Hi.
I thought that all compression drivers used the same thread? When trying to mate Eminence Asd1001 with an mrh-80 horn from Monacor it works fine for the first 5-6 turns, but then it jams up. Data sheets for the parts have the same thread. Comparing with a Noname driver the asd1001 thread is slightly off.
Anyone else tried something like this? I'm tempted to cut of some of the internal thread in horn, but it seems wrong. It should fit?
Kind regards TroelsM
I thought that all compression drivers used the same thread? When trying to mate Eminence Asd1001 with an mrh-80 horn from Monacor it works fine for the first 5-6 turns, but then it jams up. Data sheets for the parts have the same thread. Comparing with a Noname driver the asd1001 thread is slightly off.
Anyone else tried something like this? I'm tempted to cut of some of the internal thread in horn, but it seems wrong. It should fit?
Kind regards TroelsM
They are suppose to, but there is variation (QA/QC ? metric conversion? 🙄). My experience so far is .....
Fane CD130 has measured (with calipers) thread OD 34.18mm and thread pitch (3 valleys) 3.23mm and it fits 3 horns and 1 adapter perfectly. The thread is long enough to seat properly in my horns + adapters.
Celestion CDX1-1446 has measured OD 34.86mm and thread pitch (3 valleys) 3.32mm and fits one horn (H07E) that was "worn in" (crude retap) to fit this driver. The thread length is also a few mm short and requires a gasket to prevent an end gap (it creates an HF cavity notch).
Fane CD130 has measured (with calipers) thread OD 34.18mm and thread pitch (3 valleys) 3.23mm and it fits 3 horns and 1 adapter perfectly. The thread is long enough to seat properly in my horns + adapters.
Celestion CDX1-1446 has measured OD 34.86mm and thread pitch (3 valleys) 3.32mm and fits one horn (H07E) that was "worn in" (crude retap) to fit this driver. The thread length is also a few mm short and requires a gasket to prevent an end gap (it creates an HF cavity notch).
Unfortunately, conforming to standards is an ideal often not achieved.
There are a lot of things to get wrong compared to simply drilling holes..
A slight deviation from the standard(s..) requires various "fixes".
Cutting some of the horn threads off may be the best solution, adding a gasket increases the non-expanding throat length, not as bad as a gap, but not ideal.
I've heated plastic horn throats with a heat gun and threaded the metal driver in when it's impossible to seat it properly without excessive force.
Art
Interesting idea, did the plastic retain to new dimension? or could it be removed without reheating?
Yes and yes.
ABS plastic is frequently used, it starts to soften up around the temperature water boils at.
You don't need or want the plastic to get to a flow temperature. Screwing the driver in and out will give you a "feel" of how much heat is needed for the threads to loosen up.
That said, some horns may be made of thermosetting polymer, which does not become "plastic" when heat is applied.
You can test with a hot soldering iron in an unobtrusive spot to see if the material melts.
Art