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[(Edit - And yet the owner of stereonet threatened me with legal action if I did not withdraw this comment - why ??)]

This story is about two years old and wasn't apparent to me at the time until later when someone had alerted me to it. This is just another one of the many disappointing situations I have had to deal with since I started this project. In fact I could easily write a book about all of the crap situations and experiences I have had to deal with and the irony is that they have all originated from here within Australia

Check it out !! Slap bang right in the middle of our pre-order period around August 2019 last year on http://www.diyaudio.com , DEQX along with their mates at stereonet all of a sudden decided to offer a 21st anniversary sale !!

What a coincidence or more likely a conspiracy !!



I mean what commercial organization celebrates a 21st anniversary whilst at the same time offering a significant discount on a competing inferior product that they have never offered before ?? Same old story wheeled out once again about an old sampling keyboard that has been flogged to death !! A bit like the old Hills Hoist !! Probably just a rouse to justify offering a discount to try and steal customers away from us at a critical time

20th anniversary I could understand but 21st anniversary ?? What commercial vendors do 21st anniversaries ?? Maybe I have lived a sheltered life but why not a 22nd anniversary during Covid-19 when things are much quieter ? Makes much more sense  but not a peep out of them. Wonder what they will do for a 25th anniversary or maybe they will wait for my next pre-order ? That should be interesting. My guess is that with the same old stagnating DSP hardware it won't belong before the product they are flogging is relegated to the same status as their old keyboard. (PS Apparently DEQX have been working on a new product offering but have not heard any news about it yet.)

And lastly if DEQX was so good then the owner of stereonet would still be using one in his stereo system today. He doesn't and sold it long ago !! (Edit - And yet the owner of stereonet threatened me with legal action if I did not withdraw this comment - why ??) It's one thing trying to steal customers away from a prospective start-up during its critical phase but it's another trying to do kill off a progressively new product whilst keeping a very old outdated and mediocre product alive ! It's called anti-competitive behavior and there are laws designed to protect businesses against this sort of nefarious behaviour !

If you are a local aussie hifi manufacturer my suggestion is to avoid stereonet like the plague and if you read the other threads in this section you will see why ! Why pay $2,000 a year only to have a single forum buried among many others when as soon as you stop paying that thread and all of its posts disappear into the ether. Surely this is not the behaviour of a "hifi community" but  nothing more than a glorified advertising platform designed to make lots of money for its owners whilst using the members as its captive audience who are very limited in what they can post. And if that means destroying a prospective local hifi manufacturer along the way then be it ! Avoid !

Regards
David

https://www.stereonet.com/forums/topic/514388-stereonet-changing-of-the-guard/

I call BS on his claims. No remorse or apologies just blaming everyone else ! He didn't go far enough in changing the guard, because he should have volunteered to remove himself and allow someone else to take over who doesn't have ulterior motives. Changing the names of the mods and admins to "volunteers"? and calling it a "community" is just window dressing and does nothing to change the underlying militant culture with this forum.

I strongly believe that we need a Hifi community that is more receptive to local industry and supportive of local manufacturing jobs rather than overseas jobs facilitated by import junkies that proliferate on his forum. These are people who add no value to anything and seem to have higher priority than local product developers just because they are willing to pay a lot more. If he wants to call it a 'hifi community' then it needs to be treated as a 'hifi community' and not as a cash cow dressed up as a community forum.

Anytime anyone plugs their own products on his forum he pounces on them like a hawk and they get shown the door unless they are willing to pay, except for Elektra of course who appeared to have a lifetime free subscription without being an official sponsor. On the flip-side a well-known Chinese valve amp manufacturer who appears not to be a paying sponsor has already a 222 page thread with over 5500 posts ! Not only that, many forums such as ASR, diyaudio, WBT allow you to plug your own product or company without getting a private message asking you to pay up or have your website removed from your signature ! In my case I was completely shut down and the stereonet forum nobbled so any search for my product on his forum now takes a ridiculous amount of time and still does. It's still the same today so, so much for his "nurturing"?. Like I said it is all crap.

On the drawing board is our next Revision(D) of the main DSP board which now features an upgraded ADC (Analog to Digital Converter) from the existing 24 bit TI part to the Flagship ES9822PRO 32 bit ESSTech ADC. The ES9822PRO ADC features ESS proprietary Hyperstream II ADC Architecture, which delivers unprecedented conversion performance and yields top notch specs of 124 dB DNR and -117 dB THD+Noise. The ES9822PRO has an Ultra-Low Noise Floor Bandwidth of 200kHz. This bandwidth is up to 10 times wider than the competition, enabling higher resolution at higher sampling rates and along with the ESS 8-channel ES9038PRO Sabre DAC and our own onboard FEMTO master clock providing infinitesimal jitter we are certain this should satisfy the most fastidious analog aficionados who are into vinyl or reel-to-reel playback ! 

[Download link to deleted thread below:]

One astute reader contacted us recently and asked why there was nothing on stereonet about our products as he was interested to find out more and get some user feedback but told us that the forum search always produced no results when searching for 'Analog-Precision'? so we had to investigate this for ourselves. For those not familiar with stereonet it is nothing more than a glorified advertising platform masquerading as some kind of 'hifi community' with the members being used as its captive audience but it is anything but a hifi community with its draconian style of censorship and restrictions unless you are willing to pay the $$$ to have some of them removed

Anyway check it out. It seems the reader was onto something here with a search for 'Analog-Precision' yielding absolutely nothing. Maybe I have got the spelling wrong but I checked numerous times and each time it yields 0 results. So the plot thickens



Perhaps it is not returning a result because there is nothing to find ? I told the reader who contacted me that they probably didn't find anything on stereonet because we have been blacklisted and the only thread that was specific to the Preamp has been completely removed by the owner of that forum, however I had the foresight to grab a copy of the thread before it disappeared and have provided a link at the end of this post where you can download it. The reason why this happened is that I believe the owner of that forum and one of its paying sponsors tried to undermine our business by attempting to siphon away prospective customers from us at a critical time of the pre-order for our 2nd generation Preamps. When I complained about it on this forum I received a very abrupt and threating PM from the owner of stereonet requesting that I remove a couple of statements which I refused to do and the rest is history ! Neither statements had anything to do with the underlying issue but more about the so called reputation of the owner of stereonet. 

You will also notice that we have not been added to their list of Australia made product websites even though we probably make one of the most sophisticated and technically advanced consumer audio products in Australia at the moment ! Apparently our website was added only for a very short period of time before it was pulled again ! Check it out analog-precision is missing in action !



Perhaps they don't think we are worthy of any addition because in the owners own words we are just a bunch of 'hacks' struggling to get something to market whilst the owner of stereonet was hatching up plans with one of its paying sponsors to steal away prospective customers from us at a critical time ! And I am glad he agreed that our product works because I don't think he has ever created anything himself or understands how difficult it is !



Having said that, there are still some remnants and old posts that refer to our product or website on stereonet but we had to dig hard just to find one of them as the search engine has been crippled for anything to do with us !

https://www.stereo.net.au/forums/topic/310890-generic-dsp/?tab=comments#comment-4535353



To prove the forum search is not broken let's try some other search terms such as 'minidsp' which I believe is not a sponsor but gets plenty of free plugs every day and all day long. Go figure ! All 22 pages of search results which reference this particular brand !! Not bad for a vendor that doesn't pay a single cent of sponsorship !



For what it is worth I had the foresight to take a copy of the only thread about the Ultimate-Preamplifier Mk-1 before it had been completely removed and have made it available below as a pdf download below including the owner requesting that I apologize to him which he later retracted from that thread before he removed the thread altogether! I won't be apologizing to him for anything as he has a number of apologies to make to others before he seeks redemption for his own misdeeds.  Funnily enough I wasn't banned outright although I can still log on but not post or access the PM's but this was a while ago and I haven't checked since !!

 

Download link to deleted thread below:

screencapture-stereo-net-au-forums-topic-239319-analog-precision-ultimate-preamplifier-2021-02-14-21_49_37.pdf

[Test Methodology:]

Test Methodology:

In this test we are looking at how the DAC is good at resolving very low level signal levels or in other words its micro-dynamic resolving capability. In this case we feed each channel a low level digital signal of -90.31 dBFS which corresponds to a full-scale (0dBFS) signal divided by 32768 or a reduction of signal magnitude by 16 bits which is the lowest level for redbook CD ! This is a 32bit DAC so still has plenty of bits left in the tank to resolve this detail

Conclusion:

Even with a reduction of level equivalent to 16bits in magnitude we see the Ultimate Preamplier has no problem and resolves it cleanly compared to the DEQX Premate which adds a lot of noise and distortion to the signal.

[Introduction:]

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.

[Test Methodology:]

Test Methodology:

The configuration is loaded with a twin tone in the signal generator, with two high frequency tones (19kHz + 20kHz) at amplitudes of -7dBFS each, and separated in frequency by 1kHz. The analyzer measuring the first-order difference frequency at 1kHz using a highly-selective FFT-based filter.



Test Results:

• 2-Channel Direct DAC mode
• 2-Channel Preamplifier Mode using the ASRC
• IMD vs Ampltude
• DEQX PreMate, HF intermodulation spectrum from a Stereophile review

Conclusion:

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

[Test Methodology:]

Test Methodology:

In this test we excite the DAC with a 1KHz impulse train at -3dBFS and observe the impulse response on a scope for each of the seven different reconstruction filters available in the DAC settings menu.

Test Results:

• Fast roll-off, linear phase filter
• Slow roll-off, linear phase filter
• Fast roll-off, minimum phase filter
• Slow roll-off, minimum phase filter
• Apodizing, fast roll-off, linear phase filter
• Hybrid, fast roll-off, minimum phase filter
• Brickwall filter

Conclusion:

[Introduction:]

Introduction:

In this exercise we continue on with the jitter tests using the J-test methodology outlined in our original jitter test thread but this time we want to see how the jitter performance varies as we change the DAC Digital PLL bandwidth. The ES9038PRO DAC has 15 different settings for Digital PLL bandwidth but obviously the tighter the bandwidth the better the jitter performance but this comes at the expense of the DAC being able to lock onto an asynchronous signal with inherent jitter so there is a trade-off between bandwidth and jitter tolerance.

Test Methodology:

There are a variety ways of measuring jitter but the single single RMS or peak jitter metric is not very revealing since it does not reveal the nature of the jitter, so a more detailed analysis such as the J-test method is used to test the susceptibility and tolerance of the device under test. The J-test methodology is described on the ASR forum J-test methodology 1 and J-test methodology 2

Test Results

• DPLL BW Register = 1
• DPLL BW Register = 2
• DPLL BW Register = 3
• DPLL BW Register = 4
• DPLL BW Register = 5 (default)
• DPLL BW Register = 6
• DPLL BW Register = 7
• DPLL BW Register = 8
• DPLL BW Register = 9
• DPLL BW Register = 10
• DPLL BW Register = 11
• DPLL BW Register = 12
• DPLL BW Register = 13
• DPLL BW Register = 14
• DPLL BW Register = 15

Conclusion:

Below the DPLL BW setting of 5 there doesn't seem to be any more improvement in jitter to be had so it seems like this setting is the best compromise between jitter performance and PLL bandwidth.

[Test Methodology:]

Test Methodology:

In this test we excite the DAC with a 1KHz square wave at -3dBFS and observe the step response on a scope for each of the seven different reconstruction filters available in the DAC settings menu.

Test Results:

• Fast roll-off, linear phase filter
• Slow roll-off, linear phase filter
• Fast roll-off, minimum phase filter
• Slow roll-off, minimum phase filter
• Apodizing, fast roll-off, linear phase filter
• Hybrid, fast roll-off, minimum phase filter
• Brickwall filter

Conclusion:

[These preamps operate in perfect sync with each other and the master preamp controls the volume, balance and muting on all of the other slave preamps in perfect unison.]

We had a recent enquiry by someone who wanted us to build a preamp with 16 outputs ! But what if someone asked us to build a 24 or 32 or even a 48 channel or more hi-end stereo pre-amp and our preamp only had 8 outputs? Fear not with the external Link-Port on both the UP2 and UPP you can chain as many preamps together as you need to get as many outputs as you need with no loss of information or performance ! Why would you need such high channel count ? One application comes to mind and that is a phased array loudspeaker or wave shaped loudspeaker with many independent driver channels such as the B&O kii audio etc or even a multiple active speaker that are all controlled by the same pre-amp.

By itself the Ultimate Preamp 2/+ has 8 outputs plus an optional digital output to drive an external stereo DAC bringing the total output count to 10 channels which is still far short of 48 channels. However, the main DSP board used in the preamp has provision for connecting multiple DSP boards as a master and many slave arrangement in the one chassis using the on-board Link-Port connector.

However, from a practical point of view this would require a redesign of the enclosure and power supply to handle multiple boards and output connectors which is just not practical at this point in time. We just needed to extend this facility outside the chassis so that we could link multiple preamps in 8-output clusters and they all needed to sync perfectly together when changing things like the volume, balance, mute etc because you don’t want to have to adjust each preamp’s volume control every time you need to adjust the volume.

Because this was a planned feature for the UP2 and UPP we needed to make sure it worked perfectly before we started shipping the preamps so whilst we still have all of the preamps in our lab undergoing testing before we ship them what better time to test out this feature which is why we have spent the last week updating the firmware and hardware to make sure it all works as advertised. As an example we took 6 preamps and chained them all together in a one-master five-slave system to give a total channel count of 48 channels !. We also loaded the simple Audioweaver pass through example which feeds a stereo signal directly to all 8 channels but this could be any design of your choosing. It also helps us test the HDMI I2S input and the Link-Port HDMI output ports on the preamp at the same time 😉

The bottom preamp is assigned the master preamp and the top five preamps are assigned slave preamps connected in daisy chain fashion using HDMI cables.

These preamps operate in perfect sync with each other and the master preamp controls the volume, balance and muting on all of the other slave preamps in perfect unison.



48 channel VU meter operating in real time !



Muting works across all preamps as well.



A 48 channel Preamp playing vinyl

[Test Methodology:]

Test Methodology:

In these tests we are using a wide bandwidth digital scope to view the 49.152MHz master clock waveform at various points in the clock network. It is impossible to make proper measurements of a clock source unless you use a scope with a suitable bandwidth that can at least capture the 21st harmonic of the fundamental frequency of the clock frequency which means a scope with at least a 1GHz bandwidth. Not only that you need to use a probe with an equivalent or greater bandwidth to the scope and preferably an active probe to minimize loading.

To avoid loading down the device under test we use an active probe (Tek P6204) with at least 1GHz bandwidth along with the shortest ground connection to minimize loop inductance in the probe which would manifest itself as ringing in the waveform. We used a Tektronix TDS784A DSO scope with a 1GHz bandwidth and real time sampling rate of 4Gs/s as well as a 10Gs/s equivalent time sampling rate for our measurements. For the expanded scale measurement the scope was set to an equivalent sampling rate of 100 Gs/s. What we are looking for is minimum ringing and overshoot without any kinks in the clock transition interval.

Test Results:

• Frequency Measurement
• Raw Output from the master clock oscillator
• Buffered Output from the clock buffer chip feeding the DAC
• Buffered Output from the clock buffer chip feeding the ADC
• Buffered Output from the clock buffer chip feeding the timing logic !

Conclusion:

As one can see from the scope shots below that in all cases the clock wave-forms are clean and stable and show minimum overshoot which means that the clock outputs are properly matched to the board traces in order to minimize transmission line effects and reflections.



Tektronix P6204 Low Capacitance Active Probe with 1GHz bandwidth



Active Probe applied to clock circuit using the shortest possible ground connection for minimum induced ringing and overshoot

Since we have an interest in using some of the products from Purifi Audio in a new project this article makes for interesting reading

https://www.hifishark.com/article/visiting-purifi-audio

The Latest test results and measurements from our Lab show the Ultimate-Preamplifer 2/+ meets or exceeds its design objectives by a huge margin ! Click here to view more.

[Applies to:]

Applies to: EUTs with analogue or digital inputs and analogue or digital outputs.

Aim: To measure the THD+N of the EUT against frequency.

Method
A -1dBFS sinusoidal stimulus is applied to the EUT, successively at each octave frequency between
20Hz and half the upper band-edge frequency. The output of the EUT is passed through a standard
notch filter at the frequency of the stimulus, and also through a low-pass filter at the upper band-edge
frequency (or at 20kHz, whichever is the lower). The RMS amplitude of the residual is measured for
each stimulus frequency.

The results are presented graphically, with THD+N (in % relative to the amplitude of the stimulus)
being plotted for each channel against stimulus frequency.

The test is then repeated with a stimulus amplitude of â€"20dBFS, the results being overlaid on the
original graph.

[Applies to:]

Applies to: EUTs with analogue outputs.

Aim: To measure the total of HF imaging components beyond the audio band which are output from
the EUT's D/A converter, as a result of applied audio-band signals.

Method
The analogue output of the EUT is measured with a â€"20dBFS sinusoidal stimulus applied, swept from 10Hz to the upper band-edge frequency or 10kHz (whichever is the lower). Components within the audio band are excluded by using the standard high-pass filter. The total RMS amplitude of all the components above the upper band-edge frequency of the EUT is measured for both channels at each frequency, and plotted graphically. The greatest result for each channel,expressed in dBFS, is also presented at the end of the test.

References
http://resources.prismsound.com/tm/dS3_Applications_Manual_A4nc.pdf

[Applies to:]

Applies to: EUTs with analogue or digital inputs and analogue or digital outputs.

Aim: To measure the inter-channel cross-talk between the channels of the EUT at a range of
frequencies.

Method
The input of the EUT's driven channel is fed with a sinusoidal stimulus at â€"20dBFS which is swept in
octave steps from 10Hz to the upper band-edge frequency. The input to the un-driven channel (if
digital) is fed with a digital-zero signal or (if analogue) is terminated with 50R (or 25R if unbalanced).
At each frequency, the ratio of the RMS amplitude of the output of the un-driven channel (measured
through a 1/3 octave band-pass filter at the stimulus frequency) to the RMS amplitude of the output of
the driven channel is measured, and displayed graphically in dB against frequency. The un-driven
and driven channels are reversed and the test is repeated. The two channels are overlaid on the
same axes so that worst-case cross-talk can be easily seen.

Conclusion

The UP exhibits a maximum cross-talk of 110dB all of the way up to 10kHz and at least 107dB at 20KHz. Below 1kHz the cross-talk is at least 125 dB  !

Compared with DEQX from Stereophile .

"Channel separation was excellent, at >115dB in both directions below 1kHz, and still 95dB at 20kHz."

we can see that the Ultimate-Preamplifier is indeed superior in terms of channel separation and cross-talk !

References
http://resources.prismsound.com/tm/dS3_Applications_Manual_A4nc.pdf

[Applies to:]

Applies to: EUTs with analogue or digital inputs and analogue or digital outputs.

Aim: To measure power-line (mains) related products in the output noise of the EUT.

Method
If the EUT has a digital input, it is fed with a digital-zero signal; if the EUT has an analogue input it is
terminated with 50R (or 25R if unbalanced). The operator nominates either 50Hz or 60Hz power-line
frequency.
The RMS summation of the signal components in the EUT output at the power-line (mains) frequency
and its second through fifth harmonic is reported for both channels, in dBFS (in the case of an
analogue measurement, this is equivalent to dB below the specified D/A line-up).
Note: only components at the power-line (mains) frequency and its second through
fifth harmonics are included in this test. Artifacts from a high-frequency switching
power supply are classified as spurious components.

References
http://resources.prismsound.com/tm/dS3_Applications_Manual_A4nc.pdf

[Applies to:]

Applies to: EUTs with analogue or digital inputs and analogue or digital outputs.

Aim: To measure the output noise of the EUT in the presence of signal.

Method
The EUT is fed with a 997Hz sinusoidal stimulus at an amplitude 60dB below its maximum signal
amplitude (â€"60dBFS).
The output of the EUT is passed through a standard notch filter at the frequency of the stimulus, and
also through the standard weighting filter. The RMS amplitude of the residual is measured for both
channels, in dBFS (in the case of an analogue measurement, this is equivalent to dB below the
specified D/A line-up), and designated as 'dBFS CCIR-RMS'.
See also: Level Search Routines for fault finding with this test.

Conclusion

The DNR for 8 channel differential current mode from the spec sheet for the ES9038PRO is 132 dB-A directly from the DAC output so this measurement is consistent with that measurement if we take into account the additional Noise Figure of both the IV converter and external buffer amplifiers.

References
http://resources.prismsound.com/tm/dS3_Applications_Manual_A4nc.pdf

[Applies to:]

Applies to: EUTs with analogue or digital inputs and analogue or digital outputs.

Aim: To measure the output noise spectrum of the EUT with no signal present.

Method
If the EUT has a digital input, it is fed with a digital-zero signal; if the EUT has an analogue input it is
terminated with 50R (or 25R if unbalanced).
The RMS amplitude of the output noise of the EUT is measured via the standard weighting filter in a
range of 1/3 octave bands between 20Hz and the upper band-edge frequency. The result is graphed
for each channel in dBFS (in the case of an analogue measurement, this is equivalent to dB below
the specified D/A line-up).

References
http://resources.prismsound.com/tm/dS3_Applications_Manual_A4nc.pdf