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KiA few quick questions to:
Todor Dimitrov
Master Tape Sound Lab

Todor Dimitrov
tel.: +302 3920 24373



Country of Origin: Greece

Wojciech Pacuła ǀ Todor Dimitrov

Master Tape Sound Lab ǀ Wojciech Pacuła (nr. 13-16)

Published: 1. August 2012, No. 99

„MTSL offers high quality 1 generation master tape dubs. Currently our catalogue contains 55 titles of diverse music, from jazz to classic and other genres, all of which were recorded onto/from 1st generation master tape with strictest quality standards. The MTSL master tape dubs are recorded directly from the original master tapes, as MTSL owns those originals, and have a license to release them in limited numbers (100 per title).”

Such advert would be perfectly normal in “Hi-Fi News” magazine from 1960s or 70s. It would probably appeal to music lovers with its purist approach and its guarantee that the copies had been made directly from the master tape, but otherwise it said something that would have been known and understood. For it would be using terminology related to reel tapes, and so to reel to reel tape recorders.

'Tape recorder' is defined by the Encyclopedia of Gazeta Wyborcza as “a device for recording (registration) of audio signal (sound processed into an electrical signal) on magnetic tape and for its playback.” The definition further mentions that there are analog and digital tape recorders, and the former are divided into reel to reel and cassette. Interestingly, the Dictionary of foreign words published by Wydawnictwo Naukowe PWN in 2007 (ed. Lydia Wiśniakowska, Warsaw 2007), does not contain the word, however, it lists the word ‘VCR player’. Either the word ‘tape recorder’ became so widely accepted and used that it was not considered a foreign word any longer, or it simply disappeared. And yet, until the end of 1990s magnetic tape was the primary means of sound reproduction and RECORDING in almost all audio systems, or simply at home. It largely concerns a cassette player. When it comes to reel to reel, every recording studio, every theater or a local culture club had at least a few of them, and they ruled all over. Today is completely different.

Until recently, film directors wanting to emphasize some eccentricity, oddity or just difference of a movie character would equip him or her with an extensive audio system, with turntable taking the central place. The movie that gave impetus to this was of course A Clockwork Orange by Stanley Kubrick (1971), with the Transcriptor Hydraulic Reference turntable. But if we recall such diverse movies as What Women Want by Nancy Meyers (2000) with a Rega turntable, the Clearaudio Reference featured in Tomb Raider (dir. Simon West, 2001 ), or – among the latest – an unidentified turntable from The Untouchables by Nakache Olivier and Eric Toledano (2011; there are still debates on French web forums what it was – the whole system came from French company Advance Acoustic, but the turntable could not be seen clearly enough), we can see what’s going on. And the list could be much longer, because we cannot overlook House, M.D. TV series (dir. various, 2004-2012), with the SOTA turntable, or actually two – one in the hospital and one at home.
All these movies, apart from obvious differences, however, have one thing in common – the turntable. Moreover, it is almost always classical music, jazz or blues, and people who listen to it are old, sick, emotionally unstable, socially awkward or possibly snobs.
It’s been quite some time though I have not seen a reel to reel player in a movie. That’s until I saw The Girl with the Dragon Tattoo (dir. David Fincher, 2011), a remake of the Swedish original. And who has the reel to reel (probably a Tascam)? Martin Vanger, a pervert, murderer, deviant played by Stellan Skarsgård. What is he listening to? To Enya, on the C22 preamp and the Mc275power amp from McIntosh (tube amplifiers are another proof of perversion; House had a QUAD system at the home – the QUAD-II preamp and monoblocks…). In his “normal” life Vanger has a system from Bang&Olufsen, with the brilliant BeoLab 5 loudspeakers. As you can see, nothing’s changed – whether it’s a turntable or tape recorder, the message is clear: people who use them are serious loonies. And / or unhappy.
Still, we need to fight stereotypes, though it’s extremely difficult. How to explain that all those characters in all the movies I mentioned are perfectionists, obsessive compulsive people, and what the movie’s art director takes for an attribute of mental disorder is actually one manifestation of the pursuit of perfection. Often degenerate but just as often completely understandable. And over the last 70 years the turntable has been a perfect sound source for most music lovers / audiophiles. The number one source on an absolute scale remains tape recorder.

If, however, thanks to the former analog still holds its own, reel to reel recorders disappeared from home audio systems almost entirely, remaining only in recording studios. They were extremely difficult to use, the tapes were very expensive and, besides, most companies did not want to let go of priceless mother tapes, or even their first or second generation copies. The final blow came with digital revolution bringing almost free copies on CD-Rs. And with that fell the concept of music playback from true reference source, since vinyl is just a reflection of what’s on the original tape.
Until recently, that is, when once again we can see companies offering open reel tape copies of mother tapes, reel to reel tape playback equipment, etc. That was quite visible during High End 2012 in Munich (see HERE), where some exhibitors decided to play music back from that type of source.
One of the more interesting presentations was that by Master Tape Sound Lab, represented by Mr. Todor Dimitrov. It was interesting, because not only was music played back from the large Studer A80 tape recorder, but the company also offers modifications of Studer recorders and – above all – pre-recorded reel tapes. What is this company, what does it do, what is its philosophy of sound? That’s what I asked Mr. Dimitrov.
Before we moved on to my questions, he hinted that he’d read with interest my bio in “” (see HERE) and that, just as in my case, his first good turntable was a Unitra with MM cartridge, and his first own built component was a phono stage. So it is all intertwined and connected.
And one more thing – I just received first tapes for auditions and will make it the subject of next Krakow Sonic Society meeting. If everything works out – as I hope – you will soon read my report.

Wojciech Pacuła: Tell us something about your company.
Todor Dimitrov: Master Tape Sound Lab is a diverse group of associates, including “old school” recording engineers, audiophiles, tape techs and musicians, devoted to the goal of live-like music recording/reproduction. Our group is very international, integrating an R&D lab in Denmark, an analog studio in Greece, as well as an analog recording legend – Kostas Metaxas, based in Australia. [Ed. note: his company, Kostas Metaxas, manufactures high quality amplifiers; see HERE.]
While we appreciate any spectrum of well recorded good music, regardless of technical means and format, our focus is on enhancing the unique advantages of analog master tape recording and reproduction, using proprietary upgrades, combining the simplicity of pure analog recording with the latest developments in electronics.
We work on the advancement in 2 main areas: (i) a 60+ title catalogue of outstanding musicians, recorded and released exclusively on top quality master tape dubs – 2 track, 15 ips; and (ii) top-quality research and upgrades of Studer tape machines, integrating top-quality components, unavailable at the time of original design. Our audio philosophy is simple: pure music recording and reproduction, with dedicated gear that has no sound of its own – just transparent.

WP: How did it all began?
TD: The master tape endeavor started 2 years ago, when I became a friend with Kostas Metaxas and auditioned several of the original master tapes he recorded directly onto 2 track analog tape, using his own modified Stellavox SM8 machine. The quality was simply breath taking: lively natural sound, multidimensional stage, huge dynamic range – just vivid and real. Even when we compared Kostas’ tapes with other original production master tapes of acknowledged reference recordings, the results were exceptional. This is due to Kostas’ quest for the most natural recording method, using simplistic microphone set ups, dedicated gear and no processing at all – yes, no limiters, compressors, equalizers and alike, even no outtakes.
The listening sessions resulted in a release agreement and a long term partnership, giving more analog life to the long list of masterpieces. Offering about 60 unreleased titles on top quality tape source was complemented by a respective tape gear upgrades. Our choice was to use and upgrade various Studer master tape recorders, after conducting an in-depth research on available options, parts and seasoned expertise.

WP: What kind of equipment do you use?
TD: Most of the titles we offer are sourced from the original master tapes, recorded by Kostas on his modified Stellavox machines: Stellamaster SM8, Stellavox SU8, Stellavox TD9 (1/4" & 1/2" tape). Our re-recording gear consists of MTSL-modified 2 track Studer machines (A80RC and A820 with 1, ½ and ¼ inch tape). Each master tape dub release is recorded in real time, either directly from the original master or from a half inch 2-track safety master, at 15 ips, using the IEC tape equalization standard. The source masters are mostly high output BASF SM 468, and the master dubs are RMG SM 911 and SM900. The combination of top-notch studio mastering machines, expertise and tapes gives a transparent, uncolored performance – a must hear experience. Our tape machines are equipped with high performance extended response custom record and playback butterfly heads, and in-depth modifications of all audio stages.

When recording music at our studio and on location, we follow a similar approach to the one successfully used by Kostas: few customized microphones (e.g. pair of B&K4135 or a pair of Neumann TLM 50s) with a simple stereo set-up, direct recording on high output tape, no compression, limiting or equalization – pure analog recording.
Other gear include:

  • Cables – MTSL-Hybrid, Van Den Hul MIC Hybrid, Mogami 2534 Neglex;
  • Monitors: MTSL active, with Scanspeak drivers;
  • Amplifiers: MTSL Triamp
  • Power: MTSL Balanced Power

The tape machines modifications we make/offer include a completely novel own design of super-regulated high current power supplies for the audio section. The entire signal path is modified by enhanced audio cards (repro, line, record, preamp, etc.) on the basis of top-quality components/upgrades that Studer would have used if they had to do the machines today. This involves precision film capacitors (replacing all electrolytic, tantalum and solid aluminum caps on the signal path with mostly polypropylene film caps), discrete/hybrid low noise op-amps and other superior active devises. Furthermore, we use much shorter signal path by removing unnecessary options such as muting switches, un-buffered VU meter bridges, mono-stereo switch cards, record head reproduction (sync) for overdubbing, etc. All the upgrades and modifications are implemented on the basis of the following criteria:

  • Respecting the performance and merits of the original Studer designs, considering what the Studer designers would have done with today’s better quality active and passive components;
  • Rigorous R&D and measurement tests, ensuring that original specs are substantially surpassed, e.g. increasing the effective dynamic range to 90 dB, almost halving THD, as well as extending the frequency response to 8 Hz – 33 kHz (+-1 dB);
  • The ultimate criterion is critical listening, to ensure transparent, uncolored realistic sound, where one listens to the music alone, not to any particular component. These tests guide us what to look for in measuring performance as distortion and other factors per se are not sufficiently reliable determination of audio quality.

WP: How did you convince Mr. Metaxas to give you master tapes? I know it is really hard…
TD: After testing Kostas’ tapes we developed a friendship and partnership based on common values and appreciation of natural reproduction through direct tape recordings. Initially I acquired a few of his original masters to use them as reference. Soon after I realized their exceptional sonic quality and the purist recording concept, we agreed to give those works further life within the same tape format. Kostas is a key partner and asset at MTSL, backing our venture with his vast experience as a proven seasoned analog recording engineer and audio designer. His first ever recording made on a Stellavox tape machine was compared to the legendary Bob Fine work for Mercury Records in the 50's and 60's (Ken Kessler, “Hi-Fi News&Record Review”, March 2004, see HERE). This inspired him to invent various modifications and record concerts with the same purist 2 microphone approach of the 50's and 60's.
Kostas has been recording concerts since 1986 including legendary performers such as Charles Dutoit, Jean Yves Thibaudet, Konstantin Lifschitz, Chick Corea, Gary Burton, Takacs, Il Giardino Armonico, James Morrison, Mike Nock, ACO, ASQ, Jerusalem Trio, Yvonne Kenny and Fritz Hauser and more recently, UK’s Sir Neville Marriner. Many of these great musicians are on our tape catalogue. Kostas recorded over 300 classical & Jazz acoustic concerts using his modified Stellavox SM8 & TD9 analogue tape recorders, the basis for his ongoing research to make incremental adjustments to his equipment. Currently MTSL releases under license about 60 of his best recordings on 1 generation 2 track master tape dubs, directly from the original masters, representing a rich spectrum of musicians and genres. For further details on Kostas and his recoding technique, please visit: LINK

WP: How is tape sound different from LP and hi-res digital audio?
TD: Sonically, the first to third generation 2 track dub from a well recorded master tape, is simply unsurpassed by any of the available formats today, with due respect for the advantages high resolution offers. The difference in sound quality is dramatic, as confirmed by various critical listeners. The tape source presents a more dimensional, deeper and far more realistic sound stage, with unmatched airy ambience and detail, even when compared to the best LPs or SACD/DVD-A, etc. So far, a well modified and calibrated tape machine is the only gear where you can hear the “line out” as the exact match of the microphone-fed “line in”. Straight and simple. Not available on digital or LP.

In terms of storage and durability, the modern tapes outperform LPs and CDs in many ways, contrary to many myths. While the original CD promise was “perfect sound forever”, we soon learned that both parts of the statement did not live to expectations – the digital recordings sound less alive and often last just a decade, due to ageing and wear. In contrast, LPs and tape in particular, degrade very smoothly over time, remaining fresh and playable even after very long periods. I have some tapes recorded in the 50-60ies and they sound fantastic.

The reasons why tape sounds substantially more natural and alive, relative to Lp and high resolution digital, are complex and many. Let’s touch upon a few:

  • Unlike digital audio systems, analog tape does not require band limiting filters, used to prevent aliasing distortions. Furthermore, while measured digital noise seems lower than analog tape hiss, tapes lack strange unnatural factors such as jitter - the effect caused by the variations in spacing of the discrete samples in time within the stream that make up a digital signal. Such variations typically associate with timing inaccuracies of the digital clock. Other sources of jitter are data-induced, where one part of the digital stream affects a subsequent part as it flows through the system. There is also power supply induced jitter, where DC ripple on the power supply output rails causes irregularities in the timing of signals in circuits powered from those rails. The dependency on accuracy of multiple discrete digital values on the clocks is inherent to digital recording and playback and has no analog equivalent, though analog systems have their own temporal distortion effects (pitch error and wow-and-flutter, which are unnoticeable if kept within limits). Periodic jitter produces modulation noise and is often compared to analog flutter. There is also random jitter – even at a level of 10 ns it would cause unnatural sound artifacts. Unlike wow and flutter, jitter variations have a far higher frequency and for this reasons are less easy to perceive but are actually more annoying. As a result the rhythmic message, the pace of the most complicated musical plots is partially or completely lost, music appears dull, scarcely involving and apparently soul-less. While jitter appears undetected as such, it still causes reduction of the soundstage width and/or depth, lack of focus, and often puts a veil on the music.

  • Analog tape systems do not use discrete digital levels in which the signal is encoded. Thus, the original signal can be preserved within the dynamic range of the system. In contrast, digital systems have different type of noise, added due to quantization into discrete levels. This is much more disturbing than the noise-floor in analog systems. The digital-inherent distortion, often called granular or quantization distortion, has been pointed as a key explanation on the format differences. The quantization noise level depends on the number of bits of quantization resolution, decreasing exponentially with it. Therefore, with higher number of true bits of quantization, random noise from other sources (often added on purpose) tends to dominate or completely mask (but not remove) the quantization noise.

  • The professional tape recorder has a bias frequency of over 150 kHz. This relates to a 4-time higher sampling than a CD and is close to the highest digital resolutions used today. However, digital recordings, even at high-resolution, are still based on a flawed over-simplistic model of our hearing abilities. This is why the brain recognizes the digital granularity of the sound. If you compare high resolution PCM (192/24) and even SACD with tape, the difference in dynamics, both micro and macro is orders of magnitude better on tape. Tape gives incredibly better dynamics for its theoretically lower (but practically higher) dynamic range. The actual/perceived dynamic range and transient speeds of a tape machine are well beyond what the measurements would imply, with digital, it is the opposite.

  • While LPs and especially CDs have tighter limitations on their frequency response, a professional tape machine can be upgraded to 5 Hz – 50 kHz and this matters as such end frequencies are important for music perception, even when they are not registered by the human ear. For example, when a large truck on the street passes by we feel the vibes, although they are in the 3-8 Hz range.

  • Analog tape is the only recording medium that does not necessarily require limiters and compressors of the program as it has a very natural/musical frequency dependent dynamic compression ability itself. Even when the program peaks go into tape saturating levels, this is achieved smoothly and with naturally sounding distortion (on modern tape in particular). In contrast, an LP or CD require strict limiting and pre-compression as even a minor overload/clipping would damage the recording, hence the need to compress the dynamics well below the “red” zone. This is actually why AAD CDs sound better, contrary to the initial expectation that DDD should be superior – because the mastering on analog tape acts as a natural compressing agent, ceteris paribus, in this complex process.

  • While analog tape has some inherent noise (tape hiss, in our machines – well under the microphone hiss levels), it appears as a very low level signal in parallel with the music, just as the inevitable ambiance hall noises at a concert. In contrast, the digital noise (jitter, high frequency, etc.), while not separately noticeable, is actually integrated into the music, not appearing as a parallel ambience sound. As to LPs, they are closer to a tape in that respect, but a long process away from the original tape master, adding mechanically-induced interferences, both during the cutting and reproduction stages.

  • A tape captures transients and resolution extremely well, with LPs being inferior (mechanics inertia and alike). As to high resolution digital - it has some “sharp edge” - too-sudden artificial transitions/jumps, associated with the binary “bits” and the sampling-oversampling process, which sounds fast, but unnatural, hence often fatiguing, to the brain. Just like in the sea-sickness process, where what the brain gets from different receptors is contradicting, leading to undesired experiences.

  • Last but not least, let’s mention the multiplication effects. As a source, tape is most upstream, so if you make a closer generation dub, you will reproduce what is on the master. In contrast, with LP and digital, the signal goes via lots of gear and processing, each adding the otherwise minor deviations (e.g. distortion, response non-linearity, etc.), resulting in a combined effect of degradation. Of course, the same applies when analog tape is used for endless multi-track overdubbing, the fashion of the late 70-es and the 80-es – something we avoid in our work. As to digital – it also suffers from multi-track overdubbing. Not for the tape-related reasons (error accumulations with re-recording), but as a result of the mechanical “matching” of instruments/tracks. It just does not sound live/natural, but is widely used under the illusion that digital edits can offset the lack of talent - on both sides of the control room window.

WP: How do you generally feel about hi-res - is it the future of audio?
TD: High resolution digital has the potential to deliver quality, if implemented correctly. So far, it is making modest steps, with mixed results, not always delivering more than low resolution digital.
After DVD-Audio was abandoned, SACD followed. Nevertheless, the DSD can resurge, like LPs and even tape, particularly benefiting from improved AD-DA components and internet downloads. However, the road will be bumpy and slow. As one friend recently put it “I will not invest in virtual non-material carriers, whatever the promise is”. In other words, while CDs seemed to be phasing out, they will not be easily taken over by downloads, for various reasons.

While it is clear that DSD and SACD offer audible benefits for some kinds of material and recording techniques, the format was not adequately/widely used. Hence it faced premature abandonment. In 95% of the cases of DSD recordings, studios converted DSD into PCM to do the digital editing, thus lowering the quality to red-book CD level, effectively using DSD as a misleading marketing tool. The primary application for "pure" DSD was for some live recordings, edited without the use of digital signal processing. This was used to some extent in the classical field, but the majority of SACDs originate from studio multi-tracks, with a great deal of mixing, processing and other digital operations – where PCM was actually more appropriate.

The history of audio and video format wars only proves that quality was never a real priority – it was sacrificed for mass and convenience (e.g. Betamax vs. VHS; CD vs. SACD). I am skeptical if the industry will go out of this loop – and here I mean all industries, not just audio. Perhaps only a few crazy small companies like us will continue the quest for quality, advancing peculiar or obsolete formats, abandoned by the mainstream. Like the entire music production today, the high-end audio is in deep crisis, looking at yet another format - not to deliver better quality, but to make you re-purchase your collection yet once again, re-re-re-mastered, re-re-re-issued.

WP: What type of loss is to be expected between master tape and first generation copy?
TD: To understand correctly those losses, we have to clarify the term “master tape” as it is widely used but often misunderstood. Typically, the “original” master tape is a mix-down tape, that may already include several re-recordings, particularly if a multi-track overdubbing was involved. Some of the great sounding albums, e.g. Fletwood Mac’s Rumors, were actually sourced from second generation safety masters, as the originals were lost/damaged. The single of Phil Collins's In the Air was recorded on an 8-track, copied to 16-track for more overdubs, mixed to ¼” and dubbed to another ¼” tape to add more snare drum, which was then mastered to ¼” from which the lacquer and loop bins were made. That's 5 generations of tape, all without noise reduction – still a reference record for many.
In our case, the original masters are actually 2 track direct-on-tape session masters, so they are already at the ultimate upstream relative to the typical mix-down masters, used for LP/CD cutting. For that reason, even a 3rd generation transfer from our originals will have less deviations from the actual performance, compared to a first generation transfer from a typical production master used by a record label.
Technically speaking, each generation of a tape dub adds about 3 dB tape hiss. This is negligible in our case as both the source and the destination tapes are high output, recorded on top-notch gear with about 90 dB dynamic range. In practical terms, our master dubs do not have a noticeable sound difference, they sound virtually like the session tape. At the High-End Munich 2012 show we had a listening session of first generation dubs and the recording engineer, Kostas Metaxas personally confirmed that the sound was identical to the actual concerts he recorded. I can’t think of a better test.


  • 3 Songs after William Butler Yeats (2011) by Andrew Howes; see HERE
  • Ananke in La Mama Theatre recorded by Kostas Metaxas on “YouTube”, see HERE
  • Free WAV music sampler compilation to download from Metaxas website HERE