For over a hundred years the recorded arts have been tightly connected to and restricted by physical media and delivery formats. To obtain and enjoy a relatively high quality version of a musical performance, one had to turn to either a Vinyl record or a Compact Disc, and more recently to Super Audio CD and BLU-RAY disc. These formats have their limits however, both in bandwidth and maximum playing length and almost never can harbor the recording in its original quality.

The master recording compared to the delivery format…

The Spirit of Turtle has been producing all projects, from approximately the mid nineties of the last century and onwards, in a higher recording format than the traditional CD and later SACD. We recorded the first 192kS/s-24 production ever, soon complemented with DSD simultaneously in the workflow, and many productions do exist as such in our archive. From 2005 onwards all our work is frozen in the bits with 352,8kS/s-24bit (DXD). Also many recordings are produced in immersive surround, of which only several where released as such for the mainstream market at the time. Even SACD stayed a niche for many years, so few people had acces to the actual product as it was intended by the artists and producers. Most of our productions only reached the consumers as stereo in a relatively “low” resolution digital format.

dCS-Vivaldi-DAC_Front1NADAC-FrontRight2-White-Shadow

dCS Vivaldi                                                             Merging Technologies NADAC

No more limitations by physical media…

Now all that is changing rapidly with the possibility of downloading audio files and playing them with highly flexible and ergonomically clever designed media players. In essence one only needs a decent PC and a relatively modern Digital to Analogue converter, with either USB and/or Ethernet I/O, to playback original master files in a wide range of formats. Of course, as always, quality also counts for this playback chain, but at least the possibilities are not restricted by a physical medium anymore, so everybody can have acces to the actual source of great recordings.

Instrumental in the development of digital converters…

The Spirit of Turtle staff have played an instrumental role for already longer then 25 years in the development and implementation of professional audio gear and digital converters in particular. We are long time consulting partners of Data Conversion Systems (UK) and Merging Technologies (SUI) and have been working on several professional and consumer converter models by both companies. Our workflow contains also dozens of units of both brands and we consider them as leading in the field because of their impeccable temporal response and natural timbral quality. For many years we have been distributing professional dCS gear on the mainland of Europe and from the summer of 2015 we are distributing NADAC by Merging Technologies in the Benelux. Both companies always have been close to each other with highly complementing products in professional audio and mutual respect.

Straight from our studio into your own living room…

We believe that, because we so extensively use these products in our workflow, dCS and Merging Technologies converters communicate our artistic craft the best by far and when you listen to our recordings through these units, you essentially can hear the same quality as we experience in the studio. This is rather special, seen the fact that for many years a master recording was quite distant from what the consumer would perceive in the living room. Now with NADAC and dCS converters you can have the music straight from our studio into your own living room in full immersive High Resolution quality!


Jaap van Zweden & The Spirit of Turtle

The Spirit of Turtle wants to congratulate Jaap van Zweden with his appointment as musical director of the renowned New York Philharmonic Orchestra! For many years we have been working together with the maestro, both at the Netherlands Radio Philharmonic Orchestra and The Dallas Symphony Orchestra in Texas USA and we have several fantastic productions with him directing in our catalogue, available as Hybrid SACD and High Resolution Download.

Album of the Month February, Bruckners 6th Symphony 25% discount

 The Netherlands Radio Philharmonic Orchestra/Jaap van Zweden / Bruckner Symphony NO.6

To celebrate this fantastic news and incredible achievement we are offering all our titles with Jaap van Zweden for 10% discount and Bruckners 6th Symphony as a 25% discount. We trust you will be as thrilled about these performances as we are and we wish Jaap van Zweden all the best for his new adventures to come. The Spirit will always be in close range with Jaap van Zweden so we are heading for an exciting future!


This month, we’re in the winter season holiday Spirit!

What better than enjoying your favorite music, triggering dear memories from the past, and adding new music to your palette to create new memories for the future?

When it’s too dark and cold to be outdoors, snugging around the fire with a good glas of wine enjoying music recordings in the highest quality, by artists who have the ultimate gift to communicate their message through the timeless music of all the ages, past, present and future.

An abundance of titles with these qualities are available on our Spirit of Turtle platform which we would like you to discover, so during this holiday season, ending January 6th 2016, we are offering all our products with a 10% discount! Simply use the discount code “ hohoho ” at checkout and enjoy!

Click here to visit our Store!

May the Spirit be with you!
Bert and Brendon


Review for Bruckner: Symphony 1

“The Netherlands Radio Philharmonic Orchestra under conductor Jaap van Zweden is running through a Bruckner symphony cycle. Bruckner is ‘on trend’ at the moment and a lot of people are running through his works, some good, some not so good. What makes this so special?

First, this is the original ‘Linz’ scoring from 1866, rather than the later ‘Vienna’ version from 1890, and it sounds more authentic as a result.

Second, although this cycle is a bit mixed, Van Zweden seems more comfortable with the earlier Bruckner symphonies. He summons up more of the ‘saucy maid’ Bruckner (‘saucy maid’ is the nickname Bruckner gave to this symphony) than the more monumental works later in his career.

However, the big bonus here is the sound quality, regardless of whether used in multichannel or stereo, SACD, or simply CD.

However, the big bonus here is the sound quality, regardless of whether used in multichannel or stereo, SACD, or simply CD. It’s a truly sublime recording, at once detailed, spacious, and clean. There is a strong sense of ambient information, sweeping orchestral moments, and plenty of dynamic range on show, too.

Classical music doesn’t get anything like the kind of airplay it should receive today, even at hi-fi shows. Which is a shame because this is truly demonstration quality sound.”

– HiFi+ (UK)


Ever since the first time we had the chance to make a recording in the Altomontesaal of this high baroque style Stift in the neighbourhood of Linz, the main city of Oberösterreich, we have been extremely happy with the acoustics of this room. At the time Bert stood there with open eyes but even more open ears, and was stunned by the reverberation characteristics of this ceremonial space. An ensemble with eight musicians that sounds like an orchestra, without losing transparency between the individual voices.

It is due to Bert’s knowledge and empathy that this effect translates so convincingly into the recording. We are currently recording for in the fall of 2014 with H.I.F. Biber’s “Sonatae Tam Aris Quam Aulis Servientes”. I am very excited about that and I am sure it won’t be a problem for The Spirit of Turtle to record the ensemble with 2 additional trumpets with radiant clarity…!


After a highly succesful evening at the Northstar Recording Studio, we wanted to offer more people the chance to experience our studio

All of you can enter to win!! Simply write a review on your favorite title on www.spiritofturtle.com. The four best reviewers will receive an invitation to the Spirit of Turtle Experience around June.

As a bonus, every reviewer gets a 50% discount on any download you purchase at The Spirit of Turtle!


“High Resolution Audio”, what do we mean with that?

Like many others in the music and High End audio industry, we at The Spirit of Turtle claim to deliver “High Resolution Audio” recordings. This term might seem straightforward and easy to understand, but in practice it’s used for far too many formats of which several do not always qualify. Because of that, for some people, it has become a rather confusing term, causing many misconceptions amongst non-experts. Therefore, we’d like to explain what we do at The Spirit of Turtle, and why we call our recordings and audio files “High Resolution Audio”.

It might not come as a surprise, but a good recording starts with good musicians, a suitable recording space or studio, impeccable artistic producing, inventive microphone techniques and an optimal implementation of “state of the art” tools like microphones, cables, amplifiers, digital converters and playback monitoring. Also the control room where the recorded material is auditioned and evaluated is incredibly important, as this is the place where the music is frozen into the bits on the tape or Hard Disc. Many decisions made at the time of recording cannot be altered or eliminated afterwards. We at The Spirit of Turtle mostly work with custom tailored tools which perform according to our wishes and specifications developed over more than 25 years of trial and error and this has lead to a highly proprietary facility. Recording tools and microphone techniques that guarantee an optimum in transparency, dynamics and temporal resolution. The source formats we have used and currently use, and their inherent “high resolution”, have always been according to the highest standards at that moment in time, and several ground breaking formats even have been introduced as a worlds first by ourselves in collaboration with hardware manufacturers like Data Conversion Technologies – dCS (UK) and Merging Technologies (CH), companies which have been leading in the field over the past decades.

” All High-Resolution Audio starts with a good recording … “

Please, never believe anybody who will tell you that the delivery format on a physical disc or audio file is responsible for a “good sound”. The format only communicates and/or translates the source material – which cannot be high resolution, if microphones and the other tools further up the line are not dealing properly with the enormous wealth of colors and temporal transients which music consists of.

What we try to explain here is that the format in which a recording is released comes at a rather late stage of the process of bringing the music from the artist towards the audience, and is not and can not be responsible for a good result other than simply allowing for the quality of the performance and recording to become apparent. It is not DSD, DXD or PCM or whatever number attached to it which is responsible for a good recording! A bad recording is still bad in DSD or DXD, it is often even more apparent that it is bad because one hears it better due to the higher “resolution” of the delivery format…

Having said this, the delivery format can certainly take away something from the original quality if the original recording resolution supersedes the delivery resolution. For instance, a recording done in DSD or DXD will not translate 100% to a traditional CD as its resolution is roughly 8 times less in terms of accuracy in the frequency- and time domain. These numbers do count, however a good recording in DXD or DSD is still a good recording on CD…

All recordings we share with you as “High Resolution” audio have been recorded with a sampling frequency of at least 96kS/s (kHz) with a bit depth of 24 bits, but for the majority of the projects with 352,8 kS/s (kHz) at 24 bits, the so-called DXD format. All these recordings are offered in their original format, but ultimately also as DSD. Some have been recorded as so called “Native DSD”, however this format is proven rather unsuitable for several post production processes, which in some cases causes the format to loose its initial advantages as rigid filtering is needed to keep the high frequency noise spectrum within the SACD specification.

”  … the vast majority of our projects [are recorded] with 352.8 kHz at 24 bits … “

Note: It must be stated that many SACD’s on the market are not what they seem, as the productions consist of stacked DSD channels which consist of too much high frequency noise and therefore are “limited” in bandwidth.

Our reason to output all productions in DSD is that playing back through DSD DACs of a DSD stream generated from a PCM source inherently translates the music ever so often better – in our experience – than even the original does, due to more elegant filter characteristics in these DACs and a rather different “jitter” behavior of DSD vs. PCM. Furthermore, a dramatically different response from monitoring equipment to the DSD signal supplied makes that it is perceived as a very musically attractive format. In essence, we believe that in most cases the best playback comes from DSD – for reasons described above.

” … we believe that in most cases the best playback comes from DSD … “

So we decided to offer the 96/24 repertoire also as DSD as the benefits outweigh the fact that the source bandwidth and impulse response are theoretically less optimal than the playback format DSD. The data rate is approximately the same however and our implementation of 96/24 has always been one with gentle filtering which allows for an impulse response and temporal accuracy which suits DSD playback perfectly. This is one exception to our rule that that source material should outweigh the delivery format or at least equal it.

The other exception we’ve experimented with is delivering our DXD source material in the DSD128 and DSD256 format. The reasoning there is that the proprietary filtering we use in many of our DXD recordings has an optimal impulse response with a Gaussian like characteristic. This delivers a very wide pass band characteristic which benefits greatly when played back in a format from the DSD family with far less, by noise shaping induced, correlated noise. The clean frequency response up to 176kHZ of DXD and its elegant filtering deliver a fantastic DSD128/256 stream which in turn benefits from DAC implementations capable of these formats to output. The best of both worlds in our experience!

What is important to consider however is that the term DSD does often stand for many different permutations of the format. How the so called “bitstream” is conceived in the first place differs greatly from one ADC to another and even within the same analogue to digital converter there often are more than 10 different “modulators” to choose from. So again, never be deceived by a “term” or “number” of the format, but listen for yourself and decide which format communicates the musical message best under the circumstances available…

– Bert van der Wolf


Telemann has always been a good friend of mine. Remaining somewhat in the shadow of my other great (and also his!) friend Johann Sebastian Bach, Telemann speaks directly to the heart. So I am very excited that the latest Bach Concentus recording was dedicated once more to this most versatile composer and that we could realize it with Bert van der Wolf, who makes a musical performance really tangible. On the program are 3 orchestral suites illustrating Telemann’s humour and 2 profound oboe concertos (with Vinciane Baudhuin as a remarkably sensitive soloist).

Can’t wait to get my hands on the finished product…!

Warm regards,
– Ewald


A few weeks ago on the Facebook page of Spirit of Turtle a spontaneous request was done to post a selfie with a record of the Spirit of Turtle. The reward was to take part in a competition were the winner(s) were invited for a studio tour at Northstar and a listening session of the masters. As a true music fan and audiophile I have collected many records of the Spirit. Also the collectors box which was introduced last year. Some of the tracks I also use in listening sessions when at work for acoustical projects were high-end installations and listening rooms are involved. I highly appreciate both the recording quality and the jazz & classical music performed by so many skilled musicians. But how do these master tracks sound in the studio were they are created by the skilled and experienced sound engineer Bert van der Wolf?

So I swiftly made the selfie and posted this on FB. The waiting started …. winner or not?

I Was very happy to hear that I was selected amongst two other winners. So Thursday 16-OCT the event really happened!

A warm welcome by Bert and Brendon in the acoustically optimized studio which is really on top high-end level. Very rare in the professional world as Bert stated. Avalon loudspeakers, Spectral mono amplifiers, DCS digital/analog converters. Wow, a high-end shop in itself! As an Avalon owner myself I was very curious to know how the Avalon Eidolon’s sound in the 5.1 environment that Bert has created. The other participants, Joeke, Frits, his father in law, and I changed frequently the sweet spot, actually in the chair of the sound master himself. After pressing the space bar on the Apple workstation the playback started. This was a truly compelling experience, closing my eyes I came in a state of really being at the performance. The used recording technique transports the listener to real event of which as much is possible is “copied” by Bert during the recording. He does not like to filter out life sounds like picking an instrument or the breath intake of a piano player. It is all there on a natural way. Tonal qualities are on reference level. Dynamics are life like. Simply exciting and astonishing to listen to the real masters. The studio transforms in a time machine. Next to listening music, Bert also answered many questions and highlighted some important principles when recording. For instance the importance of the time domain and transients in music. The importance of these aspects are often underestimated.

For the love of music we must be proud that there still are sound engineers who put quality in the first place. There are only a few of them and to be honest many modern recordings do suffer a lot from bad recording and mixing, and by that killing the music.

Many thanks to Bert van der Wolf and Brendon Heinst for giving me the opportunity! Just keep up the excellent work, cheers!

– Ben van Leliveld


When I am asked to describe my enthusiasm for making music recordings, I automatically start talking about the importance of sound and music in my personal and professional life. Music that lives and is played by real musicians on real instruments, and the fantastic and complex effects that their sound waves create in different acoustical environments.

Holographic Music Recordings

To be able to actually capture these unique moments in time, by recording them, and recreate the holographic attributes of traveling sound waves, is mesmerizing in itself, but what makes it an irresistible way of spending my days, is the possibility to retrieve and relive this experience whenever I want at any time in the future. Every recording in itself is like a personal time machine for all involved in a recording production and for me in particular. The playback of a track immediately transports me to the moment of the real musical event and the sound waves that traveled through space in the past present.

To make this experience every time as real and vivid as possible I have searched for tools and techniques that honor and preserve the musical message and the temporal behavior of the sound optimally. I however found that very few standard recording techniques are available that actually result into anything like a real live sound experience. I also noticed that my fascination for this time travel aspect, by reliving the past through accurate recording and holographic reproduction, was not as common in the recording business as one might expect. Al lot of colleagues and even musicians seem to be very occupied with the nature of sound itself, rather than by its effect on the environment and the resulting “immersive experience” in an acoustic environment. It is the connection and placement of sound in the universe surrounding us however which completes a musical intention. Sound itself is rather abstract if one cannot recognize where it comes from…This also can be beautiful, but in most cases with traditional instruments and compositions it is the connection with daily life surrounding us what makes the music communicate. F.i. a french horn sounding from far in the woods or the shimmering daylight presented by soft string sounds, and like the fog above a cold lake…

Essence of Musical Perception

Many recordings also sound like a patchwork of several pictures from a different style of glossy magazines, individually cut out, beautiful in itself, but with different colors and focus on the details. These recordings can sound wonderful, but often leave me with a confusing sense of bewilderment and distraction from the players intentions. An instrument itself is nothing without its player and not sensing the artist playing the instrument in the acoustical environment he or she is in, makes a recording far less engaging than when all is placed according to the rules of physics. Sometimes instruments also sound like projected through a distorting laughing mirror with odd shapes and out of balance colors. Strangely enough many seem to accept these distortions in audio, however in film nobody would want to look at them. Audio and music have a more abstract character than pictures, and only when presented with the optimal clarity, correct balance and spatial location, one seems to understand what is really going on. Our brain needs these details however to distinguish whether a sound is posing a threat, as our hearing is essentially our warning system for danger. The emotions that are triggered by properly defined locations of sound sources, are the essence of our musical perception in my opinion.

Triggering Emotions

Reliving the feeling of being somewhere at a particular moment in time where a sound is produced, rather than listening only to the sound itself, is of great importance to me and defines the essence of The Spirit of Turtle. There is a huge difference to me and getting this aspect right, gives an explanation for the fascinating phenomenon that many so called “demonstration” recordings and live performances communicate the artistic message of musicians much better than often many “professionally produced” recordings. One then can actually hear real life events like noises, responding audiences and small musical and technical mistakes. Sometimes literally the reflection of the walls of the living room of the artist where he or she did put the demo recording down. This is what triggers the brain into being attentive, far more than just sounds with no direction and placement. No matter how long ago a recording like that is made, every listener travels through time immediately to the original event and strongly senses the feel for the moment. Most professional recordings are deliberately made more abstract however with less “real life cues” and a less defined spatial reference. One does hardly hear the environment, the human mistakes or “normal” noises surrounding a musical performance, although particularly the sound waves produced by these details carry a lot of relevant information for triggering an emotional response in the brain of the listener.

Sharing Air Molecules

What I have found is that preserving all of this in a recording is not so simple, because most professional electronic equipment is not sensitive enough to capture the essence of music and sound and keep the spatial cues in tact. On top of that there are traditions and fashions ruling in the recording industry, whereby even the greatest artists are blinded by a strange fascination for technical, horizontal and vertical perfection. Everything in tune and together and instruments preferably fully isolated from each other in an audio mix. This all to achieve the goal of ultimate transparency. In my opinion this is rather unnatural and these artists forget that it is the mixture, blending and also the masking of certain registers in instruments in relation to each other which gives them the unique placement in space and time. Popping out due to natural physical acoustical phenomena or reflections from walls and objects near to them. These cues are of the utmost importance to our brain to distinguish what is going on in the audio information that we detect and thus believe that a real event is taking place in a recording. When musicians rehearse with one another, they always seem to understand this and use the attributes of the (mostly limited) space surrounding them, but strangely enough in recordings they try to eliminate these parameters as much as possible. Ultra dry studio’s, crawling into close microphone set-ups, avoid “bleeding” into other microphones than their own, different synthetic reverb on every instrument and so on. A whole new tradition has evolved around this way of thinking and what is regarded as being the proper way to record is light years apart from what “real” instruments and singers do sound like in real life. There is a huge physical difference though in merging electrons in signal wires and molecules traveling through the air and the results are obvious. That is why layering and over-dubs do work actually. One can make any mix with recording tracks completely separately and layer them, but this also means that there is far less interaction between them. The one is the result of the other. Sharing the air molecules however asked for careful playing and balancing, but result into the most enchanting combination tones and harmonics that cannot be achieved through electrical layering.

Revolution in Recording Techniques

Although there is nothing wrong with this movement or fashion in recording techniques, and it also brought many blessings, I personally have tried to break up this tradition for the past 25 years and find ultimate transparency through better and proper placement of musicians and instruments in a shared acoustical environment. The evolution in electronics and tools with correct tonal and temporal behavior give me the opportunity to create mixes whereby every detail can be found in the “bubble” of sound traveling towards the listener. Not by layering everything separately and present is as separate lines, as if in a “bar-code”, but inviting the listener to step into the ensemble presented and find the individual actors in the play. A more interactive communication between recording and listener if you like. The sharing of the same air molecules by all instruments creates the blend and the musicians automatically adjust. Just like they do when rehearsing and making their first demo recording!!

I have found that this approach is embraced by many musicians and gives them a new sense of inspiration. They even often seem to be surprised how good they actually sound in real life…!

The results over the years have been staggering and many musicians are gradually shifting towards this fundamental different approach, which in itself is nothing new, because it is how man once started to record. In the old days the orchestra gathered around an upside-down bucket and all tried to angle their instruments towards it. Today we have state of the art recording tools which leave almost nothing to wish for in temporal behavior and distortion free electronics, and when cleverly used, these can produce recordings that sound as if one is uplifted and transported to the actual musical event.

This at any time, like in a personal time machine…

– Bert van der Wolf