hi guys ;
long time no see .
here i propose the modification of Philips AH561 Amplifier, from single rail power supply (V+ 0) to dual rail power supply (v+ 0 v-) . i like Philips because this is the brand i had when i was a kid . 😉 . and this model is very interesting because the quiescent current is quite high in all parts .
i attached the schematics:
-- first is original schematic .
-- second is the modified schematic .
greetings from Indonesia .
long time no see .
here i propose the modification of Philips AH561 Amplifier, from single rail power supply (V+ 0) to dual rail power supply (v+ 0 v-) . i like Philips because this is the brand i had when i was a kid . 😉 . and this model is very interesting because the quiescent current is quite high in all parts .
i attached the schematics:
-- first is original schematic .
-- second is the modified schematic .
greetings from Indonesia .
Attachments
Not wishing to be awkward I cannot see the point the original amp is /was nothing special as is your proposed upgrade I am sure you can spend your time on something much better than this !
the specialty is high bias in both the ltp, the vas and the final transistor. 4ma on the ltp, 13ma on the vas and 390ma on the final transistor make this amplifier is different from most amplifiers .
Well the original is not LTP and the slightly higher current VAS has longed been used by Aurthur Bailey in his Radford amplifiers the lower values on the driver resistors has also been done many times
Your increased standing current on the front diff pairs will give an extended frequency response but at the expense of dc offset ( this can be overcome !
Do not get me wrong I do not intend t to be critical but do something new !!
Best wishes Trev
Your increased standing current on the front diff pairs will give an extended frequency response but at the expense of dc offset ( this can be overcome !
Do not get me wrong I do not intend t to be critical but do something new !!
Best wishes Trev
this amplifier is very simple . as well as simple amplifier like Aksa and P3a . I think we can maximize from this simple one . even if there are problems, such as in dco, we will find a way out later . I'm currently waiting for my pcb order to be ready .
anyway thanks Trev for your advise .
anyway thanks Trev for your advise .
totally agree with you I have every expectation it would be a nice sounding amplifier simple ones often are ! A lot will depend on layout and device selection make sure that you have it under tight thermal control re bias etc. And I am sure you will be well satisfied keep us in touch with plenty of pictures etc
Trev
Trev