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Multi-Way Conventional loudspeakers with crossovers

Artichoke Horn
Artichoke Horn
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Old 11th April 2017, 01:59 AM   #61
GM is offline GM  United States
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Still quite good, especially since it's not finished and seen worse from manufacturers.

GM
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Old 16th May 2017, 04:49 AM   #62
hollowboy is offline hollowboy  Australia
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I'm running this as a mono 2-way. It is good.

1) I got the miniDSP worked out.

My issue: the dedicated power supply (an external phone battery with USB ports) that I intended to use for the miniDSP is faulty / reacts oddly to the load, so it would shut down every 10 seconds. I tried skipping the DSP, using a passive crossover, and time-aligning the drivers physically (stacked driver-on-driver). The flaw was a small sweet spot - if I sat down, the mid horn blocked the output of the HF horn.

Easy fix: I now run the miniDSP off the same 12V battery* as the amp. With DSP delay, I now stack the horns mouth-on-mouth. This is a lot better.

2) My waterproofing technique (external PVA --> fibreglass bug screen --> external paint) needs to improve.

I started off trying to use huge sheets - the full 2.4m width of the roll. The problem is, it is very difficult to get a section that big to wrap around corners and lie flat. Much easier to cut the mesh into smaller sections and overlap them.

3) I'm still working on:
-smoothing / filling in the internal angles
-haven't reinforced the rear chamber
-haven't yet tried a phase plug

It sounds nice & very clear already. It has that (good-but-dangerous) property of not seeming very loud until you try to have a conversation in front of it ...and you realise you have to yell. Standing behind the horns, conversation is easy, no need to raise your voice at all. So (subjectively), the directionality is very good.**

The weak link for SQ seems to be the HF breakup of the 2" driver***. My short term fix will be to kill response >10kHz via miniDSP.

The ideal and (very) long term fix will be to keep building it up to a stereo 4-way system, and to get new (matching) diaphragms.

*A 10 watt solar panel + a charge regulator + a large (truck?) battery I rescued from hard rubbish. It was ridonculously easy to set up. Lot of alligator clips, so it looks a bit like this: https://en.wikipedia.org/wiki/Flying_Spaghetti_Monster
I haven't done the maths to see how many hours use I have - but one battery happily plays for (at least) 3 hours & I have a spare battery, so I think I have effectively infinite power.

**I should try a lap of it with a SPL meter. I guess it will show that a lot of LF is leaking.

***I'm still using the JBL / mystery speaker:

4" (JBL clone) diaphragm identification
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Last edited by hollowboy; 16th May 2017 at 04:55 AM.
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Old 23rd August 2017, 05:07 AM   #63
hollowboy is offline hollowboy  Australia
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Just minor tweaks, lately, due to laziness + wet weather. Also: no rush, since it sounds pretty good already.

I'm doing a household de-cluttering, which intersects nicely with this project.

This diffuser is an old Ikea fruit bowl, that happens to be a perfect fit. I've glued it to the rear chamber's cap, with some wool sandwiched between the plastic layers. Those raised cylinders are all open, so this wool-stuffed volume is well connected to the main part of the chamber.

I'm using wood scrap and chunks of packaging foam to break up the symmetry of the other internal surfaces.

On the main body of the horn, I'm filling / stiffening the corners, and have used very primitive external damping - milk crates filled with rocks
Attached Images
File Type: jpg cap.jpg (113.8 KB, 280 views)
File Type: jpg drum.jpg (81.6 KB, 275 views)
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Old 23rd August 2017, 04:34 PM   #64
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Old 12th October 2017, 01:18 AM   #65
hollowboy is offline hollowboy  Australia
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Next step: I'm going to go 2.1 way. I'm making a couple of 150cm long 100Hz horns, 90*90cm mouth, for 12" drivers. They'll cover about 2 octaves, with 2" horns taking over >500Hz.

The smaller size is:

-so they will fit in my van, thus I can make them in a workshop. The bigger one was made on site, and mostly with hand tools.
-so I can make them MUCH more rigid, yet still shift them.
-because I got a stack of cheap formply in < full size sheets.

In the medium term, I'll place them directly flanking the larger horn, roughly doubling the mouth area. In the long term, I'd like to mount them within larger bass horns (coaxial).

I only get a few hours per week to work on them, so this will probably be finished early 2018.

Here be construction pix + an image of the existing horn.

The form is a 4-cell multicell, for rigidity.
Attached Images
File Type: jpg overdone.jpg (237.8 KB, 221 views)
File Type: jpg skin begins.jpg (397.6 KB, 215 views)
File Type: jpg rough.jpg (424.1 KB, 214 views)
File Type: jpg Centre panel.jpg (461.3 KB, 107 views)
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Last edited by hollowboy; 12th October 2017 at 01:28 AM. Reason: clarity, grammar
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Old 12th October 2017, 06:28 PM   #66
pcgab is offline pcgab  United States
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Looks like you're off to a great start for the new horns!

Are you using the form to make the horn expansion with layers of ply?
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Old 15th October 2017, 09:01 PM   #67
hollowboy is offline hollowboy  Australia
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Ugh, ambiguous English!

I meant one of the other meanings of 'form', not "a supporting frame". That is:

The final shape and structure of the finished horn device shall be a 4-cell multicell, for rigidity.

I boosted the cross sectional area to account for the volume the bracing takes up.
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Old 15th October 2017, 11:08 PM   #68
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Ahh, that makes sense. Keep up the good progress!
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Old 4th February 2018, 11:31 PM   #69
hollowboy is offline hollowboy  Australia
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The progress has taken a while. I'm now in a better workshop (a lot more room etc), and I am making sawdust.

The current vision is to:

- sling an old 15" into the existing midbass horn, and use it over a narrower range, maybe 60Hz-120Hz (mono)
- move the 12" driver(s) to smaller mid horn(s), aiming for roughly 120Hz - 1kHz
- Switch the HF horns, go from titanium 2" to polyimide 1". This is to avoid the breakup ~10kHz
- add a fairly conventional nearfield sub using an old pair of 18" EV

I think I'll use the subwoofer as the listening chair, so that proximity gives it plenty of 'gain'. I'll cluster the midbass horns together to maximise their effective mouth size. Listening position will be ~6 metres back, so the ~2 metre spread between L and R centres should be enough.

Crossover points are approximate - they'll depend on how the clustering and positioning works.

All this subject to change, for example, I might get lazy and keep it mono.

Pictured is:

- the throat of the first mid horn (150cm long, 90x90 mouth)
- the first step in filling some of the volume between the 12" cone and horn throat
- idea* for the sub - with the midhorn and lots of junk in the background

The 1" horn I'll try is shown here Maybe Altec horn - Album on Imgur

*this is actually a wheeled day bed / storage bin that I'm making for a friend, but I chose the bracing scheme shown to get a feel for how I might put together a fairly large PPSL sub.
Attached Images
File Type: jpg throat for 12 smallpic.jpg (356.6 KB, 44 views)
File Type: jpg filling throat smallpic.jpg (337.3 KB, 38 views)
File Type: jpg daybed smallpic.jpg (360.5 KB, 40 views)
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Last edited by hollowboy; 4th February 2018 at 11:31 PM. Reason: speeling
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Old 5th February 2018, 01:09 PM   #70
pcgab is offline pcgab  United States
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Awesome news about the bigger/better workshop. Working in a small space can be so frustrating, especially when you're working on not small projects like big *** horns!

I like your idea about the dual 18 sub at the listening position. You going to use dsp for the delay?

Looks like the mid horn(12" driver is coming along nicely as well). The throat detail looks good. Do you plan to add any sort of filler, like Bondo, or similar to 'smooth' the transitions? Not sure how much difference that would make.

I thought the 1" horn might have been an Emilar eh500, or similar, but they didn't have vanes. Looks like a good find for sure.
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