[bikutoru]

...
Also, something to note: Even when you turn off the TT2 before swapping power, when the power cable is plugged in, the unit automatically powers on. It would be fine except there is a split second where the output stage gets current (you hear a thump on the speakers) and you see the volume LED come on during that time. I assume everyone else's TT2 does the same thing? And doesn't stay chilling in standby when power is plugged in?

Use stock power supply, have never experienced a thump on the speakers. Turn my TT2 on/off every day.

 

[absolutk]

Even when using the stock power supply, when you plug it in, the TT2 power on automatically. Not that you are doing this any more than once when plugging it in (or when you're A/B testing ), but still, would be nice to know what the design is.

Use stock power supply, have never experienced a thump on the speakers. Turn my TT2 on/off every day.

 

[RustyGates]

Even when using the stock power supply, when you plug it in, the TT2 power on automatically. Not that you are doing this any more than once when plugging it in (or when you're A/B testing ), but still, would be nice to know what the design is.

Yes, when you power the SMPS at the wall, the TT2 or M-Scaler will power up. The ON/OFF switch on the TT2 is what is intended for switching the TT2 on or off, but yes switching it at the wall will turn in on automatically. There is nothing wrong with this.

Secondly, the TT2 will spend some time instantiating the FPGA, starting up the output stage, doing circuit checks etc etc, when it is ready to output a signal, the output stage relays will click in and you will hear a very slight thump. Again, nothing wrong with this.

Your Farad Super3... tell me exactly how much the sound improved from the stock SMPS? Do you have a 15V as per the stock SMPS output?

This Supercap Linear PSU looks good with fantastic measurements, however you have to note the TT2's power supply is actually the Supercaps, inductors, filters and regulators INSIDE the TT2; the SMPS just converts AC and supplies DC (up to 4A @ 15V), and filters the switching noise. So having the Super3 in front of the TT2, is kinda just doubling up...

 

[absolutk]

Yes, when you power the SMPS at the wall, the TT2 or M-Scaler will power up. The ON/OFF switch on the TT2 is what is intended for switching the TT2 on or off, but yes switching it at the wall will turn in on automatically. There is nothing wrong with this.

Secondly, the TT2 will spend some time instantiating the FPGA, starting up the output stage, doing circuit checks etc etc, when it is ready to output a signal, the output stage relays will click in and you will hear a very slight thump. Again, nothing wrong with this.

Thank you for clarifying this! It is much appreciated. Yes, there are a series of checks and a relay click when it's ready to play.

Your Farad Super3... tell me exactly how much the sound improved from the stock SMPS? Do you have a 15V as per the stock SMPS output?

This Supercap Linear PSU looks good with fantastic measurements, however you have to note the TT2's power supply is actually the Supercaps, inductors, filters and regulators INSIDE the TT2; the SMPS just converts AC and supplies DC (up to 4A @ 15V), and filters the switching noise. So having the Super3 in front of the TT2, is kinda just doubling up...

Yes, it is a 15V supply, absolutely. And yes, you are absolutely correct - as Rob Watts' also cites - that the power supply is the network of supercaps, inductors, filters and regulators *inside* the TT2. But what I'm hearing is not subtle and wish I could share that in a way that was objective. Perhaps I'll pick up a good microphone and setup a recording this coming weekend. As I summarized in the previous post, there is an abundance of detail that emerges with the Super3, which results in better spatial placement and transients. I'm actually now curious to stack this up against a DAVE, which has an in-built AC/DC power source (likely switch mode).

It is possible that the SMPS is providing 15v with switching noise on the +ve or gnd lines, which the on-board PSU is unable to fully clean. Or perhaps that the AC>SMPS cable isn't robust enough or that the SMPS>TT2 cable is too long, picking up RF on the way or causing an I*R sag when the unit is demanding.

As I'd mentioned, nothing would have made me happier than to prove Rob/Chord right and report that the SMPS is very close/better than an aftermarket voltage source. Mattijs is great to work with, and I'm sure he'd oblige a return on the Farad. But alas, there are noticeable gains to be had. For that (and for this community <3), I'm happy to be a guinea pig on how the unit fares long term in this configuration (and what it will cost me to service if/when it goes out ).

 

[RustyGates]

Thank you for clarifying this! It is much appreciated. Yes, there are a series of checks and a relay click when it's ready to play.



Yes, it is a 15V supply, absolutely. And yes, you are absolutely correct - as Rob Watts' also cites - that the power supply is the network of supercaps, inductors, filters and regulators *inside* the TT2. But what I'm hearing is not subtle and wish I could share that in a way that was objective. Perhaps I'll pick up a good microphone and setup a recording this coming weekend. As I summarized in the previous post, there is an abundance of detail that emerges with the Super3, which results in better spatial placement and transients. I'm actually now curious to stack this up against a DAVE, which has an in-built AC/DC power source (likely switch mode).

It is possible that the SMPS is providing 15v with switching noise on the +ve or gnd lines, which the on-board PSU is unable to fully clean. Or perhaps that the AC>SMPS cable isn't robust enough or that the SMPS>TT2 cable is too long, picking up RF on the way or causing an I*R sag when the unit is demanding.

As I'd mentioned, nothing would have made me happier than to prove Rob/Chord right and report that the SMPS is very close/better than an aftermarket voltage source. Mattijs is great to work with, and I'm sure he'd oblige a return on the Farad. But alas, there are noticeable gains to be had. For that (and for this community <3), I'm happy to be a guinea pig on how the unit fares long term in this configuration (and what it will cost me to service if/when it goes out ).

Yes DAVE has an internal SMPS. Switch mode power supplies are Chords philosophy, even their power amps like the Ultima are all switching PSU's.

Okay. Very tempting now. You mention a upgrade in SQ when powering the M-Scaler off the Super3? I fail to see how this would work, being an all digital device.

As far as I can think, as long as the analogue stage in a DAC is protected from RF (plenty of which is generated by the FPGAs, but analogue stage well protected), and there is no input jitter...all of which we can tell there is none of from the stellar measurements of the TT2, then how would a cleaner PSU to M-Scaler help?

 

[Triode User]

Yes DAVE has an internal SMPS. Switch mode power supplies are Chords philosophy, even their power amps like the Ultima are all switching PSU's.

Okay. Very tempting now. You mention a upgrade in SQ when powering the M-Scaler off the Super3? I fail to see how this would work, being an all digital device.

As far as I can think, as long as the analogue stage in a DAC is protected from RF (plenty of which is generated by the FPGAs, but analogue stage well protected), and there is no input jitter...all of which we can tell there is none of from the stellar measurements of the TT2, then how would a cleaner PSU to M-Scaler help?

Well, all I can say is that in my experience it does help to power HMS using a good quality LPS or indeed a battery. The latter is explained because it cuts out the ground plane route for noise to get to the DAC.

I have been trying various LPSs over the last few weeks and there are significant differences in sound quality to my ears between the ones that I tried. I have settled on a Sean Jacobs DC3 supply for my HMS (but I have yet to try his DC4 power supply with HMS and that may well dislodge the DC3!). As with many things to do with digital audio, it is all about noise. It is a big leap of faith for you to say that the analogue stage in the DAC is protected from noise (I have also been doing the same experiments with other DACs, not just Chord, and all so far benefit from cleaner supplies even including the Dave).

A word of caution though to anyone wanting to experiment. Any change of power supply away from the one supplied by the (any) manufacturer may lead to warranties being voided. Also, not all third party supplies accurately state their output voltages so what is stated as 15v may turn out to be well over 16v. So be aware of the risk when you try something and proceed with caution.

 

[ZappaMan]

tidal is only $4 for 4 months (120 days) - get it while you can as they shut these offers down quickly too:

https://www.whathifi.com/au/news/ge...-dollar4-with-this-streaming-deal-of-the-year

 

[absolutk]

Yes DAVE has an internal SMPS. Switch mode power supplies are Chords philosophy, even their power amps like the Ultima are all switching PSU's.

Yes. Modern SMPS have eliminated two issues that used to plague the class before: 1) resonant SMPS designs can deliver huge bursts of current instantaneously (which Class A/B amplifiers demand) and 2) they employ extremely high switching frequencies (>1 MHz), which should not have audible artifacts. In amplification, these have shown huge benefits. In fact my Micromega M150 also had an SMPS (as did the Devialets I had). But their PSUs were built into their PCBs so one could not swap them out to check for audible differences. We're also now looking at sampling rates of 768 KHz which is approaching the high switching frequencies.

Okay. Very tempting now. You mention a upgrade in SQ when powering the M-Scaler off the Super3? I fail to see how this would work, being an all digital device.

Truth be told, I haven't done much A/B with the M Scaler because I heard immediate benefits the first time I powered it with the Farad, and others have also described benefits powering the HMS with battery and other linear supplies. @Triode User calls out some more observations above. I will gather some more observations this weekend.

As far as I can think, as long as the analogue stage in a DAC is protected from RF (plenty of which is generated by the FPGAs, but analogue stage well protected), and there is no input jitter...all of which we can tell there is none of from the stellar measurements of the TT2, then how would a cleaner PSU to M-Scaler help?

That's the curious part - LPS or SMPS, both the TT2 and HMS will produce RF from the FPGAs. So there is some combination of a) the audible differences are not RF related, b) there is elimination of power-source related RF, c) quieter power sources reduce the FPGA's generated RF.

Without a test bench, it is hard for me to measure any of this and provide objective proof. Till then, all we have are community-provided data points!

 

[absolutk]

A word of caution though to anyone wanting to experiment. Any change of power supply away from the one supplied by the (any) manufacturer may lead to warranties being voided. Also, not all third party supplies accurately state their output voltages so what is stated as 15v may turn out to be well over 16v. So be aware of the risk when you try something and proceed with caution.

Here are measured outputs from the SMPS and the Farad Super3. You can see I caught the Fluke measuring the SMPS between the 15.12v, 15.13v and 15.14v it was constantly fluttering between. In contrast, the Farad was solidly planted at 14.96v, so no worries with over-voltage here. And based on other posts here, we know running it at a lower voltage (like 12v of the PowerAdd) is OK.

 

[Ragnar-BY]

how would a cleaner PSU to M-Scaler help?

I don't know how exactly it works, but it works. All three components of my system are powered with Farads. SQ difference is pretty big.
.

 

[Triode User]

That's the curious part - LPS or SMPS, both the TT2 and HMS will produce RF from the FPGAs. So there is some combination of a) the audible differences are not RF related, b) there is elimination of power-source related RF, c) quieter power sources reduce the FPGA's generated RF.

To be clear, the DACs I have experimented with are from many of the mainstream manufacturers and in my opinion this is not a Chord thing as such.

 

[RustyGates]

Well, all I can say is that in my experience it does help to power HMS using a good quality LPS or indeed a battery. The latter is explained because it cuts out the ground plane route for noise to get to the DAC.

I have been trying various LPSs over the last few weeks and there are significant differences in sound quality to my ears between the ones that I tried. I have settled on a Sean Jacobs DC3 supply for my HMS (but I have yet to try his DC4 power supply with HMS and that may well dislodge the DC3!). As with many things to do with digital audio, it is all about noise. It is a big leap of faith for you to say that the analogue stage in the DAC is protected from noise (I have also been doing the same experiments with other DACs, not just Chord, and all so far benefit from cleaner supplies even including the Dave).

A word of caution though to anyone wanting to experiment. Any change of power supply away from the one supplied by the (any) manufacturer may lead to warranties being voided. Also, not all third party supplies accurately state their output voltages so what is stated as 15v may turn out to be well over 16v. So be aware of the risk when you try something and proceed with caution.

The ground planes of both the M-scaler and TT2 are coupled via the BNC grounds. That's the reason why it is important to have special Ferrite choked cables on both the output of the M-Scaler and prior to the input of the TT2 which filter out RF noise propagated via the BNC. As long as the ferrited cable is designed correctly, RF noise propagation into the DAC will be minimized, while the inductance of the ferrites (given correct sizing & tolerances) won't start to round off the rising and falling edges of the digital signal, given its high spectrum bandwidth. How the analogue stage within the TT2 is protected from the TT'2 FPGA is all Robs magic.

As for ground plane coupling via power... the ground planes are floating relative to earth. There is no earth on TT2 or M-Scaler. The SMPS has very small leakage currents back to GND.

This makes me wonder though, where does all that RF energy go? Dissipated as heat around the chassis? Maybe coupling the ground plane to drain to earth via the Super3 helps in some way...? Need to find a way to get a unit loaned out...

Rob, re. SMPS's:
"No it's not a fairly standard unit - I went through a lot of units before approving this one. It measures extremely well - giving the same measurements connected and disconnected (measuring wideband). Also, SQ wise, disconnecting the unit makes no difference (TT will run for 10 seconds with no power). A linear PSU will almost certainly make it sound worse, as the audiophile ones have no RF filtering, unlike the supplied PSU. Moreover, linear supplies create much more magnetic noise, measurable audio BW noise, worse leakage currents (interwinding capacitance is much larger on a toroidal transformer) and are transparent to mains bourne RF noise. And they are horribly inefficient, and this can in itself degrade SQ. So absolutely not recommended. "

" No a linear supply at best will sound the same, at worst a brighter and harder sound and less musical. TT2 PSU is not the brick that comes with it, it's the arrangement of filters and supercaps built into the unit. The supercap/large input inductor means the PSU brick only supplies DC current. Moreover, the PSU brick has been very carefully selected for extremely low leakage currents into ground; replacing it with a battery produces no change at all in measured performance using a 96 kHz bandwidth. A linear PSU will add comparatively large levels of hum and RF noise, with orders of magnitude higher coupling capacitance to the mains. "

I'm pulling out my hair. Conflicting reports. But the Super3 measures so well over a 100 KHz bandwidth (we are talking max noise -122dBV @ 55KHz), I might have to take Robs words with a grain of salt, for the first time ever.

 

[Rob Watts]

The ground planes of both the M-scaler and TT2 are coupled via the BNC grounds. That's the reason why it is important to have special Ferrite choked cables on both the output of the M-Scaler and prior to the input of the TT2 which filter out RF noise propagated via the BNC. As long as the ferrited cable is designed correctly, RF noise propagation into the DAC will be minimized, while the inductance of the ferrites (given correct sizing & tolerances) won't start to round off the rising and falling edges of the digital signal, given its high spectrum bandwidth. How the analogue stage within the TT2 is protected from the TT'2 FPGA is all Robs magic.

As for ground plane coupling via power... the ground planes are floating relative to earth. There is no earth on TT2 or M-Scaler. The SMPS has very small leakage currents back to GND.

This makes me wonder though, where does all that RF energy go? Dissipated as heat around the chassis? Maybe coupling the ground plane to drain to earth via the Super3 helps in some way...? Need to find a way to get a unit loaned out...

Rob, re. SMPS's:
"No it's not a fairly standard unit - I went through a lot of units before approving this one. It measures extremely well - giving the same measurements connected and disconnected (measuring wideband). Also, SQ wise, disconnecting the unit makes no difference (TT will run for 10 seconds with no power). A linear PSU will almost certainly make it sound worse, as the audiophile ones have no RF filtering, unlike the supplied PSU. Moreover, linear supplies create much more magnetic noise, measurable audio BW noise, worse leakage currents (interwinding capacitance is much larger on a toroidal transformer) and are transparent to mains bourne RF noise. And they are horribly inefficient, and this can in itself degrade SQ. So absolutely not recommended. "

" No a linear supply at best will sound the same, at worst a brighter and harder sound and less musical. TT2 PSU is not the brick that comes with it, it's the arrangement of filters and supercaps built into the unit. The supercap/large input inductor means the PSU brick only supplies DC current. Moreover, the PSU brick has been very carefully selected for extremely low leakage currents into ground; replacing it with a battery produces no change at all in measured performance using a 96 kHz bandwidth. A linear PSU will add comparatively large levels of hum and RF noise, with orders of magnitude higher coupling capacitance to the mains. "

I'm pulling out my hair. Conflicting reports. But the Super3 measures so well over a 100 KHz bandwidth (we are talking max noise -122dBV @ 55KHz), I might have to take Robs words with a grain of salt, for the first time ever.

Oh dear.

PSU noise at 55kHz is a completely meaningless specification for the M scaler. You could put HUGE levels of noise at this frequency and it will have NO effect whatsoever at the DAC side, due to the multistage regulation and filtering plus the OP galvanic isolation within the M scaler.

You have missed the most important point - capacitive coupling, and it's capacitive coupling that makes all the difference.

The M scaler has galvanic isolation on its OP but it has capacitive coupling of 2pF across the isolated domains. At 2GHz that is an impedance of 40 ohms; which means the isolation is not very effective, and there exists a path for current to potentially flow. And it's the current flowing into the DACs ground plane that is so important, as a current flow into the DAC ground-plane will create more noise floor modulation (brighter sound fooling people into thinking it is more transparent) and more correlated small signal errors (poorer perception of depth - giving the illusion of a wider and "better" soundstage).

I have spent many man months over several years researching this issue, and I fully understand the situation and how to take steps to ameliorate it; given the fixed and inescapable domain coupling capacitance, the problem is reduced via RF filters, which have course been embedded within the M scaler - to lengths that you wouldn't believe (even logic to logic coupling is treated). I spent a lot of time running SPICE simulations to improve the isolation - and this can be done via RF filters which constrains the current path within the local domain, thus breaking the current flowing into the DAC. But this approach is dependent upon parasitic capacitances which then dominate the effectiveness of this approach.

Given that I have done everything that is possible within the M scaler, how can the PSU help? Remember that the issue is current flow, and this only depends upon the loop impedance: mains>PSU>M scaler>Galvanic isolation on M scaler>BNC cables>DAC ground plane>DAC PSU>mains. You only need one of those steps to have high impedance at 2GHz and you are done; no current will flow and you will get no loss in SQ at all. And for readers that have not followed my previous posts it is the 2GHz range where we have the problem.

So how can we improve it with the PSU? You must use RF filters on the input side and the output side; RF filters reduces the coupling currents and helps; you should use a non grounded PSU - then the coupling is via neutral on the mains not earth - and to reduce coupling via the neutral you need a low inter-winding capacitance without using a grounded screen as this will increase the coupling capacitance. You get all these things with the supplied PSU - it has RF filter on the input and output, being a SMPS it uses a small transformer with low coupling capacitance and it is not grounded.

When you connect an "audiophile" linear PSU you will destroy all of these benefits - no RF filters at all, big screened toroidal transformers with huge capacitive inter-winding capacitance; so you will degrade the isolation at 2GHz, and increase the coupling currents into the DAC. You then get rewarded with a brighter SQ (conning you into thinking it's more transparent), a wider soundstage, an artificial etched quality and of course more listening fatigue - all due to more noise floor modulation and increased small signal amplitude errors.

Sorry if I am being a bit hard on you, but I do get very frustrated when I see audiophiles spend cash on "upgrades" that I know are damaging sound quality and more importantly the ability to enjoy music.

Keep safe and happy listening in these troubled times.

 

[Whazzzup]

If you can’t plug the thing in and enjoy it what’s the point?

 

[RustyGates]

Oh dear.

PSU noise at 55kHz is a completely meaningless specification for the M scaler. You could put HUGE levels of noise at this frequency and it will have NO effect whatsoever at the DAC side, due to the multistage regulation and filtering plus the OP galvanic isolation within the M scaler.

You have missed the most important point - capacitive coupling, and it's capacitive coupling that makes all the difference.

The M scaler has galvanic isolation on its OP but it has capacitive coupling of 2pF across the isolated domains. At 2GHz that is an impedance of 40 ohms; which means the isolation is not very effective, and there exists a path for current to potentially flow. And it's the current flowing into the DACs ground plane that is so important, as a current flow into the DAC ground-plane will create more noise floor modulation (brighter sound fooling people into thinking it is more transparent) and more correlated small signal errors (poorer perception of depth - giving the illusion of a wider and "better" soundstage).

I have spent many man months over several years researching this issue, and I fully understand the situation and how to take steps to ameliorate it; given the fixed and inescapable domain coupling capacitance, the problem is reduced via RF filters, which have course been embedded within the M scaler - to lengths that you wouldn't believe (even logic to logic coupling is treated). I spent a lot of time running SPICE simulations to improve the isolation - and this can be done via RF filters which constrains the current path within the local domain, thus breaking the current flowing into the DAC. But this approach is dependent upon parasitic capacitances which then dominate the effectiveness of this approach.

Given that I have done everything that is possible within the M scaler, how can the PSU help? Remember that the issue is current flow, and this only depends upon the loop impedance: mains>PSU>M scaler>Galvanic isolation on M scaler>BNC cables>DAC ground plane>DAC PSU>mains. You only need one of those steps to have high impedance at 2GHz and you are done; no current will flow and you will get no loss in SQ at all. And for readers that have not followed my previous posts it is the 2GHz range where we have the problem.

So how can we improve it with the PSU? You must use RF filters on the input side and the output side; RF filters reduces the coupling currents and helps; you should use a non grounded PSU - then the coupling is via neutral on the mains not earth - and to reduce coupling via the neutral you need a low inter-winding capacitance without using a grounded screen as this will increase the coupling capacitance. You get all these things with the supplied PSU - it has RF filter on the input and output, being a SMPS it uses a small transformer with low coupling capacitance and it is not grounded.

When you connect an "audiophile" linear PSU you will destroy all of these benefits - no RF filters at all, big screened toroidal transformers with huge capacitive inter-winding capacitance; so you will degrade the isolation at 2GHz, and increase the coupling currents into the DAC. You then get rewarded with a brighter SQ (conning you into thinking it's more transparent), a wider soundstage, an artificial etched quality and of course more listening fatigue - all due to more noise floor modulation and increased small signal amplitude errors.

Sorry if I am being a bit hard on you, but I do get very frustrated when I see audiophiles spend cash on "upgrades" that I know are damaging sound quality and more importantly the ability to enjoy music.

Keep safe and happy listening in these troubled times.

@Rob Watts Not hard on me at all, this is the answer I want to hear! Designers stepping up and provide the OQE and/or justification to their design decisions! These many days at home with my system is making the "WHAT IF" rattle through my brain. But you've got the many years, decades of investigating all the what if's, so I appreciate your answer .

Just to clarify - you mention to reduce coupling currents, one of the decisions is to preclude an earth for these systems and couple via AC neutral. DAVE has an earth, as well as many of the Chord amps, from low to high end. What benefit comes from choosing an SMPS with no earth for the TT2 & M-Scaler?