I've never really understood what is meant by the 'critical range', it's one of those terms thrown about a lot, but it seems to movable to fit whatever the author wants it to be, is there a definition on where it starts and ends?Going back to the "critical range" its actually does extend a bit higher in frequency than many think. most sensitive in the 2 - 5kHz range.
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TEST: ATC SM75-150 mid-dome
- Thread starter watchnerd
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This goes back to about 1980 I think. They have used ATC drivers in several of their top models. I think this one is the Response 5
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Didn’t PMC also use ATC drivers at some point?
Keith
Keith
I think so, I think they use the Volt version now though.
https://www.wilmslowaudio.co.uk/volt---vm527-vm752-and-vm753-39-c.asp
Wasn’t there some accusations of spec stealing and then asking volt to manufacture?
Keith
Keith
It simply describes the frequency range where your hearing is most sensitive. Shown in the Fletcher munson graphs. Note how your hearing changes with volume level.
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It’s the range
The most obvious definition is that it’s the range in which we (on average) can hear sounds lower in level than “0dB”. But as you say it’s often used pretty loosely..
The most obvious definition is that it’s the range in which we (on average) can hear sounds lower in level than “0dB”. But as you say it’s often used pretty loosely..
So based on the graph above about 800 - 6k?
If so that covers the mid to tweeter crossover point on every pair of cone and dome speakers ever made, despite endless reviews where the crossover was described as avoiding the critical range.
Which is why I made the choices I did with my own design. The mid currently covers 700hz to 4.6kHz, I am going to try tweaking 600Hz to 5kHz just out of curiosity.
restorer-john
Grand Contributor
There's a reason Wow and Flutter is tested at 3/3.15KHz. It's the part of our hearing range where we are most sensitive to pitch/timing variations. Amir could no doubt talk at length on this subject?
That makes perfect sense to me, the crossover thing not so much.
Interesting, dynaudio might be ahead of you...
https://www.dynaudio.com/professional-audio/lyd/lyd-48
AnalogSteph
Major Contributor
Holy crap, a 5.5 kHz tweeter crossover. That's ridiculously high even given the relatively low midrange-tweeter distance. Vertical dispersion is not likely to look particularly pretty in that range.
Yep, just like I suspected - dispersion plots are in the spec sheet, and in fact they look very disappointing for a modern speaker all around. This would be appropriate for something designed 30 years ago, not in 2017. Not even close to the likes of Genelec, Sennheiser (K+H) or JBL, or even a number of modern-day home hi-fi speakers, including advanced DIY designs.
As far as the "critical range" goes, this is generally considered to be the vocal range up to 3 kHz or so. People were generally reluctant to put their crossover frequency in there as it would yield angle-dependent tonality changes due to the kind of irregularities you can see in the LYD48. These days you can put the tweeter in a waveguide and cross it over deep (and actively / digitally at high order to boot), which helps a ton with these things.
Speaking of driver measurements, the world could use a lot more data points on the effect of current driving on nonlinear distortion, Esa Meriläinen style. (The paper was available somewhere, can't find it right now. He measured 2-tone intermod at nominal 1 W levels.) It is hard to guess how a large midrange dome like this would fare, the effect on a 1" dome tweeter was quite small. The speakers that seemed to benefit most were cones with voice coils wound on non-conductive formers, and it should be obvious that you would be well-advised to stay far away from resonance (or use an amplifier that transitions to voltage drive down there) - down there you're generally excursion-limited anyway, and those nonlinearities remain unchanged. Interestingly, by the time the speaker crossover includes substantial series resistance, that's moving towards current drive, too - so basically your average tweeter in a passive XO is already operated like that.
Here's a tip - if your measurement mic is as noisy and exhibits as much 2nd harmonic as mine does, try a regular large or small diaphragm condenser with a (largely) flat response and decently low noise instead. Yes, it has to be pointed more accurately and minimum distance will be a concern due to proximity effect if it's a regular cardioid, but chances are it'll do much better at picking up the harmonics due to lower noise floor. I've had rather good results with a lowly t.bone SC-400, a house brand 50€ fixed cardioid China LDC... guess I should be looking for its cardioid/omni bigger brother, the SC-600, which did quite well in a review. Not sure which other mics are using the same capsules (they look like readily available 32mm Chinese LDC jobs), the electronics are rather common (those with an internal low-cut switch, flat response with no special EQ apparently).
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Around the crossover point, the output from the two drivers sums correctly in the vertical plane only at one point in space (usually on axis with the tweeter).
As the mic/listener moves vertically off axis, the relative distances of the tweeter and midrange change, causing the sound waves to sum at some frequencies and cancel at others.
This causes dips/nulls in the frequency response at these off-axis positions.
The severity of these nulls increases when the crossover is at a higher frequency (due to shorter wavelengths) and when the distance between the drivers is greater (resulting in greater differences in distance between the drivers at a given measurement/listening position).
For a more detailed explanation you can google “loudspeaker lobing”.
The sonic effects of lobing are debatable, but the most obvious effects of more severe lobing would be a narrower vertical sweet spot and early reflections not cohering well with the direct sound.
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