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In the Forum: Horn-Loaded Speakers
In the Thread: 3 way Tractrix Horn Build Questions - and Introduction!
Post Subject: MDF is a $%^&Posted by anthony on: 1/25/2021
HifiOrDie, I've turned my own horns from MDF and the end-grain is a real bitch to finish properly.  You have the outside of each sheet and the glue in between which is nice and hard and then softer material in between, sort of like tiger or zebra stripes or hard/soft/hard/soft et cetera.  The end-grain takes a lot of sealing properly if you do not want problems years down the track and of course if you sand it too much then the hard bits stay high and the soft bits get low.  But it is cheap to buy and easy to cut on a lathe.

I've not turned horns of anything but MDF on the lathe but other hardwood things have been a doddle to finish properly...not saying that soft Maple is great, but there is probably less work finishing and painting the horns than with MDF.

See below a photo of the front half of one of my Upperbass horns on the can see the tiger stripes of hard/soft/hard.  That horn is 1m diameter and weighs 85kgs and used 3 litres of primer for the first six coats.  Then I sanded it back smooth, or relatively so, and have now applied another six coats of primer which I will sand back to see what I have got.

UB Horn on Lathe

Anyway, that is probably one reason why your guy does not want to use MDF.

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