P-6.5 passive membrane 17.5 cm / 6.5" with variable weights

Passive radiators are a better solution than bass reflex ports. The P-6.5 passive radiator fits 1 x 17.5 cm Ø, 1 to 4 x 10 cm Ø and 1 to 2 x 13 cm Ø loudspeakers.
Furthermore, a 20 cm speaker can be combined with 2 x P-6.5 drivers. Outer diameter 179 mm, mounting hole 145 mm.

The main advantages are:
1. No space problems with reflex tubes in compact housings and no flow losses.
2. No pipe/breathing sounds
3. No midrange frequencies are unwantedly emitted to the outside.
4. The P-6.5 is tunable via 3 removable weight plates.

The hard-anodized aluminum membrane weighs 20 g. The three discs each weigh 20 g and can be removed. To do this, use long flat-nose pliers to turn the rear nut counterclockwise.
DANGER:
The screw at the front and the nut directly on the back of the diaphragm are glued in place - please do not remove them!
The effective diaphragm weight can now be adjusted using the 3 discs. For particularly fine-tuning, one disc can be made smaller or other weights can be screwed on.
When tuning by ear, you first test with 3 discs to determine which one suits our D-165 subwoofer speaker driver. This configuration corresponds to the very well-reviewed Hobby HiFi ULTRA-SUB. For further improvement with DSP, we recommend our DSP-6mini, which, with its 3 stereo channels, can also control the midrange and treble frequencies (link). For lighter and smaller drivers, reduce the number of discs until the deep bass sounds best.
When tuning based on measured impedance curves, both impedance maxima should be the same height.
10 cm speakers are combined with P-6.5 without a disc, 1-2 discs fit 13 cm speakers and lighter 16 cm diaphragms.
Rule of thumb:
Heavy passive radiators = balanced and deeper bass - lighter passive radiators = louder, but not as deep bass.
For 2-3 weight plates, we recommend rotating the P-6.5 by 180° every year to ensure a more even load distribution on the rubber surround.