tinitus;
Since thadman said:
I selected a target value of 10W into 0.25 ohms. It would be a simple matter to adjust the amp for higher impedances. For the simulations I ran I used +/-8V supply for the outputs and drivers and +/-12V for for the rest of the circuit. These voltages are enough for the output power requested, and can be obtained from 6VAC dual secondary or 12VAC center tapped secondary. In theory, a 160VA transformer would work, but I would suggest about twice that so the transformer will not run hot.
Andrew;
The ribbons in my speakers are 57" long by .25" wide. They have a 2 ohm impedance. I don't know how thin the Al is. Since the length, width and thickness of the foil all effect the resistance, the 90" ribbon could difficult to predict. I really hadn't planed to do any more on the amp until the parameters are nailed down more.
Since thadman said:
I selected a target value of 10W into 0.25 ohms. It would be a simple matter to adjust the amp for higher impedances. For the simulations I ran I used +/-8V supply for the outputs and drivers and +/-12V for for the rest of the circuit. These voltages are enough for the output power requested, and can be obtained from 6VAC dual secondary or 12VAC center tapped secondary. In theory, a 160VA transformer would work, but I would suggest about twice that so the transformer will not run hot.
Andrew;
The ribbons in my speakers are 57" long by .25" wide. They have a 2 ohm impedance. I don't know how thin the Al is. Since the length, width and thickness of the foil all effect the resistance, the 90" ribbon could difficult to predict. I really hadn't planed to do any more on the amp until the parameters are nailed down more.
Andrew Eckhardt said:
I'll get to work as soon as I can, although I'm currently balancing a full engineering schedule. We'll see what I can manage. However, upon completion of midterms, I should have some extra time available.
It appears several members have attemped DIY ribbon designs. I have a source for the neodymium magnets, however the foil is a little unclear. Where have members sourced their foil? What alloys have they been successful with?
Item # Aluminum Foil, Aluminum Foil on All Foils, Inc.
Your local super market have what you need
And may even be the best you will ever find
Very thin alu foil on thin paper
I have heard a 4x50" fullrange planar made with that
Sounded very very good
But then, a different beast, 6-8ohm straight
But I can easily imagine a similar design with 1-2ohm
Also note that using thin foil on relatively heavy plastic backup film the ribbon diaphragm will be close to impossible to corrugate, which mostly is essential to ribbons, with a few exceptions which might be heavy plastics
Last edited:
I am interested in using an alloy, so in that regard all aluminum is not all aluminum. I believe 7xxx/6xxx has very different electrical/thermal/fatigue properties compared to 1xxx...which I would be quite surprised if I found aerospace aluminum being carried in the local supermarket. ha.
Well, ofcourse you are right on that
But as usually, if you can do a design that sound fantastic with such cheap material, then to me its fully sufficient
If its that good it probably wont get any better
I have had the same thoughts you have now, about the issues of plain alu foil in the signal
But it has been proven to work
Some roll out a cap, and use that
Its thin alright, but is it really any bit better
I think that what you really want to look closer at is the backup material
Again, the smaller ribbon you aim at might best be done with pure foil, and no backup material
But as usually, if you can do a design that sound fantastic with such cheap material, then to me its fully sufficient
If its that good it probably wont get any better
I have had the same thoughts you have now, about the issues of plain alu foil in the signal
But it has been proven to work
Some roll out a cap, and use that
Its thin alright, but is it really any bit better
I think that what you really want to look closer at is the backup material
Again, the smaller ribbon you aim at might best be done with pure foil, and no backup material
Last edited:
Your local super market have what you need
And may even be the best you will ever find
Very thin alu foil on thin paper
I have heard a 4x50" fullrange planar made with that
Sounded very very good
But then, a different beast, 6-8ohm straight
But I can easily imagine a similar design with 1-2ohm
Also note that using thin foil on relatively heavy plastic backup film the ribbon diaphragm will be close to impossible to corrugate, which mostly is essential to ribbons, with a few exceptions which might be heavy plastics
The supermarket stuff is good for experimenting , nothing more , poor memory and poor electrical conduction .
I have had good luck with alloy foil manufactures , I'm currently using a pretty pure alloy , used in the medical field obtained from such .
I dis-agree with tinny , Corrugating is OK on tweeters only, pretty bad on midrange or full range drivers . Corrugate at the edges only , this will give you a suspension for proper tensioning ...
Maybe we have different opinions on corrugating
Especially about what corrugating is about
Old style "ribbed" corrugating as you seem to talk about is NOT what I have in mind
I dont like that any bit either
I just took it fore granted
Materials fore the corrugating shown below, I found those in five minutes, just looking around
Rolling a piece of flagline over an old T-shirt
Mind you, this foil is the heavy type, and not the one I recommended
But it will still work fore a very good sounding ribbon
Regarding corrugating patterns, its all about imagination, and experimenting
btw, it might be worth to try a layer of leaf gold
Especially about what corrugating is about
Old style "ribbed" corrugating as you seem to talk about is NOT what I have in mind
I dont like that any bit either
I just took it fore granted
Materials fore the corrugating shown below, I found those in five minutes, just looking around
Rolling a piece of flagline over an old T-shirt
Mind you, this foil is the heavy type, and not the one I recommended
But it will still work fore a very good sounding ribbon
Regarding corrugating patterns, its all about imagination, and experimenting
btw, it might be worth to try a layer of leaf gold
Attachments
Last edited:
Maybe we have different opinions on corrugating
Especially about what corrugating is about
Old style "ribbed" corrugating as you seem to talk about is NOT what I have in mind
I dont like that any bit either
I just took it fore granted
Materials fore the corrugating shown below, I found those in five minutes, just looking around
Rolling a piece of flagline over an old T-shirt
Mind you, this foil is the heavy type, and not the one I recommended
But it will still work fore a very good sounding ribbon
Regarding corrugating patterns, its all about imagination, and experimenting
btw, it might be worth to try a layer of leaf gold
Very interesting corrugation technique. However, I would be worried about fatigue life with regards to microcracks forming on the surface of the ribbon due to stress concentrations imparted by the corrugations. Definitely something worth testing.
Gold leaf would be interesting as well.
Tinny ,
No that was not the corrugation i was talking about , Is that even deep enuff to call corrugating ?
I cannot comment on such small dimpling of the surface as shown , i would think it would be better than the typical corrugation used by most DIY .
The only downfall from what you have shown is that the ribbon will have no suspension . I would corrugate the ends and leave the dimpled surface shown .
No that was not the corrugation i was talking about , Is that even deep enuff to call corrugating ?
I cannot comment on such small dimpling of the surface as shown , i would think it would be better than the typical corrugation used by most DIY .
The only downfall from what you have shown is that the ribbon will have no suspension . I would corrugate the ends and leave the dimpled surface shown .
The ribbon is the suspension. It should be linear below the proportionality limit.
Ok
If you use a ribbon diaphragm with plastic film backup corrugating is not needed, but also not possible
It is tho exstremely essential when the ribbbon is pure foil only
Without corrugating it will rattle, a lot
Maybe it was wrong of me to bring it up, knowing that you will do it with backup film
It is possible to get a feeling of how a material will sound
Hold the diaphragm up between your fingers and blow gently on it
And you will hear how it sounds, and how it changes with different tention
If you use a ribbon diaphragm with plastic film backup corrugating is not needed, but also not possible
It is tho exstremely essential when the ribbbon is pure foil only
Without corrugating it will rattle, a lot
Maybe it was wrong of me to bring it up, knowing that you will do it with backup film
It is possible to get a feeling of how a material will sound
Hold the diaphragm up between your fingers and blow gently on it
And you will hear how it sounds, and how it changes with different tention
Last edited:
For proper tensioning , you will need to have some sort of suspension ...
Agree,
I have tried them many ways , straight foil needs to be corrugated , foil with mylar less so . Corrugated foil sounds pretty bad vs straight foil and mylar,
the difference is huge.
Why does flat foil need to be corrugated? RAAL uses flat foil, which is neither corrugated nor laminated. I think you will observe the RAAL transducers to be quite superb.
Assuming the membrane is operated above its fundamental resonance, care must be taken to suppress its eigenmodes if one desires a linear response. I believe the response coefficients of the eigenmodes will decrease at a rate of 1/J^2, where J=mode number.
Assuming the driver is crossed over high enough and appropriate damping is used, the response will be primarily defined by the primary mode shape (J=1).
We can optimize this alignment by corrugating the ribbon. This will decrease the stiffness of the membrane (ie lowering the fundamental resonance). However, I believe this may result in a non-linear reactive force (ie compliance) and will restrict the drivers usable bandwidth. (Possibly why members have observed a poor response in the midrange contributed by corrugated ribbons)
An alternative solution could involve tensioning the membrane, placing the fundamental resonance above the bandwidth of the driver. As a result, the membranes reactive force will be linear (below the proportionality limit of the membrane) and its response will be defined by the primary mode shape (J=1).
An analysis of the responses of low compliance and high compliance membranes could be quite interesting.
Any thoughts on which alignment would be the more appropriate solution?
Assuming the driver is crossed over high enough and appropriate damping is used, the response will be primarily defined by the primary mode shape (J=1).
We can optimize this alignment by corrugating the ribbon. This will decrease the stiffness of the membrane (ie lowering the fundamental resonance). However, I believe this may result in a non-linear reactive force (ie compliance) and will restrict the drivers usable bandwidth. (Possibly why members have observed a poor response in the midrange contributed by corrugated ribbons)
An alternative solution could involve tensioning the membrane, placing the fundamental resonance above the bandwidth of the driver. As a result, the membranes reactive force will be linear (below the proportionality limit of the membrane) and its response will be defined by the primary mode shape (J=1).
An analysis of the responses of low compliance and high compliance membranes could be quite interesting.
Any thoughts on which alignment would be the more appropriate solution?
Last edited: