Hocam selam,
Ben 20 senedir bu isin icindeyim, ogrenci degilim. Elektrik-elektronik muhendisliginde doktoram var,
piyasada 10 seneyi askin suredir calismaktayim. O yuzden karsinda bu konuda amator kulaktan-duyma
bilgiyle konusan birisi yok, onu belirtmek istedim.
Ben sana senin gosterdigin negatif-tersleme tarzinda yazmiyorum , ama benim dediklerimin hepsini aynen
ders kitaplarinda ve internette bulabilirsin. Bir yanlisim veya eksigim varsa soyle, ama ilgili belgesiyle
veya internetten bir link gostererek ilet ki eyvallah diyelim.
Elektrikte guc tanimi "intantaneous power" yani o andaki guc, "Peak power" tepe-guc, ve
"average power" averaj-guc, "RMS average power" RMS-averaj-guc diye degisik sekillerde tanimlanabilir.
Simdi bu tanimlarin hepsi farkli sekilde hesaplaniyor, ben sana piyasada genel-gecer olan RMS-averaj-guc
tanimindan bahsettim. Dikkat edersen amfi ureticileri hep RMS-averaj-gucten bahseder urun brosurlerinde.
Boyle bahsetmek zorundalar zaten, cunku muzik sinyali herhangi bir standard matematik fonksiyonla
tanimlanamayacak kadar dinamik bir sey. Bazi ureticiler (Bugera gibi mesela), amfilerini "peak-power" ile
fazla Wattli gosterip satmaya calisiyorlar ki ucuz bir pazarlama taktigi.
Sabit akim-voltaj farkiyla ilgili bu sitedeki "
http://lenardaudio.com/education/12_amps_8.html"
yazidan alinti yapiyorum:
"
Valve amplifiers naturally function in quasi Current-drive and have a higher audiophile musicality status.
It is virtually impossible to make a Valve amplifier function in 100% Voltage-drive in the same way as a
solid state amplifier. Many manufacturers of musical instrument amplifiers (Fender, Marshall etc)
stayed with Valve technology for this reason.
Why is this fundamental difference between Voltage and Current drive rarely understood or spoken
about by the majority of self proclaimed audio experts, text books, web sites or forums.
Rarely is there any connection to this description as being the primary cause for the difference
between how Valve and solid state amps sound. Almost all explanations about differences
between solid state and Valve amps is based on romanticised subjective twaddle.
Why was Voltage drive originally chosen as the convention for solid state amplifiers ?
Questions of Voltage and Current drive
1 In Voltage-drive the amplifiers specifications of flat frequency response, gain and internal distortion figurers
are not influenced by the speaker. Except for total power all amplifiers in Voltage drive behave identically.
Resonant peaks within the speaker system are damped and not amplified. Tweeters and compression
drivers preform better when driven with an amp in Voltage drive and not current drive. Voltage drive
enables speaker system designers to have independence with predictability and simplicity. This enables
ported boxes to be easily designed and allows high order complex passive crossovers, which are highly
reactive, requiring maximum damping from the amplifier to work correctly. Because all amplifiers are made
in Voltage drive it does not need to be mentioned or explained. Amplifiers and speakers are marketed
independently of each other, therefore it is simply pragmatic.
2 In current-drive the amplifiers frequency response, gain and distortion figurers are dependant on
the speaker system. The amplifier and speaker are now interactive and complex to understand.
Resonant peaks within the speaker system are not damped and therefore amplified.
Current drive is not suited for most applications of ported boxes and complex passive crossovers.
Current drive as with most valve amps is best suited to sealed critically damped speaker cabinet designs,
with constant impedance passive crossovers, and active systems where each amplifier is matched
to its speaker. Early passive crossovers were mostly second order, and critically aligned to avoid
resonant effects. Some earlier speakers had copper caped pole pieces, which helped damp
impedance variations. Valve amplifiers, which naturally function in quasi current drive, are sensitive
to resonances in crossovers and impedance variations. Therefore a flat impedance was synonymous with
a flat frequency response.
3 The technical differences between Voltage-drive and Current-drive is neither right or wrong
but the result of application management. However the failure for not allowing solid state amps
to be optionally available with switchable Current-drive management can be challenged in reference
to technical educational attitudes attaining to moral righteousness, similar to religious beliefs.
Technical reference PDF download
Distortion Reduction in Moving-Coil Loudspeaker Systems Using Current-Drive Technology. PDF
by P. G. L. Mills and M. O. J. Hawksford.
"
Konusmayayim diyorum ama insani cileden cikariyorsunuz.
Once geldin dedinki "Watt'in tanimi genelde tek frekans icin (sinus dalgasi), ve RMS olcumler kullanilarak yapilir."
Bu dedigin sey watt tanimi falan degil. Amfinin cikis gucunden bahsediyorsun ama yanlis terimlerle. Amfinin cikis katinin kac watt guc uretebilecegi hesabi yapilirken giris sinyali elbette sinus kabul edilir ama RMS olcum diye bir terim yok. RMS, efektif degerdir. Amfinin kazancini hesaplar, belirlenen sartlarda uretebilecegi maksimum gucu hesaplar daha sonra bu gucun efektif degerini istersen bulursun. Ama bunun konuyla yakindan uzaktan alakasi yokken tutmus bide RMS nedir anlatmaya calismissin. Ama ne amfinin yapisi belli ne cikis empedansi belli, sari cizmeli mehmet aga.
Diyelim ki diyelim ki, tamam ozaman speakera 16 ohm diyelim ozaman ne olacak? Bahsedilene cok yakin olunca ne oldu, nedir yani hedefin su hesabi yaparken? Bildigin herseyi kafandaki siraya gore, konuyla alakasi olmaksizin soyluyorsun, amac ne? Ne kanitlamaya calisiyorsun?
1 khz orta frekans kabuludur, sinuste ses sinyali olarak kabul edilir. Oyle oldugundan degil sadece kabul, yani sen gitarda tek nota basinca sinus falan cikmiyor ortaya. Sinus sinyali ureten diyopozondan baska dogal kaynak yok, varsa da bilmiyorum. THD ses amplilerinde %5 altinda tutulur ama gitar amplilerinde boyle bir kaygi yok, yine niye bunlari soyluyorsun konuyla ne alakasi var anlamis degilim.
Okudum, tesekkur ederim cok guzel bir yaziymis fakat burda; Lambali amplilerde sabit akim uretildigi ya da solid state lerde sabit voltaj uretilmesi ile ilgili bir bilgi mevcut degil.
Bu yuzden degil, dusuk yuk baglarsan yuksek akimdan dolayi primer sargisini yakarsin, yuksek yuk baglarsan primer izolasyonunu delersin, yoksa arada trafo olmasa bir sakincasi yok istedigin yuku bagla.
Ben de muhendisim benim karsima heryerde cikmadi o 3 dB, biyerde hata mi yapiyorum acaba. Muhendislik okuyorsun veya ogrencisin ya da hobi olarak ilgileniyorsun, birseyler bildigin belli ama yanlislarin var. Biz bu forumda yillardir yaziyoruz, yeri geliyor teknik olarak tartisiyoruz zira meslegimiz elektrik bu sebeple canini sikmak ya da gereksiz tartismalara girmek istemedigimden dolayi yukardaki gibi alakasiz yerde yapilmis aciz hesaplamalarla gelirsen cevap vermeyecegim. Lambali ampli de nasil akim sabit oluyor, solid state amplide nasil gerilim sabit oluyor bunu aciklarsan, konusalim.
