Recordings Integral Beethoven String Quartets have come to a conclusion!


This was the last stretch.
16 String Quartets and the Grand Fuge in one year!
7 or 8 CD's.
What a monumental production and a life fulfilling privilege and blessing to be part of this!
Vol.1 Op.18 I-VI, highly praised and recommended, already in the store: https://spiritofturtle.com/.../beethoven-early-string...
Vol.2, Op.59 I-III and Op.74, coming up and the last volume anticipated for spring 2025 with Op.95, 127,130, 131, 132, 135 and 133 (Grosse Fuge)
Lot's of great inspiring studio moments to come in the post production of the remaining 6 Quartets.



Coming Up release March 1st

Gauguin Ensemble

Color Soni

Brahms, Zuidam, Zemlinsky

Latest Recordings

 January 11-14 & February 8-11

Narratio Quartet
Beethoven integral String Quartets Volume 2,3&4

Konserthus Stavanger Norway

January 29th-February 2nd

Stavanger Symphony Orchestra | Jan Willem de Vriend

Robert Schumann Complete Symphonies Volume 2


"Bij Andreas", Naarden Vesting, The Netherlands

December 20th

Piano Duo Scholtes & Janssens

Canto Ostinato | Simeon ten Holt (2 Live Concerts)



Concert hall AMARE, The Hague The Netherlands

December 13-17th 2023

Residentie Orchestra The Hague | Anja Bihlmaier | Yeol Eum Son (Piano)

Maurice Ravel Piano Concerto for the left hand



De Bakermat Arnhem The Netherlands

December 7-9 2023

Raaf Hekkema Solo saxophone

25 Caprices & Sonata for Saxophone Sigfrid Karg-Elert


Vila-seca, Tarragona, España

November 27-29 2023

- Lina Tur Bonet | Misica Alchemica.
Antonio Vivaldi & Astor Piazzolla | The 4 seasons.
(Glossa Music)





In the coming period the multiple awarded recordings of the Beethoven Symphonies by Anima Eterna Brugge | Jos van Immerseel will become available in full immersive High Resolution audio on The Spirit of Turtle!

These recordings have been on the market for over 16 years now, but only as stereo CD. Now finally these will be shared with the world in their original full splendor.

  • Here is a superb new set of the most famous symphonies in our musical culture, brilliantly played on period instruments. Jos van Immerseel and his highly skilled Flanders-based orchestra Anima Eterna play at modern pitch (A=440), which they have established was done in Beethoven’s Vienna. As the composer had to make do with motley collections of amateurs and professionals and couldn’t hear a thing after about 1817, this is better than anything he experienced. Van Immerseel’s interpretations are exciting but always musical. (The Observer Daily Mail).


Producers note: "A truly inspiring time travel during the re-mastering process of these legendary performances!" These recordings were one of the first made in DXD after I adopted this format in 2005 (dCS prototype ADC's), still revolutionary in 2006 and most likely one of the first recordings fully processed in 352,8kS/s/24bit! I decided to have another go on the mix for the master files, now 16 years later with the progressive insight about and acquired tools over the years for this stunning high resolution. It was a pleasure to find the hidden gems within these tracks.

Bert van der Wolf-Oude Avenhuis 2023





Due to the discontinuation of Merging Technologies NADAC by Sennheiser, the NADAC design team has initiated a follow up with the new brand Master Fidelity NADAC. A new generation of NADAC products with a revolutionary new design state of the art Network DAC and Master clock units for the ultra High end market. 

For more info see: http://www.master-fidelity.com/

We anticipate to ship the first orders in January 2024.



Latest recordings

October 23-26-2023
Gauguin Ensemble
Brahms | Zemlinsky | Zuidam
July 2-5
Narratio Quartet
Beethoven integral String Quartets Volume 1
June 12-15
Stavanger Symphony Orchestra | Jan Willem de Vriend
Schumann integral symphonies Volume 1



April 25-29
Stavanger Symphony Orchestra | Andris Poga | 

Plamena Mangova (Piano)

Sergei Prokofiev | Romeo & Juliet

Dmitri Shostakovich | Piano concerto NO.2

Alfred Schnittke | Concerto for Piano and String Orchestra


April 16/17 2023

Oscar Verhaar (Counter tenor) | La Sfera Armoniosa /Mike Fentross

"Witte kerkje" | Baarn, The Netherlands
Händel Arias
March 6th-10th 2023
Cappella Pratensis | Sollazzo Ensemble
Den Bosch Choir Books Volume 4
Heusden | Holland
Stratton Bull, Andrew Hallock, Tim Braithwaite – superius
Lior Leibovici – contratenor
Peter De Laurentiis – tenor
Marc Busnel – bassus
Mara Winter – renaissancedwarsfluit
Filipa Meneses – vihuela de arco
Christoph Sommer – luit
Anna Danilevskaia – vihuela de arco
Netherlands Dance Theatre and Ballet Orchestra
"In the Dutch Mountains"
Delta Pianotrio

Lera Auerbach



February 27th - March 1st 2023

Chianti Ensemble

Quintets Korngold and Fauré

Friday February the 3rd

19 beautiful “Love Songs” from late classical Vienna about love, seduction, happiness, passion, drama, pain, faithfulness and unfaithfulness. Written by Joseph Haydn, Mauro Giuliani and composers of the hitherto never recorded Wiener Lied collection (such as Joseph Anton Steffan and Johann Holzer). They are romantically and dreamily sung by lyrical tenor Markus Miesenberger. Markus is sensitively accompanied by Erich Traxler and Christian Haimel on early 19th Century original instruments.This pure and authentic rendition will enchant you and transport you to a historical Vienna you’ve probably never yet heard!


December 2022

No less than 3 HQ|NORTHSTAR / TSoT albums in the Charts of Best Productions of 2022!

Every year, the Dutch newspaper de Volkskrant chooses out of the 1000's of pop, jazz and classical CD releases in a year their Top 40 of BEST albums.

2 productions by HQ|NORTHSTAR / The Spirit of Turtle are awarded this year by featuring in this prestigious list. It is a great joy to find that so many people like what we achieve with these tremendously gifted artists.

Congratulations to Cappella Pratensis and Olivia Vermeulen with Jan Philip Schulze with the respective albums "Apostola apostolorum" | The Den Bosch Choirbooks vol. 3 (NO.37) and "Hello Darkness."(NO.17)



In the other leading Dutch newspaper the NRC, Hannes Minnaar's album "Shostakovich 24 Preludes and Fugues Op.87" is ranked NO.2 (!) in their Top 25 of best Dutch albums of 2022!


December 2022

The Spirit of Turtle is pleased and honored to announce an intense collaboration with Johannes Leertouwer in producing an 8 SACD (research) project for the Seoul National University of Music. We will be recording over the course of 2 years all Beethoven String Quartets on original period instruments with the Narratio Quartet and the Brahms Violin/Piano Sonatas with Johannes and Julian Reynolds.

First releases the end of 2023 on the Challenge Classics / HQ|NORTHSTAR label.

The Narratio Quartet

Johannes Leertouwer / Violin

Julian Reynolds / Piano




Saturday December 3 2022

After 40 years being a couple, raising 3 sons, Bert van der Wolf, co-founder and producer/engineer of The Spirit of Turtle | HQ|NORTHSTAR, married his love Veronique Oude Avenhuis. A truly magical day to celebrate in abundance with those who shaped and changed our life over the past decades.

Bert: "Veronique is my true love, anchor, guru and best friend for life...Now she is also my wife officially and I am proud to carry her name, which will from now on be on all future productions mentioned...Without her, there would be no Spirit of Turtle or anything that has been created through my hands over all these years..."

At the festive diner, 2 greats of the music world met each other for the first time ever, which was a lovely historic moment. Sigiswald Kuijken of La Petite Bande and Jan Willem de Vriend, conductors exceptionele, both regarded as pioneers in their field of musical expertise.

One can only guess what they were chatting about all night...;-)





Interview TSoT 25 years anniversary on FWD





November 18-20

Recordings Simeon Quartet

Canto Ostinato | Simeon ten Holt

Piano's Maene, Ruiselede Belgium




November 7th

Recordings with Trio Kanter

Synagoge The Hague




October 30th 2022

Recordings La Sfera Armoniosa | Mike Fentross

Unico van Wassenaer | 6 Concerti Armonici

Theater De Vest, Alkmaar, The Netherlands


October 28th 2022

Recordings Nederlands Danstheater/Balletorkest

Amare, The Hague, The Netherlands




October 25-27 2022

Turtle Records® Recordings with Raaf Hekkema (Saxophones)

Community Centre De Bakermat, Arnhem, The Netherlands

Bach transcriptions




October 17-20

Turtle Records® Recordings with Ensemble Teun & Teun

Teun Wisse (Recorder), Teun Braken (Cembalo)
Zuidvermaning Church, Zaandijk, The Netherlands
Dutch Masters from the 18th Century
De Fesch, Van Noordt & Van Wassenaer
Release June 2023




October 6 2022


At the Edison Award Ceremony, October 6th 2022, Robert Holl, Hannes Minnaar and Dick de Graaf, all featuring on The Spirit of Turtle platform, won a prestigious Edison Award statue! Hannes for the category solo instrument, with the Goldberg Variations, Robert and Dick for their complete recording oeuvre!!

Get those albums the rest of October 2022 at a 20% discount. Code: EA2022

Congratulations and a well deserved recognition for them and for me many lovely memories of the recording productions with these fantastic artists! Tremendously grateful to have them all featuring on www.spiritofturtle.com

Bert van der Wolf, 07-10-2022

From the jury:

"Minnaar lets the music speak for itself and does not force anything, but still decorates here and there in an interesting way. Everything sounds intelligent, light and flowing and makes perfect sense. Nowhere do you get the idea that Minnaar is imposing his will, as if he has switched off his ego as an interpreter and is only trying to bring Bach's sound and spiritual world to life optimally."

“A tradition that de Graaf knows through and through, passes on to younger generations and, like other key players in the field, continues to nurture innovation. All these qualities, with a record/CD oeuvre that is the result of this, makes him a logical and justified winner of the Edison Jazz Oeuvre Award”

"Music journalists from home and abroad have often described how Robert Holl (75) does not sing, but embodies his material in operas and song recitals. He has a world career as an opera, song and concert singer, reflected in an enormous phonographic oeuvre. Many singers call him a key figure in their own development – ​​whether it was through regular lessons or thanks to one of the many masterclasses that Holl gave and still gives. At the beginning of this year he turned 75 and he still impresses with the intensity of his recitals. Partly for this reason, the jury Edison Klassiek considers it an honor to award Robert Holl the Oeuvre Prize 2022."


September 27-October 1st

Stavanger Symphony Orchestra / Andris Poga / Martin Grubinger

Stavanger concert house

Sergei Rachmaninov Symphony NO.2 , 

Peter Eötvös: Speaking Drums


September 19-21

Recording Residentie Orchestra The Hague / Anja Bihlmaier & Yeol Eum

Maurice Ravel Piano Concerto

Concert Hall Amare The Hague

September 15-18

Recording Markus Miesenberger, Erich Traxler & Christian Haimel

CUPIDO (Love Songs)

ST. Michael Church in ST. Marien / Austria

Wonderful late 18th, early 19th century songs for Tenor, fortepiano and Guitar.

Release on Turtle Records® under license Challenge Classics | HQ|NORTHSTAR

September 9-12

Recording Cappella Pratensis / Missa "Maria Zart" from Jacob Obrecht

Heusden / The Netherlands

Arguably the mass of masses, this massive vocal work by Jacob Obrecht sung by 12 of the most renowned specialist singers one can imagine.

Release next year on the Challenge Classics | HQ|NORTHSTAR label



September 2nd 2022

This amazing box celebrates the 50th anniversary of one of the most influential and seminal Baroque ensembles of the recording history: La Petite Bande and its conductor. The box contains the St. Matthew Passion, the St. John Passion, the Christmas Oratorio and the Mass in b minor. All these works are performed according to the individual and strictly musicologically based criteria elaborated by that great musician who is also a great scholar that goes under the name of Sigiswald Kuijken.

This special edition collection will also be available as download in most formats up to DXD and DSD256 at a special price.

Producers note: The maximum original resolution of the Mass in B Moll is DSD64 & PCM192kHz/24 bit and as such combined with the other variants.

It is a tremendous privilege to collaborate with such an iconic ensemble and its leader already for so many years and I congratulate Sigiswald and all involved with this unbelievable milestone. To be responsible for all the recordings in this collection and many more, in the privileged role of artistic producer and sound engineer, has been a great honor and I treasure countless dear memories from our time together.

Bert van der Wolf

 August 25th



Dear, valued Friend of The Spirit of Turtle,

This morning I had a big scare!

It looked like my platform was taken over by some hostile "Music Aficionado" that found a devious way around the fence of The Spirit of Turtle and download many productions for free...

Luckily, a quick investigation and searching contact with the providers of the shops back-end, proved there was "only" a problem with an application update of the Digital Assets engine.

It somehow RE-E-mailed all orders from the past to our clients, which proved to be a lot after all;-) I was surprised...

So as you can imagine, it has been a bit of a chaos at the office this morning in stead of a peaceful mixing/editing session for the next production to appear.

So, FALSE ALARM and you can discard all these e-mails, or, if you lost some files, you can re-download them after all! Maybe the only good news in the midst of this mess.

I sincerely apologize for this horrible quirk, although there was nothing I could have done about it as it is a problem of some application under the hood of our Shopify host.

Enjoy the rest of your day and great music!

Warm regards,

Bert van der Wolf
Producer, Recording Engineer

The explanation of the host:


24-08-2022: Binaural Headphone releases


The High End Audio community, and more specifically the members in it who are mainly using headphones, have been asking for quite some time for a true High Res format for the Binaural experience of our Immersive Audio productions. The regular platforms all provide a Dolby Atmos permutation of compressed MP4 and this does not suffice for us for sharing our content.

That is why The Spirit of Turtle decided to produce binaural versions, exclusively for standard headphones, in decoded True HD 48kHz / 24 bit and 96kHz / 24 bit and offer those in FLAC format on the platform. These are directly derived from the 9.1 master files used for our AURO-3D and True HD Dolby Atmos releases.

This avoids the need of a decoder in either the player application and/or hardware processor and one can enjoy the Immersive presentation on any regular headphone. Of course these versions are not suitable for speaker playback!!!

From today on we will add more and more productions in this fabulous format, so more people can experience our 9.1 Immersive Audio productions, not only the once with an elaborate 10ch speaker set-up.


21-08-2022: New Variants for several productions

Over the years there have been different demands for digital formats and when The Spirit of Turtle platform was conceived, not all available productions were available in all permutations yet. We however keep steadily working on mastering those options and adding them to the catalogue. F.i. CC72302, Christoph Prégardien with Andreas Stair only appeared as SACD, so the DXD original recording and the DSD128/DSD256 versions derived from those were not prepared for release yet, but only the DSF files. Now we have added those and many will follow. It is a lot of work and digging in the archive though, but keep checking and/or asking us for them, so maybe your favourit production can be pulled forward.


20% Summer discount until August the 15th!!

Use discount code: SSD2220

First True HD Dolby Atmos titles soon available.

The past few months we have been participating with several producers in the High Resolution Audio community for the development of a downloadable format for "Dolby Atmos True HD". Until now this lossless format only appears on physical Blu-ray disc, but several customers have been asking for a file-format to be able to stream our music through their Atmos set-up in Immersive Dolby Atmos.

Normally only a compressed mp4 format is available through Apple Music and several other platforms.

The solution for now is packing the 48kHz/24 bit ADM into a 'MKV" video container and first testing has proven to be very successful. All the Dolby Atmos formats decode seamless, so also our 5.1+4 Immersive content. One can also enjoy the Binaural headphone version.

Over the coming period all our immersive titles will become available in this format, next to of course 9.1 AURO-3D.



All HQ|NORTHSTAR recordings featuring on the ACCENT (Note 1 Music, Germany) and the ETCETERA label will become available on The Spirit of Turtle platform in all high resolution formats, both stereo and Multi-Channel. Featuring La Petite Bande / Sigiswald Kuijken, Ars Antiqua Austria / Gunar Letzbor and The Amsterdam Combattimento Consort / Jan Willem de Vriend. This complements the catalogue of productions in the Web Store nicely for all the wonderful productions with these musicians we recorded. The coming months the titles will gradually be added.


Ars Antiqua Austria | Gunar Letzbor

This week 10, Stift Lambach Austria. Ars Antiqua Austria, Gunar Letzbor, Jan Krigovsky, Markus Miesenberger, Nina Pohn. Forgotten composer Ivanchiz, again Mozart quality…

NEW TSoT production, to be released coming July.

Maurice Ravel 

Lina Tur Bonet, Violin. (on gut strings)
Marco Testori, Cello.  (on gut strings)
Pierre Goy, historical piano and Luthéal

This week 9 recording works for violin, cello and piano by Maurice Ravel. The famous Tzigane and sonatas for Violin/piano and violin/Cello.

We are able to use original instruments from the museum MIM in Brussels.

Recordings with The Hague Residentie Orchestra /Jan Willem de Vriend

Schubert Symphony no. 6 ‘Die Kleine’ in the brand new Amare concert hall in The Hague.

"The Pope" of AURO-3D  visits The Spirit of Turtle

After many years of anticipation, finally, the godfather of AURO-3D, Wilfried van Baelen (Galaxy Studios, Belgium and CEO of the AURO group) visited the HQ|NORTHSTAR / TSoT studio to experience the recordings we produced in the (his) 9.1 format, on our terms and with our specialized monitoring of Merging Technologies NADAC+POWER+CLOCK, Spectral Audio Amps and Avalon Acoustic monitors. All in full immersive DXD of course. Wilfried was awe struck to tears about the results and what the system can deliver under these ideal circumstances. 

Wilfried said "Bert Van der Wolf exceeded my expectations which where already very high. He is an artist in getting the sound so pure and so natural for which he designed a special microphone setup (partially based on boundary mics) which allows a very high level of signal in each loudspeaker although that is not the way I experience it. At a certain moment, he put off the lights and it felt like the musicians were playing in front of myself sitting in the place where they recorded. Bert did countless productions in the Galaxy Studios Hall which I know very well. When he played them in his studio in that ultimate audio quality in AURO 9.1 it felt like I was in there in the same room as the musicians were playing. It is one of the most natural reproductions of sound I ever experienced"

His warmhearted approval on our take on AURO-3D makes us proud and confident to continue with this wonderful format.


Launch of AURO-3D Productions

The spirit of Turtle will release some 50 productions over the coming months that have been recorded in the 9.1 AURO-3D format. In close collaboration with the AURO team in Mol Belgium, all original 10ch DXD recordings will be encoded in the standard 96kHz/24bit FLAC for distribution. The format has the 4 height channels encoded in 5.1 files, which are backward compatible on all standard 5.1 Surround Sound systems, but with a dedicated AURO-3D encoder will deliver the genuine 9.1 result. For reference on the recording technique HQ|NORTHSTAR / TSoT is using find this article in our Blog posts & News section.


Nominated for an "Edison Klassiek"!
Song Cycles - Die schöne Müllerin / Schwanengesang / Winterreise
Congratulations to Christoph Prégardien, Andreas Staier and Michael Gees!


Vintage Challenge-Vanguard / HQ|NORTHSTAR productions are gradually added over time and for the first time available as high resolution digital download now!



The International Classical Music Awards (ICMA) nominees are publicly announced.
We are honored by the nomination of the late Bernard Haitink with Bruckner No.7


On location Recordings / 6-9 November 2021


Cappella Pratensis
Den Bosch Choir-books Volume 3


If it's Saturday, it must be Heusden!

The next episode in the great adventure with Cappella Pratensis, recording the Den Bosch Choir-books. What a joy to hear this magnificent vocal group filling the luscious acoustic of this great church in Heusden where the sun beams through with glorious rays of light. An inspiring environment to perform these renaissance gems.


On location Recordings / 2-5 November 2021

Stavanger Symphony Orchestra / Andris Poga / Baiba Skride
VASKS, PETERIS : Musica appassionata
PROKOFJEV, SERGEJ : Konsert for fiolin nr 1
TSJAJKOVSKIJ, PJOTR : Symfoni nr 6 "Pathétique


If it's Wednesday, it must be Stavanger!
Leading/producing recordings for NRK, the Norwegian TV/broadcasting corporation. Trying to deliver the best sound ever without being visible;-) Complex contraptions from the ceiling.

After 30 years waiting, finally Tchaikovskys Symfonie nr. 6, Pathétique, my all time favorite composition. A dream come true!
Thanks Stavanger Symfoniorkester




On location Recordings / 28-31 October 2021


Collegium Wartberg 430, Jan Krigovsky.

If it’s Friday it must be Bratislava!

New project for the Spirit. Contrabas Concerts by Johannes Matthias Sperger, famous contrabas player and composer(1750-1812).



    On location Recordings / October 7th 2021


La Sfera Armoniosa / Mike Fentross Concerti Grossi

Pieter Hellendaal, live concert.

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