How to read speaker sensitivity rating?

Just my two cents, Mitch, but at 40k for the Dominance, shouldn't an audition trip to Utah be part of you plan? Or does Zu's generous return policy apply to the flagship as well?

John

Will someone please explain "phase angle"?

It refers to the phase relation between voltage and current, at a given frequency.

Speaker impedance, or any impedance, will be some combination of resistance, inductance, and capacitance. For a pure resistance, voltage and current are in phase with each other at all frequencies. In the case of a pure inductance, voltage leads current by 90 degrees (1/4 cycle of the signal frequency, denoted as +90 degrees). In the case of a pure capacitance, voltage lags current by 90 degrees (denoted as -90 degrees).

Pure resistances, pure inductances, and pure capacitances only exist in theory, although depending on the device, the application, and the frequency it is often reasonable to neglect two of the three terms as insignificant. That is not generally true for speakers, though.

Derivation of the net phase angle corresponding to a given combination of resistance, inductance, and capacitance, at a given frequency, involves some mathematical complexity, and is described in my post here in a thread on the difference between resistance and impedance.

Phase angles that are significantly capacitive, say -40 degrees, more or less depending on impedance magnitude, make life more difficult for the amplifier because they increase current draw. If significantly capacitive phase angles coincide with frequencies at which impedance magnitude is low, current requirements are increased further.

The speaker reviews in Stereophile generally include a plot and a discussion of impedance magnitude and phase angle, in John Atkinson's measurements which usually appear at the end of the review.

Regards,
-- Al

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Jdoris, an auditon trip to Utah is certainly under consideration. There are several speakers that I am considering. All of them require a plane ticket for me to audition them at their location. The freight to get them to me in Los Angeles will be ungodly. That's why I'm asking so many questions on this forum....to eliminate any unnecessary travel. Of course SOME travel will be required. I'd like to narrow it down to two finalists. I am also considering a set of Genesis 201 speakers, VMPS V60/VLA combo, Magnepan 201 with a separate subwoofer.
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I am certain that the specs. on the SPL ratings for the Kappa 9's are off by a long shot....CERTAINLY not 102db with 1 watt of input. I owned a pair about 25 years back, and would say they are more in the area of 83 db SPL at 1 meter and 1 watt input. I remember being in a room with some monster amps pushing them, and watching the meters on the amps jumping around between 200 and 700 watts, and the speakers were certainly not hitting levels in the room much beyond 105db or so. I also found the same specs. you mentioned on the Kappa 9's on a search on the web, and here they are:

Nominal Impedance: 4 to 6 ohm (recommends amps that can go lower)
Power Rating: 60-340 watts RMS
Efficiency: 102 dB SPL @1 watt, 1 meter
Crossover Frequencies: 80Hz, 800Hz, 4500Hz
Frequency Response: 29Hz-45kHz +/-3dB
Physical specs:
1x - SEMIT Supertweeter
1x - EMIT Tweeter
1x - 3" Edgewound Voice Coil Polydome Midrange Driver
1x - 5" Polypropylene/graphite Diaphram Polygraph
2x - 12" Cast Frame , L/C Tuned Woofers

It also shows their impedance to be 4-6 ohms, but they certainly dip WAY below that. Play a 1khz test tone through your Kappa 9's, use an amp with accurate wattage meters and give them 1 watt... Measure the SPL output from a meter away from the midrange drivers using an affordable Radio Shack SPL meter, and I bet it will read somewhere in the low 80db area. These speakers need a LOT of power to hit 102db SPL, The Zu speakers certainly do not.

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Bug,

Yes, those are the exact specs that I used, which is why this
whole thread started. I bi-amp my Kappa 9's with four 900
wpc @ 4 ohm monoblocs. I did not understand what those specs
meant, but I do know that they looked very similar to the
specs that I read on the Zu Dominance. It was mentioned that
the Zu Dominance was being driven with authority by a 20 watt
tube amp. The Kappa 9 would vaporize a 20 watt tube amp.
The Kappa 9 specs posted on the web are what I've been using
as a comparison chart when considering other speakers. So,
all I've needed to know all along was that those Kappa 9
specs posted on the web are wrong.
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