When pro audio meets HiFi

As many of you know, I never discuss about my work in public forums. Being a professional designer owning a speaker factory (I manufacture booth drivers and cabinets), I limit my self in providing some help here on SP when I have some spare time (unfortunately, very few). I'm also very lucky that my business is running extremely well, so I don't need to promote my stuff (anyway, I only do OEM, so I can't talk about the products of my customers). That's why I don't share my work.

However, I have just finished a project that is completely off my standard production, a 3-way speaker intended for home (2.0 exclusively for music). This speaker is a limited edition of 5 pairs, that will not be sold but that I will give away to my best customers as a gift to thank them for their support over all these years. 

So I'm pleased to introduce REF312:

The idea was to design a highly dynamic speaker with Pro Audio DNA but with smooth HiFi sounding character, one that can be listened for long period of time without any fatigue, even at high SPL. The choice of 3-way came immediately to my mind and the tour de force is the very special cone used in the 6.5" mid driver. This handmade in Japan model is loaded with silk fiber and it uses a special pulp from a tree that you can only find in Japan. The surround is made of a complex material, a mix between foam, rubber and adhesives (its not the standard foam that will fall into dust after 2 or 3 years). The goal was to reach a warm but still detailed reproduction. Very difficult balance indeed. But the result was so good that I have decided to use this type of material in a 6.5" mid driver that I use in pro audio cabinets (line array and 3-way speaker). 

The HF is my standard 1.7" polymer dome that I sold more than 10,000 pcs in 2 years. Ultra smooth and with the right capacitor, it offers a very natural reproduction.

The LF is nothing special but it took me lot of revisions to get the sound I wanted. I did not target for deep bass but for a revealing sound that is fast and clear, but still has lot of body.

Finally, the xover is something a bit special. When I designed the drivers, I carefully matched the efficiency of the 3 sections in a way that I don't need to use any resistor in serial in order to reach the highest clarity the drivers can achieve. 

2* custom 12" LF with damped kraft paper cone 

1* custom 6.5" mid with silk fiber loaded Japanese cone

1* 1" exit / 1.7" VC compression driver with Polymer dome on elliptic horn

Xover points: 450 and 2.5kHz (run only in passive mode)

Power handling: 600W RMS (pink noise 8 hours)

Nominal Impedance : 4 ohms

Frequency response: 45~24,000Hz -6dB 2PI (on the floor)

Average efficiency: 96dB/1W/1m

Cabinet tuning freq: 45Hz

Nominal directivity: H75*V50

Cabinet : heavy braced 24mm 17 layers birch plywood

Feet: 22mm thick Aluminum (CNCed)

Finally the frequency response on axis (2PI, 1/12oct smoothing, 0 represents 95dB)

and 20 degrees out of horizontal axis:

Overall, I'm pleased by the result and I hope the owners will be pleased too ! As you can see the frequency response has a boost on LF and HF to make the reproduction very smooth and appealing. I did not target a flat response because it will be driven by a hifi preamp/amp without any EQ.

Next step is the custom amp I'm developing with an electronic engineer to match the sound character of the speakers. I will update the topic in few weeks, when the full Aluminum chassis will come back.

That's all for now, if you have any question, don't hesitate to ask 

Cheers,

Arthur

With front grill it's a bit boring, standard black fabric glued on a wood frame:

Hi Tony,

well, you can't say it better !!! 

This project took me a full year (in my spare time) to accomplish. Even if I did not started from scratch, the final result is soooooo different than a PA speaker and for that I use very different materials. 

To give an idea, 3D CAD and acoustic design of the cabinet was done over a week-end. Mid driver FEMM FEA and mechanical drawing in a week. But fine tuning of sound character, ie subjective sound quality, was a headache and took me months. 

The great thing about this project is that I had to open my mind a lot and I have visited many high-end hifi shops in Guangzhou and Hong Kong to make sure I don't do something stupid for the intended usage. Finally, what I have discovered is that many high-end hifi products sound "beautiful" with lot of details and speed but totally lack dynamic range of pro audio speakers, especially in MF/HF range...

You're right, mid-range can be tricky to adjust if you want to make a "do it all" speaker. However, I've learned through the years that these "do it all" models are finally average everywhere. That's why I believe in the specialized tool for the intended job. Following this principle, voicing adjustment became natural. 

My customer needs a wedge coaxial monitor ? no problem, let's make a forward mid range (one of my trick is to higher the 2kHz range to get this "voice on your face" that singers love)

Now I have to R&D a speaker for high SPL nightclub environment ? I will a do smiley type of EQ that put mids and high-mids backwards.

For REF312, it will be used at home with many kind of music, but I know that the owners will push quite often the SPL to make a private party, so I made mid/high-mids slightly recessed to "feel the bass" and also to get a natural loudness EQ at low volume when they listen to some acoustical stuff for a relax environment...

I will put a REF312 pair at home next week, so I will tell you how I feel it, but one thing is sure, I'm already working in a updated version, with much higher SPL (my original idea was to use 2 15s but my customers wanted a WAF compatible slim design)

Cheers,

Arthur

Tony,

The surround base material comes in sheets that are molded (it's a special kind of rubberized foam), then treated to my specs (by adding adhesives) and finally CNC machined to my size. A picture below for you to have a better look:

Regarding voicing, as I said previously, I don't use any resistor in serial with the drivers. It helps a lot to achieve good clarity. Please find below the xover for this speaker:

each 12" LF is 8 ohm, mid range is 16ohm, and HF is 8ohm

As you see, I don't step back anything. Having the luxury of developing my own drivers (even for 30pcs !!!), I can match the sensitivity of each section to reach whatever result I want. I believe this approach is the one that provides the less compromise.

BTW, if you want to test one of this 6.5", you can contact me in PM, I can arrange samples for you 

Warm regards,

Arthur