Phase Plug Fun

[Poultrygeist]

I bought these wooden easter eggs and bases at a local crafts store and with some glue, paint and steel washers turned them into phase plugs for my Beta 12LTA's.

http://gallery.audioreview.com/data/audio/500/medium/P5210001.JPG

[Poultrygeist]

Here I carefully circumcise the dust caps on the Beta with an exacto blade. I used a lazy susan to spin the driver while scoring the dust cap.

http://gallery.audioreview.com/data/audio/500/medium/P5200004.JPG

[Poultrygeist]

After a few turns on the lazy susan the dust cap is cut away and lifted out.

http://gallery.audioreview.com/data/audio/500/medium/P5200005.JPG

[Poultrygeist]

The steel washer glued on the rear of the phase plug is magnetically held in place.

http://gallery.audioreview.com/data/audio/500/medium/P5210005.JPG

[Poultrygeist]

Phase plugs stop "oil can resonance" which is caused by air trapped behind the dust cap. The high frequency dispersion is greatly improved as it reduces any beaming and broadens the sweet spot.

My highs are so much smoother than before I can hardly believe it's the same driver. I would think any driver with a whizzer/dust cap like the Beta's could benefit from phase plug implants.

The Betas have unseated the Tang Bands so into the closet they go.

[cackalacky]

Phase plugs stop "oil can resonance" which is caused by air trapped behind the dust cap. The high frequency dispersion is greatly improved as it reduces any beaming and broadens the sweet spot.

My highs are so much smoother than before I can hardly believe it's the same driver. I would believe any speaker with a whizzer/dust cap like the Beta's could benefit from a phase plug implants.

The Betas have unseated the Tang Bands so into the closet they go.

You got cajones!

[Poultrygeist]

Phase plugs are audio viagra.

[Poultrygeist]

I made some new phase plugs today which are much smaller and lighter but the sound is the same. Instead of a steel washer I used small countersunk wood screws which magnetically hold the plugs in place.

http://gallery.audioreview.com/data/audio/500/medium/P5250001.JPG

[Poultrygeist]

Hope I'm not wasting anyone's time with what may have limited appeal here.

[E-Stat]

Hope I'm not wasting anyone's time with what may have limited appeal here.
Well, no one has to read any post. Keep reporting what you'd like to share. On the other hand...

Do you really think that gluing a solid wooden easter egg to a driver is going to improve its HF dispersion in any consistent way - especially with whizzer cone in the way? You certainly have increased its moving mass by a significant factor which is contrary to good HF performance.

[Poultrygeist]

I know what I hear and that's enough for me. Moving mass? The plugs are not glued but held in place magnetically. They do not contact the cones or voice coil. The higher end full rangers like the whizzer cone Lowthers use huge wooden phase plugs.

Phase Plugs (http://www.centauriaudio.com.au/diy/plugs.html)

[E-Stat]

Moving mass?
Yes, that is a pretty important metric.


The plugs are not glued but held in place magnetically.
My mistake,. It is the steel washer that is glued to the wooden easter eggs.


They do not contact the cones or voice coil. The higher end full rangers like the whizzer cone Lowthers use huge wooden phase plugs.
"They do not contact the cones"? To what do they contact magnetically?

Sorry to hear about the Lowthers.

[E-Stat]

My Easter eggs look puny compared to these Lowther door knobs.
Some folks just don't understand the role of moving mass in transient response.

[Poultrygeist]

My Easter eggs look puny compared to these Lowther door knobs.

http://www.quarter-wave.com/Gallery/ML_TL_Plug.jpg

[E-Stat]

E-Stat, would you believe there's something at the rear of a speaker called a magnet?
Sure. That's the fixed motor which has to wrestle with the moving mass of the driver. High mass tweeter is a contradiction in terms.

Is there any part of moving mass don't you understand? That would be the cone, spider, voice coil and any other easter egg attached to that which moves. You really don't want adding a pile of metal and wood here.

[Poultrygeist]

E-Stat, would you believe there's something at the rear of a speaker called a magnet?

[Feanor]

I know what I hear and that's enough for me. Moving mass? The plugs are not glued but held in place magnetically. They do not contact the cones or voice coil. The higher end full rangers like the whizzer cone Lowthers use huge wooden phase plugs.

Phase Plugs (http://www.centauriaudio.com.au/diy/plugs.html)
Are you saying that your phase plugs are not attached to any moving part of the driver? I can imaging that this might be the case but you aren't making it clear.

With the dust cap, which is usually attached to the cone, removed you might expose what I believe is called the "pole piece". The latter is a fixed part of the driver; if your phase plug is attached to the pole piece, then it won't move with the cone or whizzer.

[Poultrygeist]

Feanor you get it.

All drivers I've encountered have an open throat which extends through the voice coil to the rear of the speaker. From inside the throat folks may not realize that the voice coil area appears open and cylindrical and not like a flat coil.

The large permanent ring magnet at the rear magnitzes the screen plate further down the throat which holds the phase plug's metal washer ( or counter sunk screws ) in place. There is zero cone mass or moving mass as the phase plug makes zero contact with any moving parts. You can place your fingers on these solid wood phase plugs while playing and feel no vibration.

I think E-Stat has my phase plugs confused with some pointy Dagmar dust caps. I'd recommend sacrificing an old driver for some speaker 101.

[E-Stat]

FYou can place your fingers on these solid wood phase plugs while playing and feel no vibration...I think E-Stat has my phase plugs confused with some pointy Dagmar dust caps
Only because of the claim that it improves HF dispersion. How is dispersion of the cone "improved" when the plug plays no role in radiation? I can see how diffraction might be reduced.

[Poultrygeist]

With phase plugs the cone separates into two halves which reduces wave cancellation at HF and lobbing as well as reducing hot spots which some FR drivers are notorious far.

I don't need to argue the merits of full range driver phase plugs which is a featured component among the best of the high end. It's why you won't find a Lowther or $20,000 Feastrex Field Coil without one.

[E-Stat]

I don't need to argue the merits of full range driver phase plugs .
Thanks for the explanation. Why not just start with a driver that was engineered from the start with one? Parts Express sells quite a few.

[Luvin Da Blues]

Thanks for the explanation. Why not just start with a driver that was engineered from the start with one? Parts Express sells quite a few.

Not sure if you 'mericans get this show but it's in the Red Green Manual of speaker design. :biggrin5:

[Feanor]

Not sure if you 'mericans get this show but it's in the Red Green Manual of speaker design. :biggrin5:
:lol::biggrin5: Well I get it: good one.

[Poultrygeist]

Parts Express doesn't sell a 98 db, high Qts, 12 inch full range driver with phase plugs. A.N. sells one but with low Qts which is not good for OB. That's why I have to modify what's available.

Of course if I could find one it would take the fun out of DIY.

[E-Stat]

Parts Express doesn't sell a 98 db, high Qts, 12 inch full range driver with phase plugs.
Does anyone? Just curious. Why such an unusually large full ranger?


Of course if I could find one it would take the fun out of DIY.
:)

[Poultrygeist]

Large FR's make for a humongous sound.

Walking into the room with the biggies playing is like walking into a live dance hall. Total sound immersion at low volume is a new experience for me.

I thought I loved the big Zu sound but now realize they paled in comparison.

[E-Stat]

Large FR's make for a humongous sound.
I get it.

[Poultrygeist]

Here is a good article on more driver mods and good pictures of phase plugs.

Modifying Speaker Drivers And The FF85KeN Article By Jeff Poth (http://www.enjoythemusic.com/diy/0310/modifying_ff85ken.htm)