The front end needs a complete re-design.
Fit RF attenuator.
Remove P1 and insert a pair of accurately matched 100r as emitter degeneration.
Remove bc560b and insert a pair of matched bc560c.
Remove 5k6 and replace with a resistor that allows both halves of the LTP to pass exactly equal quiescent current (bias)
Remove the power grounds from the 4 signal ground connections and connect them as Signal Grounds separately to the Main Audio Ground (MAG)
Remove the base connection of T3 and fit the base between R11 and P2. Connect P2 wiper to P2 end terminal.
The ratio of C2:C1 is too low. Not 10:1, try >18:1, i.e. >=47uF
I don't know what a BSX47 is, but a BD is completely unsuitable for the VAS transistor.
R11 & R12 seem quite low in value. What is the base current passing into the Vbe multiplier (T3) and what is the current passing down the resistor ladder/string? What is left to pass as Ic of T3?
The OUTPUT stage:
What is T9?
Has someone changed the device from NPN to PNP?
If that change has been made, then I don't think it will work at all as shown.
Fit RF attenuator.
Remove P1 and insert a pair of accurately matched 100r as emitter degeneration.
Remove bc560b and insert a pair of matched bc560c.
Remove 5k6 and replace with a resistor that allows both halves of the LTP to pass exactly equal quiescent current (bias)
Remove the power grounds from the 4 signal ground connections and connect them as Signal Grounds separately to the Main Audio Ground (MAG)
Remove the base connection of T3 and fit the base between R11 and P2. Connect P2 wiper to P2 end terminal.
The ratio of C2:C1 is too low. Not 10:1, try >18:1, i.e. >=47uF
I don't know what a BSX47 is, but a BD is completely unsuitable for the VAS transistor.
R11 & R12 seem quite low in value. What is the base current passing into the Vbe multiplier (T3) and what is the current passing down the resistor ladder/string? What is left to pass as Ic of T3?
The OUTPUT stage:
What is T9?
Has someone changed the device from NPN to PNP?
If that change has been made, then I don't think it will work at all as shown.
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Hi Andrew, if I posted a schematic for a simple Class A krell, would you be able to provide suggestsion for it too?
Have a look here:
http://www.amplimos.it/images/Krell KSA100 EUR 1989.pdf
Have a look here:
http://www.amplimos.it/images/Krell KSA100 EUR 1989.pdf
the fig 1 amp schematic is not correct - bad bias, incorrect output connections - build it and it will not work
much better starting place would be Self's "Load Invariant" for 100W, CFP output and adds a few high loop gain tricks from Self's book
has the advantage of having been built, verified as working - can buy pcb, kits
much better starting place would be Self's "Load Invariant" for 100W, CFP output and adds a few high loop gain tricks from Self's book
has the advantage of having been built, verified as working - can buy pcb, kits
fast food electronics is not a good solution to learn from ...
my approach will be to work in allready exisiting and working schematic learn my ways arround it , evaluate the schmatic and effects from possible changes and then start working on something new .
the second schematic you posted has also a number of critical mistakes and always keep in mind that there is a lot of things that simulators will NOT tell you .
my approach will be to work in allready exisiting and working schematic learn my ways arround it , evaluate the schmatic and effects from possible changes and then start working on something new .
the second schematic you posted has also a number of critical mistakes and always keep in mind that there is a lot of things that simulators will NOT tell you .
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