ST-70 Mods

Postby JojoD » Thu Jun 16, 2005 2:52 pm

ST70 gurus and afficionados,

Ask ko lang po question regarding the amount of current flowing on each power tube of the ST70.

Assuming that the bias voltage is equal to 1.56V and that the output cathode resistor being a perfect 15.6 (5W) ohms then there would be about 100mA flowing to that resistor right? Assuming also that the EL34s on each channel are "perfectly" matched, and since the cathodes of the two EL34s are tied together, then each power tube is biased at 50mA each, is this correct?



Thanks,
JojoD
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Postby mozilla » Thu Jun 16, 2005 4:54 pm

Yes tama.

Amp=Volt/R
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Postby JojoD » Fri Jun 17, 2005 6:41 am

hi mozilla,

thanks!

btw, up to what wattage does the st70 operate in class A? is there a way to calculate when the amp will switch into class B operation just by knowing the tube current? or would this need some major measurements and tools?

thanks again!
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Postby mozilla » Mon Jun 20, 2005 12:05 pm

Hi Jojo, not so sure about this. I think its Class A up to 15w and AB thereafter.
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Postby JojoD » Mon Jun 20, 2005 12:24 pm

Hi mozilla,

Thanks! That may explain the ST70's reliability and excellent track record, no wonder it is loved all over the world.

Cheers,
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