Un subiect interesant :)

[camiloiu]

http://www.gamutaudio.com/en-GB/Blog.aspx?PID=65&M=NewsV2&Action=1&NewsId=94

Mai discutasem cu 2 dealeri despre acest tip de cablu dar acum am si a treia sursa de informatie:)

[igor1234]

Ai si testat?

[camiloiu]

Da, am testat cu un model de cablu, JPS The Power AC+ versus Transparent Powerlink Plus(dublu ecranat) versus Fisch Audiotechnik P1, maine urmeaza un alt cablu, cu sectiunea conductorilor mai mare.

Din pacate conditiile de auditie nu sunt tocmai potrivite in aceasta perioada ca sa pot face o evaluare amanuntita, insa exista diferente. In sistemul meu castigul este in scena sonora, focus si adancime.

[camiloiu]

O mica explicatie vis-a-vis de ecranarea cablurilor.

http://www.merrillaudio.net/merrillaudioaudiotips.html

[brainsmartman]

http://www.empiricalaudio.com/computer-audio/technical-papers/myths-and-snake-oil

http://www.audioholics.com/gadget-reviews/speaker-cable-and-audio-interconnects

http://www.prosoundweb.com/article/the_audio_expert_part_3_common_audio_myths/

For reasons that may initially seem unclear, the world of audio is rife with myths. Some are harmless enough provided the wallet pain isn't an issue, but some are quite malicious and potentially dangerous. Mains cables fall into the last category - many countries have very strict rules about what may be sold as a mains cable, but the vast majority of 'audio' cables have none of the required approvals. Maybe they are safe, maybe not - the rules are in place for good reasons, and based on the cost of some, paying for approval would be a drop in the bucket.

Because audio 'quality' isn't something tangible for most people, it's an area where the unscrupulous can dive in and make their outrageous claims, with little chance that they can ever be disproved. In many cases, it's only rational thinking and measurements that can really determine if something is going to make an audible difference to your system. In reality, everything that's part of the hi-fi will make a difference, and the only argument is whether it's audible or not. The charlatans will zoom into the fact (and it is a fact) that everything makes a difference, but they conveniently forget to mention that the difference will never be audible to anyone with normal hearing (or in many cases cannot even be measured). Some changes are immeasurable - we know that a difference exists because we can calculate it, but even the best measurement tools are unable to resolve the infinitesimal changes that will be made.

The limits of audibility are somewhat fuzzy - they change from person to person, day to day, and for various reasons. Hearing isn't just about ears - our brain and what we see makes a huge difference to what we hear (or think we hear). This provides a golden opportunity for anyone who is a bit shy of scruples to run rampant. Magic components, rocks, pebbles and holograms, cables that will transform your system ("better than room treatment" I've seen claimed) - the list is seemingly endless. One thing that we do know rather well ... humans cannot easily resolve a level difference of less than 1dB with programme material, yet if the scammers are to be believed, differences of 0.001dB (or even no difference whatsoever) are clearly audible to anyone who doesn't have tin ears. By applying this "logic", it becomes easy to classify anyone who doesn't hear the 'magic' as being half deaf and not credible as a commentator on the topic. The cult followers will often use this very argument to try to discredit anyone who disagrees with their nonsense.

One of the major problems is that almost zero of these so-called 'improvements' have ever been properly tested. That means a full double-blind test, where no-one knows which component is in circuit at the time of the listening test itself, and the details are revealed and statistically analysed after everyone has finished. Our senses are too easily fooled to allow sighted tests, because there will be preconceptions and (sometimes subconscious) bias towards one test item and against another. This is perfectly normal - we all do it, every day. What is not normal is that these biased views are then claimed as 'fact' and brandished around on the Net.

The result is quite predictable. People with relatively little knowledge look up to reviewers and others who claim to be 'gurus' or (lower-case) gods in the field, and if they tell porkies (lies) most are unable to detect that what is claimed is simply not possible. One only has to look at the number of complete scams that abound for 'energy savers' (as but one example). They are routinely shut down, only to open up again with a different name, but the same old scam. Quack medicos do much the same with 'miracle cure-all' products that may not even contain a single molecule of anything that might have some medicinal value.

The counter-arguments to double blind testing are so trite that they are laughable ... "The extra circuitry in the double-blind switch box (or whatever) adds (or takes away) so much extra detail (or colouration) that it makes the test meaningless." My comment on that ... bollocks! The second argument dragged out regularly is that double-blind testing is 'stressful', and the added stress means that people are unable to discern differences they otherwise might find easy. The arguments (naturally) are intended to deflect attention from their preferred test methods, which are fatally flawed.

There is another counter-argument that's often dragged out, kicking and screaming. You will be told that you must keep an open mind, because some things just work for no apparent reason. They will tell you that 200 years ago, science stated categorically that people would not be able to fly. What they fail to mention is that science has come a very long way indeed since then, and while there are still things to be discovered, they will almost certainly not be anything to do with hi-fi.

Since they have provided what they think is the perfect reason for you not to trust science, it is expected that you should try whatever idiotic 'tweak' is being suggested with a completely open mind. To do otherwise is being closed-minded and not willing to try something new. This occurs in audio probably more than in any other field, and is complete bollocks (again).

If I were to claim that listening whilst having your wedding-tackle partially immersed in olive oil improved the sound, would you do it? No, nor would any other sensible person. You wouldn't do it because it makes no sense. There is no connection between your naughty bits and sound quality, and you would rightly dismiss my claim as twaddle. Now, consider that your hearing is directly affected by many emotional triggers, as well as alcohol, many 'illicit substances', whether you had an argument with your partner, etc., etc. Dangling your privates in olive oil might actually make more difference to the perceived sound that you would have imagined, but it's still silly and you wouldn't do it. Why is it different when other equally silly ideas are proposed (such as demagnetising non-magnetic items like CDs or vinyl)? There is no difference - silly ideas are silly ideas regardless of the particular type of silliness.

One of the primary issues with these myths is that they create FUD - fear, uncertainty and doubt. Most people do not have the detailed knowledge needed to be able to determine that the latest craze or tweak is nonsense, implausible or just plain wrong. Reviewers who should be truly impartial are often anything but, and instead of dispelling myths they help propagate them. This is unforgivable in my view.

There are two particular things to which one can easily fall prey - the 'experimenter expectancy (or bias) effect' and the 'placebo effect'. Both are potentially very powerful, and can shape the outcome of a test at the subconscious level. If you 'demagnetise' a non-magnetic medium and expect to hear a difference, then you probably will. What actually caused the difference will be curdled by your brain (at a subconscious level), and you will be left thinking that demagnetising made the difference, when in fact it was 100% imagination. This is why all proper medical tests are double-blind, to guard against these well known phenomena. It is a BIG mistake to think that you are immune - no-one is immune because we don't even know it's happening.

sursa: http://sound.westhost.com/articles/myths.html

Asta ca sa nu ziceti ca n-am fost si eu rau....

Exemplele pot continua la nesfarsit din ambele tabere. Pace n-o sa fie niciodata, ca si in batalia intre religii. Chestia e simpla: crezi sau nu, restul sunt indoieli... Nu mai bine discutam de cum se aude sunetul in clasa A versus clasa AB sau clasa G? BTW, stie cineva care este diferenta intre clasa AB si clasa G?

Va rog sa considerati postarea ca si pamflet, daca vreti, nu caut sa ofensez pe nimeni si nu caut sa demonstrez nimic. Vorba lui don corleone: Capisci?

[comanr]

the charlatan = mutzunache = the big maimutzoi

este fix crezul meu in acea postare, ca sa minti calumea in jurul tau trebuie ca tu sa te minti pe tine insuti mai intai...exista oameni care pot pacali detectoarele de minciuni, probabil asa fac.

pamflet, nepamflet mie mi a placut.

[unrazesh]

Eu nu-l vad deloc ca un pamflet!

E absolut pozitiv la....marea reactie negativa!

[SpiritCrusher]

Salutare tuturor,

Desi urmaresc forumul de cateva luni, abia acum vine si prima interventie. O scurta prezentare : doar din noiembrie 2013 am intrat si eu in lumea audiofila, sa-i zicem asa. Pana atunci n-am avut niciodata un amplificator in casa. Chestia e ca m-a "pocnit" destul de tare. De atunci am investit aproape tot ce am castigat numai in scule. Si simt ca nu se va opri aici.

Sa intram in subiect. Vreau sa-mi "trag" o linie dedicata, mai mult de nevoie. Perechea de monoblocuri pe care o am de saptamana asta are nerusinarea sa se joace cu sigurantele mele. Asa ca...iata cam ce as vrea sa fac (si dupa consultarea cu inca vreo 2-3 colegi de suferinta) : din tabloul electric un cablu multibrin (3X4 sau 3X6) care printr-un conector IEC va fi bagat direct in multipriza mea, BlackNoise Six. Marea problema acum, nu stiu daca sa iau cablu ecranat sau nu. Vorbesc aici de cablul care aduce curentul la multipriza si nu de power cord-urile care vor conecta componentele mele. Daca ati studiat problema sau ati citit ceva interesant pe undeva va rog sa interveniti.

Va multumesc.

Sunet intins!

[comanr]

Nu conteaza, diferenta este fix ca aceea in care iei o cana cu apa din Dunare si constati ca ai scazut nivelul sau. Nu vad rostul ecranarii unui cablu de curent, brumul generat de un cablu de curent la 50hz este o bazaiala cu frecventa de 50hz, daca tu nu auzi nici o bazaiala de la amplificator inseamna ca poti asculta linistit muzica.

[camiloiu]

Nu cred ca este nevoie de 3x4 sau 3x6mm., este totusi prea mult la cat consum de curent ai la aparate. Cred ca daca vei torsada cei trei conductori pe care ii vei trage printr-un tub copex, va fi suficient.

[hersorin]

Eu i-am recomandat de 6 mm .

http://en.wikipedia.org/wiki/American_wire_gauge

[hersorin]

Intre prize ai mers tot cu 6 mm ? De citi amperi e siguranta ?

[Greierasul]

Nu este nevoie de ecranare la cablurile de alimentare cu tensiune de 230Vac. Daca se doreste sa fii mai catolic decat papa se poate merge pe cabluri de cupru de tipul FY cu diametrul cuprului de 6mm. De ce aceasta valoare ? In electrotehnica densitatea de curent optima asa incat sa nu ai probleme este in jurul a 1A/2mmp. Cum in general o casa normala are la priza cam maximum 16A rezulta diametrul conductorului de mai sus. Cred ca si prizele nu prea depasesc aceasta valoare a amperajului. In mod uzual se foloseste cablu FY de 2,5mm. Este mai mult decat suficient pentru majoritatea sarcinilor. Cateodata am vazut chiar si 1,5mm dar aceasta valoare nu o recomand pentru prize ci exclusiv pentru corpurile de iluminat care consuma putin in raport cu prizele.

Monoblocurile despre care se vorbeste mai sus nu dau afara sigurantele pentru ca ele ar consuma mult, ci din cauza curentului de pornire, inrush current. Aici e in are parte vina producatorului acelor monobocuri care nu a avut grija de acest aspect.

Inca un aspect important....rezistenta cablului din perente la un diametru decent este nesemnificativa in raport cu rezistentele de contact !!! De multe ori incendiile de la aceasta cauza pleaca. deci verificati dincand in cand rezistenta totala a circuitului de la panoul di sigurante la fiecare priza in parte. Este cam incomod dar asa verifici si starea prizelor.

Editat Decembrie 6, 2014 de Greierasul

[Greierasul]

Vio sigurantele sunt diferentiale ? Ca asa pare din ceea ce descrii...

[Greierasul]

Da, un termistor negativ poate fi folosit pe post de soft start dar are si el cateva neajunsuri. Unul dintre ele este ca se raceste mai greu si nu preteaza bine la porniri succesive cand poate sa nu functioneze corect. Deasemenea la curenti mici termistorul incepe sa se raceasca crescandu-i rezistenta iar ca efect este cresterea impedantei retelei vazuta de catre amplificator. Ma rog, una peste alta estebine si cu termistor.

Sigurantele diferentiale sunt excelente dar au si ele minusul lor. Daca ai condensatoare in circuit s-ar putea sa sara pentru ca exista un timp de incarcare al condensatorului in care siguranta crede ca se intampla un eveniment si da afara. In general curentul de scurgere acceptat ca nefiind periculos pentru om este de maximum 6mA parca, nu mai stiu exact.

La munca am in sala 50 de neoane si in timpul masuratorilor la SARA sunt diferente daca aceste neoane sunt sau nu aprinse. Nu este o modificare substantiala a distorsiunilor dar totusi ea este masurabila.

[hersorin]

Sigurantele sunt de 15A,una pe faza,una pe nul,cu declansare la scurtcircuit de 10mA.

Colegul se gindea sa bage o siguranta de 32A pe firul de 6 mm deoarece asa se recomanda , dar mie imi pare un pic mare . Este tot dubla . In general eu folosesc cu declansare la 300mA prin casa si 30 mA la baie (zone umede) .

[comanr]

la 32 A poti alimenta o microfabrica, o uzina mai mica, gizas

[hersorin]

Sa fiu mai concret . Folosim Diferentiale de 40 A cu declansare la 300 mA pentru camere normale , si diferentiale de 40 A cu descarcare la 30 mA pentru zone umede (bai , beciuri etc) .

Noi ne gindeam sa tragem un circuit separat de pe diferentialul de 40A cu 300 mA iar pe acel circuit sa punem un Disjunctor de 32 A .

Credeti ca ar trebui sa fie mai sensibil (10 mA imi pare extrem de sensibil ) ?

[Greierasul]

Pai in primul rand vezi la 30mA esti deja mort. Este un curent mult prea mare. 10mA cum a pus Vio cred ca este un optim foarte bun pentru bai si locuri cu risc mare. Mai departe ce dracului faci cu sigurantele de 40A ???? Cablul n-o sa-ti cedeze dar prizele in mod clar da , ca sa nu mai zicem de contacte care se vor topi. La casele din Romania generala este in medie de 25A. Deci generala nu la camere. Aveti trifazat ? Ce putere instalata aveti ? 10kVA ? Boxele sunt in asa hal de dificile incat sa folositi amplificatoare de 2kVA ? Singura explicatie logica la o casa de locuit ar fi daca incalzirea este electrica si e nevoie de putere mare si impedante extrem de mici.

Din cate stiu eu sigurante diferentiale nu se pun in camere normale, acolo unde ai aparatura electrocasnica sau condensatoare mari. Daca faci treaba asta risti sa-ti de afara mereu cand pornesti amplificatorul chiar daca acesta are soft-start. Acest circuit reduce curentul de pornire de la cativa zeci de A la cativa amperi dar tot depaseste pragul de 0,3A cum ai tu. In plus protectia impotriva electrocutarii diferentiala la 0,3A e egala cu zero, curentul este muuult prrea mare pentru om.

[hersorin]

Avem trifazat , plita electrica este conectata pe trifazat . In general in Belgia generalul e in jur de 40 A . In Romania nu e chiar asa strictete cu sigurantele de curent ca aici . De ex. eu la casa din Romania am general de 60 A (cine mai verifica) .

Aici se masoara impamintarea si vreau sa zic ca se poate ajunge cu bara de cupru pina la 15 m adincime in pamint daca nu corespunde normelor , e destul de multa strictete aici .

[Greierasul]

Si in Romania e strictete,doar ca sunt multi Dorei care cred ca stiu electricitate si isi baga mana unde nu trebuie. Impamantarea nu se face cu o singura bara ci cu un cadru de cel putin 4 bare in paralel distantate dupa anumite formule

[johndoe21ro]

Si in Romania e strictete,doar ca sunt multi Dorei care cred ca stiu electricitate si isi baga mana unde nu trebuie. Impamantarea nu se face cu o singura bara ci cu un cadru de cel putin 4 bare in paralel distantate dupa anumite formule

 

N-as merge chiar atat de departe cu criticile. Sunt convins ca in Belgia lucrurile se fac mult mai bine. Mai mult decat atat, pe la noi se folosesc mai mult bare din aluminiu si nu de cupru. Mai mult decat atat, in afara nu am vazut vreo schema cu mai mult de un electrod de impamantare!! Strictete in Romania?! Doar la prostie, din pacate.

http://www.solacity.com/docs/erico%20-%20practical%20guide%20to%20electrical%20grounding.pdf

[comanr]

sculele nu au nevoie de impamantare, cine stie ce dracu fac aia din belgia cu impamantarea, se impamanteaza cu ea.

[Greierasul]

Pentru impamantare nu se foloseste nici cupru si nici aluminiu. Se folosesc mai multe bare din cauza rezistivitatii pamantului. Nu bara in sine e problema. Ma rog, eu fiind la baza inginer electrotehnist vad lucrurile un pic altfel. In privinta seriozitatii sa stii ca este maxima pana la poarta omului altfel n-ar rezista reteaua nationala. Improvizatiile se fac in 99,99% din cazuri in casele oamenilor. Ca sa mentii o retea functionala in conditiile consumatorilor care fac tampenii crede-ma ca trebuie multa seriozitate si rigurozitate tehnica. La capitolul electricitate intotdeauna Romania a fost in top. Inca de la inceputul secolului am avut tehnicieni buni. In multe privinte Romania nu seamana cu politicienii care o conduc spre norocul lor si al nostru.

[comanr]

am si eu o mica intrebare, daca diferentialele sant audiofile?

nu vad sensul unei sigurante diferentiale intr o casa cu oameni mari , mai ales la o priza care alimenteaza niste scule, diferentialele sant folosite la baie si la casa de nebuni, aveam un electrician pe vremuri la fabrica care punea mana pe faza si zicea , vezi razvane ca aici ai 380, hop stai 500 aici, cica aicea nu i problema avem 220, nici mie nu imi venea sa cred, avea el o tehnica la atinsul firelor dar nu era normal la cap, si eu m am electrocutat de multe ori la 220 din greseala, o singura data la 500v si atunci mi a fost rau vreo 30 de minute, nu e bine la 500.