Apple themed Overnight Sensation MTM

[pcmofo]

Hello everyone. I posted my original concept for a 2.1 computer, desktop speaker system on a few other forums. Since all of the parts I am using came from PE, and many of the people I have been talking to are also in this forum I thought this would be the best place to start my project log.

(Click here to skip to the finished pictures)

Project Goals:

- Build a pair of desktop speakers with an Apple styling to match my computer hardware. (think aluminum, glass, silver, black)

- Build a subwoofer

- Hide/integrate as much of the hardware, wires etc as I can to give a clean finished look.

So my plan is to start with the speakers then move on to the subwoofer. The general plan is to use this amp.
Dayton DTA-100 Class-T Digital Amplifier 50 WPC
to power 2 desktop speakers and this plate amp
Bash 300W Digital Subwoofer Amplifier
to power two sub woofers. Heres the catch. The subwoofers will be built into the underside of the desk. One on each side with the amps in the middle. The amp controls will be rewired and relocated to a recessed plate in the front of the desk allowing easy access to sub levels etc. Here is a picture of what the desk *might* look like inside...



So the desk and the subs are phase 2... phase 1 is the speakers... Once I have finished speakers I can work on the desk and subs.

The design I came up with is very similar to Pauls "Overnight Sensation MTM" design in terms of size, layout, and driver selection. As this is my first home speaker build, I will be using his specs in terms of drivers, box size, and crossovers.

I will be modifying the design slightly. The drivers will be moved up higher in the box to make room for forward facing porting. The overall boxes will have rounded edges on the tops and bottoms, painted silver. The front and back will have black painted plexiglass to give the glossy black appearance. Here is a rendering of what I hope to create (note, the speaker surrounds, tweeters, and porting are shown in dark gray to show contrast with the black plexiglass on the front)



Here is a detail of how the front baffle would be cut to accommodate the plexiglass inlay.



My order has been placed with PE and I'm sure it will be on its way shortly. I'm looking forward to this build.

Here is a list of what I ordered from PE exactly.

NTERNET ORDER DETAILS
-----------------------------------------------------------------------------------------------------------------------

QTY PartNumber Product Price Ext. Price
2 004-10 Dayton DNR-10 10 Ohm 10W Precision Audio Grade Resistor $1.25 $2.50
2 027-340 10uF 100V Non-Polarized Capacitor $0.58 $1.16
2 027-402 Dayton DMPC-0.22 0.22uF 250V Polypropylene Capacitor $0.75 $1.50
4 027-422 Dayton DMPC-4.7 4.7uF 250V Polypropylene Capacitor $2.41 $9.64
2 091-1260 Dayton BAGS-G Banana Speaker Plug 2 Pair $8.50 $17.00
4 091-1245 Dayton BPA-38G HD Binding Post Pair Gold $7.89 $31.56
2 004-1.5 Dayton DNR-1.5 1.5 Ohm 10W Precision Audio Grade Resistor $1.25 $2.50
2 255-022 Jantzen 0.15mH 20 AWG Air Core Inductor $3.27 $6.54
2 255-246 Jantzen 0.90mH 18 AWG Air Core Inductor $7.64 $15.28
4 297-429 HiVi B4N 4" Aluminum Midbass Round Frame $16.83 $67.32
2 264-832 Tang Band W6-1139SI 6-1/2" Subwoofer $49.74 $99.48
2 275-030 Dayton ND20FA-6 3/4" Neodymium Dome Tweeter $7.96 $15.92
1 300-750 Bash 300W Digital Subwoofer Amplifier $149.87 $149.87
2 260-779 Cast Frame #8-32 Speaker Mounting Kit $3.39 $6.78

[the kid]

Re: Apple themed Overnight Sensation MTM

your subs should have fun with your monitor. Pretty creative indeed!

[WWWJD]

Re: Apple themed Overnight Sensation MTM

Did you think about doing a single subwoofer vs. the two in the same air volume? I would think that it would be easier to dig into the lower octaves all things considered. I'm probably wrong.. Either way.. that's gonna be bada$$ when it's done. Now that you've got me thinking on it.. I'd be tempted to do some kind of james bond pop up volume controls.

[Mayhem13]

Re: Apple themed Overnight Sensation MTM

I believe i mentioned on another Forum that using the desk with subs for Laptop use probobly isn't a good idea for the Hard Drive...and the monitor.....magnets being what they are and all. Just a reminder if you didn't see the post.

As for the cabinets for the mains....excellent asthetic design. Do a google search for extruded aluminum/steel tube shapes. You should be able to find some rectangular tubing that can be cut to your depth and then simply 'brush' the exterior with emery cloth for a brushed aluminum finish.

http://www.onlinemetals.com/merchant.cfm?pid=13562&step=4&showunits=inches&id=1008&top_cat=60

[philiparcario]

Re: Apple themed Overnight Sensation MTM

Mayhem13 has a very good point about the sub magnets killing your gear. the subs need to be on the back corners of the desk. You need to make it Impossible to rest anything on the rear two corners of the desk. If you have an upper level to the desk. The two rear corners would have the shelf supports. I just read an internet article about magnets and hard drives. Some IT guy wanted to see how strong a magent was needed to kill the HDD he found time and power played a factor in killing info. Since your magnet will have endless time so to speak putting the subs in the far corner is a good idea.

http://www.drdoak.com/personal/hdd_torture/hdd_torture.htm

this is not the test done that I read last month. basically it was laying a magnet on the hdd for days. simple and it killed off hdds. I think having the subs in the corners shoul dbe good enough

[WWWJD]

Re: Apple themed Overnight Sensation MTM

From the product description: "The compact neodymium motor structure saves valuable enclosure space while also allowing closer-than-normal placement to CRTs."

He can always add some shielding around the magnet on the back of the basket if he feels like there will be a problem. Steel soup cans will work. Leave some gaps so the pole vent can breath around the perimeter and I don't think he'd have any problems. Just gotta keep the flux lines at bay.

[philiparcario]

Re: Apple themed Overnight Sensation MTM

Yeah I tend to think he could make the idea work. proper placing of the two subs with shielding . would do the trick.

[Paul Carmody]

Re: Apple themed Overnight Sensation MTM

From the product description: "The compact neodymium motor structure saves valuable enclosure space while also allowing closer-than-normal placement to CRTs."

He can always add some shielding around the magnet on the back of the basket if he feels like there will be a problem. Steel soup cans will work. Leave some gaps so the pole vent can breath around the perimeter and I don't think he'd have any problems. Just gotta keep the flux lines at bay.

Yeah, I remember asking this question a year or two ago on this board. I tested it out with the monster magnets on some Scan-Speak 18Ws. It made crazy, psychedelic things happen to the CRT, but otherwise I was told not to worry about the HDD. (I'll have to check out that article) But that was a ferrite magnet; the TB subs are neodymium, which clearly does not exhibit the same type of stray magnetic field.

[pcmofo]

Re: Apple themed Overnight Sensation MTM

Thanks for the links and info guys. Like I said, I will be making the speakers first and then the subs. In the process I hope to figure out more details of the desk and how installing the subs might effect all of the gear. I may make a separate sub if I need to. I have to see how the monitor and hard drive will be effected by vibration and magnetic fields. I plan on making a test enclosure for the sub before moving forward. Btw the monitor would be apples LCD which is wrapped completely in aluminum.

Anyone have any suggestions or comments on the speakers before I get started building? Hope to get going in about a week.

[the kid]

Re: Apple themed Overnight Sensation MTM

Could you mount the subs backwards? Use the same cutout location, just mount the sub to the outside of the table. I have seen some car sub boxes like this.

[pcmofo]

Re: Apple themed Overnight Sensation MTM

The parts should be in today. I am almost finished with the digital drawing. I modified the design slightly... The plans call for a 9L volume 6x16x10" using 3/4" MDF. 10" is fairly deep, a bit too deep for a desk considering the distance away from the speakers etc. I dont want them to extend beyond the LCD. I moved the height from 16 to 20" so it matched the LCD height. I then moved the depth from 10" to 8 1/8" which calculates to almost exactly the same 9.0... L volume. Hopefully this will not hinder the performance.

Here is the design with those changes. I built everything piece by piece to show construction. The corners are not rounded and nothing is painted also.

Here you can see the overall box. Tongue and grove slots to hold things together.



Exploded view


Front cutout showing spacing and location of drivers etc


Angle showing 1/8" cutouts for plexiglass and speaker baskets


Rear of front baffle showing slots to join walls and rounding of speaker cutouts


Speakers roughly colored and placed on similar table next to iMac to show approximate scale.


Front on view approximate of actual user view


Thats what I have so far. Still need to create the front and rear plexiglass covers and decide if they will cover the screws/outer frame of the drivers or go around them.

Drivers etc coming today. Hope to build the crossovers and test the setup + amp.

[tomzarbo]

Re: Apple themed Overnight Sensation MTM

That looks awesome. As a suggestion, mock up the dimentions of the desktop and the bottom where your lap will be, just to make sure it's comfortable. Because of the thickness of the desk, it looks like your keyboard may be higher than comfortable, but maybe not.

Oh, and nice drawings! Once you get it worked out, that setup will be nice indeed.

TomZ

[Paul Carmody]

Re: Apple themed Overnight Sensation MTM

Impressive planning. You had the right idea adjusting the depth... internal volume and front baffle width are the key ingredients. All the other dimensions can change as long as you keep those two constant. Should sound exactly the same. Great drawings.

How were you planning on cutting the wood? CNC? I ask because the "tongue-in-groove" may be overkill (although it looks like what you drew are actually called "Splines" in woodworking. There are a zillion ways to join a box together. With this particular project, I just used but joints, and tightly clamped everything for 24 hours or something. Then ran over the edges with a flush-trim bit.

[pcmofo]

Re: Apple themed Overnight Sensation MTM

The desk was a super quick mockup just to get a general idea of colors and placement. I may go with a different desk design ultimately. Right now I just made it blocky like the Apple store desks. Going to go with the cutting board look of many 1-2" pieces glued together for the surface. That way I can have removable panels on the top that pop out but are more hidden into the design of the desk. More on the desk later when I have the speakers built and working on my existing desk (which is sagging due to poor manufacturing and materials) before moving on to the actual desk I will be building.

The slots for joining the wood together are a "best case" scenario. I can do a few things wood working wise. The future father-in-law is the real wood worker. He makes furniture for a living and has all the tools I could ever need, including access to a CNC machine at work... I would love to CNC the pieces but I dont know if I can convert my sketchup files to the correct format for his CNC machine.

I am confidant that he can look at my drawings and dimensions and we can get the important parts right, like position of the drivers and dimensions. We may end up joining things differently with dowels or biscuits etc.

I think I may get the plexiglass laser cut from Pokono. Order 3 pieces for the front and back instead of two so that I can use one as a template to make sure everything fits well.

I just saw the #8 hurricane nuts on PE and I think I will be ordering some of those to mount the drivers with. Now I just need to find some sweet hex bolts that will look nice protruding from the speaker box.

Not shown so much is the rear, I recessed the terminals about 1/4" as I plan on plugging in banana connectors strait into the back.

A question about wires. I want the wires to look sweet. Rounded would be better than flat side by side zip style wire. The runs should be fairly short <5ft each, so about 10ft total, but I cant seem to find wire that looks good. Anyone have a suggestion for twisted pair wire? Gauge recomendation? I was thinking 14-16.

Time to head home and unbox some parts! Might try to wire up the crossovers on some plexi later.

[pcmofo]

Re: Apple themed Overnight Sensation MTM

So all of the parts came today. I decided to build the crossovers on a piece of card board so that I could test the drivers, amp, and general configuration. Here is the bags of parts.



And here is the completed crossover. You will notice it is laid out exactly as the picture in the guide.



I have to say, even without a box I can tell these speakers are going to sound great. They can really move some massive air. The crossover is really doing its job. Disconnecting the tweeter you can hear only mids are going to the 4" drivers. I think I will use plexiglass or a small piece of wood to build the real circuits. I think I can make it a little smaller too. It will most likely be mounted opposite the drivers on the rear wall.

Here is the setup being tested with the amp.


I also tested a single sub and the amp. It comes in a box that holds it perfectly for testing. The back is completly open by the way which means it would be super easy to modify it and install it in the desk.




And last, Here is a picture of the connectors. Both are Dayton gold plated banana,


I stuck a scrap piece of 16ga wire in the center through the hole in the screw post, bent the wires 90deg and tightened it down. I think this will give it a really clean look once I add some "pants" and heat shrink. Any reason not to wire the speakers this way? Also, again, any wire recommendations for twisted 14-16ga wire?