My dedicated audio room build - QuadDiffusor's Big Dig

[QuadDiffuser]

Good news on the sourcing of my in-wall AC cables!
Keystone Cable will manufacture customized AC cables for my needs, sold in 100m spools, for just a few USDs per meter, having:

1) copper conductor insulation: XLPE (superior dielectric and durability, compared to PVC)
2) multi-stranded copper conductor bundle's gauge/thickness: 6mm2 (9AWG equiv.), and 10mm2 (7AWG equiv.)
3) multi-stranded copper conductor bundle's XLPE insulation color: brown (live) and blue (neutral), dyed to color code
4) twist frequency: exceeding 7 full rotations per meter (more consistently and tightly wound than possible using human hands)
5) sheathing - none (taped) for the 6mm2, and XLPE for the 10mm2; both will prevent unravelling of twisted conductors within
6) sheathing color: milky but transparent (polarity of the conductors will be visible - brown and blue)
7) sheathing thickness: very thin, for maximum flexibility and low-friction installation
8) sheathing will not be perfectly round, but instead conform to the bumpy contours of the twisted conductors within

As the costs are so nominal, I'll likely install both gauges of AC cables through the same PVC conduit (running between the MCB box and the AC duplexes) and determine which sounds "better" later, through experimentation.

The ground conductor will likely be a single multi-stranded copper conductor bundle of 10mm2 w/ XLPE insulation, loosely pulled through the PVC conduit, cut to the same length for all eight AC duplexes distributed throughout the component "end" of the listening room and anchored in a "star" configuration at the dedicated audio MCB, to ensure that there is no impedance delta between the ground wires.

 

[QuadDiffuser]

This old drawing (below) of the layout of the component end of the listening room is really messy, but the location of two of the AC duplexes will likely be shifted to the following locations:

1) all six duplexes will be on the ground
2) "Cluster 1" - one will be near the HRS EXRD "double width" component rack, where a single PS Audio Powerplant will provide power to the components
3) four will be located in the space near the powered loudspeakers and the monoblock amplifiers
4) "Cluster 2" - one in the center near the speakers will power a single PS Audio Powerplant

Excluding the two active loudspeakers and two monoblock amplifiers which will each have their own dedicated 20A duplex, the remaining components will be at the following two locations:

Cluster 1 - powered by a single PS Audio PowerPlant
1) Aurender N30 music server
2) Aurender N30 music server's power supply
3) SACD universal transport with I2S output
4) MSB Technology DAC (Cascade or Sentinel)'s Digital Director ("DD")

Should the Aurender be "upgraded" to Taiko's Olympus which has a large footprint of 19" x 19", the HRS rack will need to be changed to a larger size of 21"W x 19"D (instead of the standard size of 19"W x 17"D).

So, might as well go with the larger 21" x 19" size?

And, should there be a need to add an analog TT playback system with its preamplifiers, etc. in the future, there's horizontal expansion space for an additional rack. However, very long XLR balanced interconnects will be necessary to deliver the signals to the monoblock power amplifiers, something I'm not keen on doing.

Cluster 2 - powered by a single PS Audio Power Plant
1) MSB Technology DAC (Cascade or Sentinel)'s power supply chassis
2) MSB Technology DAC (Cascade or Sentinel)'s analog DAC chassis

The Cascade DAC's two chassis are very thin at 4.2" each, so when stacked they will not occupy much vertical space, and therefore ideal for placement between the two loudspeakers without causing undesirable diffraction. However, the Sentinel DAC's two chassis will be "double height" at 9.0" each, so should stacking them not be desirable sonically they can be split to the L and R (using longer XLR balanced interconnects to cover the extra distance).

Note that:
1) the digital source signal will be transmitted via optical cable, from the DD to the DAC
2) the DAC's output signal will be delivered to the monoblock amplifiers directly, with no preamplifier
3) the length of the XLR balanced interconnects can be kept very short, at less than 1.75m each to maximize signal transfer

 

[MarkusBarkus]

^^^big wow.sweet.^^^

 

[Chrisl]

“Wow” indeed.

 

[mtemur]

I don’t want to spoil your enthusiasm but you should use solid core cable. Multi stranded AC line for hifi is not good choice. It’s always been slow and lean. You may not accept it and probably will ask why but long story short, it will never ever be like a solid core. Sorry.

 

[QuadDiffuser]

I don’t want to spoil your enthusiasm but you should use solid core cable. Multi stranded AC line for hifi is not good choice. It’s always been slow and lean. You may not accept it and probably will ask why but long story short, it will never ever be like a solid core. Sorry.

Sure, would consider substitution of the current 7-strand copper cable conductor, to a solid core cable. What is the exact gauge which you've been able to install in your setup?

However, I've found that even the 4mm2 (12 AWG) solid-core conductors to be nearly impossible to bend easily, hampering installation. Is there a more malleable variant (with special extrusion) which you've found to be the solution?

What might be the audible tradeoff between using a thin 4mm2 solid-core conductor, versus a 7-stranded 10mm2 multi-stranded conductor? You mentioned that multi-stranded in wall AC cabling are comparatively slow and lean. What might a list of "Best to Worse" in wall AC conductor cables look like? I'm assuming that the Live and Negative legs of the individually insulated conductors will be tightly spiraled to mitigate transmission of common-mode RF/EMI noise (without any external shielding), with the Ground wire run separately between duplex and the MCB.

My rationale for using the latter is the superior current delivery ability of the thicker conductor, whose potential audible negatives would be mitigated through being redirected into a PS Audio Powerplant 15 (20), as well as through dedicated toroidal isolation transformers spec'd to be 6-10x the anticipated steady current draw of the component being isolated.

 

[QuadDiffuser]

The installation of my house's new utility power cable has been disrupting road access for a couple of weeks, as workers dug a big underground trench, to be re-asphalted later.

I trust that the Anaconda-like cable will be more than adequate to deliver 138KVA (400V line-to-line, or 200A) of 3-phase 50Hz 240V power to my house. Should I be worried that the 4-conductor 120mm2 cables (with 47+ individual conductors) are multi-stranded, and not solid core?

 

[Paul1960]

The installation of a new utility power cable has been disrupting road access for a couple of weeks, as workers dig a big underground trench, to be re-asphalted later.

I trust that the Anaconda-like cable will be more than adequate to deliver 138KVA (400V line-to-line, or 200A) of three-phase 50Hz 240V power to my house. Should I be worried that the 4-conductor 120mm2 cables (with 47+ individual conductors) are multi-stranded, and not solid core?

View attachment 143997


View attachment 143998

What is the function of that ring of alternating copper and aluminium (?) conductors on the outside? Grounding or shielding or ??? And you are having that run to your house?

 

[MarkusBarkus]

Should I be worried that the 4-conductor 120mm2 cables (with 47+ individual conductors) are multi-stranded, and not solid core?

...I would like to be around for that! "Back on the truck boys, I ordered solid core!" Which would weigh god-knows-what per foot. Thanks for the cool pics!

 

[QuadDiffuser]

QD
For an alternative take on side first reflections .. I worked with an acoustic engineer on these studios and to avoid the non correlated reflections from diffusers we worked out sloping reflector absorbers that bent at ear level .. this ensured sound was reflected away from listener and reflections were specular.. for ceiling we did baffles to stop reflections as much as possible

All this only works down to a certain frequency of course but it worked quite well .. you could keep qrd's if you desired and slope them similarly.

I used a similar idea in my room and it works quite well compared to qrd's I have had in the past
You end up with minimal targeted treatment and can add diffusion and absorbtion in non critical areas if you need to tame the room more
A thought to add to the mix
Phil
View attachment 119095

Phase-CORRECT diffusion vs. phase-SCRAMBLED diffusion

Hi Phil (and folks on WBF):

Regarding the differences between phase-coherent (hemispheric) diffusers and phase-scrambled diffusers (QRDs), I believe that the latter is superior, provided that minimum distance requirements are fulfilled, because the former will potentially ADD to the CONFUSION of the ear-brain hearing multiples of sound sources identical to the original sound source.

Yes, the amplitude ("loudness") of phase-correct reflections are favorably diminished through redirection, and absorption (inherent in typical materials used to build hemispherical diffusers) to mitigate the confusion of multiple direct sounds.

However, isn't it always better to DELIBERATELY randomize/scramble the phase from the onset using QRDs, so that the direct sound coming out of the L/R stereo loudspeakers is the only sound which is "phase-correct"?

What do YOU think about the veracity of the assertion (in the video below) that phase-correct diffusion is "better" than phase-scrambled diffusion?

I think that the reasons purveyors of "thin and light" Mickey Mouse room treatments criticize He-Man size/weight quadratic diffusers have little to do with ultimate performance in optimizing articulation and soundstaging, but related more to marketing and sales:

1) cheaper - more affordable, at ~1/10 the price
2) lighter - cheaper to ship, at 1/20 the weight
3) better WAF - aesthetically more pleasing with the usage of colored fabrics
4) less space needed - occupying less 1/10 the volume
5) easier installation - can be hung/placed virtually anywhere
6) proximity forgiveness - does not require a minimum distance of 8-15ft (to the listening seat position), especially important in smaller listening rooms and studios

Am I missing something in my understanding of the advantages of QRDs over hemispheric diffusers?

 

[QuadDiffuser]

Sure, would consider substitution of the current 7-strand copper cable conductor, to a solid core cable. What is the exact gauge which you've been able to install in your setup?

However, I've found that even the 4mm2 (12 AWG) solid-core conductors to be nearly impossible to bend easily, hampering installation. Is there a more malleable variant (with special extrusion) which you've found to be the solution?

What might be the audible tradeoff between using a thin 4mm2 solid-core conductor, versus a 7-stranded 10mm2 multi-stranded conductor? You mentioned that multi-stranded in wall AC cabling are comparatively slow and lean. What might a list of "Best to Worse" in wall AC conductor cables look like? I'm assuming that the Live and Negative legs of the individually insulated conductors will be tightly spiraled to mitigate transmission of common-mode RF/EMI noise (without any external shielding), with the Ground wire run separately between duplex and the MCB.

My rationale for using the latter is the superior current delivery ability of the thicker conductor, whose potential audible negatives would be mitigated through being redirected into a PS Audio Powerplant 15 (20), as well as through dedicated toroidal isolation transformers spec'd to be 6-10x the anticipated steady current draw of the component being isolated.

There seems to be a strong endorsement of solid-core copper conductors over multi-stranded for in-wall AC cabling in the WBF thread below:

In wall cables for EU 230V circuit

I’m evaluating an upgrade to be realized next spring along with a “light refurbishment” of my room (again). I have 5 dedicated lines from a dedicated panel that run separately to 5 Furutech SWS NCF wall sockets. Currently I’m using common 2,5 mm2 wires, phase neutral earth each, at least common...

www.whatsbestforum.com

Accordingly, I'm asking my cable manufacturer to quote/provide the following:
- solid core copper conductor
- 6mm2
- XLPE insulation
- color coded in brown (Live) and blue (Neutral)
- twisted together tightly (more than 8 rotations/m)
- XLPE sheath

Out of my six AC duplexes, only two will be used to power source components, and it's in these that the 6mm2 solid core copper conductors will potentially shine.

I will build a double run of PVC conduits to these two AC duplexes, so that I can install both the thinner and (purportedly better-sounding) 6mm2 solid core in-wall AC cables, and the thicker (allegedly leaner and slower sounding) 10mm2 multi-stranded in-wall AC cables. I will thus be able to audition both AC cables and select the one which I like better.

Most critically, the MSB powerBase and MSB DAC (both located at the proximity of the MSB mono block amplifiers) will be the beneficiary of this audition-driven choice of either the 6mm2 solid-core or the 10mm2 multi-stranded in-wall AC cabling.

Transmission of 50Hz 240V AC power across distances involve a multitude of physical phenomena, mostly in the realm of electromagnetism, much which can be modeled from what we currently understand from physics, but potentially a lot which we don't yet understand. I'll let my ears/brains be the final arbiter, but I must first anticipate, plan, and build in the optionality, to have the choice later, to select between the two different in-wall AC cable configurations based on audition results.

 

[pjwd]

Phase-CORRECT diffusion vs. phase-SCRAMBLED diffusion

Hi Phil (and folks on WBF):

Regarding the differences between phase-coherent (hemispheric) diffusers and phase-scrambled diffusers (QRDs), I believe that the latter is superior, provided that minimum distance requirements are fulfilled, because the former will potentially ADD to the CONFUSION of the ear-brain hearing multiples of sound sources identical to the original sound source.

Yes, the amplitude ("loudness") of phase-correct reflections are favorably diminished through redirection, and absorption (inherent in typical materials used to build hemispherical diffusers) to mitigate the confusion of multiple direct sounds.

However, isn't it always better to DELIBERATELY randomize/scramble the phase from the onset using QRDs, so that the direct sound coming out of the L/R stereo loudspeakers is the only sound which is "phase-correct"?

What do folks think about the veracity of the assertion (in the video below) that phase-correct diffusion is "better" than phase-scrambled diffusion?

The reasons purveyors of "thin and light" Mickey Mouse room treatments criticize He-Man size/weight quadratic diffusers include:
1) cheaper - more affordable, at ~1/10 the price
2) lighter - cheaper to ship, at 1/20 the weight
3) better WAF - aesthetically more pleasing with the usage of colored fabrics
4) less space needed - occupying less 1/10 the volume
5) easier installation - can be hung/placed virtually anywhere
6) proximity forgiveness - does not require a minimum distance of 8-15ft (to the listening seat position), especially important in smaller listening rooms and studios

Am I missing something in my understanding of the advantages of QRDs over hemispheric diffusers?

Hi QD
I have always understood that both types mess with phase at a single listening point .. the curved surface reflects earlier at different points so you have time differences.. there also is potential of lobing if they are multiple units (1same goes for qrd)
Against this you have the proposal that a reduction of 10db between direct and reflected sound is adequate to deal with non correlated reflections. I am not sure that this is optimal though..
Similarly a time difference of 10ms is an alternative target

I have built both types and ultimatly didn't like either (there is an improvement but still lacks clarity)

I prefer a redirection of the reflected sound via angled flat panels that preserves the corelation but direct reflected sound away from listening spot.
I am also a fan of doing this with first and second reflections which gets a little complex but achieves a long time gap as well as lowering db (I think)

These panels can have a degree of absorbtion to calm the room as this non correlated reflection is directed away from the ear

A bit different from the norm but it seems to make sense

 

[pjwd]

Hi QD
I have always understood that both types mess with phase at a single listening point .. the curved surface reflects earlier at different points so you have time differences.. there also is potential of lobing if they are multiple units (1same goes for qrd)
Against this you have the proposal that a reduction of 10db between direct and reflected sound is adequate to deal with non correlated reflections. I am not sure that this is optimal though..
Similarly a time difference of 10ms is an alternative target

I have built both types and ultimatly didn't like either (there is an improvement but still lacks clarity)

I prefer a redirection of the reflected sound via angled flat panels that preserves the corelation but direct reflected sound away from listening spot.
I am also a fan of doing this with first and second reflections which gets a little complex but achieves a long time gap as well as lowering db (I think)

These panels can have a degree of absorbtion to calm the room as this non correlated reflection is directed away from the ear

A bit different from the norm but it seems to make sense

I should add to the above.. you want a delay from the direct sound of 10ms and then a reverbarent tail that is correlated with the direct sound ... that will give the best rendition of the room acoustic of the recording .. it's not a reverbarent field in the strict definition of large space acoustics but you get the drift

 

[Daniel Francis]

I trust that the Anaconda-like cable will be more than adequate to deliver 138KVA (400V line-to-line, or 200A) of three-phase 50Hz 240V power to my house. Should I be worried that the 4-conductor 120mm2 cables (with 47+ individual conductors) are multi-stranded, and not solid core?

I am in awe and also quite jealous you get such a connection for a residential home. We struggle to get connections like that for commercial here in California. Were you able to secure your own transformer from the utility??

 

[QuadDiffuser]

Hi Daniel!

I remember from my visit to MSB Technology's very impressive HQ in April 2023, including the tree trunk like utility mains cables and the HUGE breaker box. How much power were you able to secure for your facility - 400A, or more?

We're in a neighborhood densely packed with mostly residential houses, the majority having just 60-100A of electricity, typical of what's practically needed. This I know from simply walking around the block, as by law the main breaker box for every house is installed at the entrance, thus visible from the street level.


According to information available from the electric utility company's website (see above), each substation delivers up to 5,000kVA. A step-down transformer will not be necessary; by splitting the 3-phase power source into three separate single-phase branches, the conversion of 400V down to 240V happens "automatically", as per the diagram in this earlier posting:

My dedicated audio room build - QuadDiffusor's Big Dig

I've got my eyes on MSB's upcoming Sentinel DAC, featuring 32 Hybrid DACs (16 per channel), compared to the Cascade DAC’s 8 Hybrid DACs (4 per channel). Its design is evolving, recently haven gone through its 2nd round of prototyping and testing. Read about the Sentinel DAC's design updates on...

www.whatsbestforum.com

I requested 200A, and happily there was enough capacity from the sub-station located down the road, for which I paid ~$12k (+tax) for the cabling, installation, and a larger breaker box. The kVA equivalent for 200A of power would be 138kVA (see chart below), a bit less than 3% of the substation's total capacity of 5,000kVA.

My house will also have on its roof 28pcs. of 450Wp of solar PV panels for a total of 12.8kWp, feeding a single inverter which will be grid-tied. Since there will be no storage batteries, whatever power the solar system generates which is not consumed during the daytime, the excess will be sold back to the utility company. Hopefully, the solar system will not pollute my audio system's AC power source, but that's another topic for another occasion.

 

[Daniel Francis]

Hi Daniel!

I remember from my visit to MSB Technology's very impressive HQ in April 2023, the tree trunk like utility mains cables and the HUGE breaker box. How much power were you able to secure for your facility - 400A, or more?

We're in a neighborhood densely packed with mostly residential houses, the majority having just 60-100A of electricity, typical of what's practically needed. This I know from simply walking around the block, as by law the main breaker box for every house is installed at the entrance, thus visible from the street level.
View attachment 144117

According to information available from the electric utility company's website (see above), each substation delivers up to 5,000kVA. A step-down transformer will not be necessary; by splitting the 3-phase power source into three separate single-phase branches, the conversion of 400V down to 240V happens "automatically", as per the diagram in this earlier posting:

My dedicated audio room build - QuadDiffusor's Big Dig

I've got my eyes on MSB's upcoming Sentinel DAC, featuring 32 Hybrid DACs (16 per channel), compared to the Cascade DAC’s 8 Hybrid DACs (4 per channel). Its design is evolving, recently haven gone through its 2nd round of prototyping and testing. Read about the Sentinel DAC's design updates on...

www.whatsbestforum.com

I requested 200A, and happily there was enough capacity from the sub-station located down the road, for which I paid ~$12k (+tax) for the cabling, installation, and a larger breaker box. The kVA equivalent for 200A of power would be 138kVA (see chart below), a bit less than 3% of the substation's total capacity of 5,000kVA.

My house will also have on its roof 28pcs. of 450Wp of solar PV panels for a total of 12.8kWp, feeding a single inverter which will be grid-tied. Since there will be no storage batteries, whatever power the solar system generates which is not consumed during the daytime, the excess will be sold back to the utility company. Hopefully, the solar system will not pollute my audio system's AC power source, but that's another topic for another occasion.


View attachment 144115

Very nice. We have 400 Amp service at our factory with a dedicated transformer. It was the largest service they would allow in this space, but we would have loved to go for more. Before getting our own transformer, we could see the neighbors industrial equipment polluting our mains so clearly... but perhaps the residential setting is more forgiving.

Not having batteries may be more of a boon than you expect, Jonathan just installed batteries and they cause audible hums from all appliances in the house. Compared to the solar inverters, the batteries are quite offensive. In California, the utility will no longer pay for excess power, so without storage, our daily excess is wasted.

 

[QuadDiffuser]

Thanks for sharing, Daniel. Wow, tough constraints you've had to overcome.

Batteries are not allowed here, given the density of the residential homes not having adequate buffer space to hedge and isolate the worst-case scenario of combustion accidents.

In Jonathan's installation, the buzzing and noise may be a case of stray DC which wreaks havoc on equipment running on AC. Hope he can find a solution to those nasties.

Oh wow, I didn't know; utilities no longer paying for excess power - what's the logic for that change? From a win-win, to a lose-lose!

 

[Daniel Francis]

Oh wow, I didn't know; utilities no longer paying for excess power - what's the logic for that change? From a win-win, to a lose-lose!

Politics I suppose. After the many California wildfires being pinned on PGE, this is part of their revenge towards the people. Ha! It is a very antagonistic relationship.

Also, with the addition of so many electric cars and generally more people, our power grid is failing to keep up. This is to incentivize residential and commercial battery installation to help alleviate some of the demand.

My solar agreement expires next month, I will go from 90% buyback rate to near zero overnight... time to install batteries -_-

 

[wil]

Very nice. We have 400 Amp service at our factory with a dedicated transformer. It was the largest service they would allow in this space, but we would have loved to go for more. Before getting our own transformer, we could see the neighbors industrial equipment polluting our mains so clearly...

Daniel, I’m curious how you measured the influence of your neighbor’s industrial pollution to your service?

Did you measure at your mains supply?

Did you see distorted voltage and current sine waves, high harmonic distortion, poor power factor…?

Thanks

 

[Daniel Francis]

Daniel, I’m curious how you measured the influence of your neighbor’s industrial pollution to your service?

I didn't directly do the measurements, I'm the mechanical guy over here. Vince Galbo has a lot of experience poking around on power if you interested in reaching out to him. He is always pretty happy to discuss.