Articles, Reviews and Measurements of Audio Products

This is a review, listening tests and detailed measurements of the JPS LABS DIGITAL AC-X FILTERED AC CORD. It is on kind loan from a member and costs US $649.

I was pleasantly surprised that despite its girth, the JPS cord is quite flexible and lightweight (for its thickness). I suspect there is good bit of air in that oversized jacket. Sadly there are no safety regulatory marks on it.

JPS LABS DIGITAL AC-X AC CORD Measurements
Company advertises the cord for digital sources (I think) so I choose to test it with a Topping D70s which ironically costs the same as the JPS cable! Here is our dashboard with generic AC cord:



And now with JPS Digital AC-X cord:


We have the usual run to run variation. Beyond that, there is no reduction in noise or distortion. Output level and frequency are the same. Let's run 32 tones to see if this outcome changes:
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This a review, listening tests and detailed measurements of the JPS Labs Superconductor V "Ultra high-performance" USB cable. It is on kind loan from a member and costs US $1000.

The cable has a decent feel but does not want to be rotated. As you know though, the USB connectors need to be aligned by rotating the cable so this present some inconvenience and pressure on the mating connector. The cable as you see, lacks any hint of it being a premium one with mundane jacketing and such.

JPS Labs Superconductor V USB Cable Measurements
To test the cable I used my Topping D70s which sits on my desk for this kind of testing. The source is my workstation PC. I connected the two first with a generic 6 foot USB cable (double the length of the JPS). This cable is soft in hand, thinner and generally much easier to manipulate than the JPS. Here is the D70s performance with it:

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This is a review, detailed measurements and listening tests of the JPS LABS ULTRACONDUCTOR 2 1 foot XLR cables. It is on kind loan from a member and costs US $799 for a pair.

As you can see, there is no fancy braiding or termination. Cables are a bit stiffer than my reference but still pliable enough to interconnect two pieces of audio stacked up. Neutrik connectors are used which are good.

JPS LABS ULTRACONDUCTOR 2 XLR Cable Measurements
I used my Audio Precision analyzer as the "audio" source and destination to measure the performance of these cables. I used my lower cost measurement cable, the World's Best Cable (WBC) with Canare L-4E6S star quad cabling and Amphenol connectors. The WBC cables are 3 feet so at a bit of disadvantage relative to JPS cable. Let's start with wideband frequency response measurement going from DC all the way up to 90 kHz (4.5 times our hearing...

This is a review, detailed measurements and listening tests of the M-Audio BX3 powered monitor speaker. I purchased it from Amazon by request from membership. It costs US $107.

The speaker looks like many professional monitors we review. However, when you hold it in your hands, it is extremely light and pretty small. So light that its stiff power cord drags it left and right by its sheer weight! The little 3.5 midwoofer though seems to be of high quality with high excursion for its size. Back side shows pretty rich feature set:


A single cable carries the output to the slave speaker.

Measurements that you are about to see were performed using the Klippel Near-field Scanner (NFS). This is a robotic measurement system that analyzes the speaker all around and is able (using advanced mathematics and dual scan) to...

This is a review, detailed measurements and listening test of 理性派HiFi X5 speaker. It was kindly purchased by a member in China and drop shipped to me. It costs CH Yuan 2280 (USD $327) for the finish in this sample, and 1980 ($284) without per pair.

The walnut finish is quite nice and I appreciated the rounded corners and overall feel of the unit. Back panel is unusual in what it doesn't show than what it does:

And that is, lack of port. Bookshelf speakers universally have ports to improve bass response and it is interesting to see this speaker do without. Binding posts are hard to see but they are quite beefy/premium.

Speaker is not sold outside of China so I don't have an English name for it. Company designer has a large and positive reputation in China.

Measurements that you are about to see were performed using the...

This is a review, listening tests and measurements of the RSL CG25 center home theater speaker. It is on kind loan from a member and costs US $425.

This is an unusual design in that the port goes through a path in the back which kind of resembles a very short/truncated transmission channel. Otherwise we have the usual MTM configuration of dual mid-woofers and tweeter. Not much to see on the back other than the useful threaded insert for mounting it to the wall:


Build quality seems good with nice finish and reasonable weight and solidity.

I was contacting the company regarding another product so while I was at it, I asked them to review the frequency response measurements. They are generally in agreement with the results you are about to see.

Speaker was tested in horizontal configuration as you see above. Reference axis was that of tweeter.

RSL CG25 Center Speaker Measurements
As usual we start...

This is a review, listening tests and detailed measurements of the Eleven XIAudio Broadway balanced battery operated desktop headphone amplifier. It is on kind loan from a member and costs US $2,599.

As you see, the unit only supports balanced headphone output. The volume control has excellent, fluid feel that is superior to many other implementations out there. And the knurled engraving on it helps with gripping it. Back panel shows balanced only input connection as well:

As noted, the unit sports a set of batteries internally which can power the unit for a few hours. As such, the power switch is momentary to turn the unit on and off. Being class A, the box uses fair bit of power and stays warm to touch, partially defeating the feature of battery operating it.

I like the choice of Meanwell power supply which is a nice brand of switching supplies.

What I absolutely did not like where the corners and edges...

This is a review, listening tests, and detailed measurements of the 64 Audio tia Trió IEM. It was kindly drop shipped to me and costs US $2,299.

I was not a fan of included cord. It feels sticky even though it isn't. And is rather thick and has memory. Here are the included pads:


I always use the middle size silicon tips for measurements which worked out great in this case. The seal was excellent and gave proper results on first try.

This is a 3-driver design with passive crossover.

Note: The measurements you are about to see are made using a standardized Gras 45C. Headphone measurements by definition are approximate and variable so don't be surprised if other measurements even if performed with the same fixtures as mine, differ in end results. Protocols vary such as...

In several threads related to DSP platforms I've seen requests for measurements with filters engaged. I thought it unlikely that implementing filters in a DSP would have measurable effect on noise / distortion other than the obvious change in the fundamental, however @Sokel recently mentioned that he returned his miniDSP Flex after observing noise / distortion issues with filters applied. This piqued my interest as a long time DSP user and I decided to explore it for myself.

The first issue is what filters to use and what tests to run. I decided to use filters for my LXmini + sub system, this gives a convenient way to compare relative differences between DSP platforms. Here are frequency response sweeps of the three channels at -1 dBFS.



I made purely digital measurements as this gives the most resolution and the following tests.

1) 1 Hz to 48 kHz frequency sweep at -1 dBFS...

PGGB is an expensive off-line upsampler that promises an extremely high resolution reconstruction of a lower-res recordings (like Redbook), using up to 256-bit floating point computation and avoiding the need to use sinc interpolation (according to the author).

If you read the often glowing reports from customers, it makes an amazing audible difference, despite taking some very serious PC hardware and significant time to upsample existing files, often taking hours or even days to complete and requiring 4x or more times the storage of the original files. Maybe it's really worth it?

Archimago did an evaluation of PGGB previously, and used my DeltaWave software to do the null analysis among other tests. I decided to see if I can reproduce his results and provide a little more details on what PGGB can or can't do. To do this, I picked an 44.1k album to upsample and left PGGB running...