Something stirs in the Undergrowth

Dedicated to those large boxes at one end of the room
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IslandPink
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#2656 Re: Something stirs in the Undergrowth

Post by IslandPink »

Good info, thanks Simon.
I will end up with wooden reinforcing outside of the panels because I have to calculate and shape the curve onto something solid first, to attach the fibreboard onto.
More incremental progress here .
I have decided the mouth section will have to attach separately , from roughly this point onwards, otherwise making and reinforcing that will be a nightmare, having to bring the whole thing in and out of the house.
Horn1p9m_assembly6.JPG
I will try & set up the drive unit tomorrow or Monday and have a quick listen.
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JamesD
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#2657 Re: Something stirs in the Undergrowth

Post by JamesD »

Nice to see real progress on this horn and I really hope it performs to your expectations!
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#2658 Re: Something stirs in the Undergrowth

Post by IslandPink »

Thanks.
I haven't put up any predictions before so here it is :
Expansion data in cm, cm^2 and L -
Horn1p9m_data1.JPG
SPL for 2-pi , although at 100Hz it's likely to be operating more in 1-Pi. There's less ripple in 1-Pi.
Nothing to write home about, but past experience suggests horns in this range sound better than they look on paper :
Horn1p9m_data2.JPG
Phase flatness is what I'm aiming for , although these days with Hornresp giving you the option to dial-in the unwrapping delay, I'm less sure I know what's actually going to be delivered. if I put in the actual length , I get about 5.5msec, and this graph looks quite poor, but I know this isn't the case with longer horns like, this -they have the sound of good phase, if you know what I mean. This plot with 6.1 or 6.2msec is the best I could expect !
Horn1p9m_data3.JPG
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JamesD
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#2659 Re: Something stirs in the Undergrowth

Post by JamesD »

That looks promising!

How will it integrate with the passbands on each side of it?.

With Horn Response do you find the simulation ripple shows up in practice? When I compared simulation ripple in the passband against measurement for the Quasars I didn't see much correlation at >1M measurement distance - I think because the room effects including floor bounce dominate the performance up to around 1KHz.
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IslandPink
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#2660 Re: Something stirs in the Undergrowth

Post by IslandPink »

Passbands, OK, the Yuichi with the 288-H comes up between 500 and 700Hz and is pretty blameless from there , so the idea is to get the longer horn to come down around the same point, then die off quickly. There is some acoustic LP effect by having a small chamber near the driver, and having the driver fire in sideways. However, just listening now for first time, there's still a fair bit of upper midrange treble coming through, and I will have to use electrical more.
( Pic later ).
I'm intending to have the Yuichi only 1 wavelength forward at 600Hz. It was surprisingly OK ( Nick heard it ) with the folded horn and the Yuichi at 2 wavelengths back.
Lower down, I have the tapped horn which will have to blend in around 100Hz. I might be able to get the lower-mid and tapped horns time-aligned , if I have the tapped horn about 1m nearer to me , up the room and off to the side. That would be handy. I'm hoping it doesn't matter too much where I place it, if the freq is mainly below 100Hz.

You are right that that ripple might go unnoticed, there's a lot going on with the room, below 400Hz. When i did some laborious tests with a Radioshack meter and discrete frequencies, with the folded horn, i did get a reasonably good fit to theory if i did 3 or 4 test positions for the meter and averaged them. However it wasn't to the level that would show ( or otherwise ) that level of ripple. Now with the Behringer test interface i should be able to get something more detailed.
"Once you find out ... the Circumstances ; then you can go out"
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IslandPink
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#2661 Re: Something stirs in the Undergrowth

Post by IslandPink »

1.3m of partial goodness :
Horn1p9m_firstTest.JPG
Some tone and dynamics developing in the upper bass guitar area, promising , rather too much >600Hz energy. Pretty loud ( of course )
Still 0.6m to go.
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IslandPink
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#2662 Re: Something stirs in the Undergrowth

Post by IslandPink »

This evening I had to make another piece of wood.
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Ray P
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#2663 Re: Something stirs in the Undergrowth

Post by Ray P »

IslandPink wrote: Wed Jul 08, 2020 8:01 pm This evening I had to make another piece of wood.
You've turned into a tree?! :shock:
Sorry, I couldn't resist!
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#2664 Re: Something stirs in the Undergrowth

Post by IslandPink »

No - good guess - part of my recycling ethic - one piece of 18mm birch ply, almost big enough .. needed an offcut to make it sufficient !
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#2665 Re: Something stirs in the Undergrowth

Post by IslandPink »

It took me a long time to get my head around this next piece of wood. It's good that it has instructions written on the side, about how to do the other piece ! Did a quick check last night on sound, it's progressing usefully.
Image
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IslandPink
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#2666 Re: Something stirs in the Undergrowth

Post by IslandPink »

Some mouthparts :

Image

I had to make two of these pieces of wood - again. Keep finding I have a piece that's almost big enough ... but the sizing is getting pretty big at this end. I'm starting to get it clear in my head, how to do everything now.
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#2667 Re: Something stirs in the Undergrowth

Post by IslandPink »

One side piece, small angle increment at half-way.
The other should follow at the weekend.
After this, it's the fibreboard and fibreglass game, been avoiding this till as late as possible
Horn1p9m_mouth1.JPG
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IslandPink
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#2668 Re: Something stirs in the Undergrowth

Post by IslandPink »

Ey up !
Is there some progress ?
Horn1p9m_mouth_assembly1.JPG
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IslandPink
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#2669 Re: Something stirs in the Undergrowth

Post by IslandPink »

Maybe, yes :
Horn1p9m_mouth_assembly2.JPG
Horn1p9m_mouth_assembly3.JPG
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IslandPink
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#2670 Re: Something stirs in the Undergrowth

Post by IslandPink »

Does anyone love the smell of polyester resin in the morning ? ... or the evening...
Horn1p9m_mouth_fibre1.JPG
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