Bingo.
Per the OP ...."the stickers at speaker terminals are labeled 8 Ohms nominal"
@presscot.... did the manufacturer ever say anywhere that the drivers are 8 Ohm nominal?
Amplifier manufacturers often play safe when stating what impedance their amplifiers can work into safely.
For example, my Denon amp states the speaker load should be 6 to 8 ohm.
To comply with the amplifier ratings, speaker manufacturers may give the misleading information that their speakers are 8 ohm nominal, even though the impedance of the individual drivers in today's speakers is usually 4 ohm (sometimes 6 ohm).
For example, my Denon amp states the speaker load should be 6 to 8 ohm.
To comply with the amplifier ratings, speaker manufacturers may give the misleading information that their speakers are 8 ohm nominal, even though the impedance of the individual drivers in today's speakers is usually 4 ohm (sometimes 6 ohm).
I don't have to see that specific xover schematic. I have seen them all. In 3-way loudspeaker, midrange and tweeter high-pass filters have capacitor in series with mid (or tweeter) that blocks DC current. What is left to pass DC current is: inductor from the low-pass woofer filter and the woofer itself.
It's what @Galu says, agrees this loudspeaker engineer and sometime marketing *****. Receivers don't rate at 4Ω due to European heat tests or something, so nobody wants to say their speakers are 4Ω because then people won't buy them. Plus, the coil resistance is in the denominator of the loudspeaker midband efficiency equation derived by Richard Small of Thiele-Small fame...so lower coil resistance tends to make the speaker play louder at a given volume setting and louder per watt (it's not quite as simple as that but it's a pretty dominant factor). My rule of thumb back in the day was 6.4Ω DC and up was 8Ω. Maybe 5Ω in a pinch. Less than that, it's just not 8 ohms, sorry try again liars.
Don't see how it can go anywhere, until we learn what speaker we are dealing with......
You'll have seen loudspeakers that are described as "8 ohm compatible".
Now that's a goodie! 😀
It is not assumption - every 3-way crossover must have high-pass filter for the midrange and the tweeter. High-pass filter must contain capacitor - that blocks DC current. So, your assumption that Rdc measurement (with DVM) of the whole loudspeaker (including crossover) will uncover something more than Rdc value of the woofer (plus Rdc of the woofer filter inductor) - is plain wrong.
Whether the crossover is of serial or parallel topology - it doesn't matter.
Midranges and tweeters usually have higher sensitivity than woofers, so for their attenuation resistors are used (in series with them). There is no resistor (as a component) in series with woofer, but intrinsic resistance of the inductor (which is used as a low-pass filter for the woofer) will be read by DVM as an additional resistance on top of Rdc of the woofer.
What we know so far is the Rdc of the drivers, so we can be sure: it is not 8-ohm (nominal) 3-way loudspeaker.
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I have seen 2way with no cap for tweeter, just resistor, just saying...
Still waiting for presscot to make a jig and measure impedance sweep with signal generator (stand alone or rew) according to allenB. Need to see plot with Fs and Qts, Qms, Qes and Le calculated. For each driver and complete speaker with crossover. Ready to wire $100.
Still waiting for presscot to make a jig and measure impedance sweep with signal generator (stand alone or rew) according to allenB. Need to see plot with Fs and Qts, Qms, Qes and Le calculated. For each driver and complete speaker with crossover. Ready to wire $100.
I remember the infamous RL filter "novelty" in 2-way serial topology crossover (Sonus Faber Extrema), with dubious snake-oil marketing claims.
Troels Gravesen used RL high-pass tweeter filter for a regular parallel 3-way crossover for Elipticor-3. Still, I don't buy it...
Regular serial 2-way LC crossover may have better performance than parallel in some circumstances, actually.
Troels Gravesen used RL high-pass tweeter filter for a regular parallel 3-way crossover for Elipticor-3. Still, I don't buy it...
Regular serial 2-way LC crossover may have better performance than parallel in some circumstances, actually.
Well, it seems there were requests for the information of the speakers. Let me provide it here.
Speaker terminal:
Brochure:
crossover schematic:
Speaker terminal:
Brochure:
crossover schematic:
Well, I see that resistors before mid and tweeter will make most of the fr range impedance higher...
We already established that dc resistance measured by presscot with dc multimeter is just artificialy low number due to voice coil inductance...
Adding resistance of the inductor to woofer...
So much fuzz about nothing. If one would use correct method to measure impedance there would be no issue in first place.
We already established that dc resistance measured by presscot with dc multimeter is just artificialy low number due to voice coil inductance...
Adding resistance of the inductor to woofer...
So much fuzz about nothing. If one would use correct method to measure impedance there would be no issue in first place.
When you wrote "the stickers at speaker terminals are labeled 8 Ohms" in the OP, I thought you were writing about the individual driver's stickers when I replied.
Then yesterday Mark100 asked the question: did the manufacturer ever say anywhere that the drivers are 8 Ohm nominal?
You replied:"Yes, in the brochure."
The brochure says the L990, not the drivers are a nominal 8 ohms.
Exactly..
Two words that are often confused: "speaker" and "driver".
The word "speaker" should be used when referring to the "system", and "driver" when referring to an individual transducer.
To give him his due, Presscot did make this distinction quite clear in his introductory post:
It's after that when things must have gone pear shaped! 😊
The word "speaker" should be used when referring to the "system", and "driver" when referring to an individual transducer.
To give him his due, Presscot did make this distinction quite clear in his introductory post:
It's after that when things must have gone pear shaped! 😊