(Possibly quite slow) Davids for home studio

[Dan_S]

Dear all,

It's been a few years since I've built anything of Bill's, the last two being a Tuba 18 and Omni 15.

Since then, I've built two Bass Guitars using the skills I'd started out with on the BFM projects!

But, now I'm back, with power tools of my own, and I'm looking forward to this project!

My first question is: At the Lowe's near me (less than a mile away), they have 4x8' plywood (1/2 Pine sheathing, 1/2" Fir sanded, or 15/32 Fir sheathing), but nothing in the 5x5' size recommended by the plans. Which of the above would you recommend, and can I get away with just one 4x8' sheet?

I've seen that to be the case with other BFM designs, so I'm hopeful!

Thanks in advance, and I'm looking forward to getting started!

Dan

[Bruce Weldy]

Forget Lowes, Home Depot, or any other big box store.

Get on Google and look for lumber suppliers. These are the guys that sell to the cabinet shops who use baltic birch for drawers, etc.

If that doesn't find a supplier, call some cabinet makers and ask them where they buy their baltic birch. And make sure you stipulate baltic birch - not just birch....two different things.

You shouldn't have any problem finding 5x5 baltic birch if you spend a little time looking in the right places.

[Bruce Weldy]

Here's a link to a supplier that says they have baltic birch...

http://www.woodfinder.com/listings/013727.php

Scroll down to the Wood and Wood Products section....it's at the bottom.

[Dan_S]

Thanks very much Bruce! I'll get in touch with them to see what they have.

I should probably defy my own convention by getting the speakers first, so that I don't have to wait for test fitting on the baffles

[bassmonster]

Cool! Haven't seen many David builds here.

[Charles Warwick]

If the Lowes near you is like the on here they should carry this:
http://www.lowes.com/pd_170770-49114-LB ... Id=3015484

Arauco is a recommended ply for build BFM cabs. It's not as durable as baltic birch, but is much cheaper and the cab ends up being much lighter.

[Dan_S]

Interesting Charles, thanks for the tip!

For this project it'll probably be worth it, seeing as I have more time than money, even though I don't have much of that!

The Davids are going to move very little once they have been correctly placed, so road-grade durability isn't really necessary

[subharmonic]

Interesting Charles, thanks for the tip!

For this project it'll probably be worth it, seeing as I have more time than money, even though I don't have much of that!

The Davids are going to move very little once they have been correctly placed, so road-grade durability isn't really necessary

I was going to build a pair of Davids...until I priced out components.....please excuse me if this comes off wrong but wood is the cheapest part of the build....What are the driver, and x-over part of your plan?

Also iirc you can do MDF on these if desired, the pine linked I have built with a lot and you usually are fighting warps and probably won't look the best stained but painted is fine.

Looking forward to your build and review.

[Dan_S]

Ok, so I gave in and decided to take the MDF route. Definitely not the best option, but acquiring it was within my current budget. I used some free, but warped MDF for my Omni15, and so I had the fun of clamping it straight whilst the glue was setting in a more humid environment. Thankfully, Colorado's pretty dry at the moment, and I now have a flat garage floor where I can lay the pieces for storage.

I bought it at Lowes, and had the lumber yard cut it to the right widths. Note, there's a discrepancy in the plans where it says to cut everything to 14" wide, yet the side panels are 14.5" wide. Good thing I noticed beforehand!

So far today I've managed to cut the sides for the first speaker (I've bought enough for a stereo pair). For some reason, all of the measuring, re-measuring, setting a guide board and checking that 3 times provided me with a cut that wasn't square. Fortunately it's only slight, and I compensated so that both sides mirrored each other. I'll make a note here for this so that I don't line any panels up to the non-square edge, and then cut or rout it away once the panels are in.

Now it's time to order the MCM 55-2421s, and then tomorrow get the side panels for the second speaker cut. For me it's usually easier to things simultaneously, as I can repeat the same step. The key is staying organised with which wood goes to which speaker, but I intend to be clear with my labelling, something which has tripped me up before.

[Bas Gooiker]

I was going to build a pair of Davids...until I priced out components.....please excuse me if this comes off wrong but wood is the cheapest part of the build....What are the driver, and x-over part of your plan?

Also iirc you can do MDF on these if desired, the pine linked I have built with a lot and you usually are fighting warps and probably won't look the best stained but painted.

I have a pile of mdf panels precut in the corner of the shed. They will become 2 piano black Davids someday, but sinds its 200 euro for the 2 Tang Bands alone here in Europe, and then the rest of the speakers & crossover parts they are on hold for now.

Long story short: +1 on the mdf. Cheap and easyer to apply hifi finishes becouse of the smooth surface.

[Dan_S]

The MCM 55-2421s arrived yesterday - it certainly makes a difference when you ship speakers from Ohio to Colorado, rather than to England! These were in 'brand new' condition (whereas my previous pair had obviously had a rough ride across the atlantic!), though I've not had a chance to start running them in yet.

I've taken some measurements this evening, and it looks like the diameter of the rubber ring that will ultimately sandwich between the basket and the baffle is 7.25". The last time I cut the holes I had an adjustable hole cutter (a rather dangerous and unweildy thing that attached to a drill, making even more unnerving to use!), but for the moment it's just me and the jigsaw.

Given that the ideal method of cutting the hole for the driver is to create an angle (for the allowance of extra wood for the hurricane nuts to sit in), is there a good way of circle cutting using just a jigsaw set at a 45 degree angle? 7.25" seems quite tight, but I may be wrong.

I'm going to try to get some work done on the pair this weekend. Hopefully it works out that way!

[Tom Smit]

Given that the ideal method of cutting the hole for the driver is to create an angle (for the allowance of extra wood for the hurricane nuts to sit in), is there a good way of circle cutting using just a jigsaw set at a 45 degree angle? 7.25" seems quite tight, but I may be wrong.

I'm going to try to get some work done on the pair this weekend. Hopefully it works out that way!

If you had a router, you could make the hole smaller by 1", and then use a v-bit or even a round-over to get to the correct gasket diameter. You would have to use a template underneath (with handheld...overtop on table) to guide the bit to the correct diameter.
If it's a jigsaw, lay it over at 45 degrees and make it follow the line for the 7 1/4". Make sure that the taper goes into the hole, thus ending with a smaller hole on the other side of the baffle.

[Dan_S]

Thanks for the idea Tom! Unfortunately, I don't have possession of my router at the moment, so I've had to do some improvising this weekend!

I haven't managed to get too much done - being in a new house with a wife who's been ill all week and a 9 and a half month old baby that's into everything has left me with plenty of things to do.

Today I cut out the infamous panel 1, and to be honest I think it's the only time I've used a jigsaw at a full 45 degree angle. I was surprised how well it cut though!

To get to the golden number of 58 degrees on the angled edge, I started with the 45 degree cut, and then used an angle measure to add 13 degrees to each side of the board. Then I used a combination of a flat rasp and a flat file to work down to those lines. In hindsight, the easy way would have been to use the two measurements given in the plans and initially worked to that, but I was pleasantly surprised to find my 'dead reckoning' on the angle matched these measurements.

With the angled circle for the speaker, I drew the circle out using the old naill-string-pencil technique, and then doing a freehand cut with the jigsaw. It was by no means perfect (you'll see once I've uploaded the pictures), but placing the driver on the board and extending the cone didn't show any points where the surround would hit the baffle. To be on the safe side, I did file certain areas away, but there was still enough wood for a good seal, and for the hurricane nuts.

The hurricane nuts are a pain. Firstly, the set I've bought are $3 a piece, which seems hideously expensive! Secondly, I didn't have any drill bits big enough to allow them to fit. I went to Lowe's and bought a set of spade bits which will bode well for the future, but found that I could ream the holes out with the round file that I have.

Thirdly, using a clamp to press them into the MDF DOES NOT WORK. I have found I had to hammer them in to get them to go anywhere. My wife had to stop me at 9pm because I didn't realise what time it was, and I'd probably be disturbing our neighbours.

Oh well. My intent was to have panel 1 glued to the side tonight, but it looks like that failed. I'll be working on it tomorrow night though.

I'll also get some photographs online soon, so that people can actually see I'm doing something

[Tom Smit]

Patience, laddie, patience!
I know full well what it's like, what with the chillun' sleeping, and neighbors, and household chores, etc etc. But, eventually, you'll be looking and listening with pride, to what you have built.

[Dan_S]

Very true - it's just a turbulent time as we're still trying to organise the house now that we've moved in. It never seems to end!

It also looks like my "smartphone" is quite stupid, as it takes pictures that can't be viewed - BUT, I have a very clever "camera" that takes pictures that can!

So, today my progress is to hammer in the remainder of the hurricane nuts (I applied epoxy to them too, to stop them from spinning), and glued panel 1 to the side. Here it is!



One thing I must say is that the PL glue is great. In my previous projects, the glue I used was more like putty, whereas this is slightly thinner, smoother, easier to work, and easier to create a sealed join. It comes off the fingers easily too!

Looking forward to panel 2!