Why don't subwoofers utilize phase plugs?

[T.I.K. 10+ year member]

Read the title.

Wouldn't it make sense to keep mms down? Especially on SQ woofers?

Click to read more...

 

[gckless 5,000+ posts]

Also interested in this.

 

[zako 10+ year member]

Based on everything I have read so far, simply on its own MMS seems pretty much insignificant parameter. There have been some variations on this theme, some people saying that MMS does not matter, but BL/MMS does or BL squared/MMS does. And then there was a widely discussed paper posted on Adire Audio web site alleging that they have done an experiment that MMS has nothing to do with subwoofer's transient response, and the inductance is very important, or something like that. Of course, there are also many counter-examples to the statement "high or non-linear inductance is bad for SQ" as there exist highly regarded for SQ subwoofers, such as Image Dynamics or JL Audio ones, without inductive treatment.

Whatever the truth is, one thing I learned is not to make blanket statements like "Low MMS is good" or "high BL is good" (Nonetheless, I still consider inductance behavior as a factor when selecting a subwoofer, but I can see myself buying a sub with no inductive treatment if others say it sounds good).

Next onto the phase plugs.. two things I heard about them is that they

1. Help with cooling, specially when they're made with metal (instead of plastic or wood)

and

2. They can reduce the effects of beaming, which seems irrelevant in case of subwoofers (I don't care if my sub is beaming at 300Hz or 400Hz or whatever).

On the other hand, you lose a bit of cone area to the phase plug, which seems important to the subwoofers. Also, with a phase plug, you no longer have a perfect seal between the interior air and the exterior. All of this as well as the fact that I haven't seen subwoofers with a phase plug suggests that they're not that important or useful.

I am waiting for a good response too, hopefully from someone like from sundownz.

 

[T.I.K. 10+ year member]

[quote name='zako']Based on everything I have read so far, simply on its own MMS seems pretty much insignificant parameter. There have been some variations on this theme, some people saying that MMS does not matter, but BL/MMS does or BL squared/MMS does. And then there was a widely discussed paper posted on Adire Audio web site alleging that they have done an experiment that MMS has nothing to do with subwoofer's transient response, and the inductance is very important, or something like that. Of course, there are also many counter-examples to the statement "high or non-linear inductance is bad for SQ" as there exist highly regarded for SQ subwoofers, such as Image Dynamics or JL Audio ones, without inductive treatment.

Whatever the truth is, one thing I learned is not to make blanket statements like "Low MMS is good" or "high BL is good" (Nonetheless, I still consider inductance behavior as a factor when selecting a subwoofer, but I can see myself buying a sub with no inductive treatment if others say it sounds good).

Next onto the phase plugs.. two things I heard about them is that they
1. Help with cooling, specially when they're made with metal (instead of plastic or wood)
and
2. They can reduce the effects of beaming, which seems irrelevant in case of subwoofers (I don't care if my sub is beaming at 300Hz or 400Hz or whatever).

On the other hand, you lose a bit of cone area to the phase plug, which seems important to the subwoofers. Also, with a phase plug, you no longer have a perfect seal between the interior air and the exterior. All of this as well as the fact that I haven't seen subwoofers with a phase plug suggests that they're not that important or useful.


I am waiting for a good response too, hopefully from someone like from sundownz.[/QUOTE]

I mean, I understand that there's probably a good reason they're not used on subwoofers, I just want an explanation.

@sundownz

 

[blobb454 10+ year member]

//content.invisioncic.com/y282845/emoticons/graduate.gif.d982460be9f153bb54e5d4cb744f6ae8.gif waiting to learn here.

 

[sundownz Pro Seller]

The main benefit is to increase off-axis response and/or to otherwise shape the response on midrange drivers; which is exactly what zako stated.

On a sub-woofer you would *decrease* your cooling (the dust cap is the cover of the air pump after all - without the cap air doesn't pump through the pole vent or internal gap at all) and decrease your SD by the amount of the pole. Also... you are opening an air-leak directly into your enclosure ; even more so on drivers with vented gaps (air directly from the box could come out, through the gap, and out around the phase plug). Also you would open up the gap for debris, especially in car audio, hence the term "dust cap"

 

[dragonrage 10+ year member]

Yeah, they have very little effect on larger waveforms (lower frequencies) because they are TINY compared to bass waveforms. Midrange/treble waveforms are much smaller, much more directional, and much more affected by reflections and phasing issues.

 

[SourDeez 10+ year member]

The main benefit is to increase off-axis response and/or to otherwise shape the response on midrange drivers; which is exactly what zako stated.
On a sub-woofer you would *decrease* your cooling (the dust cap is the cover of the air pump after all - without the cap air doesn't pump through the pole vent or internal gap at all) and decrease your SD by the amount of the pole. Also... you are opening an air-leak directly into your enclosure ; even more so on drivers with vented gaps (air directly from the box could come out, through the gap, and out around the phase plug). Also you would open up the gap for debris, especially in car audio, hence the term "dust cap"

lol

game over

close thread.