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In the Forum: Horn-Loaded Speakers
In the Thread: Macondo's Axioms: Horn-loaded acoustic systems
Post Subject: High-speed precision hair splittersPosted by jessie.dazzle on: 3/10/2008

Romy wrote :

"...The table on the picture above is very good but it is $180 each. It will be my way out if I do not found anything beter..."


Romy,

$180 does not seem expensive for such a table; for that price it is likely to have been "Made in China", which is probably perfectly fine for the intended application.

Most of these tables have a built-in pre-load adjustment which allows compensation for "wear" (which really means lack of precision) in the mechanism... If so equipped, you should be able to remove all play from the adjustment mechanism, meaning that even the slightest rotation of the adjuster wheel will result in movement of the table. (If you decide to go for it, make sure the table position can be locked, and don't forget that you will need the "T-bolts" to interface with the slots in the table).

Since in the case of the MF horn + driver we are only talking about a max of about 25 lbs load, in terms of robustness, this table is sort of over-kill... Not a problem, but there is certainly a less heavy-duty, yet precise and possibly less expensive option ; something along the lines of the positioning mechanism for a photo enlarger...

You might look into a "ball screw driven carriage"

Something like this :

http://www.jena-tec.co.uk/linear-actuators.php
Scroll down to the manual adjusters

Or this :
http://motionsolutions.com/Catalogs.htm
See the LC 46 Actuator

Or this :
http://news.thomasnet.com/fullstory/494204

The above stuff will likely not be cheap.

It is also possible to make your own zero-play adjuster using parts of more humble origin... Having said all that, I think I would just pay for the over-kill ready to go solution; it should make fine tuning the time-alignment a real pleasure.

My own adjustable frames are nearly done (see the jessie dazzle project thread)
http://www.goodsoundclub.com/Forums/ShowPost.aspx?postID=4941#4941

In my case the position of the horns is infinitely variable within the range of each pair of sliding rails. I had thought of incorporating a precision adjuster of my own design, but for the moment have elected against such a luxury, reasoning (perhaps incorrectly) that I have the patients to get it right without, especially since it is not something I am likely to change every day. In any case, this sort of addition would be simple to incorporate later.

I will be following your progress should you decide to go ahead with this addition.

jd*

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