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How many transistors are enough?

I'm not that technical. I'm a musician who just wants my system to sound as good as it can within my budget. To that end, I'm wondering about transistors in a solid state amplifier. Specifically, how many per channel is enough? I currently have a pair of mono-block amplifiers with six transistors each. I have been shopping around and have noticed that some amplifier manufacturers emphasize the number of transistors per channel. For example, a Parasound JC-5 touts 12 transistors per channel for a grand total of 24. Can someone please explain to me and to the other Audiogoners out there who may not know, what function does a transistor have in an amp and how many transistors is considered sufficient or optimal? Thank you in advance for your considered responses.

 

diminishedchord

Showing 2 responses by erik_squires

erik_squires
15,791 posts
 

Another consideration I forgot to mention is class A designs. For the same power rating (say 50W) a class A amplifier must dissipate a lot more heat and power continuously, and having more transistors means more overall heat dissipation is possible.

erik_squires
15,791 posts
 

Hey,

You can make a good amplifier with 2 output transistors per channel. Maybe even 1 with the right designs if low power.

The excess in output transistors is for dreadnaughts. "Fear nothing" designs. They do a couple of things:

  • Increase the maximum safe current capabilities
  • Reduce the need for negative feedback.
  • Reduce the output impedance, making them behave like ideal amps no matter how hard to drive your speakers are.

Sanders speakers has a number of these overbuilt amplifiers for relative bargain prices that sound great and will drive anything. Several models you can literally short safely. The power supply will run out of juice before the output stages ever do. Many other amps will fry if you short the outputs even at low output levels.

Most amplifiers are somewhere in the middle between minimum and complete excess. Luxman integrateds are differentiated almost entirely by the power supplies and the number of output transistors.

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