Instructables

what is the purpose of capacitors in audio amplifiers?

i want to know this because i want to convert a guitar amp into a bass amp and ii need to modify the right capacitors

gmoon1 year ago
Amps for guitar or bass often will work, as-is, for either type of guitar (but read my comment about speakers at the end).

As far as extending the audio range of a guitar amp "deeper" into the low frequencies, adjust the coupling capacitors is a credible approach. Amplifier stages are normally coupled together with caps to block DC from the next stage.

Those coupling caps, together with a resistor, also form a high-pass filter. Here's an example, with a filter calculator. Changing a coupling cap from say, .022 to a larger value value like 0.05 will definitely increase bass response.

Since your goal is to increase the coupling capacitance, you can add small caps in parallel with the existing caps (parallel caps increase capacitance, series caps decrease capacitance) and listen to the difference. That's a pretty easy mod.

Note that just changing the speakers to the appropriate type (bass vs. guitar speakers) will make a difference. But using a bass guitar with a stock guitar amp might blow the speakers. In fact, if the amp is modded for increased bass response it's overall output will be greater than the original design, so it's almost certain regular guitar speakers won't be up to the task...unless the speakers have plenty of extra capacity (like using 200 watt speakers with a 50 watt amp)...
iceng1 year ago
Capacitors in audio amplifiers
  1. In Biasing they Block DC signal flow
  2. In Biasing they Pass AC signal flow
  3. In Feedback they can integrate a signal
  4. In Filters they can differentiate a signal
  5. As a rule the bigger the value of capacitance the lower the frequency ( FQ ) that will pass through the cap.
  • If the capacitor goes to ground it diminishes ( shunts ) lower FQ signals out of the amplifier.
  • If the capacitor goes in series with the signal path in (pass mode) it increases the lower FQ of the amplifier.

A
Depends on the circuit. Some are there as reservoir capacitors, to smooth the power supply, some are there as signal shaping by adjusting the frequency characteristics of the amp, some are there as DC blocking components. Take your pick.....