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#81
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Adire Tempest Downfiring Ported Subwoofer Project : Polyfill Concerns
On Fri, 26 Dec 2003 15:17:13 +0100, Peter Larsen
wrote: Stewart Pinkerton wrote: Nobody seem to worry about air distortion ... Could you give me a pointer to such a site? It's the idea of a *big* hole in the ceiling that is caused WAF problems. http://t-3.cc/users/audioworx/page13-12Shiva1.html - a subpage of http://www.klone-audio.com/ - 12 large bass units firing into a box with an estimated 12 by 12 inch opening into the listening room. Very impressive! Especially considering the ratio of driver area to throat area. For a more practical implementation of using multiple loudspeakers one should in my opinion think differently. I would arrange a row of loudspeakers on the loft in each side of the room and let the sound enter the room via a long slit near the ceiling/wall junction. It would still be possible to mount the loudspeakers vertically for longevity (playing "downwards-sideways" into the slit) and it could be implemented very discreetly. It will also provide a superiour coupling to the room. A slit is certainly an option in my room, although I might have to write my own modelling program! :-( Peerless has a 10" sub-bass that looks about right if used in multiples. At the moment, a pair of Adire Tempests looks to be the most likely solution. -- Stewart Pinkerton | Music is Art - Audio is Engineering |
#82
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Adire Tempest Downfiring Ported Subwoofer Project : Polyfill Concerns
On Fri, 26 Dec 2003 15:17:13 +0100, Peter Larsen
wrote: Stewart Pinkerton wrote: Nobody seem to worry about air distortion ... Could you give me a pointer to such a site? It's the idea of a *big* hole in the ceiling that is caused WAF problems. http://t-3.cc/users/audioworx/page13-12Shiva1.html - a subpage of http://www.klone-audio.com/ - 12 large bass units firing into a box with an estimated 12 by 12 inch opening into the listening room. Very impressive! Especially considering the ratio of driver area to throat area. For a more practical implementation of using multiple loudspeakers one should in my opinion think differently. I would arrange a row of loudspeakers on the loft in each side of the room and let the sound enter the room via a long slit near the ceiling/wall junction. It would still be possible to mount the loudspeakers vertically for longevity (playing "downwards-sideways" into the slit) and it could be implemented very discreetly. It will also provide a superiour coupling to the room. A slit is certainly an option in my room, although I might have to write my own modelling program! :-( Peerless has a 10" sub-bass that looks about right if used in multiples. At the moment, a pair of Adire Tempests looks to be the most likely solution. -- Stewart Pinkerton | Music is Art - Audio is Engineering |
#83
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Adire Tempest Downfiring Ported Subwoofer Project : Polyfill Concerns
"Stewart Pinkerton" wrote in message ... On Fri, 26 Dec 2003 16:35:18 -0600, "Rusty Boudreaux" wrote: "Stewart Pinkerton" wrote in message ... Thanks Rusty, I did find them after trawling the Stryke site. I've e-mailed them for a quote, as their on-line store implies world-wide shipping, so we'll see what transpires. I must say that they are the coolest *looking* drivers around, with those big alloy cones! I think the Tumults are more impressive but the AV15s are certainly awe inspiring! During the first preorder (over a year ago) the drivers came with a logo on the cone by default. You may have to specify no logo. Stryke is essentially a one man shop (John E. Janowitz). I think his wife just had a baby so he may be somewhat tied up. His phone is 920-469-9198 if all else fails. There's also a Stryke web forum. http://forum.stryke.com/ Thanks for that, Rusty. I must say, the recent discussions on the Stryke forum are *not* encouraging to a potential purchaser! I appreciate the problems if he's a 'one man band' and a new dad, but at the end of the day I'll need products, not promises............ -- Stewart Pinkerton | Music is Art - Audio is Engineering Keep us informed on the project and it's results. I'm planning a project with a single Shiva in a ported box of either 3.6 or 4.8 cu ft. f3 predictions are 25 and 21 Hz, respectively. Leaning towards the smaller box for WAF nad with room gain it should get to at least 20 Hz in the room it will be used in. |
#84
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Adire Tempest Downfiring Ported Subwoofer Project : Polyfill Concerns
"Stewart Pinkerton" wrote in message ... On Fri, 26 Dec 2003 16:35:18 -0600, "Rusty Boudreaux" wrote: "Stewart Pinkerton" wrote in message ... Thanks Rusty, I did find them after trawling the Stryke site. I've e-mailed them for a quote, as their on-line store implies world-wide shipping, so we'll see what transpires. I must say that they are the coolest *looking* drivers around, with those big alloy cones! I think the Tumults are more impressive but the AV15s are certainly awe inspiring! During the first preorder (over a year ago) the drivers came with a logo on the cone by default. You may have to specify no logo. Stryke is essentially a one man shop (John E. Janowitz). I think his wife just had a baby so he may be somewhat tied up. His phone is 920-469-9198 if all else fails. There's also a Stryke web forum. http://forum.stryke.com/ Thanks for that, Rusty. I must say, the recent discussions on the Stryke forum are *not* encouraging to a potential purchaser! I appreciate the problems if he's a 'one man band' and a new dad, but at the end of the day I'll need products, not promises............ -- Stewart Pinkerton | Music is Art - Audio is Engineering Keep us informed on the project and it's results. I'm planning a project with a single Shiva in a ported box of either 3.6 or 4.8 cu ft. f3 predictions are 25 and 21 Hz, respectively. Leaning towards the smaller box for WAF nad with room gain it should get to at least 20 Hz in the room it will be used in. |
#85
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Adire Tempest Downfiring Ported Subwoofer Project : Polyfill Concerns
"Stewart Pinkerton" wrote in message ... On Fri, 26 Dec 2003 16:35:18 -0600, "Rusty Boudreaux" wrote: "Stewart Pinkerton" wrote in message ... Thanks Rusty, I did find them after trawling the Stryke site. I've e-mailed them for a quote, as their on-line store implies world-wide shipping, so we'll see what transpires. I must say that they are the coolest *looking* drivers around, with those big alloy cones! I think the Tumults are more impressive but the AV15s are certainly awe inspiring! During the first preorder (over a year ago) the drivers came with a logo on the cone by default. You may have to specify no logo. Stryke is essentially a one man shop (John E. Janowitz). I think his wife just had a baby so he may be somewhat tied up. His phone is 920-469-9198 if all else fails. There's also a Stryke web forum. http://forum.stryke.com/ Thanks for that, Rusty. I must say, the recent discussions on the Stryke forum are *not* encouraging to a potential purchaser! I appreciate the problems if he's a 'one man band' and a new dad, but at the end of the day I'll need products, not promises............ -- Stewart Pinkerton | Music is Art - Audio is Engineering Keep us informed on the project and it's results. I'm planning a project with a single Shiva in a ported box of either 3.6 or 4.8 cu ft. f3 predictions are 25 and 21 Hz, respectively. Leaning towards the smaller box for WAF nad with room gain it should get to at least 20 Hz in the room it will be used in. |
#86
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Adire Tempest Downfiring Ported Subwoofer Project : Polyfill Concerns
"Stewart Pinkerton" wrote in message
... I appreciate the problems if he's a 'one man band' and a new dad, but at the end of the day I'll need products, not promises............ I've been absent from the forum for awhile. It does seem like John's backed up right now but trying to work out the backlog. Apparently Stryke will be changing it's name Jan 1st due to trademark issues. Looks like Acoustic Elegance is the leading candidate. FYI, I ordered my AV15s during the first preorder back in Oct '02. I believe John ordered 500 AV15s from TC Sounds with the intent to have several hundred left over to keep in stock. TC Sounds messed up the voice coils (single 4 ohm instead of dual 2 ohm) which delayed shipments until Jan '03. By the time they shipped John had sold out of all the drivers! Since then Kyle at www.acoustic-visions.com has been keeping drivers in stock but they're currently out due to waiting on the new design (dual spider) but Kyle won't ship outside USA. If you can handle the wait and get the UK shipping worked out the AV15 are certainly worth it. If not, go for the Tempest. A 3x2 array of Tempests will be as good as four AV15s or three Tumults I previously had a Velodyne F1800R and thought it was king. The IB wipes the floor with it in every way...including cost. I had planned on performing a level matched DBT but there was no need. The F1800 now sits behind the computer. |
#87
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Adire Tempest Downfiring Ported Subwoofer Project : Polyfill Concerns
"Stewart Pinkerton" wrote in message
... I appreciate the problems if he's a 'one man band' and a new dad, but at the end of the day I'll need products, not promises............ I've been absent from the forum for awhile. It does seem like John's backed up right now but trying to work out the backlog. Apparently Stryke will be changing it's name Jan 1st due to trademark issues. Looks like Acoustic Elegance is the leading candidate. FYI, I ordered my AV15s during the first preorder back in Oct '02. I believe John ordered 500 AV15s from TC Sounds with the intent to have several hundred left over to keep in stock. TC Sounds messed up the voice coils (single 4 ohm instead of dual 2 ohm) which delayed shipments until Jan '03. By the time they shipped John had sold out of all the drivers! Since then Kyle at www.acoustic-visions.com has been keeping drivers in stock but they're currently out due to waiting on the new design (dual spider) but Kyle won't ship outside USA. If you can handle the wait and get the UK shipping worked out the AV15 are certainly worth it. If not, go for the Tempest. A 3x2 array of Tempests will be as good as four AV15s or three Tumults I previously had a Velodyne F1800R and thought it was king. The IB wipes the floor with it in every way...including cost. I had planned on performing a level matched DBT but there was no need. The F1800 now sits behind the computer. |
#88
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Adire Tempest Downfiring Ported Subwoofer Project : Polyfill Concerns
"Stewart Pinkerton" wrote in message
... I appreciate the problems if he's a 'one man band' and a new dad, but at the end of the day I'll need products, not promises............ I've been absent from the forum for awhile. It does seem like John's backed up right now but trying to work out the backlog. Apparently Stryke will be changing it's name Jan 1st due to trademark issues. Looks like Acoustic Elegance is the leading candidate. FYI, I ordered my AV15s during the first preorder back in Oct '02. I believe John ordered 500 AV15s from TC Sounds with the intent to have several hundred left over to keep in stock. TC Sounds messed up the voice coils (single 4 ohm instead of dual 2 ohm) which delayed shipments until Jan '03. By the time they shipped John had sold out of all the drivers! Since then Kyle at www.acoustic-visions.com has been keeping drivers in stock but they're currently out due to waiting on the new design (dual spider) but Kyle won't ship outside USA. If you can handle the wait and get the UK shipping worked out the AV15 are certainly worth it. If not, go for the Tempest. A 3x2 array of Tempests will be as good as four AV15s or three Tumults I previously had a Velodyne F1800R and thought it was king. The IB wipes the floor with it in every way...including cost. I had planned on performing a level matched DBT but there was no need. The F1800 now sits behind the computer. |
#89
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Adire Manifolding, was " Adire Tempest Downfiring Ported Subwoofer
Stewart Pinkerton wrote:
A slit is certainly an option in my room, although I might have to write my own modelling program! :-( Model, why? - ah well, one item of horn modelling software does exist "out there", I have it somewhere on some harddisk. Peerless has a 10" sub-bass that looks about right if used in multiples. If I wanted to feed an elongated opening, then doing it with a line of units comes to mind. At the moment, a pair of Adire Tempests looks to be the most likely solution. Freehand a manifold, i. e. a conical horn (x), as the adapter between the unit and the slit. Conical horns are wonderfully simple: the faster they expand the higher their range. They also have the advantage of low distortion due to the fast initial expansion. Remember however to also load the other side of the membrane, at a wild guess and without checking anything a 5 cubic feet box comes to mind, possibly 7, this to minimize equal order distortion and to provide some driver protection. No warranty of any kind, suggested only for those who can freehand the amount of garlic and curry ..... Stewart Pinkerton | Music is Art - Audio is Engineering (x) From the unit you make a transition to the slit width, 3" comes to mind, and then you let the horn expand in one plane only horisontally on the floor of the loft and then make a 90 degree down turn into the slit. It is very easy to brace such a flat structure with dividers to ensure that it is suitably rigid. The slit area should not be smaller than the cone area, for a "seat of the pants" design guide I'd aim for two to three times the cone area and use a fairly rapid expansion of the conical "hornifold". Kind regards Peter Larsen -- ************************************************** ************* * \\\\\\\ Quality Ascii handcrafted by Peter Larsen /////// * * \\\\\\\ My site is at: http://www.muyiovatki.dk /////// * ************************************************** ******* |
#90
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Adire Manifolding, was " Adire Tempest Downfiring Ported Subwoofer
Stewart Pinkerton wrote:
A slit is certainly an option in my room, although I might have to write my own modelling program! :-( Model, why? - ah well, one item of horn modelling software does exist "out there", I have it somewhere on some harddisk. Peerless has a 10" sub-bass that looks about right if used in multiples. If I wanted to feed an elongated opening, then doing it with a line of units comes to mind. At the moment, a pair of Adire Tempests looks to be the most likely solution. Freehand a manifold, i. e. a conical horn (x), as the adapter between the unit and the slit. Conical horns are wonderfully simple: the faster they expand the higher their range. They also have the advantage of low distortion due to the fast initial expansion. Remember however to also load the other side of the membrane, at a wild guess and without checking anything a 5 cubic feet box comes to mind, possibly 7, this to minimize equal order distortion and to provide some driver protection. No warranty of any kind, suggested only for those who can freehand the amount of garlic and curry ..... Stewart Pinkerton | Music is Art - Audio is Engineering (x) From the unit you make a transition to the slit width, 3" comes to mind, and then you let the horn expand in one plane only horisontally on the floor of the loft and then make a 90 degree down turn into the slit. It is very easy to brace such a flat structure with dividers to ensure that it is suitably rigid. The slit area should not be smaller than the cone area, for a "seat of the pants" design guide I'd aim for two to three times the cone area and use a fairly rapid expansion of the conical "hornifold". Kind regards Peter Larsen -- ************************************************** ************* * \\\\\\\ Quality Ascii handcrafted by Peter Larsen /////// * * \\\\\\\ My site is at: http://www.muyiovatki.dk /////// * ************************************************** ******* |
#91
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Adire Manifolding, was " Adire Tempest Downfiring Ported Subwoofer
Stewart Pinkerton wrote:
A slit is certainly an option in my room, although I might have to write my own modelling program! :-( Model, why? - ah well, one item of horn modelling software does exist "out there", I have it somewhere on some harddisk. Peerless has a 10" sub-bass that looks about right if used in multiples. If I wanted to feed an elongated opening, then doing it with a line of units comes to mind. At the moment, a pair of Adire Tempests looks to be the most likely solution. Freehand a manifold, i. e. a conical horn (x), as the adapter between the unit and the slit. Conical horns are wonderfully simple: the faster they expand the higher their range. They also have the advantage of low distortion due to the fast initial expansion. Remember however to also load the other side of the membrane, at a wild guess and without checking anything a 5 cubic feet box comes to mind, possibly 7, this to minimize equal order distortion and to provide some driver protection. No warranty of any kind, suggested only for those who can freehand the amount of garlic and curry ..... Stewart Pinkerton | Music is Art - Audio is Engineering (x) From the unit you make a transition to the slit width, 3" comes to mind, and then you let the horn expand in one plane only horisontally on the floor of the loft and then make a 90 degree down turn into the slit. It is very easy to brace such a flat structure with dividers to ensure that it is suitably rigid. The slit area should not be smaller than the cone area, for a "seat of the pants" design guide I'd aim for two to three times the cone area and use a fairly rapid expansion of the conical "hornifold". Kind regards Peter Larsen -- ************************************************** ************* * \\\\\\\ Quality Ascii handcrafted by Peter Larsen /////// * * \\\\\\\ My site is at: http://www.muyiovatki.dk /////// * ************************************************** ******* |
#92
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Adire Manifolding, was " Adire Tempest Downfiring Ported Subwoofer Project : Polyfill Concerns"
On Sat, 27 Dec 2003 11:23:09 +0100, Peter Larsen
wrote: Stewart Pinkerton wrote: A slit is certainly an option in my room, although I might have to write my own modelling program! :-( Model, why? - ah well, one item of horn modelling software does exist "out there", I have it somewhere on some harddisk. Peerless has a 10" sub-bass that looks about right if used in multiples. If I wanted to feed an elongated opening, then doing it with a line of units comes to mind. I'm looking at the subwoofer bottom line of Euros per litre! :-) A dozen Peerless units doesn't cost out so well as a couple of Tempests, or especially Stryke AV15s. At the moment, a pair of Adire Tempests looks to be the most likely solution. Freehand a manifold, i. e. a conical horn (x), as the adapter between the unit and the slit. Conical horns are wonderfully simple: the faster they expand the higher their range. They also have the advantage of low distortion due to the fast initial expansion. This doesn't make sense to me, as there is no horn expansion if the slit is the same area as the driver Sd, as you suggest below. Remember however to also load the other side of the membrane, at a wild guess and without checking anything a 5 cubic feet box comes to mind, possibly 7, this to minimize equal order distortion and to provide some driver protection. Yes, this is one of my concerns. No warranty of any kind, suggested only for those who can freehand the amount of garlic and curry ..... Always! Tonight of course, it'll be turkey curry........... :-) (x) From the unit you make a transition to the slit width, 3" comes to mind, and then you let the horn expand in one plane only horisontally on the floor of the loft and then make a 90 degree down turn into the slit. It is very easy to brace such a flat structure with dividers to ensure that it is suitably rigid. The slit area should not be smaller than the cone area, for a "seat of the pants" design guide I'd aim for two to three times the cone area and use a fairly rapid expansion of the conical "hornifold". I'm still looking at a manifold exit area of 0.3-0.5 the Sd of the two drivers (for improved WAF....) , expanding into the 1/8 space of the room corner. As you say, there may need to be a back box to equalise cone loading. OTOH, since I'm staying well below Xmax for normal operation, perhaps this is all a little paranoid! OTGH, design time costs me nothing, so why not do it right first time.................. -- Stewart Pinkerton | Music is Art - Audio is Engineering |
#93
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Adire Manifolding, was " Adire Tempest Downfiring Ported Subwoofer Project : Polyfill Concerns"
On Sat, 27 Dec 2003 11:23:09 +0100, Peter Larsen
wrote: Stewart Pinkerton wrote: A slit is certainly an option in my room, although I might have to write my own modelling program! :-( Model, why? - ah well, one item of horn modelling software does exist "out there", I have it somewhere on some harddisk. Peerless has a 10" sub-bass that looks about right if used in multiples. If I wanted to feed an elongated opening, then doing it with a line of units comes to mind. I'm looking at the subwoofer bottom line of Euros per litre! :-) A dozen Peerless units doesn't cost out so well as a couple of Tempests, or especially Stryke AV15s. At the moment, a pair of Adire Tempests looks to be the most likely solution. Freehand a manifold, i. e. a conical horn (x), as the adapter between the unit and the slit. Conical horns are wonderfully simple: the faster they expand the higher their range. They also have the advantage of low distortion due to the fast initial expansion. This doesn't make sense to me, as there is no horn expansion if the slit is the same area as the driver Sd, as you suggest below. Remember however to also load the other side of the membrane, at a wild guess and without checking anything a 5 cubic feet box comes to mind, possibly 7, this to minimize equal order distortion and to provide some driver protection. Yes, this is one of my concerns. No warranty of any kind, suggested only for those who can freehand the amount of garlic and curry ..... Always! Tonight of course, it'll be turkey curry........... :-) (x) From the unit you make a transition to the slit width, 3" comes to mind, and then you let the horn expand in one plane only horisontally on the floor of the loft and then make a 90 degree down turn into the slit. It is very easy to brace such a flat structure with dividers to ensure that it is suitably rigid. The slit area should not be smaller than the cone area, for a "seat of the pants" design guide I'd aim for two to three times the cone area and use a fairly rapid expansion of the conical "hornifold". I'm still looking at a manifold exit area of 0.3-0.5 the Sd of the two drivers (for improved WAF....) , expanding into the 1/8 space of the room corner. As you say, there may need to be a back box to equalise cone loading. OTOH, since I'm staying well below Xmax for normal operation, perhaps this is all a little paranoid! OTGH, design time costs me nothing, so why not do it right first time.................. -- Stewart Pinkerton | Music is Art - Audio is Engineering |
#94
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Adire Manifolding, was " Adire Tempest Downfiring Ported Subwoofer Project : Polyfill Concerns"
On Sat, 27 Dec 2003 11:23:09 +0100, Peter Larsen
wrote: Stewart Pinkerton wrote: A slit is certainly an option in my room, although I might have to write my own modelling program! :-( Model, why? - ah well, one item of horn modelling software does exist "out there", I have it somewhere on some harddisk. Peerless has a 10" sub-bass that looks about right if used in multiples. If I wanted to feed an elongated opening, then doing it with a line of units comes to mind. I'm looking at the subwoofer bottom line of Euros per litre! :-) A dozen Peerless units doesn't cost out so well as a couple of Tempests, or especially Stryke AV15s. At the moment, a pair of Adire Tempests looks to be the most likely solution. Freehand a manifold, i. e. a conical horn (x), as the adapter between the unit and the slit. Conical horns are wonderfully simple: the faster they expand the higher their range. They also have the advantage of low distortion due to the fast initial expansion. This doesn't make sense to me, as there is no horn expansion if the slit is the same area as the driver Sd, as you suggest below. Remember however to also load the other side of the membrane, at a wild guess and without checking anything a 5 cubic feet box comes to mind, possibly 7, this to minimize equal order distortion and to provide some driver protection. Yes, this is one of my concerns. No warranty of any kind, suggested only for those who can freehand the amount of garlic and curry ..... Always! Tonight of course, it'll be turkey curry........... :-) (x) From the unit you make a transition to the slit width, 3" comes to mind, and then you let the horn expand in one plane only horisontally on the floor of the loft and then make a 90 degree down turn into the slit. It is very easy to brace such a flat structure with dividers to ensure that it is suitably rigid. The slit area should not be smaller than the cone area, for a "seat of the pants" design guide I'd aim for two to three times the cone area and use a fairly rapid expansion of the conical "hornifold". I'm still looking at a manifold exit area of 0.3-0.5 the Sd of the two drivers (for improved WAF....) , expanding into the 1/8 space of the room corner. As you say, there may need to be a back box to equalise cone loading. OTOH, since I'm staying well below Xmax for normal operation, perhaps this is all a little paranoid! OTGH, design time costs me nothing, so why not do it right first time.................. -- Stewart Pinkerton | Music is Art - Audio is Engineering |
#95
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Adire Manifolding, was " Adire Tempest Downfiring Ported
Stewart Pinkerton wrote:
Freehand a manifold, i. e. a conical horn (x), as the adapter between the unit and the slit. Conical horns are wonderfully simple: the faster they expand the higher their range. They also have the advantage of low distortion due to the fast initial expansion. This doesn't make sense to me, as there is no horn expansion if the slit is the same area as the driver Sd, as you suggest below. Expansion prevents too many parallel walls. If you go for the suggested model with 3" as the smallest dimension of manifold and slit then you have to make some kind of a transition from the 13" membrane. This is not about midrange, so doing it the crude way comes to mind, i. e. starting the manifold with a - tja da dum - 3 by 13 inches or 3 by 10 inches initial area. Even to simply enter the room with the membrane area will then require expansion. I'm still looking at a manifold exit area of 0.3-0.5 the Sd of the two drivers (for improved WAF....) , expanding into the 1/8 space of the room corner. As you say, there may need to be a back box to equalise cone loading. Ah, going to the room corner is a mitigating factor because it allows you to use the corner as an extension of the conical horn in the manifold. And with an "L" shaped slit in the ceiling in the corner it ought to be possible to make it a lot more compact than I had first thougth. OTOH, since I'm staying well below Xmax for normal operation, perhaps this is all a little paranoid! OTGH, design time costs me nothing, so why not do it right first time.................. Minimizing distortion and getting an optimum coupling to the room are worthwhile aims and probably pre-requites for a system that is supposed to be able to play well in trippel forte as well as in the way more difficult trippel piano. Try searching for hornresp ... it may be possible to express this as a conical horn it can understand, in which case it could be helpful to try modelling in it. Stewart Pinkerton | Music is Art - Audio is Engineering Kind regards Peter Larsen -- ************************************************** ************* * \\\\\\\ Quality Ascii handcrafted by Peter Larsen /////// * * \\\\\\\ My site is at: http://www.muyiovatki.dk /////// * ************************************************** ******* |
#96
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Adire Manifolding, was " Adire Tempest Downfiring Ported
Stewart Pinkerton wrote:
Freehand a manifold, i. e. a conical horn (x), as the adapter between the unit and the slit. Conical horns are wonderfully simple: the faster they expand the higher their range. They also have the advantage of low distortion due to the fast initial expansion. This doesn't make sense to me, as there is no horn expansion if the slit is the same area as the driver Sd, as you suggest below. Expansion prevents too many parallel walls. If you go for the suggested model with 3" as the smallest dimension of manifold and slit then you have to make some kind of a transition from the 13" membrane. This is not about midrange, so doing it the crude way comes to mind, i. e. starting the manifold with a - tja da dum - 3 by 13 inches or 3 by 10 inches initial area. Even to simply enter the room with the membrane area will then require expansion. I'm still looking at a manifold exit area of 0.3-0.5 the Sd of the two drivers (for improved WAF....) , expanding into the 1/8 space of the room corner. As you say, there may need to be a back box to equalise cone loading. Ah, going to the room corner is a mitigating factor because it allows you to use the corner as an extension of the conical horn in the manifold. And with an "L" shaped slit in the ceiling in the corner it ought to be possible to make it a lot more compact than I had first thougth. OTOH, since I'm staying well below Xmax for normal operation, perhaps this is all a little paranoid! OTGH, design time costs me nothing, so why not do it right first time.................. Minimizing distortion and getting an optimum coupling to the room are worthwhile aims and probably pre-requites for a system that is supposed to be able to play well in trippel forte as well as in the way more difficult trippel piano. Try searching for hornresp ... it may be possible to express this as a conical horn it can understand, in which case it could be helpful to try modelling in it. Stewart Pinkerton | Music is Art - Audio is Engineering Kind regards Peter Larsen -- ************************************************** ************* * \\\\\\\ Quality Ascii handcrafted by Peter Larsen /////// * * \\\\\\\ My site is at: http://www.muyiovatki.dk /////// * ************************************************** ******* |
#97
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Adire Manifolding, was " Adire Tempest Downfiring Ported
Stewart Pinkerton wrote:
Freehand a manifold, i. e. a conical horn (x), as the adapter between the unit and the slit. Conical horns are wonderfully simple: the faster they expand the higher their range. They also have the advantage of low distortion due to the fast initial expansion. This doesn't make sense to me, as there is no horn expansion if the slit is the same area as the driver Sd, as you suggest below. Expansion prevents too many parallel walls. If you go for the suggested model with 3" as the smallest dimension of manifold and slit then you have to make some kind of a transition from the 13" membrane. This is not about midrange, so doing it the crude way comes to mind, i. e. starting the manifold with a - tja da dum - 3 by 13 inches or 3 by 10 inches initial area. Even to simply enter the room with the membrane area will then require expansion. I'm still looking at a manifold exit area of 0.3-0.5 the Sd of the two drivers (for improved WAF....) , expanding into the 1/8 space of the room corner. As you say, there may need to be a back box to equalise cone loading. Ah, going to the room corner is a mitigating factor because it allows you to use the corner as an extension of the conical horn in the manifold. And with an "L" shaped slit in the ceiling in the corner it ought to be possible to make it a lot more compact than I had first thougth. OTOH, since I'm staying well below Xmax for normal operation, perhaps this is all a little paranoid! OTGH, design time costs me nothing, so why not do it right first time.................. Minimizing distortion and getting an optimum coupling to the room are worthwhile aims and probably pre-requites for a system that is supposed to be able to play well in trippel forte as well as in the way more difficult trippel piano. Try searching for hornresp ... it may be possible to express this as a conical horn it can understand, in which case it could be helpful to try modelling in it. Stewart Pinkerton | Music is Art - Audio is Engineering Kind regards Peter Larsen -- ************************************************** ************* * \\\\\\\ Quality Ascii handcrafted by Peter Larsen /////// * * \\\\\\\ My site is at: http://www.muyiovatki.dk /////// * ************************************************** ******* |
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Adire Manifolding, was " Adire Tempest Downfiring Ported Subwoofer Project : Polyfill Concerns"
"Stewart Pinkerton" wrote in message
... OTOH, since I'm staying well below Xmax for normal operation, perhaps this is all a little paranoid! OTGH, design time costs me nothing, so why not do it right first time.................. If your house is drywall/sheetrock just go for it. Cheap and easy to patch Also, if you didn't see there's a set a photos on the first gallery page of the IB site where someone built a cloth covered grill for a white ceiling. I would have made it flush with the ceiling...maybe something else to think about for wife acceptance. |
#99
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Adire Manifolding, was " Adire Tempest Downfiring Ported Subwoofer Project : Polyfill Concerns"
"Stewart Pinkerton" wrote in message
... OTOH, since I'm staying well below Xmax for normal operation, perhaps this is all a little paranoid! OTGH, design time costs me nothing, so why not do it right first time.................. If your house is drywall/sheetrock just go for it. Cheap and easy to patch Also, if you didn't see there's a set a photos on the first gallery page of the IB site where someone built a cloth covered grill for a white ceiling. I would have made it flush with the ceiling...maybe something else to think about for wife acceptance. |
#100
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Adire Manifolding, was " Adire Tempest Downfiring Ported Subwoofer Project : Polyfill Concerns"
"Stewart Pinkerton" wrote in message
... OTOH, since I'm staying well below Xmax for normal operation, perhaps this is all a little paranoid! OTGH, design time costs me nothing, so why not do it right first time.................. If your house is drywall/sheetrock just go for it. Cheap and easy to patch Also, if you didn't see there's a set a photos on the first gallery page of the IB site where someone built a cloth covered grill for a white ceiling. I would have made it flush with the ceiling...maybe something else to think about for wife acceptance. |
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Adire Manifolding, was " Adire Tempest Downfiring Ported
Rusty Boudreaux wrote:
If your house is drywall/sheetrock just go for it. Cheap and easy to patch The nice thing about the slit is that one can install lights in it and a bit of screen in front of it and pretend that it is mood lights for the room. -- ************************************************** ************* * \\\\\\\ Quality Ascii handcrafted by Peter Larsen /////// * * \\\\\\\ My site is at: http://www.muyiovatki.dk /////// * ************************************************** ******* |
#102
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Adire Manifolding, was " Adire Tempest Downfiring Ported
Rusty Boudreaux wrote:
If your house is drywall/sheetrock just go for it. Cheap and easy to patch The nice thing about the slit is that one can install lights in it and a bit of screen in front of it and pretend that it is mood lights for the room. -- ************************************************** ************* * \\\\\\\ Quality Ascii handcrafted by Peter Larsen /////// * * \\\\\\\ My site is at: http://www.muyiovatki.dk /////// * ************************************************** ******* |
#103
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Adire Manifolding, was " Adire Tempest Downfiring Ported
Rusty Boudreaux wrote:
If your house is drywall/sheetrock just go for it. Cheap and easy to patch The nice thing about the slit is that one can install lights in it and a bit of screen in front of it and pretend that it is mood lights for the room. -- ************************************************** ************* * \\\\\\\ Quality Ascii handcrafted by Peter Larsen /////// * * \\\\\\\ My site is at: http://www.muyiovatki.dk /////// * ************************************************** ******* |
#104
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Adire Manifolding, was " Adire Tempest Downfiring Ported Subwoofer Project : Polyfill Concerns"
On Sat, 27 Dec 2003 22:18:15 -0600, "Rusty Boudreaux"
wrote: "Stewart Pinkerton" wrote in message ... OTOH, since I'm staying well below Xmax for normal operation, perhaps this is all a little paranoid! OTGH, design time costs me nothing, so why not do it right first time.................. If your house is drywall/sheetrock just go for it. Cheap and easy to patch Nope, it has 13" thick brick/block walls, only the ceiling is conventional wooden joists and plasterboard (sheetrock to you). Also, if you didn't see there's a set a photos on the first gallery page of the IB site where someone built a cloth covered grill for a white ceiling. I would have made it flush with the ceiling...maybe something else to think about for wife acceptance. Yes, I've seen that shot, and I might get away with something similar to that, or two or three of the HVAC vents someone else used. My concern with the cloth approach is that a Vd of 5 litres at 20-50Hz is likely to cause some pretty visible flapping! -- Stewart Pinkerton | Music is Art - Audio is Engineering |
#105
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Adire Manifolding, was " Adire Tempest Downfiring Ported Subwoofer Project : Polyfill Concerns"
On Sat, 27 Dec 2003 22:18:15 -0600, "Rusty Boudreaux"
wrote: "Stewart Pinkerton" wrote in message ... OTOH, since I'm staying well below Xmax for normal operation, perhaps this is all a little paranoid! OTGH, design time costs me nothing, so why not do it right first time.................. If your house is drywall/sheetrock just go for it. Cheap and easy to patch Nope, it has 13" thick brick/block walls, only the ceiling is conventional wooden joists and plasterboard (sheetrock to you). Also, if you didn't see there's a set a photos on the first gallery page of the IB site where someone built a cloth covered grill for a white ceiling. I would have made it flush with the ceiling...maybe something else to think about for wife acceptance. Yes, I've seen that shot, and I might get away with something similar to that, or two or three of the HVAC vents someone else used. My concern with the cloth approach is that a Vd of 5 litres at 20-50Hz is likely to cause some pretty visible flapping! -- Stewart Pinkerton | Music is Art - Audio is Engineering |
#106
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Adire Manifolding, was " Adire Tempest Downfiring Ported Subwoofer Project : Polyfill Concerns"
On Sat, 27 Dec 2003 22:18:15 -0600, "Rusty Boudreaux"
wrote: "Stewart Pinkerton" wrote in message ... OTOH, since I'm staying well below Xmax for normal operation, perhaps this is all a little paranoid! OTGH, design time costs me nothing, so why not do it right first time.................. If your house is drywall/sheetrock just go for it. Cheap and easy to patch Nope, it has 13" thick brick/block walls, only the ceiling is conventional wooden joists and plasterboard (sheetrock to you). Also, if you didn't see there's a set a photos on the first gallery page of the IB site where someone built a cloth covered grill for a white ceiling. I would have made it flush with the ceiling...maybe something else to think about for wife acceptance. Yes, I've seen that shot, and I might get away with something similar to that, or two or three of the HVAC vents someone else used. My concern with the cloth approach is that a Vd of 5 litres at 20-50Hz is likely to cause some pretty visible flapping! -- Stewart Pinkerton | Music is Art - Audio is Engineering |
#107
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Adire Manifolding, was " Adire Tempest Downfiring Ported Subwoofer Project : Polyfill Concerns"
On Sat, 27 Dec 2003 19:03:59 +0100, Peter Larsen
wrote: Stewart Pinkerton wrote: Freehand a manifold, i. e. a conical horn (x), as the adapter between the unit and the slit. Conical horns are wonderfully simple: the faster they expand the higher their range. They also have the advantage of low distortion due to the fast initial expansion. This doesn't make sense to me, as there is no horn expansion if the slit is the same area as the driver Sd, as you suggest below. Expansion prevents too many parallel walls. Which are completely irrelevant in a sub. In fact, a cube is the *best* enclosure shape for a sealed-box sub, as it has maxium wall rigidity for any given volume and material. If you go for the suggested model with 3" as the smallest dimension of manifold and slit then you have to make some kind of a transition from the 13" membrane. This is not about midrange, so doing it the crude way comes to mind, i. e. starting the manifold with a - tja da dum - 3 by 13 inches or 3 by 10 inches initial area. Even to simply enter the room with the membrane area will then require expansion. You can however transit directly from a 13" circle to a 3" x 44" slit (to maintain equal areas) without any expansion whatever, simply by making a double-tapered box, so why bother with an intermediate constriction? BTW, such a manifold box will have minimal resonance problems due to the heavy taper of the box sides, so it's also a mechanically sound design not requiring heroic wall thickness. I'm still looking at a manifold exit area of 0.3-0.5 the Sd of the two drivers (for improved WAF....) , expanding into the 1/8 space of the room corner. As you say, there may need to be a back box to equalise cone loading. Ah, going to the room corner is a mitigating factor because it allows you to use the corner as an extension of the conical horn in the manifold. And with an "L" shaped slit in the ceiling in the corner it ought to be possible to make it a lot more compact than I had first thougth. I currently favour a 10" square aperture, which is reasonably discreet and gives a 3:1 area compression from a pair of 15" drivers. Might have to be a foot square to allow for grille solidity. OTOH, since I'm staying well below Xmax for normal operation, perhaps this is all a little paranoid! OTGH, design time costs me nothing, so why not do it right first time.................. Minimizing distortion and getting an optimum coupling to the room are worthwhile aims and probably pre-requites for a system that is supposed to be able to play well in trippel forte as well as in the way more difficult trippel piano. Indeed so, hence lots of thinking before firing up the jigsaw! Try searching for hornresp ... it may be possible to express this as a conical horn it can understand, in which case it could be helpful to try modelling in it. Aside from the basic expansion into 1/8 space given by corner mounting, I have no intention of getting into the multitudinous problems of horns! -- Stewart Pinkerton | Music is Art - Audio is Engineering |
#108
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Adire Manifolding, was " Adire Tempest Downfiring Ported Subwoofer Project : Polyfill Concerns"
On Sat, 27 Dec 2003 19:03:59 +0100, Peter Larsen
wrote: Stewart Pinkerton wrote: Freehand a manifold, i. e. a conical horn (x), as the adapter between the unit and the slit. Conical horns are wonderfully simple: the faster they expand the higher their range. They also have the advantage of low distortion due to the fast initial expansion. This doesn't make sense to me, as there is no horn expansion if the slit is the same area as the driver Sd, as you suggest below. Expansion prevents too many parallel walls. Which are completely irrelevant in a sub. In fact, a cube is the *best* enclosure shape for a sealed-box sub, as it has maxium wall rigidity for any given volume and material. If you go for the suggested model with 3" as the smallest dimension of manifold and slit then you have to make some kind of a transition from the 13" membrane. This is not about midrange, so doing it the crude way comes to mind, i. e. starting the manifold with a - tja da dum - 3 by 13 inches or 3 by 10 inches initial area. Even to simply enter the room with the membrane area will then require expansion. You can however transit directly from a 13" circle to a 3" x 44" slit (to maintain equal areas) without any expansion whatever, simply by making a double-tapered box, so why bother with an intermediate constriction? BTW, such a manifold box will have minimal resonance problems due to the heavy taper of the box sides, so it's also a mechanically sound design not requiring heroic wall thickness. I'm still looking at a manifold exit area of 0.3-0.5 the Sd of the two drivers (for improved WAF....) , expanding into the 1/8 space of the room corner. As you say, there may need to be a back box to equalise cone loading. Ah, going to the room corner is a mitigating factor because it allows you to use the corner as an extension of the conical horn in the manifold. And with an "L" shaped slit in the ceiling in the corner it ought to be possible to make it a lot more compact than I had first thougth. I currently favour a 10" square aperture, which is reasonably discreet and gives a 3:1 area compression from a pair of 15" drivers. Might have to be a foot square to allow for grille solidity. OTOH, since I'm staying well below Xmax for normal operation, perhaps this is all a little paranoid! OTGH, design time costs me nothing, so why not do it right first time.................. Minimizing distortion and getting an optimum coupling to the room are worthwhile aims and probably pre-requites for a system that is supposed to be able to play well in trippel forte as well as in the way more difficult trippel piano. Indeed so, hence lots of thinking before firing up the jigsaw! Try searching for hornresp ... it may be possible to express this as a conical horn it can understand, in which case it could be helpful to try modelling in it. Aside from the basic expansion into 1/8 space given by corner mounting, I have no intention of getting into the multitudinous problems of horns! -- Stewart Pinkerton | Music is Art - Audio is Engineering |
#109
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Adire Manifolding, was " Adire Tempest Downfiring Ported Subwoofer Project : Polyfill Concerns"
On Sat, 27 Dec 2003 19:03:59 +0100, Peter Larsen
wrote: Stewart Pinkerton wrote: Freehand a manifold, i. e. a conical horn (x), as the adapter between the unit and the slit. Conical horns are wonderfully simple: the faster they expand the higher their range. They also have the advantage of low distortion due to the fast initial expansion. This doesn't make sense to me, as there is no horn expansion if the slit is the same area as the driver Sd, as you suggest below. Expansion prevents too many parallel walls. Which are completely irrelevant in a sub. In fact, a cube is the *best* enclosure shape for a sealed-box sub, as it has maxium wall rigidity for any given volume and material. If you go for the suggested model with 3" as the smallest dimension of manifold and slit then you have to make some kind of a transition from the 13" membrane. This is not about midrange, so doing it the crude way comes to mind, i. e. starting the manifold with a - tja da dum - 3 by 13 inches or 3 by 10 inches initial area. Even to simply enter the room with the membrane area will then require expansion. You can however transit directly from a 13" circle to a 3" x 44" slit (to maintain equal areas) without any expansion whatever, simply by making a double-tapered box, so why bother with an intermediate constriction? BTW, such a manifold box will have minimal resonance problems due to the heavy taper of the box sides, so it's also a mechanically sound design not requiring heroic wall thickness. I'm still looking at a manifold exit area of 0.3-0.5 the Sd of the two drivers (for improved WAF....) , expanding into the 1/8 space of the room corner. As you say, there may need to be a back box to equalise cone loading. Ah, going to the room corner is a mitigating factor because it allows you to use the corner as an extension of the conical horn in the manifold. And with an "L" shaped slit in the ceiling in the corner it ought to be possible to make it a lot more compact than I had first thougth. I currently favour a 10" square aperture, which is reasonably discreet and gives a 3:1 area compression from a pair of 15" drivers. Might have to be a foot square to allow for grille solidity. OTOH, since I'm staying well below Xmax for normal operation, perhaps this is all a little paranoid! OTGH, design time costs me nothing, so why not do it right first time.................. Minimizing distortion and getting an optimum coupling to the room are worthwhile aims and probably pre-requites for a system that is supposed to be able to play well in trippel forte as well as in the way more difficult trippel piano. Indeed so, hence lots of thinking before firing up the jigsaw! Try searching for hornresp ... it may be possible to express this as a conical horn it can understand, in which case it could be helpful to try modelling in it. Aside from the basic expansion into 1/8 space given by corner mounting, I have no intention of getting into the multitudinous problems of horns! -- Stewart Pinkerton | Music is Art - Audio is Engineering |
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Adire Tempest Downfiring Ported Subwoofer Project : Polyfill Concerns
Sorry guys - I missed the start of this thread, and I've been watching ever
since to find out just what is an "IB"? Tony (remove the "_" to reply by email) |
#111
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Adire Tempest Downfiring Ported Subwoofer Project : Polyfill Concerns
Sorry guys - I missed the start of this thread, and I've been watching ever
since to find out just what is an "IB"? Tony (remove the "_" to reply by email) |
#112
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Adire Tempest Downfiring Ported Subwoofer Project : Polyfill Concerns
Sorry guys - I missed the start of this thread, and I've been watching ever
since to find out just what is an "IB"? Tony (remove the "_" to reply by email) |
#113
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Adire Tempest Downfiring Ported Subwoofer Project : Polyfill Concerns
On Mon, 29 Dec 2003 01:40:54 +1000, Tony Roe
wrote: Sorry guys - I missed the start of this thread, and I've been watching ever since to find out just what is an "IB"? Infinite Baffle. Eithee a *very* large plate to which the drivers are attached, or more reasonably, fitting the drivers in the wall between two rooms. -- Stewart Pinkerton | Music is Art - Audio is Engineering |
#114
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Adire Tempest Downfiring Ported Subwoofer Project : Polyfill Concerns
On Mon, 29 Dec 2003 01:40:54 +1000, Tony Roe
wrote: Sorry guys - I missed the start of this thread, and I've been watching ever since to find out just what is an "IB"? Infinite Baffle. Eithee a *very* large plate to which the drivers are attached, or more reasonably, fitting the drivers in the wall between two rooms. -- Stewart Pinkerton | Music is Art - Audio is Engineering |
#115
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Adire Tempest Downfiring Ported Subwoofer Project : Polyfill Concerns
On Mon, 29 Dec 2003 01:40:54 +1000, Tony Roe
wrote: Sorry guys - I missed the start of this thread, and I've been watching ever since to find out just what is an "IB"? Infinite Baffle. Eithee a *very* large plate to which the drivers are attached, or more reasonably, fitting the drivers in the wall between two rooms. -- Stewart Pinkerton | Music is Art - Audio is Engineering |
#116
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Adire Manifolding, was " Adire Tempest Downfiring Ported
Stewart Pinkerton wrote:
Expansion prevents too many parallel walls. Which are completely irrelevant in a sub .... We are not in the sub, we are on the way into the living room to stir the coffee. You can however transit directly from a 13" circle to a 3" x 44" slit (to maintain equal areas) without any expansion whatever, simply by making a double-tapered box, so why bother with an intermediate constriction? To avoid making the double tapered box ... I currently favour a 10" square aperture, which is reasonably discreet and gives a 3:1 area compression from a pair of 15" drivers. Might have to be a foot square to allow for grille solidity. Erm, what happened to the 3# by 44# slit above .... to have the driver chassis vertical wold of course require a 90 degree downwards bend to enter the room. Indeed so, hence lots of thinking before firing up the jigsaw! It could well be an advantage when later negotiating other building permits to have this project well planned and neatly executed and "right at the first go". [re-iterating] Try searching for hornresp ... it may be possible to express this as a conical horn it can understand, in which case it could be helpful to try modelling in it. Aside from the basic expansion into 1/8 space given by corner mounting, I have no intention of getting into the multitudinous problems of horns! The corner *is* a conical horn, whether you want it to so be or not, and seen like that it could be that hornresp can suggest the volume for the rear load chamber as well as give a hint about what kind of frequency response to expect below Fs. Frankly however this is rapidly leaving my field of knowhow, my gut feeling remains however: horn it. Stewart Pinkerton | Music is Art - Audio is Engineering -- ************************************************** ************* * \\\\\\\ Quality Ascii handcrafted by Peter Larsen /////// * * \\\\\\\ My site is at: http://www.muyiovatki.dk /////// * ************************************************** ******* |
#117
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Adire Manifolding, was " Adire Tempest Downfiring Ported
Stewart Pinkerton wrote:
Expansion prevents too many parallel walls. Which are completely irrelevant in a sub .... We are not in the sub, we are on the way into the living room to stir the coffee. You can however transit directly from a 13" circle to a 3" x 44" slit (to maintain equal areas) without any expansion whatever, simply by making a double-tapered box, so why bother with an intermediate constriction? To avoid making the double tapered box ... I currently favour a 10" square aperture, which is reasonably discreet and gives a 3:1 area compression from a pair of 15" drivers. Might have to be a foot square to allow for grille solidity. Erm, what happened to the 3# by 44# slit above .... to have the driver chassis vertical wold of course require a 90 degree downwards bend to enter the room. Indeed so, hence lots of thinking before firing up the jigsaw! It could well be an advantage when later negotiating other building permits to have this project well planned and neatly executed and "right at the first go". [re-iterating] Try searching for hornresp ... it may be possible to express this as a conical horn it can understand, in which case it could be helpful to try modelling in it. Aside from the basic expansion into 1/8 space given by corner mounting, I have no intention of getting into the multitudinous problems of horns! The corner *is* a conical horn, whether you want it to so be or not, and seen like that it could be that hornresp can suggest the volume for the rear load chamber as well as give a hint about what kind of frequency response to expect below Fs. Frankly however this is rapidly leaving my field of knowhow, my gut feeling remains however: horn it. Stewart Pinkerton | Music is Art - Audio is Engineering -- ************************************************** ************* * \\\\\\\ Quality Ascii handcrafted by Peter Larsen /////// * * \\\\\\\ My site is at: http://www.muyiovatki.dk /////// * ************************************************** ******* |
#118
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Adire Manifolding, was " Adire Tempest Downfiring Ported
Stewart Pinkerton wrote:
Expansion prevents too many parallel walls. Which are completely irrelevant in a sub .... We are not in the sub, we are on the way into the living room to stir the coffee. You can however transit directly from a 13" circle to a 3" x 44" slit (to maintain equal areas) without any expansion whatever, simply by making a double-tapered box, so why bother with an intermediate constriction? To avoid making the double tapered box ... I currently favour a 10" square aperture, which is reasonably discreet and gives a 3:1 area compression from a pair of 15" drivers. Might have to be a foot square to allow for grille solidity. Erm, what happened to the 3# by 44# slit above .... to have the driver chassis vertical wold of course require a 90 degree downwards bend to enter the room. Indeed so, hence lots of thinking before firing up the jigsaw! It could well be an advantage when later negotiating other building permits to have this project well planned and neatly executed and "right at the first go". [re-iterating] Try searching for hornresp ... it may be possible to express this as a conical horn it can understand, in which case it could be helpful to try modelling in it. Aside from the basic expansion into 1/8 space given by corner mounting, I have no intention of getting into the multitudinous problems of horns! The corner *is* a conical horn, whether you want it to so be or not, and seen like that it could be that hornresp can suggest the volume for the rear load chamber as well as give a hint about what kind of frequency response to expect below Fs. Frankly however this is rapidly leaving my field of knowhow, my gut feeling remains however: horn it. Stewart Pinkerton | Music is Art - Audio is Engineering -- ************************************************** ************* * \\\\\\\ Quality Ascii handcrafted by Peter Larsen /////// * * \\\\\\\ My site is at: http://www.muyiovatki.dk /////// * ************************************************** ******* |
#119
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Adire Manifolding, was " Adire Tempest Downfiring Ported Subwoofer Project : Polyfill Concerns"
"Peter Larsen" wrote in message
... The corner *is* a conical horn, whether you want it to so be or not, and seen like that it could be that hornresp can suggest the volume for the rear load chamber as well as give a hint about what kind of frequency response to expect below Fs. Frankly however this is rapidly leaving my field of knowhow, my gut feeling remains however: horn it. I've kinda lost track of this thread. If we're still talking about an infinite baffled subwoofer with drivers mounted in a manifold ported into the listening area then it most certainly is NOT a horn. Even at a high frequency of 100Hz the manifold dimensions are less than 1/10 of a wavelength. The manifold will act as a pressure source at the opening into the listening area. Of the hundreds of people who have built an IB sub and posted their results on the IB forum no one has ever used anything other than a square/rectangle opening. Just construct a box from 3/4" plywood, put drivers on opposite sides, make the box as short as possible (drivers as close as possible to listening room) and use as large an opening as possible. Pretty simple, eh? For four 15" drivers using a cube of 18" or so is ideal. Even with two drivers still use a cube as you can easily add two more drivers later if you want more output. Below is a perfect example with response measurements. Just use four drivers instead of twelve. http://t-3.cc/users/audioworx/page13-12Shiva1.html Or you can build a manifold the same width as your rafters and put two drivers on each side. http://t-3.cc/users/audioworx/page25Mini-Me1.html |
#120
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Adire Manifolding, was " Adire Tempest Downfiring Ported Subwoofer Project : Polyfill Concerns"
"Peter Larsen" wrote in message
... The corner *is* a conical horn, whether you want it to so be or not, and seen like that it could be that hornresp can suggest the volume for the rear load chamber as well as give a hint about what kind of frequency response to expect below Fs. Frankly however this is rapidly leaving my field of knowhow, my gut feeling remains however: horn it. I've kinda lost track of this thread. If we're still talking about an infinite baffled subwoofer with drivers mounted in a manifold ported into the listening area then it most certainly is NOT a horn. Even at a high frequency of 100Hz the manifold dimensions are less than 1/10 of a wavelength. The manifold will act as a pressure source at the opening into the listening area. Of the hundreds of people who have built an IB sub and posted their results on the IB forum no one has ever used anything other than a square/rectangle opening. Just construct a box from 3/4" plywood, put drivers on opposite sides, make the box as short as possible (drivers as close as possible to listening room) and use as large an opening as possible. Pretty simple, eh? For four 15" drivers using a cube of 18" or so is ideal. Even with two drivers still use a cube as you can easily add two more drivers later if you want more output. Below is a perfect example with response measurements. Just use four drivers instead of twelve. http://t-3.cc/users/audioworx/page13-12Shiva1.html Or you can build a manifold the same width as your rafters and put two drivers on each side. http://t-3.cc/users/audioworx/page25Mini-Me1.html |
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