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Old 8th February 2004, 05:09 PM   #1
kan3 is offline kan3  United States
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Default voice coil inductance VS transient response

ok, i'm sure you seen this topic before but someone please explain this to me(relating strictly to subwoofers)

i've heard two sides to the story:

adire audio states here LINK that inductance in a subwoofer DOES have an adverse effect and SHOULD be a spec that matters in driver selection....what values are considered high and low..doesn't go into any kind of detail

now linkwitz, on his site, states that voice coil inductance has little real world effect on sub bass performance

someone want to help me out here?
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Old 8th February 2004, 05:51 PM   #2
sreten is offline sreten  United Kingdom
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I'm with Linkwitz on this one, at subwoofer frequencies
inductance is an issue that can be ignored, and it has
no influence on the transient response of the sub,
given the effect of the normal subwoofer filtering.

Adire Audios article stupidly ignores the effect of any
filtering applied, besides that its so wrong in its mis-
application of simplistic physics I don't know where
to start to correct it, best just to safely ignore it.


sreten.
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Old 8th February 2004, 06:15 PM   #3
Svante is offline Svante  Sweden
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Default Re: voice coil inductance VS transient response

Quote:
Originally posted by kan3
ok, i'm sure you seen this topic before but someone please explain this to me(relating strictly to subwoofers)

i've heard two sides to the story:

adire audio states here LINK that inductance in a subwoofer DOES have an adverse effect and SHOULD be a spec that matters in driver selection....what values are considered high and low..doesn't go into any kind of detail

now linkwitz, on his site, states that voice coil inductance has little real world effect on sub bass performance

someone want to help me out here?

Sure, voice coil inductance affects the transient response, in the technical sense. So does the crossover filter, to a much higher extent. It is not important. What the woofer does not produce in terms of sharp onsets, will appear in the midrange and/or tweeter.
The importance of transient response is IMO greatly exagerated. The relation what the technician calls good transient response when he/she looks at the waveform and what the listener perceives as "quick response" is far from 1-to-1. I am not saying that different speakers can be perceived as having different responsiveness, I just don't think the transient response (as the technician sees it) is the explanation.
Focus on frequency response instead, that is far more important.
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Old 8th February 2004, 06:58 PM   #4
SY is offline SY  United States
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Quote:
I just don't think the transient response (as the technician sees it) is the explanation. Focus on frequency response instead, that is far more important.
They're one and the same, bolstered by a couple of centuries of transform use. I think the analysis at the link is largely doo-doo, but rather than get bogged down in theorizing, it's easy to test the assertion- take one of those high inductance woofers (their definition of "high inductance" is unstated) and measure the near-field frequency response when excited by a normal low source Z amplifier. Oh, it looks like it's not rolling off below 1kHz? My, my, whaddaya know!
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Old 8th February 2004, 07:06 PM   #5
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... and just when you think that you've heard it all ...
subwoofer transient response?
I agree with Svante and SY.
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Old 9th February 2004, 09:41 AM   #6
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woofer speed

LOL the old wives tale returns


its Box resonances
resonance over ring
room resonances
peaking ports , etc
that do the yuck sound! Focus on the majors

The ONLY Thing i can think of to do with high LE is that some one stated that you get IMD if operating the woofer near its roll off-but who runs their subs full range ?

jbl runs their 15"s up to 1khz but they have low le anyway..
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Old 9th February 2004, 03:08 PM   #7
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Hi all, perhaps a bit of clarification...

Many times, people bring up the old myth about the "acceleration factor", BL/Mms, as proof of why one driver has better transients than another. In fact, this factor is nothing but efficiency, which has ZERO relationship to transient response. This is why the paper was done in terms of acceleration and how accleration is SPL, not transient response (rather, the rate of change of acceleration is transient response).

As far as subwoofers go, many of the higher excursion subs out there have inductances in the 5-6 mH range. With a 3 Ohm DCR, this puts the inductive roll-off around 100 Hz. Sure enough, the inductance of these drivers definitely affects the transient response, even with a crossover at 100-150 Hz (in essence, you have another order of crossover).

Anyway, of course the crossover can have a major impact on the transient response of the system; that is not challenged at all. if the crossover is within the pistonic passband, then it is the main limiter of frequency extension (transient response). However, when talking about the raw driver itself, it's not mass or BL that is the limiting factor (and hence not that BL/Mms thing) - it's strictly the inductance that sets your bandwidth/transient response limitations.

Please understand the paper is written for your average car audio person, who probably never stopped to think that a voice coil is essentially a high DCR inductor! Thus the simplistic terms and method to explain why it's inductance that matters, not mass or BL or any other factor.

Dan Wiggins
Adire Audio
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Old 9th February 2004, 05:01 PM   #8
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The Peerless CSX 10" has an Le of 2.9mH.
The Peerless XLS 12, (5 ohm version) has an Le of 4.2mH.

The Adire Shiva Mark IV has an Le of 2.12mH-much less.

Both Peerless drivers have an aluminum shorting ring.

The Adire Shiva does not.

Does this affect transient response?

PS: The Peerless CSX 10" has a smooth frequency response to above 1.5 KHz.

PPS: How much does this difference make, if any, if you are going to cross over between 100 Hz and 200 Hz in a typical subwoofer application?
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Old 9th February 2004, 05:57 PM   #9
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Keltic,

A shorting ring can affect nonlinear inductance based distortion (typically even order components from Le varying as the driver moves forward and backward). If it lowers inductance, it will inherently affect transient response.

For a typical subwoofer with these specific drivers, it really doesn't matter. However, for some subs - and for some midbass applications - it does matter.

Again, the idea was to bust the myth of "BL/Mms = transient response".

Dan Wiggins
Adire Audio
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Old 9th February 2004, 07:15 PM   #10
Wizard of Kelts
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Quote:
Originally posted by DanWiggins
Keltic,

If it [shorting ring] lowers inductance, it will inherently affect transient response.

Dan Wiggins
Adire Audio
Okay, but if the shorting ring does lower Le, will that show up on the Le spec?

In other words, for crossover purposes, is a sub with a spec of 2.9mH and a shorting ring equivalent to a sub with a spec of 2.9 mH without a shorting ring? Or will the shorting ring cause the sub to somehow act like it has less inductance than is listed, in reference to crossing the sub over at 100 to 200 Hz?

I realize these are not your woofers with the shorting ring, so you are not really responsible for answering that question.
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