Doc modding Marantz imperial 7

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karatestu
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Re: Doc modding Marantz imperial 7

Unread post by karatestu »

karatestu wrote: Thu Jun 10, 2021 5:19 pm The Achilles heel of this design is the stand or legs. I like the idea of three round legs (for better diffraction ofc) which are slightly splayed outwards and taper towards the floor. The tricky bit is getting them at the right angle and attaching them to the sphere.

I have had various ideas and can't decide on one atm. The one I was thinking of today at work involves one (or two) of the rings of birch ply having three little tabs which stick out at equal distance around the circumference. These can be angled to attach the legs to. I don't want a ring going all the way around as it will cause diffraction and I am trying to avoid as many sources of that as possible.
Just realised if I am turning this with a lathe then I can't leave any tabs sticking out :roll: What a numpty. They will have to be attached afterwards if I go with that idea.

I did think about wall mounts and I keep going back to that idea. My walls are brick so it could be done. I think it might be good to take the suspended floor in my room out of the equation. If hollow the arm could conceal the speaker cables. Hey presto, magic floating speakers :lol: Hard to faff with positioning though unless the bracket and arm are adjustable :think:
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Re: Doc modding Marantz imperial 7

Unread post by Ithilstone »

karatestu wrote: Thu Jun 10, 2021 6:48 pm

I did think about wall mounts and I keep going back to that idea. My walls are brick so it could be done. I think it might be good to take the suspended floor in my room out of the equation. If hollow the arm could conceal the speaker cables. Hey presto, magic floating speakers :lol: Hard to faff with positioning though unless the bracket and arm are adjustable :think:
U can use voice operated speaker stands ( aka kids) to get a very good idea about positioning :mrgreen: :mrgreen: :mrgreen:
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karatestu (Thu Jun 10, 2021 7:59 pm) • Geoff.R.G (Thu Jun 10, 2021 8:44 pm) • CycleCoach (Fri Jun 11, 2021 12:40 am)
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Re: Doc modding Marantz imperial 7

Unread post by karatestu »

Copy and paste from the website of a manufacturer of spherical speakers. I know you should not believe everything you read on a manufacturers site - marketing bullshit and exaggeration is the order of the day but anyway...........


"The Spherical Revolution

The design challenge was to design an enclosure which would at least equal that of his monstrous component system. The search was on for an inert, rigid enclosure which was lighter and more cost effective than the cabinets Gallo had been using up until that point.

“The problem was coming up with an equally inert enclosure. It had to be either very, very massive or incredibly rigid. It could not have any parallel walls and must minimise diffraction” It was at this point that Gallo looked towards the concept of using spherical enclosures.

The Sphere was found to have the best characteristics in terms of reducing internal diffractions, and was also, coincidentally, the strongest structure known. Unlike box cabinet speakers, the less mass the sphere had, the better it performed.

“Ironically enough, the 1.5 pound 12″ diameter sphere that was used in the Nucleus blew away the 300-pound monolith in terms of transparency and lack of cabinet coloration“. One thing was clear – the future was spherical"


Some interesting comments in that ( if they are true). Spheres are strong because of their shape so won't flex as much as cubes or cuboid. As well as minimising external diffraction the site mentions no parallel walls and a reduction in internal diffraction.

Probably the most interesting bit is that they thought a lightweight sphere outperformed a heavy one :grin: Maybe a thin walled lightweight acrylic sphere would be better sonically .
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Re: Doc modding Marantz imperial 7

Unread post by karatestu »

From a TNT review of an Elipson 30cm spherical speaker with 6.5" front firing coaxial

" A spherical enclosure prevents internal resonances and is strong and resistant to vibration. It also is the perfect shape for preventing reflections caused by the sharp edges of more traditional cabinets. And a concentric driver may look good, it also minimises phase errors and gives a very even distributions of the sound in all directions, certainly in combination with the spherical shape.

You would expect spherical and concentric speakers to throw a great soundstage, and that's certainly what you get, provided you have removed those grilles. The sound is open and completely disconnected from the speakers, with wonderful width and depth and excellent focus. It also is completely natural and unforced, all with spatial reproduction bordering on full 3D. With good life recordings the illusion is complete and the little Elipsons have no trouble transporting you to the recording venue. Just close your eyes and you're there.z"
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Re: Doc modding Marantz imperial 7

Unread post by karatestu »

Round is the most natural form for sound :grin:

More bigging up for spherical speakers

https://mo-sound.com/en/ball-speaker/ ... peaker/
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Re: Doc modding Marantz imperial 7

Unread post by Geoff.R.G »

karatestu wrote: Sat Jun 12, 2021 6:21 pm Copy and paste from the website of a manufacturer of spherical speakers. I know you should not believe everything you read on a manufacturers site - marketing bullshit and exaggeration is the order of the day but anyway...........


"The Spherical Revolution

The design challenge was to design an enclosure which would at least equal that of his monstrous component system. The search was on for an inert, rigid enclosure which was lighter and more cost effective than the cabinets Gallo had been using up until that point.

“The problem was coming up with an equally inert enclosure. It had to be either very, very massive or incredibly rigid. It could not have any parallel walls and must minimise diffraction” It was at this point that Gallo looked towards the concept of using spherical enclosures.

The Sphere was found to have the best characteristics in terms of reducing internal diffractions, and was also, coincidentally, the strongest structure known. Unlike box cabinet speakers, the less mass the sphere had, the better it performed.

“Ironically enough, the 1.5 pound 12″ diameter sphere that was used in the Nucleus blew away the 300-pound monolith in terms of transparency and lack of cabinet coloration“. One thing was clear – the future was spherical"


Some interesting comments in that ( if they are true). Spheres are strong because of their shape so won't flex as much as cubes or cuboid. As well as minimising external diffraction the site mentions no parallel walls and a reduction in internal diffraction.

Probably the most interesting bit is that they thought a lightweight sphere outperformed a heavy one :grin: Maybe a thin walled lightweight acrylic sphere would be better sonically .
OK then, a monocoque structure is extremely strong: the most common such structure is an egg shell, very light, very strong but also fragile. There are few true monocoque structures, the egg, the rear fuselage of the DH Mosquito and by now some made from Carbon fibre. Many structures, most aeroplanes for example, are semi-monocoque because they have internal strengthening. I am assuming that the speaker cabinet referred to above is a monocoque because internal structure would cause reflections etc.

I can see a problem with a lighter structure; drop it, hit it or have it hit an edge and it is destroyed. Remember Humpty Dumpty!

For the rest, you'll have to find a way to make one and experiment.

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Re: Doc modding Marantz imperial 7

Unread post by CycleCoach »

Geoff.R.G wrote: Sat Jun 12, 2021 6:55 pm
karatestu wrote: Sat Jun 12, 2021 6:21 pm Copy and paste from the website of a manufacturer of spherical speakers. I know you should not believe everything you read on a manufacturers site - marketing bullshit and exaggeration is the order of the day but anyway...........


"The Spherical Revolution

The design challenge was to design an enclosure which would at least equal that of his monstrous component system. The search was on for an inert, rigid enclosure which was lighter and more cost effective than the cabinets Gallo had been using up until that point.

“The problem was coming up with an equally inert enclosure. It had to be either very, very massive or incredibly rigid. It could not have any parallel walls and must minimise diffraction” It was at this point that Gallo looked towards the concept of using spherical enclosures.

The Sphere was found to have the best characteristics in terms of reducing internal diffractions, and was also, coincidentally, the strongest structure known. Unlike box cabinet speakers, the less mass the sphere had, the better it performed.

“Ironically enough, the 1.5 pound 12″ diameter sphere that was used in the Nucleus blew away the 300-pound monolith in terms of transparency and lack of cabinet coloration“. One thing was clear – the future was spherical"


Some interesting comments in that ( if they are true). Spheres are strong because of their shape so won't flex as much as cubes or cuboid. As well as minimising external diffraction the site mentions no parallel walls and a reduction in internal diffraction.

Probably the most interesting bit is that they thought a lightweight sphere outperformed a heavy one :grin: Maybe a thin walled lightweight acrylic sphere would be better sonically .
OK then, a monocoque structure is extremely strong: the most common such structure is an egg shell, very light, very strong but also fragile. There are few true monocoque structures, the egg, the rear fuselage of the DH Mosquito and by now some made from Carbon fibre. Many structures, most aeroplanes for example, are semi-monocoque because they have internal strengthening. I am assuming that the speaker cabinet referred to above is a monocoque because internal structure would cause reflections etc.

I can see a problem with a lighter structure; drop it, hit it or have it hit an edge and it is destroyed. Remember Humpty Dumpty!

For the rest, you'll have to find a way to make one and experiment.
I'd have to disagree about the fragility. That shape is literally the strongest possible using a minute amount of material. (Try squeezing an egg between two fingers (as hard as you like) to see what I mean.) The problem you're describing is with a point loading due to impact, and believe me. very little would survive that, no matter what shape it is.
For the purpose Stu is suggesting, I think a sphere will be fine. Strong is the opposite of fragile in my book.
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Re: Doc modding Marantz imperial 7

Unread post by Fretless »

There are 30cm stainless steel spheres available via AliExpress.

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Re: Doc modding Marantz imperial 7

Unread post by Latteman »

Analogue Source -
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Re: Doc modding Marantz imperial 7

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Anti-pregnacy yoga ball!

Whatever will they think of next?

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