Something stirs in the Undergrowth

Dedicated to those large boxes at one end of the room
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Ray P
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Re: Something stirs in the Undergrowth

Post by Ray P » Sat Sep 14, 2019 2:03 pm

izzy wizzy wrote:
Sat Sep 14, 2019 10:47 am
Worth every cent. I'm in the queue card poised.
Not suggesting otherwise and I would like a copy myself - may have found my Christmas present. :santa:

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IslandPink
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Re: Something stirs in the Undergrowth

Post by IslandPink » Sat Sep 14, 2019 2:53 pm

The contents list is amazing - and over 1000 pages.
Ray P wrote:
Sat Sep 14, 2019 6:32 am
I thought it had started to go wrong with the edge nearest the router base as it doesn't look smooth?
Looking forward to hearing about your impressions with this project.
No, that front edge had not been done yet, it was just rough-cut.
ps. The internal cross-panels allow roller cutting of the top. front and back.
The remedial piece of pine I put in has now been sanded down ready for a final router cut when assembled - but will need something like wood filler or bleach to hide the rather obvious coarse grain which is at an angle to the edge.

Struggling with a cold today, it came on suddenly yesterday evening.
I have enough small jobs to do today to leave the 'closing ceremony' for tomorrow.
"The bass is the king of the instruments - it has no known natural predator" (Wobble)

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Ray P
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Re: Something stirs in the Undergrowth

Post by Ray P » Sat Sep 14, 2019 3:30 pm

IslandPink wrote:
Sat Sep 14, 2019 2:53 pm
The remedial piece of pine I put in has now been sanded down ready for a final router cut when assembled - but will need something like wood filler or bleach to hide the rather obvious coarse grain which is at an angle to the edge.
You could patch in a small piece of the ply - done carefully and with the grain aligned the repair will all but disappear - you only need to cut a recess just less than the thickness of the the outer veneer of the ply, slice a piece off, glue on and sand flush. Maybe these will help?





But for what you need to do I think a simple round punch will suffice?

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IslandPink
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Re: Something stirs in the Undergrowth

Post by IslandPink » Sun Sep 15, 2019 9:49 pm

Good info, saved for ref. Bit much to do in the context of this experiment though.
Today, struggling with a cold, managed to get this done and playing :
Double_Final1.JPG
Apologies for crappy picture, I was shaking with fatigue when I took this -
Double_playing.JPG
Need time to comment, the rear driver is new and needs running-in.
"The bass is the king of the instruments - it has no known natural predator" (Wobble)

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Ali Tait
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Re: Something stirs in the Undergrowth

Post by Ali Tait » Mon Sep 16, 2019 8:26 am

Top work Mark!
Image[/img]

steve s
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Re: Something stirs in the Undergrowth

Post by steve s » Mon Sep 16, 2019 10:00 am

They look great mark...
They appear a diversion compared to to the baffles but look really good.
The tube manual is quite like a telephone book. The number of it perfect. It is useful to make it possible to speak with a girl. But we can't see her beautiful face from the telephone number

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IslandPink
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Re: Something stirs in the Undergrowth

Post by IslandPink » Mon Sep 16, 2019 3:17 pm

steve s wrote:
Mon Sep 16, 2019 10:00 am
They look great mark...
They ? :D
It . Thanks.
Actually not finished cosmetically, need some final trimming when I get a new router bit, and all the ( 16 ) holes on the 2nd side panel plugging with dowel as I've done on the first side. The some varnish or wax.
steve s wrote:
Mon Sep 16, 2019 10:00 am
They appear a diversion compared to the baffles but look really good.
Well sort-of, but this is the continuation of 'Plan A', to horn load as much of the frequency range as possible.
Getting something good from upper mids to upper bass is the target.

So far it's interesting, after a few hours workout of the drivers. There is some horn-loaded sound, the bass is quite punchy and there's content down lowish, to about 50Hz certainly. There isn't the richness of tone I wanted in the male vocals though.
It doesn't sound coloured in a horn way - so the 'interlacing' of the two horns is doing something good.
The 126eN has its limitations higher up - I'm just mentally blocking that out.
I'm pretty sure I can hear the delay of the longer horn - which is nearly 3m. Hmmm...
Have been using the TDA7297 chip amp, might try the 300B amp soon, though it's rolled-off for use on the OBs.

One thing I haven't done yet is put some light stuffing ( wool ) in the throats of the two horns as Horst recommends. This ought to slightly improve the midrange tone - hopefully without reducing bass output too much....
"The bass is the king of the instruments - it has no known natural predator" (Wobble)

SimonC
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Re: Something stirs in the Undergrowth

Post by SimonC » Tue Sep 17, 2019 8:55 am

IslandPink wrote:
Fri Sep 13, 2019 10:55 pm
Just waiting to offer my card details -
http://www.hornspeakersystems.info/
http://www.hornspeakersystems.info/images/pdf/TOC.pdf
YES :D :D :D
Just skimmed the TOC and its looks like it looks like a greatest hits tour for horn design history, theory and application. Bjorns white papers on horn design have teased little snippets of the work done in the 1930/40's and its going to be good to have this all together in one place and see how it ties into his work. I think I may also be dusting off my card...

Simon C

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IslandPink
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Re: Something stirs in the Undergrowth

Post by IslandPink » Wed Sep 18, 2019 11:28 pm

Light stuffing of long-haired wool inside throats around both driver input, this evening.
Seems to have had beneficial effect. Very good.
Delay in horn output is more clear now though. Not great on rhythm-critical stuff.
"The bass is the king of the instruments - it has no known natural predator" (Wobble)

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IslandPink
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Re: Something stirs in the Undergrowth

Post by IslandPink » Sat Sep 21, 2019 9:07 pm

More infamy :
Router_roller2.JPG
I think it's trying to tell me I need a better router - this cheap one is battering the hell out of the rollers due to the poor spindle /bearings.
"The bass is the king of the instruments - it has no known natural predator" (Wobble)

izzy wizzy
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Re: Something stirs in the Undergrowth

Post by izzy wizzy » Sat Sep 21, 2019 9:29 pm

I've bought many cheap routers - 3 in all for work; kitchen fitting mainly. Then I bought Makita this year to make a set of Edwardian stairs as I didn't trust the cheap stuff for that. Bloody hell, there's a huge difference not only in power but smoothness and shear cutting ability even with the budget Trend cutters. So accurate too and easy to use as well. The other 3 routers added up to more than the Makita so sometimes cheap is not always the cheapest in the long run even when not using these things often. I don't know why this was the only machine I went budget on when everything else is mostly Makita, some Dewalt and Bosch which are also decent.

Cheers,
Stephen

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IslandPink
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Re: Something stirs in the Undergrowth

Post by IslandPink » Sat Sep 28, 2019 2:59 pm

Did more listening and running-in after some cosmetic stuff.
A few more observations . I feel the overall concept is a pretty good package, it's successful in some ways, not all.
With some wool in place in the horn throats, the upper midrange is quite nice, at least as far as the 126e can provide.
The lower part of the midrange on male vocals is OK but not as good as I hoped. Doesn't have the tone or 'snap' I had from the folded horn at one stage. Maybe the phase disjoint from the front driver to the shorter horn mouth in the 150-300Hz region is not helping.
The bass on its own is well-shaped dynamically and doesn't seem 'lumpy' or coloured - the twin horns and their carefully chosen lengths seem to be doing a good job.
The low bass is actually pretty good, despite the roll off on the sims - room gain is enough, if the rear of the horn is placed about a foot from a wall ( or bay window in my case ) .
The bass delay is audible. If you've been listening to OB or sealed boxes, it's fairly obvious. I had hoped the staged delay from front output to horn 1 to horn 2 might blend things in a more convincing way, but it doesn't .

So... for the horn solution ( Plan 'A' ) , it's not exactly back to the drawing board - it has helped clarify what's needed and what the limits are. I think a delay of something like 3ms would be OK ( the Kornett has 8 ms ) . I think the region down to at least 80Hz needs to be properly horn loaded - ie. with a decent mouth size - unlike the horn/TL hybrid loading from the small mouths that Horst has. The phase needs to be flatter to get the tone and dynamic snap.
I have done a brief sim of a 2.5m horn using the Fostex 208Ez and it looks good , probably used as an 'L' horn.
Just needs a bit of a 3D sim on the mouth shape and height - Simon C ? :D
"The bass is the king of the instruments - it has no known natural predator" (Wobble)

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IslandPink
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Re: Something stirs in the Undergrowth

Post by IslandPink » Sat Oct 05, 2019 7:55 pm

Info here for SimonC -
Front room looks like this , if you want to estimate room modes . Dims in metres.
Width of room doesn't quite work out with sections of bay added together, at least on the assumption the side windows are a 45deg to the middle one - maybe they are not ?
Derwendeg_frontroom.png
"The bass is the king of the instruments - it has no known natural predator" (Wobble)

SimonC
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Re: Something stirs in the Undergrowth

Post by SimonC » Mon Oct 07, 2019 9:09 am

IslandPink wrote:
Sat Oct 05, 2019 7:55 pm
Info here for SimonC -
Front room looks like this , if you want to estimate room modes . Dims in metres.
Width of room doesn't quite work out with sections of bay added together, at least on the assumption the side windows are a 45deg to the middle one - maybe they are not ?

Derwendeg_frontroom.png
Thats more than enough to get it underway, a few degrees or cm out either way don't make a lot of difference at the wavelengths we are looking at...

Simon C

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IslandPink
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Re: Something stirs in the Undergrowth

Post by IslandPink » Wed Oct 09, 2019 7:16 pm

Cheers.
meanwhile ... yummy previews :
http://www.hornspeakersystems.info/inde ... story-part
http://www.hornspeakersystems.info/inde ... orn-theory
They seem quite proud of having made something that looks and feels like a classic textbook and goes against the grain of catering for the modern short attention span.
"The bass is the king of the instruments - it has no known natural predator" (Wobble)

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