Not your average sub build... - Page 2

Good morning
I would like to implement the project bandpass 8th
you can have in detail the volumes of the 3 rooms VB1 VB2 VB3, the diameter and length of the ducts?
There are some dimensions to build the box?
What kind of speakers I should use?
You must use some low-pass filter
I would like to try 5-inch speakers with 131 CW Ciara with the following parameters
Re = 3.65 ohm
Fs = 65Hz
qms = 2.7
QES = 0.45
qts = 0.39
mms = 9.7g
cms = 0.61mm \\ N
D = 100mm
Vas = 5.3 dm3
BxL 5.68Wb = \\ m
Xmax = 2.5mm
le = 0.43mH
Regards Fabio Italy

Good morning
I ask you the dimensions for the construction of the box
The characteristics of the speaker used in the design and dimensions of the tubes
agreement.
I read in previous posts I have not found any such data

Yours sincerely
sư tử

Triple Reflex Bandpass boxes are INSANELY complex beasts. I hate to be the bearer of bad tidings, but this box WILL NOT WORK if you are unable to measure the impedance curve.

Here's why:

The triple reflex bandpass box has three impedance troughs, one for each port. That's why you need to measure the curve, and trim the ports accordingly. There are two or three programs which can predict the response, but you have to take them with a grain of salt because all three ports interact with each other.

For instance, if you trim one port it changes the resonance of ALL THREE ports. (Because two chambers are feeding into one.)

If all three ports were terminated on the outside of the box it would be simpler. But the advantage of using one port is a reduction in distortion via the filtering action of the port, and you can also use smaller ports on the inner boxes.

It's a neat project though! I think I have a fairly good grasp on how they work, so if I can help in any way let me know.

Here's more info:

http://forum.audiopsychosis.com/view...=30&p=245#p245

Here is an Akabak script for a triple reflex:

System 'S1'

|================================================= ================================================== =====
|REQUIRED AKABAK SETTINGS:
|File > Preferences > Physical system constants:
|Sound velocity c = 344m/s
|Medium density rho = 1.205kg/m3
|Sum > Acoustic power:
|Frequency range = 10Hz to 20kHz
|Points = 533
|Input voltage = 2.83V rms
|Integration = 2Pi-sr
|Integration steps = 1 degree ... 1 degree
|Integration method = Cross

|================================================= ================================================== =====

Def_Const |Hornresp Input Parameter Values
{
|Length, area and volume values converted to metres, square metres and cubic metres:

S1 = 126.65e-4; |Main Port Throat Area (sq cm)
S2 = 55.59e-4; |Area of main port tube (area betweent the flares)
S3 = 126.65e-4; |Main Port Mouth Area (sq cm)

L12 = 2.54e-2; |Main port segment 1 axial length (cm)
L23 = 12.96e-2; |Main port segment 2 axial length (cm)
L34 = 2.54e-2; |Main port segment 3 axial length (cm)

Vrc = 9.44e-3; |Rear chamber volume (litres)
Lrc = 25.4e-2; |Rear chamber average length (cm)
Ap = 45.6e-4; |Rear port cross-sectional area (sq cm)
Lpt = 77.00e-2; |Rear port tube length (cm)

Vtc = 4.72e-3; |Front chamber volume (cc)
Atc = 550.00e-4; |Front chamber cross-sectional area (sq cm)
Ata = 45.6e-4; |Front port cross-sectional area (sq cm)
Tpt = 36.00e-02; |Front port tube length (cm)

V3c = 19.44e-3; |Third chamber volume (litres)
L3c = 30.0e-2; |Third chamber average length (cm)

|Parameter Conversions:

Sd = 200.00e-4; |Diaphragm area (sq cm)
Arc = Vrc / Lrc;
Ltc = Vtc / Atc;
A3c = V3c / L3c;

}
|================================================= ================================================== =====
|Network node numbers for this horn-loaded vented-box system:
|0-Voltage-1-Resistance-2
| |
| 3-Chamber-4-Driver-5-Chamber-7-Port-12-Chamber-8-Segment-9-Segment-10-Segment-11-Radiator(1)
| |
| --------Port--------------------------
|================================================= ================================================== =====

Def_Driver 'Driver'

Sd=200.00cm2
Bl=18.30Tm
Cms=3.85E-04m/N
Rms=5.68Ns/m
fs=28.90Hz |Mmd = 74.30g not recognised by AkAbak, fs calculated and used instead
Le=2.90mH
Re=7.40ohm
ExpoLe=1

Driver Def='Driver''Driver'
Node=4=0=5=6

Coil 'L1'
Node=1=4
L=4mH
Rs=0.35ohm

Duct 'Rear Chamber'
Node=5=7
SD={Arc}
Len={Lrc}
Visc=0

Duct 'Front chamber'
Node=6=8
SD={Atc}
Len={Ltc}
Visc=0

Duct 'Third chamber'
Node=11=12
SD={A3c}
Len={L3c}
Visc=0

Duct 'Front Port'
Node=8=11
SD={Ata}
Len={Tpt}
Visc=0

Duct 'Rear Port'
Node=7=11
SD={Ap}
Len={Lpt}
Visc=0

Waveguide 'Main Port Segment 1'
Node=13=12
STh={S2}
SMo={S1}
Len={L12}
Conical

Duct 'Main Port Segment 2'
Node=13=14
SD={S2}
Len={L23}
Visc=0

Waveguide 'Main Port Segment 3'
Node=14=15
STh={S2}
SMo={S3}
Len={L34}
Conical

Radiator 'Horn mouth'
Node=15
SD={S3}

the box design is a thing of beauty.
first of all.. it shows proof that the box is a bandPASS design, the other boxes with a sealed front and ported behind.. these are actually bandCUT boxes.

the more common box design with the sealed front and ported back allows two chances of tune.

but this box is sweet because it allows for three chances of tune.
you can tackle the high/middle/low portions of the frequency response without ever having to touch an equalizer.
that means the speaker will play flat outside.
really a desireable thing when you want a huge bump in quality.

if this box design doesnt provide inspiration for box builders.. i cannot imagine what will.

the tuning is insane, because if there is excess room in any of the chambers, the details can get lost OR arrive out of the port late.
with all of that confusion with the different chambers and different ports, you can still get the audio to be released from the main port INSTANTLY.. meaning superb quality.

such a flat frequency response, you can put the subwoofer inside a room and use it to excite the room to learn the 'ringing' frequencies.
see, these subwoofers are generally made small to prevent them from having enough output to cause the ringing in the room.
depending on the size of the room, its very possible to avoid the problem.

a buddy of mine had a bose system with an acoustimass subwoofer, the room was big enough to absorb the wavelengths.
increasing the size of the smallest chamber required increases the 'order' of the design.
like.. if the wave bounces once and leaves the port, thats 1st order.
if the wave bounces against two walls, it is 2nd order. (this requires using a corner and pointing the bounce from the second wall directly to the port.

more 'orders' make the sound more rich (muddy/beefy)
lots of the subwoofers available on the market allow the soundwaves to bounce around quite a bit before leaving the port.. thats how the output sounds as if its coming from a bigger speaker.


dont be so suprised from two 6.5 inch speakers.. they have enough cone area to equal a 13 inch subwoofer.
the xmax is important to make the speaker perform as if there was more than one.

i have two 6.5 inch speakers that i would love to put in a box like that.. but i dont know their parameters to tune the box.

one thing better about the box in this thread.. it has the potential to be tuned for a frequency range, not a single frequency like most ported boxes.
the more common boxes require the speaker to come with a generally flat frequency response with a rolloff.
that rolloff is raised with the port.
and the hardest part, keeping the speaker in the vacuum as detailed in the specifications to actually get the frequency response reported.

thats why those bandCUT boxes are popular.. you build the sealed chamber the correct size for the amount of vacuum needed to get the reported frequency response.. then you use the other side of the speaker to build another box that raises the rolloff.
but the trick is, all of the frequencies that dont require a rolloff boost.. they need to be exiting the port immediately (or as soon as possible)
then the rolloff frequencies linger around in the ported chamber to build up amplitude before being released by the port.

its unreal..
because if the ported chamber is the right size, and the port is the right size.. all you gotta do is put the port in the appropriate place.
most often, they put the port towards the very back of the chamber.. right next to the wall.
that allows the frequencies that dont need a rolloff boost to flow to the wall and simply raise up out of the port.
rolloffs are usually in the lower range for subwoofers, so the soundwave will hit the wall with much more energy, and the extra energy means the wave will ignore the port and continue to bounce around inside the chamber until the pressure in the chamber rises and the excess pressure is released from the port.

if you want to increase the upper rolloff of the subwoofer,
you simply decrease the size of the sealed chamber and add that amount to the ported chamber.. but you place the port close to the wall of the sealed chamber.
the trick, you gotta calculate the ported chamber size to continue to function at the desired tune frequency.. otherwise the tuned frequency will become lower when you add the sealed chamber to the ported chamber.

what is cute?
if the tuned frequency is too high, there will be a massive increase in amplitude at the low end (massive = more output than the upper frequency range)
all you gotta do then is lower the tune of the ported chamber.


i had an MB quart rwe302 12 inch subwoofer in a bandpass box that sounded fantastic.
people who dont build the bandCUT boxes correctly, they will tell you that the box will reduce the clarity of the audio.
but if you build the box correctly.. its superb.

anyways.. the box shown in this thread is MORE complicated.
congrats on getting the box to sound well.

Terrific thread! Thanks for all the photos. I can't think of another thread where I've seen anything similar.

I think i have 2 of the bose drivers from that box out in my garage....i always wanted to do the same project that you have done but never got around to it...........

That amp you have is a great start...way too much power for the Vifa's and their xmax @4mm is pretty small ( i'm not bashing) just be careful as stated above with the gain.
Good Luck...................These guys are great here at helping people out.

Found 1 of them...now where did i put the other........thats why i hate to save anything anymore....Anyway still a great build....I showed this thread to a friend and the first thing he said was remember back in 95 when we were going to build one of these....we built a 6th order using MTX car subs......I actually couldn't hear any bass from the thing and it was huge !.....

That's nowhere close to being true.

one 6.5 inch speaker with .5 inches of xmax + one 6.5 inch speaker with .5 inches of xmax = one 13 inch speaker with 1 inch of xmax

you are obviously talking about the proper ability to use stereo and seperating the speakers to fill the room with sound a bit better.

suggesting anything less is a clear sign of confusion.

i had two 6.5 inch speakers.. each in a ported box tuned to about 40hz
those things were enough to wiggle the rearview mirror and the side mirrors.
at peak output, you could feel it in your chest.
it was a hatchback, so i didnt have to pump the SPL through a backseat.


xmax and cone size is simple.. you failed at making a valid point, so i am wondering if you are simply trying to make trouble.

6.5 inch from one side to the other.. the radius is 6.5 inches all around.
sure the square inch is bigger, but you arent seeing things clearly.

if you unfold and cut the cone on a 6.5 inch speaker, all pieces WONT lay on half of the cone on the 13 inch driver.

i feel your love, unfortunately.
if you dont think square root is a killer, try stereo!!

less excursion?
thats of course a problem..
if you are gonna buy small subwoofers and expect some output, they need to be high excursion.

extra excursion can compensate for the diameter difference.
BUT
putting one speaker on each side of the room will have higher benefits than one large speaker.

funny this here.. because the 13 inch speaker in the middle between two walls, first of all.. the sound is more directed and narrow.
sure, you could use some sound processing to make the speaker blend with the room.. but even then, i wouldnt be at a total loss.
seperate speakers (one on each side of the room) can still reap the benefit of true stereo.

the only way to make the 13 inch woofer work in the middle of the two walls..
well you would have to have a completely empty room with costly reverb.

the fact, energy needs a source.. and until you completely hide the source, those two speakers can have lots of competition if the larger speaker doesnt have loads more excursion.


i think this is a good example of taking the economical choice rather than the brute force option.
it would take some audio mastering to make that one 13 inch speaker sound as good as two half-sized speakers seperated far apart.
could be a thousand dollars in hardware (and an empty room)

now, when considering a 13 inch speaker in a sealed box, compared to the two smaller speakers in a ported box.. the fight would be well worth a viewing.

economical class here.

maybe i am blinded by the hate of far too directional and narrow sound from a single speaker = my love for stereo
or
maybe it is realizing the situation needs manipulation to hold any competition.
realizing the manipulation needed.. it could be argued that two of the smaller speakers hold their own without embarassment.

you are gonna immediately say the 13 inch speaker has equal or more excursion
is also in a ported box
has more wattage
and has been calibrated with sound processing to produce a stereo sound

?

thats a lot compared to laying the box on the floor and wiring it to the amplifier and pressing play.



as i said.. square root has tried to cause embarassment, and i put out the fire with stereo or ported smaller vs sealed bigger

i'm not quite embarassed yet
cant be so narrow and straightforward, otherwise we wouldnt be hearing sharing principals.

your picture really did rain on my parade

to call me wrong, you would have to enforce that both speakers are close together and that they have inferior excursion.

but like i said, getting small speakers for subwoofers.. its only natural to require more excursion.

see, those numbers you presented actually help my arguement.

one 13 inch at 132 inches squared
two 6.5 inch at 66 inches squared

all i need is double the excursion to push on the air twice as much = the same amount of air energy.

i was wrong to say that xmax being the same will provide the same amount of air energy.
but as i got into the details.. i have created a match with superior results.


sorry for those who didnt catch on immediately.
i suppose it isnt fair that the two speakers are in the same box and it was assumed i was talking about both speakers being in the same box.

pro's and con's people.
i'm good with 'em.

so as i said, dont be so suprised if two 6.5 inch subwoofers hold a strong competition (or even find the situation to be superior if you believe in stereo)



see.. this subwoofer has 13mm of xmax (dunno if its one way or two)
http://www.parts-express.com/pe/show...number=264-832

this one has 9mm of xmax (one way)
http://mobile.jlaudio.com/products_s...p?series_id=29

my first post didnt say all thing would be fair

i mentioned suprise and was called on it.
so i brought out the in-depth details to reveal how the surpise works.


another example:
if one 12 (cheap subwoofer that doesnt move in and out without distorting)
two of those JL audio 6.5 inch subwoofers would save space, and hold value.

but i prefer to be ignorant with a reason.

not stereo as in seperate information of left and right channels..
stereo, like chorus, as in a surrounding affect.

anyways.. i wouldnt rule that i took the thread far away from the original subject.. especially with my first post talking about smaller speakers being capable.

unfortunately,
i never ever said the smaller speakers had half the excursion.
thats clear mental processing that amounts to insanity.
i said they have enough cone area to equal a 13 inch speaker.
and if the excursion of the 6.5 speakers is double that of the 13 inch speaker.. it would be equal.

i wasnt false or invalid..!
i just wasnt as direct to the point, and people started crying.

anyways.. i agree, going on and on about it has really made me upset.. because my first reason for posting in this thread was to hold the speaker design way up high, for other people to be proud of human design capabilities.
complexity offers rigorous improvement.


but..
how does talking about the speaker size used in the box amount to 'much different' than intended?
because i am not talking about the box specifically.. instead talking about the characteristics of the box and what makes it special?
if you wanted people to go on and on about:
wood grain
wood type
complexity of the design
quality of the new amplifier
quality of the new speakers
or how inserting the amplifier into the box probably ruined the tune of the box
or even the sticker that was used on the box


i think i went into detail about the most intelligent aspect of the thing.
the economics of it all is the reason why it deserves respect.
how was i supposed to know people would fight a losing fight?
sorry indeed that it happened.. but i didnt request anybody to post about it any further.
they did that with their own choice making.

i hope you place that subwoofer next to some cheap $30 speaker in a small junk box (sealed) and you win the race of output quality.
i went into grave detail about how it could.

i am mystified how you could predict how people would react.
my parents used to yell at me and say 'its their choice not yours'

i chose to say why the sub build isnt 'average'
got pulled aside because of a comment.
i see you blaming me for the direction of the thread.. and i dont feel its fair or even valid.

**edit**
i dont have any desire to continue being in a mess.. i'm gonna stay out of the thread so you have a chance to clean things up.
glad to hear you spent some good time with your dad.
i know at times i wished i spent more time with my dad and had some projects to remember the time spent together.

A lot of words being used to talk about something very simple!

If you want to compare two small drivers to one bigger one, in terms of maximum displacement limited output, then it's a simple matter of volume displacement (VD) = effective piston area (SD) x xmax x 2

Typical driver SD values:
http://redspade-audio.blogspot.com/2...is-driver.html

6.5" 135 cm2
12" 500 cm2

You will need four 6.5" drivers to match the SD, but the bigger driver will most commonly have greater xmax and lower fs.

i read the thread from beginning to end before i posted.
i think you did it about right.
increase the size to compensate for the bigger speakers.
'blowing up' the measurements is as good as you can get without being an experienced box builder.

people use the general method most times.
and most times it works because the products are made for eachother.
its advanced knowledge/training that brings advanced results.
seperating these two types of people can be just as hard as bringing them together.


anyways.. i didnt get off topic.
i dont think a single comment is enough to be considered 'derailing'
'comment' comes first.. then anything associated with that comment is the 'derailing'
that means anybody who replied after is the real problem.
i'm a genius, i know these things


i know i said i was done, but you said dont get upset..
and besides, i have a present..!
have you thought about using 'flared' ports?
something like this:
http://www.parts-express.com/pe/show...number=268-348

but that is bogus because only one side has the big flare.
i remember a company named 'aero ports'
they boasted having extra big flares on each end to eliminate port noise.

maybe you and your dad can sit down together and take the box apart to add the new ports and re-stain the panels before putting it back together?
i know what its like to break a team effort.
when i was a kid, i used to really hate moving the blanket after being tucked in.
it felt like i was totally ruining something my parents did for me.

SALVE COME POSSO AVERE IL PROGGETTO DEL SUB WOOFER SONO INTERESSATO