Should I use a Bass Reflex Tube (?) or a Passive Radiator for my speaker?

[vascobrissos14]

Hey, I'm building a 20W speaker (10Wx2) and I have a "tube" an old audio system.
This kind of thing (https/www.cybermarket.co.uk/images/product/main/12.8650.jpg)

But I saw a video where they used a membrane that I heard that it is a passive radiator.

And it got me thinking, should I use the tube or something like this?
Ebay link: http/www.ebay.com/itm/Black-3-Square-Passive-Bass-Radiator-Woofer-Radiators-Passive-Speaker-3x3x1-1-/131912316761?hash=item1eb6963759:g:mB8AAOSw6n5XtYSR

And I came here to ask for help to decide which one is the best, if a tube that I have or this passive speaker. I heard it has many advantages but I never heard of it and don't know what it does. Does it add bass? Tell me please
The speaker will be somewhat like this http/prntscr.com/drlwep

Thank you if you can help me

PS: does the passive speaker/radiator go in the front or the back? If so tell me where the best place is so I can change the case schematic. TY

 

[jsmithepa]

Surely, there is a whole library that goes into speakers building with all the plus and minuses, you can find on the web.

If I recall correctly: Sealed speakers give you more accurate, tighter sound at the expense of less power, Bass Reflect gives you max power sacrificing accuracy, and a passive radiator is like compromise between the two extremes. That's all I can remember.

 

[vascobrissos14]

Surely, there is a whole library that goes into speakers building with all the plus and minuses, you can find on the web.

If I recall correctly: Sealed speakers give you more accurate, tighter sound at the expense of less power, Bass Reflect gives you max power sacrificing accuracy, and a passive radiator is like compromise between the two extremes. That's all I can remember.

I see. My dad told me that sealed speakers are bad since they can "explode" for air being closed. He has always told me to make some holes to let the air pass circulate.

But from your response I think I should buy a passive radiator and use it on the middle of the active speakers. What do you think? Ty

 

[nitsuj.plop]

Surely, there is a whole library that goes into speakers building with all the plus and minuses, you can find on the web.

If I recall correctly: Sealed speakers give you more accurate, tighter sound at the expense of less power, Bass Reflect gives you max power sacrificing accuracy, and a passive radiator is like compromise between the two extremes. That's all I can remember.

I see. My dad told me that sealed speakers are bad since they can "explode" for air being closed. He has always told me to make some holes to let the air pass circulate.

But from your response I think I should buy a passive radiator and use it on the middle of the active speakers. What do you think? Ty

Keep in mind that when using a passive radiator you should always seal your system as good as possible, so that you have a high air pressure and the passive radiators can do their job best. I would add per 1 speaker 1 passive radiator with similar or bigger size. It doesnt matter that much where you put them, however i experienced: For less destortion put them across from the speaker, for more bass at the same side as the speaker, for smth. in the middle put them on the sides (like JBL does it with their bluetooth boxes). The differences are very little to not noticeable.
I hope i could help a little out.

 

[BFG-9000]

The tube is a lot easier to tune than a passive radiator, but tends to sound more like a single note so all the bass sounds the same.

See, the whole point of either is to delay the waves from the rear of the speaker until they are in the same phase as the front, so it's louder. Obviously the sound coming from the rear of the speaker is exactly out of phase from the front, so if you hang the speaker in free air without a cabinet the out-of-phase frequencies combine to cancel out (destructive interference) and you get no bass. With random holes in a cabinet you get certain frequencies that are lost.

With the tube you can simply cut the length by trial-and-error until the frequency you are trying to emphasize is loudest. With the passive radiator (which is essentially a speaker with no voice coil) you have to hope your original calculations were correct as it's near impossible to move the hole for it so you are stuck trying to add baffles inside the cabinet.

The sealed box is easiest to get right and has the highest damping so bass sounds tightest, but the two ported designs are far more efficient, which means louder for the same wattage. At least for the frequencies it's tuned for.