Hi, I want to clone the pre & power amplifier section of Philips 15 AH824. The problem is i can't find 800 ohm NTC thermistor (R724), can I use 1Kohm NTC instead? For info it uses darlington transistors at the output.
I'll step out on a limb and suggest that the 1k thermistor can probably be used if you also scale R722 and R720 (and R732?) to 25% higher values. That should maintain similar interaction of thermistor's temperature sensitivity with the fixed resistors. R726 might also need to be increased if the bias pot range is inadequate. A caveat is that the amp's compensation (i.e. C560) may be affected.
Understood, but changing the NTC value is a modification of bias temperature compensation.
Good luck!
Good luck!