Editing Cassette deck (section)

=== Performance improvements and additional features ===
[[File:Revox B215 cassette deck (crop).jpg|thumb|Revox B 215, 4-motor-cassette deck without belts (direct drive, 1985–1992)]]
[[File:Nakamichi Dragon - High End Cassette Deck with Auto Reverse.jpg|thumb|[[Nakamichi Dragon]] cassette deck with azimuth adjustment 1983 - 1993, 1995 (Last Edition)]]
Cassette decks reached their pinnacle of performance and complexity by the mid-1980s. {{Citation needed|date=December 2017}} Cassette decks from companies such as [[Nakamichi]], [[Revox]], and [[Tandberg]] incorporated advanced features such as multiple [[tape head]]s and dual [[capstan (tape recorder)|capstan]] drive with separate reel motors. Auto-reversing decks became popular and were standard on most factory installed automobile decks.

==== Integrated noise reduction systems - Dolby B, C, and S ====
[[File:Harman Kardon TD4800-130311-0014EC (cropped).jpg|thumb|Dolby S cassette deck by harman/kardon (1990)]] 
The [[Dolby noise reduction system|Dolby B noise reduction system]] was key to realizing low noise performance on the - compared to reel-to-reel-technology - relatively slow and narrow cassette tapes. It works by boosting the high frequencies on recording, especially low-level high-frequency sounds, with corresponding high frequency reduction on playback. This lowers the high frequency noise (hiss) by approximately 9&nbsp;dB. Enhanced versions included [[Dolby C]] (from 1980) and [[Dolby S]] types. Of the three, however, only Dolby B became common on automobile decks.<ref>[https://fonoforum.de/archiv?tx_archive_pi1%5Baction%5D=download&tx_archive_pi1%5Barticle%5D=17754&tx_archive_pi1%5Bcontroller%5D=Archive&cHash=9aa9b2bbd41d9f64be1ff21632d57fd8 fonoforum.de 8/1991, Testreport Dolby-S-Kassettendeck] {{Webarchive|url=https://web.archive.org/web/20200412073132/https://fonoforum.de/archiv?tx_archive_pi1%5Baction%5D=download&tx_archive_pi1%5Barticle%5D=17754&tx_archive_pi1%5Bcontroller%5D=Archive&cHash=9aa9b2bbd41d9f64be1ff21632d57fd8 |date=2020-04-12 }} (German; PDF, 2 MB)</ref>

==== Three heads for realtime monitoring of recordings and improved sound quality ====
Three-head technology uses separate heads for recording and playback (the third of the three heads being the erase head). 
This allows different record and playback head gaps to be used. 
A narrower head gap is optimal for playback than for recording, so the head gap width of any combined record/playback head must necessarily be a compromise.  
Separate record and playback heads also allow off-the-tape monitoring during recording, permitting immediate verification of the recording quality. 
(Such machines can be identified by the presence of a ''monitor'' switch with positions for ''tape'' and ''source'', or similar.) 
Three-head systems were common on reel-to-reel decks, but were more difficult to implement for cassettes, 
which do not provide separate openings for record and play heads. 
Some models squeezed a monitor head into the capstan area, and others combined separate record and playback gaps into a single headshell.

==== Auto reverse for automated sequential playback of both cassette sides ====
In later years, an ''auto-reverse'' feature appeared that allowed the deck to play (and, in some decks, record) on both sides of the cassette without the operator having to manually remove, flip, and re-insert the cassette. 
Most auto-reverse machines use a four-channel head (similar to those on multitrack recorders), with only two channels connected to the electronics at one time, one pair for each direction. 
Auto-reverse decks employ a capstan and pinch roller for each side. 
Since these use the same opening in the cassette shell normally used for the erase head, 
such decks must fit the erase head (or two, one for each direction) into the center opening in the shell along with the record/play head.

In later auto-reverse machines, the ''auto reverse'' mechanism uses an ordinary two-track, quarter-width head, 
but operates by mechanically rotating the head 180 degrees so that the two head gaps access the other tracks of the tape. 
There is usually an azimuth adjustment screw for each position. 
Nevertheless, due to the repeated movement, the alignment (in particular, the azimuth) deviates with usage. 
Even in a machine with a four-channel head, slight asymmetries in the cassette shell make it difficult to align the 
head perfectly for both directions. {{Citation needed|date=March 2012}}

[[File:Nakamichi RX-505 autoreverse cassette deck.jpg|thumb|Nakamichi RX series RX-505 deck]]
[[File:Nakamichi RX 505 Top Open1.jpg|thumb|RX-505 auto reverse mechanism]]

In one machine, the Dragon, Nakamichi addressed the issue with a motor-driven automatic head alignment mechanism. 
This proved effective but very expensive. 
Later Nakamichi auto-reverse models, the RX series, was essentially a single-directional deck, 
but with an added mechanism that physically removed the cassette from the transport, flipped it over, and re-inserted it. 
Akai made a similar machine but with the mechanism and cassette laid out horizontally instead of upright.
This permitted the convenience of auto-reverse with little compromise in record or playback quality.{{Citation needed|date=March 2012}}

==== Integration of digital electronics, from the 1980s ====
As a part of the [[Digital Revolution]], the ongoing development of electronics technology [[Moore's Law|decreased the cost of digital circuitry]] to the point that the technology could be applied to consumer electronics. The application of such [[digital electronics]] to cassette decks provides an early example of [[mechatronic]] design, which aims to enhance mechanical systems with electronic components in order to improve performance, increase system flexibility, or reduce cost.<ref>{{cite book |last=van Amerongen |first=Job |editor-last=Bishop |editor-first=Robert H. |title=Mechatronics: An Introduction |publisher=CRC Press |date=2005 |page=12.1 |chapter=Chapter 12: The Role of Controls in Mechatronics |isbn=978-1-4200-3724-1|url=https://books.google.com/books?id=CTfQPQRooMgC}}</ref> The inclusion of [[Logic gate|logic circuitry]] and [[solenoid]]s into the transport and control mechanisms of cassette decks, often referred to ''logic control'', contrasts with earlier ''piano-key'' transport controls and mechanical linkages. One goal of using logic circuitry in cassette decks or recorders was to [[Error-tolerant design|minimize equipment damage upon incorrect user input]] by including [[fail-safe]]s into the transport and control mechanism.<ref>{{cite patent | country = United States | number = 3347996 A | title = Control system for a magnetic recorder | pubdate = 1967-10-17 | fdate = 1963-10-25 | pridate = 1962-10-27 | inventor = Goji Uchikoshi | url = https://www.google.com/patents/US3347996}} "By the provision of a logical circuit in the control circuit for a magnetic recorder, even when the keys of the key board are actuated in any desired sequence, the magnetic recorder and its associated devices can be promptly and precisely controlled without causing any damages thereon."</ref> Such fail-safe behavior was described in a review by [[Julian Hirsch]] of a particular cassette deck featuring logic control.<ref>{{cite magazine |last1= Hirsch |first1= Julian|author-link1=Julian Hirsch |date= May 1979 |title=Eumig 'CCD' Cassette Deck |url=http://www.americanradiohistory.com/Archive-Poptronics/70s/1979/Poptronics-1979-05.pdf  |magazine=[[Popular Electronics]] |access-date=18 December 2017 |quote=The transport controls are fully logic operated through solenoids. Any transport control button can be touched while the machine is running in any mode without risking damage to tape or deck. Even the button for the cassette compartment door can be operated while the tape is running. |pages=39–44}}</ref> Some examples of fail-safe mechanisms incorporated into logic control decks include: a mechanism designed to protect internal components from damage when the tape or motor is locked, a mechanism designed to prevent the tape from being wound improperly, among others.<ref>{{cite journal |last1= Takahata |first1= Masato |last2= Michinaka |first2= Takashi |last3= Goto |first3= Tsutomu |last4= Igawa |first4= Yoshihisa |last5= Arai |first5= Kenboku |last6= Takata |first6= Masanao |display-authors=1|date= 1991|title= Logic Controlled Cassette Deck Mechanism "DK-76" |url= https://www.denso-ten.com/business/technicaljournal/pdf/4-5E.pdf|journal= Fujitsu Ten Technical Journal |issue= 4|pages= 52–60|access-date= 2017-12-12}}</ref> Some logic control decks were designed to incorporate light-touch buttons or [[remote control]], among other features marketed as being convenient.<ref>{{cite magazine |last1= Hirsch |first1=Julian |author-link1=Julian Hirsch |date= May 1979 |title=Aiwa Model AD-6900 cassette deck |url=http://www.americanradiohistory.com/Archive-Poptronics/70s/1979/Poptronics-1979-09.pdf  |magazine=[[Popular Electronics]] |access-date=18 Dec 2017 |quote=There was a slight "clunk" from the solenoids as they operated, but the buttons themselves required almost no activating pressure, and the control logic appeared to be as foolproof as claimed. |pages=28–31}}</ref><ref>{{cite web |url=http://www.ant-audio.co.uk/Tape_Recording/JVC/JVC_Cassette_Decks__1982_LR.pdf |title= JVC Stereo Cassette Decks |date=1982 |publisher=Victor Company of Japan |access-date= 2017-12-13|quote= "The following conveniences are available: *Direct change of mode... *Light-touch button... *Punch-in recording... *Remote control..."}}</ref> In the [[car stereo]] industry, full logic control was developed with the aim of [[miniaturization]], so that the cassette deck would take up less dashboard space.<ref>{{cite journal |last1= Takai |first1= Kazuki |date= 1985-02-01|title= Ultra-Compact, Full-Logic Cassette Mechanism|url= http://papers.sae.org/850024/|journal= SAE Technical Paper 850024|series= SAE Technical Paper Series |volume= 1 |pages= 20|doi= 10.4271/850024|access-date= 2017-12-13|url-access= subscription}}</ref>

==== Dolby HX Pro for higher recording levels on the same tape material ====
[[Bang & Olufsen]] developed the [[HX Pro]] headroom extension system in conjunction with [[Dolby Laboratories]] in 1982. This was used in many higher-end decks. HX Pro reduces the high-frequency bias during recording when the signal being recorded has a high level of high frequency content. Such a signal is self-biasing. Reducing the level of the bias signal permits the desired signal to be recorded at a higher level without saturating the tape, thus increasing [[Headroom (audio signal processing)|headroom]] or maximum recording level.

Some decks incorporated microprocessor programs to adjust tape bias and record level calibration automatically.

==== Advances in tape materials ====
New tape formulations were introduced. 
[[Chromium dioxide]] (referred to as CrO<sub>2</sub> or Type II) was the first tape designed for extended high-frequency response, but it required higher bias. Later, as the IEC Type II standard was defined, a different equalization settings was also mandated to reduce hiss, thus giving up some extension at the high end of the audio spectrum. 
Better-quality cassette recorders soon appeared with a switch for the tape type. 
Later decks incorporated coded holes in the shell to autodetect the tape type. 
Chromium dioxide tape was thought to cause increased wear on the heads, so TDK and Maxell adapted cobalt-doped ferric formulations to mimic CrO<sub>2</sub>. 
Sony briefly tried FerriChrome (Type III) which claimed to combine the best of both; some people, however, stated that the reverse was true because the Cr top layer seemed to wear off quickly, reducing this type to Fe in practice. Most recent decks produce the best response and dynamic headroom with metal tapes (IEC Type IV) which require still higher bias for recording, though they will play back correctly at the II setting since the equalization is the same.

==== Effects achieved by the technological developments ==== 
With all of these improvements, the best units could record and play the full audible spectrum from 20&nbsp;Hz to over 20&nbsp;kHz (although this was commonly quoted at -10, -20 or even -30&nbsp;dB, not at full output level), with [[wow (recording)|wow and flutter]] less than 0.05% and very low noise. A high-quality recording on cassette could rival the sound of an average commercial CD, though the quality of pre-recorded cassettes has been regarded by the general public as lower than could be achieved in a quality home recording.<ref name=FORUM1>{{cite news|title=Prerecorded cassette quality?|website=AudioKarma.org|type=Forum|date=2005-09-05}}</ref> There was a call for better sound quality in 1981, surprisingly by the head of [[Tower Records]], Russ Solomon. At a meeting of the [[National Association of Recording Merchandisers]] (NARM) Retail Advisory Committee in [[Carlsbad, California]], Solomon played two recordings of a [[Santana (band)|Santana]] track; one he had recorded himself and the pre-recorded cassette release from [[Columbia Records]]. He used this technique to demonstrate what he called "the tunnel effect" in the audio range of pre-recorded cassettes and commented to the reporter Sam Sutherland, who wrote a news article printed in ''Billboard'' magazine:

<blockquote>
"The buyer who is aware of sound quality is making his own." "They won't be satisfied with the 'tunnel effect' of prerecorded tape. And home tape deck users don't use prerecorded tapes at all." Yet, contended Solomon, while Tower's own stores show strong blank tape sales gains, its prerecorded sales have increased by only 2% to 3%. With an estimated 15% of the chain's total tape business now generated by the sales of blanks, "it would appear our added tape sales are going to TDK, Maxell and Sony, not you." he concluded. - ''[[Billboard (magazine)|Billboard]]'', Vol. 93, No. 38, 26 September 1981.<ref name=BILLBOARDSS1>{{cite magazine|magazine=[[Billboard (magazine)|Billboard]]|title=Better Cassette Quality Urged|date=26 Sep 1981|volume=93|issue=38|pages=3, 6|url=https://books.google.com/books?id=vSQEAAAAMBAJ&q=pre+recorded+cassette+quality+v+home+recording&pg=PT5|access-date=4 June 2013|first=Sam |last= Sutherland}}</ref>
</blockquote>