Audio Engineering

362 Chapter 11 Although there are a number of factors that determine the phase shifts within the transformer, the two most impor ...

Valve (Tube-Based) Amplifi ers 363 urged that, for good LF stability, the value of permeability, μ , for low values of B should ...

364 Chapter 11 proposed that eight secondary segments should be placed in the gaps left between 10 primary windings. This increa ...

Valve (Tube-Based) Amplifi ers 365 given for 1 and 2% THD values by a push–pull pair of U/L-connected KT88s in relation to the a ...

366 Chapter 11 References ...................................................................................................... ...

Negative Feedback Douglas Self It is diffi cult to convince people that this frequency is of no relevance whatsoever to the spee ...

368 Chapter 12 how high the feedback factor. The linearization of the VAS by local Miller feedback is a good example. However, m ...

Negative Feedback 369 One approach to appreciating NFB and its stability problems is SPICE simulation. Some SPICE simulators hav ...

370 Chapter 12 fi gure for a bipolar input with some local feedback. Stability in an amplifi er depends on the amount of NFB ava ...

Negative Feedback 371 Note that this is strictly a linear model, so that the slew-rate limiting associated with Miller compensat ...

372 Chapter 12 NFB amplifi er depends on the open-loop gain available. Once more elementary feedback theory is brought to life. ...

Negative Feedback 373 40 V 30 V 20 V 10 V 0V 0 s 1.0μs 2.0μs 3.0μs 4.0μs 5.0μs Time 50p 100p 220p 50p 100p 220p v(3) v(7) Figure ...

374 Chapter 12 and shows only damped oscillation. Figure 12.7 shows over 50 μ s what happens when the amplifi er is made very un ...

Negative Feedback 375 known Ft of power transistors. Practical amplifi ers are likely to take off at around 500 kHz to 1 MHz whe ...

376 Chapter 12 1.0 kV 0.5 kV 0V 0.5 kV 0s 10 μs20μs30μs Time 40 μs50μs v(3) v(7) Figure 12.7: Adding a third pole makes possibl ...

Negative Feedback 377 In the fi nal case F, a sixth pole is added to see if this permitted sustained oscillation is above 500 kH ...

378 Chapter 12 textbooks give a very full treatment of this stability criterion.) An intersection of 12 dB/ octave is defi nitel ...

Negative Feedback 379 Further Reading........................................................................................... ...

380 Chapter 12 Sandman, A Class S: A novel approach to amplifi er , Distortion Wireless World, September 1982, p. 38 Sinclair , ...

Noise and Grounding Douglas Self 13.1 Audio Amplifi er Printed Circuit Board Design ............................................ ...