Secret to a Reliable Repaired Crown Amplifier

Only available at the AE Techron Repair Center


BJT transistor resistance decreases as they get hotter.

This is a problem when making big amplifiers with BJT transistors. To create higher power amplifiers (greater than 100 watts), these transistors need to be connected in parallel.

When multiple BJT devices are connected in parallel, if one of them has a lower resistance, it will handle the greatest amount of the power.

This causes the transistor to get hotter and its resistance to drop further, which requires it to handle an even larger portion of the amplifier’s total power.

This heating, lowering of resistance, then further heating continues until the device fails.

This is called Thermal Runaway.

Thermal Runaway Cycle

Crown Solution:

All linear topology amplifiers made by Crown use bi-polar (BJT) output transistors.

A significant part of the Crown reliability can be attributed to grading and then only using output transistors in grade matching sets, avoiding the fatal Thermal Runaway issue.

For your amplifier to perform like it did when it was new, it is very important to only use graded output transistors to repair your Crown amplifiers.

The AE Techron Repair Center purchased the transistor grader used by Crown to do this matching and is the only repair center able to offer graded output transistors when repairing Crown amplifiers.

The numbers on your output transistors indicate the grading.

Graded Transistors in Amplifier


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Visit our Repair Center:

AE Techron, Inc.
2507 Warren St.
Elkhart IN 46516 USA