Once the contact cement has dried for the recommended 40 minutes or so just lay them out and then beginto place the sheet of veneer over the work and then pull them out one at a time. Lining of the TQWT's sides is useful for prevention of reflections from side to side of expanding pipe (horn). It is square 8-3/4" plus twice material thickness by 8-3/4" plus twice the material thickness. The only thing that didn't turn out as well as I had hoped was the top of the back panel on both speakers. The bottom line is Miraflex® and polyfill are one-for-one replaceable. JA8008 used in open baffle constructions: OBL-15, the successor of OBL-11, now with the new JA8008-HMQ driver OBL-11, Open Baffle Loudspeaker. My professional past: Audio engineer for German TV and Film, Carpentry contractor, cabinet maker, audio engineer for archival recording in Philadelphia. Some day I might carefully add a little tweeter using a film cap to couple it in, just to see if I really miss it. I found the speakers to sound the best to me with a toe in so the intersection was about a yard or so in front of my couch. The only thing that I did differently is in the cutting of the rectangular port on the bottom of the pipe; I left out the 3/8" lip on the bottom, and installed a 3/4" base instead. Both will be painted satin black for contrast with the natural wood. Finally, the cabinet is lightly stuffed with polyfill, from the top down to just below the level of the driver. Installing the base. I think these equations are for a fully stuffed pipe, because mine seems to drop off around 55Hz, and it's about 60% stuffed. One good example of a spherical speaker is the Gallo Nucleus Solo above on the left which is made of rolled steel or brass. There is a comprehensive study on TQWT with additional helmholz resonators writen by Jack Jakulis (Word 97 format). With that in mind, the option was to use a design first introduced by Paul Voigt in 1930, known as the TQWT or Voigt Pipe that integrates the 1/4 wavelength pipe length design used in transmission lines but with a different approach to improve bass response. They do have awesome low frequency characteristic that I hoped the Voigt pipe would bring out. You all are pros. They can be built of Baltic birch veneer plywood with mdf trim, as shown here, for less than $250. When I added any length to the port tube at all the driver lost nearly all the mid/bass and with it out completely the driver sounded sloppy. The following section describes some lessons learned that I hope you find helpful. I have seen other versions of this pipe with the units mounted on the sloping side, rather than the vertical one and I have tried it with the cabinet aligned as such, but find that as you might expect - the sound is upward firing...great if you stand up while listening! To move the speaker to the left wall, you must specify a negative value . Ok. I used Silicon glue for that. The article also said that the hardest material like cultured marble would be best for the boxes so I went out and got some 8" x 8" x 24" chimney tile (flue liner) and wanted to cut round holes in the sides of it. Cut the sides from a single piece of shelving. Hold it there and let your partner draw a line along the steel wire. The driver is usually positioned close to the middle of the baffle or slightly lower. There were many dicussions where this should be aplied. If you have difficulty with that shape take a piece of spring steel wire and bend it in a curve that touches the sides of the rectangle in a gentle slope almost coinciding with the sides near the corners. Save the scrap piece. The midrange definition and presence is amazing. I put a 1/2" chamfer on the edges, just because. My guess is there's a glob of caulk stuck to the top of the box stalactite style. All five speakers use a single Radio-Shack 8" 35-Watt full-range driver. Mark this side "Inside". This is pretty much for cosmetics only, so put what ever edge treatment you want. The painted port baffles and toilet seats (driver baffles). Make the driver cutout . Since it is a good idea to place the speakers off center in a baffle and because the scrap plywood I had offered that shape I made those baffles looking a little like wings pointing toward the middle of the sound stage. Since this is intended to be a full-range, single speaker sound source, the type of speaker chosen is rather critical. Use it instead of wood filler ... it's faster, smoother, can be sanded out if you screw it up and re-done. The Voigt Pipe acts as a cross between a horn and a transmission line. It's hard to tell from this picture, but the back of the base is only 1/2" behind the back of the enclosure. The floor center point, from left to right is in the same position as the usual set-up....i.e. The Voigt Pipes are allowed in the living room now in spite of their unfinished surfaces and we enjoy them. Put a zobel (6.8uF cap in series with 8ohm resistor) in parallel with the driver. This procedure should provide a deep and tight bass with a pretty even response. If memory serves me, they are superior to the Diatones I built by a fair margin, although both speakers shared many of the same advantages, the pipes being much better in the bass and throwing a much larger stage. Pipe Inner Diameter (inch) This is the inner diameter of each tuning port. A few years ago /u/datums wrote a series of posts on speaker design. Here you'll find an explanation about the Voight-Pipe's design (also called a TQWT or Tapered Quarter Wavelength Tube design). ... Work: Classic Valve Design. Glue and screw the one piece of MDF to the bottom of the pipe, then glue and screw the second piece of MDF to the first. I was bent on building both pipes from one sheet, so mine are only 7.5" wide and 9.5" deep (I wanted to preserve the 7 degree angle that Jeschke used). You may also view my notes and calculations, but these are worse then the ones above! I found the design in February of 2002 while co-oping in California, but I didn't have time to build them until I was back home in Massachusetts. At first, I stripped the wood using a handheld circular saw. Its relatively low adoption in commercial speakers can mostly be attributed to the large resulting dimensions of the speaker produced and the expense of manufacturing a rigid tapering tube. See more ideas about speaker cab, speaker, speaker plans. The only way to reduce these line resonances is to stuff the line severely, which changes air speed and therefore acts as prolongated line, but at the same time kills efficiency. But that in NOT why I have it presented here. To find the holes for the machine screws you may want to make a template of the layout before you veneer so you can use a hand drill to re-drill through the veneer. I used liquid nails and tub caulk to glue and seal the boxes, with a few nails in the back panel. My homage to Gilbert A. Briggs' SFB OB-09, open baffle construction, JA8008/TW034 and Eminence Deltalite II 2515, 15" bass driver OB … My challenge was adapting these designs to work with pine that is 0.75 inches thick. Voigt's audio inventions. This method is usually applied in transmission line designs, where theoretic principle derives from long lossy pipe. This will assure that everything will be square. Use 3/4" ply or MDF. The backs were hinged so that I could adjust stuffing, felt, etc. To get a smooth furniture finish the varnished cabinet must sit for 72 hours, after which I will lightly sand it with #220 paper and apply one final coat. Per box, including behind the driver. Make your own Subwoofer Box Design. I figured that the pipe could augment the bass response only so much, and I would have to reduce the midrange response somewhat anyway by 'hardstuffing' the pipe and flattening the 'humps'. Build the plinth for the bottom. I selected some Streetwire 14 gauge stranded OFC tinned wire. Cone material is doped paper and the wizzer is also what looks like some sort of treated paper - though stiffer. Along came summer 1999 and time passed with other predilections. So, one day I took the time to follow every link and lead I could find via Google and I copied text and images to my local web site. than some love potion?? Nothing at all in the lower section. Continue the cut line the full length of the board. These are crossed over at about 12khz using a 1.5uF film & foil capacitor and a very small air core inductor (2nd order crossover) and are attenuated to a relatively soft level. I may try making one three-sided with all sides being triangular (different-sized triangles?). The round speaker mounting baffle will be bolted on to enable me to substitute different size drivers by changing to a different baffle. The high frequency extension was a little weak, but thats what my plasma tweeters are for. TQWT's TL behavior offers a nice acoustic load for the driver over most of it's operating range and in addition the bass reflex reinforcement can be tuned pretty low so that a pretty deep and tight bass can result. It should be vertical to the front panel and coincide with the speaker axis. After the glue sets, I remove the screws and plug the holes with light-weight spackling. Take about a foot of 2" by 3" lumber and slice it in two pieces lengthwise but at an 7 degree angle. I used tung oil but I think Lacewood wants a high gloss ... with less than perfect sanding to start due to the grain and lots of coats with sanding between. Put the back between the shelves, align the cut line with the top edge of one of the shelves and clamp both ends. With the driver chosen I did a search on the internet for existing plans in hopes of finding a fellow DIY'er that has figured everything out for me. Align the inside edge of the back with the bottom of the sides. Who really uses bi-wiring anyway. The best solution is to install a baffle step correction circuit. I used about a l ½ lbs. Because of this, the Voigt pipe can produce a very wide frequency range with very natural tonal balance. This design gets the benefits of a spherical design, but also adds a tapered tube at the back to eliminate all internal resonances. Cut it with a hacksaw and cut a slot for the screw driver in the outer end. Any reservations that on me may have about them, and yes they are not perfect but what faults that do exist are benign in their presence. I love the single-speaker wide-bandwidth sound now. Drill a 1/2" hole behind the speaker through the back panel. I drew that curve by hand on one baffle and copied over to the other baffle. This is important! The cabinet is now complete. I can only guess that any remaining sound waves that may have been reflected back up the Pipe are damped by this. But it was the anticipation of listening when I was coming home every day that made me think of what was happening here. 8.5 Combinations It is possible to combine various pipe geometries. Next, I lined all four sides of the cabinet with yellow Fiberglas®. I ended up only using one dowel to stiffen the 'middle' of the sides below the driver. You simply drag it around the edge and bingo ... perfect edge just waiting for a quick sand. The efficiency is very high and the sound less coloured than typical horns. NOTE: The baffle is glued to the rest of the cabinet AFTER the cabinets is lined and stuffed. This is what its about....fun! The sound level demands for side and rear speakers in a music surround system with ambience extraction are not severe. Mechanical failure can occur when the drive signal demands movement from the speaker coil that exceeds the design … ), I decided that the Voigt pipe would be the way to go. Seas Speaker Kits, Speakers & Drive Units, Prestige & Excel ranges. Get primer in spray cans! The same theory was applied to the stuffing; fiberglass insulation is cheap and available at Home Depot. I needed some speaker stands for my home studio recently, but didn't want to pay retail for them. I had chosen the hurricane nuts to use on the back side of the panel for putting the mounting machine screws into. Place the baffle on your work bench inside up. I think next time I'll use plywood. The pvc pipe speakers look great. Only the side pieces are tapered or actually one rectangle cut diagonally into two triangles. I was hearing more and more and the excitement was there - complete with the goosebumps! from the Lowther Club of Norway: (partial quote). A Folded Tapered Quarter Wave Pipe using the Fostex FE-167E Full Range Driver Rear View Built by Richard Goodland I used some sophisticated tools cause I have them, but all the cutting for this project can be done with an inexpensive circular saw ($40 at Home Depot). long and the width of the box) and just using a staple gun to secure it. The port baffle is decorative. Loosely assemble the whole pressure screw jig and find out the screw length you need. The triangular nature of the Voigt pipe causes its resonant frequencies to be spread across the midrange bands, and the length of the pipe accentuates the bass frequencies very well.
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