What is a tapped horn subwoofer?

[djk]

"I know what an octave is in singing terms, but what does that look like in frequency response "

Same thing really.

Middle C is 256hz, and octave up would be 512hz, an octave down would be 128hz.

"and why (if it can be explained simply) is it limited to 2 octaves?"

Phase cancellation.

Here is a design for home use, while it is ruler flat from 40hz~125hz or so, and looks within ±3dB to 400hz, it's not going to sound the best above about 125hz due to the phase (not shown here).

Here is another one for PA that looks OK, about ±1.5dB from low C (32hz) and up two octaves (128hz)

While it looks OK to 150hz, its phase gets funny above that dip around 132hz.

 

[Silent Screamer]

thanks djk based on the figures you have provided I can extrapolate that bit further. I can now see why higher frequency drivers cover a greater range.

16Hz - 32Hz = 1 octave
32Hz - 64Hz = 1 octave
64Hz - 128Hz = 1 octave
128Hz - 256Hz = 1 octave
256Hz - 512Hz = 1 octave
512Hz - 1024Hz (1kHz) = 1 octave
1024Hz - 2048Hz (2kHz) = 1 octave
2048Hz - 4096Hz (4kHz) = 1 octave
4096Hz - 8192Hz (8kHz) = 1 octave
8192Hz - 16384Hz (16kHz) = 1 octave
16384Hz - 32768Hz (32kHz) = 1 octave

AndrewT's point now makes more sense as 40-160 and 20-80 both cover 3
octaves.

 

[tb46]

Hi,

20-40 40-80 80-160. Three octaves are from 20-160.

Regards,

 

[Etocynned]

An octave is doubling or halving of frequency. 20-40hz, 10khz-20khz.

i think they are bandwidth limited because you trade bandwidth for linearity and efficiency.

its the same with ported boxes, you trade bandwidth for efficiency and linearity.

 

[Silent Screamer]

Ok I was going to say those bands (20-40, 40-80, 80-160) don’t line up with what djk said, but then I realise you don’t have to start and stop your octave with C. So you can do 20-80, as it is only 2 octaves…

 

[bentoronto]

That's the last measured response of my POC TH with the "dogfood duct" mod. No EQ was added. The duct basically eliminated the notch at the upper end of the TH's passband and extended it a bit as you can see. It might be possible to get even better results by emulating the system in AkAbak and adjusting the length, width and location of the duct to flatten the response even further.

For more information, see The Subwoofer DIY Page v1.1 - Projects : "Proof of Concept #2"

"Dogfood duct" does that make it like a multi-resonant Karlson???

Hand-picked resonances, like they say about graphs, give me enough terms in my equation and I can draw an elephant... and wag its tail."

Ben

 

[engelheimer]

Helmholtz Resonator?

I built these years ago and thought they may fit in the tapped horn family. Remember nobody seemed to know the origin of the design back then.

They are resonant @ 110HZ (A2) and noted would blow out a lighter, the one with a 1.5" front baffle, it would do it 12 ft away.

Loaded e'm with Eminence Kappalite 3010HO's and used an ICEpower300ASC, they really seemed like some kind of air pump.

Any info or history of this design would be appreciated.

 

[Brian Steele]

Looks like some sort of slot-loaded 6th order BP. It should be possible to model it using Hornresp.

 

[bjorno]

..would blow out a lighter, the one with a 1.5" front baffle, it would do it 12 ft away.

Any info or history of this design would be appreciated.

Hi engelheimer,All

This Design made me thinking of a Picture I made for another Thread but forgot to Post:

b🙂

 

[bjorno]

Hi All,
Discard the Picture hereabove.
Picture Update: Made a more readable One + Edited the Calculation Errors I found due to unintentional Variable mixing (Easy to overlook in MathCad 🙁).

b🙂

 

[BYOaudio]

great explanation, now i get the additive nature of the tap. thanks!