2x Jack 112, Hamilton, NZ

[JonoSkip]

Hi All
This is my first BFM build, and my first woodworking project in a long time, having built a coffee table some 17 years ago with a lot of help. I'm building 2x Jack 112 with no tweeters, for my bass playing habit. I hope that by posting the build here I can get some help and advice as I go and maybe encourage others who are sitting on the fence. I am not an expert, but I have read the plans quite a few times. I will probably still ask some dumb questions but that is what I am here for.

I have borrowed a lot of tools and am building the Jacks in my garage. The photo below shows the garage during the build at about the messiest it gets as I have to fit a car in at night and the laundry is out of shot to the right. I also like to be tidy

I built a cutting table to use when cutting the plywood down to more manageable sizes as per Bills suggestion (not quite the same) and it has been great (on the floor in the photo above). I scavenged the wood for it from a building site over the fence. It was discarded after being used as boxing for concrete foundations so I had to brush what little concrete was still attached off with a wire brush but it came up clean with some effort.

I'm using 12mm Italian Poplar for the build and this next photo shows my first cut, using a circular saw with a brand new 184mm, 60 tooth blade and a level as a fence/guide. That cut piece is for the bottom (lower right corner of the photo) and a side (top Left corner of the photo), the vent ducts and throat reflectors to come from the middle section. I marked/cut it like that cos I figured at least two parts would have a square corner!

Moving right along, I have marked up the bottom as per the plans, made more cuts, marked up the baffle and cut it out using a jig saw.

[JonoSkip]

I then cut the vent ducts, throat reflectors and throat panels, making sure to get the angles in the right places. That's where reading the plans pays off because it just dawned on my one day after reading the throat panel section which way round they went. Also having the bottom marked up is very useful to help visualise where things go.

Finally I get to glue something! Here I go gluing a vent duct to a throat panel.

I'm using Gorilla Grip Express 1 Hour Cure after finding that recommended in a post in the Supplier, Tips etc section. Premium PL is not available here in NZ but this stuff does the job. After reading the instructions it says that "..the glue cures under the influence of humidity and slight moistening of the substrates improves curing rate and gap filling..." and will "...foam up to penetrate the bond cavity." Just what I want so I used a wet cloth to moisten the joint lines on each part and let rip with the glue. Now I was expecting a messy time with the glue so I laid down plastic sheet on my bench, used grease proof paper over clamps and guides and was wearing nitrile gloves. But no dramas, clean and tidy, the glue went only where it was supposed to. I'm still careful though. Here's a close-up of the joint:

I then glued, screwed and clamped another throat panel on and then the second throat panel doing one joint at a time as I didn't have enough clamps to do both joints at once (will soon fix that) and it worked out OK.

[JonoSkip]

Next, I glued, screwed and clamped the throat assembly to the baffle.

I then glued (only) the throat reflectors in place using a trick from another build thread (thanks NeilD321!), blocks with 45 degree notches to sit over the baffle and throat for the clamp to clamp to. The screw in the picture is so I can hold the part as I place it.

So that is where I'm up to now build wise. I have cut the horn braces (no pic yet sorry) and haven't worried about lightening holes as this poplar is pretty light by itself.

I have marked out the driver spacer as shown below, with a phase plug extension in the middle of it, more to the left of the panel and the back braces in the middle. I will use the top of the panel for the back flanges/frame for the back panel.

You may notice that I haven't made the driver spacer a ring like the plans describe. I have marked it as a 14" square centered around the 10 & 7/8" circle. I'm thinking that the 14" square will be easier to center on the baffle since the baffle is 14" square also in the middle. I figure there is not much lost in total volume by doing this, am I wrong? There is still time to revert to a smaller 13" square as I have seen in other builds or even the 13" diameter circle as per the plans but apart from looking cool, it's just another circle I have to carefully cut with my jig saw to ensure a good looking part that won't be seen.

Advice please and thanks in advance

[JonoSkip]

Forgot to mention that I am using the Eminence Deltalite II 2512 drivers for this build and as such am using the long vent ducts. Also, the phase plug is 5" diameter since I am not using the NSD compression driver.

[Jon Barnhardt]

looks good. The 14" vs 13" square shouldn't matter as long as you aren't covering up the air ducts on the baffle. Mostly a weight savings thing.

[Alien]

I will probably still ask some dumb questions but that is what I am here for.

There are no dumb questions, only people too dumb to realise they should be asking questions.

[bassmonster]

Looking good, clean build.

[el_ingeniero]

Looking good, clean build.

Indeed. The T39s I'm building are full of glue splashes, footprints and general grime.

[JonoSkip]

ooks good. The 14" vs 13" square shouldn't matter as long as you aren't covering up the air ducts on the baffle. Mostly a weight savings thing.

Thanks Jon, that's what I thought.

Thanks to the others who have made comments also.

Tonight I cut out the driver spacer and took a phase plug extension from the centre waste (not shown). It didn't turn out not too bad using only a jig saw IMHO.

Placed it on the baffle assembly to see how it looked. The fit is good, with the circle just cutting the edge of the inner baffle cutouts as shown in the plans. I even made the circle diameter a little bigger after measuring my drivers, 282mm instead of 276mm (10 7/8").

Apologies if the photos aren't great, I took them at night on my phone.

Clean up and that was it for tonight, sleeping children to think of. I hope to attach everything else that is left to the baffle assembly this weekend and also start cutting the parts for the second Jack, ready for gluing next week.

[JonoSkip]

Ok, a bit of a delay in the posts but as threatened, last weekend I attached the braces along with the driver spacer and phase plug extensions to the baffle assembly. I know that is a little out of order as per the plans but I figured it was easier to clamp all that on now rather than doing it with all the sides on. Gluing and clamping the braces, one at a time, same deal for each:

Pic showing both braces attached:

Next ones show the assembly after the driver spacer and phase plug extensions were added. I did these both/all at the same time which was easy with all clamps called into action (pretty boring so no pic). Also the pics are after all the glue has been removed and a good sanding:

The driver spacer looks rounder in real life, honest!

The PP Extns are only glued on, no screws.

Since then I have started cutting out the parts for the second J112 and have almost cut all the throat assembly parts, just the throat reflectors to do. Pics to come this weekend as it has been a bit dim in the shed this week (builder included ).

My holiday break is over so I've only been in the shed after work, after the kids are in bed. That only leads to trying to rush things, leads to mistakes. Nothing to drastic, just cutting parts too big. Borrowed a friends plane and got them down to the right size pretty quickly. I did start a cut for one of the sides and put the saw fence on the wrong side of the cut line I only went about 10mm into the panel so it can be recovered, cutting the back panel out of it and I should get the braces out of it too.

Lesson learned, don't rush, think more.

[JonoSkip]

It's been awhile between posts and a lot has happened with the build so it's time for an update. After getting the first Jack to the point of having the baffle, throat,braces, driver spacer and phase plug extensions all assembled I started work on cutting and assembling the second Jack to the same point. Baffle and throat parts cut:

Gluing up the throat panels and vent ducts:

Gluing baffle and throat together:

And through the magic of television, both together at the same point with some bog filling up some holes:

After doing the first one, this second one went a lot quicker and I did a couple of things slightly differently but nothing memorable, just getting used to using the tools really.

I had an idea in my head about painting the throat, inside top and bottom red and I also thought it would be hard to get the vents painted after they were attached to the tops and bottoms. So I decided to paint them before putting them together. I masked off all the joint lines and sprayed them with a primer:

Happy with that I then started spraying the red. Not happy any more.
After many coats of a Ruby red, still seeing dark grey primer, not getting any coverage, getting paint runs because I was angry and spraying too heavily I scraped and sanded it smooth and sprayed it all mat black. No pics of the red sorry, just too damn angry to operate a camera. I'm happy with the black now and have moved on.

[JonoSkip]

Bottom and throat being put together, the second one needed a bit of encouragement to get straight:

So now I'm attaching the mouth panels and have only one more to put on:

I'm using the tape to keep the glue off the paint and make the clean up easier, I've found it works well for me.

I'm now busy spraying the tops black as I hadn't done that with the others. I'm getting the sides ready and so looking at cutting the holes for the handles I'm using. They are the flush mount Penn spring handle from Leland which are probably only 8mm deep. Rather then use a router to recess out the hole (borrowed router and don't have a bit with a top mount bearing for a template), my intention is to cut the hole out with a jigsaw and glue and screw a cover board over the back to keep it airtight. Anyone else do it that way?

[The Big M]

Lookin' good, you're going to love these!

[Grant Bunter]

Keep up the nice work there Jono

[JonoSkip]

Keep up the nice work there Jono

Lookin' good, you're going to love these!

Thanks guys, your comments are appreciated.