They will produce much cleaner, low distortion and higher definition 135dB bass than any Hi-Fi speaker 
Would you argue on this?
There is absolutely nothing wrong with 3dB p-p of bass horn ripple. A lot of PA mids and tweeters are worse. The trick is to correct phase in the crossover region for good on-axis summing and no lobing.
Hey! With small Hi-Fi direct radiators you usually have 20dB p-p of room-modes bass ripple and people does not complain...
Would you argue on this?There is absolutely nothing wrong with 3dB p-p of bass horn ripple. A lot of PA mids and tweeters are worse. The trick is to correct phase in the crossover region for good on-axis summing and no lobing.
Hey! With small Hi-Fi direct radiators you usually have 20dB p-p of room-modes bass ripple and people does not complain...
Reasonably sized bass horns don't always provide the best linear distortion stats.
But horn loading can dramatically improve non-linear distortion. I've never heard any of Eva's work, but based on her technical know-how, I would trust that anything she designs would sound great in it's intended use.
But horn loading can dramatically improve non-linear distortion. I've never heard any of Eva's work, but based on her technical know-how, I would trust that anything she designs would sound great in it's intended use.
Hi TOINO
The ripple is the price that you have to pay for well controlled cone excursion down to 40Hz in a horn smaller than a fridge It's nothing that you can't flatten with a DSP.
This is a cone excursion plot at 1200W. SPL at this power is 142dB (one quarter space). The driver is rated at +/-8mm Xmax and 600W rms. Given the high and reactive electrical impedance resulting from horn loading, I expect it to actually handle 1200W program power. Try to do this with a reflex box
I designed my previous folded bass horn prototype fearing bad response at midbass frequencies. As a result it had only two 90 degree bends and I got a lot of output up to 600Hz, but the lowest resonant mode was at 75Hz and it was lacking a lot of output and cone displacement control below 64Hz (this was actually fine in a small room). This new one will have two 90 degree bends too but will be taller to accomodate the longer expansion.
The ripple is the price that you have to pay for well controlled cone excursion down to 40Hz in a horn smaller than a fridge
It's nothing that you can't flatten with a DSP.This is a cone excursion plot at 1200W. SPL at this power is 142dB (one quarter space). The driver is rated at +/-8mm Xmax and 600W rms. Given the high and reactive electrical impedance resulting from horn loading, I expect it to actually handle 1200W program power. Try to do this with a reflex box
I designed my previous folded bass horn prototype fearing bad response at midbass frequencies. As a result it had only two 90 degree bends and I got a lot of output up to 600Hz, but the lowest resonant mode was at 75Hz and it was lacking a lot of output and cone displacement control below 64Hz (this was actually fine in a small room). This new one will have two 90 degree bends too but will be taller to accomodate the longer expansion.
Hi Princess
So you have constructed it!... I see that you really don’t care your nails.
Well… I am very inflexible with the ripple stuff; I am a “straight” kind of weird.
With a fridge size and the correct loudspeaker/front-chamber/rear-chamber+resonator it is possible to do it without ripple.
Anyway if you measure the impedance in diverse environments and positions, you will discover that the ripple changes.
Because of that I am apprehensive with your linearity correction proposal. That way you must tweak the processor to sync the ripple every time you move the horn.
Also your proposal is dangerous for cone integrity… take a closer look to the peak-excursion//ripple-valley coincidence.
I have a much better idea:
What if you construct two horns? One with the ripple-valleys sync with ripple-peaks of other?
Nahh! For that size and target pressure/bandwidth I prefer to spend more amplifier power.
P.S. Don’t forget the brick-wall hi-pass filter. You need at least 48dB/oct to keep the cone and the roof in one piece.
So you have constructed it!... I see that you really don’t care your nails.
Well… I am very inflexible with the ripple stuff; I am a “straight” kind of weird.
With a fridge size and the correct loudspeaker/front-chamber/rear-chamber+resonator it is possible to do it without ripple.
Anyway if you measure the impedance in diverse environments and positions, you will discover that the ripple changes.
Because of that I am apprehensive with your linearity correction proposal. That way you must tweak the processor to sync the ripple every time you move the horn.
Also your proposal is dangerous for cone integrity… take a closer look to the peak-excursion//ripple-valley coincidence.
I have a much better idea:
What if you construct two horns? One with the ripple-valleys sync with ripple-peaks of other?
Nahh! For that size and target pressure/bandwidth I prefer to spend more amplifier power.
P.S. Don’t forget the brick-wall hi-pass filter. You need at least 48dB/oct to keep the cone and the roof in one piece.
Ripple rotates phase, so actually two horns with different ripple are over 90 degrees out of phase most of the time and tend to cancel rather than summing (actually it only cancels on-axis, but it makes good lobes off-axis... Closed venues, anyone? ) Have you ever worked with a PA system having mixed bass horn models? It is really frustrating when you try to EQ it.
On the other hand, I know that ripple changes depending on the environment and I'm quite good when it comes to move the parametric EQs to correct it in the crossover region by ear. Anyway, don't you always start with a flat EQ in each new venue?
Cone excursion after EQ is not really a big problem unless you play 60Hz tones (like plugging the speaker to US mains?) because music power spectrum is nicely spread among the passband. Similarly, the brickwall filter is only required if you plan to play full power 30Hz tones (and I don't feel like doing that).
Most of the ripple disappears by placing 4 horns together (or two with a wall behind, which is what I expect to do most of the time). There is no way to get rid of the ripple unless you either shorten the horn, which moves the lowest resonance upwards or you enlarge the mouth, which results in non-practical size.
PA companies like to tell wonderful tales about diminute high performance bass horns and ultra compact bass systems... Most of them actually measure terrible Better not to speak about bass in line arrays 
People is definitely happy with anything expensive, well advertised and with a well known company name behind (performance? what is this?)
) Have you ever worked with a PA system having mixed bass horn models? It is really frustrating when you try to EQ it.On the other hand, I know that ripple changes depending on the environment and I'm quite good when it comes to move the parametric EQs to correct it in the crossover region by ear. Anyway, don't you always start with a flat EQ in each new venue?
Cone excursion after EQ is not really a big problem unless you play 60Hz tones (like plugging the speaker to US mains?) because music power spectrum is nicely spread among the passband. Similarly, the brickwall filter is only required if you plan to play full power 30Hz tones (and I don't feel like doing that).
Most of the ripple disappears by placing 4 horns together (or two with a wall behind, which is what I expect to do most of the time). There is no way to get rid of the ripple unless you either shorten the horn, which moves the lowest resonance upwards or you enlarge the mouth, which results in non-practical size.
PA companies like to tell wonderful tales about diminute high performance bass horns and ultra compact bass systems... Most of them actually measure terrible
Better not to speak about bass in line arrays People is definitely happy with anything expensive, well advertised and with a well known company name behind (performance? what is this?)
Also important is to not mix different power amplifiers even if the cabinets are all equal.
Their almost certainly different hi-pass filters introduce phase variations that result in unpredictable directional patterns and other phenomena.
Most Line-Arrays in the market are real bull s** t (amplifiers in the same bag) but they are exceptions…
The problem with those commercial products and producers is that “any fool could know, the point is to understand”…
Competent Line-(source) array stuff is very good solution and you must try a good one to change your mind.
With a good one, you start with flat-eq and you finish more or less on the same way.
P.S.
Of course I play full power 30Hz tones!
Now you think that no such signal exists on a typical band…
And you are right! http://www.dbxpro.com/120A/120A.php
Imagine the size of individual boxes if I use classical horn cabinets…
Their almost certainly different hi-pass filters introduce phase variations that result in unpredictable directional patterns and other phenomena.
Most Line-Arrays in the market are real bull s** t (amplifiers in the same bag) but they are exceptions…
The problem with those commercial products and producers is that “any fool could know, the point is to understand”…
Competent Line-(source) array stuff is very good solution and you must try a good one to change your mind.
With a good one, you start with flat-eq and you finish more or less on the same way.
P.S.
Of course I play full power 30Hz tones!
Now you think that no such signal exists on a typical band…
And you are right! http://www.dbxpro.com/120A/120A.php
Imagine the size of individual boxes if I use classical horn cabinets…
I came across a specific type of primary winding in smps transformer of this amp.
Primary is sandwitched between 2 halfs of secondary.
Primary also features and EXTRA UNCONNECTED EXTENDED TURNS which covers the whole bobbin as if used for some kind of screening.Transformer is switched at 115KHZ quasi-resonant.
Does anybody knows about the extra unconnected turns effect of primary. Primary Turn count is 10Turns + 1 extra unconnected turn.
Primary is sandwitched between 2 halfs of secondary.
Primary also features and EXTRA UNCONNECTED EXTENDED TURNS which covers the whole bobbin as if used for some kind of screening.Transformer is switched at 115KHZ quasi-resonant.
Does anybody knows about the extra unconnected turns effect of primary. Primary Turn count is 10Turns + 1 extra unconnected turn.
Hmm… on your image here http://www.diyaudio.com/forums/showthread.php?postid=1400804#post1400804 it is not visible any resonator coil…
As you say that it is quasi-resonant and they are no coil then probably the transfo has deliberately hi leakage inductance to resonate with the two visible green tubular caps near to transfo?...
What’s that nucleus size anyway?
It seems EE47 for me… Bet you that is half-bridge…!
Woau! EE47 // 115KHz – 8KW !!! Miracle or Witchcraft???
Hey Workhorse… you could be arrested by reverse-engineer.
As you say that it is quasi-resonant and they are no coil then probably the transfo has deliberately hi leakage inductance to resonate with the two visible green tubular caps near to transfo?...
What’s that nucleus size anyway?
It seems EE47 for me… Bet you that is half-bridge…!
Woau! EE47 // 115KHz – 8KW !!! Miracle or Witchcraft???
Hey Workhorse… you could be arrested by reverse-engineer.
Hi Toino,
The resonance is achieved through leakage inductance which in this case is around 5.5uH. The caps are 2 X 0.47uF 400V Vishay.
The Ferrite core is EPCOS 3F3 EE55. Operation is halfbridge.
Hey,I donot reverse engineer, what I do is analysis, so i am analyst in nature, therefore no arrests.
The resonance is achieved through leakage inductance which in this case is around 5.5uH. The caps are 2 X 0.47uF 400V Vishay.
The Ferrite core is EPCOS 3F3 EE55. Operation is halfbridge.
Hey,I donot reverse engineer, what I do is analysis, so i am analyst in nature, therefore no arrests.
Eva said:This is a cone excursion plot at 1200W. SPL at this power is 142dB (one quarter space). The driver is rated at +/-8mm Xmax and 600W rms. Given the high and reactive electrical impedance resulting from horn loading, I expect it to actually handle 1200W program power. Try to do this with a reflex box
[/B]
I see you have gone to the Dark side. Danley sent me there about 5 years ago. It started with just two boxes, and then the project took on a life of its own.
Get a 120A, then that will give you the motivation to build the other two (four, six) boxes
What driver you using, the Kappa P15LF2?
TOINO said:
Woau! EE47 // 115KHz – 8KW !!! Miracle or Witchcraft???
Hey Workhorse… you could be arrested by reverse-engineer.
Reverse engineering? Isn't that how you learn to build things? Who *hasn't* taken things apart to see how they work, starting about 6 or 7 years old....
About the 8kW trafo witchcraft - that's 8 (perhaps 10) kW at 12.5% duty factor.
Output devices
The idea of using just 2 500V ISOTOP switches in a half-bridge running from about +/-200V looks attractive at first glance, but I'm wondering what output devices QSC are using?
Assuming they're from APT (I bet they are given where QSC are based) they could be using either the ISOTOP PowerMOS7 FREDFETs (like APT51F50J) or IGBTs with fast antiparallel diode (like APT30GP60JDQ1).
The FREDFETs have lousy Trr/Qrr body diodes (Trr>300ns even at 25C, almost double this at 125C) ) which would lead to enormous switching losses during turn-on.
The IGBTs have much faster diodes (separate chip in same package) but the IGBT current fall time during switching is long (>100ns) which would lead to enormous switching losses during turn-off...
Am I missing something, or do they have enormous switching losses?
Ian
The idea of using just 2 500V ISOTOP switches in a half-bridge running from about +/-200V looks attractive at first glance, but I'm wondering what output devices QSC are using?
Assuming they're from APT (I bet they are given where QSC are based) they could be using either the ISOTOP PowerMOS7 FREDFETs (like APT51F50J) or IGBTs with fast antiparallel diode (like APT30GP60JDQ1).
The FREDFETs have lousy Trr/Qrr body diodes (Trr>300ns even at 25C, almost double this at 125C) ) which would lead to enormous switching losses during turn-on.
The IGBTs have much faster diodes (separate chip in same package) but the IGBT current fall time during switching is long (>100ns) which would lead to enormous switching losses during turn-off...
Am I missing something, or do they have enormous switching losses?
Ian
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