[Harveysouth]

2 GHz Noise

Before I added the RF isolation treatment on the M scaler outputs, HF GHz clip on ferrites sounded considerably better - warmer sound quality, with better depth and focus. I understand why it works as the problem is down to RF currents (peak problem area is around 2 GHz) flowing in a loop from the mains>Hugo M scaler FPGA ground>galvanic isolated OP>BNC cable> DAC ground plane> back to the mains. It's when the current flowing through the DAC ground plane is where the SQ problems are happening. If we can reduce the value of the currents by increasing the loop impedance then we get less voltage drops across the DAC ground plane and then less correlated noise and lower noise floor modulation. The lower noise floor modulation improves warmth; the reduction in correlated noise (that's noise/distortion that is in the audio bandwidth and is linked to the actual signal) degrades small signal amplitude accuracy, and that degrades the perception of depth.

It's all very straightforward and well understood - double the loop impedance at 2GHz and currents will half, and we get a corresponding improvement in sound quality - better depth and a warmer sound.

It doesn't matter too where you increase the loop impedance either; you can do it at the BNC output drivers, or through the cable, or via the PSU on the M scaler, or via the PSU on the DAC - it's the total loop impedance that counts. If the loop impedance is infinite, no current can flow, audio nirvana results. Problem is, at 2GHz even 2pF of capacitance (which is a very small capacitance) is very significant - it is 40 ohms, so will allow current to flow. Moreover, the ear/brain is ultra sensitive to this problem, so the faintest trace of an error is audible.

So why did adding ferrites improve the SQ? Ferrites work by increasing the common mode impedance, but keeping the differential impedance the same. The wanted signal is differential, the unwanted current is common mode; so adding ferrites increases the loop impedance, without affecting the wanted signal; if you double the number of ferrites, you half the loop currents, thus halving the SQ problem.

The treatments I put into the M scaler was extensive and aimed at increasing the loop impedance, by improving the galvanic isolation, improving the drivers and the driver PSU, and adding RF filters and chip ferrites into the BNC output ground. In terms of sound quality, I gained about an order of magnitude improvement in SQ - it went from a big problem to a small one. When I then added clip on ferrites it sounded worse - and I was not expecting that. I am not sure of the reason exactly - I suspect a resonance between the internal M scaler ferrites and the clip on ferrites air gap, making the loop impedance lower overall. But solid core ferrites do still improve the SQ - but I should add that it's not a huge difference. When I travel, I don't bother, as it's simply too small a difference and I stick to stock. Compared to the SQ that the M scaler adds, we are talking about the surface finish of the icing on top of the cake - it's the iced cake that's important.

But remember it's the overall loop impedance that's important, and the PSUs come into this too. If you replace the supplied PSU with linears, apart from breaking the warranty, will degrade the sound quality. This is because linear PSUs have no RF filters - the supplied one comes with input and output RF filters. Also the supplied one has been very carefully selected for no grounding, and very low inter-winding capacitance - many times smaller than toroidal transformers. The lower inter-winding capacitance, together with the RF filters, increase the loop impedance and improve the sound quality. By using a linear will increase noise floor modulation (making it sound brighter, fooling the audiophile into thinking it's more transparent) and increase correlated noise thereby degrading depth (and then the hapless audiophile will then convince themselves into thinking it's better because perceived width is artificially wider due to the poorer depth). Confirmation bias and placebo is a very real problem with listening tests!

But if you want to almost completely isolate the M scaler from the DAC then use a battery power bank (so long as you site it correctly) - then the loop impedance becomes very high, and then the BNC cables no longer have an impact on SQ as no current can now flow as there is no longer a loop. Is this something I do in practice - no - the difference isn't large enough to bother with charging batteries. At the end of the day I just want to simply enjoy my music more, and I don't need to go to silly lengths to do that.

I have used a reply to a post by Rob Watts from November 2019 to explain that the information about the 2 GHz noise originally came from the designer of the DAVE / M-Scaler. The post clearly states that the peak problem area for the noise is at 2 GHz.

This noise is at a low level and escapes the internal counter-measures in the M-Scaler that successfully block noise at lower frequencies. It is the presence of this noise on the shield of the coax cable, not on the central conductor, that is the point of concern. The screen is connected to ground at both the M-Scaler and DAVE ends. The grounds of the M-Scaler and DAVE are also joined through the mains Earth wiring. There is therefore a loop in which this radio frequency noise voltage can cause current to flow. This is, I believe, a well established, textbook mechanism for noise transmission in coax cables

As I understand it, Rob believes that noise floor modulation in the DAVE caused by this ground - born noise is responsible for a small degradation in sound quality, because it impinges upon The D to A conversion process.

For the home user of DAVE / M-Scaler there are a number of possible responses to learning of all this, including:

1. Making no changes to one's audio system around the DAVE / M-Scaler. They are great sounding components anyway. This is what I did for over 3 years. I just made sure I was using cables professionally constructed of well-screened 75 ohm coax cables terminated with 75 ohm characteristic impedance BNC connectors to link the two devices.

2. Breaking the ground loop by running the M-Scaler from a battery or Power-bank to gain a small uplift in sound quality. This approach requires one to make provision for either manually or automatically charging the battery in the listening room.

3. Breaking the ground loop by using twin optical links, between the M-Scaler and DAVE. This involves adding active circuitry between the components and in one becoming an early - adopter of technology (384KHz optical transmission of digital audio signals) that is not standard in domestic audio equipment.

4. Adding ferrite cable cores to the coax cables to increase the impedance of the shield. This has the disadvantage of not fully breaking the ground loop. It does, however attenuate the ground currents. If these can be sufficiently attenuated, one hopes that they will fall below a threshold value at which no further improvement in sound quality can be heard.

I admire the ingenuity of those who have implemented methods 2 and 3. They should be getting the full uplift in sound quality that is possible. Personally, I have not been inclined to go down these routes.

In the end, I succumbed to curiosity and tried method 4, adding ferrite cable cores, as outlined in my earlier post. It does unfortunately require one to make one's own cables in order to get the ferrites in position between the BNC connectors. This method only uses passive means to attenuate the noise, and there is no added circuitry or equipment in the listening room. The new cables just disappear back in behind the audio rack and one is left to relax and enjoy listening to music.

 

[Jawed]

In the end, I succumbed to curiosity and tried method 4, adding ferrite cable cores, as outlined in my earlier post.

I fully agree with your motivations I've been ferriting since 2017...

I just think that the graphs I've presented show that the problem lies at other frequencies. Rob's description of problems at 2GHz are related to "Before I added the RF isolation treatment on the M scaler outputs [...]". I believe this is why the graphs show the best result at 2GHz as that's where Rob focussed his efforts.

When you add ferrites whose resonances are centred upon the 2GHz region, they will inevitably affect lower and higher frequencies. I suspect the benefit you're hearing is primarily due to reduced noise at frequencies below 2GHz.

I highly recommend you also put ferrites on the full length of all power cables in your system.: the mains cable on DAVE and both of the cables for the SMPS for HMS.

 

[skyelistener]

I’m using an Aries G2 to my HMS with a Curious USB (enhanced) cable.

Just wondering if anyone has experience of using optical or co-ax connection to improve the sound in similar setups?

 

[ardbeg1975]

I’m using an Aries G2 to my HMS with a Curious USB (enhanced) cable.

Just wondering if anyone has experience of using optical or co-ax connection to improve the sound in similar setups?

Not exactly the same but I’ve run USB and coaxial into HMS from a Zen Stream and a Lumin U2 Mini and in both cases I preferred coaxial. Subtle difference and possibly placebo but to me there was something more engaging in downstream output.

 

[happybunny12]

One sonic dividend after a total loss of power for 5 days in the big storms of 2021--------much improved musical pleasure!!
I bought an ANKER 757 power bank to help out if faced with a similar situation in the future[so far no repeat of blackouts]
It sat for a good while doing nothing till i read in this forum about battery power for the Hugo TT2 and M scaler.
What a wonderful improvement after i connected the standard power supplies to the AC outlets-----easiest analogy would be as if switching on a light in a rather dimly lit room.
Together they draw 32-33 watts so a single charge will last 22 'ish hours.
Big ta to all those recommending battery power !!

 

[Widell]

One sonic dividend after a total loss of power for 5 days in the big storms of 2021--------much improved musical pleasure!!
I bought an ANKER 757 power bank to help out if faced with a similar situation in the future[so far no repeat of blackouts]
It sat for a good while doing nothing till i read in this forum about battery power for the Hugo TT2 and M scaler.
What a wonderful improvement after i connected the standard power supplies to the AC outlets-----easiest analogy would be as if switching on a light in a rather dimly lit room.
Together they draw 32-33 watts so a single charge will last 22 'ish hours.
Big ta to all those recommending battery power !!

So you saying I can get off the grid with my G1, TT2/HMS? then how so? ready to go all in ( into the woods, add solar panels)

 

[vrockz]

Hi,

I need some help related to the USB cable that I am planning to buy to connect my source to M Scaler.

I am planning to use my android tablet Lenovo Yoga Tab 11 (https://www.bestbuy.com/site/lenovo-yoga-tab-11-11-tablet-256gb-storm-gray/6472587.p?skuId=6472587) with USB C port to connect to my Chord Hugo M Scaler. I will be playing the music using USB Audio Player PRO app on the android tablet.

Should I buy a "UCB C to UCB B" cable or "UCB C to UCB B OTG" cable?

Thanks in advance.

Update: To anyone who might have similar question, I ordered "UCB C to UCB B OTG" from moon audio and it works flawlessly in my system.

 

[ZappaMan]

Hi,

I need some help related to the USB cable that I am planning to buy to connect my source to M Scaler.

I am planning to use my android tablet Lenovo Yoga Tab 11 (https://www.bestbuy.com/site/lenovo-yoga-tab-11-11-tablet-256gb-storm-gray/6472587.p?skuId=6472587) with USB C port to connect to my Chord Hugo M Scaler. I will be playing the music using USB Audio Player PRO app on the android tablet.

Should I buy a "UCB C to UCB B" cable or "UCB C to UCB B OTG" cable?

Thanks in advance.

Deleted

 

[Akari Light]

On February 10, 2023, an interview with John Franks, CEO of Chord Electronics, appeared on Phil web, a Japanese audio information website.
There he says the following I would like to share with you all this delightful information that has been lifted.
This is a more specific announcement from the CEO about a product that was called X Scaler or Choral range scaler.
I look forward to Rob Watts' comments on what information is available to us at this time.

--------------------------------------------------------------------------------------------------------------------------------------------------------------------------
John Franks: I firmly believe that DAVE is still the best performing DAC in the world. But digital consultant Rob Watts is thinking even further ahead: during the isolation period of COVID-19, he was busy designing in his home lab.

It is the "Super Scaler". This is a product of the same CHORAL range as DAVE. We had considered the name "DAVE Scaler," but after much discussion, we settled on "Super Scaler". It's like the Hugo M Scaler. We are also considering a separate power supply. The whole system will be huge, with three enclosures, but it will be a quantum leap in DAVE technology.

---That's very exciting! When will it be available?

John Franks: We're preparing a lot of things, but we'll probably have something to show you by during this year.

https://www.phileweb.com/interview/article/202302/10/916.html

 

[ecwl]

It is the "Super Scaler". This is a product of the same CHORAL range as DAVE. We had considered the name "DAVE Scaler," but after much discussion, we settled on "Super Scaler". It's like the Hugo M Scaler. We are also considering a separate power supply. The whole system will be huge, with three enclosures, but it will be a quantum leap in DAVE technology.

Oh no. I don’t think I have shelf space for so many boxes. Does this mean the Super Scaler would be in 3 enclosures? Or does it mean Super Scaler would be in 2 enclosures and then you have DAVE so 3 boxes? Unlike some people here who wants separate power supply, I’m perfectly happy with how everything is setup right now. I guess I can leave the power supply outside of my cabinet on the floor or something. Haha… Maybe John Franks count the M-Scaler switching power supply as a separate enclosure too. Anyway, thanks for posting the link.

 

[Akari Light]

Oh no. I don’t think I have shelf space for so many boxes. Does this mean the Super Scaler would be in 3 enclosures? Or does it mean Super Scaler would be in 2 enclosures and then you have DAVE so 3 boxes? Unlike some people here who wants separate power supply, I’m perfectly happy with how everything is setup right now. I guess I can leave the power supply outside of my cabinet on the floor or something. Haha… Maybe John Franks count the M-Scaler switching power supply as a separate enclosure too. Anyway, thanks for posting the link.

Thanks for the reply, ecwl. I am guessing that the three enclosures are 1. DAVE 2. Super Scaler 3. separate power supply for Super Scaler. But for now, let's wait for Rob Watts' comments.

I am a M/DAVE user. I have learned a lot from this forum and thank you all.

 

[GuiltyRocker]

On February 10, 2023, an interview with John Franks, CEO of Chord Electronics, appeared on Phil web, a Japanese audio information website.
There he says the following I would like to share with you all this delightful information that has been lifted.
This is a more specific announcement from the CEO about a product that was called X Scaler or Choral range scaler.
I look forward to Rob Watts' comments on what information is available to us at this time.

--------------------------------------------------------------------------------------------------------------------------------------------------------------------------
John Franks: I firmly believe that DAVE is still the best performing DAC in the world. But digital consultant Rob Watts is thinking even further ahead: during the isolation period of COVID-19, he was busy designing in his home lab.

It is the "Super Scaler". This is a product of the same CHORAL range as DAVE. We had considered the name "DAVE Scaler," but after much discussion, we settled on "Super Scaler". It's like the Hugo M Scaler. We are also considering a separate power supply. The whole system will be huge, with three enclosures, but it will be a quantum leap in DAVE technology.

---That's very exciting! When will it be available?

John Franks: We're preparing a lot of things, but we'll probably have something to show you by during this year.

https://www.phileweb.com/interview/article/202302/10/916.html

Well this is interesting, thanks for sharing.

 

[jacc]

Separate power supply? Then it couldn’t be a medical grade switcher anymore

 

[ecwl]

Separate power supply? Then it couldn’t be a medical grade switcher anymore

On the other hand, I don’t think Chord has a product that doesn’t use switching power supply. So I’d be surprised if they start making linear power supplies just for Super Scaler.

What is much more likely is that the Choral form factor would limit the amount of room to put everything from super switching power supply RF filtering to ground loop noise rejection to new FPGA designs into a single chassis so it would be easier to just use two Choral chassis. Except if that were the case, I wish they would just switch to the Ultima series chassis for a single box then.

It’s always fun to second guess what’s coming next but I’ve learnt through my years with Chord products that the products will be ready when they are ready and they’ll be great.

 

[Super Pang]

We are also considering a separate power supply.

My thoughts are with Sean Jacobs at this difficult time.