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    Reality Quest: Power and Digital Audio with the Sean Jacobs DC4 and Sound Application PGI TT-7 (Part 1 of 2)

     

    Reality Quest: Power and Digital Audio with the Sean Jacobs DC4 and Sound Application PGI TT-7 (Part 1 of 2)

     

     

    A hundred years ago at the start of the pandemic, I had a few words to say about the Taiko Audio SGM Extreme digital music server. 

     

    In that piece, I detailed my high level strategy and hypothesis for digital optimization:

     

    • First Law: Invest in cabling, power, and digital hygiene to do as little harm as possible (directly or indirectly) to the DAC’s clock, ground plane, or reference voltage plane
    • Second Law: Invest in a digital endpoint that moves bit perfect digital data from ethernet to a USB DAC with as little variability and as much timing and signal integrity as possible (aka, as close to precision real time data streaming to DAC as possible)

     

    The Extreme delivers on the Second Law of Digital Audio to a level way beyond anything I have ever heard, and has only improved during the last 100 pandemic years (look for a future Part 6 to my Extreme review later this Spring). 

     

    Any interesting side effect of pushing the Second Law to the Extreme (ouch) is that it has made it incredibly easy to discern the impact to sound quality from any other change in my system. With this clarity, it was finally time to revisit the First Law of Digital Audio (“Do No Harm To Thy DAC’s Clock, Ground Plane, and Reference Voltage Plane”), and see if better power could make things better.

     

    For a couple years now, I have had the very good fortune of having a custom Sean Jacobs DC3 power supply powering my Chord DAVE DAC. It completely transformed what I already considered the finest DAC I’ve ever heard, bringing a level of dynamics and control and spaciousness and reality that I had never heard outside of a live performance. Later, I added a dedicated 30A circuit with 10-2 Romex to the party and a Topaz ultra low capacitance isolation transformer, and all this awesome just got awesomer.

     

    So when I heard that Sean had released his new DC4 power supply, I reached out to see if I could arrange a loaner for review. He graciously agreed, and in doing so gave me a good excuse to revisit the First Law in my system, and see what new truths were waiting to be found. 

     

    For good measure, since I was already breaking the seal on the First Law, it was long past time to put aside my well-practiced denial about power line conditioning and give the Sound Application TT-7 power line conditioner a proper listen. For many years, many trusted ears had urged me to audition Jim Weil’s Sound Application PLCs, but with the universal warning to not do so unless I was ready to purchase one. I resisted, mainly so I could get the rest of my system dialed in first. With the Second Law well in hand, it was time to set aside my denial and give the PGI TT-7 a proper listen. 

     

    Spoiler warning: all those that urged me not to listen to one unless I was ready to purchase one were absolutely right (wow!).

     


    Background on Power and Digital Systems


    First my usual caveat: Digital optimizations and hygiene in audio can be a contentious topic (bits are bits, right?). Rather than debate mechanics, I am sharing my experiences in my home with my equipment and my local power grid with my ears and my biases and my aspirations for connecting emotionally to remarkable musical performances. Almost certainly yours will vary. Hopefully my experiences are helpful to you, but if not, that’s OK too.

     

    As I noted in my Extreme review, any time I have inserted a better/faster DC power supply (Paul Hynes SR4, Uptone Audio UltraCap LPS-1.2, LDOVR DXP supplies, etc) that delivers well-regulated voltage under very dynamic current loads, sound quality has improved. Similarly, better conductors and better shielding consistently improves sound quality, as does reducing mechanical vibrations on power supplies and digital components.

     

    So what is a possible basis for this? Digital systems are inherently switching systems, with current being switched on and off potentially billions of times a second. Like a light switch, every switch causes a surge in current, which then gets turned off when the switch turns off. The job of the power supply is to keep a perfect reference voltage (“On”) and perfect reference ground (“Off”). In the real world, no power supply is perfect, and it lags in how quickly it can respond to changing current demands. That lag can impact the reference voltage and the ground plane. In a DAC, that can be particularly bad, since the digital to analog section can be impacted by this noise, making it audible.

     

    DAC designers go to great lengths to filter or isolate this induced noise, but there are practical limits based on cost targets, availability of components, size/heat, etc. However, if there were no pragmatic restrictions, the ideal power supply would have perfect voltage regulation, be infinitely fast with an infinite reserve of instantaneous current, a perfect ground, and wiring that has zero impedance (resistance, capacitance, and inductance).

     

    In practice, nothing has zero impedance or unlimited instantaneous current capacity, so choices must be made, and accommodations made elsewhere in the design for the pragmatic realities of any given power supply.

     

    For example, the stock Chord DAVE DAC (>$10,000, so no slouch on the available budget for power supplies) uses the XP Power ECM40UT33 (~$40 part) for its internal power supply. I’ve read reports that more recent DAVEs use the EOS Power LFWLT40-3002 (a ~$18 part). 

     

    Of course, that is only part of the picture.The power supply is only part of the power network for the DAVE, with gobs of filtering and voltage regulation engineered into the DAC itself. Since we can’t (easily) hack the DAC printed circuit board to tweak power, what can we do to improve the key areas where power makes a big difference to a DAC?

     

    John Swenson, designer of first-class products for Uptone Audio and Sonore among others, has written extensively about power supplies and their impact on digital audio. His main areas of focus have been leakage current, and output impedance. 

     

    For leakage current, John has focused our attention on high impedance leakage current (an issue with switching power supplies, like the SMPS in the Chord DAVE), and low impedance leakage current, which impacts both switching supplies and linear power supplies. John argues that leakage current can cause voltage variations across the ground plane, causing jitter.

     

    For output impedance, John has focused on output impedance as a function of frequency. The lower the output impedance, the better a power supply can deliver a stable voltage at different current levels.

     

    There are more subtle characteristics as well. In an extremely informative post, Rob Watts (designer of the Chord DAVE, and decidedly not an advocate for power optimization for his designs) outlined the key areas of consideration for power when designing a DAC. This is a master class, and a roadmap to power optimization for DACs, which because of its importance and relevance, I am quoting in full here:

     


    RF noise. This by far is the most important thing in a PSU and analog electronics; it's something I talk about a great deal. The problem is that analogue audio components are non-linear, and very non-linear at RF (and by that I actually mean 20 kHz to several GHz). When a random RF noise gets into active audio components, it distorts with the wanted audio signal and creates inter-modulation distortion - and some of the inter-modulation distortion has an audio component - audible random noise. What happens with this is when there is no audio signal, you get no inter-modulation distortion, hence no extra noise. When the audio signal increases, the inter-modulation products increases, and noise goes up - so noise levels becomes linked to the signal level and you get noise floor modulation. Now this issue is easy to measure, and taking steps to remove RF noise lowers noise floor modulation. Additionally, you can improve the analogue electronics open loop RF linearity too.



     

    The problem with noise floor modulation is the ear/brain is extremely sensitive to it, and certainly can detect levels of noise floor modulation that is below the ability to measure. My own tentative conclusions (or rule of thumb) are that one can hear levels of noise floor modulation down to -200dB - currently we can measure noise floor modulation at -180 dB, and Dave has zero measured noise floor modulation. In terms of SQ, if noise floor modulation is say around -120 dB (typical class D) you get considerable hardness and glare; at -140 dB its grain in the treble; below -160 dB then things sound much smoother with better instrument separation and focus. This continues until about -200dB (and perhaps even lower - reducing RF noise is not something that has an acceptable limit).



     

    But to get this level of performance required me to do many things; and part of that was the PSU system. I call it a system because it is lots of parts working together, with sources of noise within the DAC contaminating other parts. One source is the mains power, so this is dealt with a filter that starts at a few 100 Hz to several GHz - each PSU line (+15v,-15v,+5v) from the SMPS is individually filtered with a complex multistage filter. That covers RF noise initially, but every analogue part is individually regulated and RF filtered again. Moreover, each digital module is individually RF filtered too, as each digital part of a DAC is a huge RF noise generator.
     
    PSU impedance. The impedance of the power supply is crucial too as it can create distortion which is audible. The actual mechanism for distortion from an amplifier is due to the fact that an amp draws signal related current from the PSU; this current then creates a voltage drop in the power rails (an error) that is signal dependent; this error then is fed back to the amplifiers output by the amp power supply rejection ration (PSRR); the error then creates distortion in the output. For Class A it is second harmonic, for class B it is very serious HF harmonics extending to infinite harmonics. Now its very easy to design the amp to avoid this problem; simply use low enough output impedance PSU and an amp that has a large enough PSRR. It is easy to calculate your requirements; much more difficult to design a stage that meets those requirements. So with Dave I wanted no measurable effect from this; this meant a PSU impedance in the OP stage of 3 milli ohms, which would make this effect un-measurable at -180dB. And that's exactly what I achieve; loading the output stage shows no measurable PSU induced distortion at all.

     

    Reference supply. So far I have talked about the requirements for the analogue section; and this is an interaction between amp topology (sensitivity to RF and PSRR) against the actual levels within the PSU. So you could use a poor PSU with an amp that had amazing RF and PSRR or vice versa. My approach with Dave is to use both strategies - get the best innate isolation with the best filtering I could do. But there is a PSU where whatever happens on the PSU will be directly on the output and this is the reference PSU. Now nobody talks about the reference for two reasons - it is buried inside a DAC chip, and because people are not aware of how crucial this component is. The reference supplies the voltage that is used to create the analogue voltage (or current) output on the DAC, so clearly if that voltage changes it will have an immediate and 100% impact on the output. Normally, with a silicon DAC the reference presents a problem; noise on the reference will appear on the output, so making the SNR and dynamic range (DR) depend on the reference. Its actually extremely difficult to have a 120dB reference voltage on chip; so to overcome this they use a differential structure (balanced + and -). This means the reference noise, when its reproducing small signals is cancelled as it becomes common mode. So you get good DR figures from a poor reference. But when the signal becomes larger, the cancellation stops and you then see the reference noise and you get noise floor modulation - which is very measurable and very audible. It's one reason why chip based DAC's have large amounts of noise floor modulation.
     

     

     

    Rob clearly has made a HUGE investment in his designs to minimize any adverse impact from power issues. If he believes that the stock DAVE medical grade power supply delivers the best performance and further investment in power supply won’t have a material impact, who are any of us to say otherwise? 

     

    While there is literally no one in digital audio that I respect more than Rob Watts, on this my ears respectfully disagree. When provided with better and better power, the Chord DAVE scales beautifully (incredibly actually), and reveals a quality of dynamics and sense of space and relaxed naturalness that is otherworldly and must be heard to be believed. Both the Sean Jacobs DC4 and Sound Application PGI TT-7 not only have a place at this table, but are essential foundational elements to build around.

     


    BEWARE!! Here Dragons Dwell…


    Before going further, a reminder that what is described here is most definitely not supported nor endorsed by Chord or any DAC manufacturer. It involves opening the case (a no no) and replacing the power supply to the unit (a big no no). 

     

    Before attempting anything like this, please appreciate that you are likely voiding warranties, putting your equipment at risk, and potentially putting yourself at risk. If you are not comfortable doing so, or if you have ANY doubts about your skills and ability to work safely with electronic circuits and live power, please do not attempt any of these modifications to your system. 

     

    To very intentionally belabor the point, anything you choose to do is at your own risk. If you have doubts about whether you should attempt any of this, please do not attempt it!!! Frying your equipment or yourself simply isn’t worth it.

     


    Enter the Sean Jacobs DC4


    Note that the DC4 supplies can be spec’ed and leveraged in a variety of scenarios, not just to power the Chord DAVE (for example, Sean does offer a variant tailored to the Chord Blu2 transport, and Sean has been designing and building power supplies for Naim and Innuos and others for years). Depending on the voltages and number of voltage rails you require, each build is unique. 

     

    When I first approached Sean for a loaner DC4 to review, he suggested that given his workload and backlog, I work with @Nenon here in the US, who is licensed to build supplies based on Sean’s designs for the US market. For the purpose of this review, I requested a custom 3 rail DC4 with 5V, +15V, and -15V as required by the Chord DAVE, which @Nenon graciously agreed to build and provide for review.

     

    (Disclosure: I have no financial affiliation with Sean Jacobs, @Nenon, or anyone mentioned in this review other than as a customer who has purchased their products. Moreover, I have no commercial interest or affiliation in any of the vendors discussed in this review. Review units were provided without condition or expectation. My thanks to Sean and @Nenon for the opportunity to hear the DC4 in my system, and Jim Weil for the opportunity to hear the PGI TT-7 in my system.)

     

     

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    All Shiny and Chrome

     

    Physically, the DC4 (on the right) is considerably larger and heavier than my Sean Jacobs DC3 (on the left), but thankfully quite easy to move around. The Modushop case is upgraded from the DC3, with IsoAcoustics Gaia feet for vibration isolation and a Furutech gold plated IEC inlet.

     

     

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    Cracking the case, the build is gorgeous. From right to left, there is a custom wound 600VA transformer fully loaded with internal shielding and a stainless steel shell. The DC4 transformer is a better-spec version of the transformer used in the DC3, with a laboratory measured and selected core, precision wound windings for low mechanical noise, and the entire assembly has been potted in epoxy and a stainless steel outer can for mechanical isolation and shielding. For further mechanical isolation, the transformer assembly is mounted to the inner chassis via four vibration isolation mountings.

     

     

     

     

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    The transformer assembly is connected to three independent rectification and capacitor array (RECAP) boards, each with an updated design versus the previous generation DC3. In addition to higher grade components on the board and a gold plated printed circuit board, the DC4 RECAP boards sport four 10,000 µF Mundorf capacitors (versus two Mundorfs on the DC3) and improved filtering for each of the three voltage rails. 

     

     

     

     

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    The DC4 also includes three of Sean’s new CX voltage regulator boards (CX-REG), configured to 5V and ±15V (each rated to 5A continuous output). The regulator boards also sport gold plated PCBs and upgraded components compared to the DC3 (Vishay Z-foil resistors, Audio Note KAISEI capacitors, etc), an optimized circuit layout and star-ground management (vs the DC3), all resulting in reduced output noise and ground noise, with enhanced performance versus the DC3 design. 

     

     

     

     

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    Note that the CX boards in the DC4 have new built in circuitry to significantly improve noise rejection at low currents (up to 3A). The lower the current, the more effective the CX filter is. Interestingly, the CX filter can be enabled and disabled with a jumper on the regulator boards (it is enabled by default for DAVE configured units).

     

    With the Chord DAVE typically drawing ~1A on each of the ±15V rails and ~2A on the 5V rails, the CX filter should have a noticeable impact (more on this later).

     

     

     

     

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    All components are mounted to the case using vibration isolation materials, and the case is lined with vibration dampening materials on all sides (for these types of supplies, the transformer and large caps are particularly susceptible to vibration). All internal wiring is typically Neotech 7N OCC wiring with teflon insulation, although this particular review unit had been upgraded to use optional Mundorf silver/gold internal wiring.

     

     

     

     

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    On the output side, there is one connector for 5V and ground, and a second connector for ±15V and ground. This unit came with Sean’s standard Neotech 7N OCC DC umbilical, which combines the DC lines into a single Molex connector to be attached to the DAVE PCB. 

     

     

     

     

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    The umbilical contains clamping hardware for mounting to the DAVE case, with the 4 pin Molex connector mounting directly to the power connector on the DAVE PCB (the white connector in the photo above).

     

     

    The Sean Jacobs DC3

     

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    In comparison, the build of my circa early 2018 Sean Jacobs custom three rail DC3 supply is a bit more compact. This DC3 was configured with high current CHC-REG voltage regulator modules, so it is also capable of supplying 5A continuous current on each of the three ±15V and 5V rails (at least for short stretches).

     

    While this unit has a single output connector, the ±15V rails and 5V rails are separate from each other, and only join together at the 4 pin Molex connector that connects to the DAVE PCB (same as the DC4 cable). The DC4’s configuration is more robust with two output connectors, keeping the lines for the digital side (5V) and the analog side (±15V) separate until the connection on the DAVE PCB.

     

    Like the DC4, the DC3 uses a custom toroidal transformer with ESS (shielding between primary and secondary windings) and GOSS band (mu-metal wrap around the transformer to shield against emissions), but is of an older design than the transformer in the DC4. Unlike the DC4, the DC3 transformer does not have epoxy potting or the stainless steel can (for mechanical vibration control and shielding).

     

    Each of the three Schottky rectifier bridges in my DC3 feed two large 10,000 µF Mundorf capacitors (versus four Mundorfs in the DC4), which in turn feed three Sean Jacobs CHC-REG regulator modules. Two of these regulator modules are connected in series to give the ±15V rails and the third one is the 5V rail. 

     

    The smaller Modushop case is solid, but lacks the vibration isolation details found in the DC4 case. The umbilical with my DC3 is made from OFC (vs the Neotech OCC with the DC4).

     

    While the DC3 is a world class audio power supply, with the DC4 Sean looked to design the ultimate “cost no object” supply, elevating component, design, and build quality at every level. 

     

    Alas, the DC4 does come with a requisite ~3x increase in cost: US$7,300 as reviewed (with pricing in flux because of Brexit), versus what was at the time ~US$2,500 for the DC3 (DC3 for DAVE is now discontinued). 

     

    Compared with the DC3, the DC4 has improved circuit designs (for noise and performance), and significantly higher-spec parts to maximize performance. The assembly itself has also been optimized, with a significant pervasive focus on vibration isolation (including the premium IsoAcoustic Gaia footers), and premium connectors and internal wiring.

     

    As someone who had purchased a DC3’s to power a Chord DAVE back when this was more of a science project than a product, I was very excited to hear what Sean had come up with in his latest generation design.

     


    Installation (CAUTION!)


    For both the DC4 and DC3, installing them involves opening the Chord DAVE, and removing the stock switching power supply (please DO NOT ATTEMPT THIS unless you’re willing to void your warranty and assume all responsibility for any damage done to your system or yourself). 

     

    If you’re willing to void your warranty but do not want to install yourself, check with whomever is building your supply for you to see if they are willing to install the power cable for you.

     

     

     

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    The process to install the DC4 (and before that, the DC3) was straight forward, taking me about 20 minutes the first time, and less than 10 minutes subsequent times once I got to know where all the pieces are. More importantly for me, it is completely reversible.

     

     

     

     

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    To open the DAVE case, unplug the system and remove all the screws around the display, then move the faceplate and ring. This will reveal 4 additional screws. Only remove the bottom screw, DO NOT remove the top three screws (this mount the display to the top plate of the case).

     

    Next remove all the screws around the top left and top right of the case. This will free the top of the case from the bottom of the case, allowing you to remove the top.

     

     

     

     

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    To remove the top, gently lift the top (careful not to drop it, it is heavy!) to reveal a ribbon cable connecting the controls on the top of the DAVE to the main PCB of the DAC. Carefully disconnect the cable from the top, then fully remove the top from the unit and set aside.

     

     

     

     

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    Internally, the DAVE stock SMPS is mounted in the front left of the case (already removed in this photo). After confirming that power has been disconnected from the system, make a note of how the white 4 pin Molex on the far left of the PCB is connected (take photos!). The Molex is not keyed, so it is possible to plug in backwards and fry your DAVE. 

     

    Once you have the orientation of the Molex captured, carefully remove it from the PCB. Next, slide up to remove the power switch/inlet assembly from the back panel of the case (there is nothing holding it in place). Finally, carefully remove the 4 screws holding the SMPS in place, and remove the entire stock DAVE SMPS assembly.

     

     

     

     

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    To install the DC4 (or DC3), confirm that the DC4/DC3 is unplugged, mount the DC umbilical in the rear left of the case, and carefully connect the Molex connector to the DAVE PCB. 

     

    CAUTION!!!! The Molex connector is not keyed. It is possible to put in backwards (or displaced by one pin) and fry your DAVE PCB. Be very careful to note the proper orientation when you disconnect your stock DAVE SMPS, and double and triple check that you have the orientation right when you plug the Molex back in.

     

     

     

     

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    Once all is hooked up, carefully reconnect the ribbon cable to the top of the case, rest it securely to the side, and fire up the supply. If all goes well, DAVE will boot as usual. If not, immediately power down and figure out what went wrong. When you’re good, power off and unplug the supply, and put the top back on.

     


    Listening Impressions


    Time to put these supplies through their paces and see how they stack up. Like all components with these large Mundorf capacitors, it takes a LONG time for them to properly settle in, and the DC4 is no exception (I had very similar experience with my DC3 and my Taiko Audio SGM Extreme). That being said, you can’t have something like the DC4 in the house and not give it a listen right away!

     


    First Impressions – DC4 straight out of the box


    As I mentioned earlier, I have been using a DC3 with my DAVE for almost three years, so my first impression listening to the DC4 straight out of the box is compared against a well burned in DC3.

     

    Even without burn in (the Mundorf caps need a LOT of time to settle), the DC4 was clearly a step up from the DC3. Within the first 5 seconds of listening, I heard the characteristic bump in all the attributes that made the DC3 such a winner for me: control and viscerality of bass, the presence of the space, and a surprising increase in “relaxed naturalness” (something I’ve come to associate with a lower noise floor and better control). 

     

    One area I was expecting more (given my DC3 experience) was an increase in dynamics and detail, but my initial impression was that the fresh-out-of-the-box DC4 was being held back a bit. There was also a sense of some sound stage instability, but significantly less (based on my notes) than similar impressions I had when I first plugged in my DC3. 

     

    With my DC3, these dynamics and instability nits completely went away after running the unit for a month or so, so I had full confidence the DC4 would do the same (which it did, and then some). 

     

    Looking back to when I received my DC3, the improvement from DC3 (new) to DC3 (run in) was MASSIVE. Listening to a fresh out of the box DC4, if this is the performance I’m hearing before any burn in, I can’t wait to hear how much things improve as the supply settles in. Be patient with these caps, and your patience will be rewarded!

     

    True to form, after playing music through the DC4 + DAVE to Abyss headphones continuously for ~6 weeks (at least when I wasn’t listening to music) it VERY nicely settled in. All sense of instability was gone after ~1 week, and dynamics and clarity rapidly improved and just kept improving before settling out after ~6 weeks.

     

    With the DC4 well burned in after 6 weeks of 7/24 operation, it was finally time to pivot to critical listening.

     


    Stock DAVE SMPS versus Sean Jacobs DC3


    To reestablish a common baseline, I reinstalled my stock DAVE SMPS, plugged into a normal shared house electrical outlet with a stock computer power cord, and listened to music for several days. While the loss of viscerality and physicality of bass, resolution, and dynamics was immediate (and missed), I wanted to have this common baseline to incrementally step up the ladder and evaluate the incremental impact for each incremental change to my system.

     

    It had been almost three years since I had the stock DAVE SMPS in my system, so hearing the stock presentation did evoke no small bit of nostalgia (amazing how music and smells can sometimes take you to another time and place). After a couple days of holiday albums and favorites playing in the background, I had reestablished a baseline of my system with stock power and stock SMPS for the DAVE, so I was ready for some critical listening.

     

    Going through my standard test tracks with the stock DAVE SMPS and standard wall power, I was struck first by how different tracks presented so differently. The best recordings presented a good sense of space and physicality (that “realness” which is the experience I find so intoxicating) but still hinting at what is possible. Most recordings sounded good, but lacked that sense of depth and the sense of the space the recording was made in. Attack and dynamics were also muted, and the viscerality and extension of bass was noticeably (mostly) absent. From a resolution and detail perspective, things were not what I was (now) used to.

     

    Make no mistake, the stock DAVE was a life changing experience for me, and started me down this Reality Quest. Out of the box, it was the best I ever heard (by far) and still is, but very clearly the stock SMPS is significantly holding back the speed and dynamics and control that the DAVE is inherently capable of. Alas, once you hear what it is capable of, it is difficult to go back.

     

    So with the stock power and stock DAVE SMPS baseline established, time to swap in the Sean Jacobs DC3 (also plugged into the same generic wall outlet with the same generic power cord), and see what the DC3 brings to the party.

     

    After several days with the stock DAVE SMPS, the DC3 was a very welcome return to the characteristics I’ve learned to love of DAVE with an upgraded power supply: MUCH better/faster dynamics, significantly improved resolution and clarity and control, a viscerality and detail and presence in bass that is very engaging, lower stress and a more relaxed presentation, and an incredible sense of space.

     

    With the DC3, although volume remains the same, attack and grip on transients are just stronger and more dynamic. If you’ve had the experience of listening to a recording with poor dynamic range, then a recording with strong dynamic range, with the DC3 tracks sound like they are getting the qualitative equivalent of +4-5 dynamic range boost. Obviously the recordings themselves have not changed and the dynamic range is still the same, but the speed and control of the dynamics feel like they are much sharper and more controlled. Poor recordings become very good recordings, and good recordings become great recordings.

     

    Of particular note is the control in the bass range and the high treble. What was boomy and indistinct before becomes visceral and the detail in the bass becomes palpable. You can feel and hear the strings on the bass vibrate, and sense the resonances in the sound board, all with an incredible sense of effortless control. At the high end of the tonal range, recordings that were hot or border line harsh before now have a clarity and openness and naturalness that wasn’t there before. 

     

    The DC3 supply is simply able to drive and keep control of the output much better, while having much faster dynamics and more precise transients. In addition, all that wonderful sense of space and timing accuracy that DAVE is famous for gets taken to the next level with the DC3.

     

    Simply put, if you have a Chord DAVE, you haven’t heard what it is really capable of until you’ve heard it with an upgraded supply like the DC3 – a world class power supply reveals the DAVE for the world class DAC that it is.

     


    Sean Jacobs DC3 versus Sean Jacobs DC4


    When I first installed my DC3 several years ago, it was the most significant upgrade I had ever introduced to my system (even more impactful than adding mScaler to my DAVE). Prior to the DC3, I used to think that it was certain recordings that were holding back DAVE from what it was capable of. After hearing the DC3, I thankfully learned that it was the SMPS in DAVE that was holding back DAVE, and that better power revealed an amazing magic that had been waiting in the recordings all along. It was that experience that set me down the path of optimizing my digital server to maximize dynamics and transient performance and minimize noise (ending up with the Taiko Audio SGM Extreme), and now back to revisit power to my DAC.

     

    With the Sean Jacobs DC4 now fully broken in (those Mundorf caps take forever to settle in!), is there more magic in the DAVE that an upgraded power supply can reveal? Switching to the DC4 (also plugged into the same generic wall outlet with the same generic power cord), it was time to find out.

     

    Right out of the gate, it was obvious that DC4 was taking all the goodness of the DC3 and kicking up several notches: faster and more controlled dynamics (to put it mildly), breathtaking resolution and clarity and control, a true physicality and presence in the bass, and (most importantly for me) a remarkable holographic sense of space that spreads from behind the speakers to next to me on my sofa, and even above me. If DC3 makes instruments real and physically present, DC4 brings the performance into the room and up next to you, creating a hologram of the space of the performance that must be experienced to believe.

     

    I typically listen to small ensemble works, looking for that jazz club or coffee house live music experience. With the DC4, complex orchestral works are now a completely different experience. The sense of being in the hall (or at the conductor's podium, depending on the recording) is absolutely intoxicating. The resolution and dynamics almost allow you to pick out individual performers (like you can in a live performance)...so close but even this small taste gives a sense of intimacy and participation in the performance that is incredibly moving and intoxicating.

     

    With the DC4, this is a fundamentally different experience of music than I’ve enjoyed before, and hints that there may be even more that the Chord DAVE is capable of finding in these recordings. While I wait (and wait and wait and wait) patiently for my Paul Hynes custom three dual-regulated-rail SR7 to get to the front of Paul’s build queue, are there other things I can do to reveal all that DAVE is capable of doing? 

     

    Incredibly, yes there is. In Part 2 of this review, I will share my experiences with the Sound Application Power Grid Interface TT-7 power line conditioner.

     

     

    - Ray

     

     

     

     

    Part Two:

     

     

     



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    Excellent as always, Ray! A riveting read.

     

    I’ve long been an advocate of modularity in DACs, especially when it comes to power supplies. This is an emphatic case in point.

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    100% agreed Rajiv.  There are very practical constraints (BOM, room in case, etc) with any piece of equipment, which I appreciate and respect.  That being said, modularity (especially for modular components) enables customers to calibrate their investment to their own objectives/constraints. 

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    Ray, thanks for sharing your journey with everyone. This was so well written and insightful, that it was like reading a "who done it" thriller that is leaving me at the edge of my seat waiting for the next chapter. Well done!  All Digital

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    Great storytelling Ray, and great overall writing.  This part one was a quite a teaser, too.  BTW, what does Rob say (I love Rob too) when you explain to him the differences you hear with Sean's power supplies?  Also, what/where will the Hynes fit in this architecture?  Replace the DC4?

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    Although I had studied the pics before the conversion, it was still sobering to see the little CNC-ed chamber and aluminum billet walls created to isolate the stock PS. 
     

    I suspect just pulling the stock SMPS out of its coffin and putting it in an external box would improve sound, for those without a DC4 budget. I think that would be do-able.

     

    And great call-out on the connector. I used blue tape to index the orientation in case I lost my mind and my nerve reconnecting it!

     

    Great article, Ray. Mark

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    6 hours ago, ted_b said:

    Great storytelling Ray, and great overall writing.  This part one was a quite a teaser, too.  BTW, what does Rob say (I love Rob too) when you explain to him the differences you hear with Sean's power supplies?  Also, what/where will the Hynes fit in this architecture?  Replace the DC4?

     

    Ted, Rob is pretty clear that he thinks other power supplies are not only not helpful, but detrimental.  That being said, him voicing that opinion was (generally) a couple years ago, and there has been huge progress in upsampling (mScaler), digital servers, power, etc. since then.  Alas, with Covid restrictions, it is very difficult to be gathering in the same space to hear the same things.  Hopefully soon (and again, there is literally no one in digital audio I respect more than Rob Watts).

     

    I am continuing work to experiment with different power sources, build on the findings with the DC4.  A DR SR7 for the three rails may be a winner over the DC4, it may not (but it would be a replacement).  With Paul building custom SR7's again, hopefully there are some in the wild soon to test this (alas, my build is well down the queue)

     

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    4 hours ago, MarkusBarkus said:

    Although I had studied the pics before the conversion, it was still sobering to see the little CNC-ed chamber and aluminum billet walls created to isolate the stock PS. 
     

    I suspect just pulling the stock SMPS out of its coffin and putting it in an external box would improve sound, for those without a DC4 budget. I think that would be do-able.

     

    And great call-out on the connector. I used blue tape to index the orientation in case I lost my mind and my nerve reconnecting it!

     

    Great article, Ray. Mark

     

    Mark, FWIW, the DAVE SMPS vs DC3 test I wrote up in listening tests had the stock SMPS outside the DAVE case in a cardboard box ;)

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    Interesting read. Glad you liked the results...

     

    Just to state the obvious. I think it would be really nice to have a quick look at the noise level coming out of the DAVE with its stock SMPS vs. the others.

     

    The reason I bring this up is that in the past I have found at least one example where the power supply can clearly affect noise level and it was in fact a linear power supply that was problematic for the DAC. Sometimes the noise is ultrasonic so you won't necessarily hear the issue but nonetheless is being fed to the amp and speakers. Furthermore, you might find situations where as the power supply warms up, the noise will fluctuate over time.

     

    Considering the price of the DAVE, effort to open it up, warranty exceptions, etc... it would be nice to go that extra mile and ensure there are no issues with measurements.

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    Measurements would be very helpful Archimago.  I'm seeing different trends with 5V line vs ±15V lines, but I would love to map that to measurements to see what the correlations are.  Right now, I'm having to indirectly ascertain stuff, but I do feel like a naturalist in an EE world (as an EE, not an easy thing to say).  Subjectively, the impact is very clear, but objectively, why?  I'd love to know to more directly optimize the subjective outcomes.

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    11 minutes ago, Archimago said:

    Interesting read. Glad you liked the results...

     

    Just to state the obvious. I think it would be really nice to have a quick look at the noise level coming out of the DAVE with its stock SMPS vs. the others.

     

    The reason I bring this up is that in the past I have found at least one example where the power supply can clearly affect noise level and it was in fact a linear power supply that was problematic for the DAC. Sometimes the noise is ultrasonic so you won't necessarily hear the issue but nonetheless is being fed to the amp and speakers. Furthermore, you might find situations where as the power supply warms up, the noise will fluctuate over time.

     

    Considering the price of the DAVE, effort to open it up, warranty exceptions, etc... it would be nice to go that extra mile and ensure there are no issues with measurements.

    I wish all people who want measurements would say it this way. Bravo @Archimago . 

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    1 minute ago, The Computer Audiophile said:

    I wish all people who want measurements would say it this way. Bravo @Archimago . 

     

    I wish all of us that can't (currently) do measurements lived close enough to @Archimago so we could take our toys over and cross map measurements to subjective experience! (over an appropriate beverage (or three) of course)

     

     

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    1 hour ago, ray-dude said:

     

    I wish all of us that can't (currently) do measurements lived close enough to @Archimago so we could take our toys over and cross map measurements to subjective experience! (over an appropriate beverage (or three) of course)

     

     

    Totally! 
     

    It would be enjoyable and enlightening. 

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    4 hours ago, ray-dude said:

     

    I wish all of us that can't (currently) do measurements lived close enough to @Archimago so we could take our toys over and cross map measurements to subjective experience! (over an appropriate beverage (or three) of course)

     

     

     

    Absolutely. Wish you were closer! You've got some great gear there @ray-dude!

     

    The DAVE's output would be an interesting one to examine because of the very clean, strong "ideal" filter it implements. Changes to things like dynamic range, noise floor and variations in harmonic distortion could show quite clearly with a DAC like that. Would be a nice documentation of the effect that the power supply has.

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    1 minute ago, ecwl said:

    I have often wondered how much of the sonic improvement is due to a switch from SMPS to LPS thus reducing high impedance leakage current coming from the PC and how much of the sonic improvement is due to actual improvements to the power supply (noise in the DC current, impedance, etc.) Theoretically, one can test it out by feeding DAVE via Toslink using stock SMPS vs DC4 to compare.

    As someone who switched back to Toslink to avoid high impedance leakage current for DAVE, I have to admit it's a bit inconvenient.

    So at the end of the day, I think the system we want to have is the system we want to have. So if the DC4 upgrade is superior to the stock SMPS in @ray-dude's system sounds better, that's awesome. And it is great to be able to read about the experience and find out more about DC4. Very neat.

    Well said.

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    John Siau, who's the chief designer & CTO at Benchmark Media, said it best when, in an interview, stated that if you need a power conditioner for your system to sound its best, your equipment has really terrible power supplies in them.

     

    Here would be my thought: rather than waste money on a 3rd party power supply, buy a better DAC.

     

    From what I can tell, all of these products are garbage. 

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    1 minute ago, jeffhenning said:

    John Siau, who's the chief designer & CTO at Benchmark Media, said it best when, in an interview, stated that if you need a power conditioner for your system to sound its best, your equipment has really terrible power supplies in them.

     

    Here would be my thought: rather than waste money on a 3rd party power supply, buy a better DAC.

     

    From what I can tell, all of these products are garbage. 

    Wow. You’ve chosen to believe John as opposed to others. Can you say why you appeal to this authority?

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    52 minutes ago, PeterG said:

    Great piece!  Let's hope this evolves into a plug and play solution for those faint of heart

     

    Way back in the day, I got one the very first DC3's for DAVE. It was a very scary experience to crack the case and figure out stuff (and still is). I do know several people who've sent in their DAVE's to have the umbilical installed and their DAC tested with their supply, so there are options to make things more plug and play.

     

    That being said, the more DAC manufacturers move to separate modular power schemes, the easier it will be to have true plug and play. Separating out the power supply from the core DAC is inconvenient from a manufacturing and sales experience, but for folks that are buying/selling modular components (particularly at the high end) I think it very necessary and potentially very impactful on SQ.

     

    Modular isn't ideal for everyone though. There will always be a market for all in one type systems (streamer+DAC etc) where the convenience of one box will win out.

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    A great read, thank you... another good article for 2021 AStyle

    Never imagined i'd ever have a Dave and more than content to have a Qutest but i finally get to see a Pimp my ride version of 'Dave'.

    I am glad it worked so well and giving you pleasure Ray.

    Every bit of nice is need in these times..

    Really looking forward to part 2.0

    As so many questions with a TOTL upgrade now its  in the MOLA MOLA and Bartok territory.

    Already you can see the magnifying of every detail people want to see. Just in the above comments.

     Objective subjective... a literal power struggle of PSUs... 

    I cant wait. 

    Thank you ever so much for taking the time @ray-dude to document and post this artlcle.

     

    Happy 2021 to you and all.

     

    A non upgraded..

    Dave😁

     

    Another tick in the box for well regulated power...

     

     

     

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