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#1
News Updates / A PERSONAL PERSPECTIVE ON THE ...
Last post by Tranquility Bass - November 13, 2024, 01:29:13 PMA great read for anyone interested or skeptical of class-D amplifiers 
LIFE ON THE EDGE – A PERSONAL PERSPECTIVE ON THE PAST, PRESENT, AND FUTURE OF CLASS D AUDIO AMPLIFIERS
BRUNO PUTZEYS OCTOBER 22, 2024 30TH ANNIVERSARY THE NOW
LIFE ON THE EDGE – A PERSONAL PERSPECTIVE ON THE PAST, PRESENT, AND FUTURE OF CLASS D AUDIO AMPLIFIERS
BRUNO PUTZEYS OCTOBER 22, 2024 30TH ANNIVERSARY THE NOW
#2
Performance and Measurements / Re: Ultimate Preamp vs DEQX
Last post by Tranquility Bass - November 07, 2024, 09:57:20 AMin a recent interview it was claimed the previous gen DEQX was capable of 20k taps from both channels or 10k taps per channel at 96KHz !! To quote
Really and all at 96kHz sample rate from a pair first gen SHARC DSP's ?? Somehow I don't think so
Assuming they were using a first gen Analog Devices SHARC aka ADSP-21065L clocked at 66MHz which offered 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 a 11.52Hz resolution on both channels !! What on earth were DEQX offering with such a small amount of DSP capability ? With only 139Hz resolution you only have 143 points of correction over a 20kHz bandwidth !! 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 is certainly not 10k taps per channel like it was stated. Absolute poppycock !! Maybe someone can chime in and prove me wrong but something is not adding up here !!
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 like I have done ? Was this the real reason they pulled the product when I originally published the tap count on my 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 30x 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 they 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 they would then have to explain the mediocrity of what they have been selling to the punters for decades. Can't have that can we
Quote"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 first gen SHARC DSP's ?? Somehow I don't think so
Assuming they were using a first gen Analog Devices SHARC aka ADSP-21065L clocked at 66MHz which offered 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 a 11.52Hz resolution on both channels !! What on earth were DEQX offering with such a small amount of DSP capability ? With only 139Hz resolution you only have 143 points of correction over a 20kHz bandwidth !! 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 is certainly not 10k taps per channel like it was stated. Absolute poppycock !! Maybe someone can chime in and prove me wrong but something is not adding up here !!
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 like I have done ? Was this the real reason they pulled the product when I originally published the tap count on my 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 30x 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 they 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 they would then have to explain the mediocrity of what they have been selling to the punters for decades. Can't have that can we
#3
Ultimate-Preamplifier by Analog-Precision / Re: Please Read !
Last post by Tranquility Bass - October 27, 2024, 07:00:51 PMBut wait there is more from Analog-Devices !!
https://www.analog.com/en/products/adsp-21837.html
Check it out. With 24 GFLOPs and 8 GMACS floating point performance That's equivalent to 41,666 taps at 192KHz or 83,333 taps at 96KHz or 166,666 taps at 48KHz. What's not to like ? That's why you use a dedicated DSP and not a phone chip when it comes to doing hi-end audio
https://www.analog.com/en/products/adsp-21837.html
Check it out. With 24 GFLOPs and 8 GMACS floating point performance
That's equivalent to 41,666 taps at 192KHz or 83,333 taps at 96KHz or 166,666 taps at 48KHz. What's not to like ? That's why you use a dedicated DSP and not a phone chip when it comes to doing hi-end audio #4
Ultimate-Preamplifier by Analog-Precision / Re: Please Read !
Last post by Tranquility Bass - October 27, 2024, 05:45:17 PMHey Xawo have you heard the latest news ? Someone recently asked a question on DEQX's facebook page for the tap count of their latest DEQX processor for which you could hear the crickets sounding until that post was deleted as have many others on that thread. In fact out of 15 comments only 6 are displayed. Hmmm According to sources from ASR it is 32k taps @48kHz or 4k taps per channel for the 8-channel version. And bear in mind this figure of 32k taps is at 48K sampling rate. Hardly call that SOTA these days. More like entry level. At 192k (which is what our own UP2 and UPP defaults to), the tap count is reduced to only one quarter of the 48K rate or 8k in total or 1k taps per channel !!
Now a single core 5th gen SHARC ADSP-21569 DSP is capable of a best-case scenario of 4G-MACs (multiply accumulates or taps per second) from both the core and on-chip accelerator hardware. Divide this by 48KHz and you get 83333 taps per sample @48KHz !! Sorry DEQX your 2GHz 6-core phone chip is already outclassed by a single core 5th gen SHARC DSP that only clocks at 1GHz !! Why is it so ? The ARM core relies on cache architecture to achieve its performance. Still, for long length FIR filters this is not necessarily optimum because unless the FIR fits within the data cache the cache can easily be flushed by other code and data at any time. Then you are up a creek without a paddle. Whereas the SHARC DSP has dedicated single cycle on-chip pipeline RAM which can be used for dedicated FIR filters without other code interfering with and invalidating it !! You could of course segment the FIR to run on multiple cores but for a 6-core ARM device allegedly used on the latest DEQX (for which no part numbers have been offered) you would expect a much higher aggregate tap count than a single-core SHARC DSP that runs at only half the clock rate but it aint so
Of course, you could use FFTs to do the FIRs, and this is where the SHARC has an advantage because it has on-chip hardware for FFTs. Unfortunately, the ARM doesn't, so it's probably ham-strung in the same way as it is for FIRs.
The other thing is these phone chips were never really expected to process any audio above 48KHz and why should they ? It's a phone stupid not a dedicated music server or multi-way crossover ! It simply doesn't need to process anything above 48KHz such as 96K or 192K etc. In addition, like a phone, they are running Linux or some operating system on the same processor used for DSP so you now have a layer of bloatware competing with the same resources needed for high-performance DSP. (insert face palm moji) !!
The moral of the story is always use the right tool for the job which is why AVR manufacturers use dedicated DSP's such as the SHARC instead of phone chips and that is why we use a SHARC as well.
According to sources from ASR it is 32k taps @48kHz or 4k taps per channel for the 8-channel version. And bear in mind this figure of 32k taps is at 48K sampling rate. Hardly call that SOTA these days. More like entry level. At 192k (which is what our own UP2 and UPP defaults to), the tap count is reduced to only one quarter of the 48K rate or 8k in total or 1k taps per channel !!Now a single core 5th gen SHARC ADSP-21569 DSP is capable of a best-case scenario of 4G-MACs (multiply accumulates or taps per second) from both the core and on-chip accelerator hardware. Divide this by 48KHz and you get 83333 taps per sample @48KHz !! Sorry DEQX your 2GHz 6-core phone chip is already outclassed by a single core 5th gen SHARC DSP that only clocks at 1GHz !! Why is it so ? The ARM core relies on cache architecture to achieve its performance. Still, for long length FIR filters this is not necessarily optimum because unless the FIR fits within the data cache the cache can easily be flushed by other code and data at any time. Then you are up a creek without a paddle. Whereas the SHARC DSP has dedicated single cycle on-chip pipeline RAM which can be used for dedicated FIR filters without other code interfering with and invalidating it !! You could of course segment the FIR to run on multiple cores but for a 6-core ARM device allegedly used on the latest DEQX (for which no part numbers have been offered) you would expect a much higher aggregate tap count than a single-core SHARC DSP that runs at only half the clock rate but it aint so
Of course, you could use FFTs to do the FIRs, and this is where the SHARC has an advantage because it has on-chip hardware for FFTs. Unfortunately, the ARM doesn't, so it's probably ham-strung in the same way as it is for FIRs.
The other thing is these phone chips were never really expected to process any audio above 48KHz and why should they ? It's a phone stupid not a dedicated music server or multi-way crossover ! It simply doesn't need to process anything above 48KHz such as 96K or 192K etc. In addition, like a phone, they are running Linux or some operating system on the same processor used for DSP so you now have a layer of bloatware competing with the same resources needed for high-performance DSP. (insert face palm moji) !!
The moral of the story is always use the right tool for the job which is why AVR manufacturers use dedicated DSP's such as the SHARC instead of phone chips and that is why we use a SHARC as well.
#5
News Updates / Local audio vendors and suppli...
Last post by Tranquility Bass - September 26, 2024, 09:36:55 AMLately, I have been seeing more and more Facebook ads from local vendors. Obviously, the Facebook algorithm determines that I am local and what interests I have so it knows which ads to display on my feed. Some of these local audio vendors used to be sponsors on that you-know-what over-saturated, highly restricted, over-censored, intentionally suppressed images, highly manipulated, expensive and ineffectual forum until they could see the writing on the wall ! Now they are popping up on my Facebook feeds and undoubtedly others interested in this area. Could this be a trend for other local vendors and manufacturers? Hmmm, only time will tell, but the important thing here is that no one person with ulterior motives for a grab for money is manipulating their outcomes by playing one vendor off against another. All done with clever algorithms
The list just keeps getting bigger and bigger by the week !!
The list just keeps getting bigger and bigger by the week !!
#6
Performance and Measurements / Re: A question for DEQX owners...
Last post by Tranquility Bass - August 21, 2024, 05:36:06 PMAnd here in lies the rub !
https://www.audiosciencereview.com/forum/index.php?threads/deqx-premate-8-digital-active-crossover-dsp.48884/post-2060183
Yes what is the optimum measurement distance for any speaker ? Surely it can't be the same for every speaker and if so what exactly are you measuring at the recommended 1 meter ? And to add, this simply will not work for speakers like the Duntech's or Dunlavy's and probably a lot of other speakers too. They have been optimized or designed with a focal point of about 3.3 meters or 11 feet. To state that people should place a microphone at an arbitrary distance of 1 meter is a flawed assumption and does not consider the manufacturer's design objectives. Doing this would totally screw up the response using this device! This is why Dunlavy invested in two anechoic chambers! And who says 1-meter is the optimum position as though it is written in stone and why ? DEQX have been advocating this procedure for years along with using linear-phase filters with all of their pitfalls. It is little wonder nobody in the hi-end audio industry uses a DEQX to design a speaker. It's nothing more than a pipe dream !
https://www.audiosciencereview.com/forum/index.php?threads/deqx-premate-8-digital-active-crossover-dsp.48884/post-2060183
Yes what is the optimum measurement distance for any speaker ? Surely it can't be the same for every speaker and if so what exactly are you measuring at the recommended 1 meter ? And to add, this simply will not work for speakers like the Duntech's or Dunlavy's and probably a lot of other speakers too. They have been optimized or designed with a focal point of about 3.3 meters or 11 feet. To state that people should place a microphone at an arbitrary distance of 1 meter is a flawed assumption and does not consider the manufacturer's design objectives. Doing this would totally screw up the response using this device! This is why Dunlavy invested in two anechoic chambers! And who says 1-meter is the optimum position as though it is written in stone and why ? DEQX have been advocating this procedure for years along with using linear-phase filters with all of their pitfalls. It is little wonder nobody in the hi-end audio industry uses a DEQX to design a speaker. It's nothing more than a pipe dream !
#7
News Updates / Latest Firmware Update - 24080...
Last post by Tranquility Bass - August 05, 2024, 07:32:50 PMPlease click on the following link for the latest firmware updates for the UP1,UP2 and UPP. (You need to be a registered member of this forum to access this page.)
https://analog-precision.com/forum/firmware-updates/firmware-update-24/
https://analog-precision.com/forum/firmware-updates/firmware-update-24/
#8
Ultimate-Preamplifier by Analog-Precision / Re: Please Read !
Last post by Tranquility Bass - July 12, 2024, 09:16:56 AMHey Xawo, you seem to be lost mate. Perhaps you're looking for your buddy from DEQX ? The last I heard he had flown all of the way to Vietnam to one of my clients to listen to my Preamp. Wonder how he found him ? Maybe a posting on my facebook page. Hmmm Recently another one of their buddies phoned me up also allegedly interested in our preamp but I had to decline because we don't have any to sell as they are all being diverted to the active speaker we are developing. I think it was more of an intelligence gathering exercise. I didn't really want to talk to him because of his close association with DEQX but someone else had already made an arrangement on my behalf without consulting me first and that was one hour of my life I won't get back. On reflection it sounded like a fishing expedition to gather intel which is what DEQX do, not to mention send their buddies to gate crash other peoples pre-orders and big note how linear phase filters sound soooo gooood. Notice how DEQX never appear on forums instead sending their foot soldiers to do their dirty work for them 
https://www.diyaudio.com/community/threads/hi-end-dsp-based-multi-channel-integrated-preamp-crossover-dac-project.264743/page-67#post-5934654
That sounds so contrived Well I have got bad news for you. I have three good reasons why you should AVOID using a linear phase crossover. This should change your mind
https://analog-precision.com/forum/news-updates/why-we-would-never-use-a-deqx-to-build-a-loudspeaker-!/
Recently another one of their buddies phoned me up also allegedly interested in our preamp but I had to decline because we don't have any to sell as they are all being diverted to the active speaker we are developing. I think it was more of an intelligence gathering exercise. I didn't really want to talk to him because of his close association with DEQX but someone else had already made an arrangement on my behalf without consulting me first and that was one hour of my life I won't get back. On reflection it sounded like a fishing expedition to gather intel which is what DEQX do, not to mention send their buddies to gate crash other peoples pre-orders and big note how linear phase filters sound soooo gooood. Notice how DEQX never appear on forums instead sending their foot soldiers to do their dirty work for them https://www.diyaudio.com/community/threads/hi-end-dsp-based-multi-channel-integrated-preamp-crossover-dac-project.264743/page-67#post-5934654
QuoteSecond, what I really like about my DEQX crossover at the moment is the implementation of linear-phase crossovers (FIR). The software treats it just the same as Linkwitz or Butterworth crossovers. Just choose it from the list, that simple. All other DSP solutions so far expect you to be a DSP expert to be able to implement linear phase crossovers. I was looking for this in audioweaver but so far have not found it yet. Maybe I'm missing something. Now before anyone likes to discuss the downsides of linear phase crossovers and why I would want them but there is only one simple answer: Because it sounds better in my system and except from linear phase crossover I can't think of anything why I would need the amount of DSP power that is on offer in the Ultimate Preamp
That sounds so contrived
Well I have got bad news for you. I have three good reasons why you should AVOID using a linear phase crossover. This should change your mind https://analog-precision.com/forum/news-updates/why-we-would-never-use-a-deqx-to-build-a-loudspeaker-!/
#9
Ultimate-Preamplifier by Analog-Precision / Re: Please Read !
Last post by Tranquility Bass - July 03, 2024, 12:48:40 PMQuote from: Xawo on September 18, 2021, 09:13:19 AMWaiting for more established sales and reviews. Its a lot of money to spend on product that cant audition first.
Here in HK DEQX have dealer and support. Can I have link to Audio Sciene Review website review of UP? I didn't find one.
I not understand about comments about gullible customers. DEQX specialist said if I buy product now I can return and upgrade when new product available.
I just ask these questions before I spend big money on preamp for help.
Since I decided to hide the thread about the new active speaker guess who logs on to have a good old looksy ? The neigh sayer from DEQX headquarters. How are you going over there Curly ? I see you have been scouting around on the forum of late. Hmmm
Got your new DEQX yet ? You certainly had to wait a long time for it. I hope the wait was worth it ! Someone on ASR said they couldn't wait any longer and instead decided to sell their existing DEQX and use Camilla DSP instead Sorry I couldn't sell you a current generation UP2/UPP Preamp as I have had to divert all parts and boards for use in the new active speaker we are developing. It's a much more integrated solution than the DEQX, rather than an after thought
PS. Don't forget to report back your findings to DEQX headquarters - they are waiting for the phone call
Have a nice day
#10
Performance and Measurements / Re: Why we would never use a D...
Last post by Tranquility Bass - May 28, 2024, 10:52:46 PMBelow is NHT XdS driven by XdA (DEQX), equalized step response on tweeter axis at 50" (5ms time window, 30kHz bandwidth).
Note the extreme pre-ringing from the individual driver step reponse as predicted by the use of a linear-phase filter. Unless the cancellation of these two responses is perfect the pre-ringing will leak through and this is most likely to manifest itself off-axis. Also to get to this response the reponse from the two individual drivers need to be added together but studying the corrected responses in isolation reveals that the summation is imperfect and the summed response does not sum to a clean step response compared to the passive Dunlavy SC-VI's below. Tsk, tsk,tsk.... !!
Below is the Dunlavy SC-VI, step response on tweeter axis at 10' (5ms time window, 35kHz bandwidth).
As one can see from above the passive crossover Dunlavy speaker design more closely aproximates a step reponse than the fully active DEQX corrected DSP design. Sometimes less is better ! In fact I don't believe there has been a better measured step response on Stereophile from any other passive loudspeaker vendor since !
Note the extreme pre-ringing from the individual driver step reponse as predicted by the use of a linear-phase filter. Unless the cancellation of these two responses is perfect the pre-ringing will leak through and this is most likely to manifest itself off-axis. Also to get to this response the reponse from the two individual drivers need to be added together but studying the corrected responses in isolation reveals that the summation is imperfect and the summed response does not sum to a clean step response compared to the passive Dunlavy SC-VI's below. Tsk, tsk,tsk.... !!
Below is the Dunlavy SC-VI, step response on tweeter axis at 10' (5ms time window, 35kHz bandwidth).
As one can see from above the passive crossover Dunlavy speaker design more closely aproximates a step reponse than the fully active DEQX corrected DSP design. Sometimes less is better ! In fact I don't believe there has been a better measured step response on Stereophile from any other passive loudspeaker vendor since !