Hemisphere

Frequently Asked Questions

Over the past few years, selling speakers by word-of-mouth, we have answered some questions over and over. Perhaps some of your questions are included below.

What are the Hemisphere's speaker specifications?

The Hemisphere's drivers are Polk Audio's db521 fullrange car speakers. They are wired in such a way as to be compatible with 4-ohm or 8-ohm amplifiers. Each individual driver is rated at 45W of continuous power handling, meaning that each channel of the Six-Channel Hemisphere can handle 45W, while the Monaural Hemisphere can take up to 270W. Full specifications of the drivers can be found on the Polk Audio website, here.

Why hemispheres? Why not complete spheres?

The first generations of these speakers were designed as full spheres (see A Brief History of the Hemispheres). In 2001, we thought there might be an advantage to building a speaker that could sit flat on the floor or flat against a wall. If we wanted a full sphere, we reasoned, we could simply fasten two halves together. Once we began using the Hemispheres, however, we discovered that one cabinet was sufficient to produce the point-source effect. As a result, we have rarely used two to make a full sphere. Of course, the option remains to put two hemispheres together back-to-back, for those who might want to.

Why are there both monaural and six-channel Hemispheres?

Different speakers for different needs. The "point-source emanation" of the standard mono Hemisphere is the result of each driver producing the same sound. An amplified audio signal fed into a monaural Hemisphere will be reproduced identically by each of the six drivers and will enter the listening environment multi-directionally. The Six-Channel design was created to meet the requests of some of our customers, who wanted each driver to be able to produce a separate signal. And now we offer additional flexibility in an adapter cable that allows your Six-Channel Hemisphere to behave like a Monaural one, accepting a single amplifier signal.

What amplifiers work best with the hemipsheres?

This is not a product endorsement, but rather just a list of amplifiers we have tried with success. We began working with amplifiers by Crown, and now are using Rane amps -- both work very reliably. There are also the portable amplifiers by Stewart Audio, which are a little sensitive, but great and light for luggable performance systems. Finally, we recommend the amplifiers from AcousticImg. Most amplifiers (including home stereo amplifiers) should work well with the Hemispheres.

Do you have any suggestions for cases?

Enduro cases provide a reasonable casing option. The Princeton Laptop Orchestra uses the Enduro 20 x 8 case (Humes and Berg #499 case (12 x 20), with foam). It is a bit on the big side, in both dimensions, but they will cut it smaller if you want. They might also have a smaller diameter version that will work.

Are there any subwoofers that work well with the Hemispheres?

Many people have had good results using Sunfire subwoofers. The "Super Junior" sub is especially portable. We are currently excited about a less expensive, more portable option called the Substage 100 by Sound Matters

What can you tell me about how the speakers are built?

Master furniture maker Ken Malz personally handcrafts every piece of the cabinet from special MDF board, fastens it together, and uses a durable, textured powdercoat finish to cover and protect the speaker. Fiberglass resonance-dampening material is inserted into the cabinet. A Neutrik locking 1/4" jack is wired to the drivers, and all of the components are screwed into the cabinet, hand-tightened to ensure a secure, "buzzless" fit.

These things would look great in my living room! How will they sound with my stereo system?

Virtually all music you might play through your stereo system has been designed to sound best through "normal" front-firing speakers. So, while these speakers might sound interesting (and will certainly look fabulous!), they will sound different from what you are used to. Some of our friends use them in their home stereo systems with complete satisfaction, so let your own ear be the judge.

Where can I read more about the Hemispheres?

If A Brief History of the Hemispheres doesn't go deep enough, you might want to try one of the following links:

• The paper Alternative Voices for Electronic Sound by Dan Trueman, Curtis Bahn, and Perry Cook, presented at the 2000 International Computer Music Conference, gives a more detailed chronology of the speakers' development and the rationale for their use.
• SensInstallation, a presentation given by Curtis Bahn and Stephan Moore at the SEAMUS 2002 conference, contains good photo documentation of the first hemispherical speakers, and some information on the first experiments with a 16-channel grid of speakers.
• The development of a specific spherical-speaker-based instrument is detailed in Dan Trueman's writings about his Bowed Sensor-Speaker Array (BoSSA).
• Learn more about the N-Body project that started it all here.
• Get information about purchasing a Hemisphere or a Six-channel Hemisphere from Electrotap.