Something stirs in the Undergrowth

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al newall
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Postby al newall » Fri May 13, 2011 6:24 pm

Dave the bass wrote:
al newall wrote:If thats what it takes to get close to real music.
I may as well give up now and take up knitting or summat.


Move away from the knitting needles :-)

If you REALLY want to get closer to music our-Al there's none-more-closer than actually playing it yerself!

Buy an acoustic guitar and learn a few songs.


DTB


I'm full of admiration for those who play instruments. Sadly i,m not amongst them.

Been there, bought guitars and tried it, but my hands are better suited to manual labour than fiddly strings. Even the bass was a struggle.
Much to learn there is.

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Mike H
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Postby Mike H » Fri May 13, 2011 6:24 pm

ed wrote:contentious ?, cor, we do contentious..

Image

really good example imo is robert plant/alyson krauss 'raising sand'..some similar instruments so close together that some systems can't delimit them and the result is a bit mushy while other systems seperate them....reading between the lines...

Thanks for reminding me I've got that, will have to play it again as it's been a while ~ lot of solder under the bridge since...

Well, some....

About this much

Image


 
 
"Nor yet is it still..."

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IslandPink
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Recording

Postby IslandPink » Sun May 15, 2011 3:59 pm

andrew Ivimey wrote:How I wish Jimi Hendrix's work had been better recorded originally (bit like how the SACD of DSOTM doesn't really sound any better than the CD / or vinyl)


'Band of Gypsies' is an excellent recording , I think . Very musical, spacious, dynamic .

By the way, anyone an expert on spokeshaving ?
I'm having a right old struggle finishing the (concave) curves on these pieces of 18mm ply for the horn sides . Tried a flat-face spokeshave, and a convex-faced spokeshave ( just bought ) . Can't find a setting between 'not cutting' and 'juddering horribly' . Can't think of another way of doing it either, as the curve is compound .

MJ
"The moon was a stone's throw"

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Toppsy
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Postby Toppsy » Sun May 15, 2011 4:07 pm

If you have a router then you just need a straight cutting bit with a template roller follower. i.e the roller is at the top. You can then simply make a template from 6mm MDF. It's what I do.

Perfect copies each time and perfect 90 deg cuts along the curve.

I find it best to nail the template to the bass ply using some 15mm panel pins. The small holes can be filled with any propriortory wood filler.

Simples Hey :wink:

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IslandPink
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Postby IslandPink » Sun May 15, 2011 5:43 pm

Toppsy wrote:Perfect copies each time and perfect 90 deg cuts along the curve.
Simples Hey :wink:


Thanks for the advice Colin , but I'm ahead of you :) unfortunately it's not 'simples' !
A cut 90 deg to the faces is precisely NOT what I need :cry:
Because of the way I want to lay the bendy-MDF flush onto the edges, and the fact these side-pieces diverge by about 13.4 degrees to the axis ( each ) ie. 26.8 degrees included angle, the template has been laid onto each side of the ply and shifted by 4.3mm on one side relative to the other . This is the tan of 13.42 degrees :!:
Hence when finished, the curve , as well as having the correct expanding profile, also has an angle to the faces that goes from about 0 deg at the throat, to about 11 deg at the mouth end. It's a funny compound curve. Hence the only two ways I could think of doing it were :
(i) CNC router coming down vertically with the wood blocked-up at 13.4 degrees
(ii) mark curve on both sides , displaced, and spokeshave down to the line on both sides.

No. (ii) is cheaper !
Luckily - STOP PRESS - I have been getting on OK just now - I found the ply is somewhat directional in how it cuts, and have been able to get along well with the flat-based spokeshave pulling it the other way, and have finished another curve this afternoon . Looks like I have the 'knack' now.

Cheers
MJ
"The moon was a stone's throw"

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IslandPink
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Postby IslandPink » Sat May 21, 2011 7:56 pm

Damn Damn Damn Damn Damn :!:
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shane
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Postby shane » Sat May 21, 2011 8:01 pm

Oh dear.



Tell Daddy...

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IslandPink
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Postby IslandPink » Sat May 21, 2011 9:07 pm

I feel like that Greek bloke rolling the stone up to the top of the hill then seeing it roll down again and having to start again .

Ok, so I've finished the two sides and was just working on measuring the placement of the wedge-piece that's going to hold the two sides in correct place while I fit the bendy MDF onto the top and bottom .
Then ...you know how sometimes you have a discrepancy in some measurements, then you get confused and suddenly realise something more fundamental and horrible has gone wrong ?

So basically, when I made the template for the sides, the centre-line and 'X-axis' I used was the axial length of the horn . Unfortunately this is the dimension along the centre-line - in air. I should have used the 'side length'. which longer by a factor of (1/cos 13.42) .
So, my horn will be 2.8% too short :(

Ok, it's not bad enough to make the horn useless, but I will have to make another TWO horns now, in the long run . This one will be not quite right, and not go quite as low as intended .

I suppose if it was easy, everyone would be doing it :roll:
Attached the construction data, for those who are curious.
ILPS
Attachments
tra_1.txt
(6.63 KiB) Downloaded 96 times
"The moon was a stone's throw"

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Nick
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Postby Nick » Sat May 21, 2011 9:39 pm

Bummer. But if its any help, I bet you do a better job next time anyway. When writing software, its normal to have at least two goes.
it's an interesting fact that most people have more than the average number of arms.

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IslandPink
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Sim

Postby IslandPink » Sun May 22, 2011 11:05 am

Actually I've modelled the result this morning .
Looks like I'll get a 122.4 Hz ( was 120 ) Tractrix with a mouth area of 3424 sq-cm ( was 3500 ) . It looks pretty good actually - plenty good enough to finish off 'Nice' and do full evaluation before building the 2nd one.
Phew ! - motivated again :bounce:

See attached
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Horn_1st_error.JPG
"The moon was a stone's throw"

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IslandPink
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More

Postby IslandPink » Sun May 22, 2011 12:33 pm

Oh, and by the way I blame Kate Middleton for the error .

Meanwhile, progress, see attached.
(i) Close-up of one end of horn profile showing rounding and (not so obvious) slant of curved edge from one side to the other to allow flush-fitting of the curved MDF .
(ii) Two sides held by temporary wedge ready for fitting of curvy sides .
Attachments
KIF_0123.JPG
KIF_0122.JPG
"The moon was a stone's throw"

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Paul Barker
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Postby Paul Barker » Sun May 22, 2011 7:12 pm

Are you making good plans etc so anyone can follow your design? You never know.

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IslandPink
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Vines

Postby IslandPink » Sun May 22, 2011 7:44 pm

Attached, "Still life with horn and vines 2011"

Hi Paul -
All info for these will be available if anybody wants to copy . Really the useful things for someone else will be :
1. Hornresp model
2. Hornresp output data table for the chosen rectangular form
3. The cutting template for the side pieces ( I will save this )
and
4. the wedge-piece for joining the sides, and instructions for where to position it relative to the throat end .

If someone just wants to make it, not try to understand all the theory, then these will save them a whole load of time.

MJ
Attachments
KIF_0124.JPG
"The moon was a stone's throw"

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Mike H
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Re: More

Postby Mike H » Sun May 22, 2011 10:36 pm

IslandPink wrote:Oh, and by the way I blame Kate Middleton for the error .

As good a reason as any Image


Silly question time ~ would it not be possible to graft on extra "extension bits" so it's the right lengft, a bodge I know so am I talking out of my orifice


 
 

"Nor yet is it still..."

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IslandPink
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Postby IslandPink » Mon May 23, 2011 6:00 pm

Not a silly question , Mike, but there are some problems -
One - it's going to be hard to make that 'nice' or 'neat' .
Two - it will still be a '122.4 Hz' expansion, because the side-panels have already been cut to this curve which expands a bit too quick - so extending the mouth end will not extend the bottom-end response at all - you'd just be making a 122.4Hz horn with a bigger mouth, which means it would have a tadge less ripple on the response ( which is pretty smooth anyway ).

As I said to Nick on e-mail today - it's within the uncertainty of my last few ummings and arrrings about where to finalise the design, a few weeks ago, anyway .

Thank god, because I don't want to repeat making that template in a hurry , it took me best part of two days of very careful work .
"The moon was a stone's throw"


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