I think Alpair drivers suit the BiB enclosure. But the damping is very important. I think I will give it a try.
17 years now Scottmoose. And still going.
I think I will get close to 30hz - 35hz.
Do you mind me asking what frequency these BiBs with 168Σ were tuned to rather than wading though 295 pages, please?
My understanding is BFH have a three octave range, if this is not true for the BiB there lies a significant advantage.
If so inclined, can someone please inform me what value is "mid Q"? Is this around Qts~0,50?
Thanks in advance.
I am glad Scottmoose is still around!!! He was so kind and patient with my a couple decades ago when I was building my first pair of speakers. My BIBs are now at my son's house. The name brand floor standers he had became his surround speakers once he tried them in the room with the lower ceiling. They didn't sound that good in a room without a finished ceiling.
Benjamin Webber
Benjamin Webber
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You can use the forum 'search' feature find all references in this thread, though in this case it won't do much good since it's Terry's original BIB, hence predates the BIB calculator and the sketch is sadly not really readable unless someone here has archived it or it's on the web archive, so better to use the BIB calculator, which will likely give you either a ~same-same or a bit better design.
T/S speaker cab design peters out at the driver's upper mass corner (Fhm), so its effective Qts' governs its gain BW; for instance 30 Hz Fs/(3) octaves = 30*2^3 = 240 Hz, then 2*30/240 = 0.25 Qts'.
Fhm = 2*Fs/Qts'
Qts': 2*Fs/Fhm
(Qts'): (Qts) + any added series resistance (Rs): http://www.mh-audio.nl/Calculators/newqts.html
(Rs) = 0.5 ohm minimum for wiring, so may be higher if a super small gauge is used as a series resistor and/or there's other series resistance.
Mid Q? Depends on who you ask IME, but FWIW way back when T/S theory was published it was around ~0.376 according to Altec's interpretation, the mean between the ~0.2 - 0.707 usable vented Qt values, i.e. the range of their driver's specs, so YMMV
.
For reference, Terry's original (which apart from the suprabaffle he added was a direct Imperial conversion of a Fostex design for the FF125K) had external dimensions of 70in x 7in x 14in (HxWxD) assuming 1in build material.
As GM notes, better to use the BIB calculator now, since it provides a consistent alignment across the viable range of drivers.
As GM notes, better to use the BIB calculator now, since it provides a consistent alignment across the viable range of drivers.
You can use the forum 'search' feature find all references in this thread, though in this case it won't do much good since it's Terry's original BIB, hence predates the BIB calculator and the sketch is sadly not really readable unless someone here has archived it or it's on the web archive, so better to use the BIB calculator, which will likely give you either a ~same-same or a bit better design.
T/S speaker cab design peters out at the driver's upper mass corner (Fhm), so its effective Qts' governs its gain BW; for instance 30 Hz Fs/(3) octaves = 30*2^3 = 240 Hz, then 2*30/240 = 0.25 Qts'.
Fhm = 2*Fs/Qts'
Qts': 2*Fs/Fhm
(Qts'): (Qts) + any added series resistance (Rs): http://www.mh-audio.nl/Calculators/newqts.html
(Rs) = 0.5 ohm minimum for wiring, so may be higher if a super small gauge is used as a series resistor and/or there's other series resistance.
Mid Q? Depends on who you ask IME, but FWIW way back when T/S theory was published it was around ~0.376 according to Altec's interpretation, the mean between the ~0.2 - 0.707 usable vented Qt values, i.e. the range of their driver's specs, so YMMV
Correct, I was being lazy. After I posted, I went through 10 pages of search results and not one of them mentioned Fr, not one.
I am a tactile learner, so how about using the Fostex FE168e∑ 8Ω?
Frequency response: 51Hz - 21Hz
Fs: 51Hz
Qms: 5,328
Qes: 0,27
Qt: 0,26
Mms: 8,7g
Vas: 0.837 cubic feet or 23,7L
I spent a half hour writing a post only for the forum to crash and delete it... Got to love technology. Lesson learned if write part of a post, before leaving copy and paste into TextEdit. So this will be lacking all the calculations.
I do have the BIB calculator, however, I have not found any information on how to choose Fr and the affect on BW, especially bass and mid base. As I understand, vinyl does not go below 20Hz, so there is no benefit to a BIB boosting frequency below this point. Correct?
Not only is there the significant cost of subwoofers plus the time to design and build another set of cabinets, please consider the front room has a terrible layout for speakers, based on the advice of another forum, have the replacement Grundig speakers facing the loveseat. By the way, just blew a capacitor on the second Grundig speakers (first one I blew a winding not knowing they are 5 watt speakers, only after looking at the driver itself), so now back to no music. Thus, why I would prefer the base being sufficient enough not to require a subwoofer.
Is this possible with a BIB and 168e∑ or 208e∑? (Sigmas produce a shorter BIB.)
If so, which be the better fit?
I am going to skip ahead and respond to the last paragraph, what does "usable vented Qt values" mean? With the 208EZ having a Qts of 0,18 and a Qts' of 0,20 (using the linked calculator and Rs=0,5Ω) create a beautiful pairing with a BIB? Searching the forum again found no answer.
Where does this formula Fs*2^octave bandwidth come from and what does it produce? The point where the frequency is no longer being amplified by the back horn? With Fs of 42Hz, that produces a result of 42*2^3=336Hz and 0,25Qts' (calculator produces 0,20Qts').
Why is there two ways of obtaining different values for Qts'?
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@Scottmoose , yes, I have the BIB calculator and ran it yesterday evening. My frustration is after nine days or so of searching, I have not found one shred of information regarding Fr.
Additionally, I was concerned about the bass and mid bass outputs, I am understanding a BIB is unable to reach to 20Hz.
Now if the only way to achieve production of bass to the limit of vinyl pressing is to have subwoofers, then guess have to sell the dining table and chairs (the two arm chairs or wedged into a bedroom closet) to make room and create a much better layout.
I been seriously considering it since moved in end of May 2022, doesn't really fit the space (the design of the apartment is bar seating, no dining room), no one visits anyone anymore, and I could figure out another place to eat. However, it is Brazilian rosewood and bought for my by my maternal grandmother for the house she gave me (my family stole it from me, however, good as realize need to ignore them saying I can't ever buy land and build my own house, and have invested my inheritance from Dad to make it possible in ten years), plus hope to be married and be nice for us to have a table to sit at. Now think about it, when Dad and I moved to an apartment, there was no dining table, not even chairs, we sat on the floor, so we could figure something out then. Hmmm.
As for the values, assuming a Fr of 40Hz:
168EZ
208EZ
Additionally, I was concerned about the bass and mid bass outputs, I am understanding a BIB is unable to reach to 20Hz.
Now if the only way to achieve production of bass to the limit of vinyl pressing is to have subwoofers, then guess have to sell the dining table and chairs (the two arm chairs or wedged into a bedroom closet) to make room and create a much better layout.
I been seriously considering it since moved in end of May 2022, doesn't really fit the space (the design of the apartment is bar seating, no dining room), no one visits anyone anymore, and I could figure out another place to eat. However, it is Brazilian rosewood and bought for my by my maternal grandmother for the house she gave me (my family stole it from me, however, good as realize need to ignore them saying I can't ever buy land and build my own house, and have invested my inheritance from Dad to make it possible in ten years), plus hope to be married and be nice for us to have a table to sit at. Now think about it, when Dad and I moved to an apartment, there was no dining table, not even chairs, we sat on the floor, so we could figure something out then. Hmmm.
As for the values, assuming a Fr of 40Hz:
168EZ
208EZ
Found it!
From Scott Moose:
"No. I occasionally restrict line-length with low Fs drivers to keep cabinet height, and driver position to reasonable levels. In a BIB, horn length is determined by 1/2 the wavelength of the tuning frequency. Usually this is set to Fs, or just below, but if you've a low Fs driver things can get out of hand, so I tune a bit higher."
So then how further down in frequency does a BIB go below Fs=Fr?
A 208 has a Fs of 42Hz. For a folded horn, it would have a range of about 16Hz to about 120Hz, though if understanding @GM , a BIB roll off at 336Hz.
From Scott Moose:
"No. I occasionally restrict line-length with low Fs drivers to keep cabinet height, and driver position to reasonable levels. In a BIB, horn length is determined by 1/2 the wavelength of the tuning frequency. Usually this is set to Fs, or just below, but if you've a low Fs driver things can get out of hand, so I tune a bit higher."
So then how further down in frequency does a BIB go below Fs=Fr?
A 208 has a Fs of 42Hz. For a folded horn, it would have a range of about 16Hz to about 120Hz, though if understanding @GM , a BIB roll off at 336Hz.
I didn't look for the 'Fr', just wanted the cab dims to calculate it 'close enough'. Anyway, just now remembered it was for my 'el cheapo' all time fave, the RadioShack 40-1354, so went through some old files just now and found his archived write up.
Yeah, I write offline, then copy/paste and still often manage to miss enough spelling/grammar to require edits.
Re 'Fr', et al, here's a math example we used before making the calculator.
I'm out of date, but historically no vinyl went below ~32 Hz, only special effects RTR tapes, though BIB of course can be tuned much lower if one has the space/budget.
As I previously noted, T/S theory covers a driver's gain BW, so the rest of its BW response is governed by its inductance, acoustic loading.
Re low Qt, 0.5 ohms........ it's just a default and for BIB apps the driver's Qt needs to be pretty high for a typical ceiling height, so significant series resistance such as a matching impedance tube amp or an adjustable pot and/or electronic EQ might be required with low Qt drivers for a flat response if there's not enough room boundary gain.
Re Fs*2^octave bandwidth......exactly what I posted; yes in that example.
Re two ways of obtaining different values for Qts'? ???? Please elaborate because TTBOMK there's only the one way to factor in series resistance.
Yeah, I write offline, then copy/paste and still often manage to miss enough spelling/grammar to require edits.
Re 'Fr', et al, here's a math example we used before making the calculator.
I'm out of date, but historically no vinyl went below ~32 Hz, only special effects RTR tapes, though BIB of course can be tuned much lower if one has the space/budget.
As I previously noted, T/S theory covers a driver's gain BW, so the rest of its BW response is governed by its inductance, acoustic loading.
Re low Qt, 0.5 ohms........ it's just a default and for BIB apps the driver's Qt needs to be pretty high for a typical ceiling height, so significant series resistance such as a matching impedance tube amp or an adjustable pot and/or electronic EQ might be required with low Qt drivers for a flat response if there's not enough room boundary gain.
Re Fs*2^octave bandwidth......exactly what I posted; yes in that example.
Re two ways of obtaining different values for Qts'? ???? Please elaborate because TTBOMK there's only the one way to factor in series resistance.
As previously noted, 1/2 WL, so in your example 42/2 = 21 Hz with room boundary gain usually lowering it a bit more.
Again, just an example! Using the 208e∑ you'll in theory need enough series resistance to get it up to ~0.403 Qts' for flattest low end response depending on room boundary gain, so Fhm = 2*42/0.403 = ~208.44 Hz.
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What the heck, stay up some more, have fun being sick?
Well, I being on SSI am limited on amount of money spent on experiments, last back payment should come Wednesday and be used for this build (believe it when comes, worse case just wait for another opportunity). Plus, I am limited on space, terrible at selling stuff, and so what would I do with a plethora of speaker cabinets?
I can understand. Turns out the reason I am terrible at spelling is because of my auditory processing disorder (ex. can't tell the difference between a short e and a short i sound).
I am not finding the math example searching for Fr. The only question I am left with is what the frequency response looks like with a 40Hz to 45Hz Fr. Worse case, buy a replacement keyboard and mouse, use the tiny television for a monitor, set the PC computer on the floor and sit on the floor to run the program that I am forgetting the name of. Only question is how to get the file onto the computer, seem to remember it having trouble hooking up to the internet (never had a Microsoft OS that liked wireless internet).
However, if about 30Hz (heard this for orchestra) is the lowest frequency, then using a 40Hz Fr would easily reach it, correct?
Well, since you mention it, in searching for more information, did find BIBs using 12 inch drivers. Comes out to a total height of 6'-6" (Faital Pro 12FH500, Fr=45Hz=Fs). This then eliminate having a separate subwoofer. My thought is use the Markaudio Pluvia Seven HD 4" (get the pain over with, rather than buy twice) for the tweeter. I talk to think, by the way. Though(s)?
So increase Qts' by adding resistance?
Thank you for providing a formula for calculating the top roll off. Got me wondering if one for the low end roll off or if mirrors. Doesn't matter if 45Hz Fr gets to 30Hz at F0 or more likely, F3.
Here is what you stated: "2*30/240 = 0.25 Qts'." The other way to calculate is regarding resistance. Very peculiar, never heard of a variable having two values.
Well, I being on SSI am limited on amount of money spent on experiments, last back payment should come Wednesday and be used for this build (believe it when comes, worse case just wait for another opportunity). Plus, I am limited on space, terrible at selling stuff, and so what would I do with a plethora of speaker cabinets?
I can understand. Turns out the reason I am terrible at spelling is because of my auditory processing disorder (ex. can't tell the difference between a short e and a short i sound).
I am not finding the math example searching for Fr. The only question I am left with is what the frequency response looks like with a 40Hz to 45Hz Fr. Worse case, buy a replacement keyboard and mouse, use the tiny television for a monitor, set the PC computer on the floor and sit on the floor to run the program that I am forgetting the name of. Only question is how to get the file onto the computer, seem to remember it having trouble hooking up to the internet (never had a Microsoft OS that liked wireless internet).
However, if about 30Hz (heard this for orchestra) is the lowest frequency, then using a 40Hz Fr would easily reach it, correct?
Well, since you mention it, in searching for more information, did find BIBs using 12 inch drivers. Comes out to a total height of 6'-6" (Faital Pro 12FH500, Fr=45Hz=Fs). This then eliminate having a separate subwoofer. My thought is use the Markaudio Pluvia Seven HD 4" (get the pain over with, rather than buy twice) for the tweeter. I talk to think, by the way. Though(s)?
So increase Qts' by adding resistance?
Thank you for providing a formula for calculating the top roll off. Got me wondering if one for the low end roll off or if mirrors. Doesn't matter if 45Hz Fr gets to 30Hz at F0 or more likely, F3.
Here is what you stated: "2*30/240 = 0.25 Qts'." The other way to calculate is regarding resistance. Very peculiar, never heard of a variable having two values.
Ha, the great thing about the BIB is that it is less complicated to calculate, and less essential to understand the theory of every detail. It is basically a standard recipe that yield a box that is relatively big, but also relatively successful.
The standard recipe, based on the resonance frequency of the drive unit, gives you lower bass extension of half that resonance frequency. So a driver with a 60Hz resonance will lead to a BIB with a 30Hz extension, a driver with a 30Hz resonance will lead to a BIB with a 15 Hz extension.
In practice, it is better if the BIB gets near your ceiling and yet not get the mouth fully blocked, so the room kind of dictates the height and bass extension. Bigger is better, but there is a lot of margin.
I like a quote from the early days of the internet, where someone asked whether a certain loudspeaker driver would work in a certain horn design. Someone answered that "any driver will do something in any horn" but that you will only get a predictable response if the horn was designed for that driver. But I have experienced that it is really true, building a hornloudspeaker is seldom a real waste of time, it will always make sound and sound interesting. A BIB is an easy way to make a horn that is better tuned to a loudspeaker driver. It is the perfect way to jump in and enjoy yourself.
Build one, or a pair, from the cheapest solid material you can find. I once built a loudspeaker from leftover kitchen cabinets I found on the street. It makes it easy to throw away and gives you a chance to try it out in your room.
The standard recipe, based on the resonance frequency of the drive unit, gives you lower bass extension of half that resonance frequency. So a driver with a 60Hz resonance will lead to a BIB with a 30Hz extension, a driver with a 30Hz resonance will lead to a BIB with a 15 Hz extension.
In practice, it is better if the BIB gets near your ceiling and yet not get the mouth fully blocked, so the room kind of dictates the height and bass extension. Bigger is better, but there is a lot of margin.
I like a quote from the early days of the internet, where someone asked whether a certain loudspeaker driver would work in a certain horn design. Someone answered that "any driver will do something in any horn" but that you will only get a predictable response if the horn was designed for that driver. But I have experienced that it is really true, building a hornloudspeaker is seldom a real waste of time, it will always make sound and sound interesting. A BIB is an easy way to make a horn that is better tuned to a loudspeaker driver. It is the perfect way to jump in and enjoy yourself.
Build one, or a pair, from the cheapest solid material you can find. I once built a loudspeaker from leftover kitchen cabinets I found on the street. It makes it easy to throw away and gives you a chance to try it out in your room.
Agree less complicated to calculate, though a number of calculators out there for folded horns. Though, a big advantage for someone who is not a carpenter and doesn't have a table saw, the BIB can be built without cutting angles.
As for understanding it, I had no problem as see it like an organ pipe (some are even made of wood). Additionally, there are open and stopped pipes.
Well, Fs is 45Hz in this example, so if Fr is 45Hz, the extension be 22,5Hz, with the lowest frequency of 22,5Hz.
This again makes me curious what happens when Fs does not equal Fr, an extreme example be adding a tweeter to a BBBIB. When Fr is set to 45Hz, that produces a line length double (the tweeter's Fs is 70Hz) of what is called for.
The recommendation by @Scottmoose for the BBBIB is about 8 to 12 feet, I am smack in the middle. The house (falls into Arizona's tiny house category) I will build has a slopped ceiling, lowest point, which of course where the speakers be placed, is 8'. So these will be a lifetime speaker cabinet.
@Variac had a great idea/realization: OSB being pressed together has no voids. I also have previously come across a high end speaker manufacture using it because the chips didn't vibrate being small pieces of different densities. Additionally, to @Variac and your point, it is it is very inexpensive and last night settled on that for the material.
As for understanding it, I had no problem as see it like an organ pipe (some are even made of wood). Additionally, there are open and stopped pipes.
Well, Fs is 45Hz in this example, so if Fr is 45Hz, the extension be 22,5Hz, with the lowest frequency of 22,5Hz.
This again makes me curious what happens when Fs does not equal Fr, an extreme example be adding a tweeter to a BBBIB. When Fr is set to 45Hz, that produces a line length double (the tweeter's Fs is 70Hz) of what is called for.
The recommendation by @Scottmoose for the BBBIB is about 8 to 12 feet, I am smack in the middle. The house (falls into Arizona's tiny house category) I will build has a slopped ceiling, lowest point, which of course where the speakers be placed, is 8'. So these will be a lifetime speaker cabinet.
@Variac had a great idea/realization: OSB being pressed together has no voids. I also have previously come across a high end speaker manufacture using it because the chips didn't vibrate being small pieces of different densities. Additionally, to @Variac and your point, it is it is very inexpensive and last night settled on that for the material.
You can go a bit lower and it will deviate a little bit from the performance you get from a standard recipe BIB. I expect maximum soundlevel will be lower. But about 0.7 times resonance frequency is acceptable. So 0.7*70=49 Hz. That's prett close to 45Hz and will probably not make a huge difference.
But what is a tweeter in this case? Which drive unit is it?
But what is a tweeter in this case? Which drive unit is it?