DIY圆柱低频陷阱分享

v606 · 发表于 2012-2-6 17:04

回复 10# 毛林
不是按这个图样做的，我参考的是这篇文章：
Instructions for cylindrical bass absorber
Tools needed-
• Caulking gun (for adhesive)
• Staple gun
• Pins (sewing)
• Scissors
• Razor knife
• Not very much talent!

You will locate the tube material at any industrial heating and cooling outlet. There are three or four brands, but the tube is used as the insulation cover of heating and cooling pipes. The brand I found in my area is Knauf fiberglass pipe covering. They come in assorted sizes, just remember that the specified size is the INSIDE dia. of the tube. IE- A 10 in. tube wraps around a 10 in. pipe. With the 1" thickness of the tube, the outside diameter would be 12". The tube is compressed fiberglass, and is 1 in. thick. They come stock in 3 ft. lengths. A rough rule of thumb is 10-in. tube will absorb down to about 70 Hz. 20 in. tube to around 40 Hz.
The tube comes wrapped in an aluminum/paper backed wrap. This layer will become the reflective wrap of the absorber. DO NOT REMOVE YET!

From a small sheet of 3/8-in. drywall, cut circles the same size as the outside diameter of the tube. These are the top and bottoms. You can use wood, but drywall is easier to work with. All you need is a surface to glue on and that will hold staples.
The tube is split on one side so as to put around pipes. Prop the tube open and run a nice thick bead of adhesive (Liquid Nails etc.) along the vertical edge. The paper covering has a peel back adhesive paper lip that holds the tube closed while it dries. Run a bead around the top. These beads MUST be gap free. The tube MUST be air tight for it to be effective. Place the drywall circle on the top with a slight turning motion to ensure the adhesive is gap free. Repeat on the bottom. Place a couple of books on it overnight to cure.
Above and right I have dismantled one for show.You can see the glued on drywall with half of the tube covered in the supplied paper. The side with the paper showing is the front, for diffusion. The side showing the raw tube is the absorbent side. Here also you can see the rear of the fabric just folded over and pinned. As it faces the corner, it will never be seen.
I needed to match the fabric to the traps that I already owned, so I tracked down Guilford. They can be reached at-
Guilford of Maine
Textile Resources
5300 Corporate Grove Dr. SE
Suite 200
Grand Rapids, MI 49512-5512
1 800 544 0200
The Crème color ASC uses is called Quartz, FR 701, Style 2100, #380. You can order it custom cut for a couple bucks more.
Don't get caught up in finding a fabric that you think has to "breath" like open weave burlap. (Ugly!) Bass does not travel in waves, it behaves as pressure. (If bass can go right through a flimsy wall, it will certainly go through a piece of fabric!)
When the trap is dry, cut half of the diameter paper off. I cut off the side away from the seam. Now one side is reflective, the other, absorptive.
Cut the fabric so it overlaps the ends of the tube about three inches each end. Wrap the fabric around the trap and pin down the seam. Don't worry about getting it super tight now, you will get it tight when you staple the top and bottom. Fold the fabric over top and put a couple of staples to hold it. Directly in line from that, pull the bottom tight and staple. Work your way around, alternating top and bottom. Make sure you decide which way you want facing outward before you wrap it. IE- the side that faces the wall will have the seam, unless you care to sew the seam. (Good luck!)
Below are two shots of the finished absorbers. Once stacked, you don't notice
the ends.

If one is a little handier than I, you could make some fancy wooden end caps to finish them off. Or I have also thought of using the thin counter top veneer end pieces that could wrap around as a "seam", and then fastening them at the rear. I have also looked for sized matched plastic flower pots! But no luck yet.
I stopped at this point. If anyone takes this a step further, please drop me a note with the details.

v606 · 发表于 2012-2-6 17:06

毛版的这个图样虽然容易实施，但具体效果没有经过试验，心里没有谱

毛林 · 发表于 2012-2-6 17:34

有不少资料介绍低频陷阱的，有平板的，有三角，有圆柱，但是几乎没有哪个有具体的计算方式，依葫芦画瓢要烧钱的，没有尝试过，我一只在找有依据的方式，有一款可调的方式有计算方式，没试过。

毛林 · 发表于 2012-2-6 17:37

像这种虽然说的有模有样多150-300有吸收作用，但是没有计算依据，除非做一个试试，这会花费很多时间和精力

v606 · 发表于 2012-2-6 19:25

回复 15# 毛林
上面的资料曾经看过，确实是除了穿孔板吸声结构可以计算外，其他都没有提供计算方法，难以准确控制效果。三角形陷阱一直在使用，对100Hz左右频率的吸收效果不错，但不是按上面的资料做，用的是SuperChunk法。
平板吸声器这两个月试用一下看看效果如何，按原理看低频吸收效率应该比SuperChunk法差，这个等现场使用测试后再谈，毕竟纸上谈兵有点不负责任{:6_173:}