Hello to all ,
I have a pair of these loudspeakers on my system , and I am questioning about these fake corrugations . I an saying fake because the backside of the cone is totally smooth . So there is some extra thikness from place to place , on the front side of the cone .
Anyone knows the purpose of that extra thickness ?
For me , it seems useless . I'm thinking in sanding the conehttps://files.diyaudio.com/forums/images/icons/icon7.gif
Thank's in advance .
I have a pair of these loudspeakers on my system , and I am questioning about these fake corrugations . I an saying fake because the backside of the cone is totally smooth . So there is some extra thikness from place to place , on the front side of the cone .
Anyone knows the purpose of that extra thickness ?
For me , it seems useless . I'm thinking in sanding the conehttps://files.diyaudio.com/forums/images/icons/icon7.gif
Thank's in advance .
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Hello
I assume the corrugations on the frontside are the concentric rings (as viewed on the datasheet for 15K200).
I am pretty sure they are there for obtaining a controlled breakup up of the membrane - effectively creating a mechanical lowpass filtering of the outer sections on the membrane.
Sanding them down would likely result in a very less controlled breakup above - say (guessing) - 500 Hz.
Unless you aim for a speaker with strong unlinearity I would not remove the rings.
Cheers, Martin
I assume the corrugations on the frontside are the concentric rings (as viewed on the datasheet for 15K200).
I am pretty sure they are there for obtaining a controlled breakup up of the membrane - effectively creating a mechanical lowpass filtering of the outer sections on the membrane.
Sanding them down would likely result in a very less controlled breakup above - say (guessing) - 500 Hz.
Unless you aim for a speaker with strong unlinearity I would not remove the rings.
Cheers, Martin
With due respect, you lack experience in speaker design, specially parts used in them.
The wave traveling from voice coil to edge and back only knows of mass and elasticity along the way, thinner part of cone has both, of course, and any "ridge" in the way adds extra mass *there*, which causes a discontinuity, partly "breaking the wave", partly crating a mechanical lowpass as mentioned above, imagine a ball of metal at the end of a steel bar, and causing a localized breakdown.
One way to break up cone vibration in a controlled way is to add a concave/convex ridge as you mention; another is to add an extra mass ring, both work fine.
When turning a cone mold in a lathe, it´s MUCH easier to just cut a groove in one of them (generally the front one) than trying to remove material from the back half leaving just the matching ridge, and that guaranteeing exact same position and keeping constant thickness, so these are far less popular.
The wave traveling from voice coil to edge and back only knows of mass and elasticity along the way, thinner part of cone has both, of course, and any "ridge" in the way adds extra mass *there*, which causes a discontinuity, partly "breaking the wave", partly crating a mechanical lowpass as mentioned above, imagine a ball of metal at the end of a steel bar, and causing a localized breakdown.
One way to break up cone vibration in a controlled way is to add a concave/convex ridge as you mention; another is to add an extra mass ring, both work fine.
When turning a cone mold in a lathe, it´s MUCH easier to just cut a groove in one of them (generally the front one) than trying to remove material from the back half leaving just the matching ridge, and that guaranteeing exact same position and keeping constant thickness, so these are far less popular.
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Thank's Guys !
Meantime , I have also a pair of PR 380T4 Audax without corrugations , and I prefer the sound ot these ones , I find the sound a lot more lively , as these Beyma sounds dull IMO . Both have same moving coil diameter , same magnet diameter
As I live in apartment , I'm listening at low levels , where the energy reflected issue seems less critical
Meantime , I have also a pair of PR 380T4 Audax without corrugations , and I prefer the sound ot these ones , I find the sound a lot more lively , as these Beyma sounds dull IMO . Both have same moving coil diameter , same magnet diameter
As I live in apartment , I'm listening at low levels , where the energy reflected issue seems less critical
'Lively' in driver design parlance = break-up modes/distortion, no matter how euphonic it sounds. 🙁
GM , thanks for sharing your opinion . At the moment I am most concerned by the quality of transient response , altough it could be a dead end .
You're welcome!
Then you're most interested in the driver's summed response below its upper mass corner [Fhm = 2*Fs/Qts'] combined with a flat amplitude and phase response above it, so at best, basically limited to its pistonic BW which ends at the driver's VC diameter in Hz, so power handling requirements will dictate its usable HF response.
[Qts']: [Qts] + any added series resistance [Rs]: Calculate new Qts with Series Resistor
[Rs] = 0.5 ohm minimum for wiring, so may be higher if a super small gauge is used as a series resistor plus any added resistance from an XO/whatever.
FWIW, maybe as sort of a frame of reference; this was my choice back in the mid 60's XO'd 500 Hz/2nd: http://www.lansingheritage.org/images/altec/specs/components/515b/page02.jpg
This was for a low power matching impedance tube amp [DF = 1] with mine measuring ~20 Hz Fs, 0.2 Qts, 20 ft^3 Vas, so today would look for similar except with a ~0.312 Qts since amps today have vanishing low output impedance [super high DF] and if needing a smaller box, then would choose based on the pioneer's Vb = Vas/1.44.
Then you're most interested in the driver's summed response below its upper mass corner [Fhm = 2*Fs/Qts'] combined with a flat amplitude and phase response above it, so at best, basically limited to its pistonic BW which ends at the driver's VC diameter in Hz, so power handling requirements will dictate its usable HF response.
[Qts']: [Qts] + any added series resistance [Rs]: Calculate new Qts with Series Resistor
[Rs] = 0.5 ohm minimum for wiring, so may be higher if a super small gauge is used as a series resistor plus any added resistance from an XO/whatever.
FWIW, maybe as sort of a frame of reference; this was my choice back in the mid 60's XO'd 500 Hz/2nd: http://www.lansingheritage.org/images/altec/specs/components/515b/page02.jpg
This was for a low power matching impedance tube amp [DF = 1] with mine measuring ~20 Hz Fs, 0.2 Qts, 20 ft^3 Vas, so today would look for similar except with a ~0.312 Qts since amps today have vanishing low output impedance [super high DF] and if needing a smaller box, then would choose based on the pioneer's Vb = Vas/1.44.
Don’t go and ruin a perfectly good pair of 15K200.
Your ears deceive you. And without good measurements you are not able to deduct the cause of what you hear. Generally a good driver has to sound dull, if it sounds bright by itself it obviously hasn’t been designed that well.
Your ears deceive you. And without good measurements you are not able to deduct the cause of what you hear. Generally a good driver has to sound dull, if it sounds bright by itself it obviously hasn’t been designed that well.
Hello to all ,
Gm , I'm listening at the moment with a SE 6B4G .
Markbakk &Justanalog :I finally partially sanded the five corrugations close to the moving coil . The tonal balance is almost the same , a bit of medium and treble added , despite of filter 600 Hz/3rd .I'm not supposed to take a loudspeaker "as is " , you need only look under a dust cap to see some cost trade-off , or quality control issues .
Gm , I'm listening at the moment with a SE 6B4G .
Markbakk &Justanalog :I finally partially sanded the five corrugations close to the moving coil . The tonal balance is almost the same , a bit of medium and treble added , despite of filter 600 Hz/3rd .I'm not supposed to take a loudspeaker "as is " , you need only look under a dust cap to see some cost trade-off , or quality control issues .
Hello to all ,
Gm , I'm listening at the moment with a SE 6B4G .
Markbakk &Justanalog :I finally partially sanded the five corrugations close to the moving coil . The tonal balance is almost the same , a bit of medium and treble added , despite of filter 600 Hz/3rd .
I'm not supposed to take a loudspeaker "as is " , you need only look under a dust cap to see some cost trade-off , or quality control issues .
Gm , I'm listening at the moment with a SE 6B4G .
Markbakk &Justanalog :I finally partially sanded the five corrugations close to the moving coil . The tonal balance is almost the same , a bit of medium and treble added , despite of filter 600 Hz/3rd .
I'm not supposed to take a loudspeaker "as is " , you need only look under a dust cap to see some cost trade-off , or quality control issues .
I struggle understanding the meaning of transients with regards to bass drivers.
I know what they are with regards to bass sounds though. For example in kick drum sound the transients are what gives the sound 'attack', they are the high frequency components at around 2-4kHz of the sound.
Transient is a quick or sudden change.
And the speakers ability to reproduce such a transient
Such as a sudden change in pitch, or sudden change in sound pressure.
or sudden change in the sustain or speed of notes, percussion etc etc
electronic music can have incredible ranges of bass tones, and drum tones
and the pitch, volume , sustain and timing can change rather rapidly.
And the speakers ability to reproduce such a transient
Such as a sudden change in pitch, or sudden change in sound pressure.
or sudden change in the sustain or speed of notes, percussion etc etc
electronic music can have incredible ranges of bass tones, and drum tones
and the pitch, volume , sustain and timing can change rather rapidly.
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Just means it's accurately following the signal and in the case of a woofer it's by definition very slow unless it's a very wide BW woofer XO'd quite high such as the Altec/GPA 515 woofer based 604 duplex XO'd at 1600 Hz with of course the leading edge of the transient being reproduced by the HF horn since the lower the fundamental, the wider its [transient] BW.
I think we are generally in agreement then GM that rapid changes are largely HF issues.
The Altec is a bit of an outlier in the modern world with the 1.6k crossover.
Tannoy crossed their 15" at about half that.
The Altec is a bit of an outlier in the modern world with the 1.6k crossover.
Tannoy crossed their 15" at about half that.