Shed/ Monitor Speakers

[needsmorecowbel]

So i found out today that the woodworking/ guitar making shed is about 7 weeks away from completion - plastering and electrical fittings all that is now required + painting. Now have a four week wait to plaster the damn thing. It started out as an Idea around August last year and my family figured we'd have it all up and running by December last year. But after some engineering issues from the shed manufacturer (they wanted to put the door in the wrong spot and had to re-engineer haha) and a few setbacks we're finally getting there hopefully i'll be able to get stuck into some building in 10 weeks or less. Shoutout to Rob (Auscab) for his workshop/ machinery wisdom and for Frank's (Vendenboom) suggestion for using foilboard lining- on a 35 degree day the colourbond shed is very lucky to reach 28-30 degrees. here are some pics (some people have had issues with the link but imgur is quite reliable)

http://imgur.com/a/gMZBL#0

Also been working on a refurb of an old Woodfast Planer from 3ph to single phase:

http://imgur.com/a/I6eaG#10

Got an interesting request from an old school mate today which was to possibly make a pair of high end monitor/ studio recording quality speaker boxes. He said he doesn't have much knowledge regarding the design of the box. I was thinking that as long as the thing was fairly airtight and projects towards the soundports (as with a guitar) there wouldn't be much that could go wrong with the thing other than rattling from the internals/ screws/ resonant frequencies/ wolf frequences. One suggestion a mate had was to avoid using wood that had the potential to develop even minute cracks in the grain as with drums if the ply/ solid timber cracks from the vibrations over time it may ruin the sound of the speakers. Any interesting Ideas or suggestions are always appreciated?

Stu

[auscab]

That is going to be one nice workplace Stu. The woodfast is looking good too .
It has two guards ? never seen one like that .
And a doggy to lick up the HHG drippings as well.

[auscab]

Oh, and speaker boxes, I made a pair of boxes for a pair of Tannoy Dual Concentric's once.
The guys at the shop where I bought them said make them as solid as possible, with bracing and lined on the inside with bitumen based carpet then padded out.

I did them from 25 mm Mdf veneered in Mahogany and the bracing around the inside is 50 x 50 mm hardwood . they sound good . the good thing is you need two people to lift them anywhere , there has to be two people dumb enough to want to steal them at the same time.

I don't know if this would be the recommended way to build them now ,it will be interesting to see what others say.

[needsmorecowbel]

Cheers Rob I really like the way the planer is coming together didn't know if the red and green would work out but it looks pretty good. Yeah It must be an old one (60s or 70s) to have two guards but that is the way it came.The mate wants to build the speakers out of "expensive looking hardwood". I told him if he really had a ridiculous amount to spend on wood get some ziricote from the states...otherwise I got heaps of that Otway fiddleback blackwood or could do it out of solid Black Heart Sass. The other option would be to use some cheaper plain blackwood as a base and then just do a tiger myrtle veneer/ walnut veneer. That is if he isn't scared off by the very little amount that I quoted him...

[Trevor Gore]

Speaker boxes, eh?

Can be as easy or difficult as you like. Depends if you want to design them or not. If you go the full acoustic design, expect some hard work, or at least get a well respected set of drawings and build to that design.

I built two pairs of speaker boxes last year, a rear loaded horn, full range driver design. 47kg each unit, when fully loaded. Here's what they look like inside:

The general rule is don't use solid wood, because, unlike a guitar, you don't want any panels vibrating, not even a little bit. So the material of choice is 19mm Baltic birch ply, which is where a lot of the mass comes from. In this design, you tune the "horn" to the resonance of the driver, and that flattens off the frequency response. It's a very "fast" design, so acoustic instruments sound, well, like acoustic instruments. I had some pretty decent speakers before these, but these are a totally new experience. Only 30 watts a side, but easily rattles all my ceiling panels. Pianos actually sound like real pianos. First time I'd heard a speaker get even close.

Here's a detail of the finished ones I kept for myself. I lucked out with some really nice swirly grain birch ply, so did a bit of guitar style binding and French polished them.

Front detail.jpg (68.73 KiB) Viewed 18964 times

They're 1220 high by 310 across by 450mm deep, if you were wondering...

[needsmorecowbel]

Invaluable advice Trevor. I was thinking of just throwing in the towel when the client thought that it was a bit expensive to make two custom hardwood cases 400 mm tall, 300mm wide and 300mm deep for around $ 350 + materials. I also was worried when the words "cranking" was used in conjunction with the words high end stereo system and "party". This could only end in disaster I thought to myself- distance yourself. I am however far more optimistic now that hardwood has been thrown out the window. Cool pebbles by the way

Stu

[Nick]

I was about to say that there was quite a science to building speaker cabinets (especially monitor/reference cabinets) but Trevors shown it far more eloquently. Beautiful cabinets Trevor and even chucked in a bit of Purfling!

[Trevor Gore]

Invaluable advice Trevor. I was thinking of just throwing in the towel when the client thought that it was a bit expensive to make two custom hardwood cases 400 mm tall, 300mm wide and 300mm deep for around $ 350 + materials.

Hmmm. You may need to get him to look up the price of monitor speakers. The "real" ones start around $10k/pair. Add another zero for the expensive ones. Big enough to house a small family.

There's some open baffle designs around, which are basically little more than a half sheet of ply with a drive unit mounted in. Relatively easy to build, but the right design matched to the right drivers is critical. There's heaps of speaker forums if you want to get into it. One of the real gurus of speaker design was Dr. Neville Thiele (OAM), sadly passed recently, who was kind enough to write an endorsement which appears on the back of "the book".

[needsmorecowbel]

The "real" ones start around $10k/pair. Add another zero for the expensive ones. Big enough to house a small family.

See the problem is he's jumped the gun and thought he can make a pair of speakers with the kind of attitude: "how hard is it to make a box" then gone a step further...."hmmm now to find someone to make me a basic box". Instead of having the attitude: oh I think i'll do some research into how they make these speakers and what is right for my situation.

From what you guys have demonstrated it is actually quite damn hard. That B/B birch ply is pretty pricy too $90-100 for a 1200 x 2400 sheet.

Again I know nothing at all about speakers/ monitors but I would have thought a basic P.A system would be far more useful for "cranking" music at parties. I figured monitors were more of a specialised thing for neutral playback of studio recordings (as that is the only situation in which I have seen them used)

Stu

[needsmorecowbel]

Are your speakers super loud Trevor? Or is it one of those things that you don't risk testing with such high fidelity audio? I know I have always been nervous to put my valve amp to full volume...in your experience does the same apply to monitors?

Stu

[DarwinStrings]

That is a fancy looking speaker Trevor, are you sure you didn't get the plans mixed up with some Tuba plans. That looks like a good price for Birch ply Stu, wish I could buy it up here as the last time I bought Birch ply at 2mm thick 5 ply it was about $100 a sheet that had to add postage on top.

Jim

[Trevor Gore]

Are your speakers super loud Trevor? Or is it one of those things that you don't risk testing with such high fidelity audio? I know I have always been nervous to put my valve amp to full volume...in your experience does the same apply to monitors?

The drivers are rated at 30 watts RMS/side, but I have them hooked up to a very conservatively rated amp of 55 W RMS per side, so plenty of potential to blow out the cones if I'm not careful. Also plenty of backup to drive transients, which is what counts. They are also very efficient, much better than than standard infinite baffle, sealed box designs. So I've never run them at much more than "4" on the volume pot, and that's enough for them to be heard two blocks away with all the doors and windows closed. 3 on the vol pot has a grand piano sounding like it's in your front room and that's about the volume I listen at. I suspect I'm not using more than ~10 watts RMS/side (but with a lot of grunt to back the transients).

[Nick Payne]

There's supposed to be an organ music enthusiast somewhere in Canberra whose listening room is designed as an acoustic horn. Here's a couple of pics of someone's home setup in Italy. On the right is the subwoofer acoustic horn under construction (it's under the floor of the listening room), and on the left is the actual listening room. According to the text, the drive units for the subwoofer are sixteen 48cm (18") woofers!

[Trevor Gore]

See the problem is he's jumped the gun and thought he can make a pair of speakers with the kind of attitude: "how hard is it to make a box" then gone a step further...."hmmm now to find someone to make me a basic box". Instead of having the attitude: oh I think i'll do some research into how they make these speakers and what is right for my situation.

From what you guys have demonstrated it is actually quite damn hard. That B/B birch ply is pretty pricy too $90-100 for a 1200 x 2400 sheet.

I think, like a lot of terms, "monitor" has been down graded to mean "speaker", just like "hi-fi" was downgraded to mean "stereo". It sounds like all he wants is loud, and if that's the case, the off-the-shelf stuff is a lot more cost effective than any one-off design.

B/B ply, around here, at 19mm thick is ~$160/sheet, if you pick up. Each one of those boxes of mine uses almost exactly a full sheet (neat design) but you only get one chance of cutting it, because if you screw up, or get one of the bevel angles wrong, you don't have any spare.

[Trevor Gore]

Here's a couple of pics of someone's home setup in Italy. On the right is the subwoofer acoustic horn under construction (it's under the floor of the listening room), and on the left is the actual listening room. According to the text, the drive units for the subwoofer are sixteen 48cm (18") woofers!

Ha! A drummer! He'll be deaf anyway, so maybe that's why he needs so many speakers! He needs to be careful that that 000 in the corner doesn't get sucked up in the turbulence.

[needsmorecowbel]

Well he wants a loud box for party use that has really good sound quality. I just suggested he go out and spend 800-1200 bucks on something with a warranty rather than risk creating something that he potentially doesnt like the sound of which he may be stuck with. Definitely a fairly large risk if he doesn't know much regarding the design/ phsyical parts he wants to use.

[nnickusa]

Sage advice

[needsmorecowbel]

I must say though Trevor I am quite annoyed that you keep making these amazing things as you just keep putting things on my to do list .

[needsmorecowbel]

Sorry a 18 mm sheet at 2440 x 1220 is $ 175.08 inc GST. A mistake on those bevels would really hurt the bank

[Trevor Gore]

Sorry a 18 mm sheet at 2440 x 1220 is $ 175.08 inc GST. A mistake on those bevels would really hurt the bank

It certainly focuses your attention. I got through 4 boxes without a major screw-up, but had to do some imaginative layout to recover from one small glitch. It gets really hard if you decide to grain-match the pieces around the visible parts and then there's having to deal with the bandaids...
(on the wood!!)

But you can always look from the glass-half-full point of view. If you screw-up a cut, you should have a lifetime supply of great ply for endless jigs.

[needsmorecowbel]

It would make lovely jig wood. Where did you acquire your plans for the speakers?

[Trevor Gore]

The original design was by Ron Clarke: http://www.frugal-horn.com/ronhorns.html

Plans are at the bottom of the page above or here.

Needless to say, I tweaked things a bit...

If you live with someone else, make sure they don't mind having the furniture re-arranged...

[kiwigeo]

Propeller heads

[charangohabsburg]

Thanks for sharing your shed construction progress pictures Stu. Your planer makes me jealous as well.

Propeller heads

All went to show me that i wasn't as smart as my boss thinks (if ya cant stun them with brilliance, buffalo them with BS is my motto).

[needsmorecowbel]

No worries Markus I am really looking forward to geting to making some cool stuff.

All this talk of boxes has rekindled my desire to make a media centre. Allowing you to watch TV, youtube, Movies, Internet from a small PC/ box connected to the TV. I have a whole bunch of spare computer parts so should be able to throw together a really nice PC for only the cost of a PSU, CPU and a Hard Drive (like 200 bucks).

Probably use some spalted curly maple for the front and top of the box... along with some plain blackwood for the base and sides.