Magic Speakers!

Guest2 · 5 Jan 2010 at 19:54

I have some B&W 603 S1 Speakers. I took the midrange out, followed by the sub. The sub however is not connected to anything! Nothing at all, it just slots into the space, screw in and then it works.

On the crossover there is one clip wire for the tweeter and red and blue clip wires for the midrange. Nothing else

Does the air from the midrange speaker push against the bass cone and create the bass? However the bass driver seems to vibrate too much for it to be just air.

How does it work?

Dr.EM · 5 Jan 2010 at 20:06

What you have in your hands is indeed a "passive radiator". Isn't there a port on these speakers as well though? If so, that is a seriously strange design, as the passive radiator is used instead of a port!

EDIT: http://en.wikipedia.org/wiki/Passive_radiator_(speaker)

Guest2 · 5 Jan 2010 at 20:18

The port is just below this "passive radiator" thing that i have never heard of! (on the front of the speaker)

Dr.EM · 5 Jan 2010 at 20:26

Very strange, the B&W archive for this speaker says that it uses both and you can balance the tuning using foam bungs in the port. Is there some type of internal divider between the ported section and the passive radiator+midwoofer section? It must effectively act as a double bass reflex design, but with a PR instead of the first bass reflex.

Guest2 · 5 Jan 2010 at 21:29

there is a bit of an internal divide, but not much... I had another reply on avforums...

There will be a frequency at which this device resonates, just as the port in a bass reflex speaker has a resonance. At the frequency, the bass is re-enforced. At all frequencies above that point, just as with bass reflex, the passive radiator simply 'softens' the air inside the cabinet and increase the general efficiency of the speaker.

In short, it is just a glorified bass reflex port.

Dr.EM · 5 Jan 2010 at 22:16

A passive radiator is just an alternative for a bass port yes, with some advantages and some disadvantages. The thing which is unusual is the use of both the PR and the port, I've not seen that before. It's not even an option on my speaker modelling software!

Guest2 · 5 Jan 2010 at 22:33

Dr.EM said:
A passive radiator is just an alternative for a bass port yes, with some advantages and some disadvantages. The thing which is unusual is the use of both the PR and the port, I've not seen that before. It's not even an option on my speaker modelling software!

Therefore I must have magic speakers! At least the sub cone hasnt/cant burn out then. Its suprising how much it moves to say its not powered. I currently have the volume on 8 o clock and can clearly see it moving

danza · 6 Jan 2010 at 00:27

Guest2 said:
At least the sub cone hasnt/cant burn out then.

Yeah it has. Looks to have taken all the wiring out with it too. I'll give you 50 quid for the speakers.

I've never noticed speakers with a reflex port and passive radiator aswell. Interesting!

Usually tweeters go pop before bass drive units anyway, so I was a bit confused when you posted that the woofers were dead in your first thread about these speakers.

Guest2 · 6 Jan 2010 at 08:55

danza said:
Usually tweeters go pop before bass drive units anyway, so I was a bit confused when you posted that the woofers were dead in your first thread about these speakers.

no doubt some tool was playing the best of dubstep remix or something like that off youtube. cue the midrange driving getting a little too hot. (its black)

Next house party im just going to limit volume in windows to 15% and wack a proxy on internet so it wont work

edit - note for people taking speakers to bits - Don't try and pick your speaker up by the bottom when you use speaker floor spikes. I now have a hole/cut on my hand which is quite deep