Something Stirs in the Workshop

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Toppsy
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#16 Re: Something Stirs in the Workshop

Post by Toppsy »

As a fellow builder of speakers this build has my admiration and due respect. Look forward to hearing the end result. :headbang: :thumbup:
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IslandPink
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#17 Re: Something Stirs in the Workshop

Post by IslandPink »

Respect !
IslandPink wrote: Sun Dec 10, 2017 6:41 pm What Hz is the little one ?
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Ray P
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#18 Re: Something Stirs in the Workshop

Post by Ray P »

vinylnvalves wrote: Sat Jan 20, 2018 7:42 pm ...coloured gel goats do allow you to sand and buff it to a mirror finish though, without needing to spray it.
Yes, but remember that gel coats are meant to be the first layer when laminating onto a mould so the finish will reflect the quality of the surface of the mould and is easy to buff up to a smooth, high gloss if the mould has a good finish. Otherwise gelcoat will be like applying a very thick paint and will need a lot of work to cut back to a smooth finish; in fact I would say it will be nigh on impossible with the shape of your horns.

As I'm typing this I'm looking at a model catamaran hull male plug that is actually made up of layers of ply so not a million miles away from your counstruction; by applying very light coats of low viscosity epoxy and cutting back each very lightly with very fine wet&dry (used wet) I achieved a very tough, almost glass like, finish. You can pigment epoxy too.
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vinylnvalves
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#19 Re: Something Stirs in the Workshop

Post by vinylnvalves »

Mark, I don’t know what freq the small horn is, it’s a stock picture I borrowed to highlight what the wings looked like.

Ray, thanks for the advice on finishing, assume the finishing resin has some wax in it so it doesn’t dry tacky.
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Ray P
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#20 Re: Something Stirs in the Workshop

Post by Ray P »

vinylnvalves wrote: Mon Jan 22, 2018 4:24 pm Ray, thanks for the advice on finishing, assume the finishing resin has some wax in it so it doesn’t dry tacky.
You're welcome. The description for the finishing epoxy I linked to previously says "Non shrink tack free glossy surface finish..."

I should have mentioned, after cutting back the epoxy with very fine wet and dry you can refinish to a glossy shine by applying a very little epoxy like polish with a lint free cloth or similar.

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rowuk
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#21 Re: Something Stirs in the Workshop

Post by rowuk »

This is absolutely beautiful. I have been thinking about a wooden elliptical 150 Hz horn for the same reason - vertical integration. This moves my motivation to 100%. Great job!
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vinylnvalves
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#22 Re: Something Stirs in the Workshop

Post by vinylnvalves »

Nearly got to the end of building these horns.... they are just about to go into the spray shop..
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Then I started thinking have a dropped a bollock, as you know le Cleac’h horns have a big rolled lip. For the setup with I am intending using this horn this elliptical horn, I will only bring the centre of the MF and HF units only 9cm closer.
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This is when I started thinking.... should I truncate the bottom of the MF horn and the top of the HF horn which will lower the MF horn by an additional 4cm, like this
101803C0-8B2B-4E96-9745-C60F8389AC34.jpeg
As I am using a DSP I was proposing to align the mouths not the throats of the horns with time delay. Can anyone see an issue with this.

Opinions please as once removed the lip is hard to reattach :(
vinylnvalves
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#23 Re: Something Stirs in the Workshop

Post by vinylnvalves »

E493E2DD-3A32-411B-A459-491E6190707B.jpeg
(
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Not sure what went off with my pictures
Cressy Snr
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#24 Re: Something Stirs in the Workshop

Post by Cressy Snr »

All very organic. :)
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IslandPink
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#25 Re: Something Stirs in the Workshop

Post by IslandPink »

Well I'm of the opinion removing a bit of the roll-back top and bottom would be fine and probably get you a better result given the drivers are closer together.
On the time-alignment, not so sure - if you have the mouths coincident, then even with DSP, as soon as you go off axis, the phase matching between the mids and HF will start to fall apart. Just geometry. Whether you can get away with this, not sure - has to be one for listening, I think.
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vinylnvalves
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#26 Re: Something Stirs in the Workshop

Post by vinylnvalves »

Off axis isn’t that important to me, as I am selfish.... I have a hot seat. Only people who listen to my speakers off axis, are at the WAM show and Owston. :) :wink:
chris661
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#27 Re: Something Stirs in the Workshop

Post by chris661 »

I'd definitely try to get the horn mouths aligned - there's a big pile of diffraction there if you don't.

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IslandPink
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#28 Re: Something Stirs in the Workshop

Post by IslandPink »

It's not really diffraction - it's reflections coming back off the mid horn - which mostly go backwards. Romy the Cat is of the opinion the downsides of alignment of the drivers ( not the mouths ) are very much overstated - and I'd go with his judgement.
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IslandPink
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#29 Re: Something Stirs in the Workshop

Post by IslandPink »

Actually I'll rephrase that a bit , there's diffraction going on in both cases but it would help to see some information or a pic of the HF horn you're going to use, Steve. Then it would be easier to discuss the pros/cons of different approaches. Also, can you re-do the pics you just showed as you say the truncations didn't come out properly ?
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vinylnvalves
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#30 Re: Something Stirs in the Workshop

Post by vinylnvalves »

He’s some images of what I am planning to do. I will integrate the Beyma TPL horn into the bass cabinet, making the bass cabinet taller and bigger. I will the put the truncated midrange horn on top of that. I will probably contour the top of the bass cabinet so there is no step or discontinuity. The speaker is so tall as the TPL needs to be at seated ear level.
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