Mass tweeter array assembly

[Bill Fitzmaurice]

My question is whether this slight deviation from the specs in the plans is going to cause any performance problems once I get the cabs built? I'm guessing that it won't, but I want to make sure before I spend a lot of time getting the arrays completely assembled.

That much deviation won't be bad. I did try some cut down about 1/4" more than that and the results were not good.

[David Carter]

My question is whether this slight deviation from the specs in the plans is going to cause any performance problems once I get the cabs built? I'm guessing that it won't, but I want to make sure before I spend a lot of time getting the arrays completely assembled.

That much deviation won't be bad. I did try some cut down about 1/4" more than that and the results were not good.

Thanks, Bill. I will proceed and hope for the best. Just out of curiosity, what effect did it have on performance when you cut too much?

[Bill Fitzmaurice]

Just out of curiosity, what effect did it have on performance when you cut too much?

Loss of sensitivity.

[gdougherty]

I've been working on melded arrays for a pair of DR250's using gdougherty's assembly process. I cut them all down to 2 inches (except the ones on the ends), and glued them together in groups of five. Today I made the angle cuts on each group of five. I realized after cutting the first group that my measurement was slightly off, and the length after cutting was about 1/16" short of the specified 3-3/8".

You may want to test the 45 degree cut with a piece of scrap wood. I sometimes find it hard to get the lengths right when cutting angles on a table saw. Measure twice cut once. Piezos are cheap but messing up a set of 6 or two gets a little costly.

[David Carter]

I've been working on melded arrays for a pair of DR250's using gdougherty's assembly process. I cut them all down to 2 inches (except the ones on the ends), and glued them together in groups of five. Today I made the angle cuts on each group of five. I realized after cutting the first group that my measurement was slightly off, and the length after cutting was about 1/16" short of the specified 3-3/8".

You may want to test the 45 degree cut with a piece of scrap wood. I sometimes find it hard to get the lengths right when cutting angles on a table saw. Measure twice cut once. Piezos are cheap but messing up a set of 6 or two gets a little costly.

Yep, I saw your warning--it's completely my fault. I tried doing some measuring and test cutting, but I had an abrasive disc blade on the saw so I couldn't cut wood with it, and I ran out of dud piezos before I got the measurement exactly right so I made the choice to go for it knowing full well that I might be off a little. It didn't turn out too bad, so I'll hope for the best given Bill's comments.

[gdougherty]

Sounds like no worries. There does seem to be a bit of tolerance in all aspects of Bill's designs.

[jbell]

I've searched many posts -- and one thing I've not seen discussed is protection of the piezo element from any dust created by using an abrasive blade and/or sanding after assembly to clean things up.

Is it prudent to put tape or something over the element, to keep the dust out while cutting? (or even remove the element altogether?)

[LelandCrooks]

remove the element altogether?

There it is. Especially for the melded.

[Bill Fitzmaurice]

I've searched many posts -- and one thing I've not seen discussed is protection of the piezo element from any dust created by using an abrasive blade and/or sanding after assembly to clean things up.

Is it prudent to put tape or something over the element, to keep the dust out while cutting? (or even remove the element altogether?)

If it's going into a box the horns need to be glued airtight anyway, and that requires removing the elements. For an OTop installation airtight horns aren't a necessity, but gluing them to prevent vibration is still a good idea. But abrasive blades don't throw off much dust, they mostly melt their way through the plastic, so it's not a major concern.

[jbell]

I'll be embarrassed if I just missed the step of 'removing the elements' from the plans.... I just didn't see it.

[Bill Fitzmaurice]

I'll be embarrassed if I just missed the step of 'removing the elements' from the plans.... I just didn't see it.

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