A good book in german on loudspeakers is Götz Schwamkrug "Lautsprecher - Dichtung und Wahrheit", its from 1986.
PDF download here
http://www.einklang-audio.com/buch/dichtung_und_wahrheit.pdf
Concerning sandwich loudspeakers here some information, page 92 in the book, showing impulse responses in comparison:
small paper cone 4,5 cm, 20cm navi paper cone and 7 cm sandwich cone.
The 7cm sandwich cone has a better impulse response than the smaller 4.5 cm paper cone
Schwamkrugs second book "Lautsprecher Aufbau Nachbau Umbau" is very good, too.
PDF download here
http://www.einklang-audio.com/buch/dichtung_und_wahrheit.pdf
Concerning sandwich loudspeakers here some information, page 92 in the book, showing impulse responses in comparison:
small paper cone 4,5 cm, 20cm navi paper cone and 7 cm sandwich cone.
The 7cm sandwich cone has a better impulse response than the smaller 4.5 cm paper cone
Schwamkrugs second book "Lautsprecher Aufbau Nachbau Umbau" is very good, too.
At the time some years ago where I did measurements I could not find big differences in frequency response.
But waterfall measurements showed cleaned up resonance behavior of alu sandwiched paper cones.
I rarely did distortion measurements.
Some measurements can be found here in the thread. Just look it carefully through.
Usually I treat fullrange drivers with aluminum foil and apply dsp linearization (= auto EQ in the near field with Behringer DEQ2496 or Minidsp plus measurement system). Together you get a real high end loudspeaker because the cone makes the sound.
Additionally:
Either use fullrange drivers with Faraday rings or use transconductance amplifiers to minimize distortions originating from the voice coil and magnet assembly.
So feel free to try out this kind of tweak and make measurements of your own. With your own equipment and loudspeakers. At the end a listening test in A/ B comparison is valuable, too. A report from a second party would be a benefit.
But waterfall measurements showed cleaned up resonance behavior of alu sandwiched paper cones.
I rarely did distortion measurements.
Some measurements can be found here in the thread. Just look it carefully through.
Usually I treat fullrange drivers with aluminum foil and apply dsp linearization (= auto EQ in the near field with Behringer DEQ2496 or Minidsp plus measurement system). Together you get a real high end loudspeaker because the cone makes the sound.
Additionally:
Either use fullrange drivers with Faraday rings or use transconductance amplifiers to minimize distortions originating from the voice coil and magnet assembly.
So feel free to try out this kind of tweak and make measurements of your own. With your own equipment and loudspeakers. At the end a listening test in A/ B comparison is valuable, too. A report from a second party would be a benefit.
One secret of good sound with aluminized paper cones is that in this construction the core is the damping paper. And the foil is mellow household alu not duraluminium and hard polystyrene like DA Barlow used it in the mid sixties.
Or KEF in their famous B139 woofer.
All these break up in hard resonances as they strive for maximized stiffness.
They even never thought about using sandwich construction for fullrange loudspeakers!
For a good impulse response you do need a compromise between all parameters so the sandwich of alu paper alu gives you diaphragms which can have reduced resonances.
If there is left one dominant resonance it can be DSPed out by only linearizing the f response leaving a clean waterfall response.
Or KEF in their famous B139 woofer.
All these break up in hard resonances as they strive for maximized stiffness.
They even never thought about using sandwich construction for fullrange loudspeakers!
For a good impulse response you do need a compromise between all parameters so the sandwich of alu paper alu gives you diaphragms which can have reduced resonances.
If there is left one dominant resonance it can be DSPed out by only linearizing the f response leaving a clean waterfall response.
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Comparison of waterfall measurements.
My measurements of Fane Sovereign 15 300tc with both sides household aluminum foil. Whizzer cones one sided. Small cone with thin alu foil.
https://www.diyaudio.com/community/...loudspeaker-sandwich-cone.402917/post-7468479
First measurement on axis, second off axis
Measurement of the smaller Fane 12 250tc
https://www.diyaudio.com/community/threads/new-15-full-range-fane.308652/post-5419073
https://www.diyaudio.com/community/threads/new-15-full-range-fane.308652/post-5815360
15 300tc
https://www.diyaudio.com/community/threads/new-15-full-range-fane.308652/post-5666663
My measurements of Fane Sovereign 15 300tc with both sides household aluminum foil. Whizzer cones one sided. Small cone with thin alu foil.
https://www.diyaudio.com/community/...loudspeaker-sandwich-cone.402917/post-7468479
First measurement on axis, second off axis
Measurement of the smaller Fane 12 250tc
https://www.diyaudio.com/community/threads/new-15-full-range-fane.308652/post-5419073
https://www.diyaudio.com/community/threads/new-15-full-range-fane.308652/post-5815360
15 300tc
https://www.diyaudio.com/community/threads/new-15-full-range-fane.308652/post-5666663
I have here measurements of a 38cm bass loudspeaker with and without aluminium foil
and with and without added copper rings
(other thread here in DIY Audio Forum I made "How to diy / add a faraday ring to a loudspeaker", but have no access to my old Win XP Laptop with ATB PC measurements system to open the files at the moment.
Downloaded the Demoversion on Kirchner Elektronik de but it cannot open the specific XFT files without Dongle or registration.....
So you have to wait
Although you do not need to trust me (=trust only your own measurements!) - everything I did was measurement assisted and is evidence based.
From the waterfall measurment I did on the 38cm / 15 inch of the aluminized Fane Sovereign you can certainly derive that it looks pretty good for such a big driver up to 2 or 3 Khz. Above this frequency there are the resonances from the dual cone / triple cone construction (whizzer cones).
and with and without added copper rings
(other thread here in DIY Audio Forum I made "How to diy / add a faraday ring to a loudspeaker", but have no access to my old Win XP Laptop with ATB PC measurements system to open the files at the moment.
Downloaded the Demoversion on Kirchner Elektronik de but it cannot open the specific XFT files without Dongle or registration.....
So you have to wait
Although you do not need to trust me (=trust only your own measurements!) - everything I did was measurement assisted and is evidence based.
From the waterfall measurment I did on the 38cm / 15 inch of the aluminized Fane Sovereign you can certainly derive that it looks pretty good for such a big driver up to 2 or 3 Khz. Above this frequency there are the resonances from the dual cone / triple cone construction (whizzer cones).
From post
https://www.diyaudio.com/community/...loudspeaker-sandwich-cone.402917/post-7444206
in this thread here some fotos of a measured aluminium sandwiched fullrange loudspeaker system - you can search a long time to find a 25cm fullrange loudspeaker with such a nice waterfall.
Irrespective how the paper cone looked before putting aluminium on it - the aluminium sandwich foils of thick quality (3x thicker than household alu foil) did not add resonances in the middle tones.
Here you can see a 10 inch driver fullrange going down to 35 Hertz in Reflex, dsp corrected, both sides of the diaphragm is aluminium covered. Dustcap is aluminium hand made. It is not optically perfect but acoustically its o.k.
The ringing in the high frequencies (burst decay) is inaudible so I left the aluminium dust cap untreated.
I is phase linear from approx 200 Hertz to 8 Khz. This is due to the point source - always perfect time response after linearizing the frequency response.
Frequency response of this 10 inch fullrange sandwich driver:
Blue curve on axis
brown curve is 45 degrees off axis
red is bass reflex
There are no tweeters active. It is a fullrange driver.
Burst decay is measured down to -25db
https://www.diyaudio.com/community/...loudspeaker-sandwich-cone.402917/post-7444206
in this thread here some fotos of a measured aluminium sandwiched fullrange loudspeaker system - you can search a long time to find a 25cm fullrange loudspeaker with such a nice waterfall.
Irrespective how the paper cone looked before putting aluminium on it - the aluminium sandwich foils of thick quality (3x thicker than household alu foil) did not add resonances in the middle tones.
Here you can see a 10 inch driver fullrange going down to 35 Hertz in Reflex, dsp corrected, both sides of the diaphragm is aluminium covered. Dustcap is aluminium hand made. It is not optically perfect but acoustically its o.k.
The ringing in the high frequencies (burst decay) is inaudible so I left the aluminium dust cap untreated.
I is phase linear from approx 200 Hertz to 8 Khz. This is due to the point source - always perfect time response after linearizing the frequency response.
Frequency response of this 10 inch fullrange sandwich driver:
Blue curve on axis
brown curve is 45 degrees off axis
red is bass reflex
There are no tweeters active. It is a fullrange driver.
Burst decay is measured down to -25db
From post
https://www.diyaudio.com/community/...loudspeaker-sandwich-cone.402917/post-7444206
in this thread here some fotos of a measured aluminium sandwiched fullrange loudspeaker system with SABA greencones.
Here you find the so much seeked for before / after measurements, so original, one sided and both sides (sandwich) aluminium paper cone with aluminium of very thin quality from the gold smith (several times lighter than household aluminium foil).
You really end up with posting everything several times because people are too lazy to click on links.
https://www.diyaudio.com/community/...loudspeaker-sandwich-cone.402917/post-7444206
in this thread here some fotos of a measured aluminium sandwiched fullrange loudspeaker system with SABA greencones.
Here you find the so much seeked for before / after measurements, so original, one sided and both sides (sandwich) aluminium paper cone with aluminium of very thin quality from the gold smith (several times lighter than household aluminium foil).
You really end up with posting everything several times because people are too lazy to click on links.
Thanks a lot Freedom. No hurry and Im glad you agree that before and after helps us to better judge when the mod pays of mostly. Also to have better basis for suggestions to potential alternative methods/improvements of the procedures.
Also thank you overall for sharing your discoveries.
Cheers!
Also thank you overall for sharing your discoveries.
Cheers!
No hurry or heavy reasons for that Freedom. My suggestion is to post before and after measurements when surcomstances allow it, when you modify in the future. Also to refrain from posting measurements without before. I aknowledge that they are not completely useless, but it would save you from spending time on answering to critzisism like mine 😄.
Its my thoughts on it and best advice I can come up with, but I might not be right. Don't worry, and don't spend too much time going through back-catalog to satisfy my curiosity 😊
Cheers!
Its my thoughts on it and best advice I can come up with, but I might not be right. Don't worry, and don't spend too much time going through back-catalog to satisfy my curiosity 😊
Cheers!
Measurement of Beyma 8 ag/n in marble reflex box with Arta in the near field 15cm with aluminized whizzer with thin foil and the paper cone sandwiched with household alu foil.
There is no measurement of the raw unmodified driver.
Really the Beyma due to a very stiff corrugated paper surround does not do anything below 100 Hertz.
Maybe the driver will get more response after long time break in, who knows.
There is no measurement of the raw unmodified driver.
Really the Beyma due to a very stiff corrugated paper surround does not do anything below 100 Hertz.
Maybe the driver will get more response after long time break in, who knows.
Piezo tweeters with one sided thin alu foil with measurements
https://www.diyaudio.com/community/...best-out-of-cheapo-piezos.409639/post-7658495
https://www.diyaudio.com/community/...best-out-of-cheapo-piezos.409639/post-7658495