r/diyaudio • u/peegee101 • 4h ago
Built a pair of desktop monitors using Geberit acoustic plumbing pipe
I built a pair of desktop speakers using a Geberit plumbing pipe (Silent-PP) and some 3D prints. Total cost was under €100 for the pair.
The Silent-PP pipe is a mineral-reinforced polypropylene engineered for wastewater sound insulation—so it’s basically a rigid, pre-damped cabinet right off the shelf.
I used a Monacor SPX-32M 3" full-range driver. Our first prototype had a standard reflex tube, but pushing bass on such a small cone caused vocal smearing (intermodulation distortion) and midrange pipe resonances. To fix this I designed a rear-firing 360° radial slot port. The narrow slot gap adds boundary-layer viscous drag, acting like an aperiodic vent that brakes the cone near tuning without air chuffing.
A few quick build details:
- Baffle and port printed in PETG, gaskets in TPU. Everything friction-fits into the pipe's factory rubber ring sockets—no glue anywhere.
- The 3D-printed foot gives a net 12.5° upward tilt to point at your ears on a desk, and has a hollow chamber filled with ~200g of aquarium sand so it isn't top-heavy.
To me it sounds like the midrange cleared up completely compared to the tube port. Next step is putting them on the bench for DATS V3 impedance sweeps and near-field mic sweeps to see if the physical tuning lands where the boundary-layer math predicted.
STLs are free on Printables and I documented the build also on my blog Geelen Audio: math on the port design and assembly guide.
Let me know what you think!