Hi tinitus,
No I have not simulated any crossover roll-off.
I keep my crossovers simple and do them by ear from the listening position because simulation cannot tell the whole story.
You say the 77g mms cone can take a little extra weight/coating.
I do not want any cone to be heavier than is necessary for the power/drive it must cope with.
The Eminence Alpha and Beta mms figures are 59g and 60g.
Heavier cones are not as dynamic sounding because more of the electrical waveform energy goes into starting and stopping the cone when it should actually be moving air.
Cheers .......... Graham.
No I have not simulated any crossover roll-off.
I keep my crossovers simple and do them by ear from the listening position because simulation cannot tell the whole story.
You say the 77g mms cone can take a little extra weight/coating.
I do not want any cone to be heavier than is necessary for the power/drive it must cope with.
The Eminence Alpha and Beta mms figures are 59g and 60g.
Heavier cones are not as dynamic sounding because more of the electrical waveform energy goes into starting and stopping the cone when it should actually be moving air.
Cheers .......... Graham.
In fact, with regard to cost, they are much better than you would expect. Those Monacor 130X/8 are really shaking the beliefs. However this combo will not go under 40Hz passive, it will produce as measured. I do think that it would be a very tough contest between my speaker and Martin's Alpha + Fostex, if they were to play side by side.
/Erling
/Erling
Will this one be good enough ? 
http://www.alphardaudio.com/en/product/78/60
Also ,check their 18" woofer .
http://www.alphardaudio.com/en/product/284/61
http://www.alphardaudio.com/en/product/78/60
Also ,check their 18" woofer .
http://www.alphardaudio.com/en/product/284/61
nick mckinney,
On page 1, you posted some FR graphs of the IB15. Do you have graphs with less smoothing? The pdf link on your website seems broken.
In addition, do you have impedance, CSD, nonlinear distortion graphs, etc?
I think we would all like to see them.
I assume your IB15-4 would be similar except for sensitivity and rolloff.
On page 1, you posted some FR graphs of the IB15. Do you have graphs with less smoothing? The pdf link on your website seems broken.
In addition, do you have impedance, CSD, nonlinear distortion graphs, etc?
I think we would all like to see them.
I assume your IB15-4 would be similar except for sensitivity and rolloff.
mbutzkies said:
Its going to be awhile. I myself have been out of the speaker game for a few years and am just now getting back in with John at AE. I have about 4-6 weeks before everything is set up in my shop here and can start doing all the in depth testing. I do have an impedance curve of that same driver though and yes the inductance and phase shift is that low:
An externally hosted image should be here but it was not working when we last tested it.
The bumps you see in the impedance starting at ~575Hz (and the 2 harmonics) are from the spider resonance. This is a linear 30mm p-p xmax driver with about 95dB@1w if memory serves me correctly.
Tinitus or anyone else have you seen/heard these guys.http://www.audiocircle.com/circles/index.php?topic=50353.0
tinitus said:
Hi tinitus,
Mass which is not essential degrades driver cone dynamic capabilities because that moving mass is like a capacitive storage element tuned by its suspension, yet driven via voice coil resistance plus inductance. This is like moving the cone on its own spring via an electro-mechanical spring. Hence Qms, Qes and Qts.
The resonance might be shifted lower and sound deeper, but both efficiency and dynamic capabilities are actually impaired.
(You don't get your mates to climb aboard if you are going to do a 0 to 100 timed run in your car, because they store some energy which would otherwise have allowed the car to attain greater velocity within the same distance and thus greater distance within a given (waveform) time; that extra weight then requires greater braking affort to stop again.)
Music waveforms are not pre-conditioned to provide the additional stop/start energy peaks neccessary for woofer cone mass acceleration and deceleration to maintain a transduced reproduction waveform identical to the original electrical one, so heavier cone drivers with higher inductance voice coils drivers cannot be expected to respond as dynamically as lighter ones;
hence the expression 'slow bass' arising when attempting to augment a wide-range driver with a typical woofer mounted on the same baffle.
Also a driver's dynamic capabilities do not show up on measured or simulated SPL/frequency plots, though we can most certainly hear the difference !
AE drivers have commendably low inductance, though like all other dynamic reproducers still have a voice electro-mechanically in series with their resonant cone assemblies.
Many heavier coned car drivers need to be crossed over at around 100Hz, some around 50Hz, and this is not always wanted when augmenting other drivers on an OB.
Also, when power is provided to shift a heavy cone we need to think about where the drive force originates - the voice coil - via - the driver basket - via - the OB ?
The heavier the cone the greater the equal but opposite forces acting upon and bending/displacing a baffle, though with that common force energising different cone/baffle responses in time.
(One up for the Ripole and bipole, though still not dipole.)
Hi chakija,
The 15" driver you link to is very similar to the Alpha-15A, and is likely to perform similarly on OB.
Cheers ......... Graham.
Graham Maynard said:
I don't agree with this as woofers are constant acceleration devices. If you add mass via a lead ring the frequency response and phase shift stays exactly the same, only the efficiency is changed. The frequency response staying the same shows the cone will move back and forth the same amount relative to all frequencies as before.
IMHO - "slow" woofers are high inductance woofers. Most of the mass of a high inductance (large coil) woofer is in the coil not in the cone. The higher the inductance the greater the phase shift in the driver output.
Qms Qes and Qts are secondary parameters taken from the true electromechanical parameters of the driver. I say they are secondary as they are dependent on the Cms or compliance of the suspension which is variable with temperature and how much the woofer is being worked at that particular moment. I don't read into them very much myself I will admit, I look at the specs that they are derived from instead (motor strength, mass, compliance, Faraday effect of the voice coil former is main effect on Qms)
Graham Maynard said:
I strongly disagree, resonance is required in a direct radiator driver because "flat" response is provided in the "mass-control" region, this is fundamental to loudspeaker design.
from: http://history.sandiego.edu/GEN/recording/loudspeaker.html
1925 - The research paper of Chester W. Rice and Edward W. Kellogg at General Electric was important in establishing the basic principle of the direct-radiator loudspeaker with a small coil-driven mass-controlled diaphragm in a baffle with a broad midfrequency range of uniform response. Edward Wente at Bell Labs had independently discovered this same principle, filed patent No. 1,812,389 Apr. 1, 1925, granted June 30, 1931. The Rice-Kellogg paper also published an amplifier design that was important in boosting the power transmitted to loudspeakers. In 1926, RCA used this design in the Radiola line of a.c. powered radios.
Pete B.
Hi Nick and Pete,
Feel free to disagree: I don't agree with what you have written either.
This especially as I am writing about the dynamic response of a driver, not any 'flat' steady sine response which cannot be measured until all dynamically driven kinectic/potential energy conversions due to mass, loading and resonant development energised by a transducing voice coil have stabilised (normally arising during the time period of a first cycle), for by the time you have a steady response capable of being measured you have already missed the initial dynamic errors.
(The car with extra weight can still go fast but is less responsive to speed/direction change due to its acceleration capabilities being impaired.)
So where does your 'flat' LS response come from - is there a resonant contribution ?
If yes, then where does the resonant energy come from ?
Answer;- It is subtracted from the initial amplitude displacement which develops during the first cycle of waveform. On a dipole this energy storage within a driver arises mostly within the first 90 degrees, but when drivers are mounted in tuned enclosures the storage of energy can take longer (up to a full cycle) and when crossovers are used as well, it can be the second cycle before amplitude responses stabilise.
Nick, if you add mass via a lead ring then the low frequency response (which does include phase shift) cannot fail but to be modified due to driver's Fs being reduced. There might be more resonant 'assistance' with regard to the development of an extended LF response, but the initial dynamic (first 90 degrees) response capabilities will have simultaneously been degraded.
Look at MJKs texts where he illustrates the impulse responses for Alpha, Beta and Gamma drivers. The lower the Qes the more accurate the impulse response capabilities.
Page 11 here;-
http://www.quarter-wave.com/OBs/OB_Design.pdf
Cheers ........... Graham.
Feel free to disagree: I don't agree with what you have written either.
This especially as I am writing about the dynamic response of a driver, not any 'flat' steady sine response which cannot be measured until all dynamically driven kinectic/potential energy conversions due to mass, loading and resonant development energised by a transducing voice coil have stabilised (normally arising during the time period of a first cycle), for by the time you have a steady response capable of being measured you have already missed the initial dynamic errors.
(The car with extra weight can still go fast but is less responsive to speed/direction change due to its acceleration capabilities being impaired.)
So where does your 'flat' LS response come from - is there a resonant contribution ?
If yes, then where does the resonant energy come from ?
Answer;- It is subtracted from the initial amplitude displacement which develops during the first cycle of waveform. On a dipole this energy storage within a driver arises mostly within the first 90 degrees, but when drivers are mounted in tuned enclosures the storage of energy can take longer (up to a full cycle) and when crossovers are used as well, it can be the second cycle before amplitude responses stabilise.
Nick, if you add mass via a lead ring then the low frequency response (which does include phase shift) cannot fail but to be modified due to driver's Fs being reduced. There might be more resonant 'assistance' with regard to the development of an extended LF response, but the initial dynamic (first 90 degrees) response capabilities will have simultaneously been degraded.
Look at MJKs texts where he illustrates the impulse responses for Alpha, Beta and Gamma drivers. The lower the Qes the more accurate the impulse response capabilities.
Page 11 here;-
http://www.quarter-wave.com/OBs/OB_Design.pdf
Cheers ........... Graham.
Nick,
It looks like you have impedance blips at 60 hz and 180hz as well. What are they from? Do they show up in unsmoothed FR or CSD graphs?
If the spider of the IB15 is producing the resonance at 575hz, would the dipole15 have its spider at an even lower resonance because it has a much larger VAS?
It seems the impedence peak is pretty large, do you recommend an impedence notch filter at Fs?
It looks like you have impedance blips at 60 hz and 180hz as well. What are they from? Do they show up in unsmoothed FR or CSD graphs?
If the spider of the IB15 is producing the resonance at 575hz, would the dipole15 have its spider at an even lower resonance because it has a much larger VAS?
It seems the impedence peak is pretty large, do you recommend an impedence notch filter at Fs?
Graham Maynard said:
Of course the LF is changed as that is where the resonance with the system suspension is happening. What I was trying to show that the HF response stays exactly the same in both phase and frequency output.
I like Pete cannot convince you as what you are saying is said by every non speaker engineer in the speaker world and it is near impossible to get people to understand it as it seems opposite of what it should be. Play around modifying some raw drivers and see for yourself.
The Alpha 15 and the IB 15 are two different animals.
A direct radiator loudspeaker, in either an OB or acoustic suspension (AS) enclosure is a high pass filter where the characteristic frequency is determined by Fs for OB and Fc for AS.
This characteristic frequency sets the position of the high pass filter and therefore it should be chosen based on the expected program content and price point. Price factors in because the lower in frequency the design target, the larger the required volume displacement (VD) and thus more or better drivers are needed.
Interesting, the Alpha 15 has an Fs of 41 Hz. 41 Hz is E1 the lowest note on a 4 string bass, good for the majority of rock, jazz, and pop music at least before the 5 string basses became popular. Also interesting that the classic AR1 family and Large Advent were also tuned with an Fc in the low 40s. However there is obviously more, A0 is the lowest note on a grand piano at 27.5 Hz, and the well known C0 at 16.35 Hz for large pipe organs (32' pipe). John and Nick's design is more of an ultimate solution with a low Fs of 16 Hz, longer Xmax, and copper shorting ring to support the increase in required VD.
http://www.contrabass.com/pages/frequency.html
I view the Alpha 15 as an excellent economy solution and the IB 15 as an ultimate design. A driver with a 20-25 Hz Fs would make sense for those who want more output but do not need extension to 16 Hz.
Pete B.
A direct radiator loudspeaker, in either an OB or acoustic suspension (AS) enclosure is a high pass filter where the characteristic frequency is determined by Fs for OB and Fc for AS.
This characteristic frequency sets the position of the high pass filter and therefore it should be chosen based on the expected program content and price point. Price factors in because the lower in frequency the design target, the larger the required volume displacement (VD) and thus more or better drivers are needed.
Interesting, the Alpha 15 has an Fs of 41 Hz. 41 Hz is E1 the lowest note on a 4 string bass, good for the majority of rock, jazz, and pop music at least before the 5 string basses became popular. Also interesting that the classic AR1 family and Large Advent were also tuned with an Fc in the low 40s. However there is obviously more, A0 is the lowest note on a grand piano at 27.5 Hz, and the well known C0 at 16.35 Hz for large pipe organs (32' pipe). John and Nick's design is more of an ultimate solution with a low Fs of 16 Hz, longer Xmax, and copper shorting ring to support the increase in required VD.
http://www.contrabass.com/pages/frequency.html
I view the Alpha 15 as an excellent economy solution and the IB 15 as an ultimate design. A driver with a 20-25 Hz Fs would make sense for those who want more output but do not need extension to 16 Hz.
Pete B.
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