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To mi nije jasno. Mogu jedno teoretsko pitanje?

MOSFET, recimo konkretni IRFP240, se nabrija mirnom strujom da bi otišao u linearni režim rada. Kod npr. Babela to je 2A. 2A štrika kroz jedan mosfet.

Ako ovde ide samo 350mA kroz mosfet, šta smo dobili? Isto kod XA serije, tamo je kod nekih i na 270mA.

Dakle on radi u linearnom režinu? Ili se gleda toplota dok koje se zagreje, pa tada ode u linearni režim?

 

Screenshot_7.jpg

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linearnost ........ jedno je linearni rezim rada za elemenat , drugo je linearni rezim za grupu elemenata

 

ako stavis mirnu struju recimo na 250mA po tranzistoru, i zahtevas od njega da jarca +/-100mA ........ to je jedna stvar

 

a ako stavis mirnu struju od 2A po tranzistoru , i zahtevas od njega da jarca +/-2A ........ to je druga stvar

 

 

sa druge strane - temperatura nema nikakve veze sa tim ...... ima posredno , ali sijaset drugih stvari su pre vezane za temperaturni domen

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sve je pitanje konteksta ....... dakle ako je naponski swing takav da ne drllja mnogo po prenosnoj krivi ..... da je promena primarne velicine ( da li struja da li napon) relativno mala u odnosu na postavljene vrednosti u radnoj tacki ...... mozes reci da je sistem linearan

 

dakle - kad pojacavas MC signal , mozes da uzmes ceve sa mizernim strujicama a i naponima ( zanemarujuci sad sve ostale faktore) , dok za driversku ceve koja treba da swinguje ihaj volata (a bogami i pokoji mA)....... mora da bude i mamara ceve

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17 minutes ago, ninja said:

Bravo majstore! Još da si ugradio USB kontakt på da bude excellence :roll1:

Nije imao dobar USB kabl, inače bi ugradio ;)

:rofl:

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Pa i ne treba USB ulaz. Dovoljno je da preko trafoa i onih silnih kondenzatora polozi jedan valjani USB kabel, sigurno ce popraviti zvuk. Uz korekciju polozaja bi se sigurno doslo do idealne zvucne slike. 

 

Salu na stranu, ovo zaista izgleda vrhunski. 

Ako moze neki hint koja je fora sa tolikim brojem kondenzatora. Versus dva tri velika...

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nije fora

stavljas sta imas

u ovom slucaju narucilac je imao ovo , to sam i stavio

 

Fata je Fata , al dvaput je dvaput

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Now , few words about THD spectra shaping ;

Papa taught us during the years several tricks how to imbalance that perfect Symmetry (ironic , isn’t it …… working principle of amp itself is called Supersymmetry/SUSY , while we are trying to spoil it :)  .

Anyway , we want some sugar , and we are getting that with 2nd harmonic above 3rd ; again – Papa’s Lectures – some people prefer that way (Tubelovers?) , while some people prefer dominance of 3rd (Sandworshippers?).

Further – we can divide both of these groups by polarity of dominant harmonic- some prefer negative , some prefer positive.

What can I do regarding that , except to find how (hardly first one knowing that) and then organize easiest way of doing it ……..

If you take a look at LTSpice schematic of amp (third pic from top) , you can see two resistor positions circled in red. These resistors are path to modulation of Aleph CCS-es and their values are directly defining amount of that modulation , thus defining amount of Aleph CCS-es contribution in output signal .

So , simple ; disclaimer – my goal is to invoke 2nd , and control it’s polarity and amount :

-If these two resistors are same in value , there is greatest amount od symmetry , resulting in zilch 2rd ,dominant 3rd.

-If we increase value of said resistor at side of positive output , there is increase of 2nd (and dominance over 3rd) , while our dear 2nd being negative phase,

-If we increase value of said resistor at side of negative output , there is increase of 2nd (and dominance over 3rd) , while our dear 2nd being positive phase.

That’s it .

How it is organized in vivo ?

I had idea to introduce sort of already know device among Greedy Boys , called -ZAP (Zen Amount Pot) , but later decided that would be impractical , and probably leading to constant play with , while forgetting enjoyment in music :)

…. so I decided to use pin sockets/or whatever their name is , in said resistor positions , thus allowing easy change of resistors in situ , without involving soldering equipment etc.pin-sockets-300x225.jpg

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Now , if you take a look at Eagle front End schematic and Eagle Front End pcb screenshot (4th and 5th pics from top) said resistor positions are R3 and R53 , with R3 being position of our special interest :

 

My taste dictate R53 being 1K , and R3 being 1K2 ; for anyone else’s taste , all what’s needed are few different resistor values and pincette/tweezers ; just power amp off , pull resistors out (gently,please) and push new one in (gently again , please).

After that you can power amp on , or go out for beer and some talk , I don’t care

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