The spreadsheet looks fantabulous!
I can change line length and watch the numbers recalculate. Question is, how is it altering performance. Or after entering the speaker values should the numbers be left alone?
In other words, can i modify what's considered correct and make changes that will still sound good.
Godzilla
I can change line length and watch the numbers recalculate. Question is, how is it altering performance. Or after entering the speaker values should the numbers be left alone?
In other words, can i modify what's considered correct and make changes that will still sound good.
Godzilla
Very cool!
I'm playing with the spreadsheet and have some questions. My 166e BiBs measure out @
Line - 144"
sm - 88^2"
z-drv - 28"
yeilding a ratio of 1.79 ... and I am really enjoying them a great deal. I'm still amazed at just how low these things go.
Now, if I used the spreadsheet dims of
line - 134.65
sm - 116.26
z-drv - 29.22
ratio - 1.41
What changes might I expect?
There are certainly more BiBs on the horizon
7/10
I'm playing with the spreadsheet and have some questions. My 166e BiBs measure out @
Line - 144"
sm - 88^2"
z-drv - 28"
yeilding a ratio of 1.79 ... and I am really enjoying them a great deal. I'm still amazed at just how low these things go.
Now, if I used the spreadsheet dims of
line - 134.65
sm - 116.26
z-drv - 29.22
ratio - 1.41
What changes might I expect?
There are certainly more BiBs on the horizon
7/10
Godzilla said:
You should be able to adjust the dimensions a bit Jeff; a longer line will go lower; so long as you preserve Vb, though tuning too low will cause problems in the mid - upper bass. Best to stick to the ~optimal ones IMO. That's why I didn't add any extra options to my own little sheet.
giantstairs said:
Greets!
Yeah, with a tiny, high Fs driver (big tweeter) this would be the preferred way IMO, but it looks good in T.C.'s original pipe if some series R is used, though of course its dynamics will be limited down low by however much corner gain is available. No corners = no way IMO though.
GM
Svein_B said:
Greets!
1) T.C.'s is an octave lower (Fs/2 or 100%), so that's the 'standard', though it can be whatever you want it to be as long as you understand the excursion limited dynamics a low tuning can cause. Then there's the size issue of tuning a low Fs driver that far below.
2) The formula is a much simplified T/S Vb formula used in an early HP pocket calculator program by Garry Margolis of JBL and Richard Small (the 'S' in T/S) back in '80 with the exception that I reduced the Qts exponent from 3.3 to 1.25 to account for the ultra fast pipe taper a theoretically zero throat area has, ergo probably only suited to these, but I haven't done any sims to see how they would compare to MJK's mathematically more correct classic TL alignments, so I could be wrong.
GM
Svein_B said:
Greets!
Well, there is a point of diminishing returns, but a doubling of 'Sm' would definitely be worthwhile if the larger value was calc'd using my formula if for no other reason than it allows more tuning flexibility.
As has been noted numerous times in this thread, this ratio is the preferred one since it best preserves the expansion through the bend, not because it looks pleasing to the eye/whatever. That said, as long as the ratio doesn't get so far off from this to the point where it represents enough of a constriction to cause audible modulation of the driver, I wouldn't be concerned about using whatever ratio was required to make the driver fit/whatever.
GM
Godzilla said:
Greets!
'Correct' is a floating target based on the driver's excursion limitations, room placement, etc., with T.C.'s original alignment being merely the 'default' one, so not the 'correct' one per se, only 'correct' for the 40-1354 and any other driver with similar specs if you believe it will play loud enough in your room to suit you.
Calcing a pipe horn using its T/S specs is strictly a starting point, so if you want the driver at a different height than the default tuning calcs, then change the driver's Fs to suit. Ditto lowering/raising Qts if you want a smaller or larger 'Sm' than the default calc, or change both if need be, though of course unless you know what trade-offs to expect performance wise I recommend you sim it before 'burning' wood.
For instance, you probably want to tune a low Fs driver much closer to Fs than an octave below, so increase Fs up to 2x (tuned to Fs) to get the basic height, etc., dims and since the calc'd Vb is based on a lower tuning, Qts could be lowered by the same ratio as the increase in Fs without any real penalty.
GM
I'm playing with the spreadsheet too
And for the 168ESigma I put
Fr= 51Hz
Qts= 0.26
Sm= 23.70L
And gives me
L= 132in
Zd= 28.65in
Sm= 81.36in^2
The revised version as posted here is
L= 138in
Zd= 30in
Sm= 74.25in^2
Which one of the two, do you suggest me to build?
I have the drivers and I found locally 20mm Birch Plywood. I'm in the process to build them asap!!
And for the 168ESigma I put
Fr= 51Hz
Qts= 0.26
Sm= 23.70L
And gives me
L= 132in
Zd= 28.65in
Sm= 81.36in^2
The revised version as posted here is
L= 138in
Zd= 30in
Sm= 74.25in^2
Which one of the two, do you suggest me to build?
I have the drivers and I found locally 20mm Birch Plywood. I'm in the process to build them asap!!
Thanks GM!
At the first case the driver will be 37.35in from the floor and the second at 39in. Not a big difference. What I like at the second case is that it has less depth (if I'll use width= 7.25in in both cases and ratio = 1,4142). My room is a little bit small.
By the way ,which is the ideal height for a driver?
At the first case the driver will be 37.35in from the floor and the second at 39in. Not a big difference. What I like at the second case is that it has less depth (if I'll use width= 7.25in in both cases and ratio = 1,4142). My room is a little bit small.
By the way ,which is the ideal height for a driver?
stroop said:
Greets!
As I noted, nothing's 'cast in stone' and since this is a fairly low Fs driver a higher tuning than 'standard' seems a more reasonable alignment, though even a 'standard' height BIB may be too large for some:
http://www.diyaudio.com/forums/showthread.php?postid=1307286#post1307286
For example, using the 'standard' T.C. tuning of 48.78 Hz based on MJK's worksheet's 342 m/sec SoS rather than the Excel's SS too high value (IMO) to get the same height, driver location, then to calc the somewhat smaller 'Sm' and associated dims:
Fs ratio = 30/48.78 = ~0.615
Qts reduction = 0.317*0.615 = ~0.195 Qts
GM
Attachments
You're welcome!
Like most things, 'ideal' is a floating target based on a number of variables, not the least of which is personal preference, but the standard 'rule-of-thumb' (ROT) is the driver at the in-room average seated adult ear height, so the 32-40" range for a baffle perpendicular to the floor is the norm. Personally, I prefer them somewhat above my head and angled down since it's closer to the presentation I get at a typical live event and it has the advantage of not negatively interacting with the room as much if the floor is carpeted.
Like most things, 'ideal' is a floating target based on a number of variables, not the least of which is personal preference, but the standard 'rule-of-thumb' (ROT) is the driver at the in-room average seated adult ear height, so the 32-40" range for a baffle perpendicular to the floor is the norm. Personally, I prefer them somewhat above my head and angled down since it's closer to the presentation I get at a typical live event and it has the advantage of not negatively interacting with the room as much if the floor is carpeted.
resident said:I'm playing with the spreadsheet too
And for the 168ESigma I put
Fr= 51Hz
Qts= 0.26
Sm= 23.70L
And gives me
L= 132in
Zd= 28.65in
Sm= 81.36in^2
The revised version as posted here is
L= 138in
Zd= 30in
Sm= 74.25in^2
Which one of the two, do you suggest me to build?
The diference between the two spreadsheets is the formula used ti calculate line length...
I used as stated in 'Zillas pages,
Length = 13464,54 / (2 *Fs)
While Scott uses
Length = 13560 / (2 * Fs)
Both have been mentioned in the thread previously, and both have to do with wavelength of the sound in the air, so both are affected by temperature (this one weighs a lot), pressure, humidity and a whole lot of minute factors...
This is a starting point for experimentation so I think both are equally valid. As they are embedded in Excel spreadsheets, both can be altered at will too
Gastón
I was playing with the spreadsheet again and I can't understand how the corrected Zd is calculated!
Any help?
EDIT: Oh, I see that you calculate it as, corrected Zd=0.2*(corrected height*2)
I was using this formula Zd=L*0.217 ! And the corrected Zd for the FE168EZ is 29.14in instead of 26.86in.
Must this be corrected or it isn't so critical?
Any help?
EDIT: Oh, I see that you calculate it as, corrected Zd=0.2*(corrected height*2)
I was using this formula Zd=L*0.217 ! And the corrected Zd for the FE168EZ is 29.14in instead of 26.86in.
Must this be corrected or it isn't so critical?
Well, I just discovered that diference myself... IMO it should be 0.217, as this part of the WS lets people like me, that can't get wood cut to 0.01 mm , plug in what they got, and know how would the dims have to be corrected and those that have the simulators do their magic.
BTW, that 0.017 means a 10% difference so IMO it should be corrected.
Gastón
, plug in what they got, and know how would the dims have to be corrected and those that have the simulators do their magic.BTW, that 0.017 means a 10% difference so IMO it should be corrected.
Gastón
Fellow pipe-horn enthusiasts: another one of my occasional music-recommendations. I don't know how many of you saw the movie Gosford Park, but trust me, you need to hear the soundtrack album. I'm not entirely BIB-less at the moment. I still have a pair of test boxes in the garage, so I screwed my 126s into them this morning. It sounded good in my MLTLs. It sounded sensational through the BIBs.
The recording is first-rate: one of the finest I own (and I don't say that lightly -this is reference quality). The performances are slick, especially the actor, Jeremy Northam's wonderful, wonderful rendering of some Ivor Novello songs, both comic and romantic. Mellow, wistful, perfect diction & phrasing, delightful humerous touches, lovely tone. An absolute delight. The rest is as good, from variations on a central theme through some excellent trad-jazz & classical.
Not your cup of tea? Nope, it's not mine either normally, but this transcends normal musical taste. Late evening. Make a whisky or brandy & soda, stick this on, with dimmed lights (not a blackout), put your feet up with your significant other & indulge in a bit of that delicious late 1920s - early 1930s sophistication that has been lost for so long. Do yourself a favour & try it, if for no other reason than hearing what pipe-horns can do with recordings of this type & using it to shock your friends with sonic realism when they come round.
The recording is first-rate: one of the finest I own (and I don't say that lightly -this is reference quality). The performances are slick, especially the actor, Jeremy Northam's wonderful, wonderful rendering of some Ivor Novello songs, both comic and romantic. Mellow, wistful, perfect diction & phrasing, delightful humerous touches, lovely tone. An absolute delight. The rest is as good, from variations on a central theme through some excellent trad-jazz & classical.
Not your cup of tea? Nope, it's not mine either normally, but this transcends normal musical taste. Late evening. Make a whisky or brandy & soda, stick this on, with dimmed lights (not a blackout), put your feet up with your significant other & indulge in a bit of that delicious late 1920s - early 1930s sophistication that has been lost for so long. Do yourself a favour & try it, if for no other reason than hearing what pipe-horns can do with recordings of this type & using it to shock your friends with sonic realism when they come round.