Elektroniikka ja soitinrakennus ›

Mun mielestä pelkkä biasointi pitäisi riittää? En ole satavarma.
Pitää tsekata:
Ulostulomuuntajan tehonkesto (Pitäisi riittää kun 6550 on jytkympi kuin el34)
UT-muuntajan impedanssi hyväksyttävissä rajoissa?
Onko putken pinnien järjestys sama?
http://tdsl.duncanamps.com/tubesearch.php
 
Pitääpäs tutkailla! Kiitoksia infosta!
 
Paljon tuon UT- muuntajan impedanssi pitäisi olla?
 
Edit:
Löysin tällaisen:
 
"European" values for JCM 800s with EL34s are:
 
22k variable resistor = bias adjust pot
56k divider = resistor in series with bias pot
220k bias splitters = the two resistors connected to the other end of the divider resistor
Purple feedback wire on 8-ohm tap
 
Amps built for the US market with 6550s had/have:
 
22k variable resistor = bias adjust pot
47k divider = resistor in series with bias pot
150k bias splitters = the two resistors connected to the other end of the divider resistor
Purple feedback wire on 4-ohm tap
 
A "complete" conversion would entail changing the components to make the US amp look like the European amp. The main issue is getting the voltage adjustment range into the right area.
 
A simple procedure that works is (copped from the Voodoo Amps website):
 
MARSHAL 6550 to EL34
1.) Locate the 47K resistor above the bias pot and solder another 47K in parallel.
2.) Set the bias pot the max (around -38 volts).
3.) Locate the purple feedback wire (that is connected to the 4 ohm speaker tap) and solder it onto the 8-ohm speaker tap.
4.) Install the EL34’s and re-bias the amp.
 
I did this mod to my JMP 2203, and it works fine. I tried the 220k bias splitters and decided I liked 150k better so I put them back in. YMMV.
 
Just look inside and see if any of this jives with what you see in your circuit.