The Advantages of Floor Coupled Up-Firing Speakers

[LineArray]

Concerning speaker room interaction i regard
distributed mode loudspeakers highly interesting.

The following paper is in german language unfortunately,
but on page 14 ff there are some diagrams which show
the influence of reflection in comparison to conventional
speakers.

http://www.wvier.de/texte/NXT_Tonmeistertagung.pdf

As i am experimenting with that technology, a can underline
from personal experience, that DML behave extraordinarily
benign concerning deficient acoustics in small rooms.

As the common living room cannot be modified into a perfect
listening room, a more benign speaker techology is the key
point in my view.

Kind Regards

[graaf]

Originally Posted by LineArray

Concerning speaker room interaction i regard
distributed mode loudspeakers highly interesting.

in fact DMLs are similar to cone-driver-based omni speakers in one feature that is crucial from the the perspective of room-speaker interface - they have very broad dispersion and thus maximum interaction with the room

[LineArray]

Here are some polar plots and of axis measurements.

http://www.soundcontrol.tudelft.nl/P...RB_AES2000.pdf

I cannot agree in so far, as DML directivity can be shaped by
the housing similar as with conventional speakers too.

The well known monopole-kardioid-dipol shaping of the
dispersion is possible similar as with conventional speakers.

But the CHANGE in directivity due to driver dimensions related
to wavelength does not occur as pronounced.

Have you seen the plots in the first paper ?

The diffuse radiation especially towards larger off axis angles
minimizes comb filtering to an extent, which cannot be achieved
with a piston acting speaker.

When listening to DML, the speaker "disappears" and cannot
be localized as sharp like conventional speakers.

For a conventional speaker it takes many conditions to be met
before disappearing itself: Listening room, recording everything has to
fit before music is released from the speakers.

Using a DML this is more something like the "normal mode of operation".


Kind Regards

[Key]

Whether reflections are audible or not is a function of timing and intensity. The earlier the reflection the more intense it has to be to be heard, the further on after the initial event and it can be lower in db and still distinguished.

I've found this to be true within the envelope that people seem to agree matters the most 1ms-6ms. It's a bit tricky though because above or below that envelope it seems to change. And really the whole thing is kind of counter intuitive to me. I would have thought that the earlier reflections would need to be softer to be innocuous. But you can really push a reflection way up in volume around the 1-2ms region compared to the 5-7ms region. The later the reflection in that envelope it seems the softer it will need to be to blend in with the direct sound. But if you make the reflection really short it doesn't seem like an echo but just sort of a 3-D effect that is hard to even notice unless you can turn it off.

[markus76]

Well, Blauert wrote about that some 40 years ago...

Jens Blauert "Spatial Hearing"

[graaf]

Originally Posted by LineArray

For a conventional speaker it takes many conditions to be met
before disappearing itself: Listening room, recording everything has to
fit before music is released from the speakers.

it is not that difficult, all unorthodox setups described in this thread - CFS, SLS and Carlsson - excel at disapearing act

as to DMLs I am no expert, I rely on what I have found:
http://dspace.upv.es/xmlui/bitstream...D0D?sequence=6

2.2. Distributed Mode Loudspeakers
2.2.2 Radiation Properties
(...)
The polar response of a DML is again dependent on whether it is radiating below or above the coincide frequency, as stated in several studies
Below coincidence frequency
The polar pattern is an interference pattern for an odd and even mode strip radiator, which is orthogonal and thus the radiation pattern will swap from one to another. When many modes are excited, this summation of patterns gives a quasi-omnidirectional response but in reality, strong frequency variations are occurring at the listening point.
(...)
Above coincidence frequency
For this frequency band, the sound radiation is highly directive due to the occurring coincidence. The pattern is a combination of single lobes from forward and backward waves for each excited mode. As frequency increases, such lobes become narrower and progressively move to the normal direction. As many modes are excited in a DML, the overall pattern is again a superposition of these lobes and would look omnidirectional. This would give the impression of increasing dispersion with frequency and thus diffuseness, as the radiation pat tern becomes increasingly lobulated.
(...)
2.2.5 Room Interaction and Sound Localization
The reaction of diffuse sources, such as DMLs, to room boundaries is less severe than traditional piston loudspeakers.
(...)
DML sources produce room reflections that are less correlated to the direct sound than those radiated from piston sources and thus, constructive and destructive interference of sound is minimized.

best,
graaf

[markus76]

What's unorthodox about Carlsson speakers? I read the "Ortho- Acoustic Loudspeaker" paper (http://www.carlssonplanet.com/downlo...sson_ortho.pdf). The OA5x tries to mimic a flush mounted speaker and comes with some built-in absorber panels to kill first reflections.

[Key]

Originally Posted by markus76

Well, Blauert wrote about that some 40 years ago...

Jens Blauert "Spatial Hearing"

I'm sure lots of people have noticed this. I'm not fooling myself into thinking that what I am experimenting with is cutting edge or anything. It's not exactly new but maybe the specifics and just putting all the pieces together in a way that actually works that might be somewhat new.

[graaf]

Originally Posted by markus76

Well, Blauert wrote about that some 40 years ago...

Jens Blauert "Spatial Hearing"

o yeah, 40 years ago...
and yet...

Originally Posted by markus76

...The influence of reflections is not fully understood. Everybody is guessing and declares his own experience the truth.
Toole himself asks the right questions in his AES paper "Loudspeakers and Rooms for Sound Reproduction—A Scientific Review". There is strong evidence that number, spectrum, angle, level and delay of single reflections are the key. We just don't know yet what the important properties are and how to measure them.

"Blauert wrote" yet we still do not know
yet somehow we know that "that cannot work, this is nonsense" etc. etc.

[markus76]

Originally Posted by graaf

yet somehow we know that "that cannot work, this is nonsense" etc. etc.

? You should read less between the lines...