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Restoring Catherine Christer Hennix’s recordings of Karlheinz Stockhausen’s Unbegrenzt

An email exchange with Robin Maconie

Originally published on April 02, 2021

Back in January, Robin Maconie, a composer, writer, and Stockhausen scholar from New Zealand, contacted me with technical questions concerning Catherine Christer Hennix’s 1974 recordings of Karlheinz Stockhausen’s Unbegrenzt, which I have restored and mastered for a vinyl and digital release on Blank Forms. Below are my email replies from January 29, and February 24, respectively.

January 29, 2021:

Hi Robin,

The original reels have been transferred at 96kHz through a Lavry Gold AD-122-96 converter. No noise reduction was used during the transfer.

The restoration was made with the Cedar Studio suite, some light noise shaping, and spectral retouching. The tape was in relatively good shape, with no baking necessary. The recording turned out to be in M/S like the remaining reels I've been working on for the other two editions on Blank Forms.

The M/S decoding was made with an analog matrix by Roger Schult, EQing in the digital domain with DMG Equilibrium, and an analog Fairman TMEQ for the finish. No dynamic processing was used, in general, Christer wished to stay as authentic as possible to what's on tape.

Please let me know if you have further questions,

February 24, 2021:

I spoke with Catherine Christer Hennix and also heard back from the transfer engineer in the meantime concerning the technical aspects of the recordings of Unbegrenzt, and I can give you more in-depth background info now. Let me address your questions one by one below.

Best regards, and thanks for your patience,

The piece was recorded in Mrs. Hennix’s rehearsal studio in Stockholm in 1974 on 1/4" tape by photographer Rita Knox, using a portable Nagra IV–S and a Schoeps M/S microphone kit, items on loan from the local broadcast station. There was no Dolby noise reduction involved since the Nagra didn't offer such a feature.

The setting comprised various speakers surrounding the players, some of them self-build. The instruments used for the performance were miked with –to quote Hennix– “toy-like“ Sony microphones fed into a battery-powered consumer grade 6-channel mixing board, a Sony MX-12, introduced by the company in 1973. This console only has unbalanced inputs and was known to be prone to noise, distortion, and catching interferences; the output was sent to the speaker array to be amplified at high levels. As you may know, Mrs. Hennix was impressed by bands she saw live in the States, i.e., the MC5, which performed their music at extraordinary, maxed-out levels.


If no noise reduction was used during the transfer, did you listen to the tape played back on an analog speaker system prior to remastering? Did you keep any notes? What state was the tape?

The transfers were made in 2018 at Calyx Mastering Berlin by Andreas Lubich, a seasoned mastering engineer, friend, and colleague with whom I have collaborated for 27 years. The reels were in good condition, and no baking was required. The transfers of roughly 13 hours of material in total were made during a series of sessions with Hennix in attendance.

The full-resolution files I have received are of the highest integrity and allow me to hear an exact copy of the reel's content in my room. My studio‘s acoustics are optimized for mastering, and I didn’t compromise regarding the accuracy and transparency of my monitoring and processing chain. I aim to hear precisely what the source offers and then take it from there. I'm working on a wide range of material, some brilliantly produced, others less so. To me, this makes no difference. I'm trying to get the best possible results from the material I receive, but I do not twist audio to make it fit within certain standards or meet specific expectations except to create a correct-sounding master. I cherish authenticity, and I'm certainly not afraid of noise. Working with historic reels, instead of working from a digital production, involves a particular layer. To me, the tape, 78 disc, wax cylinder, or acetate becomes part of the performance, and I want to present it in the best possible light, ideally by applying only as few adjustments as necessary to make it enjoyable. My goal is to create an optimized copy of the medium that represents a recording as the artifact it is.

I was surprised to hear an almost continuous hiss throughout. The most obvious explanation would be that Dolby expansion was used in the original tape, which was not de-Dolbyed in the remastering.

Dolby would have been used during the transfer if it had been applied during recording. Since the noise level in the flat transfer of the reels is far from identical in the mono and difference channel, it is safe to say that it is part of the performance, the band's unique sound. Broadband noise contains much of the spatial information. Pull it down, and the stereo image may become dull. The tape hiss present was average, the vast amount of noise was introduced by the gear and the high level of amplification of the instruments. This is what I hear from the flat transfers of the tapes, and it was crucial to me to preserve the sonic signature with integrity in the reproduction masters.

The audio panorama was also strange and appeared skewed to the listener's right when played back on speakers, though for some reason the effect on headphones was less prominent.

The decoding of the M/S signal was made with great care. What you hear in the masters is the point where the decoding to stereo sounded best to me and revealed the most details. As you can tell, the noise level is pretty much stereo now because I used it as a reference during the decoding.

If indeed the original tape was recorded with a coincident pair, the stereo imaging should be adequate, providing the players were correctly positioned originally.

M/S is a fact. The flat transfers have one channel with the mono signal, while the second channel mainly contains room information. From the decoded stereo, you can tell that the instruments were not distributed evenly across the stage. The multi-speaker setup added another level of phase mix-ups that had to be addressed during mastering.

However, that still does not account for the inserted tape segments featuring Japanese drumming which recur from time to time. These prerecorded elements would have to be reproduced from equipment of some sort, and balanced with the live players. It is unclear to the listener where the prerecorded elements are located in the stereo panorama.

There are no pre-recorded or sampled percussion instruments present in the recordings. What you hear is a set of temple blocks and a tabla played by Hennix, along with various playing techniques used on the tam-tam by Hans Isgren. Those instruments can be heard either dry or processed through a tape delay or ring modulator. Pre-recorded audio used during this performance contains experiments with speech synthesis conducted with a mainframe computer system created by Hennix at the Royal Institute of Technology in Stockholm. The choice of the tam-tam, temple blocks, tabla, and ring modulation for this performance was made in reminiscence of Stockhausen’s work.

Since no technical notes relating to the original recording are included in the sleeve notes, did any original notes survive along with the tape?

The tapes came without specific notes apart from title, date, and tape speed, please see below.

Are you perhaps familiar with the Stockhausen recording on DG and the Shandar recording of the same piece? Whatever one might think of the sounds made, the quality of recording is amazingly clean and sharp, and essential technical information is provided.

I know the DG 7LP set well. You are comparing the high Westdeutscher Rundfunk standard available to Stockhausen to a room recording made with modest equipment in a rehearsal studio. Unbegrenzt is a private recording of an ensemble that Hennix herself has described as “the most rejected band ever formed in Sweden”, a band that looked to perform live for an audience, the context in which Hennix wants her music to be experienced. The recordings were made so the group could listen back to them to see how they sound from an audience's perspective. Back then, there was no intention to have those recordings released by a label, let alone by Deutsche Grammophon. Today, many people feel blessed that the archival recordings are available in editions made with great enthusiasm and a significant level of care. The music became a holy grail for people like me, and Unbegrenzt has its unique place among the pieces recorded by Hennix and her The Deontic Miracle group in Stockholm between 1974 and 76.

Ms Hennix may have asked for the recording to stay true to the tape, but that could be because she has forgotten or is uninterested in such matters.

The masters were prepared in close coordination with two of Hennix's collaborators, Marcus Pal and Hilary Jeffery, partly because, at that time, she didn't have a reliable system available to monitor the process properly herself. Everybody involved in the process was familiar with the quality of the flat transfers of the tapes. Five people approved the results in addition to the transfer engineer and myself. What you hear on the LP, or from the lossless digital formats, represents what is on tape, decoded to stereo, cleaned from excessive tape hiss and gently re-EQ'ed. No dynamic processing is involved in any of the masters apart from manual de-essing to get hold of some moments of clanking bursts.

Or because any technical record has been lost, in which case care would be needed to interpret the original intention.

The tapes are no Abbey Road, Columbia, or WDR recordings where you would see notes concerning test tones for calibration, EQ settings, even info on the specific EQ models used, noise reduction, etc. The notes on the slipcases don’t go beyond the recording date, title, and tape speed. That's all it takes for them to be played back correctly from a well-serviced 1/4“ machine.

This is a nontrivial matter because Stockhausen's text pieces are intended, above all to convey the reality of a musical event taking place spontaneously in the moment, which is a musical phenomenon at the opposite extreme from the theory and practice of digital music in 1968 - and even in 1974, as represented by Max Mathews's music composing package (which eventually became MaxMSP).

If you ask me, it doesn't come closer than what we have on tape here. The intention is perfectly realized. From a purely technical aspect, Stockhausen and Hennix in the mid-1970s could not be further apart. To stay only with the DGG version of Aus den sieben Tagen, the 1969 recordings were made at Georg-Moller-Haus in Darmstadt (the location used for the Musik für ein Haus event one year earlier), a specifically selected space where a team of white coat engineers would set up the finest recording gear available, including selected microphones for each of the instruments. Stockhausen’s console, credited as Filters and Potentiometers, was, of course, custom-built for him, and if you’re familiar with the level of standards, norms, and skills at work in German broadcast stations, this console had to be state of the art.

In other words, a text piece asks the general question, “How do you capture an impression of organic reality through a medium that reduces reality to a string of numbers?”

I'm unsure whether you are questioning the truthfulness of analog tape transferred to digital (a string of numbers). A well-made transfer will represent the content of a tape 1:1. The string of numbers analogy may be accurate for early digital audio. If you transfer an analog medium to digital today through carefully chosen converters, say at 96kHz/32 float, you will get an exact copy of:

A/ the sound captured on the tape itself

B/ the sound and character of the analog playback device, a Studer A812 in this case, which is optimized so it won’t add a sonic footprint at all but rather reproduce the source as faithfully as possible by analog means.

If you capture from a tube-based reel-to-reel machine, say an early generation Telefunken M5, the machine will come with a good portion of its own vibe, which will also be captured digitally. The transfer will sound like the tape played back from the valve unit.

If the content of the reel sounds pristine, the digital file will deliver exactly this. The string of numbers is so vast and quick it will recreate analog sound without adding or subtracting in all its analog smoothness, detail, and character. Digital audio can be outstanding today as long as it’s done right. It offers much more precision than analog ever had and leaves nothing to be desired, even by die-hard analog folks like myself or my teachers. All preconceptions from the '80s to the late '00s are gone.

You may think such a view as old-fashioned, but Unbegrenzt is a pointed philosophical statement by the composer at a critical point in his life, a kind of Hamlet moment where the composer asks: "To be, or not to be?"

While listening to the DGG 1969 recordings now, I can’t help but think that various of the players involved were not entirely ready for the Intuitive Musik. I admire Stockhausen’s work and his classic ensemble players in general. Hymnen is among the best tape music I know, and I have performed Spiral several times solo and Kurzwellen as part of an ensemble. However, much of his recordings of Intuitive Musik pieces sound weak and undecided to me, and I can’t help but wonder how they would have sounded if Stockhausen had worked with more avid ‚free’ improvisers instead, people from the British (AAM, SME), German (FMP) or Dutch (ICP) scenes, for instance. The Scratch Orchestra? I don’t intend to disrespect the players; I only question if all of them were the right choice for this specific pieces. I hear well-made recordings of sometimes rather unsatisfying performances, with many cliches in play that can make spontaneous music so uninteresting. This certainly does not affect all the pieces, but Unbegrenzt, in my opinion, is clearly among them.

The 1974 recordings of Unbegrenzt by Catherine Christer Hennix and Hans Isgren are different in many ways. I imagine the band would not have turned down the opportunity to record their material at a radio station or in a dedicated electronic music studio. What we had available today would sound different, a period high-end capture probably. I first heard material from Hennix’s private archives from the mid-70s in 2005, a 96kbps online stream by Dutch VPRO radio. Back then, I could only hope that the material would be released at some point. In fact, I thought the recordings were made at EMS and was surprised when I finally received the transfers since they sounded so rough and edgy, not like an electronic music studio production at all. Next, I fell in love with their unique sound. The recordings are outstanding documents to me.

During our conversation about recording, interpretation, and capturing a performance for later playback, Catherine Christer Hennix pointed me to the following paragraphs from Wittgenstein’s Tractatus:

The gramophone record, the musical thought, the score, the waves of sound, all stand to one another in that pictorial internal relation, which holds between language and the world. To all of them the logical structure is common. (Like the two youths, their horses and lilies are in the story. They are all in a certain sense one.)

In the fact that there is a general rule by which the musician is able to read the symphony out of the score, and that there is a rule by which one could reconstruct the symphony from the line on a gramophone record and from this again —by means of the first rule— construct the score, herein lies the internal similarity between these things which at first sight seem to be entirely different. And the rule is the law of projection which projects the symphony into the language of the musical score. It is the rule of translation of this language into the language of the gramophone record.


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