Doc modding Marantz imperial 7

[karatestu]

Demand Better Audio - Envy3





From TNT review

"The finished speakers utilise a bonded construction with a unique internal texturing for resonance reduction. There is internal sphere to sphere porting to maximise the effective volume and the extremely thin (<1mm) wall thickness also helps to maximise internal volume while keeping the external size to a minimum. This very thin wall is still very rigid, I tried compressing the wall without success. The main support leg is particulate filled to reduce resonance and lower the centre of gravity, making the Envy 3 very stable in use."

"Now I have settled on the source, how do the Envy3 compare to other speakers? In my experience the Envy3 sound like no other speaker I have ever had the pleasure of using. There is no obvious box colouration, the sound is very clean and revealing of any issues with the source. During my time with these speakers I used several DACs with a range source material from regular CD rips to DSD. It was obvious each time a change was made and when the setup was right the system really shone.

"The bass appeared, at first light in character, but always well timed. After a while, you realise the apparent lightness is actually correct, there is no artificial enhancement, bloating or overhang caused by box resonance. The lack of box character is also audible in the midband with excellent clarity, it is as though the windows have been just cleaned! Using one of my reference tracks, the Tallis Scholars and the Allegri Miserere, the ambiance of the recording venue (London Church) is more apparent with the depth easier to make out. The voices are set out with some placed a significant distance behind the front singers. On some audio setups it is difficult to place the singers, you can hear them but you are not sure where the sound is coming from. With the Envy3 the depth is much more clearly defined."

"The Demand Better Audio Envy3 is an unusual looking speaker compared with the norm and this has the effect of being less dominant in your room compared to a similar box speaker. The use of leading edge technology gives real benefits, a light weight speaker with a very low contribution from the case. Some manufacturers, attempt to damp cabinet resonances by adding mass using thick walled and heavy boxes. Other manufacturers don't add mass, they either add damping materials or tune the box so it contributes in a positive way to the sound. None of these solutions work as well as the carbon fibre spheres used by Demand Better Audio."

[Geoff.R.G]

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 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.

An egg shell is very strong under compression end to end but less so equatorially. Clearly, strength depends on the materials used. However the finished speakers won’t be spheres because the drive unit has to fit in a hole and thus affects the ultimate strength.

I must admit that I was thinking wood rather than any other material and very thin wood might be a problem. Steel, Carbon fibre etc. should indeed be fine even with the necessary holes. Obviously my thinking of the Mosquito was a distraction, the fuselage was a plywood, balsa, plywood sandwich. Quite why I was thinking Stu might construct his speakers from wood I couldn’t say.

[karatestu]

So a 1mm thick sphere which is very strong and low mass. Carbon fibre is a very different material to acrylic I guess but gives hope. Acrylic is rather brittle in comparison. Just have to make sure they don't get toppled. The 35cm acrylic spheres I have found are 3mm wall thickness and I don't think I would want any thinner. Will still be light and if the legs are splayed and wide enough apart then it should be stable.

Reduced box vibration from a sphere combined with the force cancelling nature of opposing drivers might be a pleasure to behold.....or not.

[karatestu]

I must admit that I was thinking wood rather than any other material and very thin wood might be a problem. Steel, Carbon fibre etc. should indeed be fine even with the necessary holes. Quite why I was thinking Stu might construct his speakers from wood I couldn’t say.

I was (am) going to make it out of plywood but the idea was a translam construction method as shown last page where the circular rings are cut and then stacked on top of each other. That would have worked out 1 - 2 cm thickness after shaping.

I am still considering acrylic spheres (not made by me ofc) of 3mm wall thickness. That would save me a ton of work which is very appealing but I would have to get it past the wife. I must say, I prefer the look of the translam Baltic Birch speakers I have seen but the thin wall acrylic idea won't go out of my mind probably because of what I quoted earlier about the thin lightweight construction sounding better.

[CycleCoach]

Maybe it's me falling for marketing bullshit and lies but from what I have read at many places there is a compelling weight of reasons to go for a sphere. There are a few spherical speakers around but they are mostly single driver full rangers and coaxial units in point and squirt mode.

Maybe they will become more popular. Some might not be able to get their head around the idea or don't like the look. I love the look of them and as stated in something I quoted above, spheres look less imposing than monkey coffins.

[CycleCoach]

Some stuff about ferrofluid which I better park here before I forget.

It is there to mainly flatten the impedance curve - tweeters have a spike at resonance frequency which is smoothed out somewhat by the fluid. This allows a wider range of operation (frequency) and a simplified crossover. It has some (over rated) impact on transient power handling but not long term power handling.

So , when the fluid ultimately dries up and reduces the tweeter's output there is the option to remove the dried up sludge and not replace it. This would be an option in speakers like mine where the crossover region is quite high >6khz. Or you could just replace it of course. 15 - 20 years seems the life span of this stuff depending on how hard and long the system has been played. If like me you only play at low volume, have a high crossover point and have four tweeters in series sharing the voltage then it should last longer than with a single tweeter, a low crossover point and the volume much higher.

Rest assured though, it will dry out eventually and it is a slow process which creeps up on you so you don't notice until it has got so bad you think about throwing your speakers away. Stevetheshadow won't have this problem though

[karatestu]

Earlier I emailed the acrylic sphere manufacturers asking if they could supply two 350mm spheres in black with a hole at either end for the opposing mid bass. It would be nice to have matching tweeter pods so I have enquired about 150mm black spheres with four holes cut out.

They also do other colours and I quite like the brown they supply. Black or brown ? Brown looks more like wood

[antonio66]

You'd better put a link up to the manufacturer so I can see what the brown looks like, don't want to send the taste police round and have them confiscated when you've just got them finished

[karatestu]

You'd better put a link up to the manufacturer so I can see what the brown looks like, don't want to send the taste police round and have them confiscated when you've just got them finished

Just for you Dave, some dark brown acrylic



Might all be a waste of time however. The company have not replied to my email yet but I will give them a few more days before cursing them and never looking at their site again.

[antonio66]

"Passed" Could always give them a call, they wouldn't be the only company that struggles answering emails