+ Reply to Thread
Page 1 of 11 123 ... LastLast
Results 1 to 15 of 153

Thread: Backyard Box Building - The Build

  1. #1
    Senior Member macaroonie's Avatar
    Join Date
    Jan 2005
    Location
    near Glasgow Scotland
    Posts
    1,587

    Backyard Box Building - The Build

    Hi all at last I am ready to start building my final solution speakers. These will be a kind of L300 clone. This is a project that I have been fermenting for some time ie. about 25 years. I first heard L300s way back in the 70's and the sound signature stuck with me ever since , like an itch you cant scratch.
    I know there are bigger and better monitors but space considerations come into the equation also.
    The purpose of this thread is to create a step by step guide to cabinet building using the minimum of tools and shop facilities, in other words the simplest easiest way that anyone with moderate skills can achieve a good result.
    My project carries some quirks in that I am going to emulate the L300 cabinet but with different dimensions , hence the rounded corners will require more work than a standard rectangular box, however the build methods remain the same for both.
    I would like this thread to remain clear of comments in order that the process is easily followed by anyone who cares to have a go , however I am open to any input along the way.
    To that end please post comments and input on the other thread ' Backyard box building ' and quote the relevant page / post number.
    I will also be calling on the expertise of the gurus at a later stage but that will come along as the build progresses. Here we go-------

  2. #2
    Senior Member macaroonie's Avatar
    Join Date
    Jan 2005
    Location
    near Glasgow Scotland
    Posts
    1,587

    Specification

    This project is to emulate in general the model L300 a JBL classic if ever there was one. To that end I have the following components.

    2 JBL 2235H 15" bass drivers
    2 JBL 2380A Horn throats
    2 B&C DE85ti Mid compression drivers
    2 JBL 2405A Uhf ' slot ' tweeters
    1 JBL M553 electronic crossover network

    Apologies re the B&C compressors but this is Scotland and JBL pro components are not all that thick on the ground and most of the drivers that show up on ebay here have been worked hard. The units I have are brand new and their published response is similar to the JBL 2445 driver. At some time in the future I may make a switch.
    The electronic crossover is here for two reasons. One it cost about the same as making a new passive from scratch and two I am a great believer in the dynamics and control afforded by such an arrangement. It relieves the amplifier of the messy business of handling that nasty passive network.
    For any newbies here there are many referencies to this kind of arrangement in other parts of the forum archive. Stick with this and all will become apparent.

  3. #3
    Senior Member macaroonie's Avatar
    Join Date
    Jan 2005
    Location
    near Glasgow Scotland
    Posts
    1,587

    Design Tools

    As I said this is the lo tech method . No CAD here sir nope.
    Attached Images Attached Images  

  4. #4
    Senior Member macaroonie's Avatar
    Join Date
    Jan 2005
    Location
    near Glasgow Scotland
    Posts
    1,587

    Sketch 1

    I told you this was going to be plain Jane. This is a sketch of the general look of the speaker
    Attached Images Attached Images  

  5. #5
    Senior Member macaroonie's Avatar
    Join Date
    Jan 2005
    Location
    near Glasgow Scotland
    Posts
    1,587

    Sketch 2

    This is the baffle layout. Since I am cramming a quart into a pint pot here the overall size is determined largely by the driver dimensions. I made a bit of a boo boo getting the 2380A throats in that they are somewhat taller than the old conical throat/ lens however the plus is that they extend lower and should integrate better with the bass driver. I will still use the 850 hz crossover point of the original as a starting point although the electronic crossover allows easy tweaking.
    Attached Images Attached Images  

  6. #6
    Senior Member macaroonie's Avatar
    Join Date
    Jan 2005
    Location
    near Glasgow Scotland
    Posts
    1,587

    Sketch 3

    This is a detail of the top corner that mimics the original L300. Standard box builders can ignore this.
    Attached Images Attached Images    

  7. #7
    Senior Member macaroonie's Avatar
    Join Date
    Jan 2005
    Location
    near Glasgow Scotland
    Posts
    1,587

    Sketch 4

    This is a detail of the bottom corner. It does not have to accept the glass as the top does so is much simpler
    Attached Images Attached Images  

  8. #8
    Senior Member macaroonie's Avatar
    Join Date
    Jan 2005
    Location
    near Glasgow Scotland
    Posts
    1,587

    Sketch 5

    General dimensions
    Attached Images Attached Images  

  9. #9
    Senior Member macaroonie's Avatar
    Join Date
    Jan 2005
    Location
    near Glasgow Scotland
    Posts
    1,587

    Tools

    As I said the plan is to use the least tooling possible specifically a Circular saw and a good quality Router. Beyond that only hand tools like a small plane screwdrivers etc and probably a combi drill.
    The circular saw will be used to cut the panels and from there on most of the work will be acomplished with the Router.
    Newbies to this may not be familiar with Routers and should have a look arond the web to get some starter info. I'm sure there are video tutorials available as downloads just to get an intro but as a brief description a Router is a rotary cutter running at high speed with SHARP ! cutting tools of varied shapes. This allows you to cut slots curves and edge profiles. A router is an enormously versatile tool with many uses BUT if not used with care they can at least mess up your work or at worst mess up your fingers. In the main guide bars or roller guides on the cutting tip will keep the tool where it is supposed to be. More on this once I get started.
    Pics are 1 Router 2 close up of a roller guided round off cutter above an edge that it previously cut. In use the cutting tool is spinning at about 20000 rpm. The secret is to not try to cut too much at one time. EASY DOES IT and to do test cuts before you hit your workpiece.
    Attached Images Attached Images   

  10. #10
    Senior Member macaroonie's Avatar
    Join Date
    Jan 2005
    Location
    near Glasgow Scotland
    Posts
    1,587

    Timber

    My preference when building cabinets for speakers is to use a hardwood ply or marine ply. however there seems to be a worldwide shortage of plywood these days so I'll be using 3/4" baltic birch for the baffle and back, suitably braced and 1" for the top bottom and sides. The 1" is necessary to allow the corner radius.
    As has been discussed in the forum before although MDF is a treat to work with from a cutting and machining point of view the dust by product is plain nasty. Balic Birch ply is a joy to work with and is as near to MDF in working characteristics.
    In this case I plan to post veneer the boxes mainly because of the rounded corners , The L300 almost uniquely has the veneer grain running horizontally.

  11. #11
    Senior Member macaroonie's Avatar
    Join Date
    Jan 2005
    Location
    near Glasgow Scotland
    Posts
    1,587

    Timber cutting

    Sheets of plywood generally come as 8ft x 4ft. Because of this you have to map out a cutting plan in order to get the most from your sheet and to avoid unnecessary cuts. If you have a look at the sizes of commercial boxes you will be able to spot dimensions that are just less than a subdivision of a sheet. ie. 23.5 " gives you 2 panels across the 48" sheet.
    Since I am using two different thicknesses of ply I am not under any real pressure for usage although the 1" sheet does have to give me 4 sides and 2 tops and 2 bottoms. The depth of the cabinet is to be 15.75 ( a small change from the original sketch 5 above ) This is to give me 3 planks as it were 8ft x 15.75". This then gives me all the pieces and leaves a decent chunk for future use. If you try to do this across the sheet you land up with a lot of silly offcuts.
    It is worth spending a little time with a pencil and paper to figure out a cutting plan.

  12. #12
    Senior Member macaroonie's Avatar
    Join Date
    Jan 2005
    Location
    near Glasgow Scotland
    Posts
    1,587
    I had intended to start cutting today but we have RAIN.

  13. #13
    Senior Member macaroonie's Avatar
    Join Date
    Jan 2005
    Location
    near Glasgow Scotland
    Posts
    1,587

    Update

    Well we have been having the worst spell of rainy weather of late and any time I get some spare time , well down it comes.
    As it happens the work I have been doing lately has allowed me to snatch some pics of routing in action.
    What we have here is a kitchen island worktop in solid oak block. It is getting a cutout to take an undermounted drainer. The first picture shows the router with a trepanning bar, basically a rod that has a pointed pivot in the center.
    The wingnuts on the router base allow infinite adjustment. You will see the relevence to loudspeaker cutouts here.
    I am cutting wood away on the underside of the panel to allow the drainer to locate. This diameter is larger than the cutout as seen from the top so the sheet is flipped over and the final cutting is done from the top but at a lesser diameter.
    There is a small pilot hole drilled right through at the center that gives you center from both sides.
    The closeup of the cutter shows a straight flute ie' parallel type. The cuts are fairly gentle approx 1/16" at a time. Any more than that and we have screaming and burning.
    The last cut from the top before the block is completely removed is a fractionly larger diameter ( no more than a whisker ) to give a clean up on the walls of the cut. This is done very gently in this case because I don't want any scorching on the walls of the cutout.
    As you can see in the finished picture I have chased around the top edge with a 45deg guided cutter ( has a roller bearing on it ) .
    This is more or less the same procedure that we would use in making a cutout for a speaker where the driver is recessed into the baffle.
    We had a total downpour last night here but it seems to have cleared the skies somewhat, so we might get to chop up some plywood tomorrow.
    This is going to be done in my backyard, as it says on the tin.
    Attached Images Attached Images    

  14. #14
    Senior Member macaroonie's Avatar
    Join Date
    Jan 2005
    Location
    near Glasgow Scotland
    Posts
    1,587
    OOps the pics went up in the wrong order, no matter.
    You might have noticed in the closeup pic that the wood is tearing slightly at the edge. This can happen and in this case it occurred because the wood is oiled as it comes from the factory.
    That was a brand new cutter. oak can be a bit chippy in any case

  15. #15
    Senior Member macaroonie's Avatar
    Join Date
    Jan 2005
    Location
    near Glasgow Scotland
    Posts
    1,587

    Progress at last

    A fine sunny day at last so we can get some slicing done.
    Backyard as promised two 2x4s to work on. Crude ? yes !
    Attached Images Attached Images  

+ Reply to Thread

Thread Information

Users Browsing this Thread

There are currently 1 users browsing this thread. (0 members and 1 guests)

Similar Threads

  1. Building new sub/mid box
    By maxwedge in forum Lansing Product DIY Forum
    Replies: 74
    Last Post: 12-27-2008, 12:12 PM
  2. D130 / 075 / N2400 Custom Box Job
    By rrwalkertr in forum Lansing Product DIY Forum
    Replies: 38
    Last Post: 04-06-2008, 06:42 PM
  3. Backyard box building.
    By macaroonie in forum Lansing Product DIY Forum
    Replies: 90
    Last Post: 12-14-2007, 11:12 AM
  4. Time to build a box: Material?
    By PaulB in forum General Audio Discussion
    Replies: 14
    Last Post: 10-20-2006, 04:38 AM
  5. plans to build a box
    By Klaus in forum Lansing Product Technical Help
    Replies: 16
    Last Post: 09-06-2003, 11:24 AM

Posting Permissions

  • You may not post new threads
  • You may not post replies
  • You may not post attachments
  • You may not edit your posts