⌈ ACOUSTIC REVIVE is a Japanese company that was set up in 1997, run by Mr. KEN ISHIGURO-san. It specializes in connectors and anti-vibration products, but also offers innovative devices, most often the brainchildren of the University of Tokyo. We are testing one of the company’s products that filter ground interference – the RGC-24K. ⌋

he ARTIFICIAL GROUND, OR – as the Acoustic Revive company calls it – GROUND CONDITIONER is one of the products that the Japanese manufacturer has been offering for the longest time. When it started to be manufactured, it was acknowledged in Japan as the emanation of experience in industry, while the so-called “West” welcomed it with disbelief and suspicion, as another example of audiophile “voodoo”. After many years, once again, it appeared that when it comes to innovativeness and courage to look for new solutions, but mostly to imagination, we lack something, indeed.

“Conditioning” the ground of electronic circuits, including ones that convert audio signal, is an obvious thing and a norm today. Many other manufacturers from all over the world, including Poland, are offering similar products nowadays. However, at least for me, Acoustic Revive has remained a pioneer in the field. Nevertheless, even pioneers conceive still better ideas once in a while – like in this case. The tested ground conditioner is another (already a third) element of the new generation products of this Japanese company, one built by Mr. Ken Ishiguro using a material called Kiyoh-stone.

Let me remind you that the previous ones have been the:

• RWL-3 ABSOLUTE acoustic panels; review HERE,
• RPC-1K passive AC filter; review HERE,
• RCI-3HK cable lifters.

▌ RGC-24K

⸜ APPLICATION The ground conditioner coded as RGC-24K by the manufacturer serves to minimize interference from the ground of an electronic circuit. As we can read in the company’s materials, the “RGC-24K fixes chassis electrical current and electric outbreak by virtual ground environment. This leads to stability in circuit moment, which improves sound.”

Like all other circuits of this type, the tested Acoustic Revive product is connected to the ground of the only device that it is going to be used with. It can be done using a ground clamp, if the manufacturer of the given device had thought about it, or by connecting the RGC-24D to any RCA input or output. In the latter case, it is assumed that the ground of an electrical circuit is at the same time the ground of the whole device. It is not always like this, but it works out in 99% of cases.

The artificial ground that we are talking about also works in a similar way to the passive EMI / RFI VERICTUM X BLOCK filter, so it combines two products in one. To make use of this function, you need to place the ground conditioner under the transformer supplying power to the given device.

⸜ DESIGN The RGC-24K has the form of a small, but heavy disc which measures 88 x 18 mm and weighs 384 g, to which a 50-centimeter cable is connected. The disc is made of anodized, titanium-colored aluminum and a brass base. Inside there is a copper element to which the ground is connected from the outside. The element is immersed in a mixture of natural minerals with a minus electrical current potential. It is known that it is a blend of rock crystal and powdered tourmaline, which releases negative ions. It is a crystalline boron-silicate material that belongs to the silicate family, consisting of elements such as aluminum, iron, magnesium, sodium, lithium and potassium; a semi-precious stone.

Similarly to the previous products that we have already mentioned, the name RGC-24 now features the letter ‘K’. Let me remind you that this is short for ‘Kiyoh-stone’. Elia Hontai-san from the Muson company, which represents Acoustic Revive outside Japan, wrote that Kiyoh-stone is a rare earth element, the main ingredient of which is aluminum silicate. It is available at only one location in the Land of the Rising Sun, in Gunma Prefecture. As he says, this is no coincidence, because the seat of Acoustic Revive is located in the same prefecture.

The property of this material, which Mr. Ishiguro-san was keen on, is that it easily generates high intensity negative ions, the maximum of which is in the far-infrared rays. Kiyoh-stone generates up to 40 times more ions than tourmaline. Mr. Elia Hontai adds that it is one of the more expensive materials of this type available on the market, and only in limited quantities.

The ground potential of the given device is connected to the RGC-24K using a 50 cm cable. It is an interconnect that the company has been selling for some time now. It used to be made of oval OCCC copper wires, while now it is made using Triple-C copper (read more about Japanese copper manufacturers HERE |PL|). The cable also incorporates ferrite filters manufactured by the Japanese company Fine Met.

The owner of the Acoustic Revive company is a perfectionist (I am sure about it, as we have known each other for years), which is demonstrated in details. In this case, it is about the terminals of the abovementioned cable. On the one hand, it has a fixed wonderful banana plug manufactured by the company itself, the RBN-1 model with rhodium-plated contacts. It is placed at the ground conditioner’s end. When it comes to the other end, where the “conditioned” device is connected, there is a small fork terminal which can be connected to a ground terminal that can be found in any Japanese product. However, if a given device is not equipped with such a terminal, one can use the RCA IP-2 plug, used by the company to minimize noise and vibrations, which is part of the product set.

▌ THE LISTENING SESSION

⸜ THE WAY WE LISTENED The Acoustic Revive ground conditioner RGC-24K was tested in the HIGH FIDELITY reference system and compared to a similar product from the NORDOST company, the QKORE model. The device from the American manufacturer is part of our reference system, so I know it well. The basic difference is that the version of the QKore that we are using can ground six products, while the RGC-24K – one.

I connect the QKore ground to individual devices and the power strip using the same manufacturer’s cables with different terminals. As all the unused connectors in the AYON AUDIO CD-35 HF EDITION player, apart from BNC connectors, are equipped with special noise damping elements (Acoustic Revive) at their ends, the player is connected using a cable with a BNC connector. I changed that for the purposes of this test and used the Nordost cable with an RCA connector at the end. Both the QKore and RGC-24K were connected to analog inputs no. 3.

The manufacturer recommends placing the ground conditioner under the transformer, as the device also operates as a passive EMI/RFI filter. As transformers in the Ayon player are situated at the front, I put the RGC-24K there. To put it closer to the transformer, I placed it on a Vibrapod isolator. It was an A/B and A/B comparison with known A and B.

Albums used in the test | a selection

⸜ ANDRZEJ KURYLEWICZ QUINTET, Go Right, Polskie Nagrania „Muza”/Warner Music Poland 4648809, „Polish Jazz | vol. 0”, Master CD-R (1963/2016);
⸜ DEPECHE MODE, Construction Time Again, Mute/Sire/Rhino | Reprise Records 2-108732, „Collectors Edition”, Promo CD-R + DVD-R (1983/2007).
⸜ DEPECHE MODE, The Singles 86>98, Mute/Reprise records 2-47110-AB, „Album Advance”, 2 x Promo CD (1998).
⸜ EMMYLOU HARRIS, Pieces Of The Sky (Expanded & Remastered), Reprise Records/Warner Bros. Records/Rhino R2 78108, „Work CD-R”, 2 x CD-R (1974/?).
⸜ KEITH JARRETT, Creation, ECM Records/Universal Music LLC (Japan) UCCE-1150, Promo CD-R (2015)
⸜ STAN GETZ/JOAO GILBERTO, Getz/Gilberto, Verve/Lasting Impression Music LIM K2HD 036, K2HD Mastering, „24 Gold Direct-from-Master Edition UDM”, Master CD-R (1964/2009)
⸜ THE OSCAR PETERSON TRIO, We Get Request, Verve/Lasting Impression Music LIM K2HD 032, K2HD Mastering, „24 Gold Direct-from-Master Edition UDM”, Master CD-R (1964/2009)

FROM MY EXPERIENCE, all artificial ground circuits work in a similar way, at least in general. However, they do differ when it comes to details, which may lead to us choosing one manufacturer over another. In the comparison, it was like this with the RGC-24K – it did things similar to what the Nordost QKore does, but in another way, so the end result was different.

The American artificial ground is very impressive. The changes that it brings are big, repetitive and instantly audible. At the same time, however, as I see it now, it is also a bit “crude”. There is nothing wrong with that and it is a great point of reference for other manufacturers, but products such as the RGC-24K still go a bit further. The basic difference is that the Acoustic Revive ground conditioner allows for more subtle sound differentiation. It is not as impressive as the Nordost device, though one can also instantly hear that it “works”, but you need to spend some time with it, listen to a few albums and… think, in order to understand what this is all about.

The Japanese ground conditioner made both OSCAR PETERSON’S piano and RAY BROWN’S double bass from the album We Get Request, played from a Master CD-R with a First Impression Music remaster, more subtle, as one could hear more detail with it – everything that makes an instrument seem “natural”. Slight changes in piano pedaling make the instrument sound a bit different and it was clearer with the Japanese device in the test, thanks to which the piano itself also sounded more clearly.

What is interesting, sound taken as a whole was darker and deeper with the KGC-24K. The treble was better differentiated, but the change was not as big as with the QKore – the Nordost device does more in this respect. There were much greater changes in the midrange that was more “focused”, but had larger volume, was darker, but still clearer, more “within one’s reach”.

Not long before the test, I finished reading a monograph on the album Getz/Gilberto by BRIAN McCANN. Published by Bloomsbury Academic as part of the series “33 1/3”, it focuses on the musical aspect of the album and its cultural context. It clearly states that the only person who really benefitted from the album’s popularity and was not overcome by the success was ASTRUD GILBERTO, the girl who appears on the album at exactly 1:22 of the first track. On the wave of popularity of bossa nova in the USA, she gave concerts, released albums and finally retired on her own conditions – no big dramas, no fails and recoveries. Considering that time and the musical industry, it was a big achievement, indeed.

Anyway, even the first sounds made by JOÃO GILBERTO, which turn into singing in a moment, showed that the Japanese ground conditioner somehow makes sound quieter, on the one hand and clearer on the other hand. I had not missed anything before – the vocal that was placed a little to the left was large, dense and dark, the leader’s guitar was recorded in a way for it not to have any clear “center” and was larger than in reality because of a phase shift, while the piano could be heard on the right – it was great.

However, with the RGC-24K the sound became even denser, but also clearer. The drums, located by the album producers at the extremity of the left channel, sounded clearer, more precise and natural, even though they seemed to be even quieter and more withdrawn than without the ground conditioner connected to the Ayon player. Astrud’s vocal was less infantile and more nuanced with the Japanese device. It was still a young and inexperienced singer, but there was more emotion and warmth in her singing than when I listened to her without the conditioner.

However, we do not need such refined music to hear changes introduced by the Acoustic Revive ground conditioner. It is enough for one to have any well-produced album. In order to confirm that, I reached for a pre-premiere issue with the compilation of DEPECHE MODE greatest hits, entitled The Singles 86>98. As I have already said, such issues are pressed right after test presses, using a still fresh matrix, so they have the most in common with materials supplied to the record label on a mastering medium.

And, who knows, but with such albums you will be most impressed by what the RGC-24K does. Sound was still great without it, but kind of less lively, less dynamic and less tangible. Dave Gahan’s vocal from the track Behind The Wheel, placed far away in the mix, was clearer and more audible, but still lower and deeper with the ground conditioner connected to the player. The sound of this track without the Acoustic Revive device was heavier, but also less differentiated and less “lively”.

▌ CONCLUSIONS

IT WAS LIKE THIS WITH EACH of the albums. The changes were repetitive and using the Acoustic Revive ground conditioner always resulted in more nuanced and deeper sound characterized by better resolution than achieved without the tested device in the system. When it comes to better resolution, it mostly refers to the depth of the soundstage, like on the copy of the album by EMMYLOU HARRIS entitled Pieces Of The Sky (Expanded & Remastered), released in the USA by Rhino, where the vocalist’s voice had more marked reverberation (it was similar with Gahan’s vocal) and the guitars were shown in more natural surroundings.

The Nordost QKore works equally well, but in a different way. It offers a little cruder, but at the same time more obvious changes in the sense that they are more striking. The “Grounding Conditioner” RGC-24K is more subtle and refined, though the changes it brings have a smaller volume. However, it is a perfect alternative both for the Nordost device and Polish products manufactured by Verictum and Thunder Melody. It is interesting that even though the method of reducing ground interference is similar, the sound effects are different.

The RGC-24K is an expensive, but excellent addition to any audio system – from medium-priced (most interference occurs in them) to high-end ones. I do not know if the “K” version differs from the previous one (when it comes to sound), but here and now it is simply a great product which improves the sound quality of the system that we already have, without changing its character. With the Acoustic Revive product we simply get more of everything in a better form. ■