Lampaš

[vojcb]

Vsak berač svojo malho hvali,...ne bom rekel, da nima v določenih stvareh prav, ampak MF mi pač ne bo pamet solil v imenu svojega interesa, ga ne bi imel in poslušal, tudi zastonj ne.
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Glasba je kot ženska, v njej lahko neizmerno uživaš......

[kalimero]

[stormsonic]

[nomad]

[ambasador]

Če pustimo ob strani 'nativno rolanje' ...

Tudi moja izkušnja je točno taka kot Michaelson opisuje (če nekomu ni všeč njegova produkcija, nima zaradi tega nobene pravice zlivati gnojnice po njegovih izkušnjah. Kot niti ne po drugih..)

V 10 letih kar imam MonitorAudio Gold20 sem preskusil na njemu skoraj vse različne topologije in moči.
Najlepše je igral s single ended lampaši, ja. In razumem vse, ki gredo v to smer, ker je izjemno zapeljiv zvok.
Me pa ni prepričalo da bi se odločil zanje iz preprostega razloga - poslušam pretežno simfonično glasbo - ker se je sesedalo ob najmanjšem znaku ataka ali crescenda.

Po raznih avanturah sem pristal na Krell-u 400. Ne zaradi bajne lepote zvoka ampak zaradi realizma ki ga 550 vatnik lahko prikaže. Pri nižji jakosti nimaš občutka da je na zalogi toliko moči. Obnaša se (skoraj) podobno kot drugi v njegovem rangu, čeprav bolj spominja na 'genetiko' posameznih instrumentov. Ko gre jakost v srednje področje se začne slišati očitna razlika. Neposredne primerjave lepo pokažejo kako šibki ojačevalci 'spustijo rep' ravno kadar bi morali 'rukniti'.

Če nimaš te primerjave pri roki si niti ne moreš predstavljati kako to izgleda. Če ste kdaj poslušali klavir od blizu - recimo iz treh metrov razdalje, potem veste kako trup klavirja trese okolico. To pride ven z močnim ojačevalcem, s šibkimi ojačevalci (tudi malimi lampaši) pa klavir spominja na plehek pianino. Podobno je z drugimi instrumenti.
Ni samo 'prazna' vršna moč (konica) amapak in predvsem polnost energije na srednjem basu (tam kjer imajo instrumenti telo) ki dajo bolj pravilno strukturo instrumentu.

Kot rečeno, velja za moj primer. Ker če bi uporabil Klipsch Cornwall, bi ziher pristal na single ended lampašu. (ni še rečeno da ne bom eni taki kombinaciji podelil domovnico).
Torej - niso naprave problem ampak nepravilna kombinacija.
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Carpe Diem

[kalimero]

[berni]

[ambasador]

Dodatek:

kadar uporabljaš res močne ojačevalce je potrebno uporabiti ustrezne kable za zvočnike. S pretankimi vodniki izničiš polnost reprodukcije.
Primer:
prijatelj me kliče: sem priklopil CodaTechnologies (330W) na zvočnike, ma ni videti da bi to bilo kaj bolj sposobno od mojega ojačevalca. Takoj sem zavohal kaj bi lahko bilo. Poberem VanDenHul Revelation kable in jo mahnem na obisk. Tam smo zamenjali njegove Kimberje (zgledajo debelo, ma so lahceni, torej ni dosti žice notri) in, magija, magija - ne slap Savice - Niagara je zgrmela ven! Zvok dobi na maestoznosti in polnosti.
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Carpe Diem

[mestn pu]

[nomad]

Ista tema, tokrat izpod peresa Rogerja Sandersa (Sanders Sound Systems):

… conventional, direct-radiator (not horn-loaded), magnetic speaker systems of around 90 dB sensitivity, require around 500 watts/channel to avoid clipping. More power is needed in larger rooms or if you like to play your music more loudly than most.
…
… audiophiles usually are using underpowered amplifiers and are therefore listening to clipping amplifiers most of the time. When an amplifier is clipping, it is behaving (and sounding) grossly differently than its measured performance would suggest.
…
In other words, we usually listen to an amplifier when it is clipping and we measure it when it is not. This is why amplifiers sound so different than their measurements would imply. It is not that measurements are wrong, it is simply that we are listening and measuring different conditions.

It is essential to understand that when an amp is clipping, it will sound quite different than when it is not clipping. It is also important to realize that different types of output devices (tubes vs. transistors) clip in very different ways, so sound quite different when they are clipping.

It should now be obvious why objective measurements don't seem to give much insight into the performance of amplifiers. It is not that objective measurements aren't accurate (they are superb), but simply that we don't usually operate amplifiers within their design parameters. So we aren't listening to them at the power levels where they operate properly and where their measurements are meaningful.

Now let's analyze tube and transistor equipment with regards to clipping, since that is the condition to which we usually listen. There is "hard" and "soft" clipping. If you go back to the oscilloscope investigations, you will see that solid state amps clip "hard" in that there is an absolute, rock-solid, limit to how loudly they will play. As soon as you reach that point, they immediately clip. This point is their power supply rail voltage.

A tube amp clips "softly." This is because tubes produce a cloud of electrons around their cathodes. This cloud has surplus electrons available so that for sudden current surges (such as musical peaks), a tube can deliver more current (electrons) and voltage for a few milliseconds before they clip. So their clipping threshold is not rigidly fixed as it is in a transistor amp. It varies depending on the dynamics of the music played.

The age of the tube matters a lot in this situation. As a tube ages, its emissions decrease and it cannot develop as many electrons in the cloud. So old tubes will tend to hard clip while new tubes will tend to soft clip.

In addition, when a tube amp clips, it produces a lot of lower harmonics in its distortion profile. Low harmonics are relatively benign and don't sound too badly. But distortion is still distortion and these harmonics don't belong there. Also, just because a tube amp makes a lot of lower harmonics, doesn't mean that it doesn't also make higher harmonics. It does. And high harmonics tend to sound dissonate and unpleasant.
…
Transistor amps tend to produce a lot of high harmonics. This is actually due more to the operation of their protective circuitry and all the spikes it produces. So generally, transistor amps will have more of the unpleasant higher harmonics than do tube amps.

It is important to note that if a transistor amp does not have any protective circuitry, its distortion profile will be much more similar to a tube amp than to a transistor amp with protective circuitry. The effect of protective circuitry is a very critical issue in the sound of solid state amps and should be more widely recognized for the problems it introduces to the sound.

What all this boils down to is that clipping tube amps sound rather soft and smooth. Clipping solid state amps sound harsh and edgy. I think it is safe to say that we would all agree that if you must listen to a clipping amp, a clipping tube amp is more pleasant than a clipping solid state amp.

It should now be apparent from where "tube sound" and where "transistor sound" comes. It comes from the sound of clipping amplifiers, which do indeed sound quite different.

Of course, when clipping, neither amplifier sounds good. They both lose their dynamics, sound "mushy", lose their detail, sound strained, tend to sound harsh (particularly transistor amps), and are somewhat distorted.

Note carefully that human hearing is rather insensitive to transient distortion, so even though both amps will produce several tens of percent distortion when clipping, we generally won't recognize the distortion for what it is, because it is too brief. Instead we will perceive and describe the sound as "harsh", "strained", "fatiguing", "muddy", etc.

To have a truly high-fidelity music system therefore requires very powerful amplifiers. Amplifier power is the single most important factor in choosing an amp. Without adequate power, all amplifiers sound badly. You can pick a clipping amplifier based on it not sounding as badly as another amplifier (tubes usually preferred over transistors), but if you really want clean, dynamic, effortless, and smooth sound, you simply must use adequate amplifier power.

In short, my take on amplifiers is to use a tube amp that clips gracefully if I must listen to a clipping amp. But I'd rather have an amplifier with so much power that it never clips! The sound from powerful amps is dramatically better than underpowered amps, even if they clip nicely.

It should now be clear that tubes only sound significantly different than transistors when you are listening to clipping amps. If the amps aren't clipping, or if you are using a component that doesn't clip (like a preamp), you won't hear any significant difference between well-designed tube and transistor equipment.

So a hybrid amp (tube front end and transistor output stage) that is not clipping will not sound any different than a pure tube or transistor amp. If it is clipping, it will sound like a transistor amp, not a tube amp, because it is the type of output stage that determines the sound of a clipping amp.

Celoten tekst je na:

http://www.sanderssoundsystems.com/technical-white-papers/172-tubes-vs-transistors

Še nekaj branja na to temo:

http://www.audioasylum.com/forums/critics/messages/30882.html

http://www.stereophile.com/reference/707heavy

http://www.harbeth.co.uk/usergroup/showthread.php?149-How-little-power-do-I-need-for-my-Harbeths

http://www.crownaudio.com/elect-pwr-req.htm

http://www.crownaudio.com/how_much_power.htm

http://www.axiomaudio.com/power

[mestn pu]

[jacoby]

Lampe ali vakumske cevi, same po sebi nič ne rolloff-ajo, znano je, da se jih uporablja med drugim tudi za VF oddajnike za nekaj 10 ali 100MHz, ali mikrovalove.
Problem nastane ker ljudje kupujejo cenene kitajske ojačevalce, ki imajo pošastno slabe topologije in še slabši material, in na podlagi teh delajo zaključke o lampaših.
Največji problem so lahko kondenzatorji in izhodni transformatorji in seveda topologija, ki je zelo pomembna. Dobri lampaši so zelo dragi predvsem zaradi omenjenih elementov, ki so osnovni pogoj, da zadeva dobro dela in da ni "rolloffa" če hočete.
Kupite kvaliteten lampaš, in sevda primerne zvočnike(dB), potem pa komentirajte.

[mestn pu]

[ProJet]

[mestn pu]