passive radiator replacement problem

[BC Dave]

I have a VMPS Original passive subwoofer with a 12 inch Megawoofer and 15 inch passive radiator. I have had a problem with the passive radiator bottoming out on low movie effects (you can Google "Bottoming a VMPS larger" for an explanation), so I decided to replace the passive radiator with a beefier one from Creative Sound Solutions (CSS). The APR 15 passive has a much greater excursion capability than my older VMPS one. Long story short, I installed the CSS unit and while everything was fabulous musically, the sub now emits a metallic clanging distortion while watching a movie with low bass effects, even at a LOW volume. It actually sounds like the washers used to add mass to the sub were rattling around in the passive radiator, which of course they weren't. I will experiment with adding more of the supplied washers for mass to see if the distortion goes away. If not, do I need to purchase the correct VMPS 15 inch PR or is there another option? Thanks in advance.

 

[bikdav]

I'd leave both of those options on the table. As "unprofessional" as this may sound, would putting some soft non-metallic material between the washers quite things down? Just a loose thought.

 

[BC Dave]

Oops, duh

I feel like a double dork. I was looking up a website talking about the CSS passives and it suddenly occurred to me that the metallic sound was indeed caused by the washers rattling in the tube, because I had neglected to use the supplied wingnut and the lock washer to tighten them down. I had just tightened the cap on top. It couldn't have been the beers I had beforehand could it? Granted, there were no instructions in the box...Tonight I found the wingnut/lock washer under the whole pile of washers and cranked that mother down. The results were instantly fantastic. My son and I put on the Green Hornet and boosted the volume. The sub pounded out the bass with nary a stumble. Very happy with the CSS passive. An incredible $67 (sale price sigh tax) improvement!

 

[bikdav]

Don't Feel Bad

That's great. I'm glad that it all worked out for you. That does not qualify in any way for the "dork factor". Things like that happen to me a lot. Sometimes, walking away from a problem for a little while and reattacking it later makes all the difference in the world.

 

[caper26]

What exactly did the "bottoming out" sound like???

 

[BC Dave]

bottoming out

It sounded like the sub was coming apart at the seams. Gross distortion, even at a low volume, on deep movie bass. With the new passive radiator there is none of that.