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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Re: Something stirs in the Undergrowth

Post by IslandPink » Sat Jul 04, 2020 8:41 pm

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.
"Peridots and periwinkle, blue medallions Gilded galleons spilled across the ocean floor" ( Mitchell )

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Re: Something stirs in the Undergrowth

Post by JamesD » Sun Jul 05, 2020 1:19 pm

Nice to see real progress on this horn and I really hope it performs to your expectations!

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IslandPink
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Re: Something stirs in the Undergrowth

Post by IslandPink » Sun Jul 05, 2020 2:39 pm

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
"Peridots and periwinkle, blue medallions Gilded galleons spilled across the ocean floor" ( Mitchell )

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Re: Something stirs in the Undergrowth

Post by JamesD » Tue Jul 07, 2020 1:22 pm

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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Re: Something stirs in the Undergrowth

Post by IslandPink » Tue Jul 07, 2020 8:10 pm

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.
"Peridots and periwinkle, blue medallions Gilded galleons spilled across the ocean floor" ( Mitchell )

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IslandPink
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Re: Something stirs in the Undergrowth

Post by IslandPink » Tue Jul 07, 2020 9:49 pm

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.
"Peridots and periwinkle, blue medallions Gilded galleons spilled across the ocean floor" ( Mitchell )

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IslandPink
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Re: Something stirs in the Undergrowth

Post by IslandPink » Wed Jul 08, 2020 8:01 pm

This evening I had to make another piece of wood.
"Peridots and periwinkle, blue medallions Gilded galleons spilled across the ocean floor" ( Mitchell )

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Re: Something stirs in the Undergrowth

Post by Ray P » Wed Jul 08, 2020 9:36 pm

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:

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IslandPink
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Re: Something stirs in the Undergrowth

Post by IslandPink » Thu Jul 09, 2020 12:17 am

No - good guess - part of my recycling ethic - one piece of 18mm birch ply, almost big enough .. needed an offcut to make it sufficient !
"Peridots and periwinkle, blue medallions Gilded galleons spilled across the ocean floor" ( Mitchell )

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IslandPink
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Re: Something stirs in the Undergrowth

Post by IslandPink » Mon Jul 20, 2020 12:23 pm

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
"Peridots and periwinkle, blue medallions Gilded galleons spilled across the ocean floor" ( Mitchell )

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IslandPink
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Re: Something stirs in the Undergrowth

Post by IslandPink » Sat Jul 25, 2020 7:35 pm

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.
"Peridots and periwinkle, blue medallions Gilded galleons spilled across the ocean floor" ( Mitchell )

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IslandPink
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Re: Something stirs in the Undergrowth

Post by IslandPink » Tue Aug 04, 2020 2:09 pm

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
"Peridots and periwinkle, blue medallions Gilded galleons spilled across the ocean floor" ( Mitchell )

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