Bolzano Villetri™
For Owners
Product FAQs
Customer Feedback
Warranty Registration
Glossary
Home Theater Handbook
INIZIANO I BOLZANO VILLETRI DAYS
For Owners
Home Theater Handbook

Loudspeakers

Part 2


See also: all questions, part 1, part 3

What are the types of materials used for the manufacture of tweeter diaphragms?

Tweeters reproduce high frequencies. Tweeters have low weight diaphragms and powerful magnets, such as high-density neodymium magnets, that allow for extremely accurate and fast diaphragm movements. There are many materials used for the manufacture of the tweeter diaphragms. Aluminum diaphragms are particularly well suited for this task. They are rigid and low mass and reproduce fast tran­sients with high speed, accurate and distortion free sound. Excellent diaphragms are made of Nomex and silk.

What are some highly regarded types of tweeters?

Below is a list of some highly regarded types of tweeters and their characteristics:

  • Aluminum Tweeter
  • 1" inch low mass fast aluminum dome
  • High density large shielded magnet
  • High sensitivity and low resonance frequency
  • Extremely detailed high frequencies Free Air Tweeter
  • Position on Top of the Box for wide dispersion without diffraction, accurate stereo imaging and precise focus

What determines the quality of a speaker's cabin?

  • 1" inch fast Nomex dome
  • High Density Neodymium Magnet Tweeter Double Chamber
  • High quality, high power, high sensitivity
  • Double chamber behind the magnet lowers the tweeter resonance by 1 octave. The resonance is moved lower than the tweeter frequency range. The sound is natural and distortion free.
  • Ventilated voice coil

What kind of diaphragms do middle and low frequency speakers require?

Compared to tweeters, middle and low frequencies require larger size diaphragms, capable of moving the required volume of air to generate the appropriate sound waves.

Why are Kevlar and Alucone speakers an industry favorite for middle frequencies?

Mid-Range speakers with Kevlar®Cones are an industry favorite due to their natural midrange response. Another excellent choice for middle frequency speakers are Alucone® speakers with rigid low-mass Aluminum Sandwich alloy Cone for fast transients, accurate and distortion free sound.

What kind of woofers are good choices for two-way speakers?

For two-way speakers, excellent choices are the Kevlar® Woofers with Kevlar® Cone for natural bass & midrange response. For three-way speakers the Kevlar® Mid-Range is also highly recommended.

What are the characteristics of high quality subwoofers?

Subwoofers must have heavy-duty construction, very powerful magnets and large diaphragms. Some characteristics of a high quality subwoofer is a strong motor system with powerful magnets, high level & low distortion output, and a voice coil especially designed not to require complicated crossover correction. Excellent choices for the diaphragm materials of subwoofers are Carbon Fiber Cones and Polypropylene cones.

What are the benefits of using Diecast Baskets in speakers?

Diecast Baskets are a necessity for perfect mechanical and magnetic behavior due to their strength and rigidity, which is far better than plastic and steel competitors.

Why is a cabinet used in loudspeakers?

When the cone of a loudspeaker moves forward to impart pressure on the air layers in front of it, then an equal and opposite directed vacuum is created behind the cone. The low frequencies generated in front of the cone are non direc­tional and move to cover the area in front and behind the cone. This causes their cancellation since they interfere destructively with the equal yet out of phase low frequencies generated behind the cone.

The ideal way to avoid this phenomenon is to place the speaker in the middle of a large surface. This is known as an infinite baffle. Of course this solution is totally impractical so we therefore resort to surrounding the speaker by a cabi­net. Cabinets are therefore used to support the speaker drives and nullify unwanted cancellations.

What are the ideal characteristics of a loudspeaker's cabinet?

The cabinet design contributes greatly to the response of the loudspeaker and either mimics the free loudspeaker behav­ior (infinite diaphragm design) or uses the enclosed air to improve performance (bass reflex and acoustic suspension design). The ideal speaker cabinet is rigid, so that it does not vibrate by the internal air pressure variations. In addition it must have a large damping behavior to minimize unwanted sound radiation by the cabinet. The cabinet must also have a very high resonance frequency, above the audible range, so as to avoid coloration of the sound.

What determines the quality of a loudspeaker's cabinet?

Most good quality speakers are made of MDF, which exhibits very good rigidity and damping behavior and is easy to use. Other materials commonly used are natural wood, polycarbonate and synthetic materials.

The quality of the cabinet is influenced by factors other than the material of construction, such as the shape and thickness of the baffle and the quality of the welds. In general manufacturers always aim to increase the rigidity and the damping factor of the cabins they use.

What are the advantages of using Narrow Cabinets?

Narrow Cabinets produce sound without diffraction, wide stereo imaging and precise focus. Prism-Shaped Narrow Cabins are the ideal speaker cabins since they eliminate internal standing waves, reduce diffraction and improve the focus of the stereo image.

Why do we need speaker enclosures?

Speaker cabinets, or enclosures, play a key role in the operation of a loudspeaker. As you have probably noticed some loudspeakers have a hole in the cabinet, while others are sealed. Other loudspeakers have no cabinet at all! In general electrodynamic loudspeakers require cabinets, unless they are in wall models. The enclosure is required for bass generation; the reasons where explained in the previous section. There are other types of loudspeakers that do not need an enclosure, such as magnetostatic and electrostatic speakers. We will discuss these in the sections that follow.

What are the basic types of loudspeaker enclosures?

As it was explained previously, an infinite baffle is completely impractical so a loudspeaker designer has to resort to one of the basic types of enclosures: acoustic suspension, passive radiator, ported or horn loaded.

What is the role of the enclosed air in an acoustic suspension enclosure?

Acoustic suspension enclosures are air tight, since they use the enclosed air to dampen the behavior of the woofer, When the woofer moves forward there is a vacuum created behind the woofer that sucks the woofer back to its resting position. When the woofer moves backward there is internal air pressure increase which pushes the woofer to its resting place. A properly designed acoustic suspension loudspeaker has tight and deep bass with a gradual roll off below its cut off frequency. However acoustic suspension loudspeakers tend to be inefficient since the acoustic energy generated by the back side of the woofer is not used.

How does the passive radiator behave?

Passive radiator enclosures are designed to use the energy that is otherwise wasted by an acoustic suspension loudspeaker. A passive woofer which does not have a voice coil and is not connected to the amplifier with any wires, is attached to the enclosure. The passive radiator has an appropriate resonance so it does not move in the upper bass frequencies, so that the enclosure behaves like an acoustic suspension. In lower frequencies close to the passive radiator's resonance frequency the internal air pressure moves the passive radiator supplementing the active woofer and providing some bass extension. The draw back is that bass roll off below the cutoff frequency is very steep.

How does a ported enclosure behave?

A ported enclosure is another way to use the energy that is wasted by an acoustic suspension loudspeaker. By opening an appropriate size hole in the enclosure and attaching a pipe of specific length to it, the low frequencies generated in the enclosure come out in phase with the bass generated by the front of the woofer. Varying the size of the hole and the length of the pipe varies the low frequency extension. The draw back to ported enclosures is bass which may be less tight. Just like the case of passive radiators, the bass response below the cutoff frequency rolls off very steeply

What are the advantages of horn loaded speakers?

Horn loaded enclosures are used to manufacture very sensitive loudspeakers. A funnel is placed in front of the speaker which is inside the cabin, acting as an acoustic amplifier, thus improving the efficiency, the sensitivity and the directivity of the speaker and resulting in very high levels of sound.

Where are horn speakers primarily used?

A properly designed' horn loaded loud­speaker has very low distortion and impressive dynamic area. However designing a proper horn loaded speaker is very difficult. As a result most such loudspeakers are very efficient but have mediocre sound. Horn speakers are therefore primarily used for live concert and PA systems, especially wherever we want to cover large spaces with high audio levels.

What is the task of the subwoofer?

Bass production places great strain on speakers. Speaker manufacturers therefore resorted to the production of an independent unit called, a subwoofer, whose task is exclusively to reproduce the lowest octave of the audi­ble frequencies (20 to 120 Hz). Thus the main speakers are released from this heavy load and as a result they behave more linearly, are more efficient and less expensive. Since low frequencies are largely non-directional, one subwoofer is usually enough to cover our needs.




Bolzano Villetri  |  Products  |  Build your own system  |  Technologies  |  Dealers  |  For owners  |  Home Theater Handbook  |  Links  
© 1995 - 2008 Bolzano Villetri™, Inc. All rights reserved