More often than not, you only need a unity gain buffer for most filters :
www.diyaudio.com/community/threads/a-modular-analogue-active-crossover-filter-solution.329458/
In the above, the buffer is simply 2x 2SK2145GR in parallel, each configured as a simple NJFET source follower.
Performance is proven :
www.diyaudio.com/community/threads/njfets-for-source-follower-applications.329131/
If driving 2k load is not sufficient for you, maybe you can look at the Linsley Hood buffer, or that from Danyuk, or from Erno Borbely.
www.diyaudio.com/community/threads/preamp-for-hiraga-le-monstr-2024.421562/#post-7879805
All of them only require 4 transistors and can drive 600R load.
IMHO no need to go to complicated circuits.
Only for filters requiring gain in the feedback loop will require an opamp.
In that case, the easy DIY solution is already in the DIYA store :
www.diyaudio.com/community/threads/diy-front-end-2022.394339/
Patrick
www.diyaudio.com/community/threads/a-modular-analogue-active-crossover-filter-solution.329458/
In the above, the buffer is simply 2x 2SK2145GR in parallel, each configured as a simple NJFET source follower.
Performance is proven :
www.diyaudio.com/community/threads/njfets-for-source-follower-applications.329131/
If driving 2k load is not sufficient for you, maybe you can look at the Linsley Hood buffer, or that from Danyuk, or from Erno Borbely.
www.diyaudio.com/community/threads/preamp-for-hiraga-le-monstr-2024.421562/#post-7879805
All of them only require 4 transistors and can drive 600R load.
IMHO no need to go to complicated circuits.
Only for filters requiring gain in the feedback loop will require an opamp.
In that case, the easy DIY solution is already in the DIYA store :
www.diyaudio.com/community/threads/diy-front-end-2022.394339/
Patrick
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Thanks to everybody who replied! You gave me a lot of really useful information that I can study.
Now I am going to simulate some circuits, to see what i like best and after that start prototyping 🙂
Now I am going to simulate some circuits, to see what i like best and after that start prototyping 🙂
(Open Loop Gain) divided by (Closed Loop Gain) equals (Excess Gain).
Excess Gain is the amount of negative feedback available {as a function of frequency!} to reduce distortion.
You, the circuit designer, control both Open Loop Gain and Closed Loop Gain. So you control the amount of negative feedback available to reduce distortion. Most designers these days focus upon (Excess Gain at 20 kHz) since distortion is usually highest at 20k.
Excess Gain is the amount of negative feedback available {as a function of frequency!} to reduce distortion.
You, the circuit designer, control both Open Loop Gain and Closed Loop Gain. So you control the amount of negative feedback available to reduce distortion. Most designers these days focus upon (Excess Gain at 20 kHz) since distortion is usually highest at 20k.