Hi,
Having read all of the interesting Synergy threads around here and being a dipole addict myself, I could not help thinking about how a combination of the two could look like - and ended up with the sketch attached (sorry for my awful drawing skills - and no, that is NOT Mickey Mouse
)
That's basically:
- a Synergy horn - actually more of a waveguide - without the back enclosure
- additionally, the throat would be slotted to allow air flow and hopefully a null in the radiation pattern at the back. The HF unit would be a planar (Neo3).
- the horn / waveguide profile could be only horizontal (the sketch showing its section from above). But not necessarily.
_IF_ that worked as I envision it, one could _hopefully_ have:
1. the advantages of a Synergy horn in terms of coherent radiation of the drivers
2. a cardioid-like response pattern
3. controlled directivity (a combination from both dipole effects as well as from the horn itself)
Of course, I'm not talking about big bass here, but aiming for something like above 150-200Hz.
At the moment, I would not know how to simulate such a beast. I'd be very interested in your opinions.
Best regards,
Liviu
Having read all of the interesting Synergy threads around here and being a dipole addict myself, I could not help thinking about how a combination of the two could look like - and ended up with the sketch attached (sorry for my awful drawing skills - and no, that is NOT Mickey Mouse
)That's basically:
- a Synergy horn - actually more of a waveguide - without the back enclosure
- additionally, the throat would be slotted to allow air flow and hopefully a null in the radiation pattern at the back. The HF unit would be a planar (Neo3).
- the horn / waveguide profile could be only horizontal (the sketch showing its section from above). But not necessarily.
_IF_ that worked as I envision it, one could _hopefully_ have:
1. the advantages of a Synergy horn in terms of coherent radiation of the drivers
2. a cardioid-like response pattern
3. controlled directivity (a combination from both dipole effects as well as from the horn itself)
Of course, I'm not talking about big bass here, but aiming for something like above 150-200Hz.
At the moment, I would not know how to simulate such a beast. I'd be very interested in your opinions.
Best regards,
Liviu
Attachments
Liviu,
1) The virtual single point source coherent radiation of the Synergy design would be eliminated with open back drivers.
2) The response would not be cardioid over any useful frequency range.
3)The Synergy directivity is controlled by the horn sidewall angles, adding rear radiation from the drivers would loose both pattern control and low frequency response, none of the drivers would be properly loaded.
Your concept would not share any of the Synergy design goals, and would be a bad (as in no-good) dipole as well.
Other than that...
Art
Thanks for your thoughts.
Strictly speaking, yes. But at least wrt. forward radiation the drivers should still be coherent - after all the coherence is achieved by having the right time aligment in the horn plus lots of overlapping.With the dipole peak at something like 400 Hz, backradiation should not interfere too much in the forward response.
As to the back radiation, that would be, of course, non-coherent, and probably imbalanced, requiring additional measures.
A perfect cardioid is out of scope (actually, below the dipole peaks of the 2 sides, it would be a 3-lobe Mickey Mouse, not cardioid). However, what I want is:
- to have a frontal lobe with close to perfect directivity. A typical dipole with a constant width will bloom above some hundreds Hz - this can be countered by the horn effect (or using a 4-way progressively narrower baffle as in NaoNote and Linkwitz approach).
- to have a null at the back. That might indeed be tough to get above the dipole peaks and the tweeter radiation needs to be absorbed at the back (which is not that difficult)
As mentioned in the first post, this is not meant to reproduce low frequencies (and yes, this differs from the Synergy design goals).
The rear radiation of the drivers _is_ a form of controlling directivity (below dipole peak), why should this lose pattern control ? I don't see why one cannot combine 2 techniques: dipole at lower freqs + horn at higher freqs. I do admit that it will not be a trivial task to get them work together.
It partly shares some: coherent radiation of the drivers and controlled directivity of the forward radiation.
Since it will not be a dipole at all, but a multi-pole, I agree
However, I don't remember having seen any proof that the back radiation of the speaker needs to be coherent or have a perfect directivity as well - except you have really strong direct reflections. Yes, it has to be balanced in terms of the overall power response , but other than that ?
Strictly speaking, yes. But at least wrt. forward radiation the drivers should still be coherent - after all the coherence is achieved by having the right time aligment in the horn plus lots of overlapping.With the dipole peak at something like 400 Hz, backradiation should not interfere too much in the forward response.
As to the back radiation, that would be, of course, non-coherent, and probably imbalanced, requiring additional measures.
A perfect cardioid is out of scope (actually, below the dipole peaks of the 2 sides, it would be a 3-lobe Mickey Mouse, not cardioid). However, what I want is:
- to have a frontal lobe with close to perfect directivity. A typical dipole with a constant width will bloom above some hundreds Hz - this can be countered by the horn effect (or using a 4-way progressively narrower baffle as in NaoNote and Linkwitz approach).
- to have a null at the back. That might indeed be tough to get above the dipole peaks and the tweeter radiation needs to be absorbed at the back (which is not that difficult)
As mentioned in the first post, this is not meant to reproduce low frequencies (and yes, this differs from the Synergy design goals).
The rear radiation of the drivers _is_ a form of controlling directivity (below dipole peak), why should this lose pattern control ? I don't see why one cannot combine 2 techniques: dipole at lower freqs + horn at higher freqs. I do admit that it will not be a trivial task to get them work together.
It partly shares some: coherent radiation of the drivers and controlled directivity of the forward radiation.
Since it will not be a dipole at all, but a multi-pole, I agree
However, I don't remember having seen any proof that the back radiation of the speaker needs to be coherent or have a perfect directivity as well - except you have really strong direct reflections. Yes, it has to be balanced in terms of the overall power response , but other than that ?
It would probably be easier to use just one horn and an additional driver radiating to the back in order to achieve cardioid behavior.
One important issue: One won't be able to maintain cardioid or dipole behavior once the speaker is put in a room.
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Please explain how you define "behavior" in this case. Doesn't each and every loudspeaker change its "behavior" when put in a room?
Rudolf
Correct. I was talking about the low end. Does it make sense to put effort in creating a dipole or cardioid when the result is swamped by the room anyway?
It is a question of definition:
If someone draws a perfect figure 8 pattern somewhere, he should be aware that this will apply only in a short part of the dipole frequency range (the ramp up to the first dipole peak).
If we define a dipole as two sources of opposite phase separated by a defined distance, then a DBA is a (sort of) dipole too. And every multiple sub solution would behave like a dipole for a certain frequency at a certain point in the room.
Even if we let the room swamp everything: The perfect dipole would be the system that nets to constantly zero room pressure at all times and all frequencies.
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