High Com

The High Com (also as HIGH COM, both written with a thin space[nb 1]) noise reduction system was developed by Telefunken, Germany, in the 1970s as a high quality high compression analogue compander for audio recordings.

High Com
Compander variants
Nametelcom c4High ComHigh-Com IIHigh-Com IIIHigh Com FM
Medium magnetic tapemagnetic tapemagnetic tape,
vinyl disc[nb 2]		magnetic tapeFM radio broadcasting
Target market professionalconsumerconsumer, semi-professionalsemi-professionalconsumer
Development start 1971/19721974197819781979
Introduction 1975/197619781979never(1981–1984)
Compander type linear fixed four-band[1] (crossover: 215 Hz, 1.45 kHz, 4.8 kHz)[2][3]broadband with pre-/deemphasis[1] from 1.2 kHz to 8.6 kHz[2]fixed two-band (crossover: ? with pre-/deemphasisfixed three-band (crossover: ?, ?)broadband with pre-/deemphasis
Compression 1.5:1:1.5[1]2:1:2[1]2:1:22:1:2?
Noise reduction 25–30 dB(A)[1][4][5]15–20 dB(A)[6][7]20–25 dB(A)[4]??
Calibration / ident tone alternating 550/650 Hz, −0.13 dB[nb 3]originally 440 Hz, later 400 Hz, 0 dB, 200 nWb/m[8]400 Hz, 0 dB, 200 nWb/m[4]N/AN/A
Tape leader 38 cm/s: red-white-black-white,[9][nb 4] 19 cm/s: blue-white-black-white[nb 4]??N/AN/A

The idea of a compander for consumer devices was based on studies of a fixed two-band compander by Jürgen Wermuth of AEG-Telefunken ELA, Wolfenbüttel, developer of the Telefunken telcom c4 four-band audio compander for professional use.[3] In April 1974, the resulting "RUSW-200" prototype first led to the development of a sliding two-band compander by Ernst F. Schröder of Telefunken Grundlagenlaboratorium, Hannover since July 1974.

However, the finally released High Com system, which was marketed by Telefunken since 1978, worked as a broadband 2:1:2 compander, achieving almost 15 dB of noise reduction for low[7] and up to 20 dB RMS A-weighted for higher frequencies,[6][7] while avoiding most of the acoustic problems observed with other high compression broadband companders such as EMT/NoiseBX, Burwen or dbx.[6][10][11][nb 5]

In order to facilitate cost-effective mass-production in consumer devices such as cassette decks, the compander system was integrated into an analogue IC, TFK U401B[6][10][12][nb 6] / U401BG[6][nb 6] / U401BR,[7][6][13][14][nb 6] developed by Dietrich Höppner and Kurt Hintzmann of AEG-Telefunken Halbleiterwerk, Heilbronn.[6][15]

With minimal changes in the external circuitry the IC could also be used to emulate a mostly Dolby B-compatible compander as in the DNR (Dynamic Noise Reduction) system[7] for backward compatibility. Consequently, second-generation tape decks with High Com incorporated a DNR expander as well, whereas in some late-generation Telefunken, ASC and Universum tape decks this even worked during recording, but was left undocumented for legal reasons.

High-Com II and III

Nakamichi, one of the more than 25 licensees of the High Com system,[6] supported the development of a noise reduction system that could exceed the capabilities of the then-prevalent Dolby B-type system. However, it became apparent that a single-band compander without sliding-band technology, which was protected by Dolby patents, suffered too many audible artifacts. So, High Com was further developed into the two-band High Com II and three-band High Com III[nb 1] 2:1:2 systems by Werner Scholz and Ernst F. Schröder of Telefunken assisted by Harron K. Appleman of Nakamichi in 1978/1979.[6][16][11] The two-band variant was eventually released exclusively as Nakamichi High-Com II Noise Reduction System later in 1979,[4][11][6][17][18][19][nb 7][nb 8] increasing the amount of noise reduction on analogue recordings and transmissions by as much as 25 dB A-weighted.[4]

High-Com II for vinyl

While originally designed for tape recordings, Nakamichi demonstrated the usage of High Com II on vinyl records as well in 1979.[11][nb 2][nb 1]

In 1982, the same AEG-Telefunken team, who designed the High Com noise reduction system,[6] also developed the IC U2141B for the CBS Laboratories CX noise reduction system for vinyl records,[6] a system also incorporated into FMX, a noise reduction system for FM broadcasting developed by CBS.

High Com FM

Similar to the earlier Dolby FM[20] system in the US, a High Com FM system was evaluated in Germany between July 1979 and December 1981 by IRT.[6] It was also considered to be adopted for AM broadcasting.[21] Based on the High Com broadband compander, the system was field-trialed in public FM broadcasting between 1981 and 1984. However, despite the improvements it was eventually not introduced commercially because of the listening artifacts it created for receivers without expander.[22][6][21][23][24][25][26][27][28][29][30][31][32]

Impact

Besides Telefunken's own CN 750 High Com compander box, other companies also offered external High Com compander boxes such as the Aiwa HR-7 and HR-50, the Rotel RN-500 and RN-1000,[33][nb 9][nb 10] or the Diemme Sonic-distributed Aster Dawn SC 505[34][35][36][37][nb 11] and the Starsonic DL 506, as distributed by D.A.A.F.[38][39][40][nb 11] A low-cost implementation of the Telefunken High Com system as external compander box became available as Hobby-Com,[10][41] developed by Telefunken product development[6] and Thomsen-Elektronik[10] for WDR, distributed by vgs,[10] and promoted for do-it-yourself assembly in the popular TV series Hobbythek format by Jean Pütz on 7 February 1980.[10][6] In 1981 and 1982, do-it-yourself High Com kits were introduced from elektor (elektor compander/Hi-Fi-Kompander)[5][42][43][44][45][46] and G.B.C. Amtron (micro line High-Com System UK 512 (W)).[47][48][49] The only compander available for High-Com II was Nakamichi's High-Com II[nb 1] unit.

More than one million High Com systems were sold between 1978 and 1982.[13][50] While implemented in dozens of European and Japanese consumer device models and acoustically much superior to other systems[11] such as Dolby B,[10][11][50] C,[50] dbx,[6][10] adres[10] or Super D,[10] the High Com family of systems never gained a similar market penetration. This was caused by several factors, including the existing pre-dominance of the Dolby system, with Dolby Laboratories introducing the "good enough" Dolby C update (with up to 15 dB A-weighted improvement) in 1980 as well, and also by the fact that High Com required higher quality tape decks and tapes to work with in order to give satisfactory results. High-Com II[nb 1] even required calibration of the playback level using a 400 Hz, 0 dB, 200 nWb/m[11] calibration tone for optimum results, and with prices in the several hundred dollars for the external Nakamichi compander box it was much too expensive to be used by many people outside the small group of audiophiles using high-end tape recorders or open-reel decks. When AEG-Telefunken struggled financially in 1981/1982[6] and the Hannover development site was partially disbanded and refocused on digital technologies in 1983,[6] this also put the High Com development to an end. The latest tape decks to come with High Com were produced in 1986.

Tape decks with High Com

These tape decks are known to provide built-in support for High Com:

  • Akai GX-F37[nb 12]
  • ASC AS 3000
  • Rosita Audion D 700
  • Blaupunkt XC-240, XC-1400
  • ELIN Professional Micro Component Cassette Deck - Modell TC-97
  • Eumig FL-1000µP High Com[51][nb 13]
  • Filtronic FSK-200
  • Grundig MCF 200, MCF 600, CF 5100, SCF 6200[nb 14][nb 10]
  • Hitachi D-E75 DB/SL
  • Imperial TD 6100
  • Intel Professional Micro Component Cassette Deck - Modell TC-97
  • Körting C 102, C 220
  • Revox B710 High Com[nb 15]
  • Neckermann Palladium[52]
  • Nikko ND-500H[nb 10]
  • nippon TD-3003
  • Saba CD 278, CD 362
  • Schneider SL 7270 C
  • Sencor SD-6650
  • Siemens RC 333, RC 300
  • Studer A710 High Com[53][nb 15]
  • Telefunken TC 750,[6] TC 450, TC 450M,[52] TC 650, TC 650M, STC 1 / CC 20, MC 1, MC 2, HC 800, HC 1500,[6] HC 3000, HC 750M, HC 730T, RC 100, RC 200, RC 300, Studio Center 5004, Studio Center 5005, Studio Center 7004, various[54]
  • Tensai TFL-812
  • Uher CG 321, CG 344, CG 356, mini-hit
  • Quelle Universum Senator CT 2307, Senator CT 2307A, CT 2318 (for SYSTEM HIFI 7500 SL), Senator CT 2337
  • Wangine K-3M, WSK-120, WSK-220

Other devices can be used with an external High Com compander box.

gollark: I use the arrow keys for navigating code a lot.
gollark: Various programming things.
gollark: You don't have backticks? How do you *live*?
gollark: (Three backticks then python)
gollark: ` ` ` python

See also
  • Dolby noise reduction system
  • Dolby SR (Spectral Recording)
  • dbx (noise reduction), a competing system
  • Dynamic Noise Reduction (DNR), a playback-only noise reduction system often confused with Dolby
  • CX (Compatible eXpansion by CBS)
  • FMX (broadcasting), another FM noise reduction system

Notes
  1. Telefunken's official spelling of the name was "High Com" (also as "HIGH COM"), both written with a thin space. However, Nakamichi's official spelling of their variant of Telefunken's High Com II was "High-Com II". Many independent German authors would use "High-Com" also for Telefunken's system because of a grammar feature called Durchkopplung. Compounds are concatenated without space in German. Compounds, which can't be combined without a space for linguistical reasons, are concatenated with a hyphen instead. Since High Com is a compound, the correct German spelling in normal prose would be "High-Com" despite Telefunken's alternative spelling. This holds true even more for further combinations such as "High-Com-System" (rather than "High Com-System" or "High Com System").
  2. The Nakamichi High-Com II Noise Reduction System exists in two very similar but functionally slightly different versions: One variant has a special "Disk" mode setting to decode High-Com II encoded vinyl discs without having to pass the encoded signal through a connected tape deck first, whereas the other variant makes it slightly easier to activate the 400 Hz calibration tone and allows the Subsonic and MPX input filters to be activated at the same time.
  3. Some telcom c4 companders have a "Telcom Auto" setting which would automatically activate or bypass the telcom c4 system depending on if the telcom ident tone alternating between 550 Hz and 650 Hz every 500 ms was detected on the tape leader or not.
  4. The colored tape leaders standardized (for example in "Technisches Pflichtenheft 3/9 der öffentlich-rechtlichen Rundfunkanstalten in der Bundesrepublik Deutschland") by IRT and the German public broadcasting industry indicating a record using Telefunken's telcom c4 system are defined as a sequence of 10 mm red, 20 mm white, 10 mm black and 5 mm white for 38 cm/s recordings, and 10 mm blue, 20 mm white, 10 mm black and 5 mm white for 19 cm/s. The colors must be facing the magnetizable coating / tape head side of the tape.
  5. Telefunken provided three High Com demonstration and test records labelled "High Com. Das neue Stör- und Rauschunterdrückungs-System. Von Telefunken." on ferro-magnetic (IEC type I) cassette tapes with bias 120 µs: "Eine Meß-Cassette." (64.22029): 1. Level tone 400 Hz 200 nWb/m, 2. Pink noise High Com encoded (level −30 dBeff below 200 nWb/m without compander); "Eine Demonstrations-Cassette." (64.21824), and "Eine Meß- und Demonstrations-Cassette." (64.21972): A. Calibration advice with measurement tone, B. 1. Richard Strauss Till Eulenspiegel, 2. Beethoven Wo O. 16,[*] 3. Rimsky-Korssakoff Capriccio Espagnol, 4. Schubert–Noris Serenade, 5. Studio take II[*] (Comment on sleeve: Musicians and sound engineer before recording while tuning instruments and electronics. Even the hum of a defective amplifier is audible.) [*]Telcom c4 studio material.
  6. The Telefunken TFK U401B integrated circuit was available in five revisions: TFK U401B chips with a yellow dot are equivalent to the U401BG. TFK U401BG chips with a blue dot are equivalent to the TFK U401BR. TFK U401BR chips with yellow dot as well as yellow and blue dots exist also. Yet another revision was planned to incorporate the changes to Telefunken's High Com system since about 1982 to no longer require external circuit modifications, but was apparently never released. These revisions were also used on Telefunken's own High Com modules, which were available in various assembly variants (for example BS 5335 / AT 349 355 003 or BS 5356 / AT 349 355 024) and also used in many third-party products.
  7. In 1979, Nakamichi, in cooperation with Three Blind Mice Records, Inc., offered a High-Com II demonstration tape S 008 / T-480305, a limited edition not-for-sale High Com II encoded audiophile cassette tape sample recorded at 4.8 cm/s (1-7/8 ips) on a Nakamichi Metalloy Direct Cassette ZX C-15 with Fuji IEC type-IV metal tape with bias 70 µs. The tracks included on side A: 1. Little Step (Masaru Imada Quartet), 2. New Orleans Sunday (Shōji Yokouchi Trio & Yuri Tashiro), side B: ?.
  8. Track list of Nakamichi High-Com II demonstration record NAK-100: Side A: Philharmonia Hungarica (Zoltan Rozsnyai): 1. Bizet (Carmen prelude) [2:30] 2. Berlioz (Rákóczi March from Damnation of Faust) [4:40] 3. Rimsky-Korsakov (Procession of the Nobles from Mlada) [4:55] 3. Brahms (Hungarian Dance No. 5) [4:30] 4. 400 Hz calibration tone. [1:00], Side B: S.M.A. Sextet (Sherman Martin Austin): 1. Impressions (John Coltrane) [5:00] 2. Mimosa (Dennis Irwin) [5:52] 3. Little B's Poem (Bobby Hutcherson) [3:12] 4. 400 Hz calibration tone [1:00].
  9. Rotel's High Com companders RN-500 and RN-1000 used other time constants than Telefunken's High Com, thereby rendering the encoded material incompatible with other High Com companders. Early Rotel units internally used Telefunken High Com modules with two parts exchanged (R7 = 3.3 MΩ instead of 8.2 MΩ, C7 = 33 µF / 16 V instead of 0.22 µF / 16 V), whereas later units used their own circuitry.
  10. Not all OEMs followed the Telefunken's High Com specifications rigorously. Besides Rotel's changes of the time constants, Grundig and Nikko also introduced changes to the circuitry.
  11. The companders Aster Dawn Stereo Compander SC 505 and Starsonic High-Com Noise Reduction System DL 506 were developed by Quirino Cieri, manufactured by two art shops and distributed through Diemme Sonic and D.A.A.F., both residing at Jacopo Palma 11, Milano, Italy at the time. Both companders were available in black and silver case finish.
  12. The High Com module for the Akai GX-F37 was named BA-T2017A050A (CL-5602) and contained two Telefunken TFK U401BR chips.
  13. The Eumig FL-1000µP was alternatively available with either the Dolby NR (type B) or the Telefunken High Com noise reduction system and corresponding front plates.
  14. The High Com module for one Grundig tape deck was named KPL-39302-942 / 39302-946 and contained one Telefunken TFK U401BR chip.
  15. The Studer A710 was alternatively available with either Telefunken High Com and DNR (PCB 1.710.483-00 + 1.710.493-00 each based on two TFK U401BR), or with Dolby B and C (PCB 1.710.489-00 + 1.710.492-00 each based on two HA 12038) noise reduction modules and front plates. Likewise, the very similar Revox B710 was alternatively available in High Com and Dolby B versions, but could be factory-upgraded to support both, Dolby B and C after the release of the Revox B710 Mk II model, which featured Dolby B and C only as well.

References
  1. Webers, Johannes (1989). "E.2.4.2 Das Telcom-System: Der "telcom c4"-Kompander / Das High-Com-System". Tonstudiotechnik: Schallaufnahme und -wiedergabe bei Rundfunk, Fernsehen, Film und Schallplatte. Franzis Handbuch (in German) (5th extended ed.). Munich, Germany: Franzis-Verlag GmbH. pp. 329–334. ISBN 3-7723-5525-0. (758+2 pages)
  2. Peissig, Jürgen; ter Haseborg, Jan Remmer; Keiler, Florian; Zölzer, Udo (2004-10-05). "Digital Emulation of Analog Companding Algorithms for FM Radio Transmission" (PDF). Proceedings of the 7th International Conference on Digital Audio Effects (DAFx'04). Naples, Italy: 285–290. Archived (PDF) from the original on 2017-11-14. Retrieved 2017-11-14.
  3. Copeland, Peter (February 2009) [September 2008]. Redlich, Gert (ed.). "Manual of Analoque Sound Restoration Techniques". London, UK: The British Library Sound Archive (www.bl.uk). Chapter 9. Reciprocal noise reduction. Archived from the original on 2017-11-05. Retrieved 2017-11-05 – via Deutsches Hifi-Museum, Wiesbaden, Germany. (NB. Copeland was strongly biased from a British perspective, but nevertheless very knowledgeable.)
  4. Nakamichi High-Com II Noise Reduction System - Owner's Manual - Bedienungsanleitung - Mode d'Emploi (in English, German, and French). 1980. 0D03897A, O-800820B. Archived from the original on 2017-11-10. Retrieved 2017-11-10.
  5. "High Com - the latest noise reduction system / Noise reduction - silence is golden" (PDF). elektor – up-to-date electronics for lab and leisure. Vol. 1981 no. 70. Elektor Publishers Ltd. February 1981. pp. 2-04–2-09. ISSN 1757-0875. Archived (PDF) from the original on 2020-07-02. Retrieved 2020-07-02. (6 pages)
  6. Schröder, Ernst F. "The Story of HIGH COM". Archived from the original on 2016-04-16. Retrieved 2016-04-16.
  7. Schröder, Ernst F. (1980). "HIGH COM - The HIGH COM broadband compander utilizing the U401BR integrated circuit" (PDF). Semiconductor information. AEG-Telefunken. 80 (2). 2.80. Archived (PDF) from the original on 2016-04-16. Retrieved 2016-04-16.
  8. Heiliger, Jürgen (2011-08-18). "Telefunken CN 750 High Com" (in German). Archived from the original on 2017-12-08. Retrieved 2017-12-08.
  9. Friedrich, Hans Jörg (2008). "(II.) 11.2.2. Aufnahme- und Übertragungstechnik: Die Schallplatte". Written at Stuttgart, Germany. Tontechnik für Mediengestalter: Töne hören - Technik verstehen - Medien gestalten. X.media.press (in German) (1 ed.). Berlin / Heidelberg, Germany: Springer-Verlag. p. 164: Table 11.1. doi:10.1007/9783540718703. ISBN 978-3-540-71869-7. ISSN 1439-3107. Retrieved 2020-07-04. […] schwarz-weiß-rot […] Stereo […] 15 Zoll/Sekunde […] Rauschunterdrückung Telcom C4 […] (xvii+346 pages) (NB. The cited tape leader colors are not necessarily correct, since other sources cite the pattern black-white-red as for 15 inch/s stereo with timecode.)
  10. Kamm, Dieter; Pütz, Jean (March 1980). Reis, Brigitte; Praßer, Gerhard (eds.). "High-Com, Hobby-Com - Für Hifi-Freunde: Musikgenuss ohne Rauschen" [High-Com, Hobby-Com - For Hi-Fi fans: Enjoying music without noise] (PDF). Hobbytip der Hobbythek (in German). WDR. 56. Archived (PDF) from the original on 2017-11-05. Retrieved 2017-11-05.
  11. The Stillness of Dawn - High-Com II Demonstration Record (A limited edition not-for-sale High Com II encoded audiophile vinyl record and corresponding leaflet. This LP contains 400 Hz, 0 dB, 200 nWb/m calibration tones as well.). Nakamichi. 1979. NAK-100. Quotes from the sleeve: […] Thousands of man-hours were spent listening, adjusting, optimizing—until harpsichords sound like harpsichords without mutilated transients, until bass viols sound like bass viols without harmonic distortion, until triangles sound lean and crisp without breathiness. The result is High-Com II, the world's finest two-band noise-reduction system. […] High-Com II is the first audiophile noise-reduction system that achieves professional quality. […] Listen especially for the dramatic reduction in surface noise on this High-Com II encoded record. There is no residual hiss; the ticks, pops, and crackles that mar conventional discs are absent. So is turntable rumble. The loud passages emerge with unprecedented clarity since they need not be recorded at so high and distortion-producing a level. […] Between programs, there is utter silence. […] We also suggest you listen closely for sounds of "breathing" and noise pumping. This common fault of noise-reduction systems has been eliminated in High-Com II. Listen also to High-Com II's remarkable ability to accurately preserve musical transients. They are neither muted nor exaggerated nor edgy as with other companders. This accuracy of reproduction—on all types of music, at all frequencies, and at all levels—is what distinguishes High-Com II from other noise-reduction systems. […] Unlike simple companders, High-Com II is optimized differently for signals of different strength and different frequencies. Low-level signals are processed for maximum noise reduction, high-level ones for minimum distortion. This sophisticated technique assumes maximum dynamic range with minimum "breathing" and other audible side effects. […] Sound of extraordinary dynamic range—a background free from surface noise, pops, clicks, rumble, and groove echo—the mightiest crescendo, free from distortion. Sound without breathing, pumping, or other ill side effects. (NB. For the track list see here.)
  12. Datenblatt U401B High-Com (in German). AEG-Telefunken. S8/V2.711/0279AI.
  13. Wiedenroth, Bernd (1982). "High-Com-Modifikationen" [High Com modifications]. Funkschau (in German). Vol. 1982 no. 26. p. 69. Archived from the original on 2017-11-05. Retrieved 2017-11-05.
  14. Benn, Dietrich (January 1982). "(unknown)". stereoplay (in German). No. 1.
  15. Höppner, Dietrich; Hintzmann, Kurt D.; Schröder, Ernst F. (1979). "Monolithisch integrierte NF-Kompander". Wissenschaftliche Berichte. AEG-TELEFUNKEN. 52 (1–2): 97–104.
  16. Schröder, Ernst F. (1979). "2-Band und 3-Band Kompander nach dem Kettenverstärkerprinzip (HIGH COM II und HIGH COM III)". Laborbericht (in German). Telefunken Fernseh- und Rundfunk GmbH.
  17. "Nakamichi High-Com II". Stereo (in German). Vol. 1979 no. 11. November 1979.
  18. "Nakamichi High-Com II". Audio (in German). Vol. 1979 no. 12. December 1979.
  19. "Nakamichi High-Com II". KlangBild (in German). 1981 (06). June 1981.
  20. Mielke, E.-Jürgen (1977). "Einfluß des Dolby-B-Verfahrens auf die Übertragungsqualität im UKW-Hörrundfunk" [Influence of Dolby B system on the quality of transmission in FM radio broadcasting]. Rundfunktechnische Mitteilungen (RTM) (in German). Institut für Rundfunktechnik (IRT). 21: 222–228.
  21. "High-Com bei MW-Übertragung". Funkschau (in German). Vol. 1982 no. 22. 1982. pp. 61–.
  22. Prüfung eines modifizierten HIGH COM-Kompanders für den Einsatz bei der RF-Übertragung im UKW-Hörfunk [Evaluation of a modified HIGH COM compander for usage in the RF transmission in FM radio broadcasting] (in German). Institut für Rundfunktechnik (IRT). 1981-12-30. Technical Report 55/81.
  23. "High-Com im Rundfunk: Empfang verbessern". Funkschau (in German). Vol. 1983 no. 17. 1983. pp. 50–.
  24. Porges, Ivan; Schröder, Ernst F. (1983). "Ein kompatibles Kompandierungsverfahren für FM-Rundfunk und dessen schaltungstechnische Realisierung". Hörrundfunk. NTG-Fachberichte #83 (in German). Berlin / Offenbach, Germany: Nachrichtentechnische Gesellschaft (NTG) / Verband Deutscher Elektrotechniker (VDE) (6): 151–158.
  25. "High-Com im Rundfunk: Plädoyer für den Feldversuch". Funkschau (in German). Vol. 1983 no. 25. 1983. pp. 44–.
  26. "High-Com FM; Großversuch". Funkschau (in German). Vol. 1983 no. 26. 1983. pp. 11–.
  27. "High-Com-FM-Decoder für High-Com-FM-Feldversuch". Funkschau (in German). Vol. 1984 no. 3. 1984. pp. 74–.
  28. "Rundfunktechnik: High-Com-FM-Feldversuch - Anmerkungen". Funkschau (in German). Vol. 1984 no. 8. 1984. pp. 69–.
  29. "Rundfunk - Singende Säge". Der Spiegel (in German). Vol. 1984 no. 23. 1984-06-04. pp. 76, 78. Archived from the original on 2020-07-01. Retrieved 2020-07-01. (2 pages)
  30. Ganser, Otto (1984-02-03). "High-Com-UKW: Bericht von Otto Ganser über den ARD-Versuch". BNL-Radioshow (broadcasting) (in German) (82). [6:20 min]
  31. "Hörfunk weiterhin ohne High Com". ORF Technikum – Fortbildungsdienst für alle Technikbereiche. Aktuelles aus dem In- und Ausland (in German). Österreichischer Rundfunk (ORF), Generalintendanz / Schulung und Dokumentation. 1984 (9). October–November 1984.
  32. "1. Studio- und Außenübertragungstechnik – 1.1. Hörfunk". Geschäftsbericht 1984 – Geschäftsbericht des Bayerischen Rundfunks 1984 (PDF) (in German). Bayerischer Rundfunk (BR). 1984. p. 46. Archived (PDF) from the original on 2020-07-02. Retrieved 2020-07-02. […] Die Ausstrahlungsversuche mit dem Rauschunterdrückungsverfahren High Com FM wurden abgeschlossen. In den vergangenen Jahren hatten sich die deutschen Rundfunkanstalten intensiv mit diesem Systemvorschlag zur Verminderung des Rauschens auf dem Funkübertragungswege zwischen UKW-Sender und Rundfunkteilnehmer beschäftigt. Insbesondere das Institut für Rundfunktechnik in München stellte umfangreiche Untersuchungen dazu an. Auch die Betriebsleiterkonferenzen der Rundfunkanstalten für die Bereiche Hörfunk und Sendertechnik beteiligten sich eingehend an den entsprechenden Überlegungen und Betrachtungen. Die ursprüngliche Erwartung, mit dem System High Com FM Qualitätsverbesserungen im UKW-Hörfunk sowie eine Verbesserung der Übertragungstechnik in den Versorgungsrandgebieten erreichen zu können, bestätigte sich nicht im gewünschten Ausmaß. Die Technische Kommission von ARD und ZDF legte daraufhin fest, dieses Rauschunterdrückungsverfahren nicht einzuführen. Dieser Entscheidung war ein ausgiebiger bundesweiter Feldversuch in den ersten drei Monaten des Jahres 1984 vorangegangen, an dem auch der Bayerische Rundfunk mit einer UKW-Senderkette teilnahm. […]
  33. "Rotel High Com Noise Reduction System RN-1000 RN-500 - owner's manual" (PDF). pp. 1–7. Archived (PDF) from the original on 2017-11-14. Retrieved 2017-11-14.
  34. "13° SIM - High Fidelity 1979" (PDF). Discoteca Hi-Fi (Report) (in Italian). Milano, Italy. October 1979. Archived (PDF) from the original on 2013-10-21. Retrieved 2020-07-02. (2 pages)
  35. Diemme Sonic. "Poco rumore a poco" (PDF) (in Italian). Milano, Italy. Archived (PDF) from the original on 2013-10-21. Retrieved 2020-07-02 – via Sito web personale di Quirino Cieri.
  36. Diemme Sonic. "High Com - Arriva L'Aster Down" (PDF). SuperStereo. Notizie (in Italian). Milano, Italy. Archived (PDF) from the original on 2013-10-21. Retrieved 2020-07-02 – via Sito web personale di Quirino Cieri. (NB. The title contains a typo and should read "High Com - Arriva L'Aster Dawn" instead.)
  37. Diemme Sonic (May 1980). "Italiano, economico, separato, High-Com" (PDF). Suono (in Italian) (93). Milano, Italy. Archived (PDF) from the original on 2020-07-02. Retrieved 2020-07-02 – via Sito web personale di Quirino Cieri.
  38. "nei tuoi nastri musica+dinamica (senza fruscio) - Compandea Starsonic High Com DL 506". Discoteca Hi-Fi (Advertisement) (in Italian). Milano, Italy. May 1981. Archived from the original on 2020-07-02. Retrieved 2020-07-02. (1 page)
  39. Sellaria, Marco (1981). "Compander stereo STARSONIC DL506" (PDF). cq elettronica - speciale prove OM e CQ - supplemento omaggio al n. 169 di cq elettronica (in Italian). No. 1. Bologna, Italy. p. 59. No. 169. Archived (PDF) from the original on 2016-09-11. Retrieved 2020-07-02.
  40. Cossa, Piero. "Gli Optionals Starsonic" (PDF) (Review). Accessori (in Italian). pp. 22–23, 24?. Archived (PDF) from the original on 2013-10-21. Retrieved 2020-07-02 – via Sito web personale di Quirino Cieri. Cite magazine requires |magazine= (help) (3 pages)
  41. "Hobbycom (High-Com): Testbericht". Funkschau (in German). Vol. 1980 no. 13. 1980. pp. 97–.
  42. "the High Com noise reduction system" (PDF). elektor – up-to-date electronics for lab and leisure. Vol. 1981 no. 71. Elektor Publishers Ltd. March 1981. pp. 3-06–3-17. ISSN 1757-0875. Archived (PDF) from the original on 2020-07-02. Retrieved 2020-07-02. (12 pages)
  43. "Rauschunterdrückung - der Physik ein Schnippchen schlagen! (HighCom, Prinzip)". elektor (in German). Vol. 1981 no. 2. Elektor Verlag GmbH. February 1981. pp. 24–. ISSN 0932-5468. CODEN ELKRCM.
  44. "Elektor Hi-Fi-Kompander: Rauschen - ade! (2 HighCom-Module U401BR)". elektor (in German). Vol. 1981 no. 3. Elektor Verlag GmbH. March 1981. pp. 56–. ISSN 0932-5468. CODEN ELKRCM.
  45. "Nachtrag HiFi Kompander". elektor (in German). Vol. 1981 no. 4. Elektor Verlag GmbH. April 1981. pp. 58–. ISSN 0932-5468. CODEN ELKRCM.
  46. "Elektor HiFi-Kompander: Monitor - Hinterbandkontrolle für Drei-Kopf-Geräte". elektor (in German). Vol. 1982 no. 1. Elektor Verlag GmbH. January 1982. pp. 1-30 – 1-??. ISSN 0932-5468. CODEN ELKRCM.
  47. "Amtron - Kits elettronici" (PDF). elektor – elettronica - scienza tecnica e diletto (Advertisement) (in Italian). Vol. 1981 no. 22. Jacopo Castelfranchi Editore (JCE). March 1981. p. 3-13. Archived (PDF) from the original on 2020-07-12. Retrieved 2020-07-12.
  48. "Amtron micro line High-Com System UK 512". 1983 [1982]. Archived from the original on 2020-07-02. Retrieved 2020-07-02. (NB. Advertised in 1982/1983 Amtron catalog in Italy.)
  49. "Riduttore Di Fruscio High-Com System UK 512 W". Amtron Kuriuskit - kits elettronici 1982–83 (PDF) (Catalog) (in Italian). 17. Milano, Italy: G.B.C. Amtron. 1983 [1982]. pp. 2, 10. Archived (PDF) from the original on 2017-08-13. Retrieved 2020-07-12. […] Tensione di funzionamento: 18V […] Corrente di funzionamento: 80 mA […] Banda passante: 40 Hz + 17 kHz […] Resistenza d'ingresso: * compressione: 5,6 KΩ * espansione: 50 KΩ […] Resistenza d'uscita in espansione: 5 KΩ […] Rapporto S/N ingresso AMP: 80 dB […] Sensibilità d'ingresso DIN: 0,2 mV/per ogni KΩ d'ingresso […] Riduzione di fruscio: 20 dB […] Distorsione totale: < 0,1% a 1 kHz […] SM/1512-07 […]
  50. Bruch, Walter (1983). "Von der Tonwalze zur Bildplatte (Teil II) - Entwicklung der Magnetbandtechnik". Funkschau. 100 Jahre Ton- und Bildspeicherung (in German). No. 18, 19, 20, 21. Archived from the original on 2017-12-08. Retrieved 2017-12-08.
  51. Eumig FL1000µP Cassettendeck - Die Cassetten-Tonbandmaschine (Product flyer) (in German). 939.540/4. Archived from the original on 2017-11-13. Retrieved 2017-11-13.
  52. "Frei Haus". Audio (in German). November 1980. Archived from the original on 2017-11-13. Retrieved 2017-11-13.
  53. Studer A710 Professional Cassette Tape Recorder - Service-Anleitung - Service Instructions - Instructions de service (PDF) (in German, English, and French). 1984 [1980]. Archived (PDF) from the original on 2015-12-11. Retrieved 2019-08-13.
  54. "Telefunken TC 750 - HiFi Stereo Recorder - 1979 - 1981". Archived from the original on 2017-11-05. Retrieved 2017-11-05.

Further reading
  • Wermuth, Jürgen; Temmer, Stephan F. (1975). "Dynamikerweiterung durch neuartigen Studio-Kompander" [Dynamic expansion through novel studio compander]. Funkschau (in German). Vol. 1975 no. 18. pp. 103–106? / 571–. (NB. This article mixes up the Dolby curve.)
  • Wermuth, Jürgen (1975-11-22) [1975-11-19]. Dynamik-Erweiterung durch neuartigen Studio-Kompander [Dynamic expansion through novel studio compander]. 10. Tonmeistertagung (in German). Köln, Germany.
  • Schröder, Ernst F.; Wermuth, Jürgen (1976-10-05). "Ein neues Kompandersystem – Grundlagen und Einsatzmöglichkeiten" [A new compander system - Basics and applications]. Fernseh- und Kinotechnik (FKT) (Speech at the FKTG Tagung) (in German). Vol. 30 no. 12. Freiburg, Germany. pp. 9–11.
  • Dickopp, Gerhard; Schröder, Ernst F. (1978). "Der Telefunken-Kompander" [The Telefunken compander]. Rundfunktechnische Mitteilungen (RTM) (in German). 22 (2): 17–28 / 63–74.
  • Dickopp, Gerhard; Schröder, Ernst F. (1978). "Meßverfahren für Kompander" [Measurement technologies for companders]. Funkschau (in German). Vol. 50 no. 17. pp. 29–32.
  • Schröder, Ernst F.; Wermuth, Jürgen (1978-07-13), Circuit system for the generation of a direct control voltage which is dependent on an alternating voltage, DE2830784, US4321482
  • Scholz, Werner (1978-12-23), Schaltung zur wahlweisen automatischen Dynamikkompression oder -expansion, DE2856045
  • Dickopp, Gerhard; Schröder, Ernst F. (April 1979). "HIGH COM - Ein Kompander von Telefunken". Telefunken Firmenschrift (in German). Telefunken.
  • Schröder, Ernst F. (1979-05-12), Schaltung zur wahlweisen automatischen Dynamikkompression oder -expansion, DE2919280
  • "Das neue Rausch- und Störunterdrückungssystem von Telefunken. Ein Meilenstein in der High-Fidelity.". Telefunken Report '79–80 - HiFi-Anlagen, Radio-Rekorder, Heimradios (Product catalog) (in German). Telefunken. 1979. p. 28. E-Nr. 370381235. Archived from the original on 2020-07-02. Retrieved 2020-07-02.
  • "High-Com für Profis". Funkschau (in German). Vol. 1980 no. 14. 1980. pp. 81–.
  • Wiedenroth, Bernd (1980). "High-Com - Überblick und Entwicklungsstand". Funkschau (in German). Vol. 1980 no. 17. pp. 67–71.
  • Schröder, Ernst F. (Summer 1980). Dynamikkompander - Stand und Ausblick (in German). Nachrichtentechnisches Kolloqium im Fachbereich Elektrotechnik der Universität Duisburg.
  • Roberson, Howard A. (1980). "Nakamichi High-Com II Noise-Reduction System". Audio. Equipment profiles. No. 9. pp. 62–66.
  • Schröder, Ernst F. (1980). "A New Integrated Audio Compansion System". Proceedings of the Forth European Conference on Electronics (Eurocon '80). Stuttgart, Germany: 612–614.
  • Höppner, Dietrich; Schröder, Ernst F. (October 1980). "HIGH COM - ein Kompander zur breitbandigen Geräuschunterdrückung". Technische Rundschau (in German) (41).
  • "Das neue Rausch- und Störunterdrückungssystem von Telefunken. Ein Meilenstein in der High-Fidelity.". Telefunken High Fidelity Programm '80–81 (Product catalog) (in German). Telefunken. 1980. p. 4. E-Nr. 318391519. Archived from the original on 2020-07-02. Retrieved 2020-07-02.
  • "Kompandersystem; Dolby C kontra High Com". Funkschau (in German). Vol. 1981 no. 7. 1981. pp. 76–.
  • "HIGH COM". Audio Engineering. 1981 (3): 30–35. 1981.
  • Schröder, Ernst F. (1981). Kompatibilität von Konsumgeräte-Kompandern zur Geräuschunterdrückung. 1. Tonmeistertagung (Report) (in German). Munich, Germany. pp. 295–301.
  • Ratzki, Werner (1982). "Einbau eines Kompanders (Kompander-Einbau: Erfahrungen mit High-Com-Baustein)". Funkschau (in German). Vol. 1982 no. 16. pp. 57–. Archived from the original on 2020-07-11. Retrieved 2020-07-01.
  • "Rauschkiller: Dolby- und High-Com-Rauschminderung - Teil 1". Funkschau (in German). Vol. 1983 no. 3. 1983. pp. 76–. Part 1, "Rauschkiller: Dolby- und High-Com-Rauschminderung - Teil 2". Funkschau (in German). Vol. 1983 no. 4. 1983. pp. 82–. Part 2, "Rauschkiller: Dolby- und High-Com-Rauschminderung - Teil 3". Funkschau (in German). Vol. 1983 no. 5. 1983. pp. 80–. Part 3.
  • Telefunken U401BR. Archived from the original on 2017-11-14. Retrieved 2017-11-14.
  • Schröder, Ernst F. (1989-07-07). Beitrag zur Analyse und zur Dimensionierung von Kompandern anhand einer einheitlichen Beschreibungsweise [Contribution to Analysis and Dimensioning of Companders by utilizing a Unified Description] (PDF) (PhD thesis) (in German). Archived (PDF) from the original on 2020-05-29. Retrieved 2017-11-15.
  • Görne, Thomas (2006). Schmidt, Ulrich (ed.). Tontechnik [Audio technology] (in German) (1 ed.). Leipzig, Germany: Carl Hanser. ISBN 3-446-40198-9.
  • Schleef, Daniel (July 2004). Akustisch-klangliche Optimierung digitaler Audio-Kompandersysteme für drahtlose Mikrofonanlagen (PDF) (Diploma thesis) (in German). Erich-Thienhaus-Institut der Hochschule für Musik Detmold / Sennheiser electronic GmbH & Co. KG. Archived (PDF) from the original on 2020-07-03. Retrieved 2020-07-03.
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