Marantz HD77 speaker box cardboard package

HD77 is a model name of

Marantz Marantz is a company that develops and sells high-end audio products. The company was founded in New York, but is now based in Japan. The first Marantz audio product was designed and built by Saul Marantz in his home in Kew Gardens, New York. ...

4-way high-fidelity

loudspeakers A loudspeaker (commonly referred to as a speaker or speaker driver) is an Acoustical engineering#Electroacoustics, electroacoustic transducer that converts an electrical audio signal into a corresponding sound. A ''speaker system'', also often ...

which were produced during the mid-1970s. They were

bass reflex A bass reflex system (also known as a ported, vented box or reflex port) is a type of loudspeaker enclosure that uses a port (hole) or vent cut into the cabinet and a section of tubing or pipe affixed to the port. This port enables the sound fro ...

speakers, but came with a

cylindrical A cylinder (from ) has traditionally been a three-dimensional solid, one of the most basic of curvilinear geometric shapes. In elementary geometry, it is considered a prism with a circle as its base. A cylinder may also be defined as an infini ...

piece of

foam Foams are materials formed by trapping pockets of gas in a liquid or solid. A bath sponge and the head on a glass of beer are examples of foams. In most foams, the volume of gas is large, with thin films of liquid or solid separating the reg ...

which fit into the

bass-reflex A bass reflex system (also known as a ported, vented box or reflex port) is a type of loudspeaker enclosure that uses a port (hole) or vent cut into the cabinet and a section of tubing or pipe affixed to the port. This port enables the sound fro ...

port A port is a maritime facility comprising one or more wharves or loading areas, where ships load and discharge cargo and passengers. Although usually situated on a sea coast or estuary, ports can also be found far inland, such as Ham ...

of the

enclosure Enclosure or Inclosure is a term, used in English landownership, that refers to the appropriation of "waste" or " common land" enclosing it and by doing so depriving commoners of their rights of access and privilege. Agreements to enclose land ...

if the listener preferred the more accurate

bass Bass or Basses may refer to: Fish * Bass (fish), various saltwater and freshwater species Music * Bass (sound), describing low-frequency sound or one of several instruments in the bass range: ** Bass (instrument), including: ** Acoustic bass gui ...

response provided by

airtight A hermetic seal is any type of sealing that makes a given object airtight (preventing the passage of air, oxygen, or other gases). The term originally applied to airtight glass containers, but as technology advanced it applied to a larger categor ...

speaker boxes. However, they were not fully airtight this way, but rather what is known as

aperiodic A periodic function is a function that repeats its values at regular intervals. For example, the trigonometric functions, which repeat at intervals of 2\pi radians, are periodic functions. Periodic functions are used throughout science to desc ...

. They were designed by former JBL Engineer Edmond May. The foam plug in port was in fact a "closed-cell" type which did in fact seal cabinet completely. How it worked was it was cut slightly larger than opening and when inserted, you turned the retainer screw and it would tighten and compress the plug, thereby sealing the cabinet to make the loudspeaker a "suspension" type. The controls on baffle are resistive potentiometers, which changed the response curve of corresponding driver from soft to bright, giving great versatility to adapt within almost any listening environment.

Technical details

Weight: 49 lb (21 kg) Power handling: 250 watts RMS, 330 Watts peak Impedance: 8 ohms

Physical dimensions

Marantz HD77s had a total

volume Volume is a measure of occupied three-dimensional space. It is often quantified numerically using SI derived units (such as the cubic metre and litre) or by various imperial or US customary units (such as the gallon, quart, cubic inch). The de ...

of each. The

cabinet Cabinet or The Cabinet may refer to: Furniture * Cabinetry, a box-shaped piece of furniture with doors and/or drawers * Display cabinet, a piece of furniture with one or more transparent glass sheets or transparent polycarbonate sheets * Filing ...

dimensions In physics and mathematics, the dimension of a mathematical space (or object) is informally defined as the minimum number of coordinates needed to specify any point within it. Thus, a line has a dimension of one (1D) because only one coordina ...

are: Depth: 12 inches Width: 15 inches Height: 28.5 inches

Drivers

The four drivers of the Marantz HD77s are a

woofer A woofer or bass speaker is a technical term for a loudspeaker driver designed to produce low frequency sounds, typically from 50 Hz up to 1000 Hz. The name is from the onomatopoeic English word for a dog's bark, " woof" (in contrast to th ...

mid-range In statistics, the mid-range or mid-extreme is a measure of central tendency of a sample defined as the arithmetic mean of the maximum and minimum values of the data set: :M=\frac. The mid-range is closely related to the range, a measure of ...

tweeter A tweeter or treble speaker is a special type of loudspeaker (usually dome, inverse dome or horn-type) that is designed to produce high audio frequencies, typically deliver high frequencies up to 100 kHz. The name is derived from the high ...

and

super tweeter A super tweeter is a speaker driver intended to produce ultra high frequencies in a multi-driver loudspeaker system. Its purpose is to recreate a more realistic sound field, often characterized as "airy-ness". Super tweeters are sometimes found in ...

. The given

frequency response In signal processing and electronics, the frequency response of a system is the quantitative measure of the magnitude and phase of the output as a function of input frequency. The frequency response is widely used in the design and analysis of sy ...

s are what the crossover circuit feed to each speaker, not what each speaker would respond to with no crossover circuit(full spectrum). The mid-range, tweeter and super tweeter have crossover controls for switching between a laboratory "flat" +/- 0db neutral response and a "room EQ" response. Tested frequency response is measured in an anechoic chamber from 20 Hz to 20 kHz, and displayed in a graph shown in original Marantz brochure. Crossover and frequency response are two different things. Crossover points are established for each driver and their specified frequency range. Without crossover points, the drivers would distort and likely overheat and burn out due to the production of the full spectrum of frequencies, with exception of the woofer which inherently struggles with producing higher frequencies. The drivers together create a complete spectrum frequency response.

Woofer

The woofer is in

diameter In geometry, a diameter of a circle is any straight line segment that passes through the center of the circle and whose endpoints lie on the circle. It can also be defined as the longest chord of the circle. Both definitions are also valid for ...

with a frequency response of 30 to 500

hertz The hertz (symbol: Hz) is the unit of frequency in the International System of Units (SI), equivalent to one event (or cycle) per second. The hertz is an SI derived unit whose expression in terms of SI base units is s−1, meaning that on ...

Mid-range

The mid-range is 4.5 inches in diameter with a frequency response of 500 hertz to 3

kilohertz The hertz (symbol: Hz) is the unit of frequency in the International System of Units (SI), equivalent to one event (or cycle) per second. The hertz is an SI derived unit whose expression in terms of SI base units is s−1, meaning that one h ...

Tweeter

The tweeter is a {{convert, 2, in, cm, adj=on LPF film dome-type. The tweeter's frequency response is from 3 kHz to 8 kHz.

Super tweeter

The

is a 1-inch LPF film dome with response from 8 to 23 kHz, which extends 3 kHz above the nominal range of

audio frequencies An audio frequency or audible frequency (AF) is a periodic vibration whose frequency is audible to the average human. The SI unit of frequency is the hertz (Hz). It is the property of sound that most determines pitch. The generally accepted ...

which can be heard by the human ear.

References

Classic Audio. ''Marantz HD770''
Loudspeakers