Phase Plug?

[gedlee]

And they can greatly contribute to the driver’s performance. The Visaton B200 is an example of a drive rthat hugely benefits.

Can you show us some of the data? Before and after. I've never really understood the concept.

 

[planet10]

Nope.

The B200 has a signifivcant rise in response as frequency goes up and highest fequencies are like a laser beam.

Subtracting the dustcap abd adding the phase plug flattens the response and greatly improves dispersion higher up, no laser beam.

dave

 

[gedlee]

But no graphical data?

 

[planet10]

No.

dave

 

[rhythmsandy]

My latest project, 4" aluminum phase plugs for BMS 18" woofers:

An externally hosted image should be here but it was not working when we last tested it.

']https://i817.photobucket.com/albums/zz95/LegisActio/BMS 18 inch woofers/Phase Plugs/Plugi1_zpsab9b5856.jpg[/IMGDEAD][/URL]

An externally hosted image should be here but it was not working when we last tested it.

']https://i817.photobucket.com/albums/zz95/LegisActio/BMS 18 inch woofers/Phase Plugs/Plugi5_zps876e0d0d.jpg[/IMGDEAD][/URL]

An externally hosted image should be here but it was not working when we last tested it.

']https://i817.photobucket.com/albums/zz95/LegisActio/BMS 18 inch woofers/Phase Plugs/Plugi3_zps82822f6f.jpg[/IMGDEAD][/URL]

An externally hosted image should be here but it was not working when we last tested it.

']https://i817.photobucket.com/albums/zz95/LegisActio/BMS 18 inch woofers/Phase Plugs/Plugi2_zpsa4761239.jpg[/IMGDEAD][/URL]

An externally hosted image should be here but it was not working when we last tested it.

']https://i817.photobucket.com/albums/zz95/LegisActio/BMS 18 inch woofers/Phase Plugs/Plugi4_zps6adceea5.jpg[/IMGDEAD][/URL]



The phase plug goes partly in the shorting ring that sits on top ot the pole piece and they form electrically and thermally one piece. Each plug weights ~2.8kg, they dissipate heat and act as a heat buffer.

BMS woofers have triple shorting ring motors, so the plug did not reduce inductance at the VC's resting point but I think it linearizes inductance (Le(X)) as the higher order harmonics (>H3, also H3 reduced here and there) reduced nicely in the middle and upper bass area.

On the right is the phase plugified woofer (look for ex. at the pink, blue and orange lines between 50hz and 200Hz). Measurement distance ~65cm, woofer was in 36cm deep U-frame baffle. The woofer is BMS 18N850, neodium motor (modified cone and damped basket).

An externally hosted image should be here but it was not working when we last tested it.

']https://i817.photobucket.com/albums/zz95/LegisActio/BMS 18 inch woofers/Phase Plugs/THDcomparison_zpsbea0e390.png[/IMGDEAD][/URL]

Couple of sine tone comparisons, the phase plugified is on the right again:

An externally hosted image should be here but it was not working when we last tested it.

']https://i817.photobucket.com/albums/zz95/LegisActio/BMS 18 inch woofers/Phase Plugs/100Hz_comparison_zps6ce39bc9.png[/IMGDEAD][/URL]

An externally hosted image should be here but it was not working when we last tested it.

']https://i817.photobucket.com/albums/zz95/LegisActio/BMS 18 inch woofers/Phase Plugs/130Hz_comparison_zpsc3703a7e.png[/IMGDEAD][/URL]



Above pictures in numbers:

100Hz:

Without phase plug / With phase plug / Difference
H3: 0,153% (-56,3dB) / 0,100% (-60dB) / -3,7dB
H4: 0,0201% (-53,4dB) / 0,288% (-50,8dB) / + 2,6dB
H5: 0,166% (-55,6dB) / 0,0771% (-62,3dB) / -6,7dB
H6: 0,0155% (-76,2dB) / 0,0123% (-78,2dB) / -2dB
H7: 0,0702% (-63,1dB / 0,0207% (-73,7dB) / -10,6dB
H8: 0,0098% (-80,2dB) / 0,0096% (-80,4dB) / -0,2dB
H9: 0,0332% (-69,6dB) / 0,0123% (-78,2dB) / -8,6dB

130Hz:

Without phase plug / With phase plug / Difference
H3: 0,262% (-51.6dB) / 0,0970% (-60,3dB) / -8,7dB
H4: 0,0287% (-70.8dB) / 0,0111% (-79,1dB) / -8,3dB
H5: 0,284% (-50,9dB) / 0,125% (-58,1dB) / -7,2dB
H6: 0,0345% (-69,2dB) / 0,0191% (-74,4dB) / -5,2dB
H7: 0,0936% (-60,6dB) / 0,0360% (-68,9dB) / -8,3dB
H8: 0,0276% (-71,2dB) / 0,0067% (-83,5dB) / -12,3dB
H9: 0,0107% (-79,4dB) / 0,0037% (-88,6dB) / -9,2dB

These are quite good numbers. The Image links are broken are not visible can you repost them please.

 

[Arez]

These are quite good numbers. The Image links are broken are not visible can you repost them please.

You know your asking for pics from a 11 year old thread?
posts you inquired about is from 2013🙂

 

[rhythmsandy]

whatever it was good info and I would have done the same.

Overall the phaseplug is reducing the distortion as well even at extreme low frequency is a plus point. I have simulated and seen the difference of spl drop because of phase plug is about 0.5db for a 50mm voice coil for an 8 inch and 10 inch is abit more lower reduction.

Low freq distortion is one of the most complicated distortions to eliminate. So here if you observe the reduction of certain harmonics are beyond 10 and 12db which is excellent especially the H7 which is very nasty harmonic and not pleasant to ears.

I got my conclusions like said in the previous replies.

 

[Paulo Batista Gomes]

Hi Dave,
I would like to know please, do you have phase plugs for the "Coral Flat 8 II"?
Paulo

 

[planet10]

Not officially, what is the VC diameter?

dave

 

[Paulo Batista Gomes]

Thank you Dave,

It looks like a diameter of 28mm, but I will need a tool to measure it correctly.