Hi all,
I can understand the industry has achieved a very bad name for itself what with all the bogus claims but here is some science from our end if anyone is actually interested in the facts about the FocalStage design. Yes it does use the new Jordan Eikona driver in 2-array configuration. The comments here are typical of misconceptions concerning the capability of such a design and we thought we would just say our bit to put things straight:
1. The FocalStage does exceed these bass specifications. Paul Messenger measured -3db at 20HZ for his review in Hi-Fi + magazine in his large room. Our specifications are based on accurate modelling and average measurements in room will exceed them. A simple demo with dispel any myths here.
2. The central cap is not a pole cap or dust cap but a phase plug as it is static and does not move.
3. The term ‘Ambient HF unit’ is a descriptive term as it is not deployed as a tweeter in the usual sense of the word. No crossover is deployed, only a high pass filter as its output supplements the full range array at very high frequency (around 9KHz), adding a degree of dispersion. In this manner the dispersion can be fine-tuned to some degree to taste and/or room. We could have just said ‘tweeter’ but it doesn’t hint at this unusual deployment.
4. The bass response of a system is not just affected by the driver size. A large driver certainly helps as it allows a sealed cabinet. Efficiency is proportional to square of driver area at low frequencies. We don’t use a sealed cabinet though, it’s a tuned mass (port) loaded transmission line. The advantages of this is that it will produce a much lower frequency than would be expected from the quarter wavelength length of the line and this is where the confusion may arise. Yes the output exceeds 29 Hz -3db and sensitivity 89 db/w/m. Actually at 30 Hz the cone is hardly moving at normal bass volumes and it has a total excursion capability of 2cm. The system acts like an acoustic lever where the rear of the cone is loaded (with back pressure, slightly out-of-phase) and power passing through the driver is efficiently converted to air movement at the port. So yes it can do quite literally room shaking bass if that is what you really want. It is actually quite impossible to describe bass output and quality without using some subjective terms (facilitator) so all I can say is if someone requires a demo I will be willing to justify this claim. Yes the Jordan drivers do have accurate bass specifications and their parameters are such that they are very effectively used in transmission line alignments, with the result that bass response is much better than you would commonly expect from the visual look (similar looking standard speakers).
5. Transient response of a well-designed transmission line is not too dissimilar to that of a sealed cabinet. Bass reflex is down quite a bit. It is important to damp a transmission line the correct amount and this is what maintains transient response and overall bass quality.
6. Some people say – why don’t you use a dedicated bass driver? Apart from the above explanation and the misconception that you can’t get decent full bass from an array of full-range drivers, what you do get is a coherence (no crossover) and immediacy (light cone with powerful magnet) and low distortion (low excursion at resonance, high linear excursion possible). Also a 3-way is not suited to a transmission line so you are best using a large driver in a sealed cabinet or one with internal partitions. This means a much larger driver and cabinet to what amounts to the same bass response. A dedicated bass driver is less well integrated as it won’t do the mid-range/treble. You end up with the typical multi-way speaker compromise. Some people say a full-range design is a compromise. It’s certainly more dependent on the design (driver and deployment) being a good one but the advantages are numerous if you get it right.
7. OK I have said the positives what are the disadvantages of this approach. The cost – a decent full-range driver is not cheap (2 less so). They won’t do a uniform room-filling sound with little stereo focus. They won’t do ear shattering bass levels regardless of distortion levels that some may like.
Kevin
Acoustic Insight
