WD25T Cabinets

[Andyman]

First off, it's quite an eye-opener to realise how much of the speaker budget is taken up by the cabinets (60% of the total if considering the standard tweeter).

But that got me to thinking - how difficult would it be to make my own?

The main problem when starting from scratch, and without access to pro tools is being able to cut things perfectly square, followed closely by ensuring unwobbliness.

And then I remembered reading about some speakers using an interesting cabinet construction. A good memory and a little Googling got me to here:-
www.seventh-veil.com/nonsuchdesign

Although there would be a lot of work involved I think I could eventually knock up a couple of "boxes" along these lines. I believe that the internal volumes required for the WD25T can be slightly flexible which would suit, as there will obviously be a certain amount of estimation going on.

An added bonus would be immense flexibility in shape (Sonus Faber type curves anyone?) allowing radiused edges and an integral oversized plinth. Hmm - think I'm getting quite excited.

And so to my questions.

As a cabinet so constructed will be significantly more rigid than a standard box and also lack parallel surfaces (top, middle and bottom excepted) would it be wise to dispense with panel damping, wadding et al?

Also would the vertical bracing (in particular behind the bass unit) still be required? Need to know in advance as this would affect volume guesstimations.

And finally - do you think it would be worth the time and effort involved (from a sound quality perspective - if they end up looking *****, that's a different problem)?

Any other ideas - clever thoughts would be most welcome.

Thanks in advance,

Andy

[Audiognome]

Whoah ! Spooky !

Andy, something just drew me to re-read your other thread, where you were asking about WD25x and then this post appeared

Just wanted to let you know - the link in your post doesn't seem to work? (webpage not found)

Nigel

[soulminer]

http://www.seventh-veil.com/nonsuchdesign.htm

[Andyman]

How annoying!

Try this http://www.seventh-veil.com/nonsuchdesign.htm

then go to bed.

Andy

[alnewall]

It's not easy doing repetitive cutting of round shapes with any degree of accuracy either. Unless you have access to special equipment, which you say you don't. A jigsaw blade will invariably end up cutting a bevel edge somewhere, when cutting circles.

I think i would be up to my knees in MDF dust and very bored before i finished the first cabinet.
Easier to get wood cut to size by a timberyard, this is usually accurate enough and then go for a conventional box.

Of course you may be considerably more patient than me, in which case get yourself a good dustmask, some waders and go for it.

[Andyman]

Originally Posted by alnewall

It's not easy doing repetitive cutting of round shapes with any degree of accuracy either. Unless you have access to special equipment, which you say you don't. A jigsaw blade will invariably end up cutting a bevel edge somewhere, when cutting circles.

I think i would be up to my knees in MDF dust and very bored before i finished the first cabinet.
Easier to get wood cut to size by a timberyard, this is usually accurate enough and then go for a conventional box.

Of course you may be considerably more patient than me, in which case get yourself a good dustmask, some waders and go for it.

Hmm good point. I do realise how much work would be involved - that's why I originally asked if it would be worth the effort.

I have considered (but not yet at the stage of doing) checking out locally if anyone - presumably witht CNC facilities - could cut mdf to size and shape (possibly a toilet seat manufacturer!) That would leave me with the job of "angling" the inner faces and gluing everything together. That shouldn't be too difficult and even if I messed up the veneering a couple of times, I reckon I'd still have change left from £398 - the cost of the flat pack kit.

Cheers,

Andy

[petercom]

A few points to clarify here.

1) You cannot dispense with the internal fibre as this performs acoustic absorption and damping inside the enclosure air space.

2) Ideally you should keep the brace behind the bass unit as this reduces vibration in the bass unit chassis. However you can achieve this in other ways, for example by a block of wood that connects the bass unit magnet to the rear of the enclosure. Just make sure you don't block the hole in the rear of the magnet which relieves air pressure behind the dustcap.

3) The problem with thick walled cabinets like this is the tunnel that is formed behind the bass unit. The opening for the bass unit should be increased as far as possible internally to reduce this tunnel effect while still leaving sufficient wood depth to accommodate the drive unit fixing screws.

4) For the same size outer cabinet dims doubling the wall thickness has a drastic effect on the internal volume. Remember to always calculate the inner volume first then add the wood thickness (x2) to give the final outer cabinet dimensions.

[Andyman]

Originally Posted by petercom

A few points to clarify here.

1) You cannot dispense with the internal fibre as this performs acoustic absorption and damping inside the enclosure air space.

2) Ideally you should keep the brace behind the bass unit as this reduces vibration in the bass unit chassis. However you can achieve this in other ways, for example by a block of wood that connects the bass unit magnet to the rear of the enclosure. Just make sure you don't block the hole in the rear of the magnet which relieves air pressure behind the dustcap.

3) The problem with thick walled cabinets like this is the tunnel that is formed behind the bass unit. The opening for the bass unit should be increased as far as possible internally to reduce this tunnel effect while still leaving sufficient wood depth to accommodate the drive unit fixing screws.

Thanks again,

Andy

4) For the same size outer cabinet dims doubling the wall thickness has a drastic effect on the internal volume. Remember to always calculate the inner volume first then add the wood thickness (x2) to give the final outer cabinet dimensions.

Aha - excellent Peter and thankyou. These are exactly the sort of clever thoughts I'm after. You may have surmised, I am a complete novice with respect to speaker building, so what may be obvious to you I may well be unaware of.

Regarding 3) I thought that speakers often had baffles of double thickness compared with the rest of the box. If there is a trade off between rigidity and this tunnel effect, is there therefore an optimum depth of baffle?

Also I presume from your lack of mentioning that this tunnel effect would not apply to the tweeter?

As I could cut my theoretical segments to any shape - I can make my "pseudo baffle" any thickness. Also I don't intend the walls to be quite so extreme as the Nonsuch design as I don't want the speakers to end up overly massive.

[Andyman]

Errm...the Thanks again Andy just got weirdly moved!

Andy

[Ianm2]

if you are a novice, its a big enuff challenge alone to build a basic pair of cabinets, let alone trying to do something different

whilst the wood for building your own may be cheap, comparitively, factor in your time, work, labour and hassle, I think you would be far better simply getting the ready made ones, I don't actually think the prices are too bad in comparison to others

why does everyone want to try and do things on the cheap?