The opposite, 102 db means a sound pressure level of 102db with 1 watt of input, vs. just 78db with the same input. Not necessarily easier to drive, just plays louder with the same power. Harder to drive usually relates to the ohm rating - 4 ohm is a harder load on an amplifier than 8 ohm is.
How to read speaker sensitivity rating?
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When reading the sensitivity rating on speaker specs, does a lower number mean the speaker is easier to drive than a speaker with a higher number? Such as a speaker rated 78 db would be easier to drive than a speaker rated 102 db?
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When reading the sensitivity rating on speaker specs, does a lower number mean the speaker is easier to drive than a speaker with a higher number? Such as a speaker rated 78 db would be easier to drive than a speaker rated 102 db?
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. Okay, assuming the nominal impedance for both speakers is 4 ohms. Does that mean the one rated at 78 db will play louder than the one rated at 102 db at the same power? I've seen a few discussions here about the difficulty of some speakers to be driven and I often see sensitivity numbers thrown around. . |
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. Z-man, Not pulling your leg here. the reason that I'm asking is that I own several pairs of Infinity Kappa 9 speakers. They are notorious amp-killers. I read the specs on them and it says 102 db. Well the logic seems that if everyone knows that those things are impossible to drive, the higher number must mean harder to drive speakers. I am considering purchasing a pair of Zu Dominance speakers. The sensitivity rating is 101. I read an article about them being driven at CES by a twenty watt tube amp. Well if the sensitivity rating is only 1 db off of the rating of the Kappa 9, something doesn't add up. Viridan noted that the impedance would make a difference. The Zu speakers are 6 ohm and the Kappa 9 are 4 ohm. I've always known that the lower the nominal impedance of a speaker would make it harder to drive, I just never understood the sensitivity thing. Also, if you look at any of my previous posts, never have I had a discussion of speaker sensitivity. I'm very sincere about my lack of knowledge in this area. I posed the question here because I do not want to make a $40k error out of ignorance. The Zu Dominance speaker is a custom order and there are no dealers that stock them so that I can audition them. I'm trying to gather as much info as I can in order to make an informed decision before I commit. So, it's pretty much as I've always thought, lower impedance ratings pretty much will determine the amount of muscle that you would need to drive the speaker. In some threads around here, it seemed that sensitivity ratings were thrown around quite a bit as a big factor in the difficulty in driving a speaker. I'd like to try tube amps, and I know that the high powered tube amps cost an arm and a leg, and I only have an arm....a small arm. So it's important for me to make sure I get a speaker that will play loud with serious bass when powered by a tube amp. If you've checked the room size my system is in, you'll see that the speaker will need to be able to deliver some serious spl's. Also, I checked my history of posting here and have seen with a lot of consistency, that I've always posted a barrage of questions prior to purchasing an item. With every addition to my system, I find that I have posted lots of questions on this forum about that item. Amazingly, every time I don't post a question and I buy something, the purchase turns out to be a clunker. I'm more of a music lover than an audiophile. I've never rolled a tube in my life. I don't know how to use a soldering iron and I wouldn't dream of attempting DIY project. By being here 10 years and asking lots of questions, I've gained quite a bit of knowledge about audio. But, also every week I read something here that reminds me of how much I don't know. . |
Sensitivity, like most other specs is somewhere between misunderstood and meaningless. Without some other information, like some idea of maximum power handling and phase angles at frequency, sensitivity is just another number to hit back and forth over the net. If your 100db sensitive speaker can handle 20 watts before the smoke gets let out, that is a much different animal than the same speaker with a max power handling of 400 watts. Likewise for phase. If the speaker were a (mythical + flat) resistive load that would be a completely different kettle of fish than a similar sensitivity with a 3 to 20 ohm range and some wacky phase angle at the impedance minima. By itself? Sensitivity is not worth much as a single number. |
The Kappa 9's, when used with their "extended/normal" switch in the "extended" position (which iirc seemed to be the most commonly preferred setting), are conceivably the most difficult speaker load ever devised by mankind, at least among home speakers. In that mode they go down below 0.8 ohms at multiple bass frequencies, where lots of energy is typically required. I know of no other speaker that comes close to doing that, although I believe the Kappa 8's are not too far behind. The "normal" mode is not quite as severe, but still very challenging. I don't know what their phase angle behavior is in the bass region, but it wouldn't surprise me if it was significantly capacitive, adding to the severity of the load. I can't imagine that a Zu speaker would be anything like that. Regards, -- Al |
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FWIW, when a speaker's specs include both its sensitivity and its power handling capability, it allows the user with a similarly capable amp to estimate how loud the speaker will play safely and continuously. For example, ratings of 87dB and 150 Watts translate to a maximum volume of just over 108 dB, earth shaking but not shattering. |
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 |
. 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. . |
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. |
. 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. . |
Yes, they are certainly incorrect. I wonder if they meant to write "102db MAX SPL at rated input". You certainly would not want to torture most 20 watt tube amps trying to drive the Kappa 9's at moderate listening levels, not to mention what the distortion would do to those ribbon tweeters when the amp starts clipping! |
I don't believe this is the original manual. It shows the product history, which wouldn't make any sense for a new product. Also, the revised 6-98 date printed on it. Must of been definite errors made somewhere. The new parts still available doesn't match up correctly, whatever one may be right or wrong.[http://www.infinity-classics.de/infinity/technik/manuals/Kappa_9_technical_sheet.pdf] |
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. Hifihvn...you are right on both counts. The Harmon site has the model number correct, but the parts are for the Kappa 9.1, not the original Kappa 9. The Kappa 9 does not have an 8 inch mid-bass driver...it has a Polygraph and a Polydome drivers that do not appear on the parts sheet on the Harmon site. The Kappa 9.1 was a ported design that was much easier to drive than the original Kappa 9. The bass drivers were different also. . |
