First the question.
This is my first time building and I am building floorstanding home theatre speakers. When a driver states its Vas as being a specific value, is that meant to be the cabinet volume required for the driver? Whate are the affects of increasing size or decreasing size?
Next the bigger problem.
Somewhat related is a woofer issue im having with designing a cabinet for the woofer in the dimesions required for my floorstanding speakers. The inside volume i have to work with for the woofer is 6.5 inches wide, 13 inches deep and 25 inches tall. Both the driver and the port must shoot forward in the end. Yes it must be ported. The driver i have has a link listed below with its specs. The reason i havent been able to design an appropriate enclosure is because no matter what route i choose i end up with one critical flaw. WHether, port whistling, or having the port end withing 3 inches of an interior wall (i hear its bad) or port length issues. Im open to any suggestions or ideas. And please correct me if im wrong with ne of my statements. I have attempted using some basic programs which all prove to cause some flaw. Once again any help is appreciated!!
This is my first time building and I am building floorstanding home theatre speakers. When a driver states its Vas as being a specific value, is that meant to be the cabinet volume required for the driver? Whate are the affects of increasing size or decreasing size?
Next the bigger problem.
Somewhat related is a woofer issue im having with designing a cabinet for the woofer in the dimesions required for my floorstanding speakers. The inside volume i have to work with for the woofer is 6.5 inches wide, 13 inches deep and 25 inches tall. Both the driver and the port must shoot forward in the end. Yes it must be ported. The driver i have has a link listed below with its specs. The reason i havent been able to design an appropriate enclosure is because no matter what route i choose i end up with one critical flaw. WHether, port whistling, or having the port end withing 3 inches of an interior wall (i hear its bad) or port length issues. Im open to any suggestions or ideas. And please correct me if im wrong with ne of my statements. I have attempted using some basic programs which all prove to cause some flaw. Once again any help is appreciated!!
Rounder said:
What is the Vas? It is a specification which is essential in calculating the proper volume for your woofer's enclosure. In most cases, the proper enclosure will not be the same volume as the Vas, though it might be. It all depends on the other specifications, such as Qts and Fs, of the woofer.
In one post, I cannot give you a complete tutorial on Thiele-Small parameters.
However, myself or someone else can give you the proper box size for your specific woofer if you post:
A) The Thiele-Small parameters, (Qts, Fs,Vas, etc)
B) How big a box you want-you said ported
C) Dimensions of the box, approximate, you are interested-tall and skinny, or box like?
If I am not still up, some other person will be able to give you a good box size for your woofer.
However, myself or someone else can give you the proper box size for your specific woofer if you post:
A) The Thiele-Small parameters, (Qts, Fs,Vas, etc)
B) How big a box you want-you said ported
C) Dimensions of the box, approximate, you are interested-tall and skinny, or box like?
If I am not still up, some other person will be able to give you a good box size for your woofer.
specs i forgot
DIAPHRAGM MTL Paper
SURROUND MTL Rubber
NOMINAL IMPEDANCE 4 W
DCR IMPEDANCE 3.6 W
SENSITIVITY 1W/1m 83 dB
FREQUENCY RESPONSE 35-800 Hz
FREE AIR RESONANCE 38 Hz
VOICE COIL DIAMETER 38.5 mm
AIR GAP HEIGHT 4 mm
NOMINAL POWER 70 W
MUSIC POWER 140 W
FORCE FACTOR, BL 8.67 TM
MAGNET WEIGHT (oz) Neodymium
MOVING MASS 34.91 g
FERROFLUID ENHANCED No
SUSPENSION COMPLIANCE 423.31MN-1
EFFECTIVE PISTON AREA 0.0140m2
Levc 0.34mH
Zo 33ohm
X-max 13 mm
Vas 11.78 Litr.
Qts 0.40
Qms 2.65
Qes 0.47
i was hoping the enclosure would fit in the dimensions of my original box that i listed in my first post if possible.
DIAPHRAGM MTL Paper
SURROUND MTL Rubber
NOMINAL IMPEDANCE 4 W
DCR IMPEDANCE 3.6 W
SENSITIVITY 1W/1m 83 dB
FREQUENCY RESPONSE 35-800 Hz
FREE AIR RESONANCE 38 Hz
VOICE COIL DIAMETER 38.5 mm
AIR GAP HEIGHT 4 mm
NOMINAL POWER 70 W
MUSIC POWER 140 W
FORCE FACTOR, BL 8.67 TM
MAGNET WEIGHT (oz) Neodymium
MOVING MASS 34.91 g
FERROFLUID ENHANCED No
SUSPENSION COMPLIANCE 423.31MN-1
EFFECTIVE PISTON AREA 0.0140m2
Levc 0.34mH
Zo 33ohm
X-max 13 mm
Vas 11.78 Litr.
Qts 0.40
Qms 2.65
Qes 0.47
i was hoping the enclosure would fit in the dimensions of my original box that i listed in my first post if possible.
Hee hee hee, this is funny.
Having just explained to you that Vas is not necessarily the volume you build the box for, it turns out from your other specs that, in this case, the Vas happens to be exactly the volume you build your box for.
A ported speaker, with a driver of Qts between 0.38 and 0.4, should be built with an internal box volume equal to the Vas and tuned to the Fs-in this case, 38 Hz.
The box you want to build is about three times the Vas of your speaker, and the usual box volume for that speaker.
If you want to wait until tonight, (playoffs are on), I can run a more complex program which can tailor the design to the exact dimensions you are building.
I believe that a ported box can be designed for your woofer-we might just have to change the tuning a little.
Having just explained to you that Vas is not necessarily the volume you build the box for, it turns out from your other specs that, in this case, the Vas happens to be exactly the volume you build your box for.
A ported speaker, with a driver of Qts between 0.38 and 0.4, should be built with an internal box volume equal to the Vas and tuned to the Fs-in this case, 38 Hz.
The box you want to build is about three times the Vas of your speaker, and the usual box volume for that speaker.
If you want to wait until tonight, (playoffs are on), I can run a more complex program which can tailor the design to the exact dimensions you are building.
I believe that a ported box can be designed for your woofer-we might just have to change the tuning a little.
Thanks alot for your help. Your making my life much easier. No big rush with the final dimensions, so enjoy the playoffs, but what i meant is that both the sub and the port would have to be front firing. On the same face as the tweeter and mid. Im not sure if its possible but if it is that would solve all my problems. ONce again thanks for all your help.
A) Usually the walls of a reflex are lined with stuffing, so if the port ends up next to a wall with stuffing on it it blocks some of the air going in.
B) If the interior of the cab wall is bare and the port opening abuts it, it somewhat changes the tuning.
Do you want the sub driver on the bottom of the front? So the mid/tweet is near the top of the cabinet?
Also, how big is the mid and how big is the tweeter? Trying to get a picture of how much space I have to work with here.
B) If the interior of the cab wall is bare and the port opening abuts it, it somewhat changes the tuning.
Do you want the sub driver on the bottom of the front? So the mid/tweet is near the top of the cabinet?
Also, how big is the mid and how big is the tweeter? Trying to get a picture of how much space I have to work with here.
Couple more questions.
A) Is the impedance of the mid and tweeter also 4 ohms?
B) Do you have the crossover worked out yet?
C) The suggestion was made to make the numbers work better by limiting volume through an internal shelf. Another possibility is to add an additional sub driver per cab, to make two per cabinet. You have so much extra volume, it can be easily done, if the sub drivers are not too expensive.
Not saying anything has to be done, just suggesting a possibility.
A) Is the impedance of the mid and tweeter also 4 ohms?
B) Do you have the crossover worked out yet?
C) The suggestion was made to make the numbers work better by limiting volume through an internal shelf. Another possibility is to add an additional sub driver per cab, to make two per cabinet. You have so much extra volume, it can be easily done, if the sub drivers are not too expensive.
Not saying anything has to be done, just suggesting a possibility.
i have a 1 inch vifa tweeter, a 3.5 inch midrange and the woofer is about 6 inches. Because this my first time and im a moron ive allready built a cabinet which is 37 inches tall 8 inches wide and 13 inches deep, which includes the .75 inch mdf. The woofer is meant to go on the botom of the front as u mentioned with teh tweeter and mid on top... ON the inside i have the mid and tweeter in their own sealed enclosure and the woofer has the rest of the room to itself. The divider is about 26 inches up. Leaving plenty of volume to work with , just awkward dimensions for the port. We do have about one inch of stuffing inside the sub enclosure.
its a tang band, the link is http://www.tb-speaker.com/detail/1230_04/w6-1139sg.htm its a very good clean sounding driver, with excellent control and extension for its size.
Anyhow, I ran the simulation, and I can't give you a smooth response using just ported system. You have so much extra volume, it just gives a peaked response at the end.
That means you can either put in a divider to cut the volume to 1/3 what it is now.
Or, I have another way, which would also require a divider, but which will use the full volume of the 25" by 13" by 6" enclosure to your advantage.
I have not yet built one of this type, but it simulates well, and people who have built them seem very satisfied with them, soo.....
If you do use the second type, it will give a response like this-a little peaked at the bottom, but not too bad.
That means you can either put in a divider to cut the volume to 1/3 what it is now.
Or, I have another way, which would also require a divider, but which will use the full volume of the 25" by 13" by 6" enclosure to your advantage.
I have not yet built one of this type, but it simulates well, and people who have built them seem very satisfied with them, soo.....
If you do use the second type, it will give a response like this-a little peaked at the bottom, but not too bad.
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