or make wiring mistakes on the schematic. Very easy to do which means reworking the PCB or even worse redoing another PCB or PCB's until you have got the hardware right. Then there is laying out the PCB with high pin count BGA devices, most likely having to use at least a 6-layer or more PCB and if you are mixing analog with digital on the same board then you better know what you are doing because it is easy to screw up. If you are using an ARM core and interfacing to DDR memory then you'd hope the PCB designer has experience with that because that is one thing that is easy to screw up with impedance and trace length matching so good luck with that !

It is possible they are using off the shelf hardware such as raspberry pi and just interfacing it to all of the peripheral audio chips, LCD etc in which case that would be a lot of work saved but you still have to write all of the firmware which is another huge undertaking. This may explain what they were able to demonstrate with no audio processing.

Then there is all of the software written for the PC application running under Windows which is a huge undertaking by itself I Plus there is the mechanical design which is another person on the job who knows what they are doing !

This is at least a five year job just to get to a working prototype if you had to start from scratch and probably no less than a five man team. Fortunately I was able to do the UP all by myself over a few years with only three board revisions which all worked btw with little or no board mods 😉

[MichaelH]

Big missed opportunity. Another Australian company potentially on the way out.

[Tranquility Bass]

Amazing what the google search engine  picks up these days

[MichaelH]

I'm waiting for DEQX measurements, I know I will die before they produce them and anyone that reviews it (read Stereonet here) wont do any measurements because they cant.

[Tranquility Bass]

To quote:-

"20,000 taps total....2000 taps to the tweeter, 4000 taps to the midrange and 4000 taps to the bass"

Really and all at 96kHz sample rate from a pair of first gen SHARC DSP's ?? Somehow I don't think so unless they knew some undocumented SHARC instructions that nobody else knew at the time or they were able to overclock the crapper out of it which gave them 15 times the DSP capability but I doubt it very much LOL

Let's do the math. Assuming they were using a first-gen Analog Devices SHARC aka ADSP-21065L clocked at 66MHz which offers 66 MMacs (million multiply-accumulates or taps per second). This is the same device part used in the popular Behringer DSP crossover but DEQX used two of them - one for each channel. According to the datasheet for this DSP the best case timing for each FIR tap is 15nS which corresponds to a 66MHz clock or 66MMacs performance.



To calculate the number of taps per sample you divide 66 million by the sample rate of 96000 which gives 687 taps per sample for each channel at 96kHz !! And the frequency resolution of these filters would be 139Hz best case ! That's only in stereo though ! Over six channels the figure drops to 229 taps or a frequency resolution of 3x the stereo case or 417Hz !! Seriously !!

To put that into perspective the 4th gen SHARC part used in our preamp and a lot of minidsp products is capable of 800 MMacs + another 800 MMacs from the on-chip FIR accelerators with a grand total of a theoretical maximum of 1.6 G-MAcs or 16,666 taps per sample @96k which equates to a 11.52Hz resolution on both channels @96 kHz !! What on earth were DEQX offering with such a small amount of DSP capability and only until 2021 did they decide to pull this product ? With only 139Hz resolution you won't be doing too much correction below 1kHz ! Am I missing something here or is it just lots of marketing blurb covering up a mediocre product that not too many bothered to scrutinize? What kludges were being done with such a poor "group delay correction" resolution on offer ? It certainly was not 10k taps per channel like it was stated. If 10k taps per channel is now considered inadequate how on earth was a measily 687 taps per channel in the previous DEQX offerings ever going to cut the mustard ?

What on earth have they been selling to all of the punters for all of these years ? Did anyone ever bother to do the back-of-the-napkin calculations ? Was this the real reason they pulled the product around 2020 when I originally published the tap count on our website and then they realized it wasn't too long before someone put two and two together to expose the mediocrity of it all ??

Apart from exaggerating the performance of their previous offerings by a factor of 15x the representative from deqx being interviewed had trouble explaining the definition of a digital 'tap' as it applied to the basic building block of an FIR filter !! This should ring the alarm bells for anyone seeking technical advice from them. Also, the BS about the SHARC parts not offering better-performing devices compared to ARM cores is total balony as I proved in a previous post. Even the 4th gen SHARC part used in our preamps has the same capability of their current multi-core ARM device at the same 48KHz sampling rate !! The truth is they had ample opportunity to upgrade their hardware to better SHARC parts, but instead chose to sell the same bit of old rope as long as they could get away with it. Of course, using better SHARC DSP's now they would then have had to explain the mediocrity of what they have been selling to the punters for decades. Can't have that can we. Instead it was much easier from a marketing point of view to use a completely disconnected CPU/DSP such as an ARM device and then beat-up on the poor old first gen SHARC parts in classic strawman style. This makes perfect sense from a marketing point of view but fails dismally from a technical standpoint

What's even more bizarre is that the main proponent (or should I say the shill from stereonet) of DEQX's latest offerings, who is obsessed with tap count has never once mentioned this performance shortfall instead preferring to exaggerate it as well whilst bagging the competition no matter who or what it is ! Now he says the tap count on their new offerings has jumped eightfold from when he started the thread on ASR but then he also said the tap capability of their previous offering was 4096 taps per channel which is still 6x its maximum theoretical performance. Who knows but the maths certainly doesn't lie

This reason alone is why I do not consider the MiniDSP to be a "serious" solution, it simply does not have the computing power to deliver adequate correction. The older version of DEQX used the same SHARC processor as MiniDSP, but this new DEQX uses an ARM processor which is 64 bit instead of 32, and allows for 4096 taps per channel, or 32,768 taps in total. At 48kHz, this is a resolution of 11Hz, which is a substantial improvement.

Regardless, all versions of the DEQX use Linear Phase FIR filters, rather than mixed phase as per MiniDSP. To get equal performance you need a lot of taps. Older versions did not have enough taps. The new Premate 8 uses an ARM chip, which has 32768 taps per channel, for 8 channels. IMO this is still not enough, but I would consider it adequate. I would prefer 65536 taps per channel or more. But 32768 taps per channel is a substantial upgrade over older versions of DEQX.

So it's a bit of a cheap shot to compare the minidsp offering to the previous DEQX offering just because they use the same vendors DSP but fails to mention that mindsp is using a 4th gen SHARC DSP whereas the previous DEQX models use first gen SHARC DSP's ! In fact, 3 months after starting the thread on espousing the virtues of the new DEQX unit he started a thread on the "Limits of minidsp" and highlighted the fact that 1024 taps per channel was not enough! How about 229 taps per channel for the previous DEQX models ?

What's even more bizarre is the claim that the alleged 32k taps per channel for the new DEQX is not enough and the post's author would prefer 65k taps !! So how does he reconcile only 229 taps per channel for the previous DEQX offering ?? That's a huge disparity to account for. In fact, it's 143 times the last offering product from DEQX which begs the question as to how did the previous offering from DEQX ever work as claimed if they have had to completely redesign it with a substantial performance increase ? Hmmmm !

[Tranquility Bass]

Recently a customer asked me about linearizing the phase of their non-minimum phase crossover they had implemented on the Ultimate-Preamp. Originally specified with two FIR filters comprising of 4096 taps per channel at 192 kHz. Why not increase the filter resolution to 32k taps per channel @192kHz which is equivalent to 128k taps per channel at 48kHz and there is plenty of room left in the tank !! Eat this DEQX shills - why would you bother using a phone chip ??

More info can be found here:- https://analog-precision.com/forum/wiki-and-qa/extending-the-dsp-capability-of-the-ultimate-preamplifier-plus/