Can someone give me a simple definition of what a tapped horn sub is?
I did a search for examples of them so I'm not looking for links to builds that dont talk about the simple definition of what one is.
I did a search for examples of them so I'm not looking for links to builds that dont talk about the simple definition of what one is.
A broad generalization would be that the tapped horn is a configuration where the driver radiates energy into the horns throat, a horn which expands along it's length, the tap is where the other side of the same driver's cone is radiating into a portion of the horn typically near the mouth/exit.
A sub-bass or sub-woofer is a speaker designed to deliver output below audible bass frequencies.
By definition these frequencies can be felt, but not heard.
Low bass speakers are generally used to deliver output above the Audible lower frequency limit.
Many commentators get sub & low completely mixed up and interchange them.
By definition these frequencies can be felt, but not heard.
Low bass speakers are generally used to deliver output above the Audible lower frequency limit.
Many commentators get sub & low completely mixed up and interchange them.
Low frequencies can be heard, as well as felt, as can easily be verified with a set of headphones.
Less than 80 dB SPL is required for average ears to hear 20 Hz.
At levels approaching 140 dB, low frequencies can be heard through the ears down to a few Hz.
"Sub" means below. A sub-woofer, by definition, is a woofer that is added to provide response below the woofer.
A "woofer" may have response only extending to 100 Hz or so for a small bookshelf speaker, or response reaching flat to 40 Hz or below in many designs.
For the OP, to expand on Neo Dan's explanation of the TH, a TH is a resonant air column effectively using both sides of the speaker cone, which can result in an output around 6 dB more than the same speaker (of the proper parameters) used in a bass reflex cabinet.
Unlike a "normal" horn, the so called TH does not require a large mouth exit to have flat response in it's pass band.
Interference between the front and rear speaker radiation limit TH to a bit over two octave range of reasonably flat response, generally limiting them to "sub woofer" rather than "woofer" usage.
Art Welter
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Inaudible lows are not really sub-sonic, they're infra-sonic.
Subwoofers are not sub-sonic, even using the wrong word.
Sub-woofers are more literally sub- to the woofers.
Tapped horns...well...in accessible terms I'll freely invent and use wrong...the general idea starts with a nearly typical bass horn, where the driver's 'primary" output "works" into a small space with a small opening which acts as an acoustical low-pass filter and defines the beginning of the horn throat. As the horn continues expanding along its path, it folds perhaps once or more times so that approx. the 1/2 wavelength distance along the horn the horrn wall is again adjacent to the driver. At that point the opposite-side "secondary" reverse-phase wave of the driver is now IN-phase with the "primary" output which has been delayed by a half-wavelength. In a conventional bass horn, the output of one side of the driver powers the horn and the opposite side of the driver is absorbed in a closed box. In a tapped horn, useful output is derived from both sides of the driver and added in-phase. Somewhat like the port in a bass-reflex reverses phase of the secondaray back-wave secondary output so that it adds supportively, in a TH the horn distance to the 'tap' reverses the phase of the front-wave primary output so the 'tap' adds supportively. Makes intuitive sense, if you consider the delay and phase-change as the sound travels along the horn. I have not thought about exactly how much extra output you get from the technique, but it's significant.
How you introduce the tap, shape, exactly where, how many drivers, etc. lets you use the extra "free" energy of the secondary backwave to advantages that can be traded off for bandwidth or extension rather than just efficiency, much like tuning a bass-reflex for particular objectives.
Does this help at all?
Subwoofers are not sub-sonic, even using the wrong word.
Sub-woofers are more literally sub- to the woofers.
Tapped horns...well...in accessible terms I'll freely invent and use wrong...the general idea starts with a nearly typical bass horn, where the driver's 'primary" output "works" into a small space with a small opening which acts as an acoustical low-pass filter and defines the beginning of the horn throat. As the horn continues expanding along its path, it folds perhaps once or more times so that approx. the 1/2 wavelength distance along the horn the horrn wall is again adjacent to the driver. At that point the opposite-side "secondary" reverse-phase wave of the driver is now IN-phase with the "primary" output which has been delayed by a half-wavelength. In a conventional bass horn, the output of one side of the driver powers the horn and the opposite side of the driver is absorbed in a closed box. In a tapped horn, useful output is derived from both sides of the driver and added in-phase. Somewhat like the port in a bass-reflex reverses phase of the secondaray back-wave secondary output so that it adds supportively, in a TH the horn distance to the 'tap' reverses the phase of the front-wave primary output so the 'tap' adds supportively. Makes intuitive sense, if you consider the delay and phase-change as the sound travels along the horn. I have not thought about exactly how much extra output you get from the technique, but it's significant.
How you introduce the tap, shape, exactly where, how many drivers, etc. lets you use the extra "free" energy of the secondary backwave to advantages that can be traded off for bandwidth or extension rather than just efficiency, much like tuning a bass-reflex for particular objectives.
Does this help at all?
Size is a cube function.
Dropping the response one octave and keeping the efficiency the same requires a box 8x larger.
Dropping the efficiency by 3dB will allow you to make the box half sized.
Dropping the response one octave and keeping the efficiency the same requires a box 8x larger.
Dropping the efficiency by 3dB will allow you to make the box half sized.
cyclecamper's explanation is about as good as I've ever seen, emphasizing the wavelength concept over the benefits, if any, of the little horn. He forgot to add that one of the few places that shows appreciable "respect" for this design in this very forum and critics here get messages from moderators if their skeptical posts threaten to arouse disharmony.
OK, at ONE frequency there is some boost, at another frequency there is a cut, and of course, everything in-between. Yes, it kind of resembles bass-reflex in some ways, but then some folks don't like to add resonances to their hifi.
There is much hand-tuning and art in choosing sizes and drivers and so on. Very easy to screw up and get zilch, I've heard. On the other hand, some folks are really impressed and that includes settings requiring loud or low-frequency output... albeit not necessarily quality output.
I don't think I 've ever heard a TH (or a Geddes). Pity. Any in Toronto?
Ben
OK, at ONE frequency there is some boost, at another frequency there is a cut, and of course, everything in-between. Yes, it kind of resembles bass-reflex in some ways, but then some folks don't like to add resonances to their hifi.
There is much hand-tuning and art in choosing sizes and drivers and so on. Very easy to screw up and get zilch, I've heard. On the other hand, some folks are really impressed and that includes settings requiring loud or low-frequency output... albeit not necessarily quality output.
I don't think I 've ever heard a TH (or a Geddes). Pity. Any in Toronto?
Ben
Hi,
A starting link on tapped horns @ diyaudio:
http://www.diyaudio.com/forums/subwoofers/135879-evolution-tapped-horn.html#post1702671
and another one:
http://www.diyaudio.com/forums/subwoofers/114340-tapped-horn-dummies.html
a good example:
http://www.diyaudio.com/forums/subw...ped-horn-th-spud.html?perpage=25&pagenumber=1
and the "monster" thread:
http://www.diyaudio.com/forums/subw...ped-horn-project.html?perpage=25&pagenumber=1
Regards,
A starting link on tapped horns @ diyaudio:
http://www.diyaudio.com/forums/subwoofers/135879-evolution-tapped-horn.html#post1702671
and another one:
http://www.diyaudio.com/forums/subwoofers/114340-tapped-horn-dummies.html
a good example:
http://www.diyaudio.com/forums/subw...ped-horn-th-spud.html?perpage=25&pagenumber=1
and the "monster" thread:
http://www.diyaudio.com/forums/subw...ped-horn-project.html?perpage=25&pagenumber=1
Regards,
Ben,
TH do have some passing resemblance to bass reflex, they both have less cone movement at Fb, then a rapid increase below, compared to a sealed alignment where excursion simply rises as frequency is lowered.
A poorly designed TH (or a poorly designed enclosure of any type) can have "peaky" response, but a properly designed TH can have flat response within it's passband, or, just like a sealed or BR design can be designed for a rising or falling response appropriate for it's intended use.
As far as "resonance", room resonance typically far exceeds any cabinet resonance in the several TH I have built.
Even in an outdoor setting lacking room problems, the difference in sound quality between a TH and an infinite baffle is a bit less than between an infinite baffle and a BR. TH can sound very similar to FLH (front loaded horns) but usually require less space for a given LF corner.
http://www.diyaudio.com/forums/subwoofers/184992-tapped-horn-vs-bass-reflex-case-study.html
I think there is at least one sound company using a VTC system in Toronto, the VTC uses TH for the low frequency of a three way line array also using Danley's Paraline HF loading.
Art
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I have found that with EQ there seems to be little point in the horn flare as it only seems to smooth the response and not impact final efficiancy. Anyone else using no flare? is this even a tapped horn anymore?
Tapped horns are good where money for drivers/amps is limited or maximum required output is crazy loud. I have got indoor mesurments of 137dB at the listening position with 400W power input @ 35Hz with a single 12" driver in a corner loaded tapped horn, however the down side is a box the size of a fridge and a requirment for DSP filtering to prevent overload at lower frequancies and remove high q peaks just outside the pass band.
Tapped horns are good where money for drivers/amps is limited or maximum required output is crazy loud. I have got indoor mesurments of 137dB at the listening position with 400W power input @ 35Hz with a single 12" driver in a corner loaded tapped horn, however the down side is a box the size of a fridge and a requirment for DSP filtering to prevent overload at lower frequancies and remove high q peaks just outside the pass band.
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A requirement for DSP filtering to prevent overexcursion at low frequencies is shared by IB (infinite baffle), BR, BLH and most FLH designs.
Cabinets with no flare, or negative flare, using a TH arrangement, are often called TQWP, tuned quarter wave pipe.
They are quite popular on this forum, a lower FB can be achieved in a smaller box than a TH or BR using the same driver.
There is a blurred continuum between "scoops" (BLH), TH and TQWP.
Tom Danley "did the math" and called the resultant cabinet designs TH. The name has stuck, it is catchier than DRC (dual resonant column) which is what I would call it, but no one has heard of a DRC, so I don't.
Art Welter
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There is definitely a difference in efficiency to be had between a tapped pipe and positive expansion found in a tapped horn.
Maybe your implementation is skewing the results - you seem to have the same final segment in your setup - the corner of the room?
This may seem a bit out of the blue....
I judge the goodness of speaker systems according to whether or not they'd work with driver-based motional feedback control. Driver-based motional feedback only works when there is supposed to be a simple relation between cone movement and sound output (sealed boxes, IB, some horns). Otherwise, you are trafficking in resonances.
Ben
I judge the goodness of speaker systems according to whether or not they'd work with driver-based motional feedback control. Driver-based motional feedback only works when there is supposed to be a simple relation between cone movement and sound output (sealed boxes, IB, some horns). Otherwise, you are trafficking in resonances.
Ben
Hi Art,
I used to say the exact same thing, and was wrong for saying it....
The concept of "6dB gain via the use of both sides of the driver" is a very common misinterpretation, and/or misconception about tapped horns. A tapped horn presents no significant change in gain properties per box volume above that of a horn where the rear of the driver were simply exposed as a direct radiator. By moving the position of the driver down into the throat of the horn a bit (overlapping a segment), response can be "shaped" more desirably for a given driver or bandwidth. [see cyclecamper's explanation above to see "why"] However, that "shaping" of response is just that, a "shaping," it may prove beneficial in the desired pass-band, but has little to nothing to do with the vast majority of the gain the box has over traditional vented. The primary gain over a vented design comes from an effective utilisation of increased box volume.
Regards,
Eric
well I had a look at hornresp and that says it should only get 132dB @ 1m wheras I got 137dB at 4m so there is alot of room gain in there. Pass band is 32Hz - 122Hz +/- 5dB ripple (peaks at end of pass and stop band). I don't care about how flat it is considering I have to apply loads of EQ anyway. Box volume is about 100L but I had to expand the pipe +1/3rd cross sectional area around the driver as it would unload at high SPL with lots of 'chuffing' noises around the driver. I am quite busy at the moment but its not that interesting other horns have basicly the same performance and flatter pass bands. I can post a pic in a week or so its hilariously ugly.
*the mouth pointed upwards into the room corner so its very well coupled to the corner
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