* Full range preferably
* Time alignment/phase accuracy if forced to use multiple drivers
* high efficiency 92 to 95dB/w/m
Now, because of the nature of the MIDI systems, I added:
* small size
* high end performance at reasonable price
* Clean bass response that could be boosted by the tone controls on the amp
* Good looking to take care of the WAF (wife acceptance factor...)
Generally speaking, I always been an advocate of "form follows function"
and I was determined to build the best speaker in the smallest package possible, using best practice for ALL components involved.
I started by choosing the bass/midrange driver and was attracted early to a 4inch driver made by Audax (I found much later that it was originally designed by Jacques Mahul, then technical manager - before he started Focal/JMLab...).
What I liked about it was that its chassis was made of alloy, very open at the back, and squrish in design, so you could use the smallest cabinet with the maximum size membrane.
As standard, it didn't match my objective of efficiency (probably only 89db/w/m)
but it was quite good over a very extended range (10 Khz) and its frequency of resonance was quite low for such a small driver (61Hz).
See original datasheet here.
So, I organised a meeting with the technical manager of the time (who took over from Mahul) Philippe Lesage, now owner and designer at PHL Audio (www.phlaudio.com).
Philippe was not exactly thrilled by the idea to start with, as this product was designed by somedody else, was intended for high-end TV sets and in Philippe's view, not worthy of a hi-fi speaker.
Besides, I had no name in the industry at that stage.
But to his credit, he listened and the more I got into the brief of my project, and what I was trying to achieve with this driver, the more he became enthused and ready to help.
You have to realise that I was not promising a huge commercial success. I was happy to stay "boutique" as we would say today, so Philippe had to fight internal bureaucracy to get permission to build a few samples for me.
It took a few iterations, but we both knew our trade and finally I had what would be the final item.
We had changed the magnet for a stronger one, reinforce the voice coil to a 9mm long 2 layer on a Kapton former, and in the process gain 4db more efficiency without compromising the midrange or the Fs too much. We also got rid of the dust cap and replace it by a phase plug.
Again, because we wanted the cabinet to stay as small as possible, we chose a TW51 tweeter from Audax (they were making 10,000 of them a day at the time...)
and although it is not the best tweeter on the planet, we managed to get it to work to the best of its ability thanks to a good filter and an impedance compensation network.