Adding passive radiators to sealed bookshelf cabinets

[Onebigski]

For me it's a myth that a PR is the solution for bass reflex in a small box. Especially if it should be tuned very low

It won’t be tuned low, I’ve got powered subs for that. I just want to see if I can hear a difference.

 

[Onebigski]

Best is to put the PR on opposite sides of the box for cancelation of the vibration. Like in boxer motors

#1 Comment of the post! For including a motorcycle reference. I’m a big GS fan. And that’ll be how I do it if I can get around my newest problem. My PRs were not flat when removed

 

[Onebigski]

The magnets don’t move, just the cone so the combine weight of both PRs vibrating with weights in them, would be significantly more

 

[Onebigski]

No, it's some time ago. Had problems tuning in 8 liters a 8 inch PR down to 30 hertz. Adding a lot of weight to a PR is critical and the vibration of a heavy mass exerts vibration to the box, too.

http://mh-audio.nl/Calculators/PassiveRadiator.html

Well here is a direct comparison side by side as well as a visual of the weight in the PR but now I have a different problem. I’m not sure the PRs come apart with a flat surface to mount to the box. Also, the bolt holes are the same size but the replacement speaker itself is slightly smaller so there’s a gap, which means I’ll have to build a spacer to seal it off. I’m tempted to pull apart the Klipsch to see if they fit better but I really like the look of that centre post and in stock form, these Definitive Technology speakers sounded really good.

 

[russc]

Just curious - have you tried rotating the original rubbing drivers?

 

[Onebigski]

No I haven’t tried that, and now that I’m half way into the project, I may see if that works if I keep the old drivers. I’ve got a friend with a 3D printer that is going to make the spacers for the new drivers to sit on so seal the holes from the ever so slightly larger original drivers.