Laser Cutting MDF from Exeter Laser

I recently bought a couple of (odd and little known) speaker cabinets with drivers; Olle Mirsch OM 2-17.  The cabinets look great (to me at least) but they sounded dreadful; harsh, peaky in the upper-mid, very forward.  I could only listen to them for a couple of minutes before turning off!  That surprised me, I hadn’t expected them to sound that bad – no wonder no-one else bid on them and that Mirsch speakers (from Sweden) are no longer around.  The cabinet construction is not so great either.  But they do look good, here’s some photos from the sale:

Olle Mirsch OM 2-17 Speaker Cabinets.

Olle Mirsch OM 2-17 Speaker Cabinets.

$_57-2

I do have a pair of brand-new, unused E.J. Jordan JX92 drivers (E.J. Jordan is considered the Grandfather of full-range speaker design).  Jordan full-range drivers are what I will be using for my own cabinets but I stupidly bought them too early and Mr. Jordan has now updated the design.  So I will put these great drivers into the (improve by myself) Mirsch cabinets.

The Jordans don’t fit though so I need to reduce the size of the hole in the front baffle.  To this end I got in touch with a laser cutting outfit in Exeter.  I’m so glad I did.  I now have four toroids (2 for each baffle) beautifully cut and I cannot be happier with the quality.  The price also was very good and talking to John I felt confident, they were professional, fast and very helpful.  So when I go ahead with my HiFi cabinetry, Exeter Laser will be cutting the MDF for me.  In fact I have quite a bit of MDF work needed for our home too (only been here 10 years so lots of decorating still to do).

Many thanks to John at http://www.exeter-laser.co.uk:

Laser-cut MDF toroids by Exeter Laser.

Laser-cut MDF toroids by Exeter Laser.

Laser-cut MDF toroids by Exeter Laser in packaging.

Laser-cut MDF toroids by Exeter Laser in packaging.

Before getting the MDF cut, I used MH Audio in the Nederlands (http://www.mh-audio.nl) to work out the base response with the replex ports available from Wilmslow Audio (http://www.wilmslow-audio.co.uk). The 54mm x 140mm port will fit nicely into the treble hole of the cabinet and gives this response:

Base response graph as given by MH Audio of The Nederlands.

Base response graph as given by MH Audio of The Nederlands.

As you can see, it goes down to just above 40Hz (-3dB) but with no peaking just before the drop off. These days, with small drivers, many manufacturers give a hump in the frequency response of their speakers (usually around 100Hz), to make it seem the speakers go lower in response than they actually do. I do not like this pronounced and false response, much preferring a flat, natural and realistic sound. Anyway, many thanks to MH Audio.

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About Matal

Hand made HiFi, photos, a friends poetry.
This entry was posted in Construction, Loudspeakers and tagged , , , , , , , , , . Bookmark the permalink.

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