[[email protected]]

Hey everyone, i am about to make my first attempt at building some
front firing home theater subwoofer cabinets, and i'm looking for a
little advice. I know a lot about how to build the cabinets but what
i am looking for is some reassurance that the size of my cabinets will
be sufficient and perform optimally. I am building each cabinet to
house a single 12" woofer pushing around 200 watts. i'm not sure if
the speakers are long throw or short (i got them for free), but if it
helps, the rubber suspension stands about 3/8" out from the frame of
each speaker. The outside dimensions i have decided to make my cabs
are...
18" tall
15" wide
13" deep
with a 1"x13" rectangular vent at the at the bottom on the front
(13" because i will be using 1" MDF and the outside width is 15")
the biggest things i need to know are...
is this cabinet big enough to get a good tone from my subwoofer?
if not what can i do to improve it?
is my reflex vent large enough and how deep should it be?
any suggestions or advice is welcome,
thanks
almfreak

[Serge Auckland]

wrote in message
ps.com...
Hey everyone, i am about to make my first attempt at building some
front firing home theater subwoofer cabinets, and i'm looking for a
little advice. I know a lot about how to build the cabinets but what
i am looking for is some reassurance that the size of my cabinets will
be sufficient and perform optimally. I am building each cabinet to
house a single 12" woofer pushing around 200 watts. i'm not sure if
the speakers are long throw or short (i got them for free), but if it
helps, the rubber suspension stands about 3/8" out from the frame of
each speaker. The outside dimensions i have decided to make my cabs
are...
18" tall
15" wide
13" deep
with a 1"x13" rectangular vent at the at the bottom on the front
(13" because i will be using 1" MDF and the outside width is 15")
the biggest things i need to know are...
is this cabinet big enough to get a good tone from my subwoofer?
if not what can i do to improve it?
is my reflex vent large enough and how deep should it be?
any suggestions or advice is welcome,
thanks
almfreak


What you are attempting to do will almost certainly end in disappointment.
Cabinet and vent sizing is related to the Theil-Small parameters of the
drive units, and consequently, as you don't know what those are for your
particular drive units, you can't get the cabinet and vents sized correctly.

I would get a program like BoxPlot which will calculate the box and vent
sizes from the T-S parameters, and use drive units whose parameters you
know. You'll be doing a lot of work in carpentry, and it would be a pity if
it was all for nothing.

You can get BoxPlot from here.
http://www.speakerbuilding.com/softw...e/boxplot3.zip

S.

http://audiopages.googlepages.com

[[email protected]]

On Oct 26, 5:07 pm, wrote:
Hey everyone, i am about to make my first attempt at building some
front firing home theater subwoofer cabinets, and i'm looking for a
little advice. I know a lot about how to build the cabinets but what
i am looking for is some reassurance that the size of my cabinets will
be sufficient and perform optimally. I am building each cabinet to
house a single 12" woofer pushing around 200 watts. i'm not sure if
the speakers are long throw or short (i got them for free), but if it
helps, the rubber suspension stands about 3/8" out from the frame of
each speaker. The outside dimensions i have decided to make my cabs
are...
18" tall
15" wide
13" deep
with a 1"x13" rectangular vent at the at the bottom on the front
(13" because i will be using 1" MDF and the outside width is 15")
the biggest things i need to know are...
is this cabinet big enough to get a good tone from my subwoofer?
if not what can i do to improve it?
is my reflex vent large enough and how deep should it be?
any suggestions or advice is welcome,

Without any knowledge of the actual operating
parameters of the woofer, there's a high probability
that your cabinet design is wrong. You don't even
have enough information to determined whether
a vent appropriate for the design or not (it's quite
possible that a vented design is a bad idea for
these woofers).

There's certainly nothing to prevent you from just
putting it all together and being done with it. But
if your question is what is the optimum design
for the system, or even what's suitable design,
without the information on the woofers, your
chances of success are very low.

[[email protected]]

well, you're right, since these woofers were given to me for free, i'm
not really sure of the specs, but i did find a brand sticker on the
drivers. It says "Audio Concepts" and nothing more. there is a
number printed on the side of the magnet itself it reads
"1172492/12147". i've searched online for quite some time trying to
find any information i can on these but i can't find any such brand
that sells just the speakers without a cabinet. i dont know what else
to do? any ideas?

[g]

In article . com, wrote:
well, you're right, since these woofers were given to me for free, i'm
not really sure of the specs, but i did find a brand sticker on the
drivers. It says "Audio Concepts" and nothing more. there is a
number printed on the side of the magnet itself it reads
"1172492/12147". i've searched online for quite some time trying to
find any information i can on these but i can't find any such brand
that sells just the speakers without a cabinet. i dont know what else
to do? any ideas?

I have done something like this in the past. Having the drivers you need to know
what the cabinets are. Did you call them ? I had made some cabs using
the approximate size of the commercial units. If all else fails, you can measure
the parameters yourself.

greg

[[email protected]]

i cant find any information on the brand, so i have no way to contact
a manufacturer. the only thing i know is that they are "Audio
Concepts" brand, and i can't find any information on this brand.
There are a few companies out there online with this name, but none of
them sell drivers by themselves. one company sells a 12" powered
subwoofer, but i have no way of being sure that my driver matches the
one in this product... all i know is that mine are 12" drivers with
dual 8 voice coils.

[Peter Larsen[_2_]]

wrote:

i cant find any information on the brand, so i have no way to contact
a manufacturer. the only thing i know is that they are "Audio
Concepts" brand, and i can't find any information on this brand.
There are a few companies out there online with this name, but none of
them sell drivers by themselves. one company sells a 12" powered
subwoofer, but i have no way of being sure that my driver matches the
one in this product... all i know is that mine are 12" drivers with
dual 8 voice coils.

Sorry 'bout mailing instead of posting here .... I have done some more
searching, yeah - it is a lot less simple than I initially thought. My gues
remains that a closed box with 75 liters pr. driver is a good first try.
Fill with loosely fluffed acoustilux or similar whatever, moth protected
sheeps wool is also a good idea.

Forget bass reflex if you do not have exact driver data or the capability of
measuring them. If your listening room architecture permits, then build them
for placement so that the drivers face into each corner.


Kind regards

Peter Larsen

[[email protected]]

i read somewhere that if you dont know what a woofer's specs are you
can make a general guess based on the driver diameter. i.e. 12" driver
means your cabinet should be some multiple of 1 cubic foot. Is there
any validity to this for ported or unported cabs?

[[email protected]]

also, those first box specifications i came up with, i created by
taking the measurements of an 18inch Peavey PA subwoofer, and
decreased them by a ratio of 12/18. i figured that would be a
ballpark estimate if i'm going to be building a high power sub. the
reflex port measurement i generated by using an online calculator that
estimates the port size based on the diameter of the driver and the
maximum reflexion of the driver (which i estimated by measuring the
suspension) at a certain frequency. i used 50Hz because it seemed
that 50Hz seemed to cause the most reflexion and was reproduced louder
that most other frequencies. are these legitimate guesses? or crap?

[g]

In article .com, wrote:
also, those first box specifications i came up with, i created by
taking the measurements of an 18inch Peavey PA subwoofer, and
decreased them by a ratio of 12/18. i figured that would be a
ballpark estimate if i'm going to be building a high power sub. the
reflex port measurement i generated by using an online calculator that
estimates the port size based on the diameter of the driver and the
maximum reflexion of the driver (which i estimated by measuring the
suspension) at a certain frequency. i used 50Hz because it seemed
that 50Hz seemed to cause the most reflexion and was reproduced louder
that most other frequencies. are these legitimate guesses? or crap?


Your just playing around. You can't assume the woofer specs. If
I looked at the woofer, I could say a couple things about it. You don't know
the Qts, so yo udon't know if a ported box is suitable. Drivers are usually
only designed to work in one tupe of box, and the size is also going to
depend on the parameters.

Did you call AC ??

greg

[[email protected]]

On Oct 30, 12:10 pm, wrote:
i read somewhere that if you dont know what a woofer's
specs are you can make a general guess based on the
driver diameter.

Yeah, I read that two. It's still not right, though.

i.e. 12" driver means your cabinet should
be some multiple of 1 cubic foot. Is there any validity to
this for ported or unported cabs?

There is no validity. Take two cases: the 12: woofer in an
AR3A is in a 1.4 cubic foot box. The optimum volume for
one of the old Peerless 12" woofers in a vented cabinet
was about 4 cubic feet. Making a vented system using a
typical musical instrument speaker with a goal of maximum
flat bandwidth could easily lead to an enclosure volume
of a dozen cubic feet.

So, yes, it should be "some multiple" of 1 cubic foot. Whether
that multiple is 1.4, 4 or 12 depends upon the very nature of
the 12" driver.

[[email protected]]

On Oct 30, 12:18 pm, wrote:
also, those first box specifications i came up with, i created by
taking the measurements of an 18inch Peavey PA subwoofer, and
decreased them by a ratio of 12/18.

Sorry, that won't work.

Even given the most simplifying assumptions, it's wrong.
consider, for example, the moving mass of the cone. All
other things being equal, it's NOT going to go as 12/18,
but it's going to go as the SQUARE of that ratio.

So instead of a ratio of 2/3 (12/18), it's more like a ratio
of less than 1/2 (144/324). And that's just ONE parameter.

Making simplifying assumptions like this is almost
guaranteed to lead you to a bad design.

And i figured that would be a
ballpark estimate if i'm going to be building a high power sub. the
reflex port measurement i generated by using an online calculator that
estimates the port size based on the diameter of the driver and the
maximum reflexion of the driver (which i estimated by measuring the
suspension) at a certain frequency.

It would do you well to use the lingua franca of the domain.
"maximum reflexion of the driver" has no standardized
meaning.

As such, it would appear that you are confusing the
temr "Resonant frequency," and, if so, the method you
suggested you used will NOT lead to any meaningful result.

are these legitimate guesses? or crap?

Crap. Simple as that.

[[email protected]]

On Oct 30, 12:18 pm, wrote:
are these legitimate guesses? or crap?

Look, every single person has told you essentially the
same story: without the parameters, you're shooting in
the dark. ONe person did give you a path out that has
a reasonable chance of giving you a usable design, but
it can't use a port.

You can ignore the informed advice being given you, but
you do so at your own peril.

All of the methods you suggested thus far are NOT going
to work. Everyone has pointed this out.

Is their a reason why you doubt this?

[Richard Crowley]

wrote ...
wrote:
are these legitimate guesses? or crap?

Look, every single person has told you essentially the
same story: without the parameters, you're shooting in
the dark. ONe person did give you a path out that has
a reasonable chance of giving you a usable design, but
it can't use a port.

You can ignore the informed advice being given you, but
you do so at your own peril.

All of the methods you suggested thus far are NOT going
to work. Everyone has pointed this out.

Is their a reason why you doubt this?

We could provide references to methods of measuring
the T-S parameters DIY, but it doesn't seem worth the
effort in this case. (Both because of the perceived value
of the speaker drivers, and the perceived willingness of
the OP to do the work.)

[[email protected]]

hey, i'm willing to admit i dont know what i'm doing. and i dont
doubt any of the information anyone has given me on here, i'm just
practicing "learning by asking stupid questions." lol. i just want
to know if i can make anything out of my ingorant assumptions or if
i'm trying to think way beyond my understanding of acoustic physics.
apparently it's the latter case...
is there any easy way to measure the Theil Small parameters of my
drivers?
i've read some information on DIY Theil Small measurements and it
sounds pretty complex...

[Richard Crowley]

wrote ...
hey, i'm willing to admit i dont know what i'm doing. and i dont
doubt any of the information anyone has given me on here, i'm just
practicing "learning by asking stupid questions." lol. i just want
to know if i can make anything out of my ingorant assumptions or if
i'm trying to think way beyond my understanding of acoustic physics.
apparently it's the latter case...

We are saying (many of us from first-hand experience)
that just building random boxes for car speakers has a
very low likelyhood of success or satisfaction.

is there any easy way to measure the Theil Small
parameters of my drivers?

Google returned 620 hits for: measuring thiele-small
I'm certain that there are several good tutorials on the
methodology in that list. Many serious speaker builders
perform DIY T-S measurements. But you will have to
decide whether your particular situation is worth the
hassle.

i've read some information on DIY Theil Small
measurements and it sounds pretty complex...

It is not trivial. That is why most manufacturers of
drivers intended for conventional use will publish
the numbers for your convenience.

But those who make drivers for cars typically don't
bother, because nobody modifies their car to fit the
characteristics of the speakers.

[g]

In article . com, wrote:
hey, i'm willing to admit i dont know what i'm doing. and i dont
doubt any of the information anyone has given me on here, i'm just
practicing "learning by asking stupid questions." lol. i just want
to know if i can make anything out of my ingorant assumptions or if
i'm trying to think way beyond my understanding of acoustic physics.
apparently it's the latter case...
is there any easy way to measure the Theil Small parameters of my
drivers?
i've read some information on DIY Theil Small measurements and it
sounds pretty complex...


You can buy a woofer tester. Costs about a $100. You can also measure it manually.
Click on parameter on this link.

http://www.kbapps.com/audio/speakerd...rs/Default.htm

greg

[Serge Auckland]

"G" wrote in message
...
In article . com,
wrote:
hey, i'm willing to admit i dont know what i'm doing. and i dont
doubt any of the information anyone has given me on here, i'm just
practicing "learning by asking stupid questions." lol. i just want
to know if i can make anything out of my ingorant assumptions or if
i'm trying to think way beyond my understanding of acoustic physics.
apparently it's the latter case...
is there any easy way to measure the Theil Small parameters of my
drivers?
i've read some information on DIY Theil Small measurements and it
sounds pretty complex...


You can buy a woofer tester. Costs about a $100. You can also measure it
manually.
Click on parameter on this link.

http://www.kbapps.com/audio/speakerd...rs/Default.htm

greg

That calculator looks well thought out. If the OP doesn't have even the
minimum test equipment to make these measurements, he shouldn't be thinking
of building his own subwoofer, and should stick to a kit or buy one
ready-made. The TS parameters worked out with this calculator will plug
straight into BoxPlot and calculate the box dimensions.

S.



--
http://audiopages.googlepages.com

[g]

In article , "Serge Auckland" wrote:
"G" wrote in message
...
In article . com,
wrote:
hey, i'm willing to admit i dont know what i'm doing. and i dont
doubt any of the information anyone has given me on here, i'm just
practicing "learning by asking stupid questions." lol. i just want
to know if i can make anything out of my ingorant assumptions or if
i'm trying to think way beyond my understanding of acoustic physics.
apparently it's the latter case...
is there any easy way to measure the Theil Small parameters of my
drivers?
i've read some information on DIY Theil Small measurements and it
sounds pretty complex...


You can buy a woofer tester. Costs about a $100. You can also measure it
manually.
Click on parameter on this link.

http://www.kbapps.com/audio/speakerd...rs/Default.htm

greg

That calculator looks well thought out. If the OP doesn't have even the
minimum test equipment to make these measurements, he shouldn't be thinking
of building his own subwoofer, and should stick to a kit or buy one
ready-made. The TS parameters worked out with this calculator will plug
straight into BoxPlot and calculate the box dimensions.

S.

This seems fairly new and is the cheapest I have seen..


http://www.parts-express.com/pe/psho...number=390-804

[[email protected]]

after several hours of research, i am beginning to believe that my
drivers are in fact a pair of ACI DV12's. I know my speakers are
Audio Concepts and they have dual voice coils and this seems to be the
only ACI, 12 inch dvc speaker i have come across, unless anyone knows
of any others. i have searched for pictures of these drivers to
compare my drivers to but i cannot find anything. but if these
speakers are in fact ACI DV12's i know where to obtain the theil small
parameters. if there is any way anyone could help me confirm this,
please let me know.
almfreak

[bear]

On Nov 1, 1:19 pm, wrote:
after several hours of research, i am beginning to believe that my
drivers are in fact a pair of ACI DV12's. I know my speakers are
Audio Concepts and they have dual voice coils and this seems to be the
only ACI, 12 inch dvc speaker i have come across, unless anyone knows
of any others. i have searched for pictures of these drivers to
compare my drivers to but i cannot find anything. but if these
speakers are in fact ACI DV12's i know where to obtain the theil small
parameters. if there is any way anyone could help me confirm this,
please let me know.
almfreak

As I have a new spare ACI DV12 in the box here, I can tell you it is
marked in black lettering on the dual-stacked magnet: 1174894/DV12
Other characteristics are the black rubber surround, paper cone with
concentric stiffening rings, and vented pole piece.

[[email protected]]

As I have a new spare ACI DV12 in the box here, I can tell you it
is
marked in black lettering on the dual-stacked magnet: 1174894/DV12
Other characteristics are the black rubber surround, paper cone with
concentric stiffening rings, and vented pole piece.

Sounds like my driver matches all of those but the number. here are
some pictures, let me know if this resembles yours. mine has the
black rubber surround, paper cone with concentric rings and the vented
pole piece as well. but not DV12 number!! i did in fact email ACI, but
no replies yet...
http://i126.photobucket.com/albums/p...k/Photo206.jpg
http://i126.photobucket.com/albums/p...k/Photo207.jpg
http://i126.photobucket.com/albums/p...k/Photo208.jpg
http://i126.photobucket.com/albums/p...k/Photo209.jpg

first pic - you can see the cone with the rubber surround and
concentric stiffening rings
second pic - the audio concepts sticker and ported pole piece
third pic - the two stacked magnets
fourth pic - the two coils are currently wired in parallel

WHAT THE HECK IS THIS SPEAKER!?

[bear]

On Nov 1, 5:27 pm, wrote:
As I have a new spare ACI DV12 in the box here, I can tell you it
is

marked in black lettering on the dual-stacked magnet: 1174894/DV12
Other characteristics are the black rubber surround, paper cone with
concentric stiffening rings, and vented pole piece.

Sounds like my driver matches all of those but the number. here are
some pictures, let me know if this resembles yours. mine has the
black rubber surround, paper cone with concentric rings and the vented
pole piece as well. but not DV12 number!! i did in fact email ACI, but
no replies yet...http://i126.photobucket.com/albums/p...k/Photo209.jpg

first pic - you can see the cone with the rubber surround and
concentric stiffening rings
second pic - the audio concepts sticker and ported pole piece
third pic - the two stacked magnets
fourth pic - the two coils are currently wired in parallel

WHAT THE HECK IS THIS SPEAKER!?

Your driver is identical physically to my DV12, still, the FS, Vas,
and Qt may not be the same. If it is a DV12 you want about 2 ft3
sealed...

[[email protected]]

Your driver is identical physically to my DV12, still, the FS, Vas,
and Qt may not be the same. If it is a DV12 you want about 2 ft3
sealed...

2 cubic feet sealed?

[bear]

On Nov 1, 8:53 pm, wrote:
Your driver is identical physically to my DV12, still, the FS, Vas,
and Qt may not be the same. If it is a DV12 you want about 2 ft3
sealed...

2 cubic feet sealed?

Yes 2 cubic feet sealed. This driver was used by ACI in their "Sub 1",
some info:

The classic Sub 1 Synthesized Bandpass (U.S. Patent #5173943)
subwoofer.
http://www.patentmonkey.com/PM/patentid/5173943.aspx

Linear frequency response from 20-90Hz, +-3db
Nominal impedance 4 ohms
Sensitivity: Matches satellites from 86 to 90db 1 watt/1meter
Recommended RMS Power: 70 to 350 watts per channel
12" cast-frame, extended pole piece, rubber surround, down-firing
Adjustment for upper-bass output to optimize system setup
Internal passive low pass filters for sub 90hz 12db
Internal passive high pass filters for satellites 90hz 18db
25 " tall, 13 " wide and 14 " deep (or virtually any shape that
results in 1.9 cu.ft.)

[[email protected]]

thanks a ton man, i appreciate the information

[[email protected]]

On Oct 27, 3:25 pm, wrote:
well, you're right, since these woofers were given to me for free, i'm
not really sure of the specs, but i did find a brand sticker on the
drivers. It says "Audio Concepts" and nothing more. there is a
number printed on the side of the magnet itself it reads
"1172492/12147". i've searched online for quite some time trying to
find any information i can on these but i can't find any such brand
that sells just the speakers without a cabinet. i dont know what else
to do? any ideas?

Sorry to be chiming in late with this, but you can easily reach Audio
Concepts at the contact info listed on their website:

http://www.audioc.com

It is a small company with excellent products that gives great
customer service. Their website has a lot information, including pdf's
of the owner's manuals for all of their speaker lines, even the
discontinued products. They also used to sell speaker kits which might
be how you happened to get a single woofer. I'm sure that someone
there would be happy to give you the info that you need.

GE

[Peter Larsen[_2_]]

wrote:

On Oct 27, 3:25 pm, wrote:

well, you're right, since these woofers were given to me for free,
i'm not really sure of the specs, but i did find a brand sticker on
the drivers. It says "Audio Concepts" and nothing more. there is a
number printed on the side of the magnet itself it reads
"1172492/12147". i've searched online for quite some time trying to
find any information i can on these but i can't find any such brand
that sells just the speakers without a cabinet. i dont know what
else to do? any ideas?

Sorry to be chiming in late with this, but you can easily reach Audio
Concepts at the contact info listed on their website:

http://www.audioc.com

Yes, there is a possibility that the loudspeakers may come from some box(es)
of theirs, but as the questionee pointed out the company name is not unique,
contacting them will resolve whether it is one of their (oem'ed?) products.

It is a small company with excellent products that gives great
customer service. Their website has a lot information, including pdf's
of the owner's manuals for all of their speaker lines, even the
discontinued products. They also used to sell speaker kits which might
be how you happened to get a single woofer. I'm sure that someone
there would be happy to give you the info that you need.

Just for the record, he has a pair.

GE


Kind regards

Peter Larsen