I Just Ordered 12 Faital Pro 3FE25 Speakers |
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70,s hero
Young Croc Joined: 14 December 2014 Location: bristol Status: Offline Points: 637 |
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Yes I can see that this works, how does the amplifier see the le as frequency increase, just was thinking as the amp sees the r rise, does that effect it?
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Top banana
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Elliot Thompson
Old Croc Joined: 02 April 2004 Location: United States Status: Offline Points: 5172 |
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The impedance will rise as the driver approaches its Le. The degree of the rise will vary pending on the model number of the loudspeaker. It appears the Le does not react like the fs in which, the resistance will peak at its resonant frequency and decline. The Le will continue to rise. It may peak at some point and decline but that is well beyond 20 kHz. I never pursued how high of a rise in resistance some speakers offer at high frequencies. Although, I have measured speakers in which the Le offered a resistance at the given frequency beyond 100 ohms. Best Regards, Edited by Elliot Thompson - 04 March 2015 at 5:57pm |
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Elliot Thompson
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70,s hero
Young Croc Joined: 14 December 2014 Location: bristol Status: Offline Points: 637 |
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So the Le is really just an example of electrical resistance at a given frequency in effect that changes with voltage gain, so at higher frequencies resistance increases where the modulation of the voice coil and back EMF increase producing limiting effects.? (LPF)
The FS peak at resonant frequency is due to the free movement (suspension no longer acting on the system) allowing the coil to move more freely and so the amp drives the coil more efficiently within the field again producing more back EMF? The L.E. continues to rise with frequency as the EMF created by the voice coil within the field is increasing with frequency.I think this is correct? |
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Top banana
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Elliot Thompson
Old Croc Joined: 02 April 2004 Location: United States Status: Offline Points: 5172 |
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Yes. That is the characteristics of all loudspeakers. The resonant frequency will shift downwards once the loudspeaker is placed in a cabinet or a means of added mass. It is this type of phenomenon which constitutes the VAS. A Manufacture will measure a driver's TS Parameters in free and post the results publically. The parameters will always change once you mount a non-closed-back driver in an enclosure. This is why I measure the impedance response curve in the enclosure as it is the true response on how the loudspeaker is reacting in the enclosure. Nevertheless, the loudspeakers arrived so my measurements will commence. I will post graphs of my results shortly. Best Regards, Edited by Elliot Thompson - 04 March 2015 at 11:54pm |
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Elliot Thompson
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70,s hero
Young Croc Joined: 14 December 2014 Location: bristol Status: Offline Points: 637 |
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Thanks Elliott, this all makes some sense now in relation to how a driver reacts in free air and within a cabinet.... in certain circumstances. As a matter of interest would there be any advantage in decoupling (directly) the load of the amplifier from the voice coil (if say I could do that). I see that Hi Fi enthusiasts prefer valve type output stages due to there being no effective damping factor. I think I understand that the damping is the value referenced that gives an indication of how much the amplifier is able to control the voice coil when it is in a 0 ve state? I appreciate your input and I can see that you have taken the approach where your designed systems have and are limited to a certain voltage gain which provides for a much lower amount of distortion when compared to most P.A. applications.
Edited by 70,s hero - 05 March 2015 at 9:40am |
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Top banana
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70,s hero
Young Croc Joined: 14 December 2014 Location: bristol Status: Offline Points: 637 |
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Oh and I almost forgot, enjoy your new speakers... I look forward to seeing and tying to understand the data.
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Top banana
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kevinmcdonough
Old Croc Joined: 27 June 2005 Location: Glasgow Status: Offline Points: 3749 |
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hey
also been looking at this kind of design, tall thin columns go down very well in weddings and other work (especially in white). Was wondering though, are you guys thinking sealed or vented boxes? Doing a few quick sims on a column of 16, you can keep it pretty small if its a sealed box, get ruler flat down to 200Hz then a gentle roll off, can probably cross maybe 150 or so. Or as always, with a ported box you get down a good bit lower but excursion goes up and it has to be a surprisingly big box box not to have a big lump in the response at the low end before the drop off. k |
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Elliot Thompson
Old Croc Joined: 02 April 2004 Location: United States Status: Offline Points: 5172 |
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Here are the graphs as promised. Please note the majority of work I have done with these speakers were measuring.
1 kHz – 20,000 kHz Comparison dB Response
500 Hz – 10,000 kHz Comparison Magnitude Low Levels
https://www.youtube.com/watch?v=HcDmWsaabxg&feature=youtu.be
T.H.D. Comparisons Low Levels
T.H.D. Faital Pro 3FE 25
Measured Impedance Faital Pro 3FE 25
https://www.youtube.com/watch?v=mzy-FzJy9N0&feature=youtu.be
Measured Phase Faital Pro 3FE 25
As I only have a few strips of spare wood available, I can only build a sealed cabinet that can house 4 out of 12 Faital Pro 3FE 25 loudspeakers at the moment.
Upon viewing the Faital Pro 3FE 25, you will notice the magnet is around 2 ¾ of inch in diameter. The magnetic field is very strong to the point the magnet will attract anything near it. Placing two Faital Pro 3Fe 25 loudspeakers side to side will literally push the one you do not have your hands on away on a flat surface. When I witness this behaviour, I was pleasantly reminded of what happens when you try to place two magnets together in school at 6 years of age.
Surely, Faital Pro could have offered rubber housing on the magnets to prevent such repels once having two or more drivers close together. Fortunately, the cardboard carton is thick enough to create a shielding cup with a dab of Gorilla tape over the magnets. Of course, some would not bother. However upon playing music through 6 Faital Pro 3FE 25’s I noticed a lot phase issues which may have attribute to the magnets trying to repel from one another that did not coexist once I shielded the magnets.
The sound quality of these speakers offers a resemblance of a tweeter. The first thing you will notice using one Faital Pro 3FE 25 in free air is a lot of sibilance. This may be a good or bad thing pending on the music you are reinforcing. I would generally boost 10 kHz and above for compression drivers. For no matter what the manufacture claims, compression drivers always begin to decline around 9 kHz. With the Faital Pro 3FE 25, you will find such boosting is no longer needed.
Pay attention to the impedance curve from 10 kHz – 20 kHz photo in addition to the video. You will see the resistance is below 11 ohms.
The frequency response is exactly what I was
aiming for within the mid-high frequency region. The response is smooth enough
to dampen the jagged response of the compression driver. Bear in mind the resolution
is 32768 which equates to a hop every 2.93 Hz. Take into consideration that the test signal is a
9 second sine wave sweep, the consistency is very good considering the
measurement ranges from 1 kHz – 20, 000 kHz.
I will post more findings once I build a box for these speakers.
Best Regards, Edited by Elliot Thompson - 05 March 2015 at 12:12pm |
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Elliot Thompson
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Elliot Thompson
Old Croc Joined: 02 April 2004 Location: United States Status: Offline Points: 5172 |
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I made a temporary box to house 5 Faital Pro 3FE 25 loudspeakers and, merged them with 4 Eminence Beta 10 CBMRA Midrange speakers. The HPF is 100 Hz, 12 dB per octave with the microphone 3.04 metres on axis.
The video below offers such an ensemble
playing Jazz Vocals. https://www.youtube.com/watch?v=dfRvRxTiHlw&feature=youtu.be Best Regards, Edited by Elliot Thompson - 06 March 2015 at 1:29am |
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Elliot Thompson
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bzhm
Registered User Joined: 30 June 2014 Status: Offline Points: 10 |
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Hi Elliott,
Unfortunately your plots are no longer available, I would be very interested if you can repost it. Thanks a lot,
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Elliot Thompson
Old Croc Joined: 02 April 2004 Location: United States Status: Offline Points: 5172 |
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Every week I am measuring some audio related device. Finding such graphs I created 5 years ago, would be easily found accidentally than on purpose.
Here is something recent...
The Phase/Impedance plot below illustrates 5 Faital Pro 3FE25 loudspeakers in a sealed enclosure with 5 years of service.
Note: The loudspeakers have been driven by a Peavey PV 2600 (1207.56 watts per channel @ 4 ohms Benched Tested) throughout the 5 year period from 1.5 kHz on up.
The loudspeakers are out-of-phase by -2.0 degrees @ 1498.90 kHz (5.5 ohms) and are in-phase from 2485.11 kHz on up. Impedance fluctuates from 5.50 ohms to 5.77 ohms within the 1.5 kHz - 20 kHz range. The upper frequency usable range does not go beyond 26 kHz.
Based on the impedance curve of 5 Faital Pro 3FE25 in a sealed enclosure, the available power fed to the loudspeakers from the Peavey PV 2600 is 878.83 watts (5.5 ohms) - 836.86 watts (5.77 ohms) per channel within a 1.5 kHz - 20 kHz range.
The measured Le of a single Faital Pro 3FE25 is 0.0272 MH The calculated Le of five Faital Pro 3FE25 is 0.00544 MH
Best Regards,
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Elliot Thompson
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