Glossary


General notes on ABS pipe:

ABS Pipe (Schedule 40 in Canada at least) is an engineered product. There is a remarkable consistency between different manufacturers. It is physically strong and has a high acoustic damping factor.

The tapered female flanges of the coupling pieces hold pipe securely for a temporary fit but not so securely that pieces cannot be separated. When using ABS plumbing glue set time is extremely short. Know that you have a good fit and reherse piecing the work together quickly before gluing. Alternatively, use a glue which sets up in a more relaxed manner; epoxy would work well.


90° Tee

 

90° Elbow

 

Commonly available in 4”, 3”, 2” and 1.5” stock. Sizing of drivers and baffles is the same as for elbows. Use these elements just like the connector pieces in the old Tinker-Toy sets. 1 baffle and 2 connected pipes or 2 baffles and 1 connected pipe. Go crazy with the possibilities.   Commonly available in 4”, 3”, 2” and 1.5” stock. When sizing drivers to fit into a baffled elbow the inside diameter of the female pipe flanges is typically .5” larger than the inside diameter of the elbow/pipe stock. When sizing baffle collars or box cut-outs the outside diameter is typically 1” larger than the inside diameter of the elbow/pipe stock.

Hubcap

 

4 x 1.5 Adapter

 

Commonly available in 4”, 3”, 2” and 1.5” stock. These are for solidly terminating ABS pipe. The ABS variety are very rigid; there are some thin poly-ethelene types available but these are not rigid enough for audio use. The ABS caps have the same inside and outside diameters as all the other ABS pieces of a given size.   This gem is much more useful than first glance suggests.


With a baffle, it forms the basis for T-line enclosures for drivers 3” and under and aperiodic enclosures for drivers 4.5” and under (a short length of 1.5” pipe stuffed densly forms the vent).


Without a baffle it can be used to attach a tuned piece of 1.5” pipe to other 4” stock to make a bass reflex enclosure.

4 x 3, 4 x 2, 3 x 2, 3 x 1.5, and 2 x 1.5 Adapters


Stand in the pipe section of the local harware store and piece these together like Lego to visualize the possibilities. When a store clerk gives you static ask them if they can help you to understand the interaction of mass loading in a tapered quarter wave tube; I bet they’ll go away and leave you to play alone.


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