That reads like a script to a really bad informercial. 3 paragraphs in, it's painful to continue.
Sorry, but I have to agree.
Maybe if it got to the point a little more quickly.
Dave
He dosnt have a clue. That whole paragraph on transient response is wrong. DC is needed for proper transient response? Laughable. Why do so many people think a subwoofer has to be fast. It only has to be fast enough to reproduce 120 hz. The transients in the music are higher freqs.
Seriously?
Seriously???
Wow... 😉
All kidding aside, what is it you find so amazing about the "review"? Is it that you are the author? 😉
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Yes, very long. He could have said that's a fan that blows air about in a cocoon or an image maybe.
Interesting concept, never heard of before... 😉
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Hi,
No, he is clueless, and full of turgid garbage.
What that implies about your critical facilities and actual
knowledge of the subject I'll let you work that one out.
rgds, sreten.
FWIW I fully "get" what PC is up to in his reviews,
which are aimed at the technically illiterate who
like "ideas" about audio much more than facts.
As_for_the_idea_bass_is_slow,what_is_the_risetime_on_the_fundamal_of_a_cannon_shot?
Bass_is_not_slow,transient_response_is_frequency_independant.
The_article_is_sound,wordy,but_sound.
If_you_can_find_and_debunk_a_statement_do_so.
I_understand_newtonian_physics_quite_well_and_while_it_took_some_research_to_grasp_how_he_presented_his_poiint_of_view,I_found_no_fault.
Bass_is_not_slow,transient_response_is_frequency_independant.
The_article_is_sound,wordy,but_sound.
If_you_can_find_and_debunk_a_statement_do_so.
I_understand_newtonian_physics_quite_well_and_while_it_took_some_research_to_grasp_how_he_presented_his_poiint_of_view,I_found_no_fault.
Hi,
What do think the risetime of that Fan subwoofer is ?
What do you think is its upper frequency limit ? Caused by what ?
What do think the rise time of a signal low passed at 20Hz 24dB/oct L/R is ?
(The recommended x/o frequency and likely filter for the fan woofer.)
Yes its good below 20Hz but I already know that. I know how it
works and how normal subs work. I don't need pages of BS
expounding on the differences to tell me stuff I already know.
rgds, sreten.
What do think the risetime of that Fan subwoofer is ?
What do you think is its upper frequency limit ? Caused by what ?
What do think the rise time of a signal low passed at 20Hz 24dB/oct L/R is ?
(The recommended x/o frequency and likely filter for the fan woofer.)
Yes its good below 20Hz but I already know that. I know how it
works and how normal subs work. I don't need pages of BS
expounding on the differences to tell me stuff I already know.
rgds, sreten.
Hi chaps,
I seem to remember that this topic was covered a LONG time ago, nevertheless, I'd like to (again 😛) shove in myFWIW, IMHO etc.
Please feel free to assassinate me for suggesting so, but notwithstanding the “review” (for which I ran out of steam following the first million witless words), the TR-17 is essentially a fish trying to ride a bicycle. Way over-complex, and moreover, to what end? A helicopter speaker? Really??!!
Please humour the following, and my apologies if it comes across like a rant; it's meant as a well humoured observation:
There is nothing musical beneath 16Hz, so the only argument for fidelity down to DC would really be relegated to the commission for undertone involvement (same as the argument for super-tweeters affecting bass & midrange elements) or drama (AV effects). At this price you could bolt huge solenoids to your floors, walls & ceilings and get a much more dramatic effect if your looking to rattle yourself to death watching the latest shoot-em-up or 'trekkie. Moreover, think how many Pro-drivers you could buy for this money & simply roll them off >10Hz.
You can't actually hear 16Hz, you tend to feel it in your neck - by the time you've wound up the volume enough to hear it you'd have in all likelihood seriously damaged your ears. Furthermore, what source material is going to deliver that kind of frequency? I don't know of anything that will give you much sense below 10Hz unless you re-process the source material: not exactly HiFi!
IMHO (ahem..) the 3% distortion figure is simply a joke. Everybody & his dog knows that unless you roll off (or oversample) a CD @ 20KHz you get pretty much a square wave: 100% distortion or thereabouts, unless you fed a square wave in which is what you'll get whatever you put in. In this instance you use an acoustic labyrinth to kill everything over 20Hz and (duh!) of course you can hit <3%, you could accomplish that by repeatedly hitting the start of the labyrinth with a dead cat!
OK, not trolling here & I hope I delivered a few chuckles; but let's (for the sake of playing chess with ones self...) assume that there is merit in accurately delivering a measurable signal down to DC without shorting the local sub-station. I hope this doesn't start sounding like that review...
How do these subs work? They use a fan (DC) to cause pressurisation (amplification) and vary the frequency by oscillating the pitch of the blades. I won't go into the negative aspects, you can do this yourself by placing your hand in front of an ordinary fan – apart from the noise you'll notice that the air-flow is far from smooth.
How do horns work? They pressurise the air in front of a diaphragm in order to realise a 1:1 theoretical acoustic impedance at the mouth. Diaphragm weighs more than air, but can match the effective weight of pressurised air causing amplification (under oscillation).
I remember my late father once told me about an intriguing PA system that used to be prevalent in the 1930's, way before amplification could sensibly produce anything to upset the neighbours. A small van in the shape of a motor-tricycle would turn up to a venue in order to squawk at visitors: the van was essentially a horn with the mouth opening at the rear. What makes the scenario interesting applies to the greater portion of amplification involved; yes, there was a small maybe <1W amp to move the diaphragm, but relate back to the identical points eluded to in the above two statements: pressurisation = amplification under the right circumstances.
These curious little vans ran a compressor line to the throat of the horn, just in front of the diaphragm. The higher the compression, the louder the horn – simple eh?
So what?
My point is this: rather than rigging up a ludicrously elaborate fan, why not simply pressurise an ordinary driver? You need to pressurise front and rear, and mount in such a way that the rear flow can be terminated/negated – same as the fan. Obviously you need front and rear pressure chambers to enable pressurisation in the same manner as a horn throat, but the pressure delivered by an appropriate airline does the job of the horn mouth – you shouldn't actually need a horn as we know it. And yes – get it right & it'll go down to DC. Further more, you have two modes of amplification: first is your driving amplifier, second is the rate of airflow which provides the required pressure...
All of the above can be achieved at a fraction of the cost of the TR-17, and frankly if you can physically afford the TR-17 along with it's installation, you can do the above. I'll guarantee you'll get <3% distortion 😛 & who knows, maybe it'll play higher than 20Hz...
I seem to remember that this topic was covered a LONG time ago, nevertheless, I'd like to (again 😛) shove in myFWIW, IMHO etc.
Please feel free to assassinate me for suggesting so, but notwithstanding the “review” (for which I ran out of steam following the first million witless words), the TR-17 is essentially a fish trying to ride a bicycle. Way over-complex, and moreover, to what end? A helicopter speaker? Really??!!
Please humour the following, and my apologies if it comes across like a rant; it's meant as a well humoured observation:
There is nothing musical beneath 16Hz, so the only argument for fidelity down to DC would really be relegated to the commission for undertone involvement (same as the argument for super-tweeters affecting bass & midrange elements) or drama (AV effects). At this price you could bolt huge solenoids to your floors, walls & ceilings and get a much more dramatic effect if your looking to rattle yourself to death watching the latest shoot-em-up or 'trekkie. Moreover, think how many Pro-drivers you could buy for this money & simply roll them off >10Hz.
You can't actually hear 16Hz, you tend to feel it in your neck - by the time you've wound up the volume enough to hear it you'd have in all likelihood seriously damaged your ears. Furthermore, what source material is going to deliver that kind of frequency? I don't know of anything that will give you much sense below 10Hz unless you re-process the source material: not exactly HiFi!
IMHO (ahem..) the 3% distortion figure is simply a joke. Everybody & his dog knows that unless you roll off (or oversample) a CD @ 20KHz you get pretty much a square wave: 100% distortion or thereabouts, unless you fed a square wave in which is what you'll get whatever you put in. In this instance you use an acoustic labyrinth to kill everything over 20Hz and (duh!) of course you can hit <3%, you could accomplish that by repeatedly hitting the start of the labyrinth with a dead cat!
OK, not trolling here & I hope I delivered a few chuckles; but let's (for the sake of playing chess with ones self...) assume that there is merit in accurately delivering a measurable signal down to DC without shorting the local sub-station. I hope this doesn't start sounding like that review...
How do these subs work? They use a fan (DC) to cause pressurisation (amplification) and vary the frequency by oscillating the pitch of the blades. I won't go into the negative aspects, you can do this yourself by placing your hand in front of an ordinary fan – apart from the noise you'll notice that the air-flow is far from smooth.
How do horns work? They pressurise the air in front of a diaphragm in order to realise a 1:1 theoretical acoustic impedance at the mouth. Diaphragm weighs more than air, but can match the effective weight of pressurised air causing amplification (under oscillation).
I remember my late father once told me about an intriguing PA system that used to be prevalent in the 1930's, way before amplification could sensibly produce anything to upset the neighbours. A small van in the shape of a motor-tricycle would turn up to a venue in order to squawk at visitors: the van was essentially a horn with the mouth opening at the rear. What makes the scenario interesting applies to the greater portion of amplification involved; yes, there was a small maybe <1W amp to move the diaphragm, but relate back to the identical points eluded to in the above two statements: pressurisation = amplification under the right circumstances.
These curious little vans ran a compressor line to the throat of the horn, just in front of the diaphragm. The higher the compression, the louder the horn – simple eh?
So what?
My point is this: rather than rigging up a ludicrously elaborate fan, why not simply pressurise an ordinary driver? You need to pressurise front and rear, and mount in such a way that the rear flow can be terminated/negated – same as the fan. Obviously you need front and rear pressure chambers to enable pressurisation in the same manner as a horn throat, but the pressure delivered by an appropriate airline does the job of the horn mouth – you shouldn't actually need a horn as we know it. And yes – get it right & it'll go down to DC. Further more, you have two modes of amplification: first is your driving amplifier, second is the rate of airflow which provides the required pressure...
All of the above can be achieved at a fraction of the cost of the TR-17, and frankly if you can physically afford the TR-17 along with it's installation, you can do the above. I'll guarantee you'll get <3% distortion 😛 & who knows, maybe it'll play higher than 20Hz...
The_device_is_complex_as_many_devices_that_do_things_in_a_different_way_are.
i_bet_the_first_v4ariable_pitch_propellers_were_dismissed_on_the_same_grounds.
By_design_the_trw_lowers_in_distortion_as_frequency_drops.Its_usable_range_ends_at_40hz_where_cone_based_drivers_excel.
The_article_makes_a_great_point_in_turning_frequency_perception_into_time_perception_to_illustrate_the_fallacy_of_the_20hz_low_frequency_limit.
That_inversion_of_thought_alone_makes_the_article_worth_reading.
Again_if_you_can_find_any_error_to_debunk_the_article_post_them.
I_dont_accept_opinion_as_fact,the_article_is_educational.
Wordy,enthusiastic,boisterous_and_educational.
i_bet_the_first_v4ariable_pitch_propellers_were_dismissed_on_the_same_grounds.
By_design_the_trw_lowers_in_distortion_as_frequency_drops.Its_usable_range_ends_at_40hz_where_cone_based_drivers_excel.
The_article_makes_a_great_point_in_turning_frequency_perception_into_time_perception_to_illustrate_the_fallacy_of_the_20hz_low_frequency_limit.
That_inversion_of_thought_alone_makes_the_article_worth_reading.
Again_if_you_can_find_any_error_to_debunk_the_article_post_them.
I_dont_accept_opinion_as_fact,the_article_is_educational.
Wordy,enthusiastic,boisterous_and_educational.
Hi,
What_is_with_this_utterly_tedious_text_style?
You don't know enough regarding fallacies to
expound on the subject and judge the "experts".
Which PC certainly isn't. Its inanely repetitive
misinformation of the worst sort, self stroking
the ego of someone engaged in self promotion.
rgds, sreten.
What_is_with_this_utterly_tedious_text_style?
You don't know enough regarding fallacies to
expound on the subject and judge the "experts".
Which PC certainly isn't. Its inanely repetitive
misinformation of the worst sort, self stroking
the ego of someone engaged in self promotion.
rgds, sreten.
It doesn't matter how you write it up if it's based in factually inaccurate assumptions.
It's not what it's written up to be, performance is really good in the ULF because of the technology but you can build/buy some impressive stuff for this sort of $$$
Personally I'd be embarrassed if someone wrote up my otherwise good product with such drivel.
It's not what it's written up to be, performance is really good in the ULF because of the technology but you can build/buy some impressive stuff for this sort of $$$
Personally I'd be embarrassed if someone wrote up my otherwise good product with such drivel.
The radiating area is the fixed rotor/blowhole size, the pitch is the variable component, and speed is simply a user setting.
Hi,
I'll guarantee you'll get far more than 3% distortion and
your general arrangement will be awful in all respects.
An airline simply won't deliver the low pressure volume
air flow required. Its similar to single ended via push pull,
and using another fan to produce airflow and then trying
to variably impede it with blades that at no signal are
parallel to the air flow, a pretty naff idea.
Bandwidth of the fan sub depends on rotation speed,
as does maximum output, but self generated noise,
(aka distortion) rapidly becomes a major problem.
(Motor power being synchronous is not a problem.)
3% distortion at 90dB, 1/3W, is probably near the
best compromise of max SPL, bandwidth, distortion.
The levels of distortion at 100W ain't going to be pretty,
but still the fan sub will produce high levels of low bass.
Such levels can be picked up miles away with the right
subsonic encoding equipment and spectral averaging.
However anyone really familiar with the likes of F&M
curves and audible masking will know that a single
fan sub will barely scrape the limits of audibility of low
bass at full power, other than kicking off structural
resonances which are felt rather than heard, or
driving high Q room modes in very big spaces.
rgds, sreten.
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