@Graeme_Finlayson - Your preferred brand has just posted an interesting test on XLR cables.
@All - But the very interesting part starts at 08:00: SMPS vs. LPS
Torben
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Great video, interesting that this was posted today… maybe they’re taking old videos hosted elsewhere and putting them on YouTube?
This application note describes in more detail why this cable configuration works.
Like @Graeme_Finlayson I’m consistently impressed by John Siau and Benchmark. I don’t have the same technical knowledge as Graeme, however I do have a fairly well honed BS detector. I’m a happy consumer of Benchmark products for what that is worth.
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Great video. Thx for sharing. And although this makes perfectly sense - I can feel a war arising 
John Siau busting more audiophile myths! 
The thing about Benchmark’s cables is that they’re standard Canare Starquad microphone cable with Neutrik XLR connectors.
A pair of 3-foot cables costs US$84.
They’re hard to get in the UK, so I bought them from a UK based cable supplier who makes them from the Canare cable and fits the Neutriks. Same as Benchmark’s, just without the logo.
I also made a bunch of my own using Van Damme Starquad which is easier to obtain in the UK to connect up my Focusrite Scarlett 2i2 for REW measurements.
Both cables perform equally and are cables that are widely used in the recording industry and at musical performances the world over.
The LPS die-hards constantly talk about “noise” from SMPS. A good SMPS puts all of the switching noise way out of the audio band. As John clearly demonstrated, the biggest issue with LPS is magnetic leakage. Even toroids, which have the least amount of magnetic leakage, still spray magnetic fields from the area where the cables exit the windings.
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Those small charger type supplies also put out lots of noise, and they are the SMPS’s everyone complains about and replaces. The aim is to get a good PSU. A good PSU can be either linear or switched mode. So a more appropriate title of this thread should be good vs. bad PSU’s.
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Another title could be good vs. bad engineering. The DAC1 was released about 20 years ago, had that large magnetic interference generating transformer in the chassis and still performed very well relative to competing products in the day. It was engineered to accommodate the power supply that it had.
The newer DAC3 has a different power supply which emits less magnetic noise (or emits noise elsewhere in the EM spectrum) but it doesn’t affect the performance of the unit. Indeed, they state that you can stack Benchmark DAC3/LA4/AHB2 without issue. Other competing products are also resistant enough to interference that it is not worth worrying about.
However some products apparently cannot be run optimally without purchasing a completely different power supply. Does that mean that linear or switching is better? Or that the device in question is not sufficiently resilient to the real world?
EDIT: the stated point of the video was to present the noise canceling ability of star-quad in a balanced system. Benchmark embeds this in their circuit boards (correct me please if I am incorrect here). That indicates that they do not expect their devices to live in some sort of laboratory environment. You can put them in your HIFI cabinet.
That is incorrect. This is purely about the cables. Demonstrating the noise generated by the transformer in their DAC1 compared to the SM supply in their later DAC was just for comparison. The DAC1 doesn’t suffer any inherent problems in normal operation. I had one for quite a few years.
Also note that this can also be fixed by proper routing of conventional cables. The entire point of pro rated cables is they will tend to be much longer runs than at home, and that you may not have the luxury of careful routing in a pro environment. Does anyone use cables as long as in that video at home?
The video is illustrative, not scientific. And it is star quad vs. conventional cable. As both types of PSU cause issues in the video it certainly can’t be touted as one type of PSU vs. another.
NB. You can’t embed this in circuit board design because this is about cable construction and implementation. All Benchmark do is make sure the circuit is fully differential from input to output.
Not all of them put out lots of noise and most of those who replace them do so indiscriminately without first establishing whether there’s an issue.
I’ve said this many times before, and I’ll say it again. If an audio device performs poorly with a cheap SMPS, then the audio device isn’t adequately designed.
Many audiophiles don’t have a clue what makes a good PSU. They just latch on the the concept that SMPS=BAD and LPS=GOOD and then go and do stuff like add a LPS to a computer…
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But there are good and perfectly understood reasons why replacing a poor PSU anywhere in your system can provide perceived improvement. PSU’s need to be benign both into the device they power and the mains they are powered from. A case in point was the original supply provided with Logitech (SB) Touch device. It was replaced by the manufacturer when it was discovered by an enthusiast that the audio band noise it injected into the mains impacted his vintage gear. He measured and published the result. Power supply design has to be cognisant of the system it is placed in, not just the device it powers.
System = the end to end process of producing music from ISP device to speakers.
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That’s a very isolated case.
One could also argue that the vintage gear’s PSRR wasn’t adequate for modern mains supply.
Mains is noisy and should be expected to be noisy, especially with the amount of electrical devices around these days employing inverter drives - washing machines, AC units and with a lot of solar PV around, DC to AC inverters.
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I’m sure there are those running active systems with much longer cables than that.
Totally agree.
Poor design is actually quite common. This is the reason that mix and match of components can yield surprising results. In the high end this is especially true. The high end budget being mostly consumed by marketing and cosmetic considerations and the lack of any significant sales volumes to offset R&D. Some of the best designs are relatively cheap because the components in an excellent design don’t need to be super expensive and design costs can be spread out over a high volume of units.
Many of the very worst designs are nose bleed expensive.
The SMPS story in audio relates to the evolution of transistor switching speed - in the past SMPS had too much noise close to the audio band - no longer the case. Modern SMPS can be designed just as Benchmark describes and making it the best overall power supply while remaining inexpensive. SMPS means a much smaller footprint (Iower cost chassis) compared to a linear power supply with a toroidal transformer. The disadvantage is a small box has less appeal in high end due to the lack of big is better boat anchor vibe.
Mcintosh have achieved good low noise preamplifiers for years - however they use a separate shielded box to host the power supply and the amps are necessarily very big or like their top of the line are housed in separate boxes.
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I realize the video was about the cables. I was extending the discussion to the device as a whole and the care taken to account for real world noise. I found the reference to which I was referring here.
See the section “IMMUNITY TO MAGNETIC INTERFERENCE”. I interpret that as doing something similar to star quad in the circuit board, ie four traces rather than two arranged in a way to allow rejection of common mode noise.
@Rhythmatist - Good point.
I think the problem is also, that everyone talks about how great LPS is, but nobody takes about how great SMPS is. There are MANY sites about ““great”” LPS - but no sites about about SMPS.
The only SMPS that I know of that should be good is iFi iPower Elite, if you need an external SMPS.
Are there other good SMPS (external)?
Torben
The IpowerX is also a SMPS and costs roughly a third of the Elite. I’m using it with the Zen Stream, with good results. I’m following this discussion with great interest. Thank you for sharing your thoughts and experience.
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Look for the name Meanwell. They make an assortment of internal and external supplies and the companies that care sufficiently about this use them or companies like them.
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