BlockAudio was founded by two HiFi and music enthusiasts because amplifiers available on the market failed to meet their expectations in terms of sound, finishing or the price performance ratio. Their first pre/power amplifier combination has a price of 70,000 Euro. No, this doesn’t mean you can smirk, it is not a contradiction: Their amplifiers convince in all three criteria.
Jiri Nemec and Dan Oudes have been working together since 2003; they were enthused by the speaker building kits from Dynaudio and built speakers together. In the Czech town Olomouc, Dan Oudes operates the HiFi store AudioStudio and imports products from notable manufacturers like Bryston, Dynaudio, Plinus, Thales etc. Jiri Nemec is a qualified communications-, measurement- and control engineer, who worked in Austria at the Philips plants in Vienna and Althofen. His special professional interest lies in the development of automated measurement series with Audio Precision equipment. In 2013 the company BlockAudio s.r.o. was founded and already within the same year they exhibited at the klangBilder show in Vienna. This is where I saw the impressive amplifiers for the first time and introduced them elaborately in the show report.
![Nomen est omen]()
No matter whether the aluminium, natural anodized amplifiers back then, or those with the black Nextel look: whoever sees these exceptional, professionally manufactured components would never assume that they originate from a small manufacturer. One fascinating aspect in the HiFi scene is that individuals or, like in this case a small company, with a lot of personal investment and suitable suppliers, can bring products to the market that compete with the high-class products of companies like Harman, even in terms of processing and manufacturing efforts. Admittedly, for Levinson amps the design would have probably been less modest and with a higher glamour factor, but I personally like the deliberately discrete design of BlockAudio very much. Here, form follows function.
![The Monoblock features two pairs of speaker terminals. The energy is taken from a IEC 60320 C19 connector. Therefore, I had to refer to the supplied power cables]()
In automotive and watch manufacture, withdrawing from series production and moving in the direction of individual manufacture in most cases means multiplication of the price when compared to similar products – at least in terms of function. This is not the case for BlockAudio as the first glance at the amps already shows: For the above-mentioned price, you get a strictly channel separated preamplifier with a battery power supply in a separate case. The two mono power amplifiers are dimensioned for 200 Watt in Class-A and weigh 90 Kilograms each. However, it is not only about the mere use of materials: Jiri Nemec and Dan Oudes also emphasize that no visible screws disrupt the simple elegance of their creations. The pars pro toto for the diligence that went into every detail of their amplifiers, are the cabinet's feet: Two of the three feet under each device are height adjustable, so that the components are perfectly placed in a horizontal position. According to Jiri Nemec this is especially important for the Power Block, as here the two transformers for the supply of the audio circuit boards are mounted hanging. During transport, they are secured by tightly screwing in of the feet. Instead of a spike, the feet have a steel ball which deduces vibrations to an area of 10 by 10 millimetres of Widia tool steel. A piece of merino wool felt under each foot protects the underlying surfaces. The structured surface of the feet rounds up the positive overall appearance.
![The BlockAudio has a switch for sensitivity and can be operated in Class-A or Eco-Mode. Error messages are shown on the device but also on the display of the in-house preamplifier when both are connected through a RJ-45 connector]()
The preamp power supply case not only contains the two battery power supplies for the audio circuits, but also a third conventional power supply, which supplies the control circuits and the display for the preamplifier. Of course, all three power supplies are electrically isolated from each other. This goes as far as that three cables are necessary for the mains connection – the Line and Power Block might well become the favourite preamplifier of all cable manufacturers. The audio part of the preamplifier consists of four blocks: the anterior one, which contains the circuit boards for control and monitoring electronics, as well as the display and the operating controls for volume and input selection choice. The cases for signal processing of the two stereo channels are found at the back on the left and right side. The slightly shorter block in the middle has the – unfortunately single-ended – input sockets for the phono preamplifier in the back as well as a single-ended headphone socket in the front. Therefore, when using them, the otherwise strictly separated grounds of the left and right channel have to be connected per relay.
![Here you can see one of the eight El-Caps of the power supply for the Class-A power amplifier]()
For the phono stage the gain can be selected by menu including the input impedance for Moving Magnet or Moving Coil cartridges. A Subsonic filter can be activated and for MC cartridges loads are available at 10, 15, 30, 40, 50, 70, 100, 200, 300, 600 and 1000 Ohms and for MM pickups capacities at 50, 100, 150, 200, 250, 300, 350, 400 pF – all comfortably adjustable by remote control. For this and only this, BlockAudio goes the easy way and packs the Alu-Remote from Apple as a remote control. The control block of the preamplifier also has two RJ-45 sockets. If they are connected to the power amplifiers, you not only can switch them on remotely, but you can also choose between Class-A continuous operation, Auto Eco or Eco mode. In Eco mode the Monoblock in idle state only uses 50 Watt instead of 500 Watt in Class-A operation. If Auto Eco is chosen, after 15 minutes without audio signal at the inputs of the power amplifiers, the system will automatically switch to the power-saving Eco mode and the bias current is only increased, once an input signal is present.
![Each power amplifier is fed by a 2,500 VA transformer.]()
Through the cable connections the Monoblocks report the temperature of the power transistors at the preamplifier where they are then shown on the display. In my relatively small listening room the temperatures easily reach 60°C, and if the windows are closed and the room temperature increases they can possibly be a couple of degrees more. Thus, the Class-A bolides ‘heat’ a little more than Einstein's OTLs. Good, that I deal with the OTLs and Class-A-Monos before it gets really warm outside. However, those who can afford a pair of the likewise fantastic and tonal slightly different Einsteins or BlockAudios, most likely will also have a larger and thus airy listening room than mine is… However, before I start sharing my experiences from the listening room, it will not harm you to get a little more information about the techology of the BlockAudio. But you won’t get this from me, neither as an audio-file to listen to straight from he developer as in the review of the Kawero!. Holding an interview, including editing on the Digital-Audio Workstation is even more labour intensive than writing about it. My colleague Roland Dietl, who is more than skilful in the area of circuit technology, has kindly offered to take over this task, leaving me with a little more time to prepare for the High End show:
![The capacitors for the power supply of the input stage and drivers]()
„I had the chance for a detailed talk over FaceTime with Jiri Nemec on the technical concept behind the devices and the solution approaches he used. These are not entirely new however, but captivate through uncompromising implementation to the smallest detail, and give a good impression of what is really important. Let’s start with the mono power amplifier, which impressively demonstrates what real Class-A operation at 200 Watt output power into 8 Ohms actually means – respectively a huge power dissipation of 500 Watt in idle operation (!), which leads to enormous heat development that has to be deducted through large heat sinks at both sides of the device. For such capability a suitable power supply is needed first. Jiri Nemec likes to compare the power supply of the power amplifier with the engine size of a car, as it is commonly known that there is nothing to replace this. Following this philosophy, a massive 2,500 Watt toroidal transformer can be found at the power amplifier, which even at maximal output power into 2 Ohms is 2 to 2.5 times over-dimensioned. The filtering of the rectified AC voltage for the power part is done by eight high performance capacitors with a capacity of 47,000 μF each. For the voltage supply of the small signal parts there are further power supplies and filtering capacities resulting in availability of an overall capacity of around 0.5 Farad. With the mostly constant current output due to Class-A operation, the power supply should behave like a regulated voltage supply.
![Attention to detail: BlockAudio device feet with steel ball and Widia base plate in the interior]()
The rectifier diodes are connected to the heat sink through heat pipes. Jiri Nemec has kept the audio circuitry itself relatively simple. It is a fully discrete construction, DC coupled, has a DC-Servo that regulates DC residues and does not need capacitors in the signal path. Jiri Nemec works with a quite strong feedback, without which it would not be possible to reach the enormously high damping factor of 5,000. At the input stage there is a differential amplifier with JFETs and the subsequent voltage amplifier stage is built with a combination of MOSFETs and bipolar transistors. In the output stage on each of the two heat sinks work 8 bipolar, 200 Watt power transistors from Sanken. Here, it is a little unusual that only strictly selected NPN types are used instead of the usual complementary transistors. This is a conscious decision of the designer and is one of the reasons for the outstanding Monoblock sound.
![The preamplifier consists of the case with the audio circuits and the three-part power supply (below)]()
The preamplifiers power supplies are as complex as the power supply of the power amplifier. Each of the power supplies, which feed the audio circuits, consists of a toroidal transformer and 120,000 Mikrofarad filtering capacity. This is followed – again channel separated – by the highlight, a battery power supply with rechargeable lead-gel batteries. These batteries have sufficient capacity for around 15 to 20 hours of listening pleasure in pure battery operation, before they automatically recharge. During battery operation there is no connection to the mains voltage and in theory, the mains power cable could even be disconnected. From the batteries we then move to the audio circuits in the upper case. Here, 4-pole capacitors from Mundorf take care of the further filtering and decoupling, before we finally move to the discretely built linear regulators that sit on the audio circuit boards. With this concept, Jiri Nemec takes account of the fact that batteries directly on the audio circuits with no further measures, by no means guarantee outstanding sound.
![The preamplifier features five Cinch, four XLR and one phono input.]()
All audio circuits in the preamplifier are simple and discrete. The topology is similar to that of the power amplifier: differential input amplifier with JFETs and voltage amplifier stage with MOSFETs. The output power amplifier with bipolar transistors of course works in pure Class-A operation and has a very low output impedance of 25 Ohms. For the true balanced operation, per channel two of these amplifier circuits are used, so that the result is an output impedance of 50 Ohms. The volume attenuation is built with relays, which can be controlled digitally and shift precision resistors from Vishay Dale. Good sound does not only involve clever circuitry concepts, but also outstanding parts. Here BlockAudio does not compromise: In the power amplifier as well as in the preamplifier, only highest quality parts are used. Equally important is the mechanical build-up of the devices for which the influence on the sound is often underestimated. Jiri Nemec follows the concept to keep the audio signal path as short as possible and to completely forego cable connections. The case itself has the quality of a vault. How far attention to detail can be taken, is seen in the preamplifier: the vertical circuit boards with the volume control and the 4-pole capacitors are coupled to the case through a communal T-piece, in order to inhibit vibrations.”
![The display can be switched off and shows input and level or alternatively…]()
My highly positive impression of the outer appearance and the concept of BlockAudio thus coincides with Roland Dietl‘s assessment of the circuitry and the consequent implementation and design, with well dimensioned parts of highest quality. But decisive is only what happens in the listening room and this is where Jiri Nemec and Dan Oudes kindly built-up their amplifiers after a longer day in the photo studio. The fact that the listening room was occupied still by Einstein's partially active “The Pure” which impeded a truly meaningful assessment of their amplifiers’ bass range, did not irritate them at all: they did not need to hear their amplifiers within my chain to be a hundred percent sure that they would be convincing in my listening room. And with this they were a hundred percent right! On the Melco HDD player, I rediscovered a wonderful album of the great bass player Christian McBride: Gettin' To It. The first track ‘In A Hurry’ deserves its name. One con arco phrase played on the contrabass in rapid tempo is followed by a short sequence of the entire band with three brass players. As I was not overly careful when choosing the volume, the energy of the brass gave me a jerk. It is however not the average level that is responsible for the live character of the musical spectacle. It is rather the unbridled power, which causes single tones of the trumpet solo to stand out and make the playback exceptionally thrilling. The BlockAudios seem to provide the power necessary for the dynamic peaks seamlessly and without limits. No, I cannot remember ever hearing this song in such a fast, thrilling and dynamic. way..
![… also the operating mode and temperatures of the power transistors, the phase position, the balance settings, the level alignment of the active input and the charge level of the battery supply]()
The next track ‘Splanky’, the come-together of three bass stars, is another reason for untenable infatuation – and this said by a rather stoic Westphalian: In this piece, next to Christian McBride you can also hear Milt Hinton and Ray Brown. The swinging trio turns the Neal Hefti’s composition into an extraordinary experience to which of course, the “Kawero! Classic” and the BlockAudios contribute to a great extent: The power amps control the bass drivers of the “Classic” rigidly and I am positively reminded of the fantastic bass playback of Einstein's partially active 'The Pure”: No other amplifier ever before has been able to get so many timbres and so much melody out of the – nota bene passive – “Classic”. The way in which the chain transfers the groove of these virtuosos on the thick strings is simply dreamlike! Even if I am pretty sure that even 20 years ago almost no productions were made fully passing on limiters and compressors, this disc, respectively its data, sounds exactly like that: dynamic and completely uncompressed! The brass players dazzle, the bass is driving, the piano comes with pressure and the percussion metal has the right bite.
![The menu for the configuration of the phono stage]()
The fact that power stations with a high damping factor have an easy game with speakers like “Kawero!” in terms of dynamic and bass accuracy, can be assumed – not though that the BlockAudios operate with such a joy of playing. At negative feedback and high damping factor, especially the tube-affine audiophiles easily suspect small deficits in the upper mid-range or high-frequency area. For this reason, I leave the levels unchanged and switch to Keith Jarret’s The Köln Concert, which alone to the rather low quality of the instrument, tends to seem strident and annoying when the chain is not a hundred percent in tune. But for the BlockAudios nothing negative can be said: Even at high volume the sound does not tip over but stays open, smooth and spacious. At many previous combinations the desire to turn down the volume came up already at low levels. However, not with the BlockAudios: Even when it gets loud, the tonal balance is perfect and in the treble there is not even the slightest roughness. The piano is large on stage, sometimes delicate and then full of strength: a sensual experience.
No test without going to the monastery, respectively the one from Noirlac with its reverberant refectory, in which Michael Godard likes to record with his colleagues: Of course with the BlockAudios too, the speaker during the ‘Improvisation’ of Patrice Heral cannot be located. A wide room opens in front of me in which drumbeats fade away into the distance. The illusion has best 3D quality. Even in the upper registers the percussion instruments are reproduced delicately and fine. At the end Arild Andersen’s ‘If You Look’ confirms that the treble range of the BlockAudios does not show the slightest trace of coolness or being too analytic. Here, fine art and attention to detail are combined beautifully with colourfulness and smoothness. No, I will not again express my tributes to the power of the drums!
![The audio circuit board of one channel with the amplifier for the in-phase and inverted signal]()
Up to now I have only used the balanced inputs of the preamplifier to process either the signals of the converter or those of the balanced phono stage. Now I connect the signal from the turntable to the Cinch sockets of the phono input, and since a long time ago play the Berlioz' Symphonie Fantastique as Stereo Laboratory reissue of the London Classics: The orchestra in widescreen format to me is a small sensation, the stage has depth and the dynamic is simply fantastic. What should Einstein’s The Turntable's Choice phono stage do better here? The two fully symmetric mono phono preamplifiers enchant with a delicate differentiation, an even deeper stage and more and warmer timbres, however they are listed with a price of almost 10,000 Euro. Nevertheless: The phono part of the BlockAudio dynamically acts even more striking.
![The Mundorf El-Caps and circuit boards with the volume control are also dampened through the case thanks to this construction]()
STATEMENT
The amplifier combination from BlockAudio is perfectly manufactured, using extremely high-quality parts, sounds outstanding and thus can be termed as inexpensive in the best sense of words. And then this punch in the bass! To me the BlockAudios already are the amplifier discovery of the year.
|
Tape recorder |
Studer A80 |
Turntable |
Brinkmann LaGrange with tube power supply |
Tone arm |
Thales Simplicity, AMG 12JT Turbo, Einstein The Tonearm |
Cartridges |
Lyra Olympos und Etna, Einstein The Pickup |
Phono preamp |
Einstein The Turntable‘s Choice (balanced) |
NAS |
Melco HA-N1ZH60, WDMyCloud |
Streaming Bridge |
Auralic Aries Femto plus SBooster BOTW P&P Eco |
D/A Converter |
Chord DAVE |
Preamplifier |
Einstein The Preamp |
Power amplifier |
Ayon Epsilon with KT150, Eintein The Poweramp |
Loudspeakers |
Kaiser Acoustics Kawero! Classic |
Cables |
HMS Gran Finale Jubilee, Swiss Cables Reference Plus, Goebel High End Lacorde, Habst Ultra III, Audioquest Diamond and Carbon,Cardas Audio Clear Network |
Accessories |
PS Audio Power Regenerator P5, Clearaudio Matrix, Sun bar, Audioplan Powerstar, HMS wall mounted connectors, Acapella bases, Acoustic System feet and resonators, Artesania Audio Exoteryc, Harmonix Real Focus, Room Tuning Disks, Tuning Tips and TU-666M, Audio Exklusiv Silentplugs |
![The two battery power supplies for the audio circuits and in between the power supply for the control and digital electronics]()
|
Distortion |
THD+N <0.0005 %, IMD <0.0007 % (at 6 Vrms out) |
Frequency Response |
DC - 300 kHz -0.5 dB, DC - 20 kHz -0.01 dB |
Signal/Noise Ratio |
>130 dB A-weighted, >128 dB unweighted (related to full output) |
Channel Separation |
Infinite (>130 dB) |
Max. Voltage Gain |
+12 dB balanced, +18 dB unbalanced |
Input Impedance |
40 kΩ balanced, 20 kΩ unbalanced |
Output Impedance |
50 Ω balanced, 25 Ω unbalanced |
Maximum Output Voltage |
20 Vrms balanced, 10 Vrms unbalanced |
Inputs |
4 balanced (XLR) pairs, 5 unbalanced (RCA) pairs, Phono Input 1 unbalanced (RCA) pair |
Outputs |
2 balanced (XLR) pairs, 2 unbalanced (RCA) pairs, Phones Output 3 pole XLR receptacle and 6.35 mm / ¼" stereo jack |
Battery Operation Time |
>15 hours |
System Remote Control |
Yes*, Neutrik RJ45 |
Power Consumption |
150 W max. at charging, 50 W at idle, <0.5 W in Standby |
Mains Voltage |
230 / 115 V AC ±10 %, 50 / 60 Hz (factory pre-configured) |
Dimensions |
LINE/POWER 460(w) × 105(h) × 360(d) mm, 18.1(w) × 4.1(h) × 14.2(d) inch |
Weight in total |
28 kg / 62 lbs., ~40 kg / 88 lbs. shipping |
Price |
30,000 Euro |
![Rotated for the photo: In reality, the two transformers for the supply of the audio circuit boards are mounted hanging over damping elements on top of the case.]()
|
Continuous RMS Output Power |
500 W into 4 Ω, 250 W into 8 Ω, up to 200 W Class-A |
Distortion |
THD+N <0.01 % at rated power, min. 0.002 %, IMD <0.003 %, TIM <0.005 % |
Frequency Response |
DC-300kHz ± 3dB, DC-20kHz ±0.01dB |
Signal/Noise Ratio |
120 dB A-weighted, 117 dB unweighted (related to rated power) |
Damping Factor at 8 Ω |
>5.000, DC-20kHz |
Voltage Gain |
+26 dB or +20 dB user-selectable |
Input Sensitivity |
2.25 Vrms at +26 dB gain |
Input Impedance |
20 kΩ balanced, 10 kΩ unbalanced |
Inputs |
1 balanced (XLR), 1 unbalanced (RCA) |
Outputs |
2 pairs binding posts |
System Remote Control |
Yes*, Neutrik RJ45 |
Power Consumption |
1200 W max., 500 W at idle, 50 W at idle ECO mode, 0 W in Standby |
Mains Voltage |
230 / 115 V AC ±10 %, 50 - 60 Hz (factory pre-configured) |
Dimensions |
500(w) × 280(h) × 535(d) mm, 19.7(w) × 11.0(h) × 21.0(d) inch |
Weight |
90 kg / 198 lbs., ~110 kg / 240 lbs. shipping |
Price per pair |
40,000 Euro |
|
Address |
Vodární 1179/1A 779 00 Olomouc Czech Republic |
Phone |
+420 604 514 282 |
Email |
ms@blockaudio.com |
Web |
www.blockaudio.com |