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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#2176 Re: Something stirs in the Undergrowth

Post by IslandPink »

To be honest the panels I have up there at the moment have some dust and some marks on, but I haven't dared clean them yet, just need to do a bit of checking on how not to damage the finish - eg. what type of cleaner and cloth to use. I'm sure isopropyl will be OK but maybe one of the normal window cleaners would be OK. I need to test . I should buy a new duster for this so it's clean, don't want any other dust or debris in there , I'm sure I'll get fine scratches in an instant if I'm at all lax in how I clean it.

I'm not sure, Simon - anything hand-held could get out of control very rapidly. I think the router will be OK for thin cuts - I have already got nice results on the lower panel front edges using a rounding edge cutter ( with roller ) , just left a matt finish, nice clean cut.
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#2177 Re: Something stirs in the Undergrowth

Post by simon »

I couldn't work out how you are going to control the router - any cutting template would be a challenge to make 0.4mm larger. Perhaps I've misunderstood.
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IslandPink
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#2178 Re: Something stirs in the Undergrowth

Post by IslandPink »

It's just an edge I need, for a couple of inches. Get a good bit of 12 or 18mm ply with a clean straight edge and lay it on top of the Perspex with its edge just shy of the edge of the Perspex slot side. Then use a 12mm straight cutter with a roller at the top , to guide from the wood edge.
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Toppsy
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#2179 Re: Something stirs in the Undergrowth

Post by Toppsy »

Are you aware that TREND make a specific range of router cutter bits designed for machining Acrylic?
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#2180 Re: Something stirs in the Undergrowth

Post by simon »

Ah! The penny drops. Don't know why but I thought it was a cicular hole. Must pay more attention!
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IslandPink
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#2181 Re: Something stirs in the Undergrowth

Post by IslandPink »

Toppsy wrote: Wed May 02, 2018 12:17 pm Are you aware that TREND make a specific range of router cutter bits designed for machining Acrylic?
No Colin this is very interesting, I will have a look into that.
As it is , for my trimming of 1mm off each side of the cut-outs in the upper baffle pieces today, I got a very good finish with the 12mm top-roller cutter and a speed around 60% of normal, so this job can be completed. I'll have more time tomorrow and will do the cutting and trimming of the slots in the main baffle panels.
The bit that is frustrating otherwise is how to cut anything from scratch like a slot or a circle in this material ( 20mm ) , I've done it with a jigsaw with a Bosch multi-purpose blade, but the cutting speed is less than 10mm/minute and the cut closes up behind you as the material melts and re-solidifies, so you end up going through the cut 3 or 4 times till it's open.
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#2182 Re: Something stirs in the Undergrowth

Post by IslandPink »

Can't help feeling I could have made better decisions today. I got up feeling a bit tired so instead of going out anywhere, I decided to try & finish doing at least one OB with the ribbon fitted. I spent most of the day working very slowly in increasing heat on the back porch, trying not to scratch either of these big pieces of of Perspex. Tools kept hiding from me in the kitchen. I managed somehow to scratch the upper piece to the left of where the ribbon mounts. Then I fitted the small M4 spline bushings for the lower mounting screws of the ribbon and cracked from there to the corner of the cut-out, because I'd only got 5mm and 5.6mm drills and should have had a 5.2 or a 5.4 , so the fit was really tight and I had to whack it in really hard. Anyway I got to the end of it, covered in Perspex chaff and almost fainting, around 6:30pm. Came in and fitted both pieces to the wooden sides of the OB & base. The slot on the main panel is misaligned to the slot on the upper panel by about 1mm, so the ribbon doesn't fit :roll:
Now I'll have to have to go at it again ( but not tomorrow ) .
The sun and the landscape was just as good as it gets today- should have had a leisurely drive around the lanes with a camera or two, that would have been more sensible.
Hopefully the weather will continue tomorrow and I'll have more energy.
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andrew Ivimey
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#2183 Re: Something stirs in the Undergrowth

Post by andrew Ivimey »

I'm in Malvern - fab weather, lovely walk. Tomorrow too and I've found out how to use the coffee machine so breakfast tomorrow will be pure joy.

Early this morning I went round the 18th century gate house we're staying in playing classic fm thro the ancient iPad 2 I normally use for musical notes and ideas stuff. I tried the bath, the sink, up against a flat wall, a big glass window, on the thick pile carpet, on top of a cupboard etc - huge differences to sound quality, made me think more than a little about what we're doing with drive units and boxes. I'm very impresssed with how much the IPad speaker can put out and how easy it is to improve, the sound field being so small too. Great background lissnin' but not ffrr serious stuff... nevertheless
Philosophers have only interpreted the world - the point, however, is to change it. No it isn't ... maybe we should leave it alone for a while.
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#2184 Re: Something stirs in the Undergrowth

Post by IslandPink »

Good to see someone doing some basic science there Ivimey , and I bet Malvern & environs look great this weekend. N.Wales is glorious today - did a trip over to the gallery then round via the lanes & moors back to the gaff.

About 40mins this lunchtime sorted the RH OB, some extra router trimming, then Mr. Snouty came in very useful for taking out the top chamfer right to the corners, which was a headache initially.
Baffle_tweeterslot.JPG
Baffle_tweeter_situ.JPG
Plan is to get a wedge-shaped make-up piece done by rapid-prototype , to smarten up the fit from the tweeter to the upper panel.
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IslandPink
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#2185 Re: Something stirs in the Undergrowth

Post by IslandPink »

Can't give up on horns though - some comment from Joelist re. Munich show :
"Thanks for everybody for this years Munich show!

Being a student level in audio matters, I got good audio education in
Silbatone room.

I also got to chat with some of the board members (Joe, JC, and Thorsten)

I got to listen to Living Voice big speakers with Engstrom amp.
It is beyond my comprehension how they have achieved that music sounds like
one instead of broken in pieces. Especially with that amount of drivers and
funky horns"
"Once you find out ... the Circumstances ; then you can go out"
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IslandPink
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#2186 Re: Something stirs in the Undergrowth

Post by IslandPink »

"Once you find out ... the Circumstances ; then you can go out"
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#2187 Re: Something stirs in the Undergrowth

Post by SimonC »

I'm still digesting the horn design details, a lot to take in....tractrix, exponential and hyperbolic all in the mix together :shock:
The carbon bling is very pretty though.
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#2188 Re: Something stirs in the Undergrowth

Post by IslandPink »

It actually makes a lot of sense, Simon. On the bass end you need frequency extension : so slower expansions, even if the mouth size is limited, will get you lower with less phase shift over the band. There will be ripple, on paper, but in a region where the ear is less sensitive and the room has lots of peaks and dips. The big horn will also have rolled off, more or less, by the time you get to the upper mids where the expansion type is more critical. Think of the big bass horn as being like an unfolded Dallas II with a bit more length and mouth size - it's also not fully loaded to 20Hz, it'll be horn loaded down to maybe 60Hz, then transmission line, less efficient from there to maybe 30Hz.
The driver technology looks very special , compression driver even for the bass, the upper bands have beryllium diaphragms, etc etc .
"Once you find out ... the Circumstances ; then you can go out"
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andrew Ivimey
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#2189 Re: Something stirs in the Undergrowth

Post by andrew Ivimey »

I've been watching the YouTube videos - all a bit overwhelming! My bro'in law was there with his headphones- cant help thinking the stuff is wasted on him. He loves his TVR, the headphones were just a project.

Some of that equipment/ the horns that Mark was highlighting. Amazing, fascinating but much too much for me. Love to have a listen tho.
Philosophers have only interpreted the world - the point, however, is to change it. No it isn't ... maybe we should leave it alone for a while.
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izzy wizzy
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#2190 Re: Something stirs in the Undergrowth

Post by izzy wizzy »

IslandPink wrote: Mon May 14, 2018 7:35 pm Can't give up on horns though - some comment from Joelist re. Munich show :
"Thanks for everybody for this years Munich show!

Being a student level in audio matters, I got good audio education in
Silbatone room.

I also got to chat with some of the board members (Joe, JC, and Thorsten)

I got to listen to Living Voice big speakers with Engstrom amp.
It is beyond my comprehension how they have achieved that music sounds like
one instead of broken in pieces. Especially with that amount of drivers and
funky horns"

I went to Munich this year and met JRob, jc and Bjorn Kolbrek. Apart from the silbatone room, the vox olympians were in a different league to anything there and frankly anything I've ever heard and endorse that cut from the same cloth sound. Just about everything else was incredible in how bad regular hifi sounds no matter the cost.

Cheers,

Stephen
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