After introducing the wildly successful SE 9 amplifier, several customers have written that they would like to see more efficient nOrh loudspeakers. We point out that the Prism 6.6s are quite efficient but they are outside the budget for many of our customers. Several customers have suggested various drivers that they would like to see us use to increase efficiency.

There is a difficult balance that all loudspeaker designers have to play with. These include, size, efficiency, power handling and bass output. Generally speaking, you have to give up something to get something. A speaker that is more efficient will likely produce less bass. The reason is that efficiency is generally obtained by making the cone lighter. Lighter cones will generally produce less bass in a given size cabinet.

One of the drivers that was suggested to me would roll off at 150 Hz. This would absolutely force customers to buy a I also believe that the drivers we have been using simply sound better with more amplifiers that the drivers that had been suggested. There is another way to improve efficiency. That is to use more drivers. This also increases power handling and lower distortion. The drawback is that as you add more drivers, you have to increase the size of the cabinet and the additional drivers increase the cost.

I designed a loudspeaker two years ago that I never released. It used three full range drivers and fit into a corner. The idea was that for home theater, you could put the speakers into the corners of the room. It seemed like a good idea until I started noticing how few room had four corners. The speaker sounded very good but it stayed on the drawing board. I had also designed a center speaker I called the Wedge. It looked like the nOrh 4.1 but was designed to be hung from the ceiling. The speaker had three drivers. One pointed to the center, one to the right and one to the left. The listening tests had been gone very well but it was another project that never saw the light of day.

Linda with Pyramids

The Pyramid viewed from top

As more and more people asked for efficient speakers, I tried to dust off these older designs and see if I could do anything with them. I asked our factory manager to mount three drivers in an 11 meter drum so that we could do some tuning. She sent over two pairs. One pair had three drivers and the other had four drivers. I don't know exactly way but the four driver version sounded much better. I know that four drivers should sound better but I don't know why it was so much better. The improvement was dramatic.

I started thinking about what could we do to put four drivers on these older designs. I thought that I could mount a driver on the back of the Wedge. That wasn't possible because the area wouldn't be enough to handle the two magnets. It then occurred to me that we could do a pyramid. We did some research and found that pyramids were built with a variety of angles from 38 degrees to over 53 degrees. The pyramid designers finally settled on 51 degrees as the right angle for pyramids. During my research, I also came across several articles that spoke about the perfect acoustic nature of pyramids. I even came across an article that talked about a musician who recorded inside a pyramid and a description of how great the recording sounded.

The Pyramid has four full range drivers mounted on all four sides of the speaker. Each side is tuned so that the sound coming from each side is identical. This means that no matter where you sit, you are sitting, you will hear exactly the same thing. If the speaker happens to be to your left, you will hear the same as if you are sitting right in front of the speaker. With a pair of Pyramids, you will enjoy the full fidelity of the music, no matter where you are sitting.

This is dramatically different from how most loudspeakers work. Most loudspeakers are omnidirectional but only for some frequencies. Bass information below 100 Hz is omnidirectional while frequencies above this become more and more directional. A very good generalized way to think of this is that a woofer is like a light bulb while a tweeter is like a spot light. If you walk around a loudspeaker, you will hear the information from the woofer but you will loose the information from the tweeter. This is why most loudspeakers have a very small area where you actually hear the correct stereo image. This is called the sweet spot. Some people will toe in their speakers because they sound better. This is because they are pointing the tweeter where they are seated so that they get all of the information from the tweeter.

With the Pyramid, the listener is free to roam around the room and enjoy the music. Because there are four drivers, the Pyramids are unbelievably sensitive. They are rated at 94dB sensitivity. I have seen other efficient loudspeakers but many of them will handle no more than 15 watts. The Pyramids will easily handle 80 watts. At 80 watts, the Pyramids will produce more than 109 dB!!! The Pyramids will play louder than this but nobody should ever play their music this loud.

• Omnidirectional
• 4 x 3 inch full range drivers
• Sensitivity is 94 dB at 1 meter
• Maximum power handling is 80 watts
• Frequency response: 65 Hz to 22, 000 Hz +/- 3dB
• Dimension: 50cm X 50 cm X 35 cm (WxLxH)
• Weight: 15 Kg

The Pyramid is a classic design

Pan, our factory manager with the Pyramids

Suppose we put the speakers right up against the rear wall. In a 12 foot room, the speakers are only two feet behind the listener. This is not far enough away from the rear speakers to be in their sweet spot. To solve this problem, some people put the speaker to the side. This would work except that the information recorded onto the tracks assumes that the sound is coming from behind the listener and not from the rear.

Recently, some decoders have tackled this problem by adding additional drivers. Dolby EX adds a sixth speaker in the center rear and there are also seven channel arrangements. All of these are trying to come up with a way to get the correct information from the rear channel to the listener.

The Pyramid provides an elegant and inexpensive solution. Because there are four drivers, it doesn't matter if the speakers are only one foot behind the listener. There will always be a full range driver pointed at the listener.