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Dubiel Accoustic

Price : 10 500 zł

Manufacturer: Zakład Usług Elektronicznych "SKORPION"

Bogusław Dubiel
ul. Cicha 6 | 45-824 Opole | Polska | tel.: 77 474 64 06



Country of origin: Poland

Text: Wojciech Pacuła
Photographs: Wojciech Pacuła

Published on: March 1. 2012, No. 95

Dubiel Accoustic is a brand name owned by Zakład Usług Elektronicznych "SKORPION", a company renown mostly for their amplifiers called Skorpion, or Black Horse. The latter was a logo placed on their most famous product, headphone amplifier OTL HV-1, based on 6080 tubes. I used it for almost a year and highly appreciated its performance as did Steven R. Rochlin who reviewed it in 2003 for „” HERE. I listened to it a couple of years ago but I kept its wooden box until today, storing there different things.
I met the founder, owner and chief designer – Mr. Bogusław Dubiel – more than 10 years ago, when I still worked for „Sound and Vision” magazine – it was then that we bought the above mentioned headphone amp as our reference device. I have to say that Mr. Dubiel hasn't changed much since then. He still talks a lot and fast like he was afraid that there was not enough time to say everything he wanted to. But to be honest he has a lot to share as his experience in audio designing and manufacturing is extensive. The company was founded in 1979, and Mr. Dubiel had gathered his personal experience since 1969, when he had created his first phonostage based on ECL86 tube. As one can read on the webpage: „later we built several amplifiers for musicians (mostly guitar amps). Our amps were used for example by Stefan Machel from TSA or musicians of BIG CYC.”

Many years passed since then, lots changed in the audio world. During that period new audio formats were born and died, the audio world was analogue but is digital now. It looks like today Mr. Dubiel would rather find a customer for a phonostage than for solid-state amplifier. He stayed faithful to tubes anyway. Interestingly during the time from company's foundation till today Compact Disc format entered the market and now it is already almost obsolete, and right now Skorpion, under Dubiel Accoustics brand, decided to present their first ever CD Player, claiming that after so many years they finally knew what was wrong with this format…
Mr. Dubiel decided to simplify the design as much as possible. He started with components not effecting sound directly – he used a very simple 4 digit LED display, as it introduces least noise to the circuit. He gave up on drawer – lot of mechanical, potentially resonant, parts were gone this way. In fact a top-loader, and the Nirvana is one, is much simpler design than any other with a classic drawer.
There is a NOS transport mechanism – Philips CDM-2. There are still a lot of these available on the market nowadays; these are cheap but quite durable ones. Mr. Dubiel first tried a CDM-1, but finally chose almost identical CDM-2 because of less resonant material (composite) it was made of. What's more, the laser used in CDM-2 is exactly the same as used in later produced models so it is easy to buy one if replacement is needed. Another advantage of CDM-2 is a good, linear motor (models manufactured later had other motors). Signal from transport goes via I2S link directly to D/A converter. DAC chip is also of NOS type – 16 bit Philips TDA1541. The SAA digital filter installed (in standard) between transport and DAC was removed. So it is a non-oversampling (oversampling=1) DAC without digital filtering. Then we have quite a modern solution – nowadays we know that it was jitter that was responsible mostly for this „digital signature” of the sound of CD Players. So Mr. Dubiel designed a special clock circuit based on Clapp oscillator design. Decoded signal goes next to the two stage output and analogue filter. It is not a typical one as it's based on direct heated tubes. There is a small 1AD4 triode soldered directly to PCB in input and 3Q4 penthode working in triode mode in output. Power supply for tubes is also tube based with Siemens EZ80 rectifier. There is no capacitor in signal path between DAC chip and tubes, and there is one only in the output stage.
As you can see it's quite an original design. It is intentionally anachronistic, but also the most up-to-date knowledge was involved – precise clock on the one hand and tubes on the other, also vibration dampening was treated with utmost care.


Recordings used during test (selection):

  • Live&Swingin’. The Ultimate Rat Pack Collection, Reprise Records, 37362, CD+DVD (2003).
  • Anita O’Day, All The Sad Young Man, Verve Music Group [Japan], POCJ-2761, Original Collection 50, CD (2001).
  • Assemblage 23, Compass, Accession Records/Irond, 10-1674, CD (2010).
  • Diorama, Her Liquid Arms, Accesion Records/Irond, 04-585, CD (2004).
  • Genesis, ABACAB, Virgin/EMI, 51832, SACD/CD + DVD (2007).
  • Jim Hall Trio, Blues On The Rocks, Gambit Records, 69207, CD (2005).
  • Pat Metheny, What’s It All About, Nonesuch Records/Warner Music Japan, WPCR-14176, CD (2011);
  • Paul McCartney, Kisses On The Bottom, Universal International [Japan], UCCO-3038, SHM-CD (2012).
  • Pet Shop Boys, Format, Parlophone/EMI Records, 55716, 2 x CD (2012).
  • Pink Floyd, The Wall, EMI Records/EMI Music Japan, TOCP-71142-43, 2 x CD (2011).
  • The Oscar Peterson Trio, On The Town, Verve Music Group, 543 834-2, Master Edition, CD (2001).

Japanese version available at CD Japan

You don't have to spend too much time with this player to realize what its creator’s intention was sonic-wise, why he believes that the whole digital audio technique went the wrong way all along. But to understand how all the components fit together, how they influence what we hear – that takes much more time. Especially that Nirvana's sound is different from what we are used to hear from digital devices – so different that we have to „accommodate” much longer to it. There are no clear distinctions like bright-warm, dynamic-lacking dynamics, strong bass-no bass you could use to describe its sound. It is all just different than other players manufactured nowadays.

How you perceive the sound of this device will depend mostly on your expectations towards how music should sound in your room. Because the Nirvana offers a warm sound, really warm I would say; its tonal balance is a bit lower too, with some emphasis around 100 Hz. The result is dense, rich sound. It is similar in character to what GrajEnd GrajPudła Numer Trzy delivered. And it is not about „old technologies” used for both devices but rather about similar approach to how music should sound like.
Mr. Dubiel's player sounds a lot like a turntable. The focus is on the midrange, as the phantom images in this part of range are most precisely, distinctly shown, and the sound is, as already mentioned, warm. But these are not the only similarities. The way of presentation is similar too. Tonality makes listeners „stay focused” on sound, and very rich textures of cymbals, trumpets and other instruments playing in upper part of the range, give impression of a very natural, rich sound. And I mean „rich” and not „highly detailed” even though some might describe detailed sound as „rich”, but it is not the same thing. “Detailed” is more about particular device being able to show fast attack but this attack would also have its proper weight. When comparing every aspect of the sound of the rewiewed player with the most precise sounding competitors I know, the Nirvana might, by comparison, seem to sound a bit „dull”, with the attack phase showed not so well as the other players do.
But it is not really true. I think that this CD player is capable of delivering the sound of all instruments at once, so well integrated that it does not need to „polish” the sound of each of them separately to reproduce recording in a very good way. You can listen to any recording, any recording at all – it might be Pet Shop Boys Format, or Jim Hall Trio Blues On The Rocks, and you will understand what I meant – there will be no analyzing, no evaluating of particular aspects of sound – just music, pure, natural sound.

Same goes for the midrange. Voices are rich, slightly colored as there is some emphasis in the low midrange. Especially that its upper part, the one that usually gives a headache to many users with its „digital harshness”, brightness and so on, is in fact tad rolled off and also warm. So no recording sounds bright. It really sounds a lot like a good turntable. But the attack appears somehow hardened somewhere above 2-3 kHz. It is not much, level-wise, and you might even miss it, but since it has its influence on the sound by decreasing differentiation, I have to mention it. It is not a mistake the designer did, it is his deliberate choice (or a consequence of some choices he made for his design rather than trying to achieve particular sound signature/character). If you decide to get rid of digital filters, and use only analogue filter for the range above the Nyquist frequency (for CD it's 22,05 kHz), you have to set the low-pass filter lower than usually plus you can't get rid of high-frequency distortions appearing in the audible range. I don't know how it is done in the Nirvana, but the audible effects are as described above. It's a part of a „price” you pay for eliminating one of the sound processing stages in CD Player.
This „hardening” of the attack is not easy to notice so it doesn't also „disturb” listening in any way. In blind listening test you might say you listened to a turntable (I know – it's a third time already when I compare the Nirvana to a record spinner – I can't help it, and neither will you, once you give this player a try) and that it sounds very smooth in an „analogue” way. Each instrument has its depth, it is shown as 3D object, their sound is lively, breathing which makes it „natural” or simply... „normal”.

And the bass range. OK, I lack some consequence – I said it wasn't a typical sound so there was no use to analyze each subrange and now I do just that – describe treble, midrange and bass. The reason is quite simple – I try to use same methodology for each review to make them, to some extend, comparable. I also don't want this text to be just an expression of my impressions hence the standard analyze of all sub-ranges.

This dichotomy of the sound (it being at the same time organic and coherent) plus the possibility to describe different aspects of it will become clear to you once you've listened to this player yourselves. I can't avoid discussing aspects of the sound that, because of designers choices, are worse than those offered by more „modern” designs. One of them is bass range presentation. Maybe you remember my editorial from Jan 2012 (No. 93) (HERE) where I mentioned that when using my Leben CS-300 [Custom Version] as headphone amplifier I often used „Bass Boost” switch, that added 3 dB at 30 Hz. Just to remind you – I didn't think it was a perfect solution, it did not work with every recording well, but in general it turned out to be quite useful.
At the beginning of this test I listened to the Nirvana using my headphone system (including the Leben). And I always had this „Bass Boost” on, not because the Polish player lacked bass – not at all, it was rich, well saturated, but it was not too well differentiated – it always sounded alike. That's why I could leave the switch on regardless of what music I was listening to. Nirvana's bass was also not so well extended, but I didn't really care.
That's important for you to get the right picture – low tones have tendency to sound alike. Pat Metheny’s guitar had very clear, distinct bottom still, but Jim Hall's bass sounded much alike any other bass. Also deep, electronic bass from Assemblage 23 recording was almost identical to the one from Diorama piece.

So how could I even enjoy listening to this device? Well, because it so easily got me forget about any downsides of its presentation. It dragged me into the music, got under my skin. Sound was incredibly natural and „normal”. No brightness, no harshness that pushed away many music lovers from digital sources. I would even risk a theory that if first digital players had sounded like this one back in 1985, today digital sound reproduction would have been on totally different level than it actually is. Only during the last 2-3 years some very expensive players reached similar sonic effects adding to it much better resolution and definition that the Nirvana lacks. But it offers very good, warm sound. I can see lots of similarities in players at 20 000 PLN and more price mark, and there are some things, like incredible ease of music flow, that are very scarce even among very expensive contenders.

In general the listener is offered an irresistible sound, and even when he realizes after some time what the weaknesses of this device are, some of them caused by designers choices, he might still want to keep that wonderful sound of the Nirvana.
Sure, you might get better resolution, differentiation and even spacing at this price level. But after all when you notice how rich, coherent, lively sound you get you will realize that together these elements give you much more than expected. Something... analogue.

The Nirvana is made in very limited batches by a very small manufacturer. That gives a potential customer a chance to customize his player.
Mr. Dubiel offers some options already and some more should come in near future. Customer can choose color of the front back-lit, and of the display – the latter might be green or red. It is possible to use a couple of different tube types in the output stage. The discs you put under spikes are made of aluminum but it is possible to order ones made of crystal (similar to the ones made by Acoustic Revive). But those made by Dubiel Accoustics are quite inexpensive – the customer has to pay only 360 PLB for 4 pcs, or 300 PLN for 3. You can also order a power cord made of exactly the same wire that is used for inside cabling. Then the whole cabling from the transformer to the plug is the same. Soon there will be an option available with battery power supply. Tubes on board of the Nirvana use very low anode voltage so battery power supply won't be a problem. Mr. Dubiel is in a process of testing different batteries.

Review methodology
I put the player on the Acoustic Revive RAF-48 platform, and it was placed on the top shelf of my Base rack. The rack is placed (unfortunately) between the speakers – I don't have enough space in my listening room to place it otherwise. At the beginning of the review I used standard aluminum discs under spikes but then changed them for crystal ones. Using them made sound more distinct, with better selectivity, but as rich, saturated as with aluminum discs. I would also recommend trying to play the CD Player with the transport lid opened. To load discs you only need to push the button so try listening with the lid opened and closed to achieve different sound and then decide which you like better. I did an A-B test, with A and B known. Music samples were 2 minutes long. I used my Ancient Audio Lektor Air V-edition player as my reference but also the Popcorn A300 with the Music Hall dac15.2 and the Transrotor ZET3 turntable with two motors and 12” SME 312 tonearm.


The Nirvana is a top-loader Compact Disc Player made by Dubiel Accoustics. There is no classic drawer and you put the CD directly on motors axis. You have to place a wooden disc on the CD with an aluminum element attached to interact with the magnet placed under the CD – in that way two elements attract keeping CD steadily in place. The chamber with the CD in it has am acrylic lid that moves along brass rails. It does not work as smooth as in other high-end devices but it doesn't cause any problem to the user either. I received a temporary remote control – the final version will be made of wood. It is equipped only with basic controls.

Front and back
Front panel is a very simple one. There is a 4 digit LED display placed centrally. It delivers information on track number and index (!) or time. There are 3 red LEDs placed below display indicating the mode of display's operation. After each CD change displays goes back to showing track number. Third LED indicates that a „pause” is in use. There are 8 controls button, all red back-lit. There is another LED in infrared receiver that blinks each time any button on remote control is pushed. On the back there is a pair of really nice, solid RCA sockets, IEC and mechanical on/off switch with a red light.

Looking at Mr. Dubiel's work you can tell at once that it is handcrafted, and not something mechanically manufactured in hundreds. And it is not because you can tell by the build or finish quality – quite on the contrary – this player is really nicely done and finished, especially as for a product manufactured in small numbers. It's more about external design, that is characteristic for this company's products and not everybody has to like it. Three sides (front, back and top) are made of chrome-nickel polished, non-magnetic metal plates. Front is painted with black paint with some golden ornaments. There are four cut-outs in the top panel, plus some long slots that prevent tubes from overheating.
Designer paid particular attention to resonance elimination/control. The casing of the device is impressively rigid – metal sheets are thick – but to make sure the designer added a yellow dolomite slate at the bottom of the Player. It is quarried in Poland only in one place – Sławniowice – close to the Czech border, which allows to bring more than just stone from trips to that place (another thing is great Czech beer). Similar base you will find in Audionet players. Using only stone for CD players is a bit risky – stone could over-damp the sound. So here apart from the stone slate there is also a plywood plate with three spikes (two in front and one in the back). The spikes sit in aluminum discs.

Inside there are a lot of cables, some PCBs, great transport mechanism and some good quality components. Transport mechanism is the Philips CDM-2 with a servo board mounted underneath. The mechanism sits on springs and those on rubber washers. They put rubber sleeves over springs to dampen lateral movements. This solution reminded me a suspension system used in Avids' turntables (HERE). Next to the mechanism there a control board and power supply. The DAC chip used is a 16-bit non-oversampling Philips TDA1541s. Next to it sit precise ERO capacitors that make up an I/U converter plus a low-pass filter.
Above the main board there is another holding a precise clock circuit based on Clapp oscillator design.
At the side there is another PCB with output stage. In fact it is a two-stage circuit based around direct heated tubes - small 1AD4 triode soldered directly to the PCB in input and 3Q4 pentode working as triode in output stage. It is an amplifier and a buffer working in single-ended class A with no negative feedback. The output voltage depends on particular tubes used and it reaches 2,3 V up to 4,3 V (rms).
There are damping rings put on all tubes. Next to the tubes there are nice, large oil capacitors working in output stage – Mr. Dubiel says these are Jensens but with non-standard capacities. All resistors are of ultra-precise, metalized type. Since the designer decided to use directly heated tubes, voltage has to be perfectly regulated for them. The rectification is also done by tube - Siemens EZ80 to be specific. Next to it there is a large toroidal transformer with a couple of secondary windings, and large NOS filtering capacitors.
The cabling inside is a high purity LGC copper in Teflon sleeving that is originally manufactured for NASA. Mr. Dubiel buys leftovers from them as that's the only form available for outside buyers.

Everything looks just great! Respect! One would not expect such a high quality components in a device at this price level.


  • CD player: Ancient Audio Lektor Air V-edition, review HERE
  • Phono preamplifier: RCM Audio Sensor Prelude IC, review HERE
  • Cartridges: Miyajima Laboratory SHILABE, review HERE), Miyajima Laboratory KANSUI, review HERE
  • Preamplifier: Ayon Audio Polaris III [Signature Version] with Re-generator Power Supply
  • Power amplifier: Soulution 710
  • Integrated amplifier/headphone amplifier: Leben CS300 XS Custom Version, review HERE
  • Loudspeakers: Harbeth M40.1 Domestic, review HERE
  • Headphones: Sennheiser HD800, AKG K701, Ultrasone PROLine 2500, Beyerdynamic DT-990 Pro; 600 Ω version, review HERE, HERE, and HERE
  • Interconnect: CD-preamp: Acrolink Mexcel 7N-DA6300 (article HERE, preamp-power amp: Acrolink 8N-A2080III Evo, review HERE
  • Speaker cable: Tara Labs Omega Onyx, review HERE
  • Power cables AC (all equipment): Acrolink Mexcel 7N-PC9300
  • Power strip: Acoustic Revive RTP-4eu ULTIMATE
  • Stand: Base; under all components
  • Resonance control: Finite Elemente Ceraball under the CD, Audio Revive RAF-48 platform under the CD and preamplifier
  • Pro Audio Bono platform under Leben CS300