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[email protected] dpierce.cartchunk.org@gmail.com is offline
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Default Introducing a New Horse to the Stable

On Wednesday, October 16, 2019 at 6:50:03 AM UTC-4, Mat Nieuwenhoven wrote:
On 14 Oct 2019 18:58:55 GMT, Trevor Wilson wrote:

On 14/10/2019 8:00 am, Mat Nieuwenhoven wrote:

Even a tweeter has already 15-20 microHenry of inductance.


**Not so. I haven't measured one in quite some time, but the EMIT HF
drivers, used in many Infinity speakers exhibit far lower inductance
figures than that. If I had to guess, I'd estimate the inductance figure
to be around 5 X 10^-6H. I'll see if I can locate one to measure. Then,
of course, is the sadly deleted Audax HD-3P Piezo HF driver. And any
number of ELS HF drivers.


Some data from the German magazine "Hobby Hifi", from various
manufacturers:

Omnes Audio AMT50 (Air Motion Transformer): 10 uH/20 kHz
Audaphon APR 1.0, band tweeter: 54 uH/20 kHz
Monacor DT-352NF, dome tweeter: 45 uH/20 kHz
SB Acoustics TW29B, dome tweeter: 18 uH/20 kHz
Scan Speak D3404-552000, elliptical dome tweeter: 18 uH/20 kHz
Tang Band 25-2234SD, inverse dome tweeter: 24 uH/20 kHz

Multiple have a copper covering in the magnetgap to reduce the
increase of impedance at the higher frequencies, and to reduce
distortion.


Mat's data is far closer to prevailing reality here. Trevor cites but
two potential examples: one of which never had wide distribution
and is essentially unobtainable, the other is a proprietary unit
that is, at very best, rarely found in even restricted distribution.

And even looking at the real data on the Audax, it exhibits significant
inductive behavior over its bandwidth. From 5 kHz to 7 kHz, the impedance
has a significant inductive component, then again from about 12 kHz to
almost 16 kHz, it's impedance has an inductive component to it.

The point being is that the vast majority of tweeters and speaker
systems, that is, those that are now and have been available to any
segment of consumer or pro audio market you care to choose, have
impedances in the HF region that exhibit a predominantly inductive
component. One can cherry pick counterexamples, to be sure, but
do note, that particular cherry tree is nearly devoid of usable
fruit.

Like the prior discussion on impedance in this thread, yes, there
can be found isolated examples of speakers whose arguably pathological
properties can be found to conform to a particular narrow view. But
the reality and the practicality of the actual situational use in
situ is often very different than the conclusions that might be drawn
from such a viewpoint.