Articles, Reviews and Measurements of Audio Products

This is a review and detailed measurements of the Peachtree GAN400 stereo balanced (input) amplifier. It is on kind loan from a member and costs US $2,499.

I am not generally a fan of peachtree audio product looks but this one in coffee stain looks pretty good. Other than a power switch, not much else is there. Ditto on the back side:

The claim to fame of this amplifier is use of GaN transistors which in theory simplify the design of a class D amplifier (a bit) and improve its efficiency (a bit). And in theory, it can also produce lower distortion (in open loop anyway). The drawback is much higher cost of the transistors compared to MOSFETs. Let's see if the performance is there.

Peachtree GAN400 Measurements
I performed all of my testing using XLR input. Let's start with our usual input of 1 kHz with output into 4 ohm to the tune of 5 watts:


There is fair bit...

This is a review, listening tests, EQ an detailed measurements of 1More Sonoflow Noise Cancelling Bluetooth headphones. It is on kind loan from a member and costs US $99 although goes on sale for $79.

The look and feel of the unit belies its low cost. The plastic seems stout and good quality. Pad feels soft and I like the nice large channel indicators in the red inserts. An app comes with lets you control the unit although I found the buttons very intuitive as well -- unlike many others I have tested.

Alas, the cups are just a bit too small to fully cover my ears so I can't wear them long term. I could not achieve identical response for each cup over my GRAS 45C measurement gear so consider what you are about to see approximate.

1More Sonoflow Measurements
There is provision for wired access which turns off the unit. Where possible I use to test headphones...

This is a review, listening tests and detailed measurements of the Avantone Pro MixCube compact monitor speaker. It is on kind loan from a member and costs US $259.

As you can see, the unit is quite compact sporting in a single driver. Enclosure is quite hefty and solid with glossy finish. Back side shows a large heatsink indicating class AB amp (?). And one of the heaviest outboard power supplies I have seen:


Company advertising starts with: "The black Avantone Active MixCube Powered Full-Range Mini Reference Monitor is a professional studio reference monitor specifically tailored to produce the useful musical range of 90 Hz to 17 kHz."

Let's see if it delivers on that.

Measurements that you are about to see were performed using the Klippel Near-field Scanner (NFS). This is a robotic measurement system...

This is a review and detailed measurements of the DAC portion of the Emotiva ERC-4 CD player. It is on kind loan from a member and costs US $649.

The display lights up in classic, intense dark blue colors of Emotiva. I am not a fan of it as it is old fashioned. Not much functionality is here other than acting as a DAC with inclusion of S/PDIF and Toslink inputs:



Wish there was a USB input however. On positive front, the remote is metal, feels substantial and has a cool, magnetic back to open and replace the AA batteries. LIke the XLR outputs and high quality RCA connectors.

As noted, this is a test of the unit using it as a DAC. I wanted to test it as a CD player as well but my test CD had broken in half.

Speaking of something broken, so was the ERC-4. It would not function even though the front panel controls were operational. I took the top off and noticed the ribbon cable plug was loose:
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This is a review and detailed measurements of the Denon AVR-X4800H 9.4 home theater receiver. It was kindly drop shipped by a member and costs US $2499.

While the look is the same as previous generations, the feel of the control knobs is much improved which I appreciate. Menu system is also modified. Importantly there is now a per-pair selection to disable amplification on any two adjacent channels. We finally have a very good solution for selectively adding external amplification. Here is the back panel:


AVRs usually take a long time to measure due to multiple subsystem and myriad of settings that can impact measured performance. On top of doing that, I ran the measurements by Denon which provided some feedback on a couple of problem areas. Upon retesting the...

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...