Electronics Beginning of some DIY speakers ***DONE!***

***THOSE WHO ARE NEW TO THE THREAD, ALL UPDATES ARE POSTED IN THE FIRST POST TO MAKE YOUR LIFE EASIER. FOR SUBSCRIBERS, THE UPDATES ARE ADDED IN SUBSEQUENT POSTS (IE, SCROLL TO THE LAST PAGE)***

For my wood shop summative, I've decided to make some DIY bookshelf speakers. Normally, MDF would be use, but to cut that during class time would require having respirators and goggles for all 24 guys. So no MDF. BUT I have scrounged up some 3/4" Baltic Birch/Russian Plywood as a substitute, which will get here on Monday. I plan to duplicate a set of Zaph's Bargain Mini's, although with a few tweaks of my own.

1) Recess the baffle into the 4 sides
2) Do a 3/4" roundover on the front of the sides
3) Have a recessed back

Preliminary side sketch:



Front drawing (from Zaph's page):



Baffle detail (also from Zaph's page):



Dimensions are 9 1/4" deep, 10" tall, and 6 1/4" wide

Crossover Components:
-2x Bennic wirewound 4ohm resistors
-2x Bennic wirewound 5ohm resistors
-2x 10uF Solen/SCR/Bennic/Clarity Caps Poly capacitors
-2x 2.7uF Solen/SCR/Bennic/Clarity Caps Poly capacitors
-2x 3.3uF Solen/SCR/Bennic/Clarity Caps Poly capacitors
-2x 1.5mH Solen/other brand 18-20ga inductors
-2x 0.25mH (or close to) Solen/other brand 18-20ga inductors
-2x 0.1mH Solen/other brand 18-20ga inductors
-Speaker wire as ICs between the Xover & woofers/tweeters/binding posts
-63/37 0.20-0.32" dia. solder

Vendors: Solen, Madisound, PartsExpress, any other reliable DIY place

Cabinet Parts:
-5' x 5' 3/4" Baltic Birch/Russian Plywood (this is the size it comes in, you only need half of that for a pair, with lots to spare)
-1" dia. x 4" Port tube (I couldn't find any 1" dia. PVC tubing at Home Depot or Rona, so I had to buy special port tubes)
-2x MCM 4'' Shielded Aluminum Cone Woofer (Part #: 55-1853)
***Remember to get the source code on the flyer (here), as it'll get you a discount (only if the woofer is on sale)***
-2x Aurasound NT1-204-8D 3/4" Titanium Dome Tweeter
***DO NOT TOUCH THE DOME***
It is out of stock with a lead time of at least 4 weeks, a substitute (same size & mounting method), BUT IT IS NOT RECOMMENDED, is below
-2x Dayton ND20FB-4 Rear-Mount 3/4" Neodymium Dome Tweeter
-1/2" Sonic Barrier Dampening
-1 1/4" Sonic Barrier Dampening
OR
-1/2" Chopped foam carpet padding doubled (or tripled) up
***To judge whether chopped foam is good or not, hold it up to the light. There shouldn't be many pinpricks of light shining through. This type of material is pretty much the only cost-effective damping material for speakers. It's really not that bad.***
-5/16" OR 1/4", 1 1/2" long socket cap screws (black)
-5/16" OR 1/4" Tee nuts
-4x Binding posts
-Various sizes of heatshrink

LOG

March 10, 2008
-Ordered parts

March 15, 2008
-Some parts arrived :





March 17, 2008
-My plywood arrived, except it was the wrong thickness...

March 18, 2008
-Some crappy pics of my workspace:





March 19, 2008
-PE order arrived, along with my wood!


Hmmm, whats in the PE box?...


Some books and...


MY TWEETERS...


Close-up of the protective cap & tweeter


Along with my 18mm (sigh...they don't make it exactly 3/4") Baltic Birch


Dramatic angle shot showing all 13 plies



March 26, 2008
-My Mini-RCA IC parts arrived (Canare Star-Quad, Switchcraft connectors)







March 27, 2008
-IC done (Canare StarQuad, Switchcraft connectors), Mini-RCA:









March 28, 2008
-My woofers arrived and I began cutting the wood to width:







March 29, 2008
-The last of my parts arrived, some perfect lay inductors and wirewound resistors from Solen
-Soldered all the wires to the woofer and tweeter, all preliminary work done, have to wait until enclosure is done


OOOH A BOX! What's inside it????


Parts


More parts...


More parts....




Speaker and tweeter tabs are a b!tch to solder and thread stranded wire through...I HATE THEM ALL.

Some pics of my home workshop (ie, the dining room table and kitchen counter):





April Fool's Day
-OK, next update. First up, some better pictures of my workshop, and then some pics of the completed side and tip panels. Will get a new soldering iron tomorrow, wish me luck











Brendan

 

Do you have a tuned frequency for the Xover in mind. Small speakers won't do real bass well. Tuned port enclosure? should be fun to watch.
John

 

Yes, the "crossover is an acoustic 4th order at 3kHz". Has been tweaked a bit to compensate for the different tweeter.

 

Interesting

 

id been looking at doin this for quite some time.
i will be watching

 

I would go for chipboard rather than plywood if you can't get or use MDF. Chipboard is better at absorbing stray waves than ply is.

 

Interesting, I'm watching...

 

sweet! got a schematic for the x-over?

 

Chipboard (or rather particle board) is surpassed by Russian ply and MDF. I will have foam dampening inside the cabinet to absorb the waves.

@ jakenbake, not the most recent revision, as it's not proven yet to work seamlessly with the new tweeter, the old one is below (which works flawlessly with the Aura NT1, IF you can find them):



Brendan

 

ARRG, have to wait till tomorrow for the plywood to come...sigh. In the meantime, enjoy some crappy pics of my workspace:





Brendan

 

PE order arrived, along with my wood!


Hmmm, whats in the PE box?...


Some books and...


MY TWEETERS...


Close-up of the protective cap & tweeter


Along with my 18mm (sigh...they don't make it exactly 3/4") Baltic Birch


Dramatic angle shot showing all 13 plies



Brendan

 

Chipboard is a horrible material for speaker enclosure construction. Of the readily available materials out there MDF/HDF and Marine ply (baltic birch) are by far the best to use.

That shop should be able to handle the MDF dust just fine with all that air filtration, as long as the filters are clean. However, you already have the ply and that will work just fine as well.

Instead of using carpet foam get some polyfill from a local store such as Wal-Mart. They will have it in big rolls in the fabric section. It's very cheap and works very well.

 

I'm getting the carpet padding for free, so I guess I'll go with it. BTW, wassup fellow canadian?

Brendan

 

you gonna start building this weekend?

 

At school, so during the week

 

What are your plans for the finish? Going with a veneer or paint?

 

No veneer, as the birch looks really good on its own. Maybe some Varathane for the sides and some matte black paint for the baffle.

Brendan

 

My Mini-RCA IC parts arrived (Canare Star-Quad, Switchcraft connectors)







Brendan

 

IC done (Canare StarQuad, Switchcraft connectors), Mini-RCA:









Comments please!

Brendan

 

That looks like Dynamics homework under there. Ew.