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9 minutes ago, Zen Mod said:

kko bi tek zvucalo da je neka muzika ...... i da je neka postena amplifikacija

:Viannen_loungelizard:

 

Pa da... Mekintoš   kanta u odnosu šta prave Japanci u ručnoj radinosti. :smesna:

 

Ali eto..... Nisam video Japanskog Audiofila koji sluša ručno pravljen Japanski amp tipa FAL S.I.T-7000.....

Svi su na Američkoj konfekciji... :msn-rofl:

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13 minutes ago, Zen Mod said:

e Miko - -si vido plastikanere

 

:smesna:

Još kad bi ovo bila obična plastika . . . .:smesna:

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I can further add to this - although I readily admit that I am not a polymer engineer - that it would seem that the acoustic limitations of milky coloured V.F.H.Polypropylene seems to lie in the nature of its molecular backbone. Here is a micrograph of PP from which you can get an impression of how tightly interconnected the molecules are. This probably explains the rubbery or waxy nature of PP, which is notoriously difficult to glue things on to. You will note from the ExxonMobil website that polypropylene is listed as ideally suited to the manufacture of plastic buckets or car battery cases and bumpers which perfectly demonstrates the waxy nature of PP. 

To have a loudspeaker cone material which is inherently waxy or rubbery is not a good idea at all since rubber readily absorbs sonic energy! PP does have useful properties - it is (almost) the lowest density polymer available which makes for lighter cones and more sensitive speakers. It is relatively cheap. It can be moulded at normal temperatures with relatively simple equipment. It is colourless and will accept dye. It's molecular damping properties are interesting, but not 'raw', in bulk as used in V.F.H.P cones. The material itself is out-of-patent and available from many global suppliers, such as ExxonMobil. It has no known health issues. It's damping profile is interesting but highly frequency dependent (undesirable for an speaker cone).

 

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Paper cones - that's interesting. Actually, well engineered paper cones, as opposed to those made in dubious back street brewhouses with any old cardboard found lying around and heaved into a bubbling vat, have potential. If engineered properly, they have fibre strands that lie in the 3D thickness of the cone at random angles. This then, is the exact opposite of vacuum formed polypropylene in which there is a definite orientation to the molecules, akin to a grain. When forming a conical speaker cone you do not want a grain in the material because, as all DIY woodworkers know, the cut along the grain has fundamentally different properties to across the grain. Another reason for the clean Harbeth sound is that our RADIAL cones are injection moulded with the liquid plastic injected from the centre and flowing outwards - hence the name.

To explain the enormous differences between the vacuum forming process which the global speaker industry uses to make their speaker cones, and the way we make our Harbeth RADIAL cones by injection moulding look here:

Vacuum forming method: Cheap, kitchen table equipment of type used in school science labs.. Labour intensive, the object (cone) needs to be trimmed from the sheet by hand with scissors when cool enough to handle. Throw away unmoulded rim. Wasteful. No two cones are exactly alike. Danger: no control over plastic sheet film material - can sheet supplier control QC? Can you trust plastic supplier to use only virgin plastic or will he mix with reground/recycled material to cut cost? This will change sonic performance, batch to batch.

Technical cost of equipment to make vacuum formed cones: only about USD 4000.

Injection moulding method (used by Harbeth). Extremely expensive moulding machine and custom made mould tool. Zero waste. Liquid plastic squired into mould tool under huge pressure. Shape is perfect. Every one identical. Shiny surface, blemish-free. Complete in-house QC of plastic material. See attached picture of power press to make Harbeth cones which are made at the rate of about one per minute, with just one minder.

Technical cost of machine + inserts to make Harbeth injection moulded cones: about USD 400,000 

 

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Polypropylene - a general purpose plastic

Polypropylene, a milky-white material was first used as a speaker cone material by Harbeth's founder, Dudley Harwood, when he was at the BBC. He was granted a patent on the use of PP as a speaker cone, and the Harbeth company was founded upon his retirement from the BBC to maufacture (and sell to the BBC) these new PP-coned monitors (HL Mk1-3). Polypropylene can be colured (usually near-black) by the addition of dye, and worldwide most medium quality speaker cones are made from PP.

It's interesting to note that unlike Harbeths' own RADIAL material, PP was not designed as a speaker cone material, nor is it listed as being suitable or even useful as a cone material. PP is a low-cost general purpose plastic, and "most commonly used for plastic mouldings at relatively low cost and high volume, include bottle tops, bottles and fittings. It is produced in sheet form and this has been widely used for the production of stationary folders, packaging and storage boxes." "Also includes housewares, rigid packaging containers, toys, disposable medical syringes, video cassette cases, appliance housing/outdoor furniture and luggage. Non-woven applications include insulation wrap, disposable diapers, automotive interiors and medical textiles".

PP is a most useful general-purpose and low cost material but it does not boast specific acoustic properties, nor would you expect it to, as it is not really an 'engineering plastic'. But it is extremely easy to mould using nothing more than a kitchen grille. And cheap. It ihas lower mass than previous generations of material (bextrene) and hence will make a louder, loudspeaker and some say that it does not need to be doped to suppress coloration. Bextrene always needed a thick layer of dope to tame its 'quacky' coloration.

Data sheets showing applications ....

Wiki
Datsheet

Attached is a diagram which shows what we believe is the main issue with PP - the cross linking of the molecules. Each one of those billions of 'tethers' where the molecular chains curl up against an adjacent chain results in a tiny sponge, and this strips the fine detail from the sound wave as it travels through the cone.

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Harbeth?s secret in the quest for an ultra-pure sounding loudspeaker:....

As a highly innovative British-owned loudspeaker brand, we have decided to tell the world the secrets to our unique cone material after almost two decades of secrecy. While conventional loudspeakers depend on materials originated for other purposes, RADIAL? is the first purpose-designed for speaker cones.

Harbeth Audio developed RADIAL? cone technology after a substantial grant from the British government. The ten man-year project, begun in 1990, resulted in what has proved to be a world-beating solution to the many problems inherent with conventional speaker cones which rely on paper, shampoo-bottle plastic (polypropylene), or woven material. None of these were tailored for the audio industry but have been adopted because of their cheapness. Now Alan Shaw, Harbeth?s designer and MD can spill the beans on his secret formula. It?s all about ensuring the polymers in the cone material are kept separate so that sounds are not lost as heat from friction between the molecules.

?Turning sound into heat is the worst possible scenario for a hi-fi listener?, admits Alan. ?Because you can never change the heat back into sound ? it is lost forever.?

RADIAL? is a complex blend which contains a special ingredient which prevents the plastic becoming waxy with a ?rubbery? feel ? as is inherent with soft and squidgy polypropylene.

?It?s a bit like comparing a soft jelly baby to a hard, boiled Foxes glacier mint?, explains Alan. ?One is soft and malleable, the other rigid and can?t be bent out of shape by the sound waves passing through.?

You can see the effect by squeezing any empty polypropylene container found around the home ? they are all marked with the ?double P? symbol and a triangle. The highly stiff RADIAL? cone produces a long, clean decay time ? just as in the concert hall. Conventional cone materials, on the other hand, make the walls sound cotton-wool covered ? ?an acoustic fog?, says Alan.

?Take a single piano note as an example?, says Alan. ?With a Harbeth RADIAL? cone the note will sound realistic, as if in the concert hall with the actual piano. However, when played through a speaker with conventional cones, the note dries out prematurely as the decay is shortened. With a woven cone there is another problem from unwanted ringing as the note dies away.?

Quite simply ? RADIAL? technology is what makes Harbeth speakers unique, and such a hit with broadcasters and audiophiles around the world.

 

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Coloration in speaker cones: the Harbeth advantage

Whilst investigating for my own curiosity what they've technically done in the remastering of The Beatle's Sgt. Pepper's Lonely Hearts Club Band using software that allows an instantaneous comparison of the old v. new recordings I've found a very useful software facility. (We'll return to the Sgt. Pepper later).

As you now, we and Harbeth users expect the midrange clarity that only our RADIAL? cone material can yield and we've talked about this many times over the years; superior cone technology is the core concept behind the Harbeth reputation for clarity. "Conventional cones mask detail" - I've said that for over twenty years. Our entire commercial success has depended upon that fact. Anyone who has made a side by side comparison between a conventional (polypropylene) cone and a Harbeth RADIAL? cone doesn't need me to tell them that you can hear details on the Harbeth that are lost in the acoustic fog of a conventional cone. It's subtle, but quite definitely a real perforance advantage and the more you are exposed to the clarity of RADIAL? the more stark the comparison with polypropylene, or other materials.

Now the opening statement: most good speakers can sound reasonably similar in the lower and middle registers; the differentiation of quality generally becomes more apparent in the presence and low-treble region, where the human ear is especially - I means extremely - sensitive. Read here. This presence region, covered by the top end of the bass/midrange unit is where I detect the defining differences between speakers, and specifically, between speaker cone materials. Polypropylene cones, patented by our founder Dudley Harwood, used in the Harbeth Mk1-3 and most commercial speakers these days, was abandoned by him for his last monitor, the Mk4 and I continued with that concept into the now current Harbeths.

So, what we're looking to demonstrate if we can here, without you having to actually listen to a Harbeth, is how a conventional speaker cone fogs the detail especially in the presence region. I've found a way to synthesise that, but first I'd like to give you some more technical background to make the demonstration understandable. If this is demonstrable over the internet as it is here, then I have achieved a life long ambition!

Alan A. Shaw
Designer, owner
Harbeth Audio UK

Izvor https://www.harbeth.co.uk/usergroup/forum/the-science-of-audio/213-harbeth-radial-v-other-cone-materials

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