Q1. Why are you main loudspeakers “limited range” loudspeakers?
R. There are quite a few reasons. The first one is that there is no inconvenient to do so, but there are some advantages:
- The size of the enclosure is significantly smaller
- The low-mid frequency cone displacements are reduced, which minimizes the distortion
- The acoustic damping is significantly improved
Q2. So, you are using a subwoofer to reproduce frequencies below 100 Hz. But you also recommend another subwoofer in the systems layout. Why?
R. Yes. The first subwoofer is a bass extension loudspeaker. It is only reproducing the low-frequency information from the L,C,R channels.
The other subwoofer(s) is (are) reproducing only the LFE channel.
The reason is that the LFE signal is recorded separately from the L,C,R channels at the production stage. So it is not necessarily in phase coherence with these channels, and mixing them for play-back in a single loudspeaker can produce unwanted phase oddities, and particularly cancellations in the response.
So we prefer to allot different loudspeakers to L,C,R low-frequency content and LFE, and these speakers can be located in different places of the room as well.
Q3. Why are you setting the crossover frequency at 100 Hz instead of 80 Hz like THX ?
R. IN a THX system, there is a 80 Hz crossover frequency only when a bass management is involved, mixing the L,C,R low frequency content with the LFE.
As we don’t recommend this mix, our setups are not involving this bass management at all. So, the THX crossover is not used and there is no compatibility issue.
We prefer to set the crossover frequency at 100 Hz rather than 80 Hz because it has allowed designing the loudspeakers cabinets at about half the size.
Q4. So, what is the signal feeding the subwoofer allotted to the L,C,R low-frequency content?
R. It is the sum of the L,C,R signals with a low-pass filter. The sum and the crossover functions are performed by our DP 48 digital crossover.
Q5. What about the surround low-frequency content?
R. There is very little LF content in the surround signals, and it is not differentiated from the L,C,R as the ear cannot localize frequencies below 100 Hz in a closed room anyway. This signal is already present in the front channels.
So, we consider that there is no need to reproduce it separately. This is practice, not theory. In theory, there could be an individual LF signal in a surround channel. In that case, we would have to add another DP 48 for routing it to the subwoofer. In reality, it never happens as sound engineers know that placing such a signal in one or more rear channel would only create problems in the room where it is played back.
Q6. Why are you using steel plates for the front and rear parts of the enclosures?
R. Because steel has a much higher density than wood or MDF. Using steel, we can reduce the total depth of the loudspeakers enclosures, and this is a most desirable features. All our enclosures, except the Raijuu 2 subwoofer, are only 4” deep or less.
We are not using steel as such, but a sandwich of 2 steel plates with a plastic film between. This damps the steel, avoiding ringing tones.
Q7. You are using a layer of foam covering the front panels of the loudspeakers enclosures. Why?
R. As we are using a decorative frame, and because of the form factor of our enclosures that is needed for the way they are to be installed, we need to avoid edge diffraction. The foam we use is Basotect, a highly sound-absorbent material.
Q8. What are your other design criteria in your systems?
R. The sound; the sound; the sound