XPRESS SPEAKER DIY-2
XPRESS DIY-2
If you are a music enthusiast, the only option open to you to enjoy good music-- unless you sing or play an instrument or two, or is married to a musician! -- is to have a hi-fi music system. This, as we all know, comprises three basic units-- a source, an amplifier and a pair of 'stereo' speakers. Speakers, as most of us have found out, have a personality of their own and are as different as individuals; or shall we say as different as their designers!
Though when we look at it from a tech angle, not much has changed from the 'electro-dynamic' speaker designed by Kellog and Rice at General Electric Company back in 1925. Their 'baby' was a nearly two-foot diameter moving coil speaker with a field coil to provide the driving magnetic force. The following decades saw 'express' developments in the audio field overall, and speaker driver development in particular. Very soon as permanent magnets became stronger and cheaper to produce, there emerged the era of the "modern" moving coil speaker as we know it today. Soon the AlNico magnets gave way to ferrite magnets, and the current trend is very powerful and smaller Neodymium magnets. I am not forgetting that some of the most expensive drivers on the planet these days sport ... yes, the good old field coil!
Ah, tech has a way of coming full circle, and that too in cycles. (A case in point, you will agree, is the resurgence of the vinyl LP.) Cone materials, which began with paper and its composites, soon made way for synthetic films, and as manufacturing tech advanced, moved to metallallised and later metallic film cones. Now the "hot trend" once again appears to be bamboo paper cones!
But one thing has to be admitted -- today a bewildering array of electro-dynamic drivers are available, ranging in size from a fraction of an inch to larger than the original Rice-Kellog driver, and ranging in price from the "cheap and cheerful" to the honestly unaffordable. The DIYer has no grounds for complaint; indeed he is overwhelmed by an embarrassment of riches! His choice is limited only by his need, his imagination, and of course, by his purse!
And the one thing that bridges these 'cheap and cheerful' transducers to the stratospherically priced "high end audio" drivers that cost an arm and a leg, is that, in the end, they all convert electrical waves into sound waves, just as Rice & Kellog's baby did so long ago! But with what fidelity is a moot point, though.
DIY Magical Realism
It is not an accident that the DIY enthusiast has invaded the rather esoteric field of speaker building as well. The more heartening fact is that the inspired designs of the better craftsmen among the DIYers have made the clan proud indeed. The individual hobbyist works flexibly within his budget; s/he has no constraints of time and labour -- both expensive stuff for a commercial operation to manage easily without cutting a corner or two or three. No wonder then people generally have migrated to the belief that DIY speakers most of the time offer better value than their commercial cousins.
Hi-fi as a hobby is more about the "feel good" factor of a good job done well with one's own hands. Being an Xpress DIY site, it is not for us to delve too deeply into theoretical stuff, dissecting a design and its USP. Rather, we tend to lean more towards the practical "how to" of achieving the results we set out to chase. Individuals pursue their hobbies not to participate in a competition, but rather to reap that unique satisfaction that comes with making something with one's own hands. Here is my watertight warranty -- your speakers are guaranteed to sound sweet, at least to your ears, no matter what--that is the lure and the very real magic of DIY!
To Wood, or No Wood ...?
Building speaker boxes (yes, most are boxes, often derisively called 'coffins' by the votaries of Open Baffle designs) from Day One, when such a one was dreamed up by a pioneer designer, meant hiring the services of an experienced carpenter. Proven expertise in wood working was a 'given' if one wanted to dabble in the art of speaker building. Till some wacky DIYers threw convention to the four winds and ventured boldly forth into uncharted territories, nobody dared to challenge the fine joinery work of the masters of wood artistry.
Though exotic materials have been used in the fabrication of speaker cabinets, ranging from carbon fibre to concrete to stainless steel, the commonest of stuff that goes into speaker cabinets is plain wood, or its modern incarnations like plywood, MDF, HDF etc. The fact that most of the speakers happen to be housed in one sort of box or another...small, medium, tall, narrow, huge... has all along been a strong deterrent for the average DIYer without wood working skills. It sure does not take a PhD to imagine how a "box" will look when made by the average "handyman"; rarely will it achieve proper "squareness" at least. Accept it, joinery is more an art that takes years of instruction and practice to master. Also, wood working needs space and at least some basic power tools and other machinery--both factors at a premium for the average enthusiast.
It was while "locked down" safely at home during the covid outbreak that my chafing mind and itching hands made some serendipitous discoveries. Yes, you don't need all that has been prescribed traditionally for experimenting with speaker boxes! And wonder of all wonders, you don't even need wood to do some "wood work"! Surely I broke the news to my group of 'crony hobbyists' and they too were more than enthused...rather, excited! What about tools? Yes, all you need is to be armed with the most basic of handyman tools to take up speaker DIY! Whoa, there ... !
Woodless Wood
The star of the venture is the synthetic avatar of good old wood. Don't be misled by the fancy names--there is no wood in Multi-wood or New-wood, or any such new-fangled "woods"; they are concoctions of plastics and God knows what else, and are touted as the best material for wet areas like kitchens and bathrooms. They come in an assortement of thicknesses and are sold in standard panel sizes like 8 x 4 feet. (You could sometimes persuade shop owners to sell you 4' x 4' offcuts too, which could suffice for a pair of small boxes like our first project. Get a sheet of 12 mm thickness which should see you through quit a few projects.)
For the speaker builder, however, they offer many plus points. Good damping, enough density to meet our acoustic requirements, and above all, absoultely easy "workability". You don't need smelly wood glue and nails or screws anymore. (In fact they are screw "unfriendly", but that's okay for us -- aren't we inventive!) All you need is a bottle of PVC pipe solvent cement and a couple of hours to achieve 'inseparable' joins. What more could you ask for?
Tooling Up
The average hobbyist is likely to have most of the tools needed here. If buy you must, get a set of basic tools of good quality. You need a large, strong box knife with blade lock, a Try square and a long steel ruler (24 inches), some emery cloth (50 grit for the 'rough work' and 150 or 200 grit for the fine work) and a bottle of PVC pipe solvent-cement. Invest in a few pairs of protective hand gloves that have a cut-resistant coating, and always wear your mask to protect your lungs. Exercise extreme care while using sharp tools. The larger boards could be cut on the floor (the ablest, stablest table perhaps!), with a cardboard carton piece below to buffer the knife blade.
Tricks of the Build
Wood or no wood, but here too you need to develop certain 'wood-working' skills. The most important is the use of a Try-square (the L-shaped tool) to mark and check right angles in panels and edges. Always check and re-check measurements and right angles to ensure right and proper fit and a 'square' build. With M-wood, all you need is am emery cloth wrapped around a small piece of wood (M-wood!) to rub and correct the edges and angles--taking out a few mm of M-wood is child's play, believe me; at the same time be careful not to take out too much in your new-found enthusiasm and nix your measurements.
The best 'wrinkle' with M-wood is that all you need is a large, sharp knife and lots of patience and care, to cut it accurately into the panels that will go to make up your speaker boxes. Be careful with sharp tools, and make your first cut with a straight blade and minimum force so that a straight line cut is made. Then score deeper a few times; you could now remove the steel ruler and follow the cut easily. Soon the knife blade will cut through. (Use a scrap piece of packing board below the cut.) Keep the knife straight and score repeatedly, rather than use brute force. It is a technique that you will soon master. Knife-cut edges are smooth--unlike saw cut ones, which need smoothening with sandpaper before they could be glued.
Once all the panels are cut and ready as per plan, it is time to start gluing them up in an orderly manner. The PVC solvent-cement is highly acidic and the fumes certainly are unhealthy, especially in closed spaces. So try to work in an open verandah, or near a window, with a desk fan pulling the fumes away from you to the outside. Use the built-in sponge to spread the solvent on both the mating surfaces (careful not to be too liberal and make it run!), wait a few seconds for the panel material to melt a little, and then hold the panels together firmly for about ten seconds--enough to effect a basic bond. Where possible, put a small weight on top to hold the bond under pressure for a few hours. Unlike pvc pipes, this takes longer to set fully and ensure a strong bond. It is best, IMHO, to work on one box partly, leave it aside for a while, and work on the second. This means both your boxes will be finished almost simultaneously. Before applying solvent cement, be sure to check and correct the mating surfaces for any gaps etc and ensure a proper right-angled joint. (You could save some of the white "sanding dust" and use it later as a good joint filler!)
Though when we look at it from a tech angle, not much has changed from the 'electro-dynamic' speaker designed by Kellog and Rice at General Electric Company back in 1925. Their 'baby' was a nearly two-foot diameter moving coil speaker with a field coil to provide the driving magnetic force. The following decades saw 'express' developments in the audio field overall, and speaker driver development in particular. Very soon as permanent magnets became stronger and cheaper to produce, there emerged the era of the "modern" moving coil speaker as we know it today. Soon the AlNico magnets gave way to ferrite magnets, and the current trend is very powerful and smaller Neodymium magnets. I am not forgetting that some of the most expensive drivers on the planet these days sport ... yes, the good old field coil!
 |
| The Rice-Kellog patent drawing |
 |
| Rice and Kellog with their 'baby' |
Ah, tech has a way of coming full circle, and that too in cycles. (A case in point, you will agree, is the resurgence of the vinyl LP.) Cone materials, which began with paper and its composites, soon made way for synthetic films, and as manufacturing tech advanced, moved to metallallised and later metallic film cones. Now the "hot trend" once again appears to be bamboo paper cones!
But one thing has to be admitted -- today a bewildering array of electro-dynamic drivers are available, ranging in size from a fraction of an inch to larger than the original Rice-Kellog driver, and ranging in price from the "cheap and cheerful" to the honestly unaffordable. The DIYer has no grounds for complaint; indeed he is overwhelmed by an embarrassment of riches! His choice is limited only by his need, his imagination, and of course, by his purse!
And the one thing that bridges these 'cheap and cheerful' transducers to the stratospherically priced "high end audio" drivers that cost an arm and a leg, is that, in the end, they all convert electrical waves into sound waves, just as Rice & Kellog's baby did so long ago! But with what fidelity is a moot point, though.
DIY Magical Realism
Hi-fi as a hobby is more about the "feel good" factor of a good job done well with one's own hands. Being an Xpress DIY site, it is not for us to delve too deeply into theoretical stuff, dissecting a design and its USP. Rather, we tend to lean more towards the practical "how to" of achieving the results we set out to chase. Individuals pursue their hobbies not to participate in a competition, but rather to reap that unique satisfaction that comes with making something with one's own hands. Here is my watertight warranty -- your speakers are guaranteed to sound sweet, at least to your ears, no matter what--that is the lure and the very real magic of DIY!
To Wood, or No Wood ...?
Building speaker boxes (yes, most are boxes, often derisively called 'coffins' by the votaries of Open Baffle designs) from Day One, when such a one was dreamed up by a pioneer designer, meant hiring the services of an experienced carpenter. Proven expertise in wood working was a 'given' if one wanted to dabble in the art of speaker building. Till some wacky DIYers threw convention to the four winds and ventured boldly forth into uncharted territories, nobody dared to challenge the fine joinery work of the masters of wood artistry.
Though exotic materials have been used in the fabrication of speaker cabinets, ranging from carbon fibre to concrete to stainless steel, the commonest of stuff that goes into speaker cabinets is plain wood, or its modern incarnations like plywood, MDF, HDF etc. The fact that most of the speakers happen to be housed in one sort of box or another...small, medium, tall, narrow, huge... has all along been a strong deterrent for the average DIYer without wood working skills. It sure does not take a PhD to imagine how a "box" will look when made by the average "handyman"; rarely will it achieve proper "squareness" at least. Accept it, joinery is more an art that takes years of instruction and practice to master. Also, wood working needs space and at least some basic power tools and other machinery--both factors at a premium for the average enthusiast.
It was while "locked down" safely at home during the covid outbreak that my chafing mind and itching hands made some serendipitous discoveries. Yes, you don't need all that has been prescribed traditionally for experimenting with speaker boxes! And wonder of all wonders, you don't even need wood to do some "wood work"! Surely I broke the news to my group of 'crony hobbyists' and they too were more than enthused...rather, excited! What about tools? Yes, all you need is to be armed with the most basic of handyman tools to take up speaker DIY! Whoa, there ... !
Woodless Wood
The star of the venture is the synthetic avatar of good old wood. Don't be misled by the fancy names--there is no wood in Multi-wood or New-wood, or any such new-fangled "woods"; they are concoctions of plastics and God knows what else, and are touted as the best material for wet areas like kitchens and bathrooms. They come in an assortement of thicknesses and are sold in standard panel sizes like 8 x 4 feet. (You could sometimes persuade shop owners to sell you 4' x 4' offcuts too, which could suffice for a pair of small boxes like our first project. Get a sheet of 12 mm thickness which should see you through quit a few projects.)
For the speaker builder, however, they offer many plus points. Good damping, enough density to meet our acoustic requirements, and above all, absoultely easy "workability". You don't need smelly wood glue and nails or screws anymore. (In fact they are screw "unfriendly", but that's okay for us -- aren't we inventive!) All you need is a bottle of PVC pipe solvent cement and a couple of hours to achieve 'inseparable' joins. What more could you ask for?
Tooling Up
Tricks of the Build
Wood or no wood, but here too you need to develop certain 'wood-working' skills. The most important is the use of a Try-square (the L-shaped tool) to mark and check right angles in panels and edges. Always check and re-check measurements and right angles to ensure right and proper fit and a 'square' build. With M-wood, all you need is am emery cloth wrapped around a small piece of wood (M-wood!) to rub and correct the edges and angles--taking out a few mm of M-wood is child's play, believe me; at the same time be careful not to take out too much in your new-found enthusiasm and nix your measurements.
The best 'wrinkle' with M-wood is that all you need is a large, sharp knife and lots of patience and care, to cut it accurately into the panels that will go to make up your speaker boxes. Be careful with sharp tools, and make your first cut with a straight blade and minimum force so that a straight line cut is made. Then score deeper a few times; you could now remove the steel ruler and follow the cut easily. Soon the knife blade will cut through. (Use a scrap piece of packing board below the cut.) Keep the knife straight and score repeatedly, rather than use brute force. It is a technique that you will soon master. Knife-cut edges are smooth--unlike saw cut ones, which need smoothening with sandpaper before they could be glued.
Once all the panels are cut and ready as per plan, it is time to start gluing them up in an orderly manner. The PVC solvent-cement is highly acidic and the fumes certainly are unhealthy, especially in closed spaces. So try to work in an open verandah, or near a window, with a desk fan pulling the fumes away from you to the outside. Use the built-in sponge to spread the solvent on both the mating surfaces (careful not to be too liberal and make it run!), wait a few seconds for the panel material to melt a little, and then hold the panels together firmly for about ten seconds--enough to effect a basic bond. Where possible, put a small weight on top to hold the bond under pressure for a few hours. Unlike pvc pipes, this takes longer to set fully and ensure a strong bond. It is best, IMHO, to work on one box partly, leave it aside for a while, and work on the second. This means both your boxes will be finished almost simultaneously. Before applying solvent cement, be sure to check and correct the mating surfaces for any gaps etc and ensure a proper right-angled joint. (You could save some of the white "sanding dust" and use it later as a good joint filler!)
M-wood, despite its many advantages, has very poor screw holding ability. So for mounting speaker drivers, we have to resort to 'claw Tee nuts' and bolts. An easy ploy I adopted was to superglue the nut to a fairly large washer and then stick the washer onto the M-wood panel using either superglue or even pvc cement. Use moderate pressure while tightening the driver, which anyway is advised so that you don't damage the precious driver. Drilling holes in M-wood needs nothing fancier than a simple hand drill. Mounting the speaker cable connectors in the back is not as involved as mounting the driver--simple wood screws will hold the terminal plate securely.
So much for the build "mechanics".
And now full steam ahead onto our projects mates!!
* * * * * * * * * * * *
So much for the build "mechanics".
And now full steam ahead onto our projects mates!!
* * * * * * * * * * * *
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