Ardent inspired sub project : element and amps arrived...

[cjd]

I would be using birch ply for all of that. For bracing, I'd definitely be using basic cabinet grade birch ply (~$35 for 18mm at the local Big Orange, not sure they carry similar grade in 12mm.)

The bracing in the Nebbiolo is similar, though I went for a 3-axis brace setup and only one vertical in each direction.

I won't use MDF at all though.

[JonMarsh]

Hi you great gurus of knowledge

After struggling along to create my inner braces I have a couple of things that I wounder about.
For my sub here I'm using OSB (Oriented Strand Board) plates for inner braces. Mostly because I had two sheets laying around that the builders left here after they where done building my house.
The OSB is a quite rough material and I do not think I normally would have selected it - but it is also quite dense so I do not think there is any problem using it.I think that the OSB I'm using is 13mm.

What I notice is that it is quite some work to cut out all the holes and cut's in these plates. So what I'm kind of wondering is what plates is the "best" to use for inner bracing. I do see that some uses MDF and some uses HDF.
But if I create a matrix construction, like what B&W (see below) does, what material would you recommend to use? I'm thinking type of wood and thickness.
And how would you connect the braces to the rest of the box?

Please describe your best tips and tricks for a newbie and others to enjoy!

I think the working idea if you use a complex bracing like this is to be able to rely on the only true strength mode of MDF, which is compression. All those cutouts are necessary to have an "open" space behind the driver. This is not unlike what Mike used in his Isis clone build, with a very complex bracing system.



Mike used NC machining "outsourced" to get all those special pieces made.

Me, I had no NC machining available, or lets say, didn't chose to seek it out, and used a much simpler "design language" based on my knowledge of early Avalon products, but also used much stiffer materials.







In either case, the target it to make the wall mode/frequency higher that the highest frequency of bandpass in the cabinet, by increasing the stiffness For a sub, that's not really all that hard in a basic sense. OTOH, you also want to make it stiff enough that you're not wasting energy flexing the cabinet walls. I tend to favor materials similar to what CJD suggests. Except a little more extreme...

I think MDF would be OK for the sub, but I'd go for a composite wall thickness of at least 25 mm, and 18 mm for the braces, and an unsupported span no more than 150 mm (the largest span in the Isiris wall unsupported).

[PMazz]

I always prefer ladder style bracing. Apply solid wood strips to the panel walls from top to bottom and position cross pieces wherever needed from side to side. The cross braces can be ply or MDF strips cut to ~2" wide. You can pre-assemble them and add them while you build (just like the routed braces) or install after the carcass is assembled (provided you have enough room to work). You can't see the side wall strips because of the OC703.

Images not available

[TEK]

Thanks for the input folks. Compared to Jons standard I see that I'm not fully "up there".
The walls on my sub are 20mm MFD (except from the baffel - it is 60mm). The braces are 14mm. I do have unsupported span up to 24cm. I'm not going to start over again for this, but I think I will add one layer of OSB plates on the larger surfaces on the inside to stiffen the cabinet some more. That will give me areas of 34mm for the parts of the sides that has the larges span. This should also be easy to do without any negative impact. And I'm still within the recommended inner volume for the sub kit.

Jon: What kind of material is that you are using?
From what I find out - it seems to be easy for me to get my hands on birch ply in 4, 6.5, 9, 12, 15, 18, 21, 24mm, grade B/BB.
I may also check with a local - maybe they have some more interesting stuff for me...

I have a couple of question that someone might have some input on:
1) I was thinking about laying the inner walls of the sub with asfalth plates (3mm). What do you think? Is that a good idea or is it just wasted inner volume and money?
2) Should the MDF be treated in any way before putting on the veneer?
(I still haven't got the veneer - but I will problably start testing the sub before I get it - and wonder if I should give it a layer of foundation paint before I start using it)

Also - as you know this is the first of two subs. I will revise my material usage and bracing strategy before starting on number two. I will get back to you on that after this one is up and running.

[TEK]

I guess you all are on the Northern CA DIY meet - a bit far for me ;-)
I decided to go for a easy solution, I want to get this one ready for testing - and then male the next box "perfect".

So I have:
- added 4 braces to support the walls better where the larges unsupported areas are
- added the "stand", so the buttom is now 4cm thick

In addition I have
- glued together the box (and the "stand")
- sanded down imperfections
- inserted "dont remember english word" into the MDF to fasten the woofer, so that it screws is not just fastened in the MDF
- used silicon in all inside corners to ensure that the box is air tight
- added 1inch of inside fill for damping
- started to mount the parts together

I will upload some pictures from my phone later on (so they are oriented the right way)

[TEK]

Or some other DIY event, seems as there is several going on...

Gluing the base plate


Inner braves before stuffing


Completed box (except venering)


Inside after stuffing


Completed boc (except venering)

[TEK]

Hi

Then everything is put together and testing has begun.
The impression is what I hoped for, and expected so I am quite happy with that.
- the bass is more defined than With my 18", more "musical"
- it is also not as deep, but thats expected - and is also part of the reason why I am building two

If I should sum it up I would say that the New one is more suited for Music, while the old one was better for movies.
Hopefully - when I have two up and running - the answare will be that they are better for both music and Movies ;-) If not there will be 3 subs in my theater room - the two new ones and the old one :-P

But I need some input. I had forgotten about the grill. What material do you use to create the grill frame? I`m afraid that it will be twisted if I`m using the wrong material.

[JonMarsh]

I found some HDF like material at my local HD, which will be combined with another material and cut on a bevel, so the grille frame will overall have about 6mm or a bit more of depth. The bevel will match the panel bevel on the edge. I don't think they'll twist or warp- the black grille cloth I bought is moderately sheer, from Meniscus. That doesn't help you where you are, though, I'm afraid!

[TEK]

"I may also check with a local - maybe they have some more interesting stuff for me..."
And this is my local woodshop. Not much hope there :roll:

[JonMarsh]

Wow! That's stark!

I'll be working on these soon, so I'll show you what i come up with, if you're not in a screaming hurry...

[TEK]

Thanks Jon, that would be great.
No hurry - right now the raw edition of the first sub is playing in my theater.
I guess I will start the design process for the Mark II edition (the second sub) as well as getting the material for it.

Regarding material:
I understand that you "actual professionals that call yourself hobbyist ;-)" is not that found of MDF as the material for high quality subwoofers and speakers. As building the subs is kindof an exercise to building the Ardent in the future I will try to use the right material for my Mark II sub.
But I also have to consider what material I can get my hands on.

Currently it seem as if birch ply grade A/AA is my best choice.
I also think that limiting the number of different thickness should be a goal (to aviid having to many different types of plates)

What do you folks think about a design goal of 3cm thick walls and 6cm baffel. All in birch ply.
Using 20mm and 10mm sheets glued together for sides. And 10mm for inner bracings - or is that to fragile?

How would you have done it?

[cjd]

Is what you have really so sub-par?

The panels should all be so much shorter than the frequencies a sub will see as to be a (mostly) non-issue, unless you're observing notable flex under load.

I did a Tempest (original) in a 24" cube (external dimension) in 36mm birch ply (two 18mm laminated) and a single brace very much like you started with - one down the middle in each direction, fitted together. I've never EVER felt the sides complain, nor does it walk...

My HT sub is a 4xTempest-X beast (opposed mounted in 36mm birch ply 20x18x36" manifold), so I'm not sure that how I do things helps you much.

The next subs I'm building will be 4xMaelstrom 18's (original pre-order) open baffle... nope. Still not much help.

C

[TEK]

Is what you have really so sub-par?

Sorry, but I dont get what you mean by that...

The panels should all be so much shorter than the frequencies a sub will see as to be a (mostly) non-issue, unless you're observing notable flex under load.

My HT sub is a 4xTempest-X beast (opposed mounted in 36mm birch ply 20x18x36" manifold), so I'm not sure that how I do things helps you much.

I guess you are telling me that 20mm + 10mm birch ply, and using 10mm for inner reinforcement, should be plenty enough for my sub?
Maybe even 20mm ply and 10mm inner reinforcement?

From the one I have buildt now I have to say that I dont think I notice any flex under load. When running it at very high output I do notice that it's vibrating, but I'm kindof thinking that it is the whole sub that is vibrating, not the walls that is flexing. Hard to tell tough...

The next subs I'm building will be 4xMaelstrom 18's (original pre-order) open baffle... nope. Still not much help.

C

Hmm - I kindof wonder if you actually are working on house demolition:W
With my single 18", and to some degree also my new single 15" sub I can actually rattle the house. One issue I'm seeing when testing my sub's is noises from furnitures or construction parts. The "twinkle little star scene" from Nemo is very good at that 8)

4x18" Maelstroms? Are you sure your house can handle it?

Have anyone of you folks actually experienced constructional damages to your house when driving your extreme subs to the max?

[PMazz]

Have anyone of you folks actually experienced constructional damages to your house when driving your extreme subs to the max?

Oh yea! I had to run drywall screws in my HT ceiling so it wouldn't come down. Damn builder used nails and NO GLUE! Besides that, just the normal rattles and buzzes that needed attention.

[TEK]

Can't help on where to buy. If you want easy, try a P&S (Peel & Stick) backed veneer if available. It works like contact paper. As for the type of ash, plain sliced or flat cut will have the usual wavy grain pattern while rift cut or quarter sawn will be more parallel straight-grained. You'll pay more for rift cut but won't have to be particular about aligning the grain pattern on a panel, and thus, less waste. With the facets on your enclosure, I would recommend 10 mil paper backed as it won't show a thick edge on adjoining sides.

Here's Quartersawn:

http://www.veneersupplies.com/products/Paper-Backed-Ash-Veneer-Quartersawn-4-x-8.html

And Flat cut:

http://www.veneersupplies.com/produc...Cut-4-x-8.html

Just ordered from veneersupplies.com...
Ended up with this one:

http://www.veneersupplies.com/products/Paper-Backed-Ash-Veneer-Quartersawn-4-x-8.html

with PSY backing to make it easy for myself.
Hefty transport cost - but I was not able to find a norwegian supplier with close to same or better price.

Thanks for the input!

[PMazz]

:T I would recommend applying a thin coat of white glue to the enclosure and letting it dry. The PSA backer will adhere better. Be especially aware to seal any raw MDF edges with the glue.

[TEK]

Thanks PMazz.
I will do that. I expect that ordinary wood glue will do the job.
More exactly this:

http://m.casco.eu/produktinfos.php?id=671&bereich=15&produktgruppe=99

[TEK]

Just swell...
"A few moments ago, I sent you an email indicating that I had your order ready to ship. However, I just realized that you also have a paperbacked veneer in your order. I can not ship paperbacked veneers overseas"
Someone in high places dont want this to be easy:roll:

[cjd]

Any idea why?

Trying to figure out if someone over here can help out without ending up trying to ship something illegal or something.

[TEK]

It was just that the supplier did not want to ship overseas he said.
It's a well known issue, and there are services in norway that handle this. You get a local US address, ship the stuff there and they ship it to Norway.
I assume I will be able to handle it.

I have actual found that I - by using my sleeping company - is a place in Norway that I can order from as well.
But that is actually costing me quite a bit more than importing myself, and they do not have the PSA backing.

So I think it will play out OK in the end, but it's supricingly hard to get my hands on some decent veneer...

[TEK]

At last, something seems to go in the right direction.
Was at the wood shop today and picked up some birch ply. They had it and I got it cut in pieces of 122x122cm so that they should be easier to handle.

Very different from MDF, so I'm quite eager to check out how this material is to work with.
Got one sheet og 21mm and one sheet of 9mm.
Planning to use 21+9 for side, back and top. For the botton I will use 21 + the "foot" on 20mm (MDF). Not sure what I will do with the braces jet.

[PMazz]

You could use TomW's old trick of assembling the enclosure out of the 21mm then lining the interior with strips of 9mm then 9mm braces. You would need some way to fasten the interior strips, usually a pneumatic fastener.

[TEK]

Thats interesting.
Is there anyone that have some thoughts to share on pros and cons of combining matrials, for example ply and MDF?

[PMazz]

If, by combining materials, you mean the ply and MDF, it was to accommodate doing a piano black finish.

[TEK]

Sorry about the bad spelling. Writing on the phone and pad and have a tendency to miss the keys, so that for example m becomes space ...

PMazz: if not doing piano gloss finish - would you have used only ply (if quality was your main focus)?
PS: Those looks really nice!

[PMazz]

These weren't designed by me, I just did the construction and finishing. For subs, I don't think it really matters what you make them out of, as long as they don't flex and are heavy enough to not dance around the room. Full range speakers have other considerations. My only beef with plywood is the general lack of quality I see today vs years ago. There is even some "baltic birch" ply out there now that is complete crap. MDF, OTOH, has remained consistent.

[TEK]

Hi

I know this is a long shot, but...

I'm in Berlin now - social trip with my vife's work.
Is there any hifi shop or elements shop that I should try to visit while I'm here? Or maybe a veneer shop :-)
(As most of you know - Ardent is a future project ;-)

Any hints or ideas is appriciated.

[TEK]

OK - finally some progress again.
Got the veneer some weeks ago, but it took some effort to get around to actually move the sub out of the theater and take it apart for veneering..
Just the top of the front and the front left to veneer. The veneer is actually very easy to work with. I just cut it into approx the right size (slightly oversized), using a nife to cut away whats outside the edges, and finally sand down until the edge is even.



Hope to get the veneering done tomorrow. The next step is to get it close to black in color.
Anyone that can suggest a product to stain it?

[JonMarsh]

Here there are aniline dyes and other products to stain black - but I have no idea what would be available in Norway? I'll post some things later ths weekend, hopefully can't point you in useful directions.

[TEK]

That would be great!
This is the color/finish I'm looking for:

[PMazz]

I use thinned black paint. Oil based is better, if you can still find it. Apply like stain.

[cjd]

You should at least be able to find pigments and materials for an oil based black *something* at a good art store... Though learning the particular alchemy to turn that into something useful may be an interesting ride.

The veneer is going on beautifully. What glue technique are you using?

[TEK]

You should at least be able to find pigments and materials for an oil based black *something* at a good art store... Though learning the particular alchemy to turn that into something useful may be an interesting ride.

The veneer is going on beautifully. What glue technique are you using?

I'm cheeting ;-)
Using peel-and-stick veener, have to say that it is really easy to work with. I also followed PMass suggestion about having a layer of wood glue on all MDF ends before applying the veneer. I think that was a good advice, the MDF is much more "solid" after applying a layer of wood glue.

I found this oil baised stain that looks very promising - but I wont be able to test it in a couple of days, they did not have it in the shop so I had to order it. Hope to get it soon...

http://gm.flugger.com/en/prodsikk.dll?SPROD=ON&SPROD-NR=LAKBEJDSE&GO=Vis+udskrift

[PMazz]

Do you intend to spray?

[TEK]

No, I think I will use paint brush. It's do much hassel with spray paint, and really hard to contain the paint dust.
Have some scrap pices I will test on.

[PMazz]

If it's drying too fast for a brush you may want to try applying it with a roller (foam) and brushing out immediately after. While you're testing you may also want to try wiping with lacquer thinner after it dries.

[TEK]

"try wiping with lacquer thinner after it dries"
After it dries? What does that do with the surface?

After the final stroke (planning on using two strokes), do you sand it down with, for example, 400 sandpaper and polish or do any simular treatment?

[PMazz]

Wiping with thinner can create a "rubbed thru" look, depending on what you may like. I threw it out as a suggestion so you could explore some options.

If you're not going to topcoat, you'll need to sand at least once. I would sand very lightly after the first coat and hopefully it will stay flat with succeeding applications. The label says stain, which usually means it has to get a topcoat, but the description hints at a one step product.

We always use flat black lacquer and then topcoat but we're spraying.

[TEK]

Progress...
(Actual some days ago now)

[cjd]

That sure is a nice clean grained veneer. Nice stuff!

[Hank]

Tip: A few years ago, I was building an external crossover box for a customer, and the dye I tried wasn't as deep a black as desired, so I tried India ink and it worked great.

[JonW]

Wow. That is one cool looking sub cabinet. I am biased, liking facets and all. The veneer is really sharp and very well applied (what type of wood is it?). Nice job. :T

[TEK]

Hi
Thanks for the nice words.
I finally have gad some progress (things takes time)...

I have applied two stroke of the black laquer.
Result shown in image below

I'm very happy with the result.

Any advice for what to do now?
Dont do anything more?
Or rub it with some 1000 sandpaper and do some kind of final polishing or something?
I'm not planning on clear coting it.

JonW: the veneer is quartersawn white ash (peel-and-stick)

[JonMarsh]

With just two coats on, I wouldn't do any follow up sanding. If it's smooth enough for you, I'd leave we'll enough alone with what you've got. But myself, I would clear coat it a couple of layers- but I like satin clear coat over black.

I'm in the Edinburgh airport, heading back to the USA.

[TEK]

Thanks Jon. I notice that it is a bit "rough" to feel. Guess it will attach dust in it current state - so mybe some more treatment is needed.
You suggest more layers of black first?
Then rub it down, clear coat, rub, clear coat? Is the final task to clear coat - or do you rub down and polish or something?

And welcome back ;-)