prevent the chuffing? phase plug??

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rick57

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Most big woofers chuff and puff quite audibly when you don't have a box to hide the noise, ie dipole.

Lambdas supposedly don’t chuff when used with the aluminum phase plug.

How easy would that be to make a suitable phase plug, or otherwise prevent the chuffing?
 
Paul W

Paul W

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geocities.com/pnwright3/WINGS_low_diffraction_C-Baffle_WTW_ribbon_mid_tweeter
There are several possible sources of low-frequency noise. One is the pole vent (if one is used). One way to reduce air compression inside a woofer without a vent is increasing the internal air volume behind the dust cap (which can be shaped like a phase plug). I do not know if the Lambda phase plug is hollow and attached to the cone or is if it solid and attached to the pole (like Seas).

John at Stryke now has the parts to produce the original Lamda dipole woofers. Those drivers have the phase plug, low VC inductance, plus a Faraday ring/sleeve for lower distortion. If I wanted to cross a large driver above 100Hz, those would be some of features I'd be looking for.

my dipoles
 
Paul W

Paul W

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geocities.com/pnwright3/WINGS_low_diffraction_C-Baffle_WTW_ribbon_mid_tweeter
Many more differences than the phase plug...underhung VC etc etc. Here's a link to the Lambda specs.

link to Lambda specs

John told me he now has the components (from Nick) to build anything in the Lambda line. I wanted some "just in case" I thought of the perfect application...but can't justify it...already too many idle drivers in closets, garage, basement, etc :(
 
Ron E

Ron E

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Joined 2002
rick57 said:
Most big woofers chuff and puff quite audibly when you don't have a box to hide the noise, ie dipole.

Lambdas supposedly don’t chuff when used with the aluminum phase plug.

How easy would that be to make a suitable phase plug, or otherwise prevent the chuffing?
Click to expand...


The reason the lambdas wouldn't chuff with a phase plug is that the phase plug would remove the possibility of air trapped behind the dustcap that would be forced through the pole vent. This would reduce cooling air through the pole piece and thus teh phase plug would be needed to wick heat from teh woofer at higher powers.

At such low frequencies, the phase plug shape would be unimportant, you could just use a slug of aluminum the same diameter as the pole piece with an interference fit into the pole vent. Remove the dustcap and you would have a noiseless driver....perhaps with a bit less powerhandling and with no warranty....
 
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rick57

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Joined 2002
Ron

That makes sense. Without having seen the driver, and personally having no metalwork skills, I wonder how easy it would be to attach a
“slug of aluminum the same diameter as the pole piece, with an interference fit into the pole vent”?

What’s an interference fit?
 
Ron E

Ron E

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Joined 2002
An interference fit is a method of essentially forcing a shaft which is ever so slightly bigger than the hole into a hole such that the coefficient of friction between the two parts is enough to keep them together. Alternatively you could use a looser fit and glue the phase plug onto/into the pole piece.
 
R

rick57

Member
Joined 2002
Hi Paul
(Only just saw your post). It’s for a dipole covering 60 – 280 Hz on a small baffle.

I was intending to use the XLS 12, but was originally concerned it wouldn’t go to 280 Hz; but since then an experienced builder has convinced me it will (though not too much further).

Now, based on good advice from the Yahoo dipoles group, I’m thinking it may not have enough Vd, and will check the cost of a pair of TC2+.

Thanks

Richard
 
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