Half Duplex See --> duplex

Hard Disk Recorder See --> HDR

HCC = Homogenised Crystal Copper
A type of processed copper wire used in expensive interconnects and other cables. Homogenisation is a form of heat treatment and can be thought of as a refined form of annealing, in this case the copper is soaked for a number of hours at temperatures close to the upper annealing range of the metal to introduce re-crystallisation in order to reduce coring (chemical or metallurgical segregation), and then the copper is cooled down slowly to get a more uniform crystalline structure. This process can be applied prior to extrusion or done to a finished product although the latter is more technically complex it apparently produces better results.

As far as we know Japanese companies are the only producers on the planet to be using this technology in very high quality copper wires and they do the processing in noble gas atmospheres to reduce oxidation, in most other countries this technique is only really used on alloys, although the raw wire made by these companies obviously shows up in cables and interconnects from third parties located all over the world. This manufacturing technique is primarily intended to increase durability of the cables in extreme weather conditions, any sound improvements are purely a by-product of the more coherent structure of the material, homogenisation also makes the cables have a lower tensile strength and hardness.

HDAM = Hyper Dynamic Amplifier Module
A trademark used by Marantz for their discrete buffer amplifiers. Not a novelty in high end audio products but in the mid 90’s the company introduced a standard buffer amplifier screened with a copper shield into their mid-range of hi-fi products and by the 00’s the technology had become a feature in even the budget range of products from the company much like Onkyo started to use a discrete output stage in all of their amplifiers regardless of cost and is as such a welcome development. A discrete buffer amplifier as an alternative to one based on an op-amp IC has less self-noise than the chip version but is more susceptible to electrical and radio interference which necessitates the use of a copper screen.

HDCD = High Definition Compatible Digital
Better known by its initials, HDCD is a simple but ingenious technique whereby a digital signal of 20 bit's or higher is slightly compressed and dithered into a 16bit 44KHz signal (the standard used in common CD's), then "hints" gained from original signal are buried in the least significant bit of the audio stream and on playback extracted by a digital filter that uses them to expand the data, all this resulting in a slight improvement of bandwidth and a not inconsiderable improvement in dynamics.

The technique is not limited to CD standard bit rates but is most useful there since it allows for backwards compatibility, from the viewpoint of any device that can play a standard CD or comparable media a HDCD encoded CD is indistinguishable from a normal one, while units that have a HDCD compatible filter will take advantage of the extra information.

The HDCD technology does however not offer any improvements when the output signal has a resolution higher than 24 bits. Note that the introduction to the HDCD technology on the company's homepage is a bit misleading and also that the original name was High Definition Compact Disk and you may have seen it defined and used as such but Philips lawyers where not happy about the usage of their CD trademark it was soon changed to the current one.

The technology behind HDCD was developed by Pacific Microsonics but the company was taken over by Microsoft and the technology integrated into the Windows Media Player backend. Consumer and Hifi CD players featuring HDCD filters are still available but pro-audio products and mastering equipment is no longer sold or supported so media support has already dwindled considerably.

HDR = Hard Disk Recorder
A device that records digitally and stores the resulting data onto a hard disk rather than onto removable media, or a piece of hardware and/or software that allows a generic personal computer or workstation to become such a recorder.

HDTV = High Definition TeleVision
A television system with higher resolution than the common terrestrial standard. This is not a new term, it has actually been used since the 30's.

1930's (UK) : used to denote the 405 line system that the BBC started broadcasting in 1936, earlier UK designed systems where mostly based on various interpretations of the Baird system and had resolutions as low as 30 lines although the 250 line variant was the most common.

1950's (UK) : Used to describe the 625 and 525 systems that where proposed to replace the 405 line standard, initially the UK was meant to use the 525 system but in the end and adapted the RCA 625 and the PAL system in 1964.

1980's (Japan) : Used to describe the HiVision system introduced in Japan in the latter half of the 80's.

1990's : A standard initially formulated in the USA and commonly referred to as just HD, intended as an answer to the Japanese HiVision format but ran into technical and political difficulties before finally being standardised in 1997 and then only after technical input of European companies and LG Electronics, was quick to gain a foothold in the USA since quality of even the lower HD resolutions offer considerable improvement over NTSC, however it failed to see any significant take-up in Europe until 2010 when the football world cup was shown in full HD in most of Europe, the reason was simply that the difference between the lower resolutions of HD and PAL is less than was anticipated so most broadcasters concentrated on introducing DVB and waited until full resolution HD televisions had become cheaper to introduce the system.

Head Amplifier
An amplifier that brings the I/O of a transducer to a common standard. While it may be confusing why a tape head amp always includes corrective EQ while a moving coil pickup head amp never has any such this has a really simple explanation, it's the standard they are amplifying to that dictates it. A pickup head amp is amplifying a signal to that of an common MM input of a amplifier that is already specified to have a corrective EQ onboard, while the tape head amp is bringing a signal to a line, pro or microphone level standards and all of them expect a straight signal and thus the preamp needs to perform any necessary alterations to the transducer signal before going any further.

The term "head amp" comes from electric record cutters, but you had to buy an amplifier to suit the transducer which was called a cutter head and since the transducers of tape recorders were called heads as well the name stuck for all transducer amplifiers.

Next Page : Jargon Dictionary - Hi to H9 -- Previous Page : Jargon Dictionary - E to G