27-07-2025, 11:30 AM
"yet they're using 2 x 16ohm speakers in parallel with 1mfd cap between them"
That doesn't make sense. Which speaker is connected direct?
2 x 16 Ohms in series is 32, but I don't know what the 1uF is for.
A 1uF is high pass, as full LF is 100 uF to 1000uF depending on speaker impedance.
The turns ratio depends on supply voltage and power and on speaker impedance of an output stage. The transistors or valves are unimportant as long as they can do the current required for the required power at the supply voltage.
Roughly for class B push pull the rating of the transistors each is a minimum of 1/4 of the output power. For Class A it's 1/2.
Most push-pull are somewhere between B and A. Depends on the bias current. Silicon transistors allow easier setting of bias accurately. There is now no reason to use Germanium except to repair an old amp or radio without changing the bias. Germanium needs a thermistor in the bias circuit.
The power limit. apart from rating of the transistors or valves, is set by core size at the lowest frequency used. More power needs a bigger core, so does 20 Hz (HiFi) rather than 300 Hz (communication or phone) lower frequency.
The speaker driver size and cabinet volume also set a lower limit on frequency.
The primary inductance sets a lower limit on frequency.
"140:35ohm impendance which suggests a 2:1 winding ratio."
But is that for full primary or half primary (half is used on each half cycle)? The max 1% distortion power (or maybe 10%) and supply voltage allows calculation of the effective primary impedance. Since it's push-pull, you double the supply voltage.
That doesn't make sense. Which speaker is connected direct?
2 x 16 Ohms in series is 32, but I don't know what the 1uF is for.
A 1uF is high pass, as full LF is 100 uF to 1000uF depending on speaker impedance.
The turns ratio depends on supply voltage and power and on speaker impedance of an output stage. The transistors or valves are unimportant as long as they can do the current required for the required power at the supply voltage.
Roughly for class B push pull the rating of the transistors each is a minimum of 1/4 of the output power. For Class A it's 1/2.
Most push-pull are somewhere between B and A. Depends on the bias current. Silicon transistors allow easier setting of bias accurately. There is now no reason to use Germanium except to repair an old amp or radio without changing the bias. Germanium needs a thermistor in the bias circuit.
The power limit. apart from rating of the transistors or valves, is set by core size at the lowest frequency used. More power needs a bigger core, so does 20 Hz (HiFi) rather than 300 Hz (communication or phone) lower frequency.
The speaker driver size and cabinet volume also set a lower limit on frequency.
The primary inductance sets a lower limit on frequency.
"140:35ohm impendance which suggests a 2:1 winding ratio."
But is that for full primary or half primary (half is used on each half cycle)? The max 1% distortion power (or maybe 10%) and supply voltage allows calculation of the effective primary impedance. Since it's push-pull, you double the supply voltage.
