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

got pics with the grill on? 

whats the terminal a the back...binding post? 

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

Thanks for the kind words  

In this case, I used Smaart7 with my trusty calibrated Earthworks M30 mic and Motu AudioExpress interface (love the very stable digitally gain controlled preamp).

Other system I daily use is Kirchner ATB801 in production and R&D

Cheers,

Arthur

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

Did you also step the mid back to line the voice up with the Bass as apposed to giving the mid more projection?

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

Hi Tomebomb 

In the first post, I said that the cabinet is 100% made of 17 layers 24mm thick birch plywood. Here's a cut view of it:

For the paint, it's a special formulation for my usage, single component, water borne based (ie washable with water and soap), low VOC, no toxic, no smell, applicable with a roll or a gun machine. I buy it from a US company called Momentive (was Hexion few months ago)

because it looks cool ? 

more seriously, the real reason is to physically match the MF and HF phase at the crossover point. In other words, I recess the mid to be able to align it with the HF. The goal is to have a good clean impulse response and keep a flat frequency response out of axis.

sorry the late reply, was very very busy...

For the round around the mid, first I must say that it makes nearly no difference in sound. If I remember, it's less than 0.5dB in frequency response on a very limited bandwidth. The reason is simple, this horn is too small and the expansion is too fast to get any significant loading.

Regarding the manufacturing, because I only had 10pcs to do, it's fully made by hand. No tool involved. If I had to make a production of this design, I will make custom guide and bit, but it will still be slow with the hand finish to get a nice smooth surface. 

Finally, I got the amp to go with it. After so many months in the bench, tweaking the circuit design, it's nice to see it with a proper casing:

Specs: 

Just to clarify an important thing, the "reference" name must be taken literally, ie it's a reference point for me to judge other amps. No way it must be taken "reference" = the best. In this case, "reference" = a reference point for comparison.

Happy new year 2014 to everybody   

--Arthur

you are not welcome here with your arrogance and your "my stuff is the best, everything else sucks" tone you use in every topic on this forum 

for other people reading this story, I did not use a standard PCB design, my electronic friend engineer did his own, and even if the circuit is very simple and similar to many kits available (basically from a old GOLDMUND Mimesis topology that you can find the schematic everywhere on internet), the difference comes in the parts used. For example, I bought dozen of capacitors to find the tone I like and complementary to REF312. I've tried anything from pure copper foil, pure aluminum foil, silver, even gold from companies like Cicada, Obligato, Clarity cap, Panasonic, Mundorf and Jantzen just to name a few. 

They are 1200V decoupling caps 

BTW, working now on a more powerful version with at least 80V rail to get 400W 8 ohms / 800W 4ohm RMS output power. It will be used to push subs in my Karaoke room. First calculation with 15kg 2200VA transformer and 450x150x400mm chassis (passive cooling) gives a healthy 40kg beast 

Generalhammond wrote: That amp looks beautiful.

Thanks guys, I like the vintage stuff when it comes to design 

of course I can share, this forum is all about that ! 

I bought it from a company called TEKRAM. It's a 2 parts kit, the controller and the VU meters. On Taobao, the Chinese ebay, you can find this stuff here:

http://item.taobao.com/item.htm?id=8631373263" rel="nofollow - http://item.taobao.com/item.htm?id=8631373263

http://item.taobao.com/item.htm?id=8795346517" rel="nofollow - http://item.taobao.com/item.htm?id=8795346517

edit: the company shop on Ali Express:  http://www.aliexpress.com/store/group/VU-Meter/208837_211068331.html" rel="nofollow - http://www.aliexpress.com/store/group/VU-Meter/208837_211068331.html

Cheers,

--Arthur

It's unfortunate that you talk when you don't know all the facts. ! It doesn't make you humble nor sociable. And by the tone of your messages, I don't know what I did to you, but it looks like that you don't like me. No problem, even like that I give you a hug 

Anyway, regarding the speaker, 2 important remarks:

1- the intended users are all working in Pro audio and they wanted to have something at home that can give them good SPL. Only this request put out of sign 99% of HiFi speakers available in the market. 

2- My friend customers value my work much more than anything they can buy at the shop. Because what I do is genuine and because of the friendship we developed all these years working together. And they like it even more when they get something that is owned by 5 persons in the world. Maybe it's a concept you can't understand but that is the truth.

But I don't care, I feel out of concern because I don't sell cheap stuff. In fact, my prices are usually 30% higher than my competition. Not because I make more profit but because I use higher quality parts, I pay 30% more my workers than my competition, I give my workers free life insurance, a flat (one person per flat, not a dormitory with 6~12 people per room), I buy at fair prices from my suppliers and so on.

But more important, I don't play tricky games like selling the same stuff to competitors and my products are 100% original, all designed in house from scratch. 

Now about the value of the gift and about better to give better service ?

Other example, I keep stock of all my parts to guarantee a 10 years trouble free service. 

But the key thing is that the majority of my customers know my price system, including my BOM (Build Of Material) and my exact profit. Thus they are free to check my cost and if they find a part that they can buy cheaper, we discuss about it. It already happened many time.  

So no fear and no point to ask me for a future discount on my price list because of a gift 

 

I'm not sure if I understood your message. So to clarify, who are you calling a "chinese copycat" ? Me ?

For the record, all my speakers are genuine and my customers enjoy tremendous success with it. Some numbers to back it up. I started my own factory 3 years ago:

first year, I produced 2,500 speakers

second year, I produced 4,500 speakers

Third year (2013), I made 9,000 speakers

Right now, I have my production plan full until end of March and I think I will do around 15,000 speakers for 2014. All of this during a very bad global crisis period and with less than 15 customers !!!

In fact, I must be one of the very few factories to refuse new customers, like no late than last December when I closed the door to a very famous Italian Cie because I already have 2 customers in Europe and I promised them to not take any more OEM in this area...

That being said, on the Chinese scale, I'm still a tiny player. I'm very humble about my small success and I still have lot of things to improve on every aspect of my business to become, maybe one day, a significant player in this market...

ok ok ok I stop there, I already said too much. Sorry for the long message folks 

Cheers,

--Arthur

 

and is smp mykey?

 

 

 

Be like old times having rog back on the forum

well it will feel very weird. I know Rog personally, and I hope (believe?) that we share a good respect for each other, even if the last time we met was around 5 years ago when he came to the factory of my previous partner and we spent a full evening listening to some of my speakers. He came with some nice tracks and we shared lot of troughs. Then we went for diner before I sent him back home.

Of course, people can change over time, but for such strong personality, I don't buy it...

as we all know, it doesn't exist a single product that every body likes

colors... shapes... we all have different taste...

--Arthur

Thanks for the clarification 

As I said, if someone in China produces genuine pro audio speakers from his own R&D lab, it's me !

I tried to use the search engine of the forum + google to find who called me "typical Guangzhou" company without success. Do you have the link ?

Cheers,

Arthur

WOW. 

Pot, kettle and black big time!!

SMP,

Now regarding, the tweaking of my small DIY amp project, everything you said is like coming from captain obvious. I clearly stated the topology, I said the circuit was very simple but time was spent on finding the right parts and contrary to what you said, it makes day and night difference. I invite anyone to try an off the shelve LME49810/49830 kit from China with let's say basic 2SA5200/1943 bipolar and standard caps to my own version with highly regarded Hitachi MOSFET and custom caps. The standard kit will sound lifeless/dull in comparison, it will sound more harsh, and will lack the details of my version. One of the reason is that LME49810/49830 can work with both bipolars and MOSFETs but the reproduction differs due to their silicon difference. LME also shows different THD and harmonic distortion numbers when working with bipolar or MOSFETs: Lower THD with bipolars but higher even harmonics, given the harsh reproduction with bipolar.

Warm regards,

--Arthur

ahah so true Mickey 

2 years ago, I was invited by a business relation to meet with one Harman OEM factory who wanted to make their own speaker brand. They asked me to design a product for them, the project was interesting so I made a prototype and few weeks later I came back to them for a listening. In the room, many no name speakers, some JBLs produced by this factory and a bunch of SRX. My small 12" sounded much better than anything they had. The project manager was very embarrassed and after some talk in Chinese with the team came back to me like that: "sorry, your speaker is too good, can you make something that is not better than our customer product ?" 

I told them it was already my entry level and I'm not interested to put my name in garbage 

Since, they moved on something else, an internal solution I think. But few months ago, I saw their products in a shop and asked for a demo. Man, they succeed in their goal of offering lower quality than JBL... and by a good margin  

PS: SMP, please go back to school and learn to read, I did not call you a d*ck, I said you act like a d*ck. BIG difference.

Hi Rish,

How are you ? I will go to SA in May or something, hope we can have a beer  

I'm the first sorry to see how this topic is going but you may have missed it, I was trying to avoid damage in ignoring SMP. But he keeps coming back, flooding this last page... That being said, you are right, better to close this topic.

BTW, to make things clear, I have no issue with Mickey, he's nicely asking questions, I reply, we exchange, that's it. and I know him, he's a good chap 

Others had questions too and it was all fine. I even assisted a fellow to source VU meters 

but this SMP guy, sorry, he ruins every topic with his rude and inappropriate behavior. This morning again here:

http://forum.speakerplans.com/new-leco-amp-modules-650w-8r1200w-4r_topic84281_post835517.html#835517" rel="nofollow - http://forum.speakerplans.com/new-leco-amp-modules-650w-8r1200w-4r_topic84281_post835517.html#835517

Moderators, please close.

--Cheers,

Arthur