Doc modding Marantz imperial 7

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karatestu
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Re: Doc modding Marantz imperial 7

Unread post by karatestu »

antonio66 wrote: Wed Jan 26, 2022 2:15 am That's the way to go, I don't like the drainage pipe idea, so if you can remove the top piece where it straightens up it would look great, as to the bottom doing the same, i'd probably go with that as well.
Hello Dave.

The drainage pipe was never going to be used it was there so the sphere could clear the bit that sticks up for a quick mock up without hacking the stool. I don't like the half stool idea idea much anyway so it was a bit of a waste of time.

The full stool version will be much more elegant and seductive :grin: I agree that the two bits where it straightens up need to be removed. I will just remove the bottom one and the stand's curve will flow nicely into the wooden base. I am not sure I like the wooden base with this version but it will be needed if I am going to use a long threaded rod to put all these parts under compression (to hold them together).

For the top where the steel sphere will sit in the stool stand I need to chop about two inches off the top so the two fit snugly and there is no gap.

Like this

Image
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Re: Doc modding Marantz imperial 7

Unread post by karatestu »

COPIED FROM THE ISOLATION THREAD

Well I couldn't leave the idea alone :roll:

I suffer with suspended wooden floors both at home in my living room and at the farm where I do most of my diy bodgeneering. I was happy to take the concept on board and try to come to my own conclusions. The prospect of very low or even no vibration being transmitted to the floor is very alluring.

To that end I hunted around for my kid's old bikes. Found a couple of 11" inner tubes which are too small really. Then found some 16" tubes that seem to be just the job.

Tried them under one of my sphere mock ups with hourglass stool stand. I can't listen to the effect on these as they are not ready but I wanted to see what it looked like and watch it wobbling with some weight on. The inner tubes are slightly too big for the 35cm wooden circles I have but it turned out very interesting. The inner tube turns into a kind of black bumper all the way around as half of the tube sticks out whilst the other half is under the wood.

Image

Image
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Re: Doc modding Marantz imperial 7

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COPIED

I even made a video of it wobbling back and forth :lol: Forget to edit out my heavy breathing :oops:

[bbvideo] [/bbvideo]

You can see it wobbles very slowly which is representative of the resonant frequency I think. Slower the better. There is not that much air in that inner tube but I might see if I can go lower in pressure.
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Re: Doc modding Marantz imperial 7

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So, eager to try and hear what this concept achieves I thought I better rig something up with my cubes. They have three wooden legs screwed to the sides of them and are sat on 60x60x5cm concrete slabs. Even at the volumes I listen at there is considerable transfer of energy into the wooden suspended floor. If I go downstairs to the room beneath then sure enough there is plenty of distorted bass. The concrete slabs helped a little but not a massive life changing amount in the grand scheme of things.

I have currently one speaker on the inner tube isolation and the other as standard. Listening to that now and running my hand over the concrete slab and floor next to each speaker. Results later, I must now go listen down stairs and then take the inner tube out of the other wheel and hope it hasn't got a puncture.

Back soon :epopc:
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Re: Doc modding Marantz imperial 7

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The second inner tube doesn't have a flat so I pressed ahead with trying the tubes under my crappy chipboard cubes.

I found some old 40cm2 chipboard baffles to use as a platform to go on top of the inner tubes. I marked where the speakers were positioned and recorded the distance from each leg to the nearest two corners of the 60cm2 concrete slab that everything sits on. So I have the speakers in exactly the same place as they were with only one thing changing - the height. They are about 2cm taller now because of the inner tube.

I haven't matched the pressure in each tube, I don't even know what the pressure is at the moment I just went with the same number of pumps from completely flat. The pressure won't be much at all.

You can just see the tubes poking out under the chipboard platform.

Image

Image

Image

Listened to a few things so far. My thoughts to follow....
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Re: Doc modding Marantz imperial 7

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I have played a few bits from a few different albums that I played earlier before introducing the inner tubes and platforms.

Donald Byrd - Slow Drag
The Crusaders - Street life
The Blackbyrds - Unfinished Business
The Police - Zenyetta Mondatta

A few vibrational observations first. When I had only one speaker with tube under it there was some very clear differences in vibrational energy being passed. The slab and floor under the normal speaker was clearly vibrating along to the music. I could feel the bass, every kick on the bass drum, every strike of the snare. With the other speaker I couldn't pick any up really just a very attenuated low vibration.

Once I changed to both speakers with tubes under them I could feel absolutely nothing :shock: And I mean nothing. Going downstairs to listen in the room below the distorted exaggerated bass noise had completely disappeared :shock: :shock: I could hear the bass coming down the stairs with the rest of the music but that is all it was and no longer exaggerated - it was completely in line with the rest of the frequency range. Off to a good start :dance:

In every case I have been extremely surprised by how much my enjoyment of this music has grown. This is by far the best value for money upgrade I have EVER witnessed. I am sat here with a huge grin on my face, totally immersed in - the music. This is not your typical "hifi" upgrade - it appears to be fundamental and is without a doubt an upgrade. Yes it has cleaned everything up immensely (especially the bass) but it is so musical in the sense that if anything there is more dynamic and emotion in the music. The basic frequency response of my system hasn't changed, I have only put an inner tube with platform on top under each speaker. The drivers are still receiving the same signal and producing the same (except maybe no vibration coming from the floor and back into the driver's basket).

I can now not live without this addition. Listening to Donald Byrd I have never heard the brass parts to be so free. They are truly now soaring like a byrd :lol: More texture and emotion to every instrument and the band playing along as a whole. The cymbal work is so crisp and airy and floats about. The music is even more detached from the speakers. I can hear more of what kind of room the instruments were recorded in.

I think Doc would like the effect this has had. Timing is greatly improved. I have never heard Stewart Copeland's bass drum sound so fast and tight. The effects on Andy Summer's guitars are even more textured now and complete. You could call that extra detail if you wanted to.

Playing The Crusaders - Street Life. I hear the backing vocals on My lady clearer and more separated than I ever have. Percussion is now jumping out at you. It's really quite astonishing. On Street Life there was always one particular recurring bass note that sounded louder than the rest. I had tried getting it sorted but nothing worked. In the end I thought it was inherent to the recording as I have heard it on everything I have played it on. Not anymore - it is now the same volume as the rest of the surrounding bass notes :dance:

I suppose you could say I really like what this does. I don't think I will be able to continue without the new improved musical experience. And it's bloody cheap. Cost me nothing as I salvaged the tubes from an old bike. I was never likely to buy any of the Townshend products or Black Ravioli or what ever it's called. Silly, insulting prices.

I urge people to try it. What ya got to lose ?
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Re: Doc modding Marantz imperial 7

Unread post by Latteman »

Have you tried the tube coupling the sphere to the stand- would probably need a smaller size
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Re: Doc modding Marantz imperial 7

Unread post by karatestu »

Latteman wrote: Mon Jan 31, 2022 4:27 pm Have you tried the tube coupling the sphere to the stand- would probably need a smaller size
I thought about it but realised I couldn't isolate if I wanted the sphere to sit tightly in the stand with no gaps. I do think it would be better as it would take the stand out of the equation as regards vibration but I don't see how it can be done .
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Re: Doc modding Marantz imperial 7

Unread post by antonio66 »

Latteman wrote: Mon Jan 31, 2022 4:27 pm Have you tried the tube coupling the sphere to the stand- would probably need a smaller size
Get your thinking cap on Stu, I think this is a great idea, may alleviate the need to cut down the top of the stand, and I do appreciate it may not have the design appeal, but may be a better solution.
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Re: Doc modding Marantz imperial 7

Unread post by karatestu »

I will steer all my mental energy to thinking about this idea then. Maybe I just need to let go of the need to have the sphere in close contact with the stand.

Maybe the inner tube can be used to bridge the gap (in a smooth curvaceous manner) like the bumper round the wooden circle base in my pics above.

Going to need an inner tube size I don't have (12").

Look what you've done now you two. :naughty: Just when things were nearing a final design and completion. I now start thinking of how to isolate the tweeter sphere from the mid bass sphere :roll:
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