So if I change r19 and r21 they need to match so if I change it to 120ohms the other one has to be 120ohms as well correct ?
No, you need to unmatch them to trim the offset. For example 93 ohms for one and 107 for the other. Whatever it takes.
Ahhh your picture confused me so for example I would just change out r19 with a 200ohm trim pot correct ? And I would leave r21 as a 100ohm resistor ?
The single trimmer replaces both resistors with the wiper going to the transistor above. You would use either a 200 or 220 ohm trimmer.
I'm not recommending you even attempt this because if you get it wrong it will probably not end well...…. an offset of even -/+100 mv causes only 1.25 milliwatts in an 8 ohm load.
I'm not recommending you even attempt this because if you get it wrong it will probably not end well...…. an offset of even -/+100 mv causes only 1.25 milliwatts in an 8 ohm load.
So let’s say an offset of 50mv is that enough to kill a tweeter. Cause when you initially connect the speakers to the amp that voltage goes through mind you my tweeter is a 4 ohm I really don’t want to burn another tweeter they are extremely hard to find and very expensive . I know the crossover blocks dc but the initial connection lets some voltage through that momentary voltage is that enough to burn the tweeter ?
Hey guys would it be possible if I were to double up on the output transistors and add a 5w 0.1 ohm resistor and have more power ?
Power to the load depends on the supply voltage available. A single output pair can easily cope with your -/+39 volt rails as long as the heatsink is sufficient.
Also adding another pair would double the dissipation at idle.
Also adding another pair would double the dissipation at idle.
Ya I understand I’m oversizing the heats sink . But my question is this is it possible to add another pair of transistors to the output side with the coupling resistor of 0.1 ohms 5w that’s all I would need to do correct ?
Also I got the dc offset to 6mv by just swapping and matching the bc556 transistors
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Deleted member 550749
6mv offset 👍 , u cant ad more transistor at the output at this configuration, to lower down the current flow from collector to emitter u can increase the 0.1ohm to 0.22 ohm or change it, after that there wil b more less offset , little bit less heat, try it
So I wouldn’t be able to just add two more transistor’s to double the current of the amplifier?
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Deleted member 550749
What's problem happening with ur amp right now?? 6mv is very good offset , why still u r finger the amp??? Everything looks good
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Deleted member 550749
Possibilities u can ad at Darlington configuration but over the Darlington or sziklai may b possible but for u not because there need some biasing tweek to more transistor or cal culation bypass resistor also a messy thing
Also I’m learning a lot and I mean a lot and I learn by trying breaking fixing and breaking and fixing I learn that way