Can someone explain to me the importance of xformer ratio in relation to tube choice/total equivalent plate (load) resistance when building a mic? I know nearly nothing about electronics, but with the help of someone who does I've built a d-ef47 mic with an ef800 tube and a bv8 is, as far as I can tell, a popular approach that Oliver Archut came up with.
However, I've read somewhere that the output impedance of the ef800 is high and should therefore be combined with a 12:1 xformer. If this were the case, I don't understand why many u47 clone manufacturers are using 6:1 xformers with tubes that have a high output impedance. I'm aware of the fact that the original design used this bv8, but in absence of the vf14 or tubes with a similarly low output impedance, isn't it very illogical from a designer's viewpoint?
I discussed this with my friend, and he says a high mic output impedance can be compensated for by using shorter cables or cables with lower capacitance/meter, but he admitted that his knowledge on tube circuitry is limited.
I found this experiment done by forum member OPR that seems to address this question:
https://groupdiy.com/index.php?topic=58091.0
To my ears, the single ef800 paired with the 12:1 ratio xformer sounds more extended and clear than with the 6:1, but who am I, when all these people that are more knowledgeable than me use 6:1 ratios?
Hopefully someone can chime in. Don't be hesitant to get technical, I'll let my friend read along.
However, I've read somewhere that the output impedance of the ef800 is high and should therefore be combined with a 12:1 xformer. If this were the case, I don't understand why many u47 clone manufacturers are using 6:1 xformers with tubes that have a high output impedance. I'm aware of the fact that the original design used this bv8, but in absence of the vf14 or tubes with a similarly low output impedance, isn't it very illogical from a designer's viewpoint?
I discussed this with my friend, and he says a high mic output impedance can be compensated for by using shorter cables or cables with lower capacitance/meter, but he admitted that his knowledge on tube circuitry is limited.
I found this experiment done by forum member OPR that seems to address this question:
https://groupdiy.com/index.php?topic=58091.0
To my ears, the single ef800 paired with the 12:1 ratio xformer sounds more extended and clear than with the 6:1, but who am I, when all these people that are more knowledgeable than me use 6:1 ratios?
Hopefully someone can chime in. Don't be hesitant to get technical, I'll let my friend read along.