Open Baffle Project

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Dr Bunsen Honeydew
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#16 Re: Open Baffle Project

Post by Dr Bunsen Honeydew »

Go ahead if you want to fry any wide band amplifiers. That is not cable that is a capacitor.
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Ray P
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#17 Re: Open Baffle Project

Post by Ray P »

SimonC wrote: Fri Apr 14, 2017 11:06 am
Ray P wrote: Fri Apr 14, 2017 7:30 am To get things rolling I've agreed a deal to purchase Phil's pair of Fostex FE167E drive units, which I plan to pick up at Owston in a couple of months. That means the project will take a little time to get rolling but in the meantime I can scout for a pair of the Eminence units and start working on the baffles and bounce a few ideas around.

Ray
Hi Ray,

I have a pair of 15" Eminence Beta's you can have on extended loan to get you going if you don't manage to find any before Owston. My circumstances (both location and time to build anything with them) have changed since I acquired them and it would be good to hear someone making use of them. Eventually I'll beg them back, but it won't be for a few months/years. I need to put in a couple of RSJ's, remove a wall and build an extension first :)

Let me know and I can drop them in the car for Owston.

Simon C
That's very kind of you Simon, I'll take up your offer if I may.

Ray
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#18 Re: Open Baffle Project

Post by Ray P »

pre65 wrote: Fri Apr 14, 2017 8:52 am Ray, if you remind me before Owston I'll throw in the two inductors I was using.

They are only cheapies, but will establish the value before splashing out on expensive ones. I seem to remember Nick saying that the inductor value was not critical.
Thanks Phil. Every little helps!

Ray
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Greg
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#19 Re: Open Baffle Project

Post by Greg »

Cressy Snr wrote: Fri Apr 14, 2017 12:25 pm Twisted twin CAT5 speaker cable....anybody still using that?
Yes, I am. I've tried several alternatives including some expensive stuff. Nothing so far has bettered it.
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pre65
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#20 Re: Open Baffle Project

Post by pre65 »

There was a pair of Beta 15" on E-bay.

I told Ray about them this morning, but it seems they are gone now.

Was it you Ray ? :)
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Ray P
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#21 Re: Open Baffle Project

Post by Ray P »

I want to bring something to the party rather than just reproducing what has gone before so...

For a long time I have pondered the idea of building a speaker cabinet using plaster but have never found the time to put it into practice. An open baffle is much simpler than a box when trying to think through the practicalities of working with plaster; being open backed means I can work much more freely and so, hopefully, be able to get a good layup of plaster without lots of voids. So my plan is to construct the baffles, essentially as U channels, using this stuff;

http://www.craftmill.co.uk/casting-moul ... 12sqm-slab

It's the stuff hospitals use for making casts for limb fractures and they seem pretty strong; you can toughen the plaster more by adding a little PVA to the water and a good tough finish should inhibit the plaster crumbling at the edges.

I'll make a mould from sealed MDF and lay up the plaster inside so the outside has a good finish. Should me a messy but satisfying experience!

Cost wise, I don't think there will be much in it compared with birch ply, not pennies but still cheap enough to treat as a learning opportunity.
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#22 Re: Open Baffle Project

Post by Ray P »

pre65 wrote: Fri Apr 14, 2017 3:01 pm There was a pair of Beta 15" on E-bay.

I told Ray about them this morning, but it seems they are gone now.

Was it you Ray ? :)
I saw them Phil but didn't bid because of Simon's offer. The listing just ended with no bids so perhaps they'll be relisted.

Ray
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Greg
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#23 Re: Open Baffle Project

Post by Greg »

Blimey, Ray. Won't they weigh a ton?
On that eBay listing that's just finished, if you're interested, try and contact the seller and make him an offer. You never know, you might get lucky.
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#24 Re: Open Baffle Project

Post by pre65 »

Greg wrote: Fri Apr 14, 2017 3:31 pm
On that eBay listing that's just finished, if you're interested, try and contact the seller and make him an offer.
I reckon that's what someone else has done Greg.

I remember once trying to make a turntable plinth using a bag of "post mix" I had left over.

Disaster. :lol: :lol:
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Ray P
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#25 Re: Open Baffle Project

Post by Ray P »

Greg wrote: Fri Apr 14, 2017 3:31 pm Blimey, Ray. Won't they weigh a ton?
I imagine they'll be a 'substantial' lift Greg, but that's OK.

I think Phil was considering a bid, I'll wait and see how the project works out with the loan Beta 15 units.

Ray
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#26 Re: Open Baffle Project

Post by Ray P »

pre65 wrote: Fri Apr 14, 2017 3:37 pm I remember once trying to make a turntable plinth using a bag of "post mix" I had left over.
With the plaster bandage I linked to you can build in a more controlled way, a layer at a time rather than just pouring.

Ray
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#27 Re: Open Baffle Project

Post by Ray P »

Now, thinking further on the possibilities of plaster, it would be relatively simple, and no more expensive, to replicate the shape of the Quasar baffles. Hmmm...

I have some drawings of the Quasar baffles somewhere.

Ray
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#28 Re: Open Baffle Project

Post by IslandPink »

Sounds like a nice project - that sort of plaster could be very dense and non-resonant. The Perspex gains by being very dead in the upper mids and treble compared to wood, but this could go one stage further. How thick do you think the material would be ? James's are 15mm Perspex, my wood/Perspex ones use 20mm on the front panels.
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#29 Re: Open Baffle Project

Post by MJK »

I would recommend two 15" Eminence drivers per side (Alpha 15A or Beta 15A depending on your bass needs/preferences) to better match the efficient Fostex FE-167E.

I would also recommend simulating your design using the free BASTA program from Tolvan research to get a better idea of the response and potential crossover designs.

http://www.tolvan.com/index.php?page=/basta/basta.php
Martin
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#30 Re: Open Baffle Project

Post by Ali Tait »

Martin, I'm currently using one of your OB designs - B200 and twin Alphas per side. I'm looking for a bit more detail in the bass. Would It be a good idea to go for Betas, or would you have another suggestion?
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