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Peerless 830878 3-1/2" Passive Radiator
Comparable to what size port?
What size/length port would this PR be comparable too? Can you recommend any sites/software that can be used to calculate enclosures using small fixed PRs like this? Usually with larger ones you can adjust the mass to taste, but with this little guy you've got to be spot on.
It's hard to compare really.With a port you can keep pushing more air, you are just forced to do it faster. As a result, port air velocity will go up until you start getting port noise (chuffing, whistling) which is undesirable.With a passive radiator, you are limited in volume, where the maximum volume of air (Vmax) to be displaced is Vmax = Sd * Xmech * 2. There is no "port noise" with a passive radiator; instead you might notice some mechanical noise due to the internal moving parts, specially when near the unit's mechanical limits.As for sizing, I'd suggest using an active speaker no larger than the passive radiator itself... so a 1:1 ratio as a minimum. For subwoofer application, you would typically see a 12" sub paired with 2 12" radiators, but that is strictly a subwoofer. I think something like this is more suitable to extend the low end of a full range speaker.As for adjustable mass, I would think it would be adjustable. Just doesn't make sense to have it be non-adjustable. Can we get an answer to this? Anyone else...
Date published: 2012-07-25
Xmax? Can you add weight?
I want to winISD this piece and need to know the Xmax. Knowing the thread size would also be helpful if it does, in fact, accept added weight.
Xmax is the maximum peak linear excursion of driver in mm.passives have a parameter name ,,, i just cant seem to recall what it is...if your concern is the radiator not having enough excursion against the active driver, you shouldn't be.Passive radiators generally surpass peak excursion by far and i personally never witnessed one that did not, OEM brands included.TIP:Epoxy Fender washers to center of dome for weight,,,, its cheap, effective and works....
Date published: 2014-01-23
What's the rms ?
How many watts can this pr handle?
RMS is the power rating for anything you wire. Not a passive device such as this.
Date published: 2014-03-24
I would like to bring the Mms up to 45 grams?
Are there any charts that would point me in the right direction as to how much weight to glue on? Any shortcuts would be appreciated. Buying a second PR seems excessive, and wont result in Mms 45g.Otherwise I suppose I could place talcum powder on it and play with a test frequency until I get my enclosure tuned right, but is there a better way that requires less trail and error/profanity?
The moving mass of this radiator is 38.5 grams from the factory, so you simply need to add 6.5 grams to the rear of the cone.
Date published: 2014-03-24
How do i tune this passive radiator ?
Weight is to be added to the back of the cone or dustcap by gluing washers or other small weights to it.
Date published: 2014-02-12
Can I use these to extend/increase low frequency output of a full-range 6x9 in a small, sealed enclosure? Would multiples improve lower frequency response vs. just one, such as to supplement 60-80hz range?
I would not recommend a passive this small to be used with a 6x9. Something like our 8" Dayton would be a better choice although I cannot model the box volume or tuning frequency without driver specs.
Date published: 2014-03-18