prevent the chuffing? phase plug??

[rick57]

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?

[Bill Fitzpatrick]

My woofers don't chuff despite the front of the cone not being in an enclosure. What does the chuffing/puffing sound like?

[richie00boy]

Chuffing as you describe it is a result of turbulence around the basket/frame. Nothing to do with phase plugs, which are for mid/high frequency.

[rick57]

richie00boy

It was a quote off another forum. I thought that too, after I wrote it.

How easy would it be to otherwise prevent turbulence around the basket/frame??

[Paul W]

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

[rick57]

Paul

Sounds like the only diffrence from other 'midrange' Lambdas may be the phase plug.

Do you know if either the dipole or the others has a pole vent?

I can't see John's email on the Stryke site yet. Do you have it?

BTW, nice work Paul!

[Paul W]

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]

Originally posted by rick57
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?

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....

[rick57]

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]

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.