Making speaker cabinets

[simcox1]

I have decided to make a pair of wd25a speakers. I have bought the driver units so far. I found the standard tweeter on ebay. I feel I could really use some advice with this. I am a complete novice, having never built speakers before. I have recently completed a KEL84 kit.

What I need to do next is the cabinet. I don't really have the tools or space to do much woodwork. I have tentatively approached a local timber merchant, who have 19mm oak veneered MDF, and can do cutting. But if anyone has made WD25A cabinets themselves from scratch, I would appreciate some advice. What would also be great, is if there might be a crossover PCB lying around unused somewhere. I did think about getting the EX treble unit, as it is still available from Falcon, and is much cheaper than it used to be. But still quite expensive (£150 each).

Any replies greatly appreciated.

Thanks,

Simon

[Richard]

Hi Simon,

I can't remember if there was a pre-cut cabinet kit available for this speaker. Can anyone help? Thoughts are you may be able to ask the original supplier to do a set of panels - unless someone still has some or cabs they don't need?

Otherwise I've built various speakers and the hardest part (for me) was getting really good corners. The kit designs in the 70's when this was popular suggested 3/4" or 1" square batons screwed and glued down all the panel edges to join the panels together. The corners were often not designed to be mitred (the hard part for most folk) and were butt joined with a finishing strip on the edge.

I had panels machine cut at the woodyard. That does depend on getting a friendly guy to do the cutting accurately and expecting to pay him. I used plain chipboard so they were screwed and glued from the outside and finished in veneer or laminate after so the corners were taken care of, but it was a bit of a labour of love.

For pre-veneered boards you could go for a similar baton and butt joint by screwing and glueing the batons to the panels from the inside. Just re-do the panel dimensions to allow for the butt joints rather than mitred then edge the outside panel edges top and bottom with matching veneer strip.

[simcox1]

Hi Richard. I think the cabinet came pre built, rather than as a kit. But the construction article gives quite clear instructions. One thing I'm not sure about, is the top and bottom panels. It looks like I need to cut into them to leave a 9mm lip all around. I think it's really just a matter of finding the right place to supply the wood and cut everything for me.

My local place is Wood Green timber in Haringey, London. They stock veneered MDF. But I'm not convinced about their service. I just need to know exactly what I'm doing, before I go to them.

Alternatively, I could go out and buy some tools, and try to do it all myself. It would probably be cheaper to get them to do it. I guess I will work it out.

Thanks for the reply.

[John Caswell]

B&Q used to do a very good cutting service, if you bought the timber from them.

John

[simcox1]

I hadn't thought about B&Q. Someone posted a link to Peter Benson plywood, and I have asked them for a quote. I will check B&Q as well. Thanks.

[Edwin]

Simon, I built cabinets for the 25 T a few years ago and I would gladly email you some information about how I put them together because the principles would be much the same. The panels were made of 12 mm chipboard bonded to an outer cladding of oak veneered MDF. The top corners were mitred and there were solid oak strips on all the edges where the front and back panels met the sides and top. I avoided any internal battens to join sides to back and front because I didn't want to change the internal volume even by a small amount.

I would gladly send you details of how I did the whole job. However, I'm not sure how limited your space, experience and toolkit are. The various internal braces have to be carefully cut to a pattern and the cutouts and rebates for the speaker units have to be done with some precision. One indispensable (in my opinion) tool is a router. Though B&Q might cut the panels, I think you would have to find some other means of doing the rest.

Let me know if you think I might have anything useful to pass on to you.

Edwin

[pre65]

I would say having a router (and knowing how to use it) is an indispensable aid to making good speaker cabinets.

I prefer making such things outdoors, and preferably when the sun is shining.

[Greg.]

Today, I spent a bit of time in conversation with Peter Comeau at the Bristol show and, being mindful of this thread, quizzed him on the cabinet construction details. At an early stage of WD under his ownership, I was his speaker cabinet constructor should a customer want their speakers fully finished rather than buying as a kit and I did put some together in those days.

The first WD kit was a WD25A which was an aperiodic designed stand mounter. Peter had a local company, name no longer recalled to produce flat pack kits for the cabinets out of Oak veneered MDF. He had major problems with these because although accurately cut and machined (stepped right angle edges at the joins and recessed panels on the inside for braces), in storage and subject to atmosphere, the MDF swelled and the flat pack kit became ill fitting. This was my experience on construction as every joint would have gaps. For the 25A and the later floor stander 25T's, Peter contracted a company in South Wales to make finished cabinets. This company according to his understanding has now probably stopped trading. At the time, material used was a product they named 'Acenia' which was a layer of veneered MDF bonded to a same thickness layer of chipboard. This was based on Peter's belief that chipboard had the best sonic properties whilst MDF was preferable for construction accuracy and finishing. The cabinet makers at the time did the layer bonding. The MDF/chipboard product was not commercially available from timber merchants.

There is much research on materials that can be used for the best cabinet construction, much of which, regardless of the science, I have become over the years rather jaundiced about. As a DIYer, generally the option will be wood based, albeit mounded concrete might have a place. Some believe in these circumstances, Baltic Birch Ply is the material of choice. Personally, my experience is that this concern is of little consequence. My friend's DIY speakers are made of BBP and my similar sized WAD KLS3's are made of 25mm MDF. In terms of cabinet resonences, I can't tell any difference.

Think about the cabinet as a structure and what it is physically required to do. Simply it is a wood chamber that sits permanently in the position placed and is not subjected to to any external forces other than gravity. Joints therefore do not need to be rebated and all can be simply butt jointed together provided you have your wood cut by a good and well equipped timber merchant, and on assembly, use a good modern glue. This is how mine are done. To keep costs down, I used Oak pre-veneered MDF and for corners had solid Oak edges bonded to the panels so the butt joint did not show any MDF. Your timber merchant can do all this for you to a higher standard than you would probably achieve at home. All that is then left to do is butt glue it all together. You will need to provide a cutting plan for your TM, so some adaption will have to be made in terms of panel measurements from the original cabinet construction plan. The other option is to fully construct in plain MDF and veneer afterwards. It is surprising how many first time veneerers have produced good DIY results.

In terms of the 25A upgrade to the EX tweeter, my unqualified opinion is this would not be a good move. I also worked for Peter as a demonstrator at shows and my personal view was that the EX tweeter was a mistake. Certainly it enhanced transparency but also brought a shrill and glassy edged sound to the treble that was, after a while, fatiguing to listen to. Personally, especially as you have them, I'd stick with the original tweeters.

You obviously know Falcon Acoustics and you should be able to get all the components you need from them for the crossover.

I hope that helps. My only other observation is, are you making this far to difficult than it needs to be. The 25A's and the 25T's were not the be all and end all of home constructed speakers, and in some listening/living rooms they were thoroughly inadequate. There are plenty of quality kits available today that would more than compliment your WD KeL84. For a starter, look at:

http://www.iplacoustics.co.uk and there are plenty more.

[simcox1]

Thanks for your input Greg. If I do as you suggest, and use butt joints, would I be able to do that for the top and bottom panels as well? The reason I decided on this speaker, is partly because I looked at it some years ago, but also because it suits the room I have now. Which is smallish, and they would be close to the wall. I did look at various other places including IPL, but couldn't find anything that particularly appealed to me.

I don't really have a lot of space or tools where I am now. So getting someone else to do the cutting work would probably be easiest. I haven't really found anywhere suitable yet. But there are plenty of timber merchants around here.

Obviously it would have been easier if I'd have chosen a different route. And cheaper. But having bought the speaker units, I still think that this is the speaker I would like.

I will let you know how I get on.

Thanks again.

[simcox1]

Edwin. I would be interested in seeing your plans. If you could send them to me. Any input would be useful I think.

Simon