Hi!
I plan to build a fvp5a. I do not have a SK170 or similar, but I do have one MAT12 dual matched NPN transistor pair. This should be more or less similar to the MAT02 that Allen Wright recommended for the RTP3C insted of SK170 etc. Can I use one MAT12 for a stereo fvp5a? One transistor for each channel? Or do I have to find some matched SK170/147/369? If so, I suppose a high Idss is preferable?
I am a newbie when it comes to transistors. I have tried to find some information on interchangeability between SK170 and MAT02/MAT12 for fvp5a, but have not found much. I have found at least one place that this may not be possible, though, but I can not quite see why, probably because I do not quite understand the difference in how these works...
Regards,
Oyvind Saanum Eithun
I plan to build a fvp5a. I do not have a SK170 or similar, but I do have one MAT12 dual matched NPN transistor pair. This should be more or less similar to the MAT02 that Allen Wright recommended for the RTP3C insted of SK170 etc. Can I use one MAT12 for a stereo fvp5a? One transistor for each channel? Or do I have to find some matched SK170/147/369? If so, I suppose a high Idss is preferable?
I am a newbie when it comes to transistors. I have tried to find some information on interchangeability between SK170 and MAT02/MAT12 for fvp5a, but have not found much. I have found at least one place that this may not be possible, though, but I can not quite see why, probably because I do not quite understand the difference in how these works...
Regards,
Oyvind Saanum Eithun
Have I understood correctly if I say that jfets (SK170 etc.) needs a negative bias on the gate relative to the source (as in a triode)? If so, that will work in the fvp5a. And does a BJT, as I suppose MAT12 is, need a positive bias on the base relative to the emitter? If so, I can not see how the fvp5a can arrange that, but the RTP3C can, as it uses a negative supply on the source/emitter.
So I suppose I really need a pair of SK170...
Regards,
Oyvind Saanum Eithun
So I suppose I really need a pair of SK170...
Regards,
Oyvind Saanum Eithun
Have a look here for possible subs for the SK170: Linear Systems || Home
There is a fellow selling matched pairs of several different types of fets including the SK170 and is referenced somewhere within this thread: http://www.diyaudio.com/forums/digi...-sen-evolution-minimalistic-iv-converter.html
There is a fellow selling matched pairs of several different types of fets including the SK170 and is referenced somewhere within this thread: http://www.diyaudio.com/forums/digi...-sen-evolution-minimalistic-iv-converter.html
Hi Oyvinsa,
You are correct about jfets and bjts. The fet is a normally on device so the gate-source junction must be reverse biased to turn the device off some. The bjt is a normally off device so the base-emitter junction must be forward biased to turn the device on some. You can't just swap a bjt for a fet in a circuit because of the different bias requirements.
Ray
You are correct about jfets and bjts. The fet is a normally on device so the gate-source junction must be reverse biased to turn the device off some. The bjt is a normally off device so the base-emitter junction must be forward biased to turn the device on some. You can't just swap a bjt for a fet in a circuit because of the different bias requirements.
Ray
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