I agree that this happens only at uncommonly high levels. The point is that it won't normally be audible.. at least not in a domestic situation at any level, and it shouldn't be used as a reason to avoid one horn type over another. Not only am I questioning the amount of distortion, but it is low order distortion with it's relatively lesser significance.
i would still take a compression driver over a regular dome tweeter but i would take a ribbon array over a compression driver
as for choosing one horn over another i would just use the biggest modern horn i can afford
i wouldn't use any vintage horns or horn adapters
What about a big modern horn with a low expansion rate, as oltos has been considering?
if it has a low expansion rate it is not modern.
it may be new but it isn't modern.
much like Radian drivers are new but not modern.
it may be new but it isn't modern.
much like Radian drivers are new but not modern.
I take modern if it translates into better vice versa I take dated if modern doesn't cut it sonically. In our hobby modern is not the relevant thing.
I wish that some company would use modern equipment to give us Audiophiles a driver for domestic use. For the working man not for the privileged.
I wish that some company would use modern equipment to give us Audiophiles a driver for domestic use. For the working man not for the privileged.
are you here to moderate or troll ?
this discontinued JBL:
https://jblpro.com/en-US/products/5674
used a 4" compression driver down to 300 hz.
show me one modern commercial system using a compression driver down to 300 hz.
that JBL horn is 32" deep ( according to specs )
and the initial expansion rate is low:
for that matter the B&C horn rated for 300 hz is almost the same shape:
by comparison check out this QSC system ( SC-424 )
it uses a coaxial HF from BMS but instead of 300 hz it only works to 1.7 khz, which allows them to use a short and wide horn prioritizing wide directivity and low distortion over low end reach - then they simply use a 10" paper midrange.
this QSC SC-424 represents modern approach to design, while the discontinued JBL 5674 represents a vintage design - not just in horn shape but also in driver choice. note the JBL used titanium domes while QSC uses plastic annular diaphragms.
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I'd disagree with what actually happens in these two cases.
What is the meaning of "low end reach"?
it means that for a horn loaded driver to efficiently convert electrical energy into acoustical you want the air load mass to roughly match the diaphragm mass which means at a frequency you're trying to reproduce the driver should feel a fair amount of resistance from the air due to inertia of that air ... this is only possible if the relatively straight portion of the horn throat is of length comparable to at least say 1/8th of wavelength ... so at 300 hz the wavelength is 45 inches which means the first couple of inches of the horn throat would have to see little expansion otherwise there will be little acoustical load at that frequency and thus no way to produce high output there ...
if the horn expands rapidly right from the start then it becomes too easy to move the air at low frequencies - the air is moved without creating pressure - which is good for lowering distortion due to compression but bad for actually reproducing those low frequencies ...
essentially due to exponential shape of the horn, to the driver the horn looks wider to low frequencies and narrower at high frequencies - if you optimize for low frequencies by keeping it narrow and long you get too much compression and distortion in highs ... if you optimize for low distortion and wide directivity in highs you lose efficiency in the lows ...
so "low end reach" means optimum efficiency at lowest frequencies ... which modern designs give up because it's better to just use a paper midrange there and instead get better HF performance.
there is a dip in hearing sensitivity around 1.5 khz and that's about where you want your crossover from a paper cone to the horn to be. QSC has it at 1.7 khz. a modern JBL design has it at 1.2 khz:
https://jblpro.com/en-US/products/4732#specifications
the next dip in hearing sensitivity is around 10 khz which is why BMS puts their co-axial crossover at around 7 khz ...
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So you mean reach to a low frequency, not reach into the room by some distance?
Fast opening horns have some favourable low frequency properties compared to slow opening of the same overall dimensions.
What of cutoff..?
Fast opening horns have some favourable low frequency properties compared to slow opening of the same overall dimensions.
What of cutoff..?
Dissident Sound "low end reach" meant "optimum efficiency at lowest frequencies".
Sound in free air drops off at 6dB per doubling of distance, the distance it reaches at "X" SPL is determined by driver/horn sensitivity- if 6 dB more sensitive/efficient, it can cover double the distance at the same input power level.
A "fast opening horn" would have a higher Fc (or lack a specific Fc) than a slower opening horn of the same overall dimensions.
What favorable low frequency properties would raising Fc provide?
Art
If greater efficiency means wider dispersion then this doesn't help sensitivity, but even if it did, ...
..you'd have to EQ it down or it would be too loud. So I don't understand why you'd suggest this.
Waveguides don't "cutoff". For horns that do you have to stay away from the low end.
They do, but more gradually (in the case of an OSWG).
To quote Bjørn Kolbrek:
"The OS waveguide does not have a sharp cutoff like the exponential or hyperbolic horns, but it is useful to be able to predict at what frequency the throat impedance of the waveguide becomes too low to be useful. If you set this frequency at the point where the throat resistance is 0.2 times its asymptotic value, so that the meaning of the cutoff frequency becomes similar to the meaning of the term as used with exponential horns."
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Would you say there is a difference in sound when you run down through this region? If so, how would you describe it?
Is horn efficiency an important factor with a waveguide?
Cutoff is being given two meanings here and people are assuming it implies something. Does it?
Is horn efficiency an important factor with a waveguide?
Cutoff is being given two meanings here and people are assuming it implies something. Does it?
the difference between horn and waveguide can be somewhat moot unless there is either compression or folding involved - then you know it's a horn
i mean a flat baffle is also a waveguide if you think about it
i guess the difference between horn and waveguide is a horn is intended to boost output at all frequencies at which a driver operates while a waveguide may boost some frequencies and not others and is intended to control directivity instead
but in the end whether it's a baffle, a waveguide or horn it's a boundary that creates acoustical loading and affects frequency response, efficiency and directivity.
it's just what with baffles we focus on edge diffraction / baffle step. with waveguides we focus on upper frequency directivity and with horns on frequency response.
but those are just limitations of our mental models - they aren't real distinctions. if some Finite Element Analysis software had to model those things it would use the same exact math to model a baffle, a waveguide and a horn. because in the end air is air and boundary is boundary.
we have to make artificial distinctions in order to come up with useful approximations that keep the math down to something we humans can work with because our ability to do math is MANY orders of magnitude below that of computers ...
but ironically as the power of computers grows the math they use is getting simpler ... because the level of abstraction required to solve a problem is getting lower ... with enough processing power things can be modeled directly without approximation which is more number crunching but fewer formulas ...
Yes, try to listen/or measure.
It has been proven time and time again in this forum over the years.
A Faital HF108 cannot be crossed (without severe penalties) below 700-800 Hz with an OSWG > the original Geddes design, not Mabat's ATH variants.
But you can cross the same driver at 600-700 Hz with a Yuichi A-290 or an Electro-Voice HR9040.
That said, I think an OSWG is suitable in combination with 8 and 10" woofers, crossed between 1000-1500 Hz
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No. You can't bring up running out of excursion because that's just obvious and misses the point.
My question is about the horn, not the driver...
My question is about the horn, not the driver...
Kolbrek doesn't say anything in that quote that answers what I asked. In fact, the last sentence appears malformed so it looks as though the quote is incomplete.
Quite the contrary, at cutoff an exponential horn has no output but that's not a concern with an OS waveguide, is it?
Quite the contrary, at cutoff an exponential horn has no output but that's not a concern with an OS waveguide, is it?