ya im sorry. i was reffering to the 85L box. but im gonna try to cut as close as possible to an straight edge. i thought that if its not staright, it would effect the frequency or sound output. other than that ive got everything staright forward. i only need to buy couple tools and i should be ok.
finsih, i think im gonna go with veneer because it looks easier. and atlas is final i think for the driver. im gonna start everything start of next month.
finsih, i think im gonna go with veneer because it looks easier. and atlas is final i think for the driver. im gonna start everything start of next month.
I'm not sure if you're a noob when it comes to woodworking or not (sorry if you aren't), but using a guideboard makes it easy to do straight cuts with a jigsaw. Just nail a straight board along the line of your cut using finishing nails, and saw down that.
Again, sorry if you already knew this, but it actually took me longer than I would have liked to figure this out.
Again, sorry if you already knew this, but it actually took me longer than I would have liked to figure this out.
Good suggestion about the jigsaw guide.
I've been running some simulations on WinISD. I wasn't so sure about the Atlas 12 at first, as Shiva was showing better response curves in the EBS box. However, the mid-Qts option (short the gold terminals with 1.5ohm resistor) is producing some nice results.
I've been running some simulations on WinISD. I wasn't so sure about the Atlas 12 at first, as Shiva was showing better response curves in the EBS box. However, the mid-Qts option (short the gold terminals with 1.5ohm resistor) is producing some nice results.
A five watter should do. There are some tradoe-offs in power handling and efficiency, though. Here is a link to an article describing the operation:
http://www.adireaudio.com/Files/TechPapers/RDOOperation.pdf
http://www.adireaudio.com/Files/TechPapers/RDOOperation.pdf
Jigga, once you decide on a box design, draw it all up on a piece of paper to make a 'cut sheet' showing how you're going to cut all of the pieces from the 8x4 or 5x5 and take it to a cabinetmaker/kitchen place and have them cut all of the pieces to size for you on a large saw table. You'll get MUCH more accurate results and it will only cost a modest amount and save a ton of time and hassle. Think about how to do it carefully and explain to the guy doing the cutting what you actually want to do with all the panels and let him wrk out the logistics of the cutting. For example, all 4 sides of a stereo pair could be rough cut, then finally dimensioned on the saw all at once, so they're all the same size. Ring around in the yellowpages in your area and ask if they'll do it and how much it'll cost for a cash job.
It looks like a 39cm long, 10.20cm diameter tube gives a better response with the Atlas 12. 45cm looks even better (lower group delay) but might introduce port turbulance. You will have to adjust the length for the flared ends.
Watch out for cuts at Home Depot. If the dimensions aren't correct the whole box will be off. As Brett said, it can be a real headache.
To simon5 (or others): You seem pretty familar with WinISD, is there a feature that warns of audible vent noise?
Watch out for cuts at Home Depot. If the dimensions aren't correct the whole box will be off. As Brett said, it can be a real headache.
To simon5 (or others): You seem pretty familar with WinISD, is there a feature that warns of audible vent noise?
Just happened on this thread and noticed mention of the Shiva, etc. Back when the Shiva was undergoing development with input from the old Bass List forum, I mentioned an idea that I'd been noodling around with for 20+ years, namely using a second voicecoil to adjust the "Q" of the driver with a variable resistor. Well, Dan Wiggins picked on that and was able to translate it into a readily useable reality. BTW: it works pretty good.
If you plan on building a downfiring sub with the Shiva, you'll need to have at least 3.5 inches of clearence between the bottom of the driver/cabinet and the floor. If you have thick shag carpets you may want to increase the distance to take into account the thickness (nap) of the carpet. IOW: you want 3.5 inches of unobstructed clearance. As a matter of fact this distance is a very good "rule-of-thumb" dimention for any of the competing 12" sub drivers used in a downfiring configuration.
I don't know how any of the various sub drivers stack up when it comes to being used in a downfiring configuration, but the Shiva was deliberately designed to be usable in this orientation and there are very specific issues that come up that are not always addressed by other manufacturers.
As concerns Plywood versus MDF, I'd say that plywood (void free) will probably work just fine, I've heard 15 and 18 inch subs in plywood cabinets and as long as they were well constructed (usually with one internal shelf brace) I've never heard anything that I could pick up as a resonance. Never one to leave anything to chance I've always tended to overbuild, but I don't have to move them often. My favorite for many years is to use a layer of high density particle board (not MDF) as an inner layer and plywood as the outer layer. Very low tech and gives an extremely dead enclosure, which is just what you need. Another method, that was developed by Ed Heath on the Bass List, is to build your cabinet out of plywood, assemble the drivers,etc., and play your test tones thru it while listening to the cabinet through a mechanic's stethoscope to locate any resonance. Be sure to mark the locations that conveyed resonance with bits of masking tape or whatever. When you're done then pull the driver and apply oil-based modelling clay to the corresponding point that you marked, that is, on the inside of the cabinet. Works like a dream, stays put once applied and doesn't ever dry out (it must be oil-based modelling clay, accept no substitutes!). You can "mass-load" the clay even further by adding lead buckshot to the clay, #9 works well.
Anyway, I hope some (or all) of this is useful.
Best Regards,
TerryO
designer/builder of Shiva #1 (it's downfiring!)
If you plan on building a downfiring sub with the Shiva, you'll need to have at least 3.5 inches of clearence between the bottom of the driver/cabinet and the floor. If you have thick shag carpets you may want to increase the distance to take into account the thickness (nap) of the carpet. IOW: you want 3.5 inches of unobstructed clearance. As a matter of fact this distance is a very good "rule-of-thumb" dimention for any of the competing 12" sub drivers used in a downfiring configuration.
I don't know how any of the various sub drivers stack up when it comes to being used in a downfiring configuration, but the Shiva was deliberately designed to be usable in this orientation and there are very specific issues that come up that are not always addressed by other manufacturers.
As concerns Plywood versus MDF, I'd say that plywood (void free) will probably work just fine, I've heard 15 and 18 inch subs in plywood cabinets and as long as they were well constructed (usually with one internal shelf brace) I've never heard anything that I could pick up as a resonance. Never one to leave anything to chance I've always tended to overbuild, but I don't have to move them often. My favorite for many years is to use a layer of high density particle board (not MDF) as an inner layer and plywood as the outer layer. Very low tech and gives an extremely dead enclosure, which is just what you need. Another method, that was developed by Ed Heath on the Bass List, is to build your cabinet out of plywood, assemble the drivers,etc., and play your test tones thru it while listening to the cabinet through a mechanic's stethoscope to locate any resonance. Be sure to mark the locations that conveyed resonance with bits of masking tape or whatever. When you're done then pull the driver and apply oil-based modelling clay to the corresponding point that you marked, that is, on the inside of the cabinet. Works like a dream, stays put once applied and doesn't ever dry out (it must be oil-based modelling clay, accept no substitutes!). You can "mass-load" the clay even further by adding lead buckshot to the clay, #9 works well.
Anyway, I hope some (or all) of this is useful.
Best Regards,
TerryO
designer/builder of Shiva #1 (it's downfiring!)
Thanks, Terry. The Atlas 12 falls within Dan's downfiring sag calculation (1.988mm), so I guess it will work fine. Really interesting technique with the clay for deadening box resonances.
To JiggaD369: I don't have an AOL instant messenger account. I can probably set one up, but I am housesitting for a friend this week and will have limited access to a computer. You can email me directly through the address in my profile if you want.
Another option for the enclosure is a sonotube (sonosub). Not sure if your are familar with the design, but basically you just use a sonotube (concrete form) with capped ends and some bracing inside. Makes for an easy enclosure, and many people seem to like the design. A forum search for sonosub or sonotube will probably turn up some examples. Adire's commercial take on the style can be found at their website http://www.adireaudio.com/ The model (Sadhara) is the big tube on the opening page. It is an unconventional look which you may or may not like. I would guess that you would need an 18" diameter section about 35" long (or less) to reach 142.5L + shelf bracing. Kinda tall, but with a smaller footprint.
To JiggaD369: I don't have an AOL instant messenger account. I can probably set one up, but I am housesitting for a friend this week and will have limited access to a computer. You can email me directly through the address in my profile if you want.
Another option for the enclosure is a sonotube (sonosub). Not sure if your are familar with the design, but basically you just use a sonotube (concrete form) with capped ends and some bracing inside. Makes for an easy enclosure, and many people seem to like the design. A forum search for sonosub or sonotube will probably turn up some examples. Adire's commercial take on the style can be found at their website http://www.adireaudio.com/ The model (Sadhara) is the big tube on the opening page. It is an unconventional look which you may or may not like. I would guess that you would need an 18" diameter section about 35" long (or less) to reach 142.5L + shelf bracing. Kinda tall, but with a smaller footprint.
NO! Get it cut somewhere with a large accurate table by someone who knows what they're doing. The extra $ spent will be well worth it come time to fit it all together. The guy I use is brilliant, and based on the work he's done, I could build flatpack kits and be confident they'll screw together perfectly at the customer end.JiggaD369 said:
na i think im gonna go with the original design. i dont wanna go too high tech. i think that design from the white paper is pretty easy as i now fully unsderstand the concept of it. im gonna go with mdf and use liquid nails for the inside edges so not a single buff of air leaks thru it. i made a box for my car before and used the same technique and it worked damn good. i called Lowes yesterday and they said a sheet of 8'x4' is $24 and thats cheap. ill see how they cut their wood there.
so you guys think that the 12" Atlas will work good with the 1.5 ohm 5w resistor in that enclosure? because i wanna make it final as i will start the project in couple weeks.
so you guys think that the 12" Atlas will work good with the 1.5 ohm 5w resistor in that enclosure? because i wanna make it final as i will start the project in couple weeks.
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