HIFI-TUNING SUPREME³ Fuse holder - Automatic circuit breaker - Hifi-Tuning
HIFI-TUNING SUPREME³ Diamond - Fuse holder - Automatic circuit breaker - Hifi-Tuning

Hi-Fi Accessories · Power Supply

Every watt of power that becomes music in a hi-fi system has to pass through one inconspicuous bottleneck first: the circuit breaker in the distribution board. Whatever constrictions, contact resistances and material compromises hide there shape the sound long before the signal even reaches an amplifier. Bernd Ahne of HiFi-Tuning in Berlin has spent years working on exactly this point in the chain — and with the Diamond Supreme³ Fuse Holder he has built the most uncompromising answer the market currently has to offer.

In terms of pure materials, the design pushes things about as far as they can go: pure copper conductor paths, silver-plated, then re-coppered and finally gold-plated in three stages, with the entire assembly cryogenically treated in a nitrogen bath. Non-magnetic stainless steel screws replace conventional fasteners. A proprietary Quantum treatment follows, along with a few additional steps that remain Bernd Ahne's trade secret. The result is a holder that is already considered the sonic benchmark in its standard Supreme³ form. The Diamond version then adds the decisive final step on top — the natural diamond on the front face.

For decades the hi-fi community has experimented with the influence of crystals on current-carrying conductors — from tourmaline granulate and quartz-filled blanking plugs to rock crystal placed on tube amplifiers. What has long been dismissed as esoteric is in fact uncontested among materials scientists: crystalline structures act on metallic conductors in their immediate vicinity. The effect may evade simple measurement, but it is audible all the same.

Bernd Ahne is not the kind of engineer who spends time on theoretical debates — he simply tries things. For the Diamond Supreme³ fuse holder he ordered a wide range of high-purity natural diamonds and systematically compared their sonic effect when placed near the metal end caps of his fuses. His conclusion is unambiguous: a genuine high-purity diamond, positioned just a few millimetres from the fuse, delivers a more powerful, more open soundstage with an audible gain in dynamics.

Specifically, the holder uses a natural diamond, 3 mm in diameter, brilliant cut — the largest stone in the entire HiFi-Tuning Diamond range. It is mounted on the front of the holder so that it sits very close to the fuse without making any electrical contact. The asymmetric placement is deliberate, not a sign of careless craftsmanship — the acoustically optimal position dictates the geometry. Tests with larger diamonds yielded a more striking visual but no further sonic improvement. Ahne has settled on the point where effect and material expense meet in optimal balance.

The base of the holder comes from a renowned international industrial supplier — building such a part in-house, complete with all required certifications, would be economically out of reach for a small company. What HiFi-Tuning does with it, however, has nothing to do with industrial mass production. The pure copper conductor paths are first silver-plated, then re-coppered and finally gold-plated in a multi-stage galvanic process. This seemingly absurd effort serves one clear purpose: long-term stable conductivity well beyond standard brass or simple silver plating — without the corrosion susceptibility of pure silver over years of operation.

Inside the holder, non-magnetic stainless steel screws replace the standard fasteners — magnetic fields anywhere in the signal path are sonically undesirable. The completed assembly is then cryogenically treated in a nitrogen bath in Berlin: at temperatures far below freezing, the crystal lattice of the metals realigns more uniformly, internal stresses are released, and the internal resistance drops measurably. A proprietary Quantum treatment follows, along with further processing steps that remain Bernd Ahne's trade secret to keep imitators at bay.

Compared directly with the already excellent standard Supreme³ holder, the Diamond version brings another clearly audible step up: more clarity, more space, more depth, more dynamics, more authority. The entire presentation gains a more lifelike, effortless character — voices stand more sculpted in space, bass lines gain substance and contour, the treble refines without becoming hard. Because the holder sits at the central power feed for the entire system, every connected component benefits equally — turntable, preamp, power amp, DAC, streamer and source devices alike.

To put the magnitude into perspective: experienced listeners compare the leap to upgrading to high-quality aftermarket equipment feet — one of those measures where the sound improves in a way that cannot be replicated through equalisation or single-component upgrades. The Diamond Supreme³ holder does not act selectively on any one frequency band; it works as a general cleansing and stabilisation of the entire power supply.

The holder accepts Supreme³ fuses in the 10.3 × 38 mm format up to 32 A. In typical residential installations, 16 A fuses are used. Before fitting them, it is worth wiping the fuse end caps with a clean dry cloth to remove any finger grease — even thin oily films create additional contact resistance and would partly cancel out the meticulous material work. The fuses themselves are not included in the scope of delivery and can be ordered separately in the desired current rating.

The N-position of the dual holder ships with a solid copper bar of the same 10.3 × 38 mm format, also silver-plated, copper-plated and gold-plated in three stages. From a purely sonic standpoint, HiFi-Tuning recommends replacing this bar with a second 32 A Supreme³ fuse — the audible improvement over the plain conductor bar is clearly perceptible.

Important note: Installation of this fuse holder is strictly a job for a qualified electrician. Do not tinker in the distribution board — play music instead. Work on the household mains is subject to national electrical regulations and may only be carried out by a registered specialist.

Within the HiFi-Tuning Diamond programme, the fuse holder occupies a special place. The fine fuses carry diamonds of 1 mm (5 × 20 mm format) and 1.3 mm (US format 6.3 × 32 mm), the 10.3 × 38 mm circuit fuse uses a 2 mm stone, and the holder itself receives the largest diamond of all: 3 mm, brilliant cut. That makes the Diamond holder the most consistent application of the crystal idea in the entire HiFi-Tuning catalogue — and the logical first step before fitting Diamond fuses inside individual components. Combining this holder with a Diamond fuse essentially represents the purest expression of the approach.

Showing off the rock in your distribution board is not really an option — who opens the breaker box for guests? But you will probably listen with more pleasure. Every single day the system is running.