Lab 12 Based Offset Driver - Mass Loaded - Transmission Line (OD-ML-TL) Design by Bj

[USRFobiwan]

MSh84, it is not a difficult build. You don't need a CNC cutter. But since you know how CNC works it is easy to put in the dimensions into the CNC, cad or vector program.

 

[tb46]

Hi USRFobiwan,

I send msh84 the drawing, so now we'll wait what he comes up with. It's basically just the principle, and can be modified to suit different form factors, etc....

Regards,

 

[USRFobiwan]

I simmed a bunch (26) of 'car' subwoofers bases on the HR input from post #268 (epic 12 sim). The below list seems to be suitable for this design with relative flat response from 20-120Hz range.

From low to medium price range:

Phoenix Gold RX112
Ground Zero GZTW30TX
JBL-GT5-12
ESX SX1240
Crunch MXB124
Infinity Kappa 120,9w
GroundZero GZUQ 12SQX
Hifonics MXS12D2
Phoenix Gold SX112D4

 

[msh84]

Hi thanks guys for your reply it is good to see that community is awake ad happy to help even on such a old thread.

I want to cut it with CNC just because I can, beside I wound not trust myself with circular saw to make perfect straight line or exact 90 deg corner. If I design it right then I can cut it precisely and it should go up like IKEA furniture (hehe).

I just wonder what could go wrong as I don't have that much experience with wood. We mainly routing dibond and acrylic at my workplace.

In terms of drivers Thank you for you advise but I stuck with 2 LAB12 drivers that I bought new never used for good price. They seating under my desk for last 2 months.

I may build one cabinet and if it works build another one and put it on top as I dot have a lot of space. Unless I can fit it behind sofa between sofa and wall but I am not sure if I can gain anything.

Anyway thank you for your time.

I will post pictures once I start doing anything and I will start new thread and post link hear as well.

 

[tb46]

Hi msh84,

Depending on your CNC capabilities it may be possible to insert the duct boards into shallow grooves, this makes for a much stronger box, and makes duct sealing easier.

We always love pictures.

Regards,

 

[GM]

I just wonder what could go wrong as I don't have that much experience with wood. We mainly routing dibond and acrylic at my workplace.

So make them out of acrylic , just add a second layer at key points on the exterior to sufficiently stiffen it unless you use 1" or thicker.

GM

 

[Etocynned]

ooooohhhhh,,,, shiny!

 

[USRFobiwan]

CNC Birch plywood can be hard on the tools. Take a look here if you having trouble cutting Birch. There are some great tips there that helped me doing some test runs on my still in building progress CNS router.

On my sawtable I have to resharpen the blade after about 20 sheets.

 

[msh84]

So make them out of acrylic , just add a second layer at key points on the exterior to sufficiently stiffen it unless you use 1" or thicker.

GM

Wow that would be heavy and expensive

Uk cost 3m x 2m 10mm black - £396
3m x 2m 20mm Clear (our supplier dot have colours above 10mm thickens) -£652

I am willing to give away my account number if you guys want to sponsor project so we can find out if acrylic is suitable for sub woofer manufacturing .

1.5m x 2m of 20mm clear acrylic is heavy enough for 2 people to carry. It is so heavy that I would avoid handling full size sheet at 3m x 2m.

 

[msh84]

TB46 - Part of my plan is to do shallow groves for easy position of duck port parts.
My only problem is pockets I will grove they will have rounded corners (as I will cut with 6mm round bit). Other elements they will have square edge but I guess that I can always trim a little bit of by hand.

USRFobiwan - Thanks for Link very useful read

GM - 20mm Clear acrylic 3m x 2m in uk is £652 and it is very heavy but I am wiling to give away my account number if some one is willing to sponsor this project in name o science

Any thoughts on building this out of MDF or is it not recommended?

If MDF is ok option then what is recommended thickens?

Any thoughts on using 18mm Hardwood Throughout Plywood?
This is what my local supplier have:

https://www.alsfordtimber.com/sheet...-and-en314-2-e1-18x2440x1220mm-hdply18e1.html

I ma not really concern about finish as i will paint or stain cabinets.

 

[tb46]

Hi msh84,

Post #350: "...I will cut with 6mm round bit..."

Is that a 6mm Dia. bit w/ 3mm radiused corners, or a bit w/ 6mm radius bottom edge? That would make a difference in how deep you have to go to get the the full groove width. Generally I would recommend using a square edged bit.

As to the wood I recommend baltic birch plywood 3/4"nom. (23/32" or 18.3mm). Make sure that whatever you use is void free. MDF will do, particularly for a first run.

Regards,

 

[msh84]

So I finally start building my subwoofer. I cut all my MDF and started sanding and priming.

I will post some pictures later one. I have quick question I am wonder if some one is able to help me. What Should I use for stuffing and where I can get it.

I just realised that I need to stuff cabinet before I glue everything together.

I would greatly appreciate some help or pointing me in right direction (without searching whole forum as I am on very tight deadline)

Kind regards

m.84

 

[tb46]

Hi msh84,

As to stuffing/filling:

- Polyfill-as in pillow stuffing-should do the job. (Somebody noted that some of Ikea's pillows are the cheapest source for polyfill. Just don't know where I read that?)

- Take another look @ Post #270, the drawing does contain a note on filling.

- You can always add filling through the woofer opening, but lining-as shown by the jessman-with a thin layer of felt is only possible if you have access to the path.

- A layer of cheese cloth over the back of the driver would keep stuffing away from the cone...

Regards,