I've had my dual tempests now for quite a long time (for me anyway) and I've got the itch to build something again so I've decided to redo my subs. Currently my low end is being provided by two subs that are about 220L in size and ported to 17 hz. Each one is loacted in the front corner of my HT behind the curtain and are getting 200 watts from my rotel power amp. They sound pretty good and do rumble the basement but they simply don't give me the raw punch I want and they're not the greatest for music so I generally turn them off for 2 channel. So what to try next? Well what first got me thinking was that 1803 blueprint driver that's being sold in the for sale area but after thinking about it I decided that as great a driver as it is I would be better off going down the 12 shiva's danceing route. So with that in mind I placed an order last night with bob at http://www.creativesound.ca for another pair of tempests that I'm going to install into the common wall between the HT and the shop. When I first built the HT room I tried running dual tempests in an IB but that project failed for several reasons being poor quality power and a wrongly designed baffle. I've got better power now and I'm going to fix my baffle this time and I'm also going with twice the number of drivers:yesnod: The common wall between my shop and the HT is shoddy at best and in hindsight I should have torn it down when I built the HT but budget was tight was it was at the time so I choose to leave it as it was. The issue is that its just 2 * 3 studs with 1/4" paneling over it so it tends to vibrate easily if the IB is coupled directly to it. Strangely enough the subs in the room don't seem to vibrate it anywhere near as much even when really going...though I have stiffened the wall up significantly since the IB days. Anyway this time round what I'm planning on doing is having a full 3/4" sheet of MDF ripped in half so that I end up with two 2 feet by 8 foot boards that I'll glue together to get a 1.5" baffle. I then plan on cutting out the first 2 feet of the wall from the front wall and then installing this baffle directly to the floor, side stud on the wall and the wooden I beam at the ceiling to give it a very solid footing. I figure I can then caulk the joint between this baffle and the rest of the wall to stop the front and rear waves from interfereing with each other and at the same time limit the coupling of the baffle and the common wall. The four tempests will then be mounted into the baffle with the drivers all fireing forward into the room and wired in // and series to give me two 8 ohm loads for each pair of drivers. For the time being that will mean I'll only be sending each pair 120 watts but that should hold me over till I can afford a real sub amp to do these justice.
My new sub project
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I figure I can then caulk the joint between this baffle and the rest of the wall to stop the front and rear waves from interfereing with each other and at the same time limit the coupling of the baffle and the common wall.
Save yourself the time and trouble, just screw the baffle to the studs that way it can easily be removed if necessary.
theAudioWorx
Klone-Audio
IB subwoofer FAQ page
"Complicated equipment and light reflectors and various other items of hardware are enough, to my mind, to prevent the birdie from coming out." ...... Henri Cartier-Bresson- Bottom
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why not use a manifold design? that way the forces cancell most wall vibration-it's somewhat simpler/smaller and you could do 2x pairs or all 4 in one manifold-just seems like a better choice to me -unless you plan on running them up past 80-100 hz
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"The appreciation of music is subjective.The reproduction of music isn't."-Bill Dudleston=+=+=+=+=+=+=
"The appreciation of music is subjective.The reproduction of music isn't."-Bill Dudleston- Bottom
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Rob I've thought about that but coupleing the manifold to the side studs caused a lot of vibrations the last time which was why I thought about doing it this way so that I would replace that section of the wall with something more sturdy. I guess I could still do a manifold and install a new section of the wall but is it really worth it over a straight liine array?
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Andrew, this isn't exactly my forte' but could you use some heavy rack mount type of arrangement and attach (why doesn't attach look like it's spelled correctly?) the baffle to the vertical risers of the rack?
Note, I'm not talking about some wimpy little 22 guage steel rack that it's manufacturer would have you believe is an industrial strength item, I mean something made out of 4" channel iron, hilti'd to the concrete floor by it's foot brace and tied above to the ceiling (floor joists), or just anchored to the floor, for that matter. I'm sure you could extend your drywall and studs to meet up with an industrial rack and still look good.
I have a specific rack in mind, you have my address...- Bottom
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Andrew
Using a manifold will place significally less stress on that studs/wall, as compared to a line array.
theAudioWorx
Klone-Audio
IB subwoofer FAQ page
"Complicated equipment and light reflectors and various other items of hardware are enough, to my mind, to prevent the birdie from coming out." ...... Henri Cartier-Bresson- Bottom
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Ok if I go for a manifold desing is theer any difference between building say a 19" square box with drivers on the top, bottom, and sides vs building a box that's 32" tall and 14" wide with two tempests on each side? If I go narrow it might fit between the existing studs which could make the install easier. I'd then have a hole that's 32" by 14" on the HT side...is that a problem?
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Andrew
Stacking 2 drivers on each side is fine.
The only thing gained by having one driver on each side of a cube, is a smaller opening into the room.
theAudioWorx
Klone-Audio
IB subwoofer FAQ page
"Complicated equipment and light reflectors and various other items of hardware are enough, to my mind, to prevent the birdie from coming out." ...... Henri Cartier-Bresson- Bottom
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Andrew
One can calculate the combined swept volume of the woofers and make the opening that big, that would be considered 'optimal'. But experience has shown an opening that big isn't necessary
What's the wall stud spacing? If it's 16"OC then a opening 14.5" that fits between the studs would be fine.
I don't know the building codes for folks living in 'metric' countries. Narrower is better, but I wouldn't go much smaller than 14.5" wide
theAudioWorx
Klone-Audio
IB subwoofer FAQ page
"Complicated equipment and light reflectors and various other items of hardware are enough, to my mind, to prevent the birdie from coming out." ...... Henri Cartier-Bresson- Bottom
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Thanks Thomas I believe they're 16" OC so that shouldn't be a problem
I don't know the building codes for folks living in 'metric' countries
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what about the attic?-the studs(truss/joists)up there are usually 24" on center and you could use a 20x20 central heat return grill for the hole(that's how I made mine-I didn't feel like making my own grill-and it looks just like the real A/C return grill in the hall-nobody even notices it)-I only have 2 drivers in mine now but I was carefull to design it so I can add 2 more if I ever go completely insane
otherwise the slot type thing sounds OK too-just a bigger hole(good for performance-bad for SAF)
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"The appreciation of music is subjective.The reproduction of music isn't."-Bill Dudleston=+=+=+=+=+=+=
"The appreciation of music is subjective.The reproduction of music isn't."-Bill Dudleston- Bottom
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My theater is in the basement so a ceiling mount is out of the question.
I purchased the wood from HD tonight and have the box built, glued and clamped right now in the shop. Tomorrow I'll take it outside and route out the driver holes and install the beast in its new home. So far everythings going well but the real test will be tomorrow afternoon when I fire it up
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Well its installed and I've started cleaning up the mess from the building process. What I ended up building is a bos that's 36" long by 19" tall and 14" wide. The top, sides and back are 1.5" thick and the bottom's braced with some 2 by 4's. I also added a brace to the back to the floor joist above it to stop the back from moving around. So far I'm dissapointed in its output since like my first attempt at an IB in the same location the overall output is very underwhelming. My SPL meter is currently on loan but I hope to get it back shortly (tomorrow) so I can do some testing and see just what's going on and maybe play with the BFD settings etc. Right now I have the voice coils wired in // and the drivers in series so I end up with an 8 ohm load per pair. I might try running them with just one voice coil to get down to a 4 ohm load and see how that works but right now I have all the LFE settings set to MAX and other then shaking the walls it doesn't seem to have near as much output as the dual 220L ported tempests I had before.
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hmmm...maybe it's because you're not hearing the distortion you usually get from a box(there's no box to contribute now)? maybe they're not getting enough power?maybe that is just a bad place room wise?
heck I don't know-but I've been to mike knapps house(he has 4 tempest mounted in the wall-simple baffle style)you've probably seen pics of it-and he has about 150 watts per and a very large room and it's very impressive so I know the parts you have are capable-what's the room size-layout
maybe that "punch" you're trying to get is not in the subwoofer range-more like 100hz?
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"The appreciation of music is subjective.The reproduction of music isn't."-Bill Dudleston=+=+=+=+=+=+=
"The appreciation of music is subjective.The reproduction of music isn't."-Bill Dudleston- Bottom
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Robert the room is 12 feet wide by 23 feet deep with a drop ceiling at 6'9". It could be the placement but one of the previous boxxed tempests used to sit about a foot away from the IB's mouth.
I know the amount of power isn't very high at the moment so we'll see what happens when I try them as single voice coils and send 100 watts to each driver.
I've got a couple of interesting back up idea's if this doesn't turn out to work though and so far the investment is only a single sheet of MDF...and time
Of the two other possible idea's I'm considering one is to simply cut another hole in the old box's and mount a second tempest into that box. I'd put the other driver on the back wall and then wire them out of phase to get a dipole type sub. They're 220 liters each so I'd need to stuff them a lot as that's not a large box for two tempests but it would be easy enough to do. I'm going to run some sim's and see what the models have to say about that design.
The other thought was along the lines of Jon's Avro Part dipole alignment with two tempests in a baffle "H" sitting beside my M8a towers. Again these would be simple and quick to build and might still give me some of the benefits of the IB but with more placement options.
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I think I'm going to try to Klone thomas's Rava Too concept only with my Tempest box's and see how that works for me since i can do that with no extra work other then dragging in those heavy sub box's from outside again :cry: I did look at the model for the isoberik config in my 214 liter box and it looks pretty good in winisd (lspcad doesn't seem to have the tempests driver in the free version?)
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it doesn't seem to have near as much output as the dual 220L ported tempests I had before.
I doubt that the amp set up has enough 'grunt' for an IB. Ported boxes are the most efficient designs available.
You also might have some room issues with the IB placement. Did you 'test' the IB location before building it?
I'd put the other driver on the back wall and then wire them out of phase to get a dipole type sub.
think I'm going to try to Klone thomas's Rava Too concept only with my Tempest box's
The other thought was along the lines of Jon's Avro Part dipole alignment with two tempests in a baffle "H" sitting beside my M8a towers. Again these would be simple and quick to build and might still give me some of the benefits of the IB but with more placement options
Also it may be that you just like the sonic signature of ported boxes, certainly nothing wrong with that.
theAudioWorx
Klone-Audio
IB subwoofer FAQ page
"Complicated equipment and light reflectors and various other items of hardware are enough, to my mind, to prevent the birdie from coming out." ...... Henri Cartier-Bresson- Bottom
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The only time that there is an advantage to an isobaric design is when space is extremely limited and one must have a very small box. The output from an isobaric is that of a single driver.
Beg, borrow, buy, or steal, a bigger amp to audition.
The only reason I built my isobaric subs was because I had the cabinets and a stack of Shiva"s lying around.
theAudioWorx
Klone-Audio
IB subwoofer FAQ page
"Complicated equipment and light reflectors and various other items of hardware are enough, to my mind, to prevent the birdie from coming out." ...... Henri Cartier-Bresson- Bottom
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another crazy idea-block the port-put another driver on the box mounted backwards(magnet out) wired out of phase(in phase to the listening area) like an M&K subwoofer-I have one that is still pretty impressive considering what is is(2 x12" drivers push/pull design-not really high excursion by modern standards-and 125 watt plate amp=MX-90)
I wonder what the same design would sound like with 15"ers-they might EQ them though because the box is really not much bigger than is required to house 2 drivers-but it wouldn't be too hard to EQ a sealed box-or even make a LT for it maybe
just a crazy idea-I've always loved the sound from the M&K-but the output leaves a little to be desired
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"The appreciation of music is subjective.The reproduction of music isn't."-Bill Dudleston=+=+=+=+=+=+=
"The appreciation of music is subjective.The reproduction of music isn't."-Bill Dudleston- Bottom
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Ok here's a recap of the events since i last posted...
After thinking about my options I cut another two driver holes in the old 214L box's and plugged the old driver and port holes. I then stuffed them full of poly and fibreglass wired them up and have spent the last couple of hours playing with different placement options.
what I've come to learn is that I'm an idiot :roll: After trying to place them side by side so the drivers were facing each other the output wasn't that great so on a whim I told my helpper (cousin) to reverse the polarity on one sub and voila the house just about came crashing down around us! I then started tracing back the wires and sure enough some duffus (i.e. me) plugged in one of the subs backwards to the rest of the speakers in the room...and its been this way all weekend which of course means that the IB never had a chance if one side was out of phase with the other :?
So its now 9:30 and I've been "subbing" since I got home from work on friday night but damnit I'm going to take a break and eat some food (haven't seen food since 1PM) and then its time to install the drivers back into the IB and see what happens then.
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Andrew, I didn't even want to ask if you confirmed the phase relationship between the two subs and their respective voice coils... I didn't want it to come across the wrong way - nobody likes a critic, but...
I was following your progress via your posts, and when you said that the bass from the IB was "underwhelming", to say the least, I had to bite my ttongue, as I was ready to pick up the phone and ask you about it.
You didn't really cross up the polarities, did you? (it must have been a cold solder joint in the amp somewhere, yeah, that's it, a cold solder joint...)- Bottom
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Yup its a classic case of Occams Razor :LOL: In my defense (weak as it may be) on my HK amp each of the 5 channels all have the positve and negative poles on the same side while my new rotel has the right front and right surrounds backwards to the other three channels..of course the large + and - symbols and the red and black knobs should have given it away :boozer:
I wish you had called though as you'd have saved me a lot of grief. Can I make one small request though? Can I have the humble pie with ice cream?
Now that I have the IB wired properly it definatly has a lot more output. Its also a VERY different sounding bass then the dual sealed tempests and frankly at this point I'm unsure which I like best...esp with all the different configurations we've tried tonight as we moved the subs around the room. I think from a sheer output/punch standpoint having both sealed units facing each other gave us the most bang while the IB most definatly goes much deeper. I do have the BFD to consider as well as its still engaged and set to the presets to the old subs so I'm going to disable that and see what effect that has. I could always add in some boost in the mid bass region on the IB if I felt it was lacking....time to go back and play.
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Yup its a classic case of Occams Razor
As I mentioned before, I don't use a razor, I just pound the stubble back in with the blunt end of an axe and bite it off from the inside. 8O- Bottom
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IB subwoofer FAQ page
"Complicated equipment and light reflectors and various other items of hardware are enough, to my mind, to prevent the birdie from coming out." ...... Henri Cartier-Bresson- Bottom
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Once again through our massive propaganda and marketing campaign, the 'Cult' snags another victim, oops I mean converts another lost soul.
arty:
theAudioWorx
Klone-Audio
IB subwoofer FAQ page
"Complicated equipment and light reflectors and various other items of hardware are enough, to my mind, to prevent the birdie from coming out." ...... Henri Cartier-Bresson- Bottom
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Originally posted by Andrew Prattit was a little overwhelming 8O
say how about some max spl numbers?-just curious
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"The appreciation of music is subjective.The reproduction of music isn't."-Bill Dudleston=+=+=+=+=+=+=
"The appreciation of music is subjective.The reproduction of music isn't."-Bill Dudleston- Bottom
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yeah-hit the max hold button right before the walls crush you.lol
I only have about 300 watts going to 2x15" tc sounds drivers and I get about 113db at 20hz(corrected for the RS meter)-but my room is pretty small(14x14x8) and I'm just wondering how that compares to some other IB setups-I could always put 2 more drivers up there :twisted:
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"The appreciation of music is subjective.The reproduction of music isn't."-Bill Dudleston=+=+=+=+=+=+=
"The appreciation of music is subjective.The reproduction of music isn't."-Bill Dudleston- Bottom
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