Why do solid state guitar amps need so many op amps?

razorrick1293 · 7th June 2011, 11:58 PM

Ok, ive been playing with both solid state and tube amplifiers for quite a while now, but can anyone tell me why most solid state amps (even the cheapest ones) use between 8 and 20 opamp stages? the best solid state amp ive heard used a single opamp and 3 JFETs... dont these companies want to make these things as cheaply as possible? and all of these are for tone shaping, whats wrong with passive filters?

Andy5112405 · 8th June 2011, 07:51 AM

Most of the cost of an amplifier is in research and development. It is just quicker to use "Building Block" approach, with each block using its own op-amp.

The PCBs are computer generated so "cheap" and the components are "cheap".

ampmade · 8th June 2011, 10:06 AM

It depends on the functions available on the amp. If there is lot of filter, an effect send, return...
All of these stages need opamps to make filtering, buffering or gain.

Basically, it's true that you can make a very simple guitar amplifier. A gain stage for the input (INA217 can do this job for example), followed by a phase inverter that drive the power stage (AB class push-pull in many cases).
No filtering, just voltage gain and current gain.

7th June 2011, 11:58 PM	#1
razorrick1293 diyAudio Member Join Date: Nov 2010 Location: England Hertfordshire	Why do solid state guitar amps need so many op amps? Ok, ive been playing with both solid state and tube amplifiers for quite a while now, but can anyone tell me why most solid state amps (even the cheapest ones) use between 8 and 20 opamp stages? the best solid state amp ive heard used a single opamp and 3 JFETs... dont these companies want to make these things as cheaply as possible? and all of these are for tone shaping, whats wrong with passive filters?

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8th June 2011, 07:51 AM	#2
Andy5112405 Banned Join Date: Nov 2006 Location: Torpoint	Most of the cost of an amplifier is in research and development. It is just quicker to use "Building Block" approach, with each block using its own op-amp. The PCBs are computer generated so "cheap" and the components are "cheap".

8th June 2011, 10:06 AM	#3
ampmade diyAudio Member Join Date: Jun 2006 Location: Verviers	It depends on the functions available on the amp. If there is lot of filter, an effect send, return... All of these stages need opamps to make filtering, buffering or gain. Basically, it's true that you can make a very simple guitar amplifier. A gain stage for the input (INA217 can do this job for example), followed by a phase inverter that drive the power stage (AB class push-pull in many cases). No filtering, just voltage gain and current gain.