Passive radiator or sealed box

[Richard_James]

Looked around a bit.
Few things are still confusing

Cons

1) passive radiator seems to be moving out of phase with active woofers

2) passive add floppy and muddy bass at a narrow frequency range that they re tuned for


Pros
1) better than ports.

But jn general if u don't want a bass boost but just an accurate music reproduction a sealed system is best right?

 

[Inductor]

The BR takes better use of the potentialities of the drivers.
You use PR (passive) when port is not adequate.
A sealed enclosure is good with less delay, more accurate but as the others needs different drivers. One drivers for each application (BR or PR vs. sealed).

 

[rayma]

1) passive radiator seems to be moving out of phase with active woofers
2) passive add floppy and muddy bass at a narrow frequency range that they re tuned for
1) better than ports.
a sealed system is best right?

1) Only at the lowest frequencies below resonance.
2) Yes, it's a resonance.
1) Yes, a little.
Yes, if well designed.
The aperiodic approach invented by RCA works very well, but is seldom used.

 

[Richard_James]

I see. What if I have a set of speakers that have a passive radiator and just seal it with a piece of wood.
Actually I am planning to build all new boxes for the speakers

It's Polk sda-crs+ . Sda-crs+(compact reference series) have 2 active woofers , one 10" passive radiator and one tweeter.
There is also Polk sds-srs 2b which is the same exact components (woofers cross overs tweeter) except it has 12" passive radiator.
And cabinet 2.5 times the size of small sda-crs+
Overall I like the speakers. Huge stage.
They seem to play 30-40hz band pretty loud. Then it's a void. 40-50hz not much audible. And then 50hz+ everything plays fine

I ideally want the drivers to play 50hz+ or 60hz+ but accurately.. eliminate extra movement to make bass. I have a sub

Would making a sealed cabinet of same size achieve this? Not a ton of information on the drivers used in those speakers but I think I have some theil specs for them. Fs, xmax etc

 

[rayma]

Your driver may not be well suited to a sealed box design, but if it were, it would likely need a smaller box
volume for best results. You could experiment by adding bricks inside to reduce the internal volume,
and sealing the PR opening.

 

[Richard_James]

Your driver may not be well suited to a sealed box design, but if it were, it would likely need
a smaller box for best results. You could experiment by adding bricks inside, and sealing the opening.

Interesting. I did play around with winisd. And it did give me smaller size than original boxes.

I'll post all info about drivers and original boxes when I get home.


One other question. Say each of the drivers has a compliance volume of 30liters. Does this mean I need to have box volume of 60 liters if both of those drivers are sharing the same box. I am planning to make separate sealed compartment for each if the drivers

 

[rayma]

Yes.

 

[Nenola]

Have you actually measured your speakers in open space to confirm, that the inaudible 40-50hz comes from poor speaker design?

Of course you might get good results with modifying the speakers, but if the reason for inaudible frequencies is your room acoustics, you are fixing the wrong things.

 

[Richard_James]

I just played frequencies from youtube. 5-200hz

Here are the graphs
I can use either 6503+6502 drivers
Or 6503+6511 drivers

The curves that are almost identical are 6503+6511
6502 seems like an inefficient driver. Lower curve

I want tighter mid-range

I'll play speakers in open space in few days to confirm 40-50hz dip in frequency response.