Joachim,
I propose that what you have done by coating the cone with a lacquer if it does not penetrate the paper from front to back has added a secondary layer that has a different transfer function than the paper itself. Therefor you have two separate wavefronts traveling simultaneously in the composite and this will smear or in effect change the distribution of sound over a limited range but these two waves would add and subtract from the total output. This very much goes along with my thinking in the cone material that I have developed that uses more than one type of composite material and the matrix resin. Not something that is easy to analyze, but intuitively you can see that different materials have different transmission speeds of sound.
I propose that what you have done by coating the cone with a lacquer if it does not penetrate the paper from front to back has added a secondary layer that has a different transfer function than the paper itself. Therefor you have two separate wavefronts traveling simultaneously in the composite and this will smear or in effect change the distribution of sound over a limited range but these two waves would add and subtract from the total output. This very much goes along with my thinking in the cone material that I have developed that uses more than one type of composite material and the matrix resin. Not something that is easy to analyze, but intuitively you can see that different materials have different transmission speeds of sound.
Thanks for the clear explaination!
A question OT... can you repair small scratches in the diaphragm with this method?
That lacquering is a story in itself. I am just working on coating wizzer cones in wideband drivers. Normally i make 3 coats with different materials.
For example the first coat can be made lightly or it can be very thick so that the lacquer goes deep into the rather thin paper of the wizzer.
Too much and i loose high treble energy and too little the response stays a bit ragged.
It is also important how long you dry the coatings until the next one is made.
Also the lacquer needs a certain time to dry until it is settled.
Measure after some hours and measure after a week and the response is different.
This is a tricky business but kind of fun.
What is the membrane material that you want to repair and how big is the scratch ?
When it is paper and the scratch is small you can use white wood glue that dries out transparent. When only a tiny area of the cone is affected it will not have a big effect on the sound.
To repair metal membranes is harder. Ones they have deformed it is nearly impossible to get them back to shape.
For example the first coat can be made lightly or it can be very thick so that the lacquer goes deep into the rather thin paper of the wizzer.
Too much and i loose high treble energy and too little the response stays a bit ragged.
It is also important how long you dry the coatings until the next one is made.
Also the lacquer needs a certain time to dry until it is settled.
Measure after some hours and measure after a week and the response is different.
This is a tricky business but kind of fun.
What is the membrane material that you want to repair and how big is the scratch ?
When it is paper and the scratch is small you can use white wood glue that dries out transparent. When only a tiny area of the cone is affected it will not have a big effect on the sound.
To repair metal membranes is harder. Ones they have deformed it is nearly impossible to get them back to shape.
I do believe that you can alter properties by creating a lacquer/Paper sandwich. I also use that kind of design in my speakers, the harder material. (mine is ceramic or Diamond) keeps the breakups at high frequencies, the softer (aluminium) keeps the Q low som when the stiff cone breaks up it does it softly. For me theres no other way than Pistonic. Designing drivers with mechanical absorption (in the membrane) controlling the frequency response is a dead end. Reason is that mechanical absorption is so dependant on the SPL levels. So you driver simply sound different at different levels. result is that the sound field becomes nervous, veiled and not very natural.
Joachim,
Though I don't go for a single driver myself I can appreciate that you have pursued that application. I will go as low as two devices and that is about it. but I do think that drivers can sound good even outside of their pistonic range. It just takes a more thorough device design concept to pull that off well. Being locked into only using devices in their pistonic range is going to require many drivers to cover the entire frequency response range even if you do not attempt to go as low as 20hz. Then we have to deal with all the crossover points and all the problems associated with that method. There surely is no free lunch and any way you look at it you have to make some kind of compromise at some point.
Though I don't go for a single driver myself I can appreciate that you have pursued that application. I will go as low as two devices and that is about it. but I do think that drivers can sound good even outside of their pistonic range. It just takes a more thorough device design concept to pull that off well. Being locked into only using devices in their pistonic range is going to require many drivers to cover the entire frequency response range even if you do not attempt to go as low as 20hz. Then we have to deal with all the crossover points and all the problems associated with that method. There surely is no free lunch and any way you look at it you have to make some kind of compromise at some point.
You can see the measurements from post 301.
http://www.diyaudio.com/forums/full-range/162827-mpl-11.html
Show me a multiway that can do this, especially phase linearity and sensitivity.
We are working on a version that is even more linear in the treble,
http://www.diyaudio.com/forums/full-range/162827-mpl-11.html
Show me a multiway that can do this, especially phase linearity and sensitivity.
We are working on a version that is even more linear in the treble,
Hi Joachim
it's an RCA 9449 driver with paper cone. May I send you some images from it that you can have a look onto? Would be so kind... and we can discuss this by another channel and not entering the thread.
I'll send you them via Suesskindaudio - is this ok?
Another nice thread on cartridges here at DIY: http://www.diyaudio.com/forums/analogue-source/238187-inside-cartridge.html
Another nice thread on cartridges here at DIY: http://www.diyaudio.com/forums/analogue-source/238187-inside-cartridge.html
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