Phase plugs?

[Wafflesomd]

So, what exactly are they, and what do they do.

 

[j_garcia]

They help smooth out response of the driver in question. Sound waves coming off the driver actually bounce off the opposite side of the driver, causing a small amount of distortion. A phase plug helps reduce this, but it entirely depends on the design of the driver.

That thing in the center of the speaker. Most notable on midrange drivers, though a few tweeters make use of them and to a smaller extent, bass drivers also (curved dust cap).

Vifa XT ring radiator tweeter:

 

[Wafflesomd]

Ok, I get it know.

 

[Sheep]

In addition to what JG said, true phase plugs are attached to the motor stucture, not the cone. They also dispate heat generated by the driver.

SheepStar

 

[Tex-amp]

As Sheep is pointing out the driver in John's picture doesn't have a phase plug but is using a dust cap made to look like one. Dust caps like that add weight to the driver and increase distortion. There should be a small gap between the phase plug and driver. If you push gently on a driver and the center stays in place as the driver moves it is a phase plug. If the center moves with the driver it is a dust cap with a marketing trick of looking like a phase plug.

Heat dispersion from the voice coil is a phase plug's biggest function. As your driving your speakers the voice coil heats up and starts to distort.

I don't think that is a phase plug on the tweeter.

 

[bongobob]

Ahhhh so that's why the phase plugs on my Studio 60's are made from aluminum. Good heat transfer. Thanks for the info.

 

[j_garcia]

Right, a true phase plug shouldn't move, but ideally, it should still serve the purpose of smoothing response. The one on the tweeter is part of the tweeter itself, so I don't think it really qualifies, but it does the same thing in terms of yeilding a smoother response. These are some very nice sounding tweeters used in some very expensive speakers. On the Studios, I believe the phase plug is fixed.

 

[ChrisJam]

What about a different kind of driver?

I've learned something from this thread.

But what about solid flat-piston drivers, like PhaseTech uses in its Premiere line? Do drivers like these have phase plugs? Do they need them?

Chris

 

[Sheep]

I've learned something from this thread.

But what about solid flat-piston drivers, like PhaseTech uses in its Premiere line? Do drivers like these have phase plugs? Do they need them?

Chris

If it looks like this

It's a phase plug.

SheepStar

 

[ChrisJam]

If it looks like this (image snipped)

It's a phase plug.

SheepStar

Thanks, Sheep!

Chris

 

[Tex-amp]

I've learned something from this thread.

But what about solid flat-piston drivers, like PhaseTech uses in its Premiere line? Do drivers like these have phase plugs? Do they need them?

Chris

All speakers are about trade offs in design. While the phase plugs allows the voice coil to remain cooler and have less distorsion you are losing surface area for bass production. I think a 6.5" driver with a phase plug moves the same air as a 5.25" without a phase plug.