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09-16-2007 Post mapped to one branch of Knowledge Tree
Romy the Cat


Boston, MA
Posts 9,616
Joined on 05-28-2004

Post #: 1
Post ID: 5317
Reply to: 5317
Proximity of horn’s crossover and it’s ability to care over-amplitude.

 Romy the Cat wrote:
Make an experiment, and I will simplify the case quite assertively. Take a typical compression driver, cross it at 800Hz, second order and load it into a proper contemporary horn (Tratrix or JMLC) of 300Hz. Listen that horn, you will get some sort of sound that let accept as OK Sound. Now begin to very slow lower the crossover point and keep listening the channel. While you lowering the crossover point, somewhere around 550Hz (I took this number purely arbitrarily as it would depends from VERY MANY circumstances) the horn will begin to demonstrate what I call “choked sound”. The “choked sound” is HOW HORNS SOUND IN 99% OF ALL HORN INSTALLATIONS OUT THERE – people just too damn to deal with it. The “choked sound” is the satiation when Sound produced by a driver can’t be “processed” by horn. In this “choked mode” a horn produces the “sonic boom” that was made by the horn’s bell and that “sonic boom” screw up the enter band-pass of the channel - the game is over.  Increasing of the crossover point for ¼ octave (for instance) will fix the situation - so we have approximately one octave between horn’s rate and mix crossover point…
After many listing tests and experiments and discovered a very interesting behavior.  It is so predictable and so stable that I declare is as a new Rule. So:

The proximity of crossover point to the horn rate is related (besides being related to many other things) to the ability of the given channel to mask out the amplitude imperfections.

A brief explanation: pretend we have a 300Hz horn and 600Hz 6dB crossover or one octave gap; also we have 300Hz horn and 450Hz 6dB crossover or 1/2 octave gap. The channel with one octave gap has +/- 12bB in its band-pass. The channel with 1/2 octave gap has +/- 6bB in its band-pass. Here is where the Rule is applied: both channels will have an identical impact from the perspective of response flatness. The larger horn gap masks out subjective perception of amplitude’s peak and dips. The Rule is NOT depending from the bandwidth of the channel and works all the way down of the auditable region. (Though I presume that at the region of frequencies, wavelength of which is co-measurable with throat diameter) other things will override the Rule)

Rgs, Romy the caT


"I wish I could score everything for horns." - Richard Wagner. "Our writing equipment takes part in the forming of our thoughts." - Friedrich Nietzsche
01-23-2008 Post does not mapped to Knowledge Tree
Romy the Cat


Boston, MA
Posts 9,616
Joined on 05-28-2004

Post #: 2
Post ID: 6405
Reply to: 5317
The horn choking is property of…. volume?

I spoke about the minimum proximity of a crossover point to the horn rate but there was one very fine point that I did not address and that I never have seen voiced. We have a horn and the driver of the horn is properly crossed, far enough to escape the horn choking and the “sonic boom”. There are many factors that would describe the reason of the minimum proximity (drivers type, horn curve type, crossover type and any other) but among all factors one is always overlooked – the reference volume.

It is paradoxical but with increase volume of signal the minimum proximity between crossover point and horn rate increases. I would hardly be able to put it in any kind of formulation but subjectively I feel that we lose 1/3 octave of proximity with each 6dB. I do not know what would be an explanation of the phenomena but the phenomenon is there.

The Cat


"I wish I could score everything for horns." - Richard Wagner. "Our writing equipment takes part in the forming of our thoughts." - Friedrich Nietzsche
01-23-2008 Post does not mapped to Knowledge Tree
Paul S
San Diego, California, USA
Posts 2,181
Joined on 10-12-2006

Post #: 3
Post ID: 6409
Reply to: 6405
Does this explain or relate to the "trombone" effects?
VERY interesting observation, Romy.

I fought with but was unable to overcome both dynamic "tromboning" and also a closely-related sort of "shaping" effect, and now I wonder if this relates to the "proximity effect".

I did limited experiments with crossovers, horn profiles and materials, and also with adding and subtracting material from the inside of the horn.  I was not surprised that this affected the sound, but I was very surprised by how little it could take to affect the sound a lot.

From my reading here I have learned a lot more about tuning a horn, although not nearly enough for confidence to go all out with it yet, especially given the overall complexity and the cost.  The last thing I want is an expensive pile of horns that sound like horns, and this is all I've ever heard, to date.

Funny that you are the ONLY horn lover I am aware of who even acknowledges these things, let alone discusses them freely and intelligently.

I did not get my hopes up when Steve invited me to hear the Cogent system, so I was not really let down by it, either.  In fact, I was actually encouraged by what they got very right, indeed.  Still, I would love to connect with anyone in southern California who has overcome the horn problems, because this is obviously the only way to get the last word in overall dynamics.

Best regards,
Paul S
Page 1 of 1 (3 items) Select Pages: 
   Target    Threads for related reading   Most recent post in related threads   Forum  Replies   Views   Started 
  »  New  Adding one more spherical to Macondo...  It is about magnet and SS type....  Horn-Loaded Speakers Forum     92  741675  05-23-2006
  »  New  Big mama 1.5" horns......  Crossover point...  Horn-Loaded Speakers Forum     27  168944  09-08-2006
  »  New  Phase plug for midbass..  Ulf plug...  Horn-Loaded Speakers Forum     23  254919  11-08-2006
  »  New  Macondo's Axioms: Horn-loaded acoustic systems..  No wonder...  Horn-Loaded Speakers Forum     72  429282  07-29-2007
  »  New  Jessie Dazzle Project..  Will this better to be auditable?...  Horn-Loaded Speakers Forum     172  1209405  08-03-2007
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