how to make your own fathom

[metalrake]

http://s617.photobucket.com/albums/tt260/metalrake/?action=view&current=subbox001.jpg

http://s617.photobucket.com/albums/tt260/metalrake/?action=view&current=subbox005.jpg

hi,
i have alot of questions now. sorry

is this enough bracing? if not, do you have any ideas? should i double up the wood on the front? double front baffle(is this what it's called)?

i'm going to pickup the driver monday. waiting to get a deal on the amp and eq if possible. if not should i get the ep4000 or is it the same as the 2500?

i'm going to order the little parts and i don't know what i need and don't want to have to keep paying shipping charges. can anyone help me with this?

do i need dampening material?

what conectors do i buy to connect the driver to the wire? soldier?

what connectors to connect to amp? to eq?

any binding post you recommend? if i cut out a hole for the binding post plate do i need to add material behind it?

i want a grill. recommend any? do i make a grill frame? buy one?

think i might cover it in black ash laminet? any ideas on that?

sorry for so many questions...if anyone can answer any of them i'd appreciate it.

think i got in over my head a little, but might as well learn,
thanks,
sean

 

[annunaki]

Sean,

This looks very nice. Good work. You can add some 8lb/ft^2 mineral wool for damping on three of the internal panels. The material should be placed opposite an uncovered panel.

These binding posts can be purchased without a plate. They are long enough to allow two small holes to be drilled and then secured to the enclosure.

A grille for the W7 is very tricky and will require some creative engineering. The main reason is due to the fact that the diver will travel nearly 1.5" out from the rest position. Some bars across the front that allow the travel would work.

From what I can see and have heard so far is that the EP2500 and the EP4000 are the same amplifier.

Finding banana plugs that fit 10-12 ga. wire is tough on occasion. It is much cheaper to "tin" the bare wire (solder it lightly).

 

[WmAx]

is this enough bracing? if not, do you have any ideas? should i double up the wood on the front? double front baffle(is this what it's called)?

Yes, that is very good. That is exactly what I meant. You could epoxy some steel angle to the rear panel on those wooden cross ribs, though.

i'm going to pickup the driver monday. waiting to get a deal on the amp and eq if possible. if not should i get the ep4000 or is it the same as the 2500?

EP2500 and EP4000 appear to be the same. I would just get EP2500. And you know to get the DCX2496 EQ/Crossover unit for this project, right?

do i need dampening material?

Ideally, yes. High density rockwool as annukai specified or Owens Corning 705 (more expensive, however), which both have teh same effect. You will cover these materials with cloth to prevent the fibers from floating around the inside of the cabinet and possible entering the driver vent.

what conectors do i buy to connect the driver to the wire? soldier?

The driver has push down connectors. No soldering to the driver. But you should ideally 'tin' the wire with solder, or the wire will oxidize over time, thus having a bad connection. Tinning the wire will retard oxidation.

what connectors to connect to amp? to eq?

Assuming you have a standard RCA out from your pre-outs: use a RCA to XLR adapter to the DCX input. Or solder up a custom patch cable. Or, use a convertor box like the ART DTI. This is a transformer convertor box that changes the unbalanced RCA output to true balanced XLR output. You use standard RCA patch cable to the DTI input side and a standard XLR patch cable from the DTI output side to the DCX input. Use standard XLR patch cables to connect DCX outputs to EP2500 inputs. Some people end up with ground loop noise/hum/buzz sounds when connecting unbalanced RCA to blanced XLR pro gear. The DTI box also removes this ground loop problem if it would otherwise occur.

any binding post you recommend? if i cut out a hole for the binding post plate do i need to add material behind it?

Use any binding posts/plates you want. Just make sure they accept 12 AWG.

i want a grill. recommend any? do i make a grill frame? buy one?

JL used to make special grills for the W7 drivers, but I can't seem to find them anymore. They just have these silly bar grill kits now. You would be better off making a custom grill. Just be sure to provide A LOT of clearance; that driver has massive excursion.

-Chris

 

[ParadigmDawg]

I like this guy. He says he wants to build the sub, TLS tells him he can't and he is not ready and about an hour later, he has built one!

Good job my man, good job!!!!!!!!!!!!!!!!!

 

[STRONGBADF1]

I like this guy. He says he wants to build the sub, TLS tells him he can't and he is not ready and about an hour later, he has built one!

Good job my man, good job!!!!!!!!!!!!!!!!!

+1 nice work !

 

[metalrake]

thanks for all the help...it'll will be a bit before i have all the parts...i'm sure i'll have alot more questions then

 

[metalrake]

hello,
i've got everything except the owens dampening material. it's in the mail. i have 4 questions.

1)when i do recieve it, how do i install this inside the speaker with all the bracing in the way. i think you guys said only put it on opposing walls. do i cut it in little peices and cover everything including the sides of the bracing or do i just stuff it in there on top of the bracing? i know to cover it with material when i'm done

2)do any of you know where i could buy some plastic lattice material to make a grill? i was thinking about making a wood frame and covering it with plastic crosses. then covering that with cloth. i was going to flush mount the speaker, but it's sticks out far and if i need access to the screws i won't be able to remove the metal ring. maybe i'll add another front piece and not glue it.

4)i changed the fan in the ep2500, however it's unclear to me which way the air should be blowing. i made it blow in the stock direction(towards the front of the amp). in the thread the fan in positioned in such a way to force air out the back. which way do you reccomend.

4)i'm lost with this amp and eq so far. you said you might be able to give me the settings chris, if i had the t and s?

is this the t and s
Free Air Resonance (Fs): 27.2 Hz
Electrical “Q” (Qes): 0.514
Mechanical “Q” (Qms): 7.807
Total Speaker “Q” (Qts): 0.482
Equivalent Compliance (Vas): 2.33 cu. ft. / 66.0 liters
One-Way, Linear Excursion (Xmax)*: 1.15 in. / 29 mm
Reference Efficiency (no): 0.249%
Efficiency (1W/1m)**: 86.2 dB SPL
Effective Piston Area (Sd): 84 sq. in. / 0.0542 sq. m.
DC Resistance (Re): 2.47 ohm
Nominal Impedance (Znom): 3 ohm
Thermal Power Handling (Pt): 1000W
Driver Displacement: 0.14 cu. ft. / 4.0 liters

this is on the jl audio web site

i'd greatly appreciate it you could help me with that.

i'm almost done, i think. i'll put up some pics when done.
thank you,
sean

 

[WmAx]

hello,


1)when i do recieve it, how do i install this inside the speaker with all the bracing in the way. i think you guys said only put it on opposing walls. do i cut it in little peices and cover everything including the sides of the bracing or do i just stuff it in there on top of the bracing? i know to cover it with material when i'm done

Cut the material into small enough pieces to shove it into the sides and bottom. Cut another piece and place it in the rear. Wrap it with some cloth so that it does not let fibers fly into the interior space and potentially those fibers could go into the driver vent and lodge in the voice coil gap. To install, cut the pieces so that they fit tightly with friction to stay in place - use Liquid Nails or comparable construction caulking adhesive generously on the back of the pieces. When it dries the material will not be able to shift/move.

2)do any of you know where i could buy some plastic lattice material to make a grill? i was thinking about making a wood frame and covering it with plastic crosses. then covering that with cloth. i was going to flush mount the speaker, but it's sticks out far and if i need access to the screws i won't be able to remove the metal ring. maybe i'll add another front piece and not glue it.

There are many ways to make a grill. You just build a deep wood frame and stretch an elastic type black fabric over it and staple the cloth on the back of the frame. That would be very easy. I would probably route a round-over/radius on the outer edges of the grill frame.

4)i changed the fan in the ep2500, however it's unclear to me which way the air should be blowing. i made it blow in the stock direction(towards the front of the amp). in the thread the fan in positioned in such a way to force air out the back. which way do you reccomend.

It will probably be okay either way. But the stock air direction is the safest. The reverse direction allows you to clean the front air intake cloth on the EP2500, where as the stock direction requires you to open the amp to clean the cloth.

4)i'm lost with this amp and eq so far. you said you might be able to give me the settings chris, if i had the t and s?

is this the t and s
Free Air Resonance (Fs): 27.2 Hz
Electrical “Q” (Qes): 0.514
Mechanical “Q” (Qms): 7.807
Total Speaker “Q” (Qts): 0.482
Equivalent Compliance (Vas): 2.33 cu. ft. / 66.0 liters
One-Way, Linear Excursion (Xmax)*: 1.15 in. / 29 mm
Reference Efficiency (no): 0.249%
Efficiency (1W/1m)**: 86.2 dB SPL
Effective Piston Area (Sd): 84 sq. in. / 0.0542 sq. m.
DC Resistance (Re): 2.47 ohm
Nominal Impedance (Znom): 3 ohm
Thermal Power Handling (Pt): 1000W
Driver Displacement: 0.14 cu. ft. / 4.0 liters

What is the net internal volume of your finished cabinet?

-Chris

 

[metalrake]

the speaker box is 18x15x16...the inside dimensions are 16.75 x14.75 x13.75

that's 1.4 x 1.23 x 1.145...comes out to 1.97 cubic feet

minus the driver's Driver Displacement from web site .14 in cubed

comes to 1.83

don't really know how to minus the bracing...forgot my geometry

i think it would be about 1.5 cubic feet

 

[annunaki]

The best thing to do is to plot the room response first before adding any eq. This will tell you baseline response in the room.

Once you have that, you can see where you need to add boost or cut and approximately how much.

You can then plot the response again to see how it worked. In a proper enclosure .707 - .720 Qtc +9.5db boost at 20hz with a "Q" of 1.5, a boost at 30hz of +2db and a "Q" of 2.0, along with a small cut of -1.5db at 42hz and a "Q" of 1.0. gets response flat to about 18hz-19hz in an anechoic environment.

Due to room gain, these numbers will be adjusted though.

 

[metalrake]

acually i think it is 1.6 to 1.65 cubic feet

what does plot the room response mean?

what does boost mean?

 

[metalrake]

i don't have the language down, among other things. sorry

 

[WmAx]

the speaker box is 18x15x16...the inside dimensions are 16.75 x14.75 x13.75

that's 1.4 x 1.23 x 1.145...comes out to 1.97 cubic feet

minus the driver's Driver Displacement from web site .14 in cubed

comes to 1.83

don't really know how to minus the bracing...forgot my geometry

i think it would be about 1.5 cubic feet

Okay, assuming the JL Audio T&S parameters are correct (a BIG 'if' based on the JL W78 units I have measured), you will apply the 1st parametric band at 22Hz, Q=1.4, Gain= +6dB. The 2nd filter is more of a guess, and it depends on the actual inductance of the driver (not specified by JL), which causes a peak in the upper bass response. I am going to guess this driver has about 2mH of inductance, which would mean you need a parametric band at 85Hz, Q=0.7, Gain= -3dB. You can verify/correct/fine tune this filter by actually measuring the acoustic response with no crossover in place and adjusting the band until the response peak is removed.

The above settings will result in free field response approximating -3dB at 29Hz, -6dB at 22Hz. The common gain curve in most rooms will boost the lower frequencies up a bit, resulting in a mostly flat response to 18-20Hz.

Please note that the 6dB positive gain at 22Hz is only possible using a very high power amp such as the EP2500 in bridged mono mode.

-Chris

 

[metalrake]

ok, thank you very much

 

[annunaki]

Plotting room response requires some graphing paper (or Microsoft excel), a cd or audio file with individual frequencies, and an SPL meter.

Plot the reponse by playing a test tone every 3 hz or so starting from around 15hz. Place those values in db on your graph paper (or excel) and you will see the room response before adding eq.

Please see "Build Thread 2" in my signature, page 2 for an example.

 

[annunaki]

acually i think it is 1.6 to 1.65 cubic feet

what does plot the room response mean?

what does boost mean?

Plot room response means to take a baseline measurement of the sub's reponse in the current position prior to adding eq.

Boost means a positive eq value increasing response at a given frequency. Example: +3db at 25hz Q=1.5

The "Q" refers to the width of the gain around the center frequency. The higher the "Q" the closer it gets to increasing just that frequency. The lower it is the more frequencies it will increase around the center frequency.

 

[metalrake]

that makes sence...more complicated then i thought...thanks

when you say "add eq" that means boosting a certain frequency?

 

[metalrake]

or does that mean changing anything on the equilizer

 

[annunaki]

that makes sence...more complicated then i thought...thanks

when you say "add eq" that means boosting a certain frequency?

Add eq would be any sort of boost or cut to smooth response.

 

[metalrake]

as far as the amp...how should the mode switches go
input 1
1) clip limiter ...on
2) low cut filter 50 hz or low cut filter 30 hz...30 hz
3) low cut filter...off
4) stereo/ parallel inputs...parallel inputs
5) stereo/ parallel inputs...parallel inputs
input 2
6) bridge mode...on
7) bridge mode...on
8) low cut filter...off
9) low cut filter 50 hz or low cut filter 30 hz...30 hz
10) clip limiter ...on

this is my best guess from reading the instructions.

it says not to turn off low cut filter, but i think a sub should go under 30 hz and the dcx2496 will handle this???

it says to use both positive outputs from both channels when bridged....does this mean i put the red speaker wire in the input 1 positive speaker output and the black speaker wire in the input 2 positive speaker output. is that it?

also the speaker says it handles 1000 watts...how's it going to handle 2400...or can it handle that amount of power for short periods of time