I assume you glued the magnets to the strip.
In that case you can make something like this.
To avoid glueing the jig to the metal/magnet you can use non sticking tape.
BR,
Henjo
ah nice, i think PE would be a good candidate that wont stick much on the glue. ats its easy to machine and get in thick pieces..
Well with a 4mm gap my metal holds
still gained about 3-5 db over the small version of 21cm. 3 db for 4 magnets is a good trade i guess.
Small video, dont mind my english, always having hard time with a camera and also adjusting languages
This version has a membrane of 30 cm high
https://youtu.be/boIiPzwAbeU
This version has a membrane of 30 cm high
https://youtu.be/boIiPzwAbeU
ah nice, i think PE would be a good candidate that wont stick much on the glue. ats its easy to machine and get in thick pieces..
Well with a 4mm gap my metal holds
Hi Wrine,
I didnt quite get the ideea of how you gained 3dB? I didnt understand so well.. Can you be more explicit please?
Thanks in advance.
Sergiu
Small video, dont mind my english, always having hard time with a camera and also adjusting languages
This version has a membrane of 30 cm high
https://youtu.be/boIiPzwAbeU
I have to say that I have always been impressed by this speaker. It has really really good dispersion, clear and precise sound and a very good projection and imaging..
Well done my friend.You can barelly hear those resonances through the recording. For the verticall dispersion that you sayed that its poor you can try to make the sustaining plates from above and bellow more narrow so that you can use some "V" shape wood or metal to disperse the sound that's comming from the interior of the cilinders. But again, for that you need the cylinders to be full round not cutt in half. And if you use full cilinder you have resonances again..
Cheers
Sergiu
wel i gained 3-5 db in output going from the 21cm version to the 30 cm versoin. even with increasing the gap width from 3 to 4 mm. there are 14 magnets in the whole thing compared to 10 in the 21cm version. (so 2 more for each metal bar)
i might even got higher if my coil dc resistance did not measure 4.2 Ohm instead of the 3.4 ohm needed to get a 4 Ohm impedance. i did not measured impedance of this version yet so i might be wrong.
I have to say that I have always been impressed by this speaker. It has really really good dispersion, clear and precise sound and a very good projection and imaging..
Well done my friend.You can barelly hear those resonances through the recording. For the verticall dispersion that you sayed that its poor you can try to make the sustaining plates from above and bellow more narrow so that you can use some "V" shape wood or metal to disperse the sound that's comming from the interior of the cilinders. But again, for that you need the cylinders to be full round not cutt in half. And if you use full cilinder you have resonances again..
Cheers
Sergiu
There where no resonances in this recording
. but vertical dispersion is no problem i think its even a benefit when your room acoustics suck. bad horizontal dispersion helps to , but i hate to be pinned in the middle and cant even enjoy a movie with my girl. without panning the speakers since i do care about a phantom mid. reflecting the sound comming form the cylinders back to the listen position with the angles is not a good idea in my opniion, you get some free peaks and dips There are a few things i want to change
1. i need to stiffen the coil somehow without adding much weight and thickness.
2. i need to find a way to create 2 equal half cylinders where the coil is exactly in the middle at the desired angle. since i got the elastics to position the coil in the gap but when one one cylinder is slightly different from the other, it will push the coil diagonal in the gap, and thats pretty hard to control with the elastic bands over the total length of 30 cm. if one place is fine it rubs at another place. keep adjusting strings , getting anoyed by it. (this was more easy with the smaller version i made)
3.creating a nice glue seal where the 2 papers that form the cylinders split from one another. its hard to glue at such a straight line. but have to be more precise. using templates or something.
4. get thicker bands, these elastics break and sometimes slip out of the fastener (i used the inner parts of a connector block)
5. a way to stiffen the paper where the 2 cylinders meet (few centimeters or whole paper since the rest of the membrane does not care about the weight), this increases the high frequency by a few dB
i could also add more elastic bands to control the coil, since mid high fequency does not care at all about the strings. but its rather complicated ...
any one have an idea of anyhting stiff that does not weigh much ? i though about alumnium maybe ? but what sort, house hold foil wont cut it
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Hi Wrinex,
I also struggled with point 1 to 4.
My advice from experience is:
Work very accurate.
I stiffen, glued the paper and coil in one go with epoxy resin reinforced with carbonfiber..
The part where the two membranes split I have used 1mm EPDM rubber.
This gives nice tansition and prevents the epoxy resin from running to unwanted places.
I don''t need elastics to center the membranes.
As you can see in this picture.
http://www.diyaudio.com/forums/planars-exotics/69450-diy-ribbon-speaker-different-kind-36.html#post4380419
Henjo
There are a few things i want to change
1. i need to stiffen the coil somehow without adding much weight and thickness.
2. i need to find a way to create 2 equal half cylinders where the coil is exactly in the middle at the desired angle. since i got the elastics to position the coil in the gap but when one one cylinder is slightly different from the other, it will push the coil diagonal in the gap, and thats pretty hard to control with the elastic bands over the total length of 30 cm. if one place is fine it rubs at another place. keep adjusting strings , getting anoyed by it. (this was more easy with the smaller version i made)
3.creating a nice glue seal where the 2 papers that form the cylinders split from one another. its hard to glue at such a straight line. but have to be more precise. using templates or something.
4. get thicker bands, these elastics break and sometimes slip out of the fastener (i used the inner parts of a connector block)
5. a way to stiffen the paper where the 2 cylinders meet (few centimeters or whole paper since the rest of the membrane does not care about the weight), this increases the high frequency by a few dB
i could also add more elastic bands to control the coil, since mid high fequency does not care at all about the strings. but its rather complicated ...
any one have an idea of anyhting stiff that does not weigh much ? i though about alumnium maybe ? but what sort, house hold foil wont cut it
I also struggled with point 1 to 4.
My advice from experience is:
Work very accurate.
I stiffen, glued the paper and coil in one go with epoxy resin reinforced with carbonfiber..
The part where the two membranes split I have used 1mm EPDM rubber.
This gives nice tansition and prevents the epoxy resin from running to unwanted places.
I don''t need elastics to center the membranes.
As you can see in this picture.
http://www.diyaudio.com/forums/planars-exotics/69450-diy-ribbon-speaker-different-kind-36.html#post4380419
Henjo
looking nice, but do you got any measurements ? since im worried about weight and high frequency responce on ur design. and maybe im wrong and i can beef things up to
Ok, if I can find some time today i"ll do a view measurements.
At the same time I can test my measurement app. on the phone.
My other measurements with the heavy paper are here
BTW What kind of DSP do you use?
I use minidsp with 4 Hypex modules.
Henjo
i used mini dsp as well. mostly for test purposes. i got bunch of TPa 3116 boards that i would like to put to use for once. but in the end if i could make it passive i would do it right away. thats why i want the best freq response without using my minidsp. i could easy get rid of the peaks and dips with the dsp. but thats not the the trick dips and peaks usually indicates something is wrong or just to heavy.
reason for passive is that i might want to sell some complete speakers, and i rather make these as simple as can be(for theres and my sake ). like 6db oct filters or maybe 12db. most people love to use there own amplifier. also with 4 hypex and a minidsp things get expensive fast.
btw weird you still got to almost 20 khz with such heavy membrane. some heavy eq in the mindsp to get to that verry good looking end result there.
you system faslls off from 500hz as well. its weird, my small one did that and the big one to.
dips and peaks usually indicates something is wrong or just to heavy. reason for passive is that i might want to sell some complete speakers, and i rather make these as simple as can be(for theres and my sake ). like 6db oct filters or maybe 12db. most people love to use there own amplifier. also with 4 hypex and a minidsp things get expensive fast.
btw weird you still got to almost 20 khz with such heavy membrane. some heavy eq in the mindsp to get to that verry good looking end result there.
you system faslls off from 500hz as well. its weird, my small one did that and the big one to.
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Btw what grams/m2 did you use first and now ?
because im thinking of using or trying aquarel paper hot pressed. maar dat is alleen vanad 180grams beschikbaar
Yes the heavy membrane was heav(enl)y DSP-ed.
But the end result was fabulous.
Never heard so much space and "be there" in a DIY system.
My first one was 200 gramms/m2.
For the small one I use 120 gramms/m2 (heavy pressed aramid paper)
Here a Q&D measurement without DSP.
The low end From 400Hz could this be the cancelling out of the dipole?
Henjo
Hi Henjo,
Your measurements are interesting. Wrine was right. This speaker is really influenced by the paper quality.
I searched allot for 60 or 80 gr/sqm rice paper. I have heard that cotton paper is also worth a try. The problem is that I didnt find heavyer gramages for these two types of paper...
Henjo have you tried 80gr/sqm?
I am thinking, what if we try a more rigid membrane, I mean a heavy support, made from 180gr/sqm and 60gr for the cilinders. This way it will be easyer to centrate and suport the coil and have a light membrane at the same time..
What do you say my friends?
Cheers
Sergiu
No this was meant to be as a joke.
You had no third option.
The third option is mine. The magnets rotated 90°.
In this case you need 50 magnet per speaker.
See the cross section in the simulation!
Henjo
No, I didn't tried. And if you ask me it is not rigid enough.
As an engineer I work with facts en figures.
I'm not waiting for the lucky shot.
Some properties have to be figured out.
For short:
Wat is the influence of the physical properties? (dimensions and configuration)
Wat is the influence of the material properties? (paper, iron, ,copper, aluminium and others)
What is the interaction between the two?
If we want to make it a common issue we have to make a matrix and fill-in the missing fields.
Want do you think of it?
Henjo
I'm ok with this. I have magnets for a stereo set so I will try two choices at a time. The biggest problem that I see here is that I dont have a printing machine and a source for flexible pcb like Wrine has..
I think I will try double sided aluminium coil like in the AMT thread.
This month I will buy the steel plates and begin the assembly and coils.
It will be extraordinary to try at the same time me, you and Wrine diffrent configurations and fill up a table of relations between diffrent materials and sollutions for this speaker. For me this is an incredible speaker, with allot of potential, not easy to built (because tge strenght of the magnets) but cheap for what it has to offer. And it is ashame if we let it in a "close case" stage.
Im in with the tests. I allready buyed screws, magnets, double adhesive tape, cooking aluminium foil for the coil, aluminium pipes,and 10m of 60gr/sqm paper for the first tests. I only need the carbon steel plates.
Cheers
Sergiu
I'm ok with this. I have magnets for a stereo set so I will try two choices at a time. The biggest problem that I see here is that I dont have a printing machine and a source for flexible pcb like Wrine has..
I think I will try double sided aluminium coil like in the AMT thread.
This month I will buy the steel plates and begin the assembly and coils.
It will be extraordinary to try at the same time me, you and Wrine diffrent configurations and fill up a table of relations between diffrent materials and sollutions for this speaker. For me this is an incredible speaker, with allot of potential, not easy to built (because tge strenght of the magnets) but cheap for what it has to offer. And it is ashame if we let it in a "close case" stage.
Im in with the tests. I allready buyed screws, magnets, double adhesive tape, cooking aluminium foil for the coil, aluminium pipes,and 10m of 60gr/sqm paper for the first tests. I only need the carbon steel plates.
Cheers
Sergiu
Hi Sergui,
I have a few questions about your voice coil.
Starting with a few facts.
I simulated the voice coil in your model here
The amount of turns depends on the diameter of the copper wire.
The width of this voice coil has a maximum of 5mm for 0,224mm wire.
The force on the voice coil is 8.43 Newton.
2,4mm for the 0,18mm wire. F=5.57 N
1,3mm for the 0,15mm wire. F=3.17 N
The moving mass of the total membrane is approximately:
Mass[paper]x55% + Mass[voice coil] + Mass[glue or epoxy resin] + Mass[reinforcement].
Why 55%? 45% doesn't move only partly bends.
For example:
Your Janus50 paper area is (0,5 x 0,4)*2 = 0,4 sqm * 55% = 13,2 gram of moving paper mass if you use the 60 gram/sqm.
If you use 0,224 mm wire:
You have 0,45 gram/N
If you use 0,18 mm wire:
You have 0,348 gram/N
If you use 0,15 mm wire:
You have 0,254 gram/N
As you can see, a heavier voice coil is more efficient then the lighter one.
The heavier the paper the more efficient the heavy voice coil. (relative to the lighter coils of course)
In this case 0,224 is the maximum, because the maximum width is 5mm, if you want to have a underhung motor and a p-p stroke of 4mm.
My question is:
How would you achieve this with an alu foil voice coil?
What do you use as a voice coil carrier?
Or do glue them right on the paper?
Why these questions?
I want to protect you for the pitfalls I was in.
BR,
Henjo