A new DEQX review:
http://www.positive-feedback.com/Issue79/deqx_premate.htm
http://www.positive-feedback.com/Issue79/deqx_premate.htm
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I originally made a number of indoor measurements & the closest I managed to the result outdoor was by lifting the speakers onto a small table in the centre of the room so the driver set was roughly equidistant between floor and ceiling with the mic about 3' away and centred between the drivers but slightly higher towards the tweeter (which will be in line with your head during normal listening). Place the speaker at the extreme front edge of the table surface, even better if you have something the same width as your speaker to minimise reflections. Place as much soft material as is practical on the floor between speakers and mic, ie a mattress if possible or several sun lounger cushions etc. You will not completely kill the floor reflections and there will be some from the ceiling but it does help The measurement should show a point where reflections become apparent (very clear and distant outdoors but much less so in a room) and where the truncation can be made. For me, no matter how good an indoor measurement, the resulting calibration never managed to lose a slightly unnatural or hollow sound. Measurements outdoors, although a massive PITA, is so much more accurate if everything is done properly. Patience really pays off with DEQX - if you are inquisitive, make several attempts, take advice from Nyal and with experimentation it will be worth it in the end. You have the flagship processor so make the most of it and good luck! |
Andrew (Drewan77) & Bombaywalla, thanks for your kind comments. And Bruce (Bifwynne), thanks for the suggestion about putting pillows on the floor for the speaker measurements. That is also suggested in the manual, and I'm planning to do it. I should have some time tomorrow to start playing with measurements, although I suspect I won't have anything meaningful to report for a few days or more. Regarding the manual, for my HDP-5 the 38 page user manual and the 143 page calibration ("installers") manual were on the calibration software CD. Similar if slightly earlier versions of those manuals can be downloaded from the DEQX site. (Click on the "owners" tab near the top of the home page, then "upgrades," and then scroll to the bottom of the page that appears). I printed out the manuals, 3-hole punched them, and put them in a loose-leaf binder, which for lengthy documents such as these I find preferable to viewing a pdf on a computer (unless I want to use the pdf reader's "find" function to look for a specific term). Content-wise, IMO the manuals are informative and reasonably well done. (Perhaps it was a different story some years ago when Psag and other long-term users purchased their units). Although the online session I had with Nyal Mellor was certainly a valuable supplement, in part because of suggestions he made that were in the direction of greater conservatism in the corrections than the calibration manual would seem to suggest. Bruce, a question for you: When the DEQXpert people calibrated your speakers, how far did they end up placing the microphone from them? And if you know, how many milliseconds after the direct sound arrivals did they place the point at which subsequent arrivals were windowed out? The reason I ask relates to the relatively large physical spacing between some of your drivers, which based on pictures I've seen I suspect is around 3 feet between the lowest of the four woofers and the tweeter. On my speakers, also, the two woofers are a significant distance (about 15 inches) above and below the two tweeters, which in turn are about at listening height. The reason I started thinking about that is it occurs to me that the greater the physical separation between drivers, the greater the distance should be between the speakers and the measurement microphone, which in turn (assuming the speakers are not measured outdoors) will necessitate shortening the duration of the measurement window (prior to arrival of the first reflections), which in turn will raise the minimum frequency that should be corrected and/or reduce the accuracy of the corrections. The reason I'm envisioning for that is not related to off-axis dispersion of the drivers, since the mic is placed at the level of the drivers which presumably have the narrowest dispersion (i.e., the tweeters). What I'm envisioning is that with the mic placed at tweeter level, the closer it is to the speaker the greater the difference will be between the distance from mic to tweeter and from mic to other drivers. And if the drivers are widely spaced, the amount of that path length difference will be significantly different than the difference between those path lengths as they exist at the listening position, due to the shallower angle between those drivers as viewed from the listening position. In other words, it seems to me that if drivers are spaced relatively widely, and the mic is not moved correspondingly further away from the speakers during the speaker calibration process (with the downside of shortening the "window," and hence the accuracy and/or low frequency extension of the corrections), the speakers may be corrected for a timing error that won't exist at the listening position. I've done some geometric calculations for the 15 inch distance between the woofers and the tweeters on my speakers. At a 4 foot measurement distance the path length differential between the distances of the mic to the tweeters and the woofers is 0.18 feet. At my 11.5 foot listening distance that differential is only 0.06 feet. The difference between those differences is 0.12 feet, corresponding to a propagation delay at the speed of sound of about 0.11 ms (milliseconds). Which would seem to mean that the DEQX will correct for a 0.11 ms timing error that won't exist at the listening position, if my speakers are measured at a distance of 4 feet, and a somewhat larger error than that in the case of your speakers. The planes of the baffles on my speakers, btw, are such that the woofers are mounted a little forward of the tweeters and mid-ranges, presumably to help with time alignment. But that is unrelated to the point I am describing. Also, to provide a bit of perspective on a 0.11 ms timing error, that would be readily perceivable on the step response graphs JA provides with his speaker measurements in Stereophile, those graphs having a time scale of 1 ms per major division. One of the purposes of those graphs being to provide some idea of the time coherence or lack thereof of the speaker. Apologies for the long-windedness of this post, but I hope it is clear, and that is the background for my question about the measurement distance the DEQXperts chose to use with your speakers. Best regards, -- Al |
Unsound, when I speak of the DEQX as being an "artifact," I am only saying that it is a component that is stuck in the signal path. Period!! Of course, its very purpose and function is to change ... and quite significantly so ... the signal when engaged. Stated differently, IMO, the best scenario is one in which one's speakers are already *perfectly* time aligned and the room is perfectly neutral. Ergo, no need for the DEQX at all. But alas ... such is NOT the case with my rig and I suspect with most others' rigs. Bottom line: 2 steps back and 5 steps forward. Net positive sum improvement, which I believe the DEQX has achieved for me. @Al ... just an fyi. When Larry the DEQXPert time aligned my speakers, he had me shove a bunch of pillows or seat cushions in front of my speakers. The pillows attenuated the fist reflective floor bounce off the woofers. That may help with your speaker correction results. @Psag ... your anecdotal experience is consistent with what Al reports. Your results are indeed amazing and good to know since I too am a DEQX owner. |
Al, Thanks for your report on your experiences with the HDP-5. I like your step-by-step approach of evaluating the bypass mode in comparision to your previous set-up. I look forward to hearing what differences you hear in bypass mode once you have had a chance to listen and compare for a longer stretch. |
Congratulations on your purchase Almarg - I think it's very good to do the first run through of the measurement and calibration process in situ. I dragged the system outdoors when I first did this but realised a few days later that I should have done a few things differently so had to repeat it again. You will learn a lot during the first few weeks and it does take time to understand everything fully |
I'd like to know about the artifact as well. Before relying on the DEQX as the 'brain' of my system, I needed to convince myself that it was virtually transparent in bypass mode. In bypass, the room and speaker corrections are left out, but the A/D and D/A conversions are performed by the DEQX. I compared my setup with and without the DEQX, keeping my analog preamp in the loop for both. I was unable to hear any sonic degradation being introduced by the DEQX. This is amazing to me. |
Hi Bruce, Yes, I've been following the ARC KT-150 upgrade threads to some extent, particularly including your posts. Glad it appears to be working out well. And yes, at this point I'm satisfied with the transparency of the DEQX, and I'm ready to move on to the measurement and calibration/correction processes. As I indicated, though, progress may be a bit slow in the coming weeks, due to other activities. Also, before moving the speakers to the center of the room for the measurements (outdoors measurement being a non-starter in my case, as it was in yours), I'm planning to first dry run the entire process with the speakers in their normal position. That way I won't risk moving the speakers to the center of the room and then back, finding that I've screwed up or at least not done things optimally, and then having to move them again. Even though the bases and footers I have the speakers on only raise them a bit less than 5 inches above the floor, I don't relish lifting/sliding their 108 pound weight off of those bases, and subsequently raising and maneuvering them back on. Best, -- Al |
Got is Al. So, at this point, have you completed your empirical assessment of the DEQX's D/A and A/D "pass-through" transparency?? Al ... as I have already posted a couple of times, a respected dealer once told me that sometimes you have to take 2 steps back to go 5 steps forward. My point is simply that empirical observations re the DEQX's touted transparency aside, ... it's still an artifact. This may come off as a contradiction, but I believe the DEQX does something to the signal integrity on top of what it's supposed to do. Frankly, if I had my druthers, I wouldn't use it. But with my speakers, in my room, the DEQX adds a lot more than it takes. Life is about compromises. Regards and please keep us posted about your progress. Bruce P.S. -- Al ... You may have caught the thread about the Ref 150 SE upgrade. ARC upgraded the circuits in my Ref 150 to better accommodate the KT-150 tubes. Wasn't cheap, but I think there's a significant improvement in SQ. The upgrade is still in break-in mode, so I hope to hear some continued improvements. |
05-16-15: BifwynneYes, that's correct, Bruce. But a logical concern in using the DEQX in conjunction with a phono source would be the transparency of the A/D and D/A conversion processes that it inserts into the signal path, and perhaps also the transparency of its digital volume control function. Some of the experienced DEQX users posted comments earlier in the thread attesting to that transparency, but obviously before getting into calibrations and corrections I wanted to confirm that with my own system, recordings, and ears. As well as assessing the differences resulting from replacement of my preamp with the DEQX, and replacement of analog interconnections to my digital sources with digital interconnections, and substitution of the DEQX's DAC function for their internal DACs. Best, -- Al |
Al, please clarify/confirm what you are reporting. At this point, I think you are saying that your DEQX is being used in bypass mode ... no signal corrections yet. If so, presumably there should be little or no impact on the signal as it passes through the gizmo, which is pretty much what I am getting from your post. Btw, your dealer's cautionary comment about resisting over-correction is what Larry, the DEQXPert, told me. Please keep us posted about progress. Regards, Bruce |
An update: I received my new DEQX HDP-5 from dealer AcousticFrontiers.com a few days ago, slightly ahead of the schedule for this production run which DEQX had projected back in March. Installing the DEQX component in the system was straightforward, although time-consuming in my particular case because I canÂ’t access that or some of the other components in my system from the rear when they are in position, and also because of reconfiguration of many of the interconnections in the system that was necessary (as described in the next paragraph). But once that was done I was immediately able to listen to music via both speakers and headphones, using the DEQX in its as delivered bypass mode configuration. I then read through the user manual and the software/calibration manual, and installed and browsed through the calibration software on one of my laptops. As he does with all purchasers of such products, Nyal Mellor of Acoustic Frontiers then provided me with a free person-to-person webinar/software walkthrough via the Internet, which took 70 minutes and was highly informative and helpful. One basic point which was made clear was to avoid over-correcting, which can be tempting due to the power and flexibility of the calibration software. Or if one does want to try an aggressive set of corrections, to also create a more conservative set, store them in different profiles (which can be selected between at the push of a button on the remote), and compare the resulting sonics. I should mention that insertion of the DEQX into my system has involved changing several things at once. I have replaced my Classe CP-60 preamp with it. Due in part to the limited number of analog inputs provided on the HDP-5 (one balanced, one unbalanced), I am connecting the AES/EBU output of my CDP to the corresponding digital input of the HDP-5, rather than connecting the CDPÂ’s analog outputs to the preamp as before. My other critical source is phono (unbalanced), which I am connecting to the HDP-5Â’s unbalanced analog inputs. I am connecting two relatively non-critical analog sources (tuner and cassette deck) through a DB Systems line-level switchbox to the HDP-5Â’s balanced analog inputs, using XLR-to-RCA adapters. I am connecting my Squeezebox, which I and my wife just use for relatively non-critical Internet radio listening, to the HDP-5 via an Analysis Plus optical cable, rather than via analog as before. (My research seemed to indicate divided opinion as to whether the SqueezeboxÂ’s Toslink output or coaxial digital output is preferable, and given that and our relatively non-critical use of it I figured it would be best to use Toslink and avoid any possibility of ground loop issues or coupling of electrical noise into the HDP-5). Thus far I have spent several hours with both speakers and headphones assessing its transparency in bypass mode (i.e., with no corrections or calibrations applied), on both LP and CD, with mostly classical recordings (chamber, symphonic, and operatic), but also with some recordings from various other genres. On some recordings I noted little or no difference compared to my previous setup. On some I noted slight to moderate improvements in resolution of fine detail in complex passages, and in some cases also slight expansion of the soundstage. I did not perceive any loss of transparency of any kind on any of the recordings. IÂ’ll mention also that as might be expected sonics when listening to Internet radio are vastly improved as a result of using the DEQXÂ’s DAC rather than the one in the Squeezebox, despite the severe bit rate compression of the stations my wife and I tend to listen to. I will post further updates in the coming weeks as I proceed with the calibration/correction processes, but they will be somewhat slow in coming due to other things I will be occupied with in the near future. Regards, -- Al |
Drewan & Ptss, thanks for your latest comments, which are valued as always. Pete, a point to keep in mind is that a downside, or at least a potential downside, of the extraordinarily wide bandwidth of your Spectral equipment can be expected to be increased sensitivity to any RFI/high frequency interference that may find its way into the circuitry of those components, compared to components having more typical bandwidths. Also, as I pointed out earlier the PreMate, which was well reviewed by Kal and has been found to be beneficial in Bruce's (Bifwynne's) very high quality system, uses a switching power supply. Finally, it would seem understandable that the internal real estate and the additional power required to support inclusion in the HDP-5 of the touchscreen and its associated CPU and other circuitry could very well have necessitated going to a switching power supply. Best regards, -- Al |
Ptss, what you say is logical and I understand why this concerns you. I guess I am fortunate that my HDP3 uses the same linear power supply as the HDP4. However the PDC 2.6 I first listened to and the Premate others here refer to both have 'inferior' power supplies, nevertheless all seem happy so I guess it's a question of personal expectations or the different things each listen for. I recommend anyone who is concerned about this email Alan Langford and ask DEQX directly: alangford@deqx.com He has always replied to me, sometimes after several days and not always with a first response that answers my question but he is helpful. |
Bombaywalla, you and your comments are certainly respected. I lack tech knowledge and so must re-read these last posts. However Drewan I believe a "most refined" power supply is the basic requirement of a great product.My experience has taught that as your basic equipment, pre & amp, become of exceptional quality it is noise that limits the ultimate refinement of the music and to my ear it's very noticeable; not as noise per se, but as limiting dynamics,nuance and particularly the spatial presentation of the orchestra.I know how even minute amounts of noise have a significant effect in my Spectral & MIT system,as I have experimented & invested in quality power conditioning & isolating products which allow the ability to "cascade" complementary products in a very revealing & informative way.My Spectral DMC20 pre has a 'highly touted' separate power supply (which I came to feel was the units weakest link as I thought that a robust power supply should 'perfectly' isolate the effects of ac noise). My system reveals how insidious any electrical(perhaps also magnetically generated) noise interferes with the systems ability to render the magic of great sound reproduction. The DEQX is "an added link in the chain" which can only add noise!(then consider cabling). I can't help it - the more this is discussed the more I feel the move to the switching power supply is "only" about saving money. Transportation costs are becoming a more significant aspect of cost all the time. |
Hi Almarg, yes, you are correct - misstatement on my part. Sorry guys! indeed the linear power supply operates at its designed output voltage (which is over-designed to ensure it will accommodate the max program material voltage) & the extra power dissipated will be (power supply voltage to amp output stage - voltage of program material) * current. And, correct again, the power amp output stage mostly operates at the average voltage of the program material. |
I have just read these posts about the DEQX power supply and yes, I too had noticed the apparent 'downgrading' from the supposedly superior linear power supply in the HDP4 & HDP3 models In support of Nyal, he also gave me some excellent advice when I was setting up my DEQX back in 2012 even though I am back in his 'mother' country and not a USA customer. He seems a true professional to me I have a suspicion that the reason for his evasiveness is that he doesn't actually know and would rather not give a definitive response without knowing the facts. Whilst I absolutely endorse the products, most times I have emailed the manufacturer themselves a direct question I have received a (late), oblique or non-answer so maybe Nyal has the same experience? Their one major weakness appears to be 'retail' customer interaction, it may be different for the pro or OEM market I also guess that listening differences in power supply would probably be very small in real world listening rather than worrying about specs alone. I have heard a system with the original PDC 2.6, an older Premate, the HDP3 and a different system with an HDP4 and all share the same remarkable transparency, clarity, imaging and realism I also know from another European manufacturer that legislative bodies seem have an ever tightening influence on the types of PSUs being acceptable so possibly DEQX are reacting to this in the HDP5 |
Yes, an excellent post by Bombaywalla, and an excellent response by Michael (Swampwalker). Thanks, gentlemen! I am in full agreement with both posts, aside from what I believe is an inadvertent and minor misstatement in Bombaywalla's post: A linear power supply is expensive from a power dissipation perspective - you have to design its max voltage for the max peak voltage of the program material but in normal operation the linear power supply operates mostly at the average voltage of the program material. The difference in the peak & average voltage is dissipated as heat. Of course, you don't know what the max voltage of the program material is so you have to over-design further leading to more heat dissipation.Shouldn't it be the output of the amplifier that has to operate mostly at the average voltage of the program material, not the output of the power supply? With the difference between the average output voltage and the voltage supplied to that stage (which as you indicated has to provide headroom relative to the maximum anticipated output voltage), multiplied by current, corresponding to the heat dissipated in the output stage, not the power supply? Although the heat dissipated in the power supply will also vary with current demand. And although there are a few amplifier designs in which the output voltage of the power supply is actually varied among a number of discrete levels as a function of signal level, some of Bob Carver's older designs being examples. Again, though, an excellent and informative post. Thanks! Best regards, -- Al |
Well said, Bombaywalla. In audio as in many other technically complex fields, "it depends" or "maybe" is often the correct answer. We all hunger for yes and no answers but there is reason why "the devil is in the details" is a well-worn phrase. I know nothing about output ripple (although I'm pretty sure it's bad). What I do know is that several of the designers of products I admire devote a lot of attention to power supply design and execution. In my technically ignorant opinion, it's one of the reasons why the idea of buying an amplifier based on weight, as crazy as it sounds, is not such a bad idea. Good transformers and power supplies are usually pretty heavy, so all other things being equal (not comparing Class D to Class A, and normalizing for the weight associated with "machined form a solid billet of unobtanium"), there is a positive correlation between amp weight and SQ. IMO. |
03-24-15: PtssI try to address everyone by their chosen moniker without abbreviating as a mark of respect to that person. doesn't cost me anything - i use ctrl-C & ctrl-V to accomplish that rather than typing the moniker. Saves time & makes the other person happy that i addressed them as they want to be. but if you are averse to typing, sure. true. but in audio, it's all about the sound quality even when manuf use cheap components because even those cheap component audio manuf know that the human ear is very sensitive to distortion & if their gear doesn't meet the min requirements of the human ear not hearing distortion, their gear is not going to sell. So, it's not like an automobile that uses cheap components that break in 1-2-3 years vs. 10 years because in such a case (autos) you can still sell the product & not have the consumer come back for a long while. OTOH, in audio, if you have unacceptable distortion, one listen & the consumer will be out of the door looking for something else & the audio manuf will have a zero sale. so, yeah, audio manuf are pressured to make things newer, smaller, cheaper but distortion has to be kept below the average-Joe's hearing level. Also, just to point out - the "newer" fad is very much an American/USA thing. In other parts of the world, "newer" is not always better & once people are satisfied with the performance of whatever piece of equipment they have, they don't necessarily get an itch to switch it out with something newer. In the USA they seem to have this itch pretty badly. Different culture..... Loaded question. ;-) The correct answer is "depends". Linear power supplies have been around for a long time so their hardware has been in production for a long time as well. Plus a lot of the hardware for a linear power supply is also used in industrial applications thereby giving it the economies of scale from a pricing stand-point. To make a low AC ripple, high current, fast transient response linear power supply is not an easy task. It requires some careful design, careful layout esp. of the grounds & some expensive components. To take it further, some audio manuf are using a regulated linear power supply. And, this is an even tougher job esp. when the bandwidth of the regulated power supply is to be large (> 100KHz). There are some audio manuf who have a 1MHz regulated power supply but it's relatively low current (3-5A) & used with front-end components. You'll be asking why 3-5A when front end components often using 1A or less? It's the dynamic headroom required when you have large signal variations in the program material that suddenly draws a lot of current from the power supply. This momentary current draw can be very high & the power supply needs to support it otherwise the music loses its sparkle. The linear power supply can be made cheap & you see this in a lot of power amps in the market where you have high wattage but with very little current delivery to support those watts meaning that such high wattage amps cannot be used with difficult speaker loads. Cheap linear power supplies will also squash the dynamics in front-end components sucking out the life of the music. Linear power supplies can be made very expensive like the ones you see in high wattage, high current power amps that weigh a ton. You see expensive linear power supplies in 2-box or multi-box preamp units. A linear power supply is expensive from a power dissipation perspective - you have to design its max voltage for the max peak voltage of the program material but in normal operation the linear power supply operates mostly at the average voltage of the program material. The difference in the peak & average voltage is dissipated as heat. Of course, you don't know what the max voltage of the program material is so you have to over-design further leading to more heat dissipation. SMPS power supplies have been around since the 1960s but used extensively in places other than audio. All power supplies in airplanes are SMPS - efficient & light-weight (compared to a linear power supply) where weight is a big issue. Their harmonic distortion performance for audio probably sucks but who cares in that application. So, it can be made cheap - there are hundreds of planes manuf each year & each plane uses many, many SMPS power supplies. For audio applications, harmonic distortion is paramount so the SMPS output spectrum has be cleaned up so that you have vanishing low (something like -120dBc) distortion. That takes a lot of effort - good design, careful layout especially separating the analog & power/switching grounds and some expensive components that have low ESR/DCR such that the output ripple is low. So, a SMPS is a complicated circuit that had a lot of failures initially for the audio application because people just didn't understand how it worked & how to reduce its output distortion. That has changed for the better & continues to evolve. 1st you used to see class-D amps with linear power supplies. Now you are seeing class-D power amps with SMPS. These are not necessarily cheap & the best are very expensive. It takes some good amount of engineering to keep the SMPS (located in the same chassis as the amplifier stage) from spraying high freq noise into the amplifier. You will now say " the noise is high freq so it's out-of-band w.r.t. to the audio so why should i care?" The answer is that all electronic components have some non-linearity (nothing is linear from DC - infinite frequency) & this non-linearity will respond to the hi-freq spurious emitted by the SMPS & will mix it down into the audio bandwidth. Once that happens the distortion looks just like an audio/program material signal & is impossible to separate. When this happens, the life of the music is simply sucked out. To avoid this, takes some concerted effort. So, a SMPS can be made cheap & it is also expensive to make. Now you know why the answer is "depends"!! ;-) hope this helps...... |
Thanks, Pete. I appreciate your comment, and the nice words. And Bombaywalla, thanks also for your good comments. I would place myself somewhere in the middle ground between being overly trusting and overly cynical, and I try to judge each case on its own merits without bias in either direction. As you (Pete) observed, I tend to be pragmatic. In this case, adding to my confidence is that based on the exchange I had with him I'm pretty certain that Nyal has not yet sold or possessed any HDP-5's. Assuming that is the case, he would most likely not be in a position to respond either way to my question. And in fact in looking at the websites of the various dealers listed at the DEQX site I had found that none of the ones in the USA make any reference to the HDP-5 being available. I found just one dealer, in the UK as it happens, indicating it as being in stock (presumbly from the first production run, bugs included). And several additional factors add to my confidence: First, the PreMate which Bruce (Bifwynne) purchased, and that Kal and John Atkinson reviewed, uses a switching power supply. Perhaps some or all of the earlier models that are being used by the more experienced DEQX users who have been participating here do as well. Second, as I indicated what I will be purchasing will be from the second production run, which is explicitly stated to be incorporating some needed "corrections." And, finally and perhaps most importantly, Nyal offers 30-day return privileges, less only two-way shipping. Thanks again. Best regards, -- Al |
I agree, in general, that when a manufacturer or its representative is asked a direct question re. a change (such as use of a SMPS in the latest rev) & the subsequent answer avoids answering that question, that is not inspiring & leads the mind to think that something's being hidden. Maybe Almarg can press the issue at a later date when he's ready to purchase the HDP-5? OTOH, SMPS power supplies for use in power amps have made good strides in the overcoming their output noise issues (that would increase distortion in the music signal path & wreck performance). We see this evidence in many amps today - Anthem's Statement M-1 mono, Benchmark's AHB-2, Belcanto amps, Jeff Rowland amps & the quite popular Ncore 1200 series amps - just to name a few. So, the technology of low-noise SMPS for audio applications is out there; whether DEQX has accessed it for their HDP-5 is the question that needs confirmation. It seems to be a reasonable assumption that they have but we know quite well where assumptions can lead us sometimes!! ;-) I also think that DEQX wouldn't do something regressive to ruin their highly touted HDP-4 & Premate by putting a noisy SMPS in the latest HDP-5 but who knows sometimes manuf do things that they think are progressive only to be told by the user community it's regressive.... I agree with Almarg that it's a safe bet to think that the HDP-5 has a quiet SMPS but reading/hearing it from the manuf rep would have a reassuring effect... |
Hi Al, I appreciate your comments re-"Neither of his subsequent responses made reference to that question. His many posts that I've seen at various forums are confidence inspiring, and I feel safe in assuming that if he was aware of any negatives about the new design he would have mentioned them." My main take from this is you are a trustworthy person. However I can't concur. My business experience, although limited,as everyone's, drives me to uncertainty about it. When people have addressed an item I have found they are very open to confirm it, with pride in the improvement. Avoidance never gives me confidence-from anyone. I'm from Missouri(Newfoundland in Canada :-) Always a pleasure to review your pragmatic informative posts. Take care. Pete |
Hi Roscoe, In my initial email to Nyal I said: ...if you should happen to be aware of any issues which might result in the performance of the HDP-5 being inferior to that of the more mature HDP-4 I would of course appreciate being apprised of them. I realize that the HDP-5 utilizes a switching power supply while the HDP-4 has a linear supply, but I assume the design is well implemented and that is not an issue.Neither of his subsequent responses made reference to that question. His many posts that I've seen at various forums are confidence inspiring, and I feel safe in assuming that if he was aware of any negatives about the new design he would have mentioned them. Best regards, -- Al |
Unsound, as far as I am aware DEQX does not make power amps, class D or otherwise. And I've seen no indications that HDMI inputs are or will be incorporated in any of their products. Regarding 24/192, in JA's measurements writeup that was presented in Stereophile in conjunction with Kal's review of the PreMate it was stated that: The USB input accepted 24-bit data with sample rates ranging from 44.1 to 192kHz, including 88.2 and 176.4kHz. The TosLink input accepted data with sample rates up to 96kHz, and the AES/EBU input sample rates up to 192kHz. However, the DEQX Calibration app (v.2.93), running on a Windows XP machine, indicated that 192kHz data were downsampled to 96kHz, and 176.4 down to 88.2.... Though the PreMate will accept 176.4 and 192kHz datastreams, it appears that it downsamples them to half those rates before the data are presented to the DSP section, then finally the DAC. So no, there is no true bypass.... Running powerful DSP at 4Fs sample rates is very consuming of resources, so this compromise is not uncommon. It is likely that the benefits of the DSP correction outweigh the potential drop in sound quality due to the downsampling.Best regards, -- Al |
Hi Bruce, The revisions weren't specifically indicated, and it appeared that Nyal was just relaying information he received from DEQX which in turn didn't go into a lot of detail. But it sounded like the revisions were most likely just bug fixes specific to the HDP-5. I suspect they had no applicability to the more mature models. Best, -- Al |
Al. did Nyal mention whether the revisions would be made to the rest of the product line. As you know, I bought the Premate in September. I wonder if the revisions affect the Premate. Also, did Nyal tell you what the revisions are? This reminds me of the early days of PCs when Intel was constantly upgrading its CPU chips from the 286 to the 386 to the 486 to the Pentium and so forth. By analogy, I think DEQX is still in its early development stage and who can say where it will wind up. |
An update re my situation: I had indicated a while back that I was planning to order an HDP-5 around this time. Last night I contacted Nyal Mellor of AcousticFrontiers.com, who is a DEQX dealer having extensive specifically relevant expertise. (He is also an Audiogon member, btw, as "acousticfrontiers," as well as being a participant in various other forums). He indicated that DEQX is currently implementing some revisions to the initial HDP-5 design, which will be incorporated in a production run that will be available in the USA approximately mid-May. So I'll be waiting until then to place my order. Nyal also pointed out that he has some DEQX-related videos on YouTube, which I haven't yet watched but I certainly will. Best regards, -- Al |
