Building a Home Recording Studio
D.I.Y. Studio Door
Building a soundproof studio door
Until quite recently the recording of music was the domain of the professional studio but the advent of high quality semi-pro multitrack machines and, more recently, the cassette-based systems, have changed all that. Nowadays minor works of art are regularly created in anywhere from a bedroom to a garage. Nature however being what it is, all of the advances in electronics cannot overcome the basic stumbling block of recording via a microphone; that is the presence of extraneous noises and the effect of the room itself on the sound. In both of these cases it is necessary for the amateur to adopt similar solutions to those used by his professional counterpart and, whilst matching those standards is impossible, creditable results are possible even on a very low budget.
Soundproofing is a virtually never ending process, to which the law of diminishing returns applies, consequently quite substantial reductions in level are possible initially and it is these which represent the best value to the home studio operator. The starting point for a studio should be the largest 'quiet' room available, preferably one without any of the walls adjoining a noisy room or area, including those belonging to neighbours. It is obvious that the main problem points are the doors, windows, ventilators, and in some cases, the chimney.
Starting with the door which on modern houses offers about as much resistance to the passage of sound as it does to the shoulder of a thief, and for this reason a double door is essential. In addition to its acoustic worth the door also offers the added advantage of increased security since it will open outwards and be more substantial in its construction. There is little point in going out to buy a duplicate door because the aim is to reduce the door's sound transmission value to that of the wall, and that entails using a custom built sand and cement filled door, but one which is simplicity itself to construct and will most certainly cost less than its inferior counterpart.
The first step in its construction is to measure the internal dimensions of the door frame at the point where the door will be hung, and reduce them to allow for free opening - a ¼ inch reduction in width is adequate and the length must be reduced to clear any carpets. This is the size to which the ¾ inch or 1 inch thick chipboard is ordered. (Most D.I.Y. shops offer a cutting service - take advantage of it as it will save a lot of mess and effort). The cut sheet is checked against the door frame for accuracy of fit and then laid flat, the door is now built up on this base. A perimeter frame of softwood is cut to size, glued and nailed into place. A small 'box' is constructed around the lock area and depending upon the type of hinges to be used (large T hinges are recommended), support ribs are glued and nailed into place (see photo 1).
When the glue has set, the door is fitted with its hinges and hung in place in the frame. The reason that the door is hung at this stage is because the weight of the finished door is such that considerable difficulty is experienced when trying to manoeuvre and hold the complete door whilst driving the screws home (a problem discovered the hard way). The door is once again laid flat and prepared for sand filling. There is little point in having a sand filling if, when the door is lifted, it falls and packs towards the base of the door, reducing its effectiveness and perhaps causing the door to bulge. To prevent this, corrugated cardboard is cut into strips which are slightly narrower than the perimeter depth. When sufficient strips have been cut to completely pack the door cavity, the chipboard is covered in a thick mix of heavy duty wallpaper paste and the strips are now packed end on into place against it - the paste sealing one end of the corrugations. Nails may be used to keep the strips upright whilst packing and to provide a key to the door surface (see photo 2).
The next task is to fill the door, this involves pouring sand evenly over the entire door area so the sand must be selected such that the grain size is small enough to allow it to fall easily into the tubes formed by the corrugations. Once the tubes are full, they are sealed off by trowelling a thin layer of cement across the surface, this layer is later brought up to the level of the frame - a straight edge across the frame will provide an accurate depth guide. The cement layer further deadens the door. All that remains to be done at this point is to fit the inner skin. This may be of ½ inch chipboard though in practice a hardboard skin seems adequate providing that a central support is fitted.
Prior to the development of the sand filled system a papier mache filling composed of newspaper and cement was tried. This proved successful but had its drawbacks, one being the time taken to tear the newspaper, though this could be overcome by acquiring the output of an office shredder. Another and probably the greatest disadvantage, is the water content of the mache - it takes such a long time for the moisture to be completely driven off and sealing the door before this process is complete, will at best affect the paint and at worst warp the door.
The door is now returned to its position in the frame and a lock or latch is fitted. With the new door latched and the inner door open a sealing frame is glued and nailed into position on the original frame. It should be a flush fit against the new door; a threshold which accurately fills the gap between the two doors is fitted. Finally foam draught excluding strip is applied completely around the frame to provide an effective seal for both the new and old doors, but it may be necessary to apply the sealing strip to the door edge instead of the frame on the hinge side.
With both doors closed, the improvement is obvious, it is also equally obvious why studios are rarely rooms with a view now that the sound entering through the window can be assessed. But how that can be cured is another story!
Feature by Steve Taylor
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