Hypex Nilai(R) 500 DIY Mono Power Amplifier


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Hypex Nilai(R) 500 DIY Mono Power Amplifier

By Alex Colburn

The Class D amplifier was invented back in the 1950’s with truly practical amplifiers not appearing until the 1970’s. In 2003 Hypex moved into Class D with the introduction of the UcD (TM) (Universal class D) series of amplifiers which quickly became an industry standard employed widely in HiFi and pro audio. Then in 2011 Hypex introduced the NCORE (R) series of amplifiers, a new technology with a 20dB boost in feedback loop gain (Loop gain in Class D should not be equated to that in linear amplifiers) and resulting in 10 times better performance. For me, NCORE (R) represents a point when Class D amplification came of age as a serious competitor for linear amplifiers to the extent that my main amplification has been exclusively Class D since 2016.

Moving on to late 2022 Hypex introduced another new technology, “Nilai(R) which apparently means “value” in Malay, a name somewhat appropriate for the DIY market. Hypex has always strongly supported the DIY community, choosing to release their latest technology to the DIY community first and Nilai (R)is no exception in this. The Nilai(R) technology features a triply nested feedback loop with first order bandwidth roll-off, improving loop gain and bandwidth. Hypex claim Nilai(R) is another 10-fold increase in performance across the board over NCORE(R) and this is reflected in the measured figures on the data sheet adding zeros after the decimal point in the distortion and output impedance figures. Taking these vanishingly small figures literally would imply Nilai (R)is 100 times better than UcDÔ, but of course, these things are never linear. NCORE(R) was a big step forward from UcD (TM) so it will be interesting to see where Nilai(R) stands in relation to NCORE.(R) Nilai(R) also boasts a custom designed discrete input buffer rather than the usual op-amp buffer. The monoblocks use a new power supply designated PS500DIY which features audiophile components and interleaved power factor correction to increase power density and lower electromagnetic interference.

Kit assembly

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Nilai 500 DIY monoblock kit

Since the WAM has a very strong DIY community it’s particularly appropriate to review the Nilai (R) as a DIY kit from the ground up rather than a completed amplifier. The kit comes very neatly packed in a compact tri-wall box including all the electronic and mechanical parts with virtually zero wasted space. Whoever designed the box deserves a medal, how often do items arrive in poorly designed packaging with acres of empty space which ends up just filling the bin with cardboard!


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Electronic assemblies, wiring looms and hardware

Assembling the Nilai(R) 500 kit is very straightforward since the instruction booklet is predominately graphical with comprehensive images covering the identification of parts and each stage in the assembly process. For those interested, a preview of the assembly instructions can be found here: https://www.diyclassd.com/media/f0/6b/1c/1678454093/Nilai500DIY Mono-kit Assembly_R2.pdf

There is also a useful animated video of the assembly process available here:

The kit includes the specialist tools that are required such as Torx and small hex keys, any additional tools like pliers and a small flat-blade screwdriver will generally be available in the average household.


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Monoblock case components

Having studied the instruction manual and identified all the components, the first stage in assembly is to bolt the PSU and amplifier module to the pre-drilled baseplate. The PSU has 7 small mounting pillars and requires a pre-drilled and threaded transition plate to position all the base mounting screws within the base plate. Interestingly, the only thermal path for heat dissipation from the PSU to the case is via the 7 small pillars which points to the very high efficiency of this new PSU design. In comparison, the PSU’s used in the NCORE(R) series of amplifiers have a very substantial heatsink which is bolted directly to the casing. The Nilai(R) 500 amplifier module is bolted to the baseplate with 4 screws and Hypex says that the efficiency of the amplifier means it does not need heatsink compound to enhance thermal conductivity to the baseplate. Unusually, the amplifier module heatsink comes with a semi-mirror finish which may play some role in mitigating the thermal requirements.



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PSU and amplifier module mounted on baseplate

Stage two adds the U-shaped side panels to the baseplate which are held in position by the screws for the 25mm diameter machined aluminium feet. Each foot has an O-ring partially rebated into its surface to provide non-slip furniture protection. I found it beneficial to leave foot mounting screws loose by half a turn as they tend to bring the upper edges of the side channels together when tight making it difficult to slide in the top case panel and also insert the rear panel screws. The feet screws should only be tightened once the rear panel and top plate have been fitted. Next the front panel mounting brackets are screwed to the side panels which provides a neat screw free fixing for the front panel.



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Side plates, input power loom and front panel brackets fitted

Stage three is the longest phase and covers the assembly and fitting of the rear panel. The supplied speaker terminals are a substantial gold-plated variety able to accept 4mm plugs, fork connectors or bare wires. With the rear panel having two 45° spaced mounting lug notches for each speaker terminal, by removing and rotating the speaker terminal base to the desired position they can be mounted in any one of eight positions according to your own preference. The speaker terminals are fixed in position with an insulating washer and a nut which is best tightened with a 12mm spanner. A short wiring loom with gold-plated fork connectors is at one end, and bootlace ferrules at the other end, connect the speaker terminals to the amplifier module. Two opposing grub screws in the terminals are used to firmly clamp the bootlace ferrules. A push-fit IEC power inlet with integral fused live is pressed into the rear panel and the two T6.3A anti-surge fuses (one fuse is a spare) are fitted in the integral pop-out fuse holder. A single pole push-fit mains switch is pressed into the panel above the power inlet, which should be inserted with the correct polarity shown in the diagrams. The mains wiring loom connects to the power inlet and switch using spade connectors, so care is needed when following the wiring diagrams to ensure the mains live is connected to the correct terminal on the PSU. The balanced XLR input connector is mounted on a PCB assembly incorporating the external trigger socket and a three-position toggle switch to control the front panel LED brightness (high-off-low). The input module is swung into the back of the rear panel and secured with two self-tapping screws. Two wiring looms are connected to the input module before fixing the completed rear panel to the case with four screws.


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Assembled rear panel

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Rear panel mounted, speaker and power looms connected

Stage four is the important step of fitting and dressing all the internal wiring, following the Hypex instructions carefully to avoid any unwanted electromagnetic interference that could otherwise affect performance. All the internal wiring is fitted with polarised connectors at both ends except for the speaker and mains wiring looms so it is a good idea to test the insertion of these before assembly, none should require significant force to mate properly. A short earth wire connecting to the power inlet is firmly bolted to the base panel of the case to fulfil mains safety requirements. The gold-plated fork connectors on the speaker connection loom are clamped into the amplifier module receptacles taking care to observe polarity and the wire is carefully dressed away from the input module. A short wiring loom connects the input module to the amplifier module which should be dressed in a simple vertical loop away from other wires. The wiring loom from the PSU to the amplifier module requires a single twist to align the correct polarity for the PCB connectors and should dress itself naturally in a simple vertical loop.



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All internal wiring connected and dressed

Stage five is the final assembly, fitting the remaining PCB, top panel and front panel. The front panel PCB has the power/stand-by switch and indicator LED and is mounted above a recess on the rear of the front panel with two screws allowing the switch and LED to protrude very slightly through the panel. The ventilated top panel is slid into the top grooves of the side panels and held in position without fixings. The bottom edge of the front panel has two holes to take hex key grub screws which should be screwed in halfway. After connecting the remaining wiring loom to the front panel PCB, the panel is lifted onto the front of the case so it rests on the mounting brackets. By holding the panel down and in at the bottom, the lower edge grub screws can be tightened onto the lower edge of the mounting brackets and thereby locking the panel onto the front of the case. Finally, the feet screws can be tightened up locking everything together and the Nilai(R) 500 is now ready to be tested!


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Ventilated top panel and front panel fitted

Assembly of the first kit took a little over one hour but the second kit only took 30 minutes with the whole process being pretty painless due to the excellent instructions. Both amplifiers powered up without any problems and I checked the DC offset on the output terminals to make sure they were safe to connect to the speakers. The rear mains switch powers up the PSU into standby mode and pressing the miniature push button above the front panel LED powers up the amplifier as confirmed by the illumination of the LED. A moveable jumper on the Nilai module allows you to set the overall gain of the amplifier to 11.68dB, 21.75dB or 27.88dB, I chose 21.75dB to best match my system. The monoblocks run nice and cool, after several hours they only reached a modest 32°C so the electricity bill is not going to suffer.

Audition

All listening tests were conducted using a Linn Klimax DSM with Organik DAC as a digital source and driving a pair of modified Townshend Glastonbury Tor Mk1 speakers augmented with Townshend Maximum Supertweeters. These speakers are not particularly sensitive at 88dB/W 6W and do respond well to power delivery. Source material was derived from a local NAS or streamed from a Qobuz Sublime account.

Starting with classical, Stravinsky’s The Rite of Spring-Pucinella Suite, Yoel Levi Atlanta Symphony Orchestra 16bit/44.1kHz. It was clear that the lower frequencies were being presented with great solidity enhancing the perceived depth with no apparent smearing. Timpani was fast with natural depth and power and three-dimensionally stable. Michael Moore’s tuba playing was exceptionally full-bodied with great texture as was double bass. Imaging of the entire orchestra showed effortless depth and height extending beyond the speakers.

Moving on but staying with the classical genre, Mussorgsky’s Pictures at an Exhibition: Jean Guillou at the Great Organ of the Tonhalle, Zurich 16bit/44.1kHz is a well-known tour de force for any HiFi system. The Kleuker & Steinmeyer organ played in this piece was newly installed in 1988 and was based on a design conceived by Jean Guillou himself. So, a virtuoso musician playing an instrument designed by themself should be something special and I was not disappointed with the Nilai (r)’s reproduction. The organ was dimensionally well presented with each rank of pipes precisely defined all the way down to the 32’ monsters heavily featured in The Great Gate at Kiev. The attack and decay of notes were cleanly and naturally modulated by the acoustics of the hall imparting feeling and reality to the performance.

By way of comparison but also contrast because Pictures at an Exhibition was originally written as a piano piece, I listened to Mussorgsky’s Pictures at an Exhibition: Night on a Bald Mountain, Lorin Maazel The Cleveland Orchestra 16bit/44.1kHz. As with the Stravinsky, timpani was very solidly portrayed with good tonal character. The preponderance of wind instruments in this piece showcased the NilaiÒ’s ability to clearly and accurately present this class of instruments which many amplifiers fail to do.

Agnes Obel: Aventine 24bit/44.1kHz is a fine recording of piano and female voice. The piano was reproduced very well with an “in the room” feel to it and the closely miked voice displayed a haunting and wonderfully breathy quality. As the recording is densely layered with cello and plucked strings it can be challenging but the Nilai (r)' s succeeded in maintaining good separation of instruments.

Yamato: Aozora (The Drummers of Japan) 16bit/44.1kHz. A good recording of Japanese Taiko drumming is a stringent test of speakers and the ability of power amplifiers to drive them. The frequency range spans from the largest O-daiko drum all the way through to the smallest Shime drum and is topped with hand bells. Attendance of a live performance of Taiko drumming is needed to appreciate the sound and feeling to expect from a HiFi system. The Taiko technique integrates copious rim shots which add higher frequency content to produce a unique sonic quality. The Nilai’Òs delivered the best Taiko performance I have had from the system; the physical soundstage is necessarily large in all three dimensions (the O-daiko drums are mounted on a frame several feet above the stage) which was reproduced convincingly, and the high frequency content of the drums had the effect of locking them into the stereo image. Depth and power of the drums were very good and begs the question of how much current was being delivered into the speaker terminals at the 80 - 90dB SPL I was listening at. Throughout the audition, despite the demand I was putting on the Nilai(R)s, they failed to gain more than a couple of degrees in temperature.

Conclusions

My current amplifier is the Nord Three SE 1ET400A Mk II dual mono version which I found surpassed the performance of my earlier Hypex NC500 based amplifier. Based on Purifi technology with the Nord pro opamp custom input buffer, the 1ET400A does most of what the Nilai(R) 500 does in terms of sonic quality but not as well as the Nilai(R)s do. To sum up, the Nilai(R)s are seriously good amplifiers and at some point will migrate into commercial products but as a DIY kit they offer exceptional value for money. There is a cheaper stereo version of the Nilai amplifier available as a kit but since both channels share a single PSU it only delivers about half the power and therefore not a fair comparison to the monoblocks.

The Hypex Nilai (r) 500 mono power amplifier kit costs: €820 excluding VAT and shipping and can be purchased direct here: https://www.diyclassd.com/products/diy-amplifier-kits/nilai500diy-500w-mono-power-amplifier-kit

The kit is also available from some dealers in the UK who also offer a ready-built option for a relatively modest fee.

The review amplifier kits and title picture are courtesy of Hypex Electronics B.V.

(r) registered Trademark
(TM) Trade mark

Associated review equipment:

Source: Linn Klimax DSM Organik

Speakers: Modified Townshend Glastonbury Tor Mk1/Townshend Maximum Supertweeters

Interconnects: Nordost Tyr 2 balanced XLR

Speaker cables: Nordost Heimdall bi-wired Z-plugs

Power cables: Nordost Heimdall 2
 
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