I am sitting here listening to my system, hitachi tt, realistic phono pre, shuguang i12 tube int amp and B&W DM302's.
Sounds great, Tubular Bells, and im thinking, there might be a reason for most people to be happy with the mediocre one way bookshelf/htib speakers.
I read that we are not frequency based listeners really, we are time based, and frequency is a derivative of time.
Phase errors, time errors, can mean the difference between being lunch or eating lunch.
in a one driver system there are no phase errors as in a two or three way system.
so while a three way speaker can play more quantity of sound, 30-20,000hz, a one way system has better quality, no timing errors.
Fundamentally a phase error will trigger the fight or flight response weve spent thousands of years honing. A small error will be causing us to perk up our ears "something not quite right here" and this constant triggering of this is what leads to listener fatigue.
A fullrange system OTOH has no phase errors and where it falls down, the freq. extremes are not a cause for alarm in our brain so we can relax while we listen.
Question is can i accept this tradeoff? Can you?
Think im gonna find some cheapass 5 1/4" fullrangers to compare with my DM302's and report back.
Sounds great, Tubular Bells, and im thinking, there might be a reason for most people to be happy with the mediocre one way bookshelf/htib speakers.
I read that we are not frequency based listeners really, we are time based, and frequency is a derivative of time.
Phase errors, time errors, can mean the difference between being lunch or eating lunch.
in a one driver system there are no phase errors as in a two or three way system.
so while a three way speaker can play more quantity of sound, 30-20,000hz, a one way system has better quality, no timing errors.
Fundamentally a phase error will trigger the fight or flight response weve spent thousands of years honing. A small error will be causing us to perk up our ears "something not quite right here" and this constant triggering of this is what leads to listener fatigue.
A fullrange system OTOH has no phase errors and where it falls down, the freq. extremes are not a cause for alarm in our brain so we can relax while we listen.
Question is can i accept this tradeoff? Can you?
Think im gonna find some cheapass 5 1/4" fullrangers to compare with my DM302's and report back.
It's a nice idea, but don't kid yourself that wideband units are free from phase related issues. Just taking the most obvious example, a unit with a parasitic / whizzer cone is essentially a type of 2-way, albeit with a mechanical rather than electrical XO. And so on.
Granted, all other things being equal, drive units with as wide a linear response BW as possible is the ideal, since if XOs are required, you can push them out of our critical hearing BW to somewhere they're less likely to cause audible problems.
Granted, all other things being equal, drive units with as wide a linear response BW as possible is the ideal, since if XOs are required, you can push them out of our critical hearing BW to somewhere they're less likely to cause audible problems.
The research would say frequency response and extention far out way phase coherence (at least from what I've read). But I have been debating how downplayed phase is in the research out there. Good timing. I just was asking someone about this. I hope to steal there wisdom soon when I can visit. I'll wait to vote once I've had a chance to experiment.
All in phase, of course. Reflections from floor and ceiling will go in phase as well. Endless nearfield, tiny displacements of cones even when bass is equalized below Fs, extremely low distortions. No sweet spot. Accurate imaging.
Nirvana.
I would add the 3'rd choice: "Both". Can't vote now.
If you plot air pressure or velocity against sound or watch it on a scope you see the same thing...high frequencies riding on the lows...so if your driver does the same thing accurately there's no "doppler shift" involved. As long as the speed of the highs and lows propagates the same, no problem. When people talk about doppler and "freuqency riding" as a problem it's usually in reference to a more complex situation like the old coaxial KEFs where the shape of a moving woofer cone was used as the horn for a tweeter...the effect of the "horn" (woofer cone) itself moving could be distorting the treble.
Bit of a sweet spot for phase and perfect soundstage image, but an in-phase line array definitely makes for better stereo balance and coverage everywhere; wonderful for large rooms IMHO. Up close, you tend to hear mostly the drivers (or line section) directly in line with your ear, and the off-center sources above and below don't create a comb-filter effect if they are a near-continuous line source and the ends terminate with ceiling or floor reflections to sound as if the lines were infinite-length. But as you get farther back, the sound intensity from the cylindrical wavefronts decreases linearly with the distance (intensity spread only horizontally), whereas the normal spherical wavefronts of a point source decrease with the square of the distance (spreading vertically and horizontally in 2 dimensions). So line sources sound "quieter" close-up and "louder" farther away, compared to point sources. Sometimes less impressive, but much easier to live with. Of course, carefully controlling dispersion can have even more effect on the farfield ...thus the ongoing debate in pro PA circles.
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Hi Cyclecamper
I was thinking some more about this today. Not sure if I understand the similarity with what appears on a scope trace of a microphone output. The way I'm thinking about it is imagining a mid-range driver or tweeter bolted to the wall vs. the same driver being whizzed backwards and forwards in an arbitrary pattern. The way I see it, the full range cone is behaving in just that manner as soon as the bass kicks in. It doesn't duplicate what a microphone would record, because the microphone diaphragm hardly moves at all, and I don't think the effect is constant regardless of scale.
Right;
that's why line arrays with tiny displacements of membranes sound so naturally. I recently bought 32 of cheap microphones to experiment with line arrays with very small and light membranes, let's check how well they will perform. Need to order some baffles with holes drilled, though...
(Do you mean 32 cheap speakers?)
I love the idea. Is this a more practical alternative to the electrostatic?
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Not true.
The point about doppler shift is that when the same driver produces low frequencies with significant excursion at the same time as high frequencies, the high frequencies are phase/frequency modulated by the excursion.
This does NOT happen when the source of low and high frequencies are different drivers, or indeed different instruments or sound sources in the natural world.
The fact that high frequencies appear to "ride on" low frequencies when measuring the electrical waveform on a 'scope is irrelevant - they are simply summing together at the listening point, and will do so even when the two frequencies come from different drivers or sound sources.
In the case of doppler distortion from a signal driver, the presence of the low frequency tone will actually alter the high frequency tone, hence doppler distortion. Almost impossible to see on a time domain display like a 'scope, but easy to measure on a spectrum analyser.
That too is a type of modulation distortion where low frequency cone excursion is modulating high frequencies.
It can happen even in non-coaxial wide range drivers. One example is full range drivers with radiating (aluminium) dust caps - there is a cavity resonance under the dust cap which if untreated (damping, vented pole piece etc) can cause a series of peaks and dips in the treble response. When the cone moves with bass the size of the cavity behind the dust cap changes and the frequency of the peaks and dips moves up and down with excursion.
(Possibly the effect that people are actually hearing when they think they are hearing frequency modulation distortion on full range drivers...and one thing in favour of phase plugs over dust caps for full range drivers)
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Unlike a woofer, a microphone has no significant low frequency diaphragm excursion relative to the high frequencies wavelengths even when it is recording quite high SPL levels of low frequencies, so a microphone introduces (almost) no dopper distortion.
Easily proved experimentally by measuring two separate sources of low frequencies and high frequencies and looking for IM products with a spectrum analyser. If there was doppler distortion it would show up as sidebands on the high frequency tone.
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Not true. The cone does not produce high frequencies independently from magnet. The coil in respect to magnet field does that. No doppler shift since the magnet does not move.
Uhhh....
Nice try, but there are several major problems with your claim.
1) What you suggest would only apply to an overhung voice coil design, where the "active" part of the coil where the motive force is coming from (the portion within the gap) effectively stays the same distance from the listener with cone movement.
It would not apply to underhung designs where the entire voice coil length is always "active" and moves back and forth within a longer gap. If your theory was correct overhung voice coil designs would have no doppler distortion but underhung designs would.
Empirical measurements do not show this, nor have I ever seen any literature to suggest that there is any significant difference in doppler distortion between underhung and overhung voice coil designs.
2) The distance from magnet gap to listener staying the same is irrelevant because we have three different propagation speeds in the total path length - the propagation speed of the impulse from the voice coil to the voice coil former/cone junction, the propagation speed through the cone itself, and finally the propagation speed through air, and they are all very different.
The slowest and most important is the air path propagation speed occurring from the cone to the listener. Propagation speed of bending waves through a paper cone above cone breakup is roughly 2x faster than through air, hence the approximate 30 degree cone angle of many wide range drivers to ensure coherent wave arrival at the listener.
At frequencies below cone breakup there is essentially no propagation delay, as the cone is moving as a solid piston.
Then there is the propagation delay through the length of the voice coil former - again at low frequencies the voice coil former acts like a solid tube with no delay, at high frequencies there is a very small delay from the compression wave travelling through it but this is many times faster than the propagation speed of sound through air, and also a lot faster than bending wave propagation through a cone.
End result - at frequencies below cone/voice coil former "breakup" (two different frequencies) there is no significant additional delay between the voice coil and the junction of the cone / voice coil former, so the acoustic centre of the driver is very close to this junction and moves with the cone, therefore doppler distortion occurs.
Even above cone/vc former breakup frequencies the propagation delays are still very much smaller than the speed through air, so the effective acoustic centre still moves, just fractionally less.
3) Empirical measurements show that doppler distortion does exist and is easy to measure. All the literature says that doppler distortion of drivers exists, it can be calculated and measured, for example check the article on Linkwitz lab for some calculations and measurements of doppler distortion of actual drivers.
Your claim that drivers don't produce doppler distortion flies in the face of actual measurements and a mountain of literature on the subject.
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