JaG,
Well, hardboad costs like nuttin'....so...
And TwisterZ,
It seems like you linked to an image local to your computer... :-(
I'll see what I can fiddle with my scrap speaker: See if I'll manage to alter the chamfer. I'll post the results/my thoughts.
I'm not sure wether the formula I used takes the 'end correction' into account.
Regards, Paul
Well, hardboad costs like nuttin'....so...
And TwisterZ,
It seems like you linked to an image local to your computer... :-(
I'll see what I can fiddle with my scrap speaker: See if I'll manage to alter the chamfer. I'll post the results/my thoughts.
I'm not sure wether the formula I used takes the 'end correction' into account.
Regards, Paul
Searched a bit today at work, and found that 'my' sheet DOES take the end-corr. into account. If you look in cell B8 (And all below!) you'll seebibster said:
(0.008*$B$5)
change that into
($A$5*0,01*$B$5)
and put yer end-correction in cell A5 (0.732), copy cell B8 downwards, and rock'n'roll...
Paul
Sorry about the Pic, not sure how to post it.
I did scale this up for an 18" woofer (Mach5 or FIaudio IB). This started with trying to get an IB to work in my room. The attic space is in the back of the room but I didn't want the outlet in the back of the room. When I read the forum I thought of the space between the ceiling and roof. My roof has 4x12's on 4 foot centers. With the horn and resonator in the ceiling the woofer backwave can be IB to attic and the port would be behind my screen in the front of the room.
I did scale this up for an 18" woofer (Mach5 or FIaudio IB). This started with trying to get an IB to work in my room. The attic space is in the back of the room but I didn't want the outlet in the back of the room. When I read the forum I thought of the space between the ceiling and roof. My roof has 4x12's on 4 foot centers. With the horn and resonator in the ceiling the woofer backwave can be IB to attic and the port would be behind my screen in the front of the room.
If you want to email the picture to me I'll post it for you. I'd still like to see it, as you mentioned the ports taper to a point so I'd like to see what you are up to.
I'm still far from convinced that a driver with "normal" parameters is optimal. But since I really know next to nothing on the subject, I'm wondering if maybe you have previous experience with the design, or maybe just know somehow what type of driver will work. Or are you just guessing, like me?
By the way, if the Mach 5 driver works this could be an incredibly cheap project considering it's output frequencies.
Bibster, I don't know a thing about excel except how to read what I see like a chart. Are you saying that the calculations should be altered to simulate the end correction?
I was under the impression that the calculator I linked to took everything into consideration and would accurately output info based on user input without the need to manually add end correction.
Anyway, at this point I'm not incredibly worried about it. Just last week Moray was about to throw in the towel on this design, relegating it to myth status. At this point I would be be very happy to see a working proof of concept box following the plans(with any driver size) that does exactly what the patent claims it can. Knowing exactly how to mod based on real math will be an incredible bonus, but first I'd like to know that this design does everything it is supposed to, and what kind of driver makes it perform properly. The only reason I brought up any of this was to know how to fix it if it didn't work out as planned when I build from the plans.
This discussion has really brought up as many questions as it has answered, so I believe that I'm personally back to the no cost proof of concept follow the plans box to test smaller drivers I have on hand. I have enough materials to make a (really rough) test box for 10's but unfortunately I will not be able to get into the shop in the foreseeable future.
I'm still far from convinced that a driver with "normal" parameters is optimal. But since I really know next to nothing on the subject, I'm wondering if maybe you have previous experience with the design, or maybe just know somehow what type of driver will work. Or are you just guessing, like me?
By the way, if the Mach 5 driver works this could be an incredibly cheap project considering it's output frequencies.
Bibster, I don't know a thing about excel except how to read what I see like a chart. Are you saying that the calculations should be altered to simulate the end correction?
I was under the impression that the calculator I linked to took everything into consideration and would accurately output info based on user input without the need to manually add end correction.
Anyway, at this point I'm not incredibly worried about it. Just last week Moray was about to throw in the towel on this design, relegating it to myth status. At this point I would be be very happy to see a working proof of concept box following the plans(with any driver size) that does exactly what the patent claims it can. Knowing exactly how to mod based on real math will be an incredible bonus, but first I'd like to know that this design does everything it is supposed to, and what kind of driver makes it perform properly. The only reason I brought up any of this was to know how to fix it if it didn't work out as planned when I build from the plans.
This discussion has really brought up as many questions as it has answered, so I believe that I'm personally back to the no cost proof of concept follow the plans box to test smaller drivers I have on hand. I have enough materials to make a (really rough) test box for 10's but unfortunately I will not be able to get into the shop in the foreseeable future.
Just a Guy,
The sheet 'as it is' takes some end-correction into account: a value of 0.8*diameter. This should be 0.732 according to someones link above. No really spectacular changes it makes, though... (I mean 0.8 or 0.732)
The problem with this box is that it's supposed to 'do its job' in a 'suitable' listening env. (Says the patent) e.g. a fairly well 'sealed' room (says the maker of the .doc that floats around)
Add the fact that we have (hardly) no idea what driver specs to search for.... And we find ourselfes back in trial'n'error land!!!
I don't quite have the means to make measurements, but I don't think the box does what is says it should do: Bang-bang between 5 and 25 Hz. It does go low, I think, though!
This could be the lack of 'suitable' listening env?
Something odd happend with the box the other day: I adjusted my sub-amp (Driven by the same linestage, in //) so it fills in like it should.
Then, I lowered the volume BEFORE the linestage, and I found the box being louder than the mains...
Don't know if this has ANYTHING to do with the box, but.... It is supposed to be efficient with low levels, and lose this efficiency at higher levels... Am I experiencing this? Who knows!
I've got a pair of KEF sp1044 (B139) laying around. I'll try to make a baffle to fit on the box , on the existing hole for the 10", and see what it does.
Keep up the works,
Paul
The sheet 'as it is' takes some end-correction into account: a value of 0.8*diameter. This should be 0.732 according to someones link above. No really spectacular changes it makes, though... (I mean 0.8 or 0.732)
The problem with this box is that it's supposed to 'do its job' in a 'suitable' listening env. (Says the patent) e.g. a fairly well 'sealed' room (says the maker of the .doc that floats around)
Add the fact that we have (hardly) no idea what driver specs to search for.... And we find ourselfes back in trial'n'error land!!!
I don't quite have the means to make measurements, but I don't think the box does what is says it should do: Bang-bang between 5 and 25 Hz. It does go low, I think, though!
This could be the lack of 'suitable' listening env?
Something odd happend with the box the other day: I adjusted my sub-amp (Driven by the same linestage, in //) so it fills in like it should.
Then, I lowered the volume BEFORE the linestage, and I found the box being louder than the mains...
Don't know if this has ANYTHING to do with the box, but.... It is supposed to be efficient with low levels, and lose this efficiency at higher levels... Am I experiencing this? Who knows!
I've got a pair of KEF sp1044 (B139) laying around. I'll try to make a baffle to fit on the box , on the existing hole for the 10", and see what it does.
Keep up the works,
Paul
According to the "Holliman Document" the drivers were supplied by Wilmslow Audio Ltd. I contacted them asking for any information they may have regarding the drivers. Hopefully they will reply back with some specs that will make it easier to narrow down an appropriate driver that we can obtain today.
Measurements (rough...)
Hi,
Well, Put my BOX in my garage, doors wide open, ibook+Audio interface and some softs, and got this.
It confirms my 'feelings': There IS something happening way low...
As you can see, the level goes way down after 20 or z, comes a BIT back, and then stays (relatively) low.
I put the mic. (2" diaphragm electret) next to one of the outlets (5 cm or zo), speaker close to door (== outside world).
Maybe someone can transform this into some response diagram?
(or tell me how I should measure? I'm a mac user, some soft ideas?)
Regards, Paul
Hi,
Well, Put my BOX in my garage, doors wide open, ibook+Audio interface and some softs, and got this.
It confirms my 'feelings': There IS something happening way low...
As you can see, the level goes way down after 20 or z, comes a BIT back, and then stays (relatively) low.
I put the mic. (2" diaphragm electret) next to one of the outlets (5 cm or zo), speaker close to door (== outside world).
Maybe someone can transform this into some response diagram?
(or tell me how I should measure? I'm a mac user, some soft ideas?)
Regards, Paul
Freddi,
I made the 10" version (read a bit higher up in this thread), and I use a (modified) 'elcheapo' shitty driver. I attached an image of it, and on the site it says:
SP-W10-SONO Diam 25cm 300W 8Ohm 92dB freq. 34-5,5K
I have to admit: I don't know how to measure properly, so just placed the mic (No specs neither!) near, very near to the outlet. I thought I'd thus sort of exclude the room (Well, I was allmost outside...)
I know there's something like the proximity effect with mic's, but I think I wasn't close enough the experience that. (Like 5 cm form the 'horn' outlet)
All I heard is in the file The source? iBook + Edirol UA25 @48Khz + Signalsuite.
Paul
I made the 10" version (read a bit higher up in this thread), and I use a (modified) 'elcheapo' shitty driver. I attached an image of it, and on the site it says:
SP-W10-SONO Diam 25cm 300W 8Ohm 92dB freq. 34-5,5K
I have to admit: I don't know how to measure properly, so just placed the mic (No specs neither!) near, very near to the outlet. I thought I'd thus sort of exclude the room (Well, I was allmost outside...)
I know there's something like the proximity effect with mic's, but I think I wasn't close enough the experience that. (Like 5 cm form the 'horn' outlet)
All I heard is in the file
The source? iBook + Edirol UA25 @48Khz + Signalsuite. Paul
Attachments
Hi Mike, and others
I'll re-measure later this week: In my livingroom, which is rather 'sealed', except for the gaps under the 3 doors....
Any hints/tips as to measure 'correctly' ? Any good soft to use on my Macs?
The measurement posted confirms my thoughts about the response being 'wow, thes less, then wow and noting more', and looks like the way I 'feel' it.
Better measurements on the way !
Paul
(Maybe some of the die-hards should jump back on this thread, for some good solid tips for testing?)
I'll re-measure later this week: In my livingroom, which is rather 'sealed', except for the gaps under the 3 doors....
Any hints/tips as to measure 'correctly' ? Any good soft to use on my Macs?
The measurement posted confirms my thoughts about the response being 'wow, thes less, then wow and noting more', and looks like the way I 'feel' it.
Better measurements on the way !
Paul
(Maybe some of the die-hards should jump back on this thread, for some good solid tips for testing?)
for PC I use TrueRTA but its expensive @$US99. ARTA in free demo version should work on a PC but not sure on MAC. (borrow a a pc notebook?) Your mic needs to be flat to below 20. Behringer's ECM 8000 can do 20. Probably OK to measure with mic on floor ~3-4 feet away. make sure nothing in the chain is clipped.
can you set the generator at one frequency and try 10Hz - 12Hz - 16Hz 20Hz and listen for nasty overtones? (or none if lucky) - got spl meter?
ARTA
http://www.fesb.hr/~mateljan/arta/download.htm
can you set the generator at one frequency and try 10Hz - 12Hz - 16Hz 20Hz and listen for nasty overtones? (or none if lucky) - got spl meter?
ARTA
http://www.fesb.hr/~mateljan/arta/download.htm
Mike, I would say that all of this is proof positive that we are definitely on the right track. According to the Akabak and MJK software sims from earlier in this thread there is no way that Bibster's box could possibly exhibit the frequency response that we listened to in the wav file.
I wouldn't bother with all the testing software, mics and all that goes with it. This can be tested adequately by ear (and when it gets low enough, by the butt in seat tactical sensation method) with your tone generator.
That said, my current sub is set up to be audibly flat to 16 hz. I listened to the wav file and I have to say it doesn't sound that bad. Based on previous descriptions I was expecting some really nasty resonant peaks but I didn't hear anything really awful. If it were slowed way down or individual frequencies were played you might notice a bit of objectionable resonance that a room might even accentuate, but I would consider this a good start. I don't know exactly what frequency range was swept, but from what I hear, my first impression is that about a third of the wav file was fairly flat, usable output. From about 8 seconds to 18 seconds. Not as low or as much range as hoped for, but it's a great start.
I wouldn't bother with all the testing software, mics and all that goes with it. This can be tested adequately by ear (and when it gets low enough, by the butt in seat tactical sensation method) with your tone generator.
That said, my current sub is set up to be audibly flat to 16 hz. I listened to the wav file and I have to say it doesn't sound that bad. Based on previous descriptions I was expecting some really nasty resonant peaks but I didn't hear anything really awful. If it were slowed way down or individual frequencies were played you might notice a bit of objectionable resonance that a room might even accentuate, but I would consider this a good start. I don't know exactly what frequency range was swept, but from what I hear, my first impression is that about a third of the wav file was fairly flat, usable output. From about 8 seconds to 18 seconds. Not as low or as much range as hoped for, but it's a great start.
Maybe individual test tones would be a better way of seeing exactly what the box is doing. Test tones can be downloaded from here.
http://www.realmofexcursion.com/downloads.htm
There are separate sine tones from 5 to 20 hz along with various sine sweeps. Paul, you can download them and burn them to a cd to test your sub. It'll probably be easier then finding Mac software.
http://www.realmofexcursion.com/downloads.htm
There are separate sine tones from 5 to 20 hz along with various sine sweeps. Paul, you can download them and burn them to a cd to test your sub. It'll probably be easier then finding Mac software.
Hello Mike (and the rest!)
Thanks for the link, I'll try to download some tones & sweeps.
I'll use me receiver (as opposed to my sub-amp) for testing (Like I did today).
I'll see if I can manage to keep the background noise low (Kill the kids etc. )
Won't be tomorrow (Dentist & squeezebox class....) but maybe some other day this week I'll manage to measure something, If I'm not to late home form work. Otherwise, we'll have to wait 'till next weekend.
Other hints still welcome!
Regards, Paul
Thanks for the link, I'll try to download some tones & sweeps.
I'll use me receiver (as opposed to my sub-amp) for testing (Like I did today).
I'll see if I can manage to keep the background noise low (Kill the kids etc.
)Won't be tomorrow (Dentist & squeezebox class....) but maybe some other day this week I'll manage to measure something, If I'm not to late home form work. Otherwise, we'll have to wait 'till next weekend.
Other hints still welcome!
Regards, Paul