High quality compact speaker system. Encyclopedia of radio electronics and electrical engineering

Encyclopedia of radio electronics and electrical engineering / Speakers

 Comments on the article

The magazine "Radio" has repeatedly raised the issue of the poor sound quality of many acoustic systems (ACs) produced by our industry. For a long period, they remained the weakest link in the sound-reproducing tract. In recent years, speakers of a rather high class have appeared, such as 35AC-021 ("Estonia"), 35AC-012 (S-90). However, they are still produced in insufficient quantities, are expensive and have significant dimensions. The modern consumer, when buying an AU, is also forced to be guided not only by its parameters, but also take into account the possibility of placing it in a residential area. And from this point of view, inexpensive small-sized speakers of medium power in competent acoustic design could be of the greatest interest. Here, by the way, I would like to emphasize that the opinion prevailing among radio amateurs that the more power, the better the speakers, is not entirely true. A much more important parameter that determines the quality of the system is its ability to reproduce without distortion the dynamic range of the signal, which is determined by the sensitivity. Increasing it by 3 dB is equivalent to doubling the speaker power.

Taking into account the above considerations, a high-quality small-sized speaker was designed, the description of which is offered to the attention of readers.

Main Specifications

• Rated (passport) power 15(35) W
• Rated electrical resistance 4 ohm
• Rated frequency range 40...20 Hz
• Frequency response unevenness in the frequency range 50...18 Hz, ±000 dB
• Characteristic sensitivity 86 dB/W/m
• Total characteristic harmonic coefficient at electric power corresponding to the average sound pressure of 94 dB, in the frequency range, Hz; 1000...2000 1,5% 2000...6300 1%
• Dimensions 260X500X265 mm
• Weight 14 kg

Schematic diagram of the inclusion of dynamic heads and AC crossover filters is shown in Fig.1.

Ris.1

This is a three-way system, made in the form of a phase inverter based on the low-frequency (LF) 15GD-17, mid-frequency (MF) 20GD-1 and high-frequency (HF) ZGD-47 heads (their main technical characteristics are given in the table).

1) Scatter for a batch of six heads.

2) Taking into account the resistance of the wire connecting the head to the separation filter.

The volume of the phase inverter (17 l) was chosen based on the technical characteristics of the LF head 15GD-17 and is optimal in terms of obtaining a flat frequency response with a sufficiently high efficiency [1, 2]. The use of a dome head of the closed type 20GD-1, which does not require a protective box, made it possible to save the usable volume of the speaker without increasing its dimensions, and also to obtain a wider radiation pattern than when using a conventional cone midrange head, for example, 15GD-11.

In the described design, two symmetrically located phase inverter tunnels are installed, which made it possible while maintaining their cross-sectional area and tuning frequency unchanged. significantly reduce their length, which is important for small speakers. The filter section frequencies (1000 and 6000 Hz) are chosen from the condition of ensuring the minimum unevenness of the frequency response. A second-order filter with a frequency response slope of 12 dB per octave was used as a low-pass filter, and third-order high-pass filters with a frequency response slope of 18 dB per octave were used as a low-pass filter. The operation of the 20GD-1 dome midrange head with a second-order band-pass filter is not recommended, since it leads to poor matching of its radiation with the radiation of the HF head.

The use of the described crossover filter required the in-phase inclusion of the heads, which provides good phase and frequency characteristics of the speakers.

The AU housing (Fig. 2) is made in the form of a rigid structure, which made it possible to exclude overtones from the secondary radiation of the walls.

Fig.1. Front panel and speaker section:
1 - rear wall; 2 - block of separating filters; 3 - connector SG-3;
4 - sound-absorbing material; 5 - upper wall; 6 - phase inverter tunnel;
7 - protective casing of the HF head; 8 - HF head 3GD-47; 9 - decorative overlay
HF heads; 10 - protective mesh of the HF head; 11 - MF head 20GD-1;
12 - decorative overlay midrange head; 13 - plate for fastening the midrange head;
14 - foam rubber gasket; 15 - LF head 15GD-17; 16 - protective mesh
LF heads; 17 - decorative overlay of the woofer head; 18 - side wall; 19 - front panel.

Drawings of the front panel 19, top and bottom 5, side 18 and rear 1 walls are shown in Fig. 3, 4

Fig.3. Wall drawings

Fig.4. Front panel drawing.

They are made of two sheets of plywood 10 mm thick glued together (PVA). You can get acquainted with the manufacturing technology of AC cases in [3]. The entire inner surface of the case (except for the front panel) is pasted over with sound-absorbing material 4 (felt). Heads 8, 11, 15 are placed on the front panel along the axis of symmetry. All of them are protected by decorative overlays 9, 12, 16 (Fig. 5), and bass and treble heads are also protected by grids 10, 17.

Ris.5

The woofer is fixed on the front panel through a gasket 14 made of porous rubber. The same gasket is placed under its decorative overlay (it is conditionally not shown in Fig. 2). The midrange head is mounted on the panel through a foam pad, which is also conventionally not shown in Fig. 2. Sealing of the HF head is achieved by using casing 7 filled with sound-absorbing material (wool). The bass reflex tunnels 6 are made of ebonite, but cardboard or soft grades of plastic can be used. Connector 3 is installed on the rear wall for connecting speakers to the AF amplifier and board 2 with crossover filters is fixed (see Fig. 6).

Fig.6. Separation filter board.

Filter coils are wound on frames made of insulating material with a diameter of 50 (L1) and 24 mm (L2, L3). Coil L25 contains 12, L80 - 54, and L1 - 132 turns of PEV-2 wire with a diameter of 146, 3 and 68 mm, respectively.

The filters used capacitors K76G1-1 (C1, C2, C3) and MBGO (C4, C5), PEV resistors (PEVR and C5-16 can be used).

Subjective examinations by "pair comparison" of the sound of this speaker and industrial samples 15AC-208, 15AC-109, 25AC-109, 25AC-027 showed some advantages of a home-made system in terms of such parameters as naturalness, purity and transparency of sound. AFC AS. as well as the dependence of the electrical resistance modulus of the loudspeaker ¦Z ¦ on frequency (red curve) are shown in Fig.7.

Fig.7. Frequency response of the speaker and the dependence of its electrical impedance modulus Z on frequency.

It should be noted that the design of the AC box allows, instead of the 3GD-47 HF head, to install the 6GDV-4 head (the old name 6GD-13) in it, which does not require a protective casing and has a wider dynamic range, lower harmonic coefficient and higher efficiency. The variant of its mounting on the front panel of the speaker is shown in Fig. 8, and the frequency response and the dependence of the total electrical resistance modulus ¦Z ¦ on frequency (dashed line) are shown in Fig. 9.

Fig.8. Mounting option for the HF head 6GDV-4.

Ris.9

The design of the described AS was tested at the Moscow Electrotechnical Institute of Communications. The authors express their deep gratitude for this work to the staff of the Department of Radio Broadcasting and Electroacoustics.

Literature

1. Aldoshina I., Voishvillo A. High-quality acoustic systems and emitters. - M .: Radio and communication, 1985.
2. Vinogradova E. Designing loudspeakers with smoothed frequency characteristics. - M .: Energy, 1977.
3. Ephrussi M. Loudspeakers and their application, - M .: Energy, 1976.

Authors: V. Demidov, E. Zemskov, Moscow; Publication: N. Bolshakov, rf.atnn.ru

See other articles Section Speakers.

Read and write useful comments on this article.

<< Back

Latest news of science and technology, new electronics:

Artificial leather for touch emulation 15.04.2024

In a modern technology world where distance is becoming increasingly commonplace, maintaining connection and a sense of closeness is important. Recent developments in artificial skin by German scientists from Saarland University represent a new era in virtual interactions. German researchers from Saarland University have developed ultra-thin films that can transmit the sensation of touch over a distance. This cutting-edge technology provides new opportunities for virtual communication, especially for those who find themselves far from their loved ones. The ultra-thin films developed by the researchers, just 50 micrometers thick, can be integrated into textiles and worn like a second skin. These films act as sensors that recognize tactile signals from mom or dad, and as actuators that transmit these movements to the baby. Parents' touch to the fabric activates sensors that react to pressure and deform the ultra-thin film. This ... >>

Petgugu Global cat litter 15.04.2024

Taking care of pets can often be a challenge, especially when it comes to keeping your home clean. A new interesting solution from the Petgugu Global startup has been presented, which will make life easier for cat owners and help them keep their home perfectly clean and tidy. Startup Petgugu Global has unveiled a unique cat toilet that can automatically flush feces, keeping your home clean and fresh. This innovative device is equipped with various smart sensors that monitor your pet's toilet activity and activate to automatically clean after use. The device connects to the sewer system and ensures efficient waste removal without the need for intervention from the owner. Additionally, the toilet has a large flushable storage capacity, making it ideal for multi-cat households. The Petgugu cat litter bowl is designed for use with water-soluble litters and offers a range of additional ... >>

The attractiveness of caring men 14.04.2024

The stereotype that women prefer "bad boys" has long been widespread. However, recent research conducted by British scientists from Monash University offers a new perspective on this issue. They looked at how women responded to men's emotional responsibility and willingness to help others. The study's findings could change our understanding of what makes men attractive to women. A study conducted by scientists from Monash University leads to new findings about men's attractiveness to women. In the experiment, women were shown photographs of men with brief stories about their behavior in various situations, including their reaction to an encounter with a homeless person. Some of the men ignored the homeless man, while others helped him, such as buying him food. A study found that men who showed empathy and kindness were more attractive to women compared to men who showed empathy and kindness. ... >>

Random news from the Archive Remote speed limit in Tesla vehicles 03.07.2018 Tesla has begun distributing updates to its mobile app and on-board software for electric cars, with the updates reportedly bringing a remote speed limit feature. The new option will become available after downloading the automotive firmware version 2018.24 or higher. On a mobile device, an application with a version of at least 3.4.1 must be used. If these conditions are met, owners of Tesla electric cars will be able to remotely limit the maximum allowable speed and acceleration dynamics using a smartphone application. In particular, the limit can be selected in the range from 80 to 145 km/h. This feature will be useful if the owner of a powerful electric car has handed it over to an inexperienced driver, say, to his child, who has only recently joined the ranks of motorists. In addition, the option can theoretically help in case of car theft: by limiting the speed, the owner will make it easier for the police to pursue the attacker. Note that Tesla cars also have Valet Mode. When it is activated, the maximum speed is limited to 110 km / h, and the power drops to 25%. In addition, the glove box and luggage compartment are locked, access to settings and personal data is blocked. This mode can be activated when the machine needs to be handed over to a third party.

Other interesting news:

▪ Flex ATX 500 W 80 Plus Platinum Power Supply

▪ Monitor ASUS ROG Strix XG43VQ

▪ Processor architecture LoongArch

▪ Improved power generation from dissipated heat

▪ OmniVision Image Sensors for Smartphones

News feed of science and technology, new electronics

Interesting materials of the Free Technical Library:

▪ section of the site Tips for radio amateurs. Selection of articles

▪ article ENT diseases. Lecture notes

▪ article Why do we have two nervous systems? Detailed answer

▪ article Workshop in a city apartment. home workshop

▪ article Converter for fluorescent lamp with controller. Encyclopedia of radio electronics and electrical engineering

▪ article Capillary pump. physical experiment

Leave your comment on this article:

All languages ​​of this page

Arabic	Hebrew	Polish
Bengali	Hindi	Portuguese
Chinese	Italian	Spanish
English	Japanese	Turkish
French	Korean	Ukrainian
German	Malay	Vietnamese

Home page | Library | Articles | Website map | Site Reviews

www.diagram.com.ua
2000-2024