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Custom DIY 8" Fullrange Driver
Custom DIY 8" Fullrange Driver
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Old 2nd June 2017, 04:43 AM   #11
theaudiopath is offline theaudiopath  Australia
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Dear Krakatoa.
If it wasn't difficult to create extended or fullrange drivers with real world linear response where are they all? There is more than one moving part. cone, suspension, spider and the leads from the voice coil. To a lesser degree the basket will vibrate or resonate. Yes it is on first glance a simple device but as a "fullrange" loudspeaker it's task is anything but. It is a VERY inefficient transforming electric into acoustic energy with at the very best 5% efficiency. On top of that it has to produce say 30 Hz
right though to 18-20 KHz from the same cone all @ the same time! Unless you go to the brute force of an electro magnet getting the magnet to deliver its field of magnetic force to the voicecoil in a smooth contolled & predictable way is neither easy or cheap. The cone has to be both light and rigid, damping resonance without storing the energy created by the sound it produces. Ideally it should be one piece & seamless. The only way I could see that happening @ home is a carbon capable 3D printer
IF you have the means to afford one.
Seing you think it's so doable why don't you show us all how it's done & build one yourself. Very easy to criticise but you would help us all by creating a solution.
Kindest regards Mark
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Old 2nd June 2017, 08:18 AM   #12
krakatoa is offline krakatoa  Romania
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I am aware of everything you said there but the perspective is on the pessimistic side, it's still one moving part (yes... a voice coil attached to a few things) the complexity is minute compared to what is going on in a cell phone or other things we have and take for granted... it's the cone that makes the sound and that's where the real problem is. Again - it's not me (the costumer) who has to prove that I'm right, I don't have the experience and tech they have to make a meaningful attempt at making a "perfect" fullrange driver - the manufacturers who have a history of lying to the costumer in specs for example, fantastic claims about products etc, prices that have nothing to do with manufacturing costs etc. - you understand where the problem might be? it's not a technical issue... it's a social issue.
I was hoping to hear a second opinion from someone who has made some diy attempts at designing a fullranger, not to have a technical discussion on how it's done, I'm not in the position to know.
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Old 2nd June 2017, 09:28 AM   #13
ICG is offline ICG  Germany
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Originally Posted by ghemml View Post
No measurements available yet, i am still in the process of assembling them. One more motor assembly to go, and it is going to be a pain to do that.
Did you use wood or plastic wedges? That makes the 'snap' a lot more predictable.

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Originally Posted by ghemml View Post
But for starter I will do up the TS parameters measurements and post up here. Followed by building the enclosure and frequency response.
Ah, nice! TY Distortion response would also be greatly appreciated.

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To be honest i never reinvented the wheel, i simply looked at lowther, AER, Feastrex, Voxativ... Etc as a base guide towards my design.

But the key features of my fullrange is, phenolic dampers and paper VC.
No need to reinvent the wheel but you could make use to some of the nice features you've included. The spider is a great idea and allows you to access the voice coil former below the spider. You could get the leads to connect there, no need to run them across the cone at all. That way you could keep the weight closer to the center and it makes the assembly of the cone more convenient. You could also quite easy separate cone and VC again by dissolving the glue (i.e. with acetone).
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Old 2nd June 2017, 10:01 AM   #14
ICG is offline ICG  Germany
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Originally Posted by krakatoa View Post
What really strikes me about the design is the fact that manufacturers can't make a good 5" unit (cone is usually too deep for good dispersion) but a home made driver with basically just a piece of paper can make a 8" unit with a very wide cone... presumably stable cone.
Well, the narrow cone actually does have some advantages. They usually aren't exactly cone-shaped, it's often a more exponential shape which allows for a wider and more controllable transient break-up. That's not better or worse, it's different weighted attributes which each can be valid for a number of reasons, depending on what you want to achieve.

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Horns - reminds me of how the +800$ SEAS Exotic X1-08 has it's wizzer shaped (anybody at Seas heard about offaxis response?)...
Click the image to open in full size.
They are seemingly rather narrow-minded. Well, that's okay for some uses, most ppl really need a wider dispersion though.

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again something tells me designers of cones are narrow minded because in this age of computers and materials and simulations and high potential for good control quality people are still looking back at designs from the vintage Altec era; Fostex has those weird shapes on the Sigma series - don't know for sure - but most likely to stabilize cone and in the case of larger cones (6.5" & 8" Sigma series) to get rid of wizzer cones... not really high tech at the end of the day...
Ah, well, tbh, Fostex often does some things just to make something different without it always being better. Some of the newer, more exotic drivers seem to have some advantages but some with the same features are clearly worse than what they have had before.

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Originally Posted by krakatoa View Post
What I'm talking in general about is that there seems to be a general lack of will from the manufacturers to get it right... Fostex sells a bunch of drivers in the WK series with a 10 db peak in the 5-7khz region - that must be ok with them otherwise somebody in some office in Japan would have rejected that (those) cone for not being good enough- and say to the developing team "NO! go back and make it right this time! nobody wants a 10 db peak in the middle of a listening experience!".
Well, the WK series is a good example. The peak is something you could live with, because you can easily filter that, the dive at the upper end however is probably not. Okay, maybe these drivers are meant to be used with a supertweeter but what's the point in the smaller ones?
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Old 2nd June 2017, 04:20 PM   #15
ghemml is offline ghemml  Singapore
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Quote:
Originally Posted by ICG View Post
Did you use wood or plastic wedges? That makes the 'snap' a lot more predictable.



Ah, nice! TY Distortion response would also be greatly appreciated.



No need to reinvent the wheel but you could make use to some of the nice features you've included. The spider is a great idea and allows you to access the voice coil former below the spider. You could get the leads to connect there, no need to run them across the cone at all. That way you could keep the weight closer to the center and it makes the assembly of the cone more convenient. You could also quite easy separate cone and VC again by dissolving the glue (i.e. with acetone).
Measurements will not be so early as I going overseas for a week looking for paper vendors, at the same time have a holiday

For the magnet mounting, I had a cramping system but still not yet fabricated as I spend more time designing quick release VC bobbins and refining my winding machine. But sure enough the magnet mounting system definitely needs to be constructed.

I understand your point on the lead out, I saw a few China made speakers using the method you mentioned. I did saw one driver in particular, they glue the lead out on the wedges of the spider which is quite interesting. I can try it out in the later stage.
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Old 2nd June 2017, 04:24 PM   #16
ghemml is offline ghemml  Singapore
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Quote:
Originally Posted by krakatoa View Post
Horns - reminds me of how the +800$ SEAS Exotic X1-08 has it's wizzer shaped (anybody at Seas heard about offaxis response?)... again something tells me designers of cones are narrow minded because in this age of computers and materials and simulations and high potential for good control quality people are still looking back at designs from the vintage Altec era; Fostex has those weird shapes on the Sigma series - don't know for sure - but most likely to stabilize cone and in the case of larger cones (6.5" & 8" Sigma series) to get rid of wizzer cones... not really high tech at the end of the day... speaker drivers have 10-15 parts from which only one is moving??? how hard can it be to make a fullrange driver that can do it (the full range act) be large enough to play the low notes, good dispersion for the highs and to play with high fidelity? I don't believe any claims that it's impossible or extremely hard... I believe it's within grasp of DIY-ers - why? because its just a cone! there are no other difficult parts... we live in a world were people are building at home rockets and airplanes and cars and what not... and a piece of paper would somehow be hard to get right? no way! At the price of some of the drivers out there you could buy the machines to build one and even some testing equipments etc etc.
What I'm talking in general about is that there seems to be a general lack of will from the manufacturers to get it right... Fostex sells a bunch of drivers in the WK series with a 10 db peak in the 5-7khz region - that must be ok with them otherwise somebody in some office in Japan would have rejected that (those) cone for not being good enough- and say to the developing team "NO! go back and make it right this time! nobody wants a 10 db peak in the middle of a listening experience!".
There are a few tricks that I have learn taming the whizzer cone shout.

1. Use very thin paper for the whizzer cone, this allows more acoustic wave passes through it than being reflected back

2. Enlarge the whizzer cone. Using the theory of a horn flare, larger the flare mouth piece lower the flare freq
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Old 2nd June 2017, 05:15 PM   #17
krakatoa is offline krakatoa  Romania
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Please, have no mercy on us - tell us more about what makes a well behaved cone (tweaking an existent cone is something many will want to know about). Any reason why you couldn't get away without a wizzer? or a phase plug ? (I believe it's going to be a phaseplug in there)
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Old 2nd June 2017, 07:49 PM   #18
ICG is offline ICG  Germany
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Happy holidays then
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Old 2nd June 2017, 08:00 PM   #19
ICG is offline ICG  Germany
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Originally Posted by ghemml View Post
2. Enlarge the whizzer cone. Using the theory of a horn flare, larger the flare mouth piece lower the flare freq
Well, that's not why you want the whizzer big. The whizzer does radiate hights but - like a large dome- or cone-tweeter, the narrower it goes on the top end. And on the lower end of the whizzer, you usually want to 'start' where the cone starts to drop off. Or, to be more precise, where the breakup starts. Since you can correct the response passive but cannot correct the radiation pattern (not even with a DSP), naturally, the radiation pattern is what dictates the size of the whizzer.
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Old 3rd June 2017, 11:41 AM   #20
ghemml is offline ghemml  Singapore
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Originally Posted by krakatoa View Post
Please, have no mercy on us - tell us more about what makes a well behaved cone (tweaking an existent cone is something many will want to know about). Any reason why you couldn't get away without a wizzer? or a phase plug ? (I believe it's going to be a phaseplug in there)
Yes there will be a phase plug for my design, still not completely firm on all my design yet since this is a prototype.

But mainly to me the phase plug is to dampen the throat area which kinda shouty.
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