i have a feeling that i will get in trouble for this (because to older people thinking often equals heresy) but im going to say this anyway
i just read this little white paper on tapped horns and im just so not buying it ...
i dont know if i should even go into details on why this is just marketing hype ?
in any case i have developed a better technology some time ago ... much better. i even posted about it on madisound.com forum but nobody seems to have understood it.
my technology couples the front of of the driver to a horn and the rear to a bandpass box filled with damping material.
this damped bandpass box acts as a low pass filter and a phase shift for the rear wave. the rear wave is neutralized at frequencies where it would have caused destructive interference. it is allowed out at frequencies where it would cause constructive interference. it vents the pressure at the lowest frequencies allowing a lighter cone and more efficient driver. and last but not least by shifting the phase at the predetermined point its extends the frequency range in which the summation is constructive.
i know that to most people the very idea of questioning any accepted views is absolutely terrifying ... but i don't care ... many "scientific facts" are eventually proven false ... and the only reason these things are considered "facts" in the first place is because people are too intellectually lazy to question them ... then people can laugh at their ancestors for thinking the earth is flat when if they were in their place they would too burn the heretic who had the audacity to reason
i just read this little white paper on tapped horns and im just so not buying it ...
i dont know if i should even go into details on why this is just marketing hype ?
in any case i have developed a better technology some time ago ... much better. i even posted about it on madisound.com forum but nobody seems to have understood it.
my technology couples the front of of the driver to a horn and the rear to a bandpass box filled with damping material.
this damped bandpass box acts as a low pass filter and a phase shift for the rear wave. the rear wave is neutralized at frequencies where it would have caused destructive interference. it is allowed out at frequencies where it would cause constructive interference. it vents the pressure at the lowest frequencies allowing a lighter cone and more efficient driver. and last but not least by shifting the phase at the predetermined point its extends the frequency range in which the summation is constructive.
i know that to most people the very idea of questioning any accepted views is absolutely terrifying ... but i don't care ... many "scientific facts" are eventually proven false ... and the only reason these things are considered "facts" in the first place is because people are too intellectually lazy to question them ... then people can laugh at their ancestors for thinking the earth is flat when if they were in their place they would too burn the heretic who had the audacity to reason
To this older person it would appear, based on the statements above, that you are not thinking. You are dreaming without any real substance behind the "idea". Thinking is when you take the idea to the next level and can define and present the pro's and con's. I have new ideas of my own to think about, but at my advanced age I cannot take on too much more by also doing your thinking. You know my biggest complaint about the younger people in the hobby is that they don't want to do any of the hard thinking themselves, they want others to figure out the solutions to the problem and spoon feed the results back. I hope you prove me wrong.
I thought that with Bandpass systems, the driver saw a very stiff air load in band, and hardly moved at all as a result. Isn't this the opposite of what you want for the horn driver?
Or are you planning to tune the bandpass much lower? In that case it just looks like a damped sealed chamber in the horn operating band.
I think you need to at least make a simple analytic model - the formulas for bandpass designs are well known (see for example http://www.diysubwoofers.org/) It isn't clear that your two aims (nice in-band loading for the horn driver, and bass reinforcement) are mutually compatible - what tuning frequency are you targetting for the band pass?
Or are you planning to tune the bandpass much lower? In that case it just looks like a damped sealed chamber in the horn operating band.
I think you need to at least make a simple analytic model - the formulas for bandpass designs are well known (see for example http://www.diysubwoofers.org/) It isn't clear that your two aims (nice in-band loading for the horn driver, and bass reinforcement) are mutually compatible - what tuning frequency are you targetting for the band pass?
Eva said:
as far as construction it would be just that - a vent in the rear enclosure. but the purpose would not be to use the vent as a resonator but as a lowpass filter and in fact the damping could be used to make sure the resonance itself is suppressed and only the lowpass behavior remains ... so it would be operated below the "tuning" frequency and not above it.
A bandpass box receiving radiation from only the driver's rear?
u mena liek... a vented boxx? with a horn on the front?
I have a 30+ year old yamaha box sitting in my basement that has a similar topology.
If you'd like, you can come pick it up, measure it, and then you won't even have to model or build your new technology.
Joseph Decker
u mena liek... a vented boxx? with a horn on the front?
I have a 30+ year old yamaha box sitting in my basement that has a similar topology.
If you'd like, you can come pick it up, measure it, and then you won't even have to model or build your new technology.
Joseph Decker
Peter M. said:Please post about your new and better technology and how it works. It is very possible that I don`t understand it, but there are a lot of sharp brains on this forum.
Best regards,
Peter
ok so you start with a quarter wave horn. and you look for a way to deal with the rear of the driver. the obvious solution is to just put a sealed box around it ... that works ... but it also uses space and does not use the rear wave for anything positive.
so the objectives are then
1 - reduce the size of the box enclosing the rear of the driver
2 - use the energy from the rear wave to add to that of the main output of the horn
3 - avoid any nulls or dips in response from the out-of-phase summation of the two waves
for that we put a vent in the box enclosing the rear of the driver in this quarter wave horn ... but instead of tuning the vent to the 1/4 wave frequency we tune it much higher ... perhaps to 3 times higher.
so what happens is the front wave is delayed 3/4 wave and the rear wave is delayed 2/4 wave (from just the fact that its inverted) and another 1/4 wave from passing through the vent ... so both waves arrive in-phase.
at a lower frequency the front energy is delayed 2/4 wave and the rear is also delayed 2/4 wave (due to inverse of polarity) but not delayed much more by port because it is already in the ports passband so again both waves sum in phase
at 1/4 wave frequency the front and rear waves neither reinforce nor cancel ....
at above port tuning frequency there is no rear wave any more because its all been killed by the box with damping ...
so the summation is either non-destructive or constructive or there is none throughout the entire usable range of the horn ... and if you refer to our 3 objectives they have all been met.
Joseph Decker said:
i didnt say my technology was new. i said i developed this idea and posted it on madisound forum and got no response.
however to me "vented" is a box that is operated above tuning frequency and my box would be operated below it so i would not call it vented
im not sure what your yamaha does. it may be what i am describing or it may be something else.
I understand, but the vent rotates phase 180 degrees near resonance and goes back to 0 degrees below resonance. You would need a horn producing full 360 degrees of phase shift at the frequency where the vent resonates. and still 180 degrees below resonance to get some summing. This calls for a very long expansion (one wavelenght of tnuning freq).
It shouldn't be hard to simulate with hornresp, the pity is that it doesn't allow you to set vented chamber Q and it assumes a too high value.
It shouldn't be hard to simulate with hornresp, the pity is that it doesn't allow you to set vented chamber Q and it assumes a too high value.
Eva said:
so lets say the vent is 100hz
then at 20 hz it will add roughly zero phase shift
at say 1000 hz the vent will delay the phase by about 90 degree ...
why do you say there will be 180 degree at 100 hz ?
the vent itself is an inductor ... all by itself it should not produce more than 90 degree shift but when coupled to the box (box being a capacitor) i am not sure what will happen at resonance BUT ! as i said the resonance itself can be controlled by damping as we do not need the resonance at all ... we just need the low-pass and phase-shift behavior of this inductor ...
PigletsDad said:
ok lets not hijack this into bandpass enclosures but as far as air loads go my philosophy is this:
1 - without airload there can be no energy transfer.
2 - the more airload the more kinetic energy of the driver can go into air
3 - the driver should be more strongly coupled to air on the side which is the "output" side to make sure the energy transferred to air is used as opposed to wasted
(3) tells you why horns will always outperform direct radiators. its because horns load the driver on the "active" side as strongly as other alignments load it on the side which is not used. however to take this philosophy to its ultimate conclusion after loading the front of the driver you have to unload its rear ... which is what my proposed alignment does by using a vent as a sort of bypass valve.
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