Talk:Electrical characteristics of dynamic loudspeakers

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Impedance graph[edit]

I was looking at the impedance plot that is shown at the top of the page... this does not look 100% textbook to me, there is a slight second hump in the resonance - it looks like the kind of thing you get with a tweeter that has a slight air leak. Also the peak looks a little lopsided. There are also a number of ripples above the resonance in a region which is normally smooth (while the diaphragm moves rigidly). I did not want to replace without explanation, I can find a suitable replacement if people think this would be helpful. It may also be useful to have a tweeter impedance graph too. Jackocleebrown (talk) 21:58, 2 June 2008 (UTC)

Aha! I've just had a look at the comments with the image, so is this an impedance plot from a thiele/small model in an enclosure of some kind? That explains the things I mentioned above. Would a real measurement not be more appropriate? —Preceding unsigned comment added by Jackocleebrown (talkcontribs) 22:00, 2 June 2008 (UTC)

Comment: impedance plots vary widely across speaker designs, and there is no universally accepted "correct" or "target" impedance response. Perhaps clarifying the purpose of any impedance graph would help clarify if the current graph is appropriate or not. — Preceding unsigned comment added by (talk) 14:32, 4 August 2012 (UTC)

Nominal and minimum impedance[edit]

The minimum in Impedance above resonance is perhaps more appropriately called Zmin. Znom actually is just a rating and is not defined by any measured response. For example, 8 ohm rated loudspeakers may have a measured minimum above resonance in the range of 5-8 ohms. I propose a change in the diagram which reflects this and also shows the impedance phase curve.--Ron E 14:28, 22 April 2006 (UTC)

The nominal impedance (Znom) of a speaker is usually less than the quoted one - the quoted one is at some frequency (probably the mid-band freq of the operating range of the speaker) and this is always higher than the nominal impedance. So a 4 Ohms (quoted) speaker will have a DC resistance of about 3.3 ohms (advertised nominal) and a nominal (measured minimum) impedance of about 3.5 to 3.9 ohms. The nominal impedance is of consideration in crossover design. For amplifier design the quoted impedance or DC resistance may be used. There is a confict of terminology here - the "nominal impedance" stated is the quoted impedance as far as selling the product goes. From a technical point of view, the Zmin is the Znom and is different from the quoted impedance. Rohitbd 08:21, 28 April 2006 (UTC)
A credible source speaker impedance says otherwise. The definition of the word nominal is "not actual". From a technical point of view, the nominal impedance (either my definition or yours) is of no consequence in crossover design; rather, the actual impedance (complex-valued, for you that means impedance phase and magnitude) is of primary importance. A 4 ohm nominal impedance (or "quoted impedance", to use your incorrect terminology) loudspeaker may have a DC resistance anywhere from ~2.5-4 ohms, and a minimum impedance in the 3-5 ohm range.Ron E 01:03, 20 May 2006 (UTC)
Loudspeaker driver manufacturers all rate their speakers' nominal impedance as per EIA-299, which is simply 1.15 times the Zmin. Having worked in the OEM automotive audio industry for 19+ years, I have measured hundreds of speaker drivers and can confirm this. I agree that from the technical standpoint of a loudspeaker system designer, the 'nominal' impedance isn't of much consequence, as the actual complex impedance curve will be used in passive crossover design for a multi-speaker loudspeaker system. The nominal rating, however, gives you a good idea of the minimum impedance characteristics of a speaker in a single, easy number. 4 ohm speakers are called 4 ohm speakers, even though Zmin may be 3.6 ohms. You don't call this a 3.6 ohm speaker, you call it a 4 ohm speaker.
While it may just seem like semantics, it aids the novice or uneducated when speakers and amplifiers are interfaced. This is important in biamp, triamp, or multi-amplified systems utilizing active crossovers, as different amplifier chips may be stable only for 4 ohm or higher speakers, while other amplifiers may be stable for 2 ohm or even 1 ohm speaker drivers. Jastratman 17:07, 23 January 2007 (UTC)