Tentative, an idea for a group game!

Idea for an open source project started for fun on the DIYAUDIO forum in Feb 2016!

Moderator: Graz

Tentative, an idea for a group game!

Postby Graz on Thu Feb 18, 2016 3:48 am

from the DIY forum, posted Feb 2016;-

:) Tentative, an idea for a group game!

I figured a good bit of fun would be to initiate an open-source DIY speaker, one where the project could be contributed to from all over the world, something worthwhile that many DIY enthusiasts could get involved in, with near assurance of a high quality, high end result. So here goes -

(Apogee Acoustics) “Perigee”* - OS1 DIY ribbon hybrid

(open source 1) Or something else if this doesn't float

OK. Something for almost everybody! For real.

The aim. To have a shared project of people building a 2 way* ribbon hybrid speaker that could out-perform many historical hybrids, with a first class Apogee Acoustics ribbon diaphragm that would be able to be built into a frame-magnet-array by savvy audio enthusiasts not afraid of a fair challenge. Nothing I haven't already seen in here, but with a twist to make the idea a little more attractive. Ideally the speaker would have some basic design elements that would be set for the purpose of group conformity – but after that artistic expression of the designer would be the main focus of where the project goes. Some may look at this as something to get a basic hybrid speaker together with, others may want to delve deeper. As you would be essentially building the magnet frame array for the MRTW yourselves there are options for overall design. However, I would suggest conformity in the frame-array dimensions as designed and use of the same type of magnet material and strength. This way – if you hit on a problem, group assistance is more likely. Crossovers are another area – of course these will change depending on efficiency, and how closely the ribbon's frame and magnet array conforms to group consensus – the more you keep the array standard and choice of driver the same, the better chances you could have to achieve a crossover that could be a genuine shared development for the group...

What I propose to make available is a unique to DIY forum group multi element ribbon, aluminium alloy and Kapton construction, terminated at both ends with a circuit board. The ribbon would be a new design, a modern day equivalent to the MRTW units found in the early Apogee Centaur and Stage speakers, capable of fine performance. A bit bigger though, not identical to the Apogee units. Classic Apogee+ quality. They would be supplied as pairs and with the tensioning instructions relevant to the design. The frame-magnet-array would be an achievable task for many, certainly a challenge, involved but not anywhere near as prone to failure as a panel bass renovation!

Essentially – the DIY person would have to build everything else. The actual ribbon Magnet array, speaker box/baffle front, crossover, driver choice, finish would all be part of the DIY challenge! Lots of places to impart design and personality. It would make sense to cone debate driver partner options in here (ideally) or on the Apogee Acoustics forum in the diy area. Choice of driver(s) would be important of course, remember this is DIY – so choosing a madly expensive cone set would limit the group size that would want to work with it! Being a maverick is fine but ultimately better results would come from a larger group. If there is enough interest in this perhaps group buys of magnets, or supply of metal work in local regional groups could be a good idea – not everybody has expensive equipment to machine metal, though some of you will own, or have access to such equipment.

The actual ribbon design. The unit would have a dc resistance in the 3-4 ohm range, something nice and easy to work with. Working length around 28-32” I would guess, though nothing set now as I can essentially make most anything here. Typically the ribbon would require block magnets about 20x25mm (3/4” x 1”), and with good quality modern ceramic would be in the 87-88db range. Bigger magnets, or stronger magnets = harder to work with, and more importantly unpredictable results vs a group project, so I would suggest not going there! Magnet costs are often in “flux” subject to change so hunt around! And I know neo's are trendy, but they throw a whole lot of other things into the equation, not such a good idea for everything...

My plan/aim is to cap the price of this specialised ribbon diaphragm, limited to $400 per pair (Feb 2016). Typical air mail costs for such a ribbon would be in the range of $50-70 insured air to most destinations worldwide, less if shared shipping. That's the MRTW diaphragms only – you would have to factor in cost of the ribbon magnet array, cones, wiring, crossover*, terminals and all other box work...

As mentioned, the frame and magnet array would be part of the DIY – plans would be issued here, but sourcing regular sized steel for the frame, frame ends, and ceramic magnets would be the task of the builder. Now here is where the project can get more exciting – I suggest not one but THREE camps for implementation!

The camps;-

Flat baffle, rear box for cone(s), a sealed system, 2 way
Flat baffle, rear box for cone(s), a reflex system, 2 way, bass tuned port
Flat baffle, dipolar, cone array

So this is a tentative idea at present. Who wants to play?

Email me from the http://www.apogeeacoustics.com website to express interest. Numbers of people genuinely interested will dictate if this project flies – I believe it could be fun, and would be interested to see where it goes...

First up - What do you guys think?

Curious - Graz
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Re: Tentative, an idea for a group game!

Postby Vansloneker on Thu Feb 18, 2016 9:56 pm


I had not expected this. I logged on by coincidence for another reason and stumbled upon this idea. It's great!

Biggest challenge I think will be developing a crossover filter.
poor guy
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Re: Tentative, an idea for a group game!

Postby Vansloneker on Fri Feb 19, 2016 6:07 pm

I wonder of the ribbon will function in -an array of- electromagnets?
poor guy
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Re: Tentative, an idea for a group game!

Postby TinyTim on Sun Mar 27, 2016 6:19 pm

I was always intrigued by these speakers

Floating Synthesis 5.jpg
Floating Synthesis 5.jpg (204.59 KiB) Viewed 1068 times

The ribbon could hang in mid air between a magnetic field. Well, ok, it was far fetched but the design could be cool. I would be interested in a little DIY just for fun.
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