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  1. E

    Op Amp Circuit Gain Does not Match LTSpice Simulation

    Thank you for sending that circuit. This is how LTSpice simulates it. Since there seems to be a recurring discrepancy between different sims, and sims and real life, I will not add further to this thread but rather research elsewhere and get back if and when I can provide some useful information.
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    Op Amp Circuit Gain Does not Match LTSpice Simulation

    I would prefer DC coupled because there is a need to preserve the wave shape at low frequencies. But I am open to suggestions, if the DC coupling is what is limiting/clipping gain at output. The input is approx line level audio. It is a bipolar signal with a +/-1.5V swing. Many thanks for your...
  3. E

    Op Amp Circuit Gain Does not Match LTSpice Simulation

    Irrespective of the sims, the question is how can I get full expected 0-9V swing from the LM358, or at the emitter of the 2N3055, and still provide a DC offset for the bipolar input?
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    Op Amp Circuit Gain Does not Match LTSpice Simulation

    Yes, that is what I see here as well. The signal amplitude at pin 1 is good, but the wave form is not. I do not understand how that answers my question.
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    Op Amp Circuit Gain Does not Match LTSpice Simulation

    Thanks danadak, but for some reason your calculations do not match what LTSpice shows here, i.e. that the output of the LM358 (base of Q1) swings between about 1 and 10Vpp. LTSpice shows V3 to be +/- 1.2Vpp. The offset at Vin is about 1.2V (not "8V"), leaving a 1.5Vpp signal in the positive...
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    Op Amp Circuit Gain Does not Match LTSpice Simulation

    While appreciated, neither of those two observations explain the unexpectedly low voltage output. This would undoubtedly relate to the overall design, and possibly the effect of the offset on the LM358 gain headroom. I am not sure, which is why I am asking. If I use a 24VDC supply, the swing...
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    Op Amp Circuit Gain Does not Match LTSpice Simulation

    Well then, ignore the simulation and cast your expert eyes upon the circuit design. Why is it outputting only 0-5Vpp when the supply is 12VDC?
  8. E

    Op Amp Circuit Gain Does not Match LTSpice Simulation

    It's a 10A bench supply. "Out" is at the 2N3055 emitter. All supply voltages are defined by V1.
  9. E

    Op Amp Circuit Gain Does not Match LTSpice Simulation

    Sorry, I don't understand. Please explain your reply. V1 is shown as 12VDC.
  10. E

    Op Amp Circuit Gain Does not Match LTSpice Simulation

    I created an amplifier in LTSpice as shown in the diagram and asc. file below. It is intended to accept a line level audio signal from a USB audio interface, and increase the voltage and current to drive a coil. The simulation indicates an output swing of about 0-9Vpp (blue trace). This is...
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    Series Resistor in Place of Line Distribution Transformer

    I was thinking that the internally transformed 70/100V outputs would equate to more signal gain than the 4/8 ohm outputs. Conventional wisdom and raw driving power aside, I still do not understand why this added voltage cannot be controlled with series resistance at any point in the output...
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    Series Resistor in Place of Line Distribution Transformer

    Instead of using a transformer at each speaker to drop the 70V, can this not be done using series resistance? IOW what is the practical advantage of each speaker having its own step-down transformer? I am sure there is one, but I would just like to understand. Thanks.
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    Series Resistor in Place of Line Distribution Transformer

    That is exactly what I need to get started. Thanks
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    Series Resistor in Place of Line Distribution Transformer

    Sounds like it would be best if I just tried it to see what happens. I was worried about damaging the amp, but I will keep a keen eye on the oscilloscope. Thanks for the replies.
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    Series Resistor in Place of Line Distribution Transformer

    That is true. But for experiments with driving speakers at a distance I wanted to apply the higher voltage output.
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