Hello. Welcome to Real Wood Audio.
♦ Designing and building audio speaker systems that touch all your senses. ♦
Real Wood Audio, LLC Philosophy Statement
On a recent trip to my local big box supply store I had the opportunity to walk through a display of one of the latest innovations in home climate control systems – the electric heater. These particular heaters are unique, though. Usually constructed with a PTC (positive temperature coefficient) ceramic or thermostatic heating element, they are designed to look like realistic fireplaces complete with moving flames. Plug it in and flip the switch. Or, in some cases, hit the remote control. A moving backlit Rayon material printed to look like realistic flames comes alive with candelabra light bulbs while a gentle fan blows heat into the room at the rate of 4600 BTU’s/hr. The fireplace is about as effective as a 1400 Watt hairdryer at heating your living space. However, what makes these electric heaters so popular is their realistic appearance. Instead of wasting $20 on a hairdryer, you can have the $200 stand-alone fireplace insert that plugs into your standard electrical outlet. Or, if you don’t have an actual fireplace in which to place an insert – you can purchase a complete mantle and electric fireplace combination to decorate your home for anywhere from $800 to $1700, and more.
Being a professional woodworker, it was the display of mantles that caught my eye. Specifically the woodwork and the finishing that went into making the faux fireplaces appear so real. From a distance I was struck with the quality and detail of workmanship. I could see some Victorian, 1900’s period design in a few of the models. Others represented a more modern southwestern architecture. There was something for every décor with four or five different designs on display in this single area. Each design came in at least two different color or finish combinations. Placards in the display area described the mantle construction as “made from solid wood and real wood veneers”. It was an impressive display to say the least.
Impressive that is until you get up close. (And, this is the part that drives my wife absolutely crazy.) I love to inspect the detail of furniture items offered for sale. I am always hoping to learn something more about woodworking by admiring someone else’s efforts. Unfortunately, I found myself disappointed once again. Like so much of the mass produced furniture found on sale today, the impressive display of mantles were constructed from nothing more than recycled pulp and paper products held together by hazardous glues and resins such as Urea Formaldehyde1 and, of course, a few misguided staples.
Apparently in legal speak “solid wood” can mean anything that is not actually hollow. And, I mean “anything”. In this case “solid wood” means Melamine2 which is a plastic resin, Medium-Density Fiberboard (MDF)3 - softwood materials broken down into fibers and combined with resins, or high-density fiberboard (Fiberboard)4 exploded wood fibers with resins. I believe that “solid wood” is used to describe just about any type of “engineered product” that can readily be used in an automated manufacturing environment due to its overall consistency dimensional stability at the time of manufacture. If “real wood veneers” were present in any of the products I examined they were not detectable by the human eye. What you do see practiced in typical furniture manufacturing is an automated veneer-like process whereas printed sheets of plastic are vacuum formed over the engineered materials then melted and/or glued into position. The visual effect can be one of natural grains and real wood fibers. However, the reality is anything but. It is really just pulp and paper products with a molded texture finish held together with resins then printed with wood-looking plastic. A plastic molding technique constructs the intricate architectural moldings for the mantels. This automated process uses high pressure (measured in tons) to squeeze the engineered materials mentioned above into the various shapes and sizes by using hardened metal cavities that represent the woodworks of old. Once glued or stapled in position and with a finish printed on them, these moldings can look every bit as realistic as the rest of the man-made items used to construct the mantles – from a distance.
I could easily pick up one of the assembled mantles off the floor. So, off hand I am guessing that the entire assembly weighs a little more that a whole 4 x 8 sheet of ½ inch thick MDF. A sheet of ½ MDF goes for about $20 at the same box store. Now add in the finish work, which is accomplished with spray equipment either in booths, or in some countries right in the great outdoors. Then think automation. We’re not going to build just one of these mantles. We’re going to build thousands. The cookie cutter construction process for these pieces of furniture is broken down into micro steps of cutting, milling, drilling, molding, assembling, and finishing. An automated piece of equipment dedicated to each step in the production process. Cut to shape on one machine. Groove milling on another. Several machines all operate in conjunction to create the parts necessary for a complete mantle assembly. It is the production line mentality capable of turning out a finished product at the rate of one every five minutes. Even if you consider materials, overseas labor, amortization of capital equipment, packing, and shipping, the production cost of a mantle would come in under $60 each. You find them on the display floor at retail prices to pay for the distributors and retailers that bring them to you. In fact, you’ll find most commercial furniture constructed this way. This is the world of automation and production engineering I made my career in.
Why would I be carrying on about fireplace mantles found in a big box store? To illustrate the cookie cutter mentality used to create most audio speaker systems found in the market place today. Take a look at what is currently offered by retailers. Most speakers look as if they came from out of space. Futuristic designs that reflect the materials they are constructed from. Unless you reside on the Space Station, there will be some difficulty matching your home’s décor. Unfortunately, you will find the same man-made materials used for the mantel construction above also used to make speaker cabinets. MDF is the preferred because of its dimensional stability. Molded plastics come in a close second. Automation requires a supply of consistent feedstock in order to perform properly. Irregular shapes and thickness do not work well without human interaction. Hence, pre-manufactured materials are used for all the reasons outlined for the cookie cutter automation process above.
There are several writings by various authors concerning the construction techniques of speaker cabinets. Most of these authors are proponents of construction materials such as MDF. The predominant reasoning, aside from ease of construction, is the density of the construction materials as they relate to resonance. Upon closer study, MDF may not be the best choice. Aesthetics aside, let’s examine the density of the various materials commonly used in speaker cabinet construction:
||41 - 52 lb/ft3
|Oak, American Red
|Oak, American White
|Oak, English Brown
|Walnut, American Black
As you can see from the chart above, selection of materials is paramount. When referring to performance, selection of materials is second only to cabinet design. The concern about resonance is understandable given the open box design of most commercial speaker cabinets and kits. MDF is less dense than solid hardwoods. Cabinets designed with large unreinforced wall areas will resonate regardless of material. Therefore, MDF can be seen as a production short cut to make up for the lack of design or economy of construction. The fewer materials that go into a product, the less it costs to produce. Softer materials tend to absorb more vibrations and make these shortcuts less noticeable to the listener. As a paper product, MDF also absorbs moisture and will degrade when wet. And since an MDF finish can only be painted or laminated on, it is susceptible to chips, dents, and breakage under everyday living conditions.
Manufacturers who are the biggest proponents or pre-manufactured materials such as MDF most often will include a line of plastic cabinet speakers in their portfolio. Plastics used to be reserved for low-end computer desktop speakers and the line of boom box radios. These products are usually found in low amplification, low fidelity applications. However, we are finding more and more home theater entertainment systems created from plastics. Space aged looking materials, finishes, and shapes dominate the market place. Virtually any shape can be economically molded from plastics. Depending on the resin used, a plastic speaker component can be molded for pennies. So, construction costs of the individual components are low. The problem with molding plastics is that you cannot create a thick walled product. Plastic molding requires thin and consistent wall thicknesses. A wall thickness of 1/10 of an inch is considered heavy. Once constructed, these components have a density much higher then the hardwoods. Combine thin-wall, rigid materials with the acoustic vibrations of a 100 Watt home theater system and you are sure to experience unwanted resonance of the speaker enclosures. The manufactures’ argument for MDF as a sound absorbing material is contrary to the use of plastics for cabinet design.
The answer can be found in the cabinet design itself. Real Wood Audio speaker systems use only high grade hardwoods with proper cabinet reinforcement techniques. Extensive volume and reflection calculations are performed using the highly proven math and audio formulas of Thiele & Small. Calculations are also performed to diminish internal reflection of sound waves while redirecting them in phase to the listening audience. These reinforcements are enhanced by expert woodworking joinery – both internal and external. Wooden cavities are sealed, dampened structurally, and internal vibrations are diminished with sound wave absorbing materials. From a purely aesthetics standpoint, the deep radiant beauty of real wood is second to none.
An acoustically “dead” speaker cabinet is one that does not create any sound waves on its own. A simple method of evaluating a cabinet is to wrap on it with your knuckles. If it sounds dead, it is. If it rings, or drums, then that cabinet will contribute to the sound waves emitted from the system. Mass is the other contributing factor. A speaker cabinet has to be of sufficient mass to let the speakers do the talking. The framework of a speaker needs to be held perfectly still while the cone is allowed to actuate unrestricted. Then why are violins and pianos made of thin-walled wood designed to resonate? The sound board of a piano and the body of a fine violin are made to resonate and amplify the tone of that instrument. Strings themselves won’t emit a lot of volume. It is the violin’s bridge that transmits string vibrations to the body. The body in turn, will resonate and amplify the tone you hear. A speaker cabinet could be made to resonate the way a violin does. However, the cabinet would then sound like a violin and promote only those tones within the instrument’s range. Speakers must have a far greater tone range than just a single violin or piano sound board and reflect the true tone of all the sounds it duplicates.
Sound is volume. True duplication of music envelopes the mind, body, and soul with sound. Sound has depth. Sound has feeling. Sound waves are transmitted through air. So, in order to fill the room with sound you must move the air. Small diameter speakers will emit sound, but it takes the large cone of a mid-range driver to move enough air so that the music actually envelops you – touches you. That’s why Real Wood Audio systems use full-sized cabinets and drivers for their front speakers. No wood veneers or fillers. Just real, solid hardwoods beautifully crafted to reflect the architecture of your décor. Each speaker is created by hand, one at a time, by experienced woodworking craftsmen and cabinet makers then expertly finished to deliver that warm glow and charm that only real wood can. Real Wood Audio uses old world woodworking techniques and joinery to create heirloom speaker cabinets that reflect the character of your listening environment. Real Wood Audio is created from the finest hardwoods with powerful, high-end speaker drivers that deliver sound waves from the lowest lows to the highest highs.
Real Wood Audio – designed to touch all of your senses.