New project 400WRMS folded horn bin.

How Low, does it go?

The speaker goes down to 35Hz.
But I have no way of testing it in the box.


Nominal Chassis Diameter 15” / 381 mm
Impedance 8 Ω
Power Handling 600 w (A.E.S.)
Peak Power (6dB Crest Factor) 2400 w (A.E.S.)
Usable Frequency Range -6dB 35 Hz - 3.5 kHz
Sensitivity (1 w - 1 m) 98 dB
Moving Mass inc. Air Load 89 grams
Minimum Impedance Zmin 6.5 Ω
Effective Piston Diameter 13.03” / 330.96 mm
Peak Displacement Volume of Cone Vd 0.59 litres
Magnet Weight 100 oz
Magnetic Gap Depth 0.39” / 10 mm
Flux Density 1.1 Tesla
Coil Winding Height 0.75” / 19 mm
Voice Coil Diameter 3.0” / 76.2 mm
 
This style cabinet will both limit how low and how high the speaker is able to play. Both 35 Hz and 3500 Hz sound way out of it's intended band width. A simple way to get a general idea is too play a sine sweep from either a sine sweep generator or some sine sweep video posted on youtube and listen where the music start too drop off.

Johan
 
I connected the speaker to a signal generator and it plays fairly flat up to 3.8KHz.
And down to 40Hz.

Not likely. Probably measuring/hearing cabinet resonance because there is no way that horn goes that high. The efficiency-bandwidth product is only 210Hz for that woofer.

Flc = lower rolloff due to driver compliance
Fhm = high end rolloff due to driver diaphragm mass
Fhvc = high end rolloff due to voice coil inductance
Fhc = high end rolloff due to the compliance introduced by the front chamber

Attached graphic is from D.B Keele's AES paper titled "Low-Frequency Horn Design Using Thiele-Small Driver Parameters".
 

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I have it connected to my pc through a USB DAC and it sounds fine.
Its definitely going much higher than 210Hz.

I have a full range speaker next to it and they don't sound much different from the same signal source.


Way back in 1976 I worked for a disco who bought a pair of Orange folded horn speakers.
They sounded pretty much the same as mine but they had tweeters in them.


FS Hz 40 Hz
RE Ohms 6.5 Ω
Qms 8.8
Qes 0.38
Qts 0.37
Vas Ltr 188 litres
Vd litres 0.59 litres
CMS (mm/N) 0.18 mm/N
BL T/m 19.7 T/m
Mms (grms) 89 grams
Xmax (mm) 6.9 mm
Sd (cm2) 856 cm2
Efficiency % 3.05%
Le (1k Hz) 1.85 mH
 
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The fact of the matter is it's extremely unlikely a short horn like that plays "fairly flat" between 40 and 3.5khz. I recognize from your posting history that you are very much a by-ear speaker builder. Certainly nothing wrong with that, but realize that does limit your ability to both predict and evaluate cabinet performance.
 

wg_ski

Member
2007-10-10 5:21 pm
Power response extends to 210 Hz - but that doesn't mean that something above that won't come out. Probably not very flat above that 210 Hz. High Q resonant peaks can make a speaker sound very "loud" - that's what guitar speakers are supposed to do. So if there is a general roll off starting at a few hundred Hz, but a peaky response up there, it can "sound" like it goes "much higher". Until you compare it with a speaker that has decent power and off-axis response up there.

Use a "shouty" speaker like this and they'll be telling you to turn down the music, but turn up the bass.
 
I have been building speakers since 1977.
Mostly for disco and/or guitar.

Until recently most of my boxes were simple sealed boxes which functioned very well.
I never got any complaints while performing about the sound.

I don't have the equipment for plotting exactly the output of my speakers.
The folded horn design was pinched from a Fane diagram.
I just widened or narrow the box to suit the speaker I was using at the time.

I will admit the folded horns do need tweeters for top end and I have a couple of Pyle high power tweeters to go with them.

I am also a musician so I don't think my ears are too bad, although at my age the top end is missing, I lose everything above 10KHz.
 
Power response extends to 210 Hz - but that doesn't mean that something above that won't come out. Probably not very flat above that 210 Hz. High Q resonant peaks can make a speaker sound very "loud" - that's what guitar speakers are supposed to do. So if there is a general roll off starting at a few hundred Hz, but a peaky response up there, it can "sound" like it goes "much higher". Until you compare it with a speaker that has decent power and off-axis response up there.

Use a "shouty" speaker like this and they'll be telling you to turn down the music, but turn up the bass.

It definitely outputs a tone at 3.8KHz but dies off very quickly above that.

I have to add that I am testing at about 1 watt and its likely the speaker wont do as well frequency wise at full power. That's why I am using tweeters with it.

I previously bought a pair of Fane folded horn speakers off a guitarist and he used two tweeters with them to get top end.