| 2 π tower: two questions more [message #65761] |
Wed, 19 January 2011 04:47  |
tman
Messages: 23
Registered: December 2010
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Chancellor |
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I looked for these arguments within the forum, but I didn't find
anything (or I may have looked badly...).
1. Is there any tolerance for port diameter? I use metric system
and the equal value of 4" 5/8 (3/4 wood stock) is mm 117,475;
considering that I cut it handmade (with a jigsaw of course),
between which values could I fluctuate?
2. What about spikes (those cone-shaped feet)? There are people
here who spend lots of money for them, because are convinced
that sound improves strongly (especially for "drying" basses).
I read different opinions: someone says it's better using
rubber feet... What do you think about?
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| Re: 2 π tower: two answers more [message #65765 is a reply to message #65761] |
Wed, 19 January 2011 11:21  |
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Wayne Parham
Messages: 18835
Registered: January 2001
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Illuminati (33rd Degree) |
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Regarding spikes, mats or rubber feet, I do not feel strongly one way or another about them. I'm not really looking for solid coupling to the floor, nor is it important that it be decoupled. What I don't want is vibration that would cause a buzzing sound, and this can happen whether there is solid coupling or not. As long as that's not happening, the mounting mechanism isn't important to me.
As for port dimensions, it's not terribly critical. Speaker operation parameters shift quite a bit during normal use. We're looking for the Helmholtz frequency to be accurate within a few cycles. Still, this model is probably best to get as close as possible, because it's probably the most sensitive of the line.
What I would suggest is to use 18mm wood stock and make the port 115mm. If you use 19mm wood, make the port 117mm diameter. If you're using a jigsaw, you might want to cut it small, say 1mm to 2mm smaller to start with, and do some finish filing to make it round. That way you won't accidentally go too big. Where port diameter is converned, it's almost always better to err on the side of being slightly too small because that will shift the Helmholtz frequency down, which is "safer" than up.
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