R/E/P > Mastering Dynamics

So I did not build my own speakers

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I didn't want to highjack the other thread (http://repforums.prosoundweb.com/index.php/topic,1088.0.html) so started this one - the following information relates to these speakers - I found it an interesting read - thought you all might as well

--- Quote --- Hello Dom...Thanks a lot for appreciating the monitors...They are the result of a very long and winding road of experimentation...with quite a few dollars of R&D thrown in along the way by various people.

The drive units are the result of over a year of iterative development in collaboration with SEAS Norway.  As a starting point, I arranged to have samples of every drive unit they make sent to me in all sizes, from their Prestige range all the way through to their high end Excel range. I went through them all looking for any units which I felt had something special going on. I wasn't limiting myself to a preconceived idea about what type of system I wanted to build...I was just exploring assorted drivers for tone, fidelity, smoothness and musicality, with the basic premise that sometimes, for various reasons, and particular woofer or tweeter just hits a "sweet-spot" of parameters.

I finally settled on an 8" woofer from their Excel range, and a 1" tweeter from same as being "special", and decided to develop a 2-way system to keep it "simple".

But, I have a tendency to always "look for more" and...so...ah...I then used these drivers as a starting point, and spent a further year investigating, with the cooperation of SEAS, variants of these units in which I experimented with suspension compliance and surround materials, voice-coil materials and winding topologies, cone coatings, and other modifications to these drive units which I performed here in Australia. The idea was to both improve the subjective tone of the two drivers even further individually, and to bring the relative voltage sensitivities of the tweeter and woofer into perfect electro-acoustic balance at the crossover point so that no resistive padding would later be necessary in the passive network. This was an exhaustive and time consuming process with the end result being a museum of rejected drivers.

In parallel with this work on the drivers, I was also experimenting with the use of steel as an enclosure material due to its high density of 8000 kg/m3. Those M8 monitors at Bertrand's place are not physically large, but they weigh about 53kg. They are 100% welded stainless steel...the front baffle has equivalent mass such that you would need to use 130mm thick MDF to match it...

The crossover network is an ultra-minimalist design consisting of two coils and a single capacitor per side. The coils are wound from Hepta-litz wire. The capacitors are true film and foil. And as mentioned, there are no resistors in the network - this objective was achieved. The internal wire is Van den Hul silver-plated compression extruded high purity copper with Teflon insulation. The terminal points which the crossover parts are soldered to are cut from 3mm thick solid sterling silver wire which I mounted on 4 inch thick Jarrah crossover boards. These sit external to the enclosures. The connection terminals on the monitors themselves are WBT NextGen series.

The tweeter is mounted in an anti-diffraction waveguide of my own design which is CNC machined from a solid block of aluminium. The rear of the tweeter motor is open and therefore the tweeter radiates as a dipole. The pole-piece of the tweeter motor has been CNC machined out to the largest feasible venting hole and no ferro-fluid is used in the motor (as opposed to the ancestor units on which the tweeter is based). It uses a Kapton former instead of aluminium, a high DCR coil, and a small suspension surround instead of large for very fast settling time. The QMS of the tweeter is very high, and although this results in "non-flat" behaviour when the tweeter is run without any filter, it is compensated for in the network and the ultimate result I think you'll agree is pretty special...The low-level detail retrieval is at ribbon-driver level, but with a circular radiation pattern which ribbons never achieve.   

Obviously the system is not perfect...I am never happy and there are always more experiments to be done. It does not cover the lowest octave from 20Hz to 40Hz...this was impossible to achieve simultaneously with other objectives I had for the system...perhaps motive for a future project though...

Best regards,
Perth, Western Australia.

--- End quote ---

So thats the technical details, how do they actually sound? I am always a shade suspcious
with speakers that do not look conventional. Not to say it cannot be good but I like tried and trusted.


That's quite a project, Dom. If Hassan is using steel, presumably there's internal damping so the enclosure doesn't ring?

I imagine the denser the cabinet material the better. I remember reading about concrete enclosures years ago, and Googling reveals that it continues to this day, both manufactured...


...and DIY

http://theartofsound.net/forum/showthread.php?p=74110 (scroll up)

the stereo image on them was amazing and the bottom end fantastic.  i listened for about an hour..mostly to acoustic jazz/funk type stuff.  the vocals hovered in front of you and you could almost reach out and touch the singer.  I didn't get a really good listen to lots of genres but good first impression.  the studio had emes in there previously. 


--- Quote --- although there is some strategic back-wave absorption, there is no damping
of the steel...and this is intentional. However, there is a bracing topology I use
which causes the sidewalls to acoustically phase-cancel at their fundamental
resonance. Above that resonance, I want the harmonics undamped...

--- End quote ---


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