Озвучителни тела за китара и бас

разбойник · Март 22, 2005

Напоследък няколко човека ме питат и затова реших да пусна такава тема, така всички ще могат да ползват информацията.

Статия от сайта на Celestion, бях я свалил от там преди няколко години. Полезно четиво за китаристи

Guidelines For Cabinet Design

LEAD GUITAR

Lead guitar speakers are a unique area of speaker design. A loudspeaker is usually a transducer, designed to faithfully reproduce the acoustics of the signal presented to it. An electric guitar speaker however is a creative part of the music, contributing its own character and tonality. The ‘instrument’ an electric guitar player uses is really a combination of Guitar, Amplifier and Speaker. All 3 parts are vitally important to a good sound.

As guitar speakers are different to other speakers, so guitar speaker cabinets are different to hi-fi or PA speaker cabinets. Deep, thunderous bass is not required (the low E of a lead guitar is 82Hz). High frequency reproduction is a positive disadvantage, allowing unpleasant harmonics and electronic noise to be heard. Distortion free sound would be a disaster.

Guitar cabinets consist of two things; guitar speaker drive and a box. The box design is acoustically less critical than that for hi-fi or PA systems, but proper construction is essential. The cabinets should be solidly built to ensure no joint vibration (unpleasant buzzing) and adequate strength to withstand hard use. Remember that guitar speakers are quite heavy and amplifiers which sit on top of guitar cabs are even heavier. Internal bracing is generally not required, but battens inside the joints are good if your woodwork skills do not extend to complex corner joints, and a central bracing post can be advantageous in a 4x12.

Most quality cabs use 15-18mm plywood for the main cabinet, with MDF for the baffle (the part the speaker is mounted to), but they can be constructed of any material. Many budget cabs are made of chipboard (cheap, but poor strength, ruggedness and sound) or MDF (easy to machine, but heavy and dead). Maple, mahogany and walnut are often used for high quality cabinets.

The important characteristics of the cabinet material are strength, sound and ease of use. Lively resonant materials, such as plywood or real woods, vibrate in sympathy with the speaker and enhance the sound, but should be at least 13mm / 0.5" thick, or they will unduly colour the sound. Most woods or wood composites will be strong enough at this thickness. When considering price, you should also consider cabinet finish. Cabinets can be painted or stained, or covered with a vinyl or carpet finish. Real woods finished with a stain can be very exclusive and expensive looking!

Open back or sealed boxes should be used. Open back gives a looser low end with less depth, and 'figure 8' directivity (sound field looks like an 8 when looked down on from above the cab). Sealed boxes give tight, deeper low end but are more directional, giving less spread of sound. Vented / tuned / ported boxes are not recommended for lead guitar, as they can damage guitar speakers. The box size is not critical. The baffle size is more important in open back boxes (larger = more low mid presence), and for closed back boxes larger volume means deeper but looser bass. Do not use internal acoustic wadding, it is inappropriate for guitar cabs, reducing sparkle and life.

Mount the speaker securely using bolts into T-nuts, not self tapping screws. Do not overtighten so the housing rim bends. Ensure the speaker is protected from the front, as the cone is easily damaged. The speaker can be front or rear mounted.

In summary;

• Strong, rigid construction with no buzzes or rattles

• No air leaks if sealed box

• Plywood or real wood construction preferable

• Size not critical

• Ensure speaker is adequately mounted and protected

NB We do not advise mixing different impedances, as this can lead to uneven power sharing between speakers, causing one speaker to be overdriven and damaged, while the other is underdriven. See our loudspeaker connection page for further details.

THIELE SMALL PARAMETERS

Thiele Small parameters are useful for controlling the low frequency response of sealed or ported cabinet systems by changing the cabinet internal volume, and port dimensions. They have no relevance to open back cabinets, and guitar speakers are not recommended for use in ported cabinets (as the increase in cone excursion below the tuning frequency can cause the thin paper edge of the cone to tear), so this only leaves sealed or 'closed back' cabinets. However, electric guitar speakers do not reproduce 'low' frequencies (the low E string of a lead guitar has a fundamental of 82Hz) and so the frequencies at which Thiele Small parameters have significance are mostly below the operating range. Also, the parameters are measured at very small signal levels. Guitar speakers become non linear at very low levels compared to other types of speaker, greatly reducing the significance of Thiele Small parameters in actual speaker use. Using the Thiele Small parameters of a typical guitar speaker, you will find that halving or doubling the cabinet size makes minimal difference to the response. The cabinet size, shape and construction are of far higher significance than the internal volume. Cabinet design using Thiele Small parameters ignores these most fundamental aspects. Important factors include the material you make the cabinet from, the panel sizes and shapes, how they are joined, how the cabinet is finished, the mounting of the speaker, etc. These, not Thiele Small parameters are the critical factors in the design and ultimately the sound of a guitar speaker cabinet.

Това би трябвало да е достатъчно за направата на качествена колона.

Ето тук има още информация за тези, които искат да навлязат повече в материята или да правят нещо по-екзотично. Препоръчвам на субекти :evil: , които смятат да свирят настроени чувствително по-ниско от нормално (т.е. ниско Ре не се брои, да кажем от До надолу). Има и нещичко за басисти:

http://www.duncanamps.com/technical/speaker_cab.html

Това са връзки към две статии за осъществени конкретни проекти. Първата е доста "про", а втората по-аматьорска и традиционна.

http://www.core-sound.com//bottom-article.html

http://www.geocities.com/SunsetStrip/Bistr...91/speaker.html

По-общи статии:

За инструменталните усилватели и колони:

http://sound.westhost.com/instamps.htm

Съвети за озвучаване на бас на живо от Dave King

http://www.kingbass.com/soundtips.html

Ако някой реши да прави нещо - да пита. Ще помагамq доколкото ми стигат опит и познания.