The Coleridge Design aCUBE BMR speaker system
The Coleridge Design aCUBE BMR speaker system
This project fuses the good looks of clear acrylic 6 inch cubes with the exquisite sound of Dr Graham Bank’s BMR speaker drivers.
This project fuses the good looks of clear acrylic 6 inch cubes with the exquisite sound of Dr Graham Bank’s BMR speaker drivers. Read more
About this project
Firstly, a huge thanks for giving me the opportunity to introduce myself and my company, Coleridge Design Associates based in San Jose, California - the heart of Silicon Valley. I’m a scientist by training with a passion for music, however, what I do most of the time and do best is use my skills in physical science engineering to design, make and sell products. My passion for music is what brings me here.
The aCUBE BMR Speaker
Clear sound. Through and through. The aCube is a brand new Kickstarter project that brings you the first ever crystal clear BMR sound system.
- Exquisite sound - best in class BMR loudspeaker technology
- Crystal clear aesthetics - light refracting cast acrylic enclosures
- Convenience - multiple audio inputs and portable option
- Affordability - low cost meets high quality sound
(NEW February 8, 2013)
Bongiovi Acoustics DPS now standard on aCUBE BMR Speaker System
Bongiovi Acoustics DPS will be built into the aCUBE electronics audio amplifier system as standard without the necessity for an iOS app or iTunes plug-in. This will fix the 'bass' distortion at high listening levels that Steve Guttenberg said needed fixing. Bongiovi Acoustics DPS uses digital signal processing to dynamically monitor and correct the bass level to ensure that the aCUBE BMR loudspeaker drivers never go into uncontrolled heavy bass distortion.
CNET's audio guru Steve Guttenberg says: "Fit and finish are superb, and the thick, anodized aluminum speaker grilles look great; the quality of the parts is excellent. The sound is, pardon my pun, remarkably transparent, so good recordings sound absolutely vivid and clear. ...acoustic jazz CDs sound pure and very present, and the stereo soundstage is broad and spacious"
Coleridge Design is on a mission to create a new sound reproduction and loudspeaker brand that leverages design, science and technology to give music lovers awesome sound performance whilst being convenient and affordable. This project is the first step in that mission.
Scott Wilson, MNML, Tik-Tok and Kickstarter
I was hugely impressed with what Scott achieved with Tik-Tok, so much so that I offered to license him a touch-pen technology that Coleridge Design invented and applied for patents. This became the “Lunatik Touch Pen”, Scott’s second successful Kickstarter project which he launched and funded about a year ago. His effort and success inspired me to embark on this project.
The Coleridge Design project – 6.5inch aCUBE BMR Speaker System
I spent some 10 years in audio technology sales and licensing at flat panel speaker company NXT plc, UK. In about 2004, Dr Graham Bank, a colleague at NXT, made a breakthrough in loudspeaker technology inventing the BMR (Balance Mode Radiator) loudspeaker. The BMR is a full range loudspeaker driver which provides outstanding performance. My personal view is that this is the most significant advance in loudspeaker technology since 1925 when Rice & Kellogg invented the loudspeaker as we know it today.
BMR technology has appeared in many standalone loudspeaker products. However, these have largely been in either expensive Hi-Fi or in performance compromised speaker systems. The advantages of BMR speaker technology are multiple, but primarily relate to its pinpoint accuracy yet wide dispersion and extended frequency range. Together this allows the design realization of a high-performance single drive system such as the aCUBE.
This project takes the 4.5in BMR full range loudspeaker drivers from CSS, a company owned by my former NXT colleagues, Dr Graham Bank and Jon Vizor, and marries these drivers with beautiful handmade clear cast acrylic 6.5inch cube enclosures and the latest Class-D amplifier technology from Maxim Integrated. The result: Best in class performance speakers optimized as nearfield active loudspeakers that are stylish, exceptional quality, affordable and convenient.
Find out more about the benefits of BMR here:
Functional aCUBE BMR Demos
Why this project?
Is Stereo on the way out? I saw this news piece by Steve Guttenberg on CNET.com and that headline really threw me. This argument is posed because in order to get a good stereo sound image the speaker separation must be about the same as the listening distance. This in effect renders most mobile devices, docking stations and boom-boxes as single speaker mono devices. With the advances in technology and science at our disposal today I think this may be an unacceptable compromise on performance at the expense of convenience.
You might well ask- if you must have stereo, then why not use headphones? My answer is that although headphones are convenient and have an excellent frequency response over the whole audio band, they are deficient in some respects and awesome stereo speakers are still required for the best user experience.
There is a deficiency in the headphone user experience because listening with headphones without some form of spatial virtualization or virtual speaker modeling the sound is in the center of your head versus on a plane in front of you with speakers. And even with adequate virtualization, movement your head causes that plane, the sound stage, to artificially move with your head.
The greats of music past and present have given us many superb stereo recordings over the last 60 years. Therefore I have made it a personal mission to try and make a difference and ensure that music lovers can enjoy these recordings via access to awesome loudspeaker systems that are not only affordable/convenient but also beautiful
Cost-performance used to be everything but the mobile age has made convenience the game changer. In my opinion, convenience is the primary driving force of today’s consumer electronics products, particularly mobile communication devices. As a designer I believe that convenience/affordability should not compromise design or aesthetics.
Aesthetics – How do we make the speakers beautiful?
By using handmade enclosures in precision-machined and bonded clear cast acrylic. Why use this material? Products made of clear acrylic naturally blend into any décor or physical environment and capture and refract light beautifully. More importantly the material has an inherent acoustic benefit, offering great sound quality. The reason for this is that acrylic has very high internal damping, therefore the enclosures do not resonate and radiate sound as much as other materials e.g. most plastics, wood and aluminum. This means the acrylic speaker enclosures can be made light and free of internal bracing and damping materials ensuring the sound is crystal clear. It is literally a case of form following function.
Another distinctive design feature is the natural anodized 2mm aluminum speaker grills, fashioned after the 1941 Willy’s Jeep grill with 9 slats. The aluminum grills are user customizable and in time we will offer a range of color options. The aCUBE and matching passive BMR cube speaker will ship with the grills fitted, but a kit, comprising shorter screws and a 2.5mm hex socket driver, will be provided to remove the grills and expose the BMR speaker front, providing another customizable element.
We have also crafted beautiful matching speaker stands in clear cast acrylic sheet. The Z shape of the stands help absorb energy from the speakers and prevent sound and vibration being transmitted to the floor or desk/table top; again form following function. Soft polyurethane sound absorption feet or bump-ons are used on both the speakers and the stands to further augment sound and vibration absorption.
Performance – How do we make the speakers sound awesome?
- Dr Graham Bank’s BMR 4.5in speaker drivers - the BMR85DD-N4
- 6in internal cube acrylic enclosures ported and tuned for unbelievable bass
- Maxim Integrated MAX98400A highly efficient class D amplifiers
- Large headroom low noise analog linear preamplifier system
- 60 Watt (12V 5A) switch mode AC Adaptor for intermittent heavy power transients
Cost – How do we make these speakers affordable?
Undoubtedly there are occasions where a single high quality mono speaker works well for the user. What they need is a convenient and affordable option to convert that single speaker system to true full stereo. That’s what we’ve done.
The aCUBE is an entry level BMR speaker with a planned RRP of $180 which works perfectly and to an exceptional standard as a single speaker. To convert to stereo, just add the matching passive CUBE BMR speaker with a planned RRP of $120.
How have we kept costs down? The aCUBE enclosure is CNC machined from 6mm cast acrylic sheet and assembled by hand, so tooling and NRE (non-recurring engineering) costs are minimized. The minimum order quantity to achieve best pricing is less than 500 pieces meaning it is scalable to any quantity. As quantities and sales increase we can also contemplate multi-colored transparent acrylic enclosures.
Also, we’ve kept the electronics simple without compromising on quality by using ubiquitous 3.5mm stereo jack inputs. There are two inputs - 1CH which mixes stereo into mono for single speaker use and 2CH which is used for normal stereo . This technique avoids the use of switches thus increasing system reliability. Additionally, digital inputs for Apple Airplay, Bluetooth, Optical S/PDIF and USB 2.0 Audio are available as individual optional add-on adaptors which plug into the 3.5mm jack inputs allowing the user to tailor the system to their particular application.
Convenience – How do we make these speakers convenient?
Optional adaptors mean that all forms of digital audio source e.g. TV, iPhone/iPad are compatible. Wireless adaptors (Bluetooth and Apple Airplay) enable the speakers to be used with mobile devices such as the iPhone/iPad and Android smart phones/tablets. The Airplay option is particularly convenient when using iTunes for music and video on PCs and Macs.
Using the aCUBE to replace low-quality TV speakers is a great application, particularly for TVs used with set-top boxes or DVD/Blu-Ray players. Optical S/PDIF gives the best results but wired RCA can also be used with readily available 3.5mm to RCA adaptors. (S/PDIF is the Sony-Philips Digital Interconnect Format, an interface which provides a low noise connection using optic fibers between CD, BlueRay, DVD players and speaker systems.)
For PCs, Optical S/PDIF is best for low noise, but the wired 3.5mm jack is standard. The USB 2.0 Audio adaptor is also an option for PCs that do not have S/PDIF.
An auto-off feature on the aCUBE amplifier system means that when there is no audio input for 1-2 minutes the system goes into sleep mode waking instantly when audio appears. This is perfect for Bluetooth and Airplay streaming, as well as TV speakers.
There is a volume level control on the aCUBE back panel but this is really ‘set once and leave alone’. The volume level will generally be controlled by the source device, be it smart phone, tablet, mac, PC or TV. Even then we use a high quality conductive plastic potentiometer for the volume level to ensure low noise and longevity. This scheme also makes a dedicated aCUBE remote control redundant.
Portable Option: A Convenient Supercapacitor + Battery Pack and Road Case Option
The design uses an efficient Maxim Integrated MAX98400A class-D amplifier ICs meaning that the system can even be run on primary batteries. However we see this being an exceptional/emergency scenario when mains power is just not available.
In order to provide an estimated 30 to 40 hours continuous use we have designed and built a 12V/15V Battery Pack operating from a set of 10 AA Alkaline primary or fully charged 2000mA to 2500mA rechargeable NiMH batteries.. Normally, AA batteries, configured in series as they are here to deliver 15V or 12V (primary or rechargeable respectively), particularly when partially discharged, are very poor at delivering the intermittent heavy power transients required for high quality audio. To counteract this we've supplemented the battery pack with a bank of internal supercapacitors.
Supercapacitors have drawn much attention in recent years due to their high power density, reversibility, and long cycle life. They are found in a wide range of applications from smart phones to electric vehicles and the rapid price reduction in recent years has made them affordable in applications like this.
We’ve included a battery low indicator and battery test switch as well as protection circuitry in the form of input and output resettable polyfuses and transient voltage suppressors to protect the battery pack from misuse.
We have added a high-power USB charging port designed to be used when no mains power is available. The USB charging port will automatically switch to charge just about any mobile device out there. This has been achieved by incorporating an auto-detect feature that monitors USB data line voltage, and automatically provides the correct electrical signatures on the data lines to DCP charge compliant devices up to 2.3Amps (Typ).
Here on Kickstarter we are offering a limited number of a Road Case aCUBE BMR stereo systems with Bluetooth adaptor and supercapacitor battery pack in a custom designed lightweight aluminum road case. This system will come in really handy in remote locations and when the lights go out!
Not only acrylic speakers, but also acrylic Z-Stands
The Z-Stand for the aCUBE speakers is 10in tall, the Z shape helps absorb energy from the speakers preventing sound and vibration being transmitted to the desk or table top. The Z-stands are another example in this project of form following function. Soft polyurethane sound absorption feet or bump-ons are used on both the speakers and the stands to further enhance sound and vibration absorption.
Thank you again. We hope you come along with us on this exciting journey. And tell your friends! Geoff Boyd Founder & Managing Director Coleridge Design Associates, San Jose, CA. December 28, 2012
aCUBE Specifications (Stereo System)
- Drivers: 2 x BMR85DD, 4½ inch BMR
- Driver impedance: 4Ω nominal
- Driver inductance: 75µH
- Driver Power handling: (IEC268-5) 20 W
- Enclosure volume: 3.5 liters
- Enclosure type: Tuned reflex port
- Frequency response (TBC): 50 Hz - 20 kHz ±5db on axis
- Amplifier: MAX 98400A (20W + 20W)
- Power supply: in 100V – 240V AC, out 12V, 5A DC
- DC Input: 2.5mm DC Jack 12V nominal (16V max )
- Inputs: 3.5mm jack. 1CH L+R mixed mono. 2CH L, R Stereo
- Input Sensitivity: 0dB, 200mV RMS, 4.7KΩ
- Volume level: +15dB MAX
- Auto-off sensitivity: < 5mV RMS after 1- 1.5 mins
- Audio leads: 3.5mm - 3.5mm stereo, 3ft3" (1m)
- Speaker leads: Speaker cable extension, 16AWG, 4ft
- Enclosure Material: 6mm clear cast acrylic
- Dimensions: 6.5in x 6.5in x 6.5in
- Weight: aCUBE: 3.1lbs, passive CUBE 2.8lbs
Optional Add-on Adaptors Specifications
- Airplay: Apple Airport Express - Simultaneous dual-band 802.11n Wi-Fi
- Bluetooth: Logitech Wireless Speaker Adapter for Bluetooth® audio devices
- USB 2.0 Audio: Coleridge Design based on XMOS XS1-L1 USB HS Audio 2.0 in custom natural anodized aluminum extrusion enclosure
- Optical S/PDIF: Coleridge Design based on Wolfson WM8804/WM8524 96Kbs/24bit stereo DAC in custom natural anodized aluminum extrusion enclosure
Optional Supercapacitor Battery Pack + USB Charger Specifications
- Batteries: 10 x AA batteries Alkaline or rechargeable NiMH (Nickel Metal Hydride). Batteries not supplied
- Supercapacitors: 6 x 5F (3V) electrochemical double layer capacitors (EDLC) with active charge balancing system
- Supercapacitor hold-up time: With batteries removed - approx 2.5mins full power audio playback. (Also useful when changing batteries)
- Universal USB Charger port: Auto detect on USB data lines to provide to DCP charge compliant devices up to 2.3Amps (Typ)
- Controller: Battery test switch, low battery indicator, input and output polyfuse current limit protection
- Enclosure: Custom black anodized aluminum extrusion enclosure
- Output: 15V nominal for 10x Primary Alkaline AA batteries; 12V nominal for 10x NiMH rechargeable AA batteries
Risks and challenges
Risk Analysis for the Coleridge Design aCUBE BMR Speaker project
All product components have been tooled and manufactured to pre-production and Coleridge Design is confident that there will be no design or manufacturing issues in scaling these products through to any level of production. Contract manufacturers have been selected and are fully engaged with firm quotations and have all produced prototypes and pre-production samples. These samples have been built, qualified and tested in house and sent out to professionals and consumers for review and feedback with excellent results. The products are now fully ready for production and scale up.
There is a minimum order quantity of 500pcs for the BMR85DD-4N speaker driver component at the heart of this project. The maximum lead-time for this component is 60 days. If Coleridge Design can guarantee an initial business level of about 350pcs of the BMR85DD-4N in aCUBE single and two speaker systems, then it can fully fund the project and have a basis for moving forward to any pledge level and quantity of business. We have set the funding level to $45,000 to meet this goal with an ability to absorb unused speaker driver components. The BMR speaker driver supplier has the ability to meet any volume requirement up to 5000 pcs per month with the same lead-time. And in excess of 5000pcs per month with agreed estimated forecasts and the same lead-time. There are second source suppliers with similar pricing and lead-times.
The acrylic enclosures are manufactured from standard 6mm clear cast acrylic sheet which is in ready supply worldwide. The enclosures will be fabricated in China and shipped to USA for assembly by a contract manufacturer who has familiarity with the project. The acrylic fabricators in China have already built several pre-production units for evaluation. The QA is excellent. Typical lead times for the acrylic enclosures up to 500pcs is 10days and there is no minimum order requirement. More importantly the fabrication process does not require the massive tooling expenditure and other NRE costs typically associated with CE products. The acrylic enclosure fabricator has the ability to meet any requirement that we may have up to 5000pcs per month without adding capacity but with lead-times going from 10 to 30days. And any quantity with 60 day lead-times by adding subcontractors and capacity.
The only additional NRE tooling expenditure required is for extrusion dies and punch tools for the aluminum hardware. In total this NRE cost is a low four figure US$ amount and manageable at the minimum startup level. The requirements for this project are a quite modest amount of aluminum hardware and any quantity envisioned is easily managed by the chosen fabricator or one of several alternative aluminum fabricators worldwide.
The 12V 5A AC adaptor is a common universal input (100-240V AC) switched mode power supply used in LCD Monitors and there are multiple sources with global supply.
The only single sourced electronic component in the design of the aCUBE is the MAX98400A IC. Coleridge Design has a close working relationship with Maxim Integrated, San Jose, CA and their distributor Avnet and we do not see any risk in using this single sourced product. All other electronics components are multi-sourced and readily available ex-stock from distributors.
Other than the S/PDIF & USB 2.0 adaptors, the digital input adaptors are sourced from third parties who do not in general require significant minimum order quantities to meet the delivery and cost requirements. The Coleridge Design S/PDIF is based on a reference design from Wolfson Microelectronics, Edinburgh, Scotland and the components required to make this adaptor are stock items which can be obtained from any Wolfson distributor. Likewise the Coleridge Design USB 2.0 digital input adaptor is based on a reference design from XMOS, Bristol, England for which components are similarly available. These platforms are chosen for audio quality but are non core and can be substituted should the components become unavailable or go out of production.
The CM who will assemble the PCBs and the final product in USA is UL, ISO-9000 certified, headquartered in Santa Clara, CA and has operations in China.
Manufacturing the Coleridge Design aCUBE and passive BMR speaker products falls into three broad capacity levels with reasonably clear visibility for risk and growth to any size business.
Up to 1000 pcs per month; 10,000 pcs per annum – Made in USA
1000 – 10,000 pcs per month; 100,000 pcs per annum – Made in China
More than 25,000pcs per month; 1M+ pcs per annum – Made in USA
Coleridge Design Associates LLC, San Jose CA. December 21, 2012
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