Leon's new speaker build

[L J T]

For this build, I wanted a compact two way monitor.

It had to be different though.

I was sitting at home and thinking of how to make a curved cabinet. I had seen many ideas on the net and one that stood out involved the use of separate panels formed and stacked to create an enclosure.

Here's how it all began

The shape is basically an ellipse that has it's shortest side truncated to form a flat side.

I made an accurate template and the cutting began.

All 48 pieces of them

I made a few to see how they would look stacked up.

A rough idea of what each panel will look like on the inside

This gives me an enclosure that has an equivalent wall thickness of over 25mm

And after a long few days....

Still a bit rough around the edges to clean up on the square side

The curves came out really well. Don't mind the router burn marks Router is too powerful.

The volume is easily calculated and can be made larger or smaller by adding or removing panels before they are attached. I will decide on final enclosure volume when I decide on drivers.

I had Jantzen in mind but shipping is too costly.

Been looking at Peerless drivers and a Scanspeak tweeter

More photos to come showing progression.....slowly.

[Luc]

Nice! Looking forward to the next stage.

[Nigel]

If they don't work out you'll have lots of dunny seats and lids!

[LogicprObe]

Excellent work!

Are you just going to glue them only or run some threaded rod through and really tension them up?

[Paul Spencer]

A brave move! I might have a couple of builds coming up with curves like that.

If you want different, you might check out some drivers on the HAS website. They have some Seas drivers that are less commonly used. Peerless make some good ones, they are used so often for good reasons. They are easy to work with.

A build like this deserves some nice drivers! Watching with interest ...

[L J T]

Thanks guys.

Luc - The sanding and prep work for the paint will be the most time consuming. MDF takes a while to seal correctly, will take some pictures in the interim with equipment and crossover choices. More pics to follow.

Nigel - Yes they would! Don't worry, I have kept a set aside just for you

LogicPrObe - I have used a wood glue with 32 and 50mm nails to attach each panel starting from the bottom. I had to be mindful as to where the the driver cutouts were placed in relation to the nails. Very strong and very secure.

Paul Spencer - Yes I think I will go ahead with Peerless mid and Sacnspeak tweeter. The Peerless modeled favorably in the enclosure and you are right, easy to work with and has a high EBP. I will use the experience gained in construction of these to make version 2 better.

Things I would have done differently

(1) Machine the front so it's corners are rounded where they meet the sides. I left a squarish edge that needs additional finishing to make them square.

(2) I don't think MDF will be used for the next build. 19mm Marine Ply would be a better choice and would present much better if sealed and stained/lacquered. The profile would have character.

(3) I will add more as it comes to mind

[henry218]

i did this on curve cab

https://mail-attachment.googleusercontent.com/attachment/u/0/s/?view=att&th=1374f2dc84405bdc&attid=0.1&disp=attd&safe=1&zw&saduie=AG9B_P8zL3_VIMeTFoBfiQU7Nmt2&sadet=1346970099227&sads=mZiNPl9zeEG10vbqEO0TWFzT6Ok

[Guest Peter the Greek]

I'd have glued 3mm mdf over the mdf "edge grain" and fitted the top to suit.....easier to finish and better (more consistent) results. Would also allow for veneer if that was wanted.

I love curved cabinets. One of these days I'll make something similar for our other dining/living room.

[L J T]

Henry - Link didn't work for me.

Elill - That sounds like a good approach also.

[henry218]

sorry, this one should work

http://db.tt/G20CmATz

[henry218]

stacked front side

http://db.tt/6UgaPIkZ

[henry218]

i can give u the drawing if you are interested.

it was done under adobe illustrator, no 3d. ive used this for cnc purpose before

[L J T]

Looks good Henry, I was I had access to a CNC, it would have been cut and ready to glue in one day !

Have you completed them?

[Paul Spencer]

Regarding the front vertical edges, much easier to attach a front baffle, which is also easier to machine out the driver recesses. If you round those edges, you can then veneer over. Especially on a smallish box, it's much much easier to just veneer then paint, than go through all the preparation needed to paint over butt joins without getting seams.

Painting over butt joins is a real pest. I've researched this one and tried a zillion techniques. The most effective I've found starts with two part fibreglass reinforced filler - it's like liquid fibreglass, automotive stuff. You apply it thick over the butt joins, over the entire surface and make sure you do it when the temperature is over 15 degrees. Then sand it back and repeat. Then sand again and fill with two part bog filler. Now you "paint" the entire box, inside and out with fibreglass resin. Now you have a stable base to work with. Sand again, and apply another coat. Again, each time, the temperature must not drop below 15 degrees, or it won't catalyse properly. Give it some time to harden before sanding, then fill again with bog. Now spray on primer, followed by a guide coat of a different colour. Sand back the guide coat until you get back to the primer, everything left in the guide coat colour needs to be filled with stopper putty. Now repeat until you are able to completely sand back the guide coat with nothing but primer underneath.

All this to point out the hassles of painting over butt joins. To make it even worse, the above doesn't guarantee seams won't appear!

Just add veneer and you can take out all those steps, and you can take out the fibreglass which can burn your house down if you do something clever like put on a heater to raise the temperature. Your workshop transforms into a Michael Bay film!

[henry218]

this was done in jakarta, i have not complete them yet, i actually sold it to a friend of mine, as i prob wont be back in a while.

i have no direct experience on finishing, but the reason why the front baffle was separated to the front enclosure are

1. i need to cnc the front baffle, the cnc cant do on the box, as it would be too deep

2. i planned to have different finish on front and the rest of the box

3. as i prob wont veneer the curve, as to paul's opinion on how difficult it will be to apply veneers on the curves

u might need to consider making patterns for internal bracing on the middle, as i did intervals between layers with bracings pattern

[henry218]

just realised paul actually talking about the techniques to filling up the gaps between layers.

i dont have this problem since ive used plywood

[Paul Spencer]

Nope ... try painting over a butt join and what do you find? You get a seam! It happens with both ply and MDF.

I wrote about it here:

http://redspade-audi...butt-joins.html

and then followed up later here:

http://redspade-audi...in-samples.html

[henry218]

just realised paul actually talking about the techniques to filling up the gaps between layers.

i dont have this problem since ive used plywood

[henry218]

have u tried epoxy filler? they do great on furnitures

it was also another consideration for me to put 4 bolts, just to make sure its tight.

[henry218]

ok just read your blogs, you did it finally

painting solid color over ply was never my intention, i was planning to varnish it, prob do some sanding sealer and stain it first.

[Paul Spencer]

I thought this thread was about Leon's speakers!

Only just saw your pics Henry, nice work! I haven't tried epoxy.

[henry218]

, i hope our posts helpful in some way to leon.

that curve speaker was an attemp to creat vapor cirrus with my own styling, although cirrus is wave form rather than curve.

with cnc most shape quite easy, but i will never do this again, as it wasted alot of good plys.

OB i think is most environment friendly speaker nowadays )

[L J T]

Yes all good valid points about the butt joins. You have a great blog Paul and I follow it when I can. I also have access to a high quality fiberglass applicator, so that's another option.

I can also use black vinyl as I have done previously for other boxes.

The front panel will be easy to make up and was another idea I had also.

[L J T]

Here is a picture of the internal bracing I used in the enclosures. There are two in each box.

I made it a simple design that is strong and makes the cabinets very rigid.

I liked the design Henry showed me in his build and thought this would be more suitable for mine.

Having the internal wall thicknesses at almost 30mm, I had to think about how I was going to add connections for the speakers from the amplifiers. I ended up finding binding posts that have an extra long thread and will enable me to connect each driver to it's own amplifier. This design is going to be a compact two way active monitor.

For the crossovers, I am going to use one of these

I'll use REW to measure the drivers and find the optimal crossover point for each and their respective time delays that can all be controlled from the MiniDSP

[Guest Peter the Greek]

Just add veneer and you can take out all those steps

I'm not at all a veneer specialist, in fact I will hopefully finish my first use of it today...with any luck......anyhow I have seen a lot of furniture that uses it over the years and it doesn't seem to work on butt joints (you can see the "ripple" under the veneer). you need smooth surfaces or mitered edges from what I can tell