Building some WMTMW

[quickshift]

I've started building some WMTMWs with phisically time aligned drivers. Here are a few pics of the construction. They are technically prototypes so I can take measurements with a view to trying to attempting a transient perfect response. The drivers are physically aligned at a distance of about 10 feet. These boxes will be replaced if I can't reach my goals with them.



Basic box construction. 18mm and 25mm MDF. The green stuff is acoustic damping material and the white things are polystyrene hemispheres which will be glued onto the damping material on all parallel facing walls.



Baffle panels cut and checked for correct alignment



Driver holes cut and baffle panels glued together.



£18 worth of veneer and a coat of Danish oil - I really need the practice so I thought is was worth getting some veneer even if the boxes will be junked.

[sdclc126]

Excellent work - they look like very stout boxes. What drivers will you be using? What are the overall dimensions?

[quickshift]

Thank you. The drivers will be Seas L22RN4X/P, Peerless HDS152 and either Seas H1212, H1318 or Peerless HDS tweeters. I have both Seas tweeters to try and as they are all the same size and will all work, maybe it would be nice to try them all.

The boxes are 90cm by 28cm. I'm building something nice for them to sit on to bring the tweeters up to the correct height.

[tinitus]

Seems you understand the art of building a 3way with proper time alligned drivers

[sdclc126]

Regarding your tweeter choices, I think you will find the H1212 the pick of the litter - I own it and can vouch for it. The Peerless tweeter though excellent is a little less forgiving when it comes to crossover design, as well more expensive.

All in all great choices - what are your plans for the crossover?

[quickshift]

tinitus, lets hope they work as intended

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I do like the H1212, I use them in my front HT speakers. I also tried them in some 2 ways but the top end was a little harsh for some reason so swapped them out for H1318 which softened the top end and gave a slightly more relaxed sound to the speakers. The harshness was probably due to something I was doing wrong.

The crossovers will be (I hope, since I have the boards and parts) ESP 4th order electronic using LM6172, project 9. As I'll be using speaker workshop a fair bit over the next weeks or months I may also try making some passive crossovers as an experiment.

[Cal Weldon]

Good looking boxes ya got there.

[quickshift]

Originally posted by Cal Weldon
Good looking boxes ya got there.

Thank you

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Bit more progress today, the baffles are sanded, primed and a few coats of satin black laid down. There are a few little issues but if these boxes work OK, a quick rub down and a few more coats of satin will sort them out. I'm assuming they'll need to be a mark 2 version so I'll crack on with actually building them.

All things being equal, I should have them working tomorrow



Baffles laid in place to check the drivers still fit after painting, the tweeter cutout will need sanding round the edges a bit.

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One very useful thing I learned. If you spray the edges of cut MDF with clear lacquer before sanding, you get a much cleaner finish. It's especially useful on driver cutouts because it helps prevent the edges from rounding over when the baffle is sanded down.

[ShinOBIWAN]

Cool stuff, good to see your putting those Seas to work. I'd have thought the surrounds would be starting to rot by now

[quickshift]

Originally posted by ShinOBIWAN
Cool stuff, good to see your putting those Seas to work. I'd have thought the surrounds would be starting to rot by now

You've got an impressively good memory The Seas have been sitting on a shelf in my basement for about 2 years now. They are fine apart from a pin dent in a cone which happened during a move.

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OK, well, the speakers are now working and they really don't sound too bad at all. The presentation is pretty good IMO, wide and open without being too "big" for the spoken word.

I think the acoustic damping material must work too as there is no "MDF thud" http://www.customaudiodesigns.co.uk/...oofing/t60.htm I bought half a roll from my company as it was left over after fitting out the recording studio.

So, I'll take some measurements today to make sure the chosen crossover points are about right and then build the crossover.

There is a bit of a gap between the baffle and the rest of the cabinet Room for an improvement or change of technique required there...

I'm glad I bothered with veneering practice too as bare MDF isn't very attractive.