Advantages
of the
IDS Technology

Exclusive Distributor

Haig Audio
KenHaig@IDS25.com


From the FAQ's Page
if
you click on a target below it will take you directly to the answer related to that topic.

Single wide range line source

High power handling

Ten dB of acoustic gain

More uniform sound

Eliminates floor and ceiling reflections

Distributed low frequency radiation

Less attenuation with distance

Superior
Imaging
Depth
Spaciousness


Startling coherence

Response stays the same at any listening height

Wide dispersion

Lower harmonic and  
IM distortion


Excellent transient response

Latest driver technology

Magnetic shielding

Small footprint

All the things you DON’T
get with the IDS-25

No image distortion
No subwoofer needed
No bi-amping or tri-amping
No bi-wiring or
tri-wiring
No right and left hand versions
No woofers, mid-ranges, tweeters or crossovers

 

 

 

IDS-25 Frequently Asked Questions

Answers directly from the Designer and Originator
Roger Russell

1. What do the letters IDS stand for?

2. Why does the IDS-25 have better imaging, depth and spaciousness ?

3. What is image distortion?

4. Is the IDS-25 a dipole radiator?

5. Does the system have a “sweet spot” where you must sit for good sound?

6. How does the IDS-25 column avoid room reflections and resonances?

7. Why must the column be so tall and will a short column work just as well?

8. The system is too tall for my living room ceiling height, what do I do?

9. Can I use these speakers in a smaller room?

10 Why is an equalizer required?

11. Why doesn’t the equalizer have different frequency controls?

12. Why does the equalizer have a mode IN-OUT switch?

13. Doesn’t the extra power demand from the bass boost hurt the small drivers?

14. How can such little cones provide any bass, even with the equalizer?

15. What is so unique about these drivers?

16. What is the power handling for the system?

17. Does the system have protection from excessive power?

18. Is there a problem with IM distortion when covering a wide frequency range?

19. What about Doppler distortion when the drivers handle lows and highs?

20 What about comb-filter effects caused by the driver spacing?

21. Why is the sensitivity of the IDS-25 system higher than one of the drivers?

22. How good is the transient response of the system?

23. What are the advantages of eliminating crossover networks?

24. How low does the impedance get?

25. What would it be like to hear the IDS-25?

26. What are the dimensions, how much floor space does the system require?

27. What is single, wide range, line source?

28. What is coherence?

 

 

 

 

 

 

1. What do the letters IDS stand for?

They describe the outstanding features of the system: imaging, depth and spaciousness. The goal was to create a system that would faithfully reveal these listening.

 Imaging is the ability of a speaker to accurately reproduce stereo information so that the listener is able to locate instruments as they were positioned in the actual performance or as they were mixed.

Depth is the illusion that the instruments are located at various distances behind the plane formed by the two speakers.

Spaciousness is the illusion of size, either natural or artificial, giving the impression of a very large room or enclosure having reflections with various amplitudes, time delays or frequency shifts. The synthesized spaciousness used today in popular and electronic music is extremely appealing.

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2. Why does the IDS-25 have better imaging, depth and spaciousness than other systems?

ALL of the frequencies are radiated from the same wide-range drivers that are all in the same vertical line. There is no image distortion. This offers greater accuracy over multiple columns.

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3. What is image distortion?

An example of image distortion is when the fundamental tone of a violin is in one place but the harmonics of that note are in other places. The location and sound of the complete instrument is indistinct. However, if all of the sound from the violin comes from the same point in space, the sound is more realistic. When all the instruments are playing it enables you to experience their total sound, at their individual locations without getting all muddied up with each other. This is true whether you are listening to the softest or loudest passages. The superior imaging of the IDS-25 lets you audibly locate the entire characteristic sound of each instrument more accurately in space and the details are incredibly realistic. The images remain stable, in your listening environment, regardless of frequency or your position in that environment.

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4. Is the IDS-25 a dipole radiator?

No. Some designs depend on drivers that face in different directions or have radiation from the rear as well as the front. This approach uses the room environment to provide multiple reflections that are supposed to be like what happens in a concert hall. However, in the real world, the reflections and absorption of the listening environment control this “room sound” and each listening room is different. This is hardly the way to convey what is in the recording by adding extra room sound to the concert hall sound already in the recording. In addition, a dipole speaker must be placed out in the room. The IDS-25 was designed to be used within a few inches of the wall. The IDS 25 preserves the recording and minimizes the room sound. It does this using only a single column that radiates only from the front and distributes all frequencies throughout the height of the room.

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5. Does the system have a “sweet spot” where you must sit for good sound?

No. In the vertical dimension, the sound will always appear to come from an area centered at the region of your listening height. For many systems, the sound changes when you are standing and then sit down. When you try this with the IDS-25, the sound, whether it is stereo or monophonic, does not change at any listening height.

In the horizontal dimension, stereo sound can seem to come from almost anywhere but the speakers. Sounds can be located in a wide horizontal area. Even if you are listening way over to one side, you can still hear excellent stereo, depth and spaciousness.

When listening to monophonic material, the sound image will appear to be exactly in the center between the speakers at all frequencies. However, a monophonic image will follow you as you move from left to right and if you are directly in front of one speaker, the sound will appear to come only from that speaker and not the other one.

No matter how the recordings are made, the sound images will be revealed with razor sharp accuracy when heard with a pair of the IDS-25 Stereo Loudspeaker Systems.

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6. How does the IDS-25 column avoid room reflections?

The IDS-25 column is very directional vertically but it extends essentially from floor to ceiling. It means that floor and ceiling reflections over most of the frequency range that would normally interfere with the direct radiation are effectively eliminated. At the same time, the horizontal dispersion provided by the small drivers in the IDS-25 ensures a wide radiation angle over most of the frequency range. This is a significant advantage over normal systems that not only radiate sound as much vertically as horizontally but also exhibit response changes with listening height. As a result, the IDS-25 is able to fill the room with sound much more uniformly and at the same time maintain better stereo listening further into your listening room.

In addition, low frequency room resonances are greatly reduced. This is because the lows are being radiated all along the height of each column, exciting room resonances at low amplitude. In comparison a subwoofer or subwoofers located on the floor may build up fewer resonances but at much higher amplitude.

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7. Why must the column be so tall? Will a short column work just as well?

A column of half the height has much less power handling and also has reduced acoustic gain, making the efficiency of a short system much lower. These two factors work against each other by requiring more power but having less power handling ability. You lose the design benefits of the IDS-25 design. In addition, the short column will exhibit vertical directionality and the sound will be different for a standing versus a sitting position, requiring more power for the same listening level.

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8. The system is too tall for my living room ceiling height. What do I do?

The IDS-25 is a custom made system. The cabinets can be made one or two drivers shorter with no serious loss in performance. This will allow the user to fit them in their home and still enjoy all the benefits of the IDS design.

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9. Can I use these speakers in a smaller room?

The IDS-25 is ideal for use even in smaller rooms. Close listening is not a problem because each driver covers the entire frequency range and the sound level changes relatively little as you get closer. You can walk right up to the column and not be aware of any increase in loudness.

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10. Why is an equalizer required?

The response of the drivers is unusually smooth and extended. However, they do not cover the entire frequency range uniformly. The system by itself cannot deliver deep bass. However, by boosting the bass using the equalizer, bass can be extended to below 25 Hz. In the same way, the equalizer can extend the highs to 20 kHz and compensate for losses when the drivers are arranged in a column. The equalizer is carefully tailored to exactly complement the drivers in the column arrangement.

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11. Why doesn’t the equalizer have different frequency controls?

The equalizer is part of the speaker system design and is not intended to duplicate the function of the tone controls that are in your preamplifier. Tone controls are best suited to supplement the tonal balance of program material.

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12. Why does the equalizer have a mode IN-OUT switch?

This switch provides a bypass for the equalizer and response is flat in the OUT position. It means that you can leave the equalizer connected between the preamplifier and power amplifier when you temporarily use a speaker other than the IDS-25. The switch must be at the IN position when playing the IDS-25.

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13. Doesn’t the extra power demand from the bass boost hurt the small drivers?

At first glance, your impression would be exactly right. However, when all the drivers are used in a long column, there is a 10 dB acoustic gain over much of the frequency range compared to a single driver, making the resulting efficiency of the column much higher. Only one tenth of the power is needed for the same listening level.

In addition, there are 25 drivers, each of which will handle at least 10 watts. The entire column will handle 250 watts and still not exceed the single driver power handling.

The heat dissipation capability at high power is outstanding with 25 voice coils per channel. A single coil used in one large woofer is not able to dissipate heat as effectively in comparison.

Also, since the system will handle such high power over the entire frequency range, it means that the mid and high frequency peaks can be handled effortlessly, far better than a system having a single mid-range and tweeter.

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14. How can such little cones provide any bass, even with the equalizer?

It is true that these 3-1/2” drivers are very small compared to the 12” or 15” woofers that you are used to seeing in a system having good bass capability. You might think of the IDS-25 as a woofer made of 25 individual diaphragms all working together. Each one has an effective cone area of only 5.7 square inches. However, when combined together, the effective cone area of 142.5 square inches is equal to that of a sixteen-inch woofer and they couple to the surrounding air very nicely. The equalizer then provides the means to achieve a smooth and extended response for the deepest bass.

The large effective cone area of the IDS-25 not only delivers excellent bass but also effortless sound through the rest of the audio range and fills the room from top to bottom.

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15. What is so unique about these drivers?

This excellent driver has a copper shorting cylinder around the pole piece. Unlike some shorting ring designs, the ring extends through the entire height of the gap and beyond. This is known to reduce distortion, particularly in the voice range, by a factor of 10 or more. The ring also greatly reduces any impedance rise at the higher frequencies that would otherwise reduce high frequency output.

In addition, the cone is made of a woven fiberglass material. This type of textile construction has been used in various dome midranges and tweeters for many years and has proven to furnish smoother response and without the peaks sometimes found in rigid materials such as those having metal cone or dome construction.

What's more, the entire magnet assembly is shielded. The magnet structure is not only reverse polarized but also has an external steel cover as well. It reduces stray magnetic fields that could affect the picture of a television set or other devices if placed in close proximity.

Use of a flat spider, which is the major centering device for the voice coil, assures the same linear cone travel in each direction while keeping the coil exactly centered in the magnetic gap. A thin rubber surround eliminates the possibility of deterioration often found with foam surrounds. The square basket allows closer spacing between the drivers.

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16. What is the power handling for the system?

The maximum peak power for the IDS-25 is rated at 200 watts. However, because of the higher efficiency over much of the frequency range, most of the time, you will need no more than 2 watts.

However, at the lowest frequencies, the bass boost from the equalizer increases power to the column in order to maintain a constant low frequency output. As the frequency goes lower, the power to the column gradually increases. At the lowest frequency of 20 Hz, the power requirement can be up to 100 times greater. It is very rare in music that frequencies this low will require this much power. A power amplifier of 200 or even 250 watts is more than adequate for the loudest of listening levels at the lowest frequencies.

At high frequencies, a boost from the equalizer also increases power to the column to accomplish a constant output. As the frequency goes higher, the power to the column gradually increases. At the highest frequency of 20 kHz, the power requirement can be 10 times greater. This is not a problem for the IDS-25.

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17. Does the system have protection from excessive power?

Yes. The IDS-25 will easily handle short-term power peaks found in music. It is protected against long term, high power levels but there is no guarantee that this circuitry will protect against all types of program material. Care must be taken when the sound becomes distorted at excessive levels, particularly at the lowest bass frequencies. Turn the volume down and wait for ten seconds and then play the system at a lower level for that particular passage. This will allow time for the automatic protection circuit to reset.

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18. Isn’t there a problem with intermodulation distortion for a driver covering such a wide frequency range?

No. The IDS-25 has exceptionally low distortion. When an ordinary driver is used to cover the entire frequency range, you can expect the harmonic and intermodulation distortion to be relatively high. However, the IDS-25 drivers have the same low distortion construction used in design of soft dome mids and tweeters. The cone is actually made of woven fiberglass and dissipates energy over its entire surface, reducing edge reflections and drastically lowering distortion. In addition, the magnet assembly employs the latest technology consisting of a copper cylinder through the entire length of the voice coil gap. This shorting cylinder is known to significantly reduce distortion contributed by the magnet structure to one tenth of conventional driver distortion. This improvement is particularly noticeable in the voice range. The diameter of the cone is small compared to the voice coil diameter and also contributes to lower distortion.

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19. What about Doppler distortion when the drivers handle lows as well as highs?

Doppler distortion occurs when the cone motion at low frequencies shifts the higher frequencies up and down at the low frequency rate. The longer the low frequency cone excursion, the more distortion is generated. If a single driver is used, distortion would probably be audible at high levels. However, the IDS-25 is unusual because the diaphragm motion of the combined 25 drivers at low frequencies is extremely small and modulation distortion is far below audibility.

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20. What about comb filter effects caused by the driver spacing?

The closer the drivers are, the less perceptible any variation in sound is. A spacing of one foot between drivers is obviously too large and if you put your ear six inches from such a column and move up and down, you will be able to clearly hear individual sources, even far back into the room. However, the closely-spaced drivers used in the IDS-25 perform far better. With music, you can come as close as one foot and the sound still appears to be continuous.

 

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21. Why is the sensitivity of the IDS-25 system higher than only one of the drivers.

There are two reasons for greater effective sensitivity compared to a conventional system. First, there is an inherent 10 dB increase in acoustic gain from this long array over most of the frequency range. Second, the sound is radiated in a cylindrical pattern from floor to ceiling. The sound level decreases at only 3 dB for each doubling of listening distance.

In a conventional system, such as one having a single woofer, mid and tweeter, the sound is radiated in a spherical pattern in each frequency range. The sound level decreases 6 dB for each doubling of listening distance.

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22. How good is the transient response of the system?

The transient response of the system is excellent. Good transients or “fast speakers” depend on a driver with a wide bandwidth and low moving mass. The drivers are inherently wide bandwidth. The weight of the moving parts of each IDS driver is very light, measuring only 2.5 grams or 0.088 ounces compared to 45 grams or more for a 12-inch woofer.

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23. What are the advantages of eliminating crossover networks?

Needless to say, the elimination of crossover networks takes away many of the compromises involved in juggling components, drivers and crossover frequencies to try to make the best sound using this older technology. Conventional systems, having a woofer, tweeter and perhaps a mid-range as well, require crossovers, either passive or active. Passive crossovers often involve losses and can cause unwanted changes to the system impedance in order to gain an improvement in response. Having no crossover eliminates the debate about which passive components sound the best. Electronic crossovers require extra amplifiers, adding a significant cost to a system.

Either method involves common difficulties. In the area of the crossover frequency, both drivers radiate the same frequencies and may interfere with each other causing uneven response around the system. A different physical location for each driver adds to the problems.

More importantly, and perhaps not so obvious, is that a driver used to cover one part of the frequency range does not have the same construction, tonal characteristics or dispersion characteristics as a driver covering another part of the frequency range. In the area of the crossover frequency, these differences between drivers cause sudden discontinuities in the overall sound balance. It results in a loss of valuable stereo information. By using the same driver to cover the whole frequency range, all of this can be avoided and a continuous coherent spectrum can be presented.

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24. How low does the impedance get?

The impedance is 7.2 ohms or higher throughout the frequency range. The rated impedance is 8-ohms. The impedance of some systems using crossover networks can dip far below the advertised impedance and cause a mismatch to the power amplifier.

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25. What would it be like to hear a system like this?

It is overwhelming. Perhaps your first impression will be the unusually good bass response. When you first see the system, your eyes and past listening experience with small speakers may tell you that this system would definitely need a woofer or two. Common sense may tell you that you can’t possibly get any deep bass from a bunch of 3-inch drivers. But, the bass is not only impressive; it is free from ringing and “boominess” that is found in some systems.

After making an adjustment for what you see versus what you hear, more benefits can be discovered. The response of the IDS-25 is very smooth. It is free from any resonances, peaks or dips. However, this is not enough to explain the instant reaction you get when you first hear the system. The coherence, when an entire orchestra is playing, is simply amazing. You may realize, perhaps for the first time, that the stereo image, depth and spaciousness provided by this system is totally mesmerizing and you are only aware of the performance and what the artist has created. Not only is the sound from the IDS-25 effortless but it also fills the room from top to bottom and appears to play louder than a typical point-source system. When you combine all of these impressions, it goes beyond overwhelming.

Even if you have been able to distinguish a few of these qualities when listening to your existing speakers, the IDS-25 system can do this better because it has inherent design advantages that other systems do not have. You will most likely want to play your entire music collection over again to discover the many details and enjoyable sounds that you did not hear before.

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26. What are the dimensions and how much floor space does the system require?

Many systems, particularly when a subwoofer is needed, take up valuable floor space. The IDS-25 has a footprint for the base that is only 14" wide and 12" deep. The column itself is only 7-1/2" wide (tapering to 5-1/2" in front) and 9-1/4" deep. The height with the base is 88-3/4” and 87-1/4” without the base. Because the IDS-25 is capable of significant output down to 20 Hz, no subwoofer is needed.

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27. What is single, wide range, line source?

        

This is our patented propagation system where all frequencies radiate from a single plane, in other words, in a straight line. By using full range drivers each center of effort, or cone position, is perfectly aligned with all others creating a precise line source for the sound. The uniqueness of this system is by using full range drivers we have no phase shift distortion from placing the center of effort for the larger, bass drivers behind those of mids or of tweeters. It becomes a perfect aligned source for your listening pleasure.

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28. What is coherence?

Coherence is the ability of the speaker to recreate the original sound in a faithful manner without inducing unnatural reflections and distortion which is not found in the original composition.


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