Saturday, November 19, 2022

Kojo Technology Crystal E Ground Box and Crystal EP Plug


Kojo Seiko Co. Ltd is a medium sized company located in Hirakawa City in Aomori, Japan. Established in 1990, they are involved in a variety of electronic related businesses ranging from power supply design and manufacturing to audio accessories.


The Crystal EP is a virtual earth product that improves the grounding of audio equipment. The device is a barrel shaped plug with various connectors available :- RCA, 3.5mm mini plug, banana and spades. The barrel contains 100 cm2 of high purity aluminum foil treated with a special etching process to create cavities that increase the surface area to 11,000 cm2. The rear of the Crystal EP plug unscrews to accept a grounding cable for connection to the optional Crystal E Ground Box. 

The Crystal E Ground Box is a compact metal ground box that houses an eight layer plate structure that functions as a virtual ground. The plates comprise a combination of stainless steel, brass and copper plates. The plates are stacked, with a 0.5mm air gap between each plate. The box measures 80mm (W) x 35mm (H) and 111mm (D) and weighs 775 grams.

Picture taken from Kojo's website

There are two screw terminals at each end of the box. One terminal is used to connect the grounding cable to the component or Crystal EP plug, while the other end is used to daisy chain a second Crystal E Ground Box. Two ground cables of 1.2m length are thoughtfully provided in the package, one with spades on both ends, and the other with a spade and RCA plug.

You can use the Crystal EP plug alone, or connected to one or more Crystal E Ground boxes. Alternatively you could use the Crystal E Ground connected directly to the component in question. 

To be continued ....


Saturday, September 10, 2022

Grimm MU1 Music Player

Grimm MU1 Review

Grimm Audio was founded in 2004 and is based in Eindhoven, The Netherlands. Helmed by Eelco Grimm and Guido Tent, Grimm is well-known in professional audio circles.

Grimm claims that the MU1 is the ultimate digital musical source. That's certainly a bold claim - let's see whether the MU1 performs as claimed.


Underneath the hood, the MU1 runs its software on a Linux-based Intel i3 computer board and an in-house designed FPGA board which runs format and sample rate conversion. An ultra-low jitter clock (<0.6 ps RMS (>10 Hz)) completes the picture. Hey, it’s a Grimm and you wouldn’t expect anything less would you?

At the moment, the MU1 is a Roon-based solution that acts as both Roon Core and Roon End-Point. There are plans to offer a DLNA solution in the future though. Tidal and Qobuz support are available through the Roon app, but Spotify Connect is not supported. 

The MU1 is available with internal music storage of up to 8TB. Otherwise, you can use network storage or an external drive connected to the twin USB 3.0 ports on the MU1.

Three digital inputs (AES, coaxial and Toslink) are provided which allows the MU1 to process external data streams, allowing other digital sources to enjoy the goodness of the MU1.

The FPGA upsamples the data stream to either 2x or 4x of the sampling rate before being sent to the two AES or single coaxial digital outputs. A fourth digital output via an RJ45 port serves as a proprietary connection for the Grimm LS1 speaker. The digital outputs may also be configured for 6-channel output for surround sound use. No preamplifier ? No issue – there is a digital volume control on hand too. As there is no way to attenuate DSD streams, conversion to PCM is required to make use of the volume control.  

Setting Up

Hook up the MU1 to your network via its LAN port (wireless connection is not available), switch on the power, and you are ready to go. The difficulty factor depends on how familiar you are with Roon. As a long-time Roon user, setup was straightforward. The well-written manual is comprehensive, and I spent less than an hour setting up the MU1 and loading my test tracks into the internal drive. The unit connected to the internet and prompted an upgrade to its firmware. Grimm has worked hard in the past to upgrade the performance of the MU1, so you can expect steady improvements in performance over time.


The giant wheel on top of the unit controls the MU1. With a combination of short/long presses and turning the wheel, you can access the various menu options. Most users would navigate their library and operate playback through the Roon App, whether running on their mobile phones or a tablet.

The sampling rate conversion can be switched to “Original”, “2FS Oversampling” or “4FS Oversampling”. If “2FS Oversampling” is selected, files at 44.1 and 48 kHz sampling rate will be upsampled at 2FS, while 88.2 and 96 kHz sampling rate files will be played at their native sampling rate. In the case of files over the targeted oversampling rate, they will be downsampled (e.g. 8FS and DSD material). The MU1 also supports DoP in case the user prefers to play DSD files natively on their DAC.

The USB port can also be enabled to output data, but I found it sounded inferior to the AES and SPDIF outputs when paired with my Totaldac D1-Six DAC. 

Programmable remote-control operation is possible if an external IR receiver is connected to the 3.5mm jack provided on the rear of the unit. As I did not have an IR receiver on hand, this function was not tested.

Sound Quality

The MU1 is simply the finest quality Roon playback I have heard bar none. The tone is a fluid, almost analog-like quality with powerful dynamics and extended highs. My Roon ROCK (Roon Optimized Core Kit) server runs on an Intel i7-based NUC fitted into a fan-less Akasa Turing chassis for fully passive cooling. The MU1 ran rings around my home rig, to the point that the performance gap between the two was simply unbridgeable.

One very important caveat is that the performance lead of the MU1 depends on your source material and how you employ upsampling (or not). The lead narrows considerably if you are playing  DSD natively, or PCM files without upsampling. I am personally not a big fan of upsampling, but the MU1 does this in a way that improves sound quality so significantly in terms of separation and detail that you will just leave the upsampling enabled permanently.  

If you are a DSD fan and your DAC does not support DoP, operation will also be cumbersome. You will need to change your Roon settings to output the digital stream via the USB port, which then leaves you without upsampling. You could connect up your DAC via the SPDIF or AES output, and toggle between the two signal paths, but the routine will quickly become old. The other alternative would be to stick to the SPDIF or AES output, and convert all DSD streams to PCM – something bound to offend a DSD purist!

Coming back to the sonics, there is a certain rightness to the MU1. Bass is very tight and powerful, and piano notes have a rich solidity and realism that fills the room. The midrange is on the warmer side of things, and vocals have a warmth and richness that is creamy and inviting. This is coupled with very extended and clear high frequencies that reveals plenty of detail and air. Counter-balanced with the hefty low-end and warm midrange, you end up with a tone that is not bright at all, yet highly detailed and easy to listen to. This is not a product that plays the neutrality card, but instead takes the path of connecting emotionally with the listener. 

The way the MU1 produces music is very special - music is highly energetic, yet natural and non-fatiguing. Your brain instantly registers that the MU1 is a rare and outstanding product that stands out from the crowd. 

Closing Thoughts

This is a niche product. If you dislike Roon or want ruler-flat neutrality, you should look at something else. Some audiophiles would balk at the price-tag of the MU1 and insist that this is an overpriced computer server build. An audition should quickly sort that out. I know of several experienced audiophiles and reviewers that purchased the MU1 after experiencing what it brings to their system. Although the outcome would be Grimm for my bank account, I definitely want one! Highly Recommended.

Grimm MU1 Music Player

Price - S$16,000 (excluding GST and with 4TB SSD internal storage)

Grimm products are available from :-

Sound Affairs Pte Ltd

110 Lorong 23 Geylang #06-03
Victory Centre
Singapore 388410

Saturday, February 5, 2022

WFH Special #2 - Creative Outlier Air V3


Not a fan of wired headsets for your office conference calls? Consider true wireless in-ear-monitors as an alternative. Lightweight and comfortable, they are a more practical choice in tropical weather if you do not run air-conditioning. 

Apart from office use, they will be perfect for accompanying you for your exercise sessions, or travelling. This makes them an easy sell to the Minister of Finance at home. 


The Outlier Air V3 ("V3") is the third-generation version of the Outlier Air - Creative's true wireless in-ear-monitors. 

The charging case remains at about the same size as the original Outlier Air ("V1") which means that it is bulky and clunky to carry around. Sharing the same footprint, the V3 case is slightly taller. You do get 40 hours of playtime though with 10 hours per charge, which is improvement over the 30 hour lifespan of the original model. The case may be charged via a USB-C port, or Qi-compatible wireless charging. Charging time via cable is between 2 to 3 hours.

The V3 uses Bluetooth V 5.2. Supported audio codes are AAC and SBC. Purists will be disappointed to note that aptX support has been dropped. Like the V1, the V3 is IPX5 certified for water resistance. 

The driver for the V3 uses a 6 mm bio-cellulose driver, which is a change from the 5.6 mm graphene-coated drivers used in the V1. 

The V3 case, fully loaded with earbuds weighed in at 76.6 grams, compared to 61.8 grams for the V1. The earbuds for the V3 are 5.3 grams in weight (per side), while the V1 are 5.1 grams. 

By default, the usual volume and play control functions, Siri or Google Assistant, as well as ambient and active noise reduction modes are accessible via touch control. However, you can also customise the controls via the Creative App. This App is also used to flash firmware upgrades and applying EQ settings.

Besides the Creative App, you will need to download the SXFI App to transfer your personal profile over to the Outlier Air. Music also has to be played through this App in order to enjoy SXFI. This is an inconvenience, especially if your music source is from a streaming service since the App supports playback of local music files only.  

Use, Fit and Comfort 

Taking the earbuds out of the case will put the V3 into pairing mode automatically. You also have the option of just using one side (useful for conference calls). I noticed that the earbuds would also squeal loudly when being returned to their case. I traced this to feedback from the microphones when either ambient mode or active noise reduction is being used. Alternatively, place the earbuds back in the case one at a time to avoid this. 

Fit will be subjective. The V1 with its larger shell, fitted my ears better and provided a better seal. The V3 felt less secure, and did not seal as well in my right ear. However, this can be easily remedied by changing out the tips to suit your personal preference. The V3 sat quite securely during exercise sessions, although I would feel less confident to use them for long runs. They were also comfortable enough to be used for long listening sessions.

Battery life was consistent with specifications and the V3 had no issue connecting with my phone placed about 6m away so long as line-of-sight is maintained. 


The V3 turned in a competent performance, with a significant improvement over the V1. Bass performance was tighter and more impactful, while midrange was much clearer - the V1 had a tendency to sound muffled and nasal. High frequencies also had a touch more openness and extension. Soundstaging on the V3 was also wider and more spacious, with better placement of voices and instruments. 

Tonally, I would say that the V3 had a slightly warm balance, with neutral bass and highs, and a laidback midrange. Some listeners may find the bass balance a bit light, but this can be fixed in the EQ settings.

Putting aside the richer feature set, the V3's sonic performance is reason enough to upgrade from the V1. 

The active noise reduction works reasonably well. However, as the name suggests it attenuates outside noise instead of canceling it. Nevertheless, the end result is good enough for the typical home environment, or for traveling. 

The microphone pickup is above average and voice pick-up is reasonably clear.  


The V3 is a solid performer at a bargain price. The Singapore online shop regularly runs promotions, and you can usually get a pair at a good discount - Best Buy

Creative Outlier Air V3

6 mm Bio-cellulose Driver
Battery Type and Life
Battery in Charging Case: 1 x Rechargeable Lithium Polymer Battery 450 mAh, Battery in Earbuds: 2 x Rechargeable Lithium-ion Polymer Battery 55 mAh
Charging Time
2 to 3 hours
Connector Type
Bluetooth 5.2
Audio Codec
Weather-proof Resistant
Price - S$ 99