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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#2206 Re: Something stirs in the Undergrowth

Post by IslandPink »

Bit of throat surgery :
( I have to open up this area enough to block and seal the existing 9 x 10cm entry hole , before I start adding pieces to extend the length )
Nice to be back in the saddlle and have the opportunity to use a tenon saw, a rip saw, a router, a jigsaw, two chisels, a drill and two large screwdrivers in the space of 3 hours. Plenty more fun to follow.
Throat_surgery.JPG
"Once you find out ... the Circumstances ; then you can go out"
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IslandPink
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#2207 Re: Something stirs in the Undergrowth

Post by IslandPink »

Had a pretty productive weekend. This was situation at lunchtime, quite a bit more was done later today.
Shot here shows the old driver hole blocked-off and filled, and one new piece of wood in place - a side panel for the new extension - it took a barely finite amount of time to get this piece made, fitted to the existing parts and angled correctly when screwed/glued down. The rest should be ( is ) more straightforward.
HornMk5_ii.JPG
Here the other parts. I also (not shown ) made and fitted the small end piece that closes the horn path at the small end -
HornMk5_parts.JPG
"Once you find out ... the Circumstances ; then you can go out"
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IslandPink
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#2208 Re: Something stirs in the Undergrowth

Post by IslandPink »

I should really bring home some night-vision goggles to extend the working day :
HornMk5_iii.JPG
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IslandPink
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#2209 Re: Something stirs in the Undergrowth

Post by IslandPink »

More work this evening - top panel fitting holes drilled and temp. fitting, followed by edging and rounding of panel ( to side panels ) with router. Then I removed and sanded smooth remaining internal filler areas and varnished the whole interior of the new section, to bind the surface wood together.
Definitely on course for a Friday listening session, now.

ps. Haven't heard anybody commenting on the build as 'shoddy' yet ? :)
"Once you find out ... the Circumstances ; then you can go out"
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Dave the bass
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#2210 Re: Something stirs in the Undergrowth

Post by Dave the bass »

Ah, apologies.

Tera-shod!
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IslandPink
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#2211 Re: Something stirs in the Undergrowth

Post by IslandPink »

In the context of this forum, I don't think 'shoddy' is really the correct word. Maybe 'sleek !' or something. I am really quite proud of how monstrous this experiment has become !
A14ADR.jpg
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Dave the bass
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#2212 Re: Something stirs in the Undergrowth

Post by Dave the bass »

Image
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IslandPink
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#2213 Re: Something stirs in the Undergrowth

Post by IslandPink »

Chortle !

On course for final assembly and then first test this evening :bounce:
Meanwhile, for SimonC's benefit , some data here.
This Hornresp listing shows the current build, as three exponential sections. The new bit is the S1 to S2 section, from 72 to 90 square cm, in 55cm length.
The existing 1.65 or 1.7m horn is just the S2 to S4 sections (the two exponential sections with different Hz expansions are a pretty good approximation to the 55Hz exponential as originally designed ).
There's a fairly large back-volume shown on this model, but it doesn't do much for the loading, and in practice, I'm hoping it isn't needed, although if the concept works there will be some damping material required to curb the back output.
PMVO_iv_220cm.png
PMVO_iv_220cm_pic.png
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IslandPink
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#2214 Re: Something stirs in the Undergrowth

Post by IslandPink »

Just about to start listening.
Here are a few shots to set the scene :

Driver fitting collar and phase plug fitted to new throat of horn. There's a smooth blend into the 9 x 8cm starting aperture.
HornMk5_vii.JPG
Fostex FE208Esigma fitted - & throat end (new part ) from the side.
HornMk5_v.JPG
Side view - the thing is so huge I can't get it all in the picture.
HornMk5_vii.JPG
Attachments
HornMk5_v.JPG
HornMk5_iv.JPG
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IslandPink
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#2215 Re: Something stirs in the Undergrowth

Post by IslandPink »

I have no idea what was going on with the picture-inserting routine there - couldn't get it right. Hopefully you can try & match the captions to the pictures. Here's the last one that wouldn't load :
HornMk5_vi.JPG
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IslandPink
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#2216 Re: Something stirs in the Undergrowth

Post by IslandPink »

Well...first listening tests show that ... it's not that good :roll:
It's a small increment on, vs. the last build, but it hasn't done the 'thing' I wanted in the upper bass. It sounds like it's properly loaded the lower mids, in fact the mids overall sound really good, but it's not quite got the 'snap' and 'precision of tone' that I was after.
I've been mulling-over it for an hour or two and the only thing I can think of vs. the back horns like the Fostex and Dallas II is that they have a pretty confined path ( within 400 sq cm ) out to 1.65 or 1.9m length, whereas this one , despite the narrow start , is still 400 sq.cm at 1.35m. Maybe this is significant in terms of loading and hence phase flatness, under 150Hz.

Time for a holiday !
"Once you find out ... the Circumstances ; then you can go out"
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Ali Tait
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#2217 Re: Something stirs in the Undergrowth

Post by Ali Tait »

Don’t know if you’ve seen this Mark, thought it might be of interest-

http://zero-distortion.org/diy-horns/
steve s
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#2218 Re: Something stirs in the Undergrowth

Post by steve s »

Ali Tait wrote: Tue Oct 16, 2018 9:06 am Don’t know if you’ve seen this Mark, thought it might be of interest-

http://zero-distortion.org/diy-horns/
Most of guys system was usually at the wam show few years ago.
To be honest most people were very impressed...
I thought it was good, but even if I had room I could hear what the horns did to the bass and the solid state amps driving it seemed to thicken it up.

It's also a great title... zero distortion then talk about horns..
or speakers for that matter
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
vinylnvalves
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#2219 Re: Something stirs in the Undergrowth

Post by vinylnvalves »

I remember Guys horns too, they were very dry for my taste, good for classical/operatic music. From what I remember they didn’t go too low. Now for bottom end it was Pete’s ( I should coco) system , that came a couple of years later, with the wall of bass drivers which had more realism. I am probably going to get abuse for saying this... I don’t think bass horns will ever work in a domestic situation, unless you live in a mansion and have the room. As power is cheap nowadays a wall of drivers similar to the BD orphean can get you along way to the low distortion a horn brings, maybe without the colouration.
My bass horn attempts.. have kept our wood burning stove going for years.. birch ply burns well :)
vinylnvalves
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#2220 Re: Something stirs in the Undergrowth

Post by vinylnvalves »

Got the wrong BD speaker it’s the Orelino...https://www.pinterest.co.uk/pin/418060777887401688/
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