My lm1875 configuration
leg 1. 10k resistor to earth
leg 2. 10k resistor audio in
leg 3. ve-
leg 4. out speaker
leg 5. ve+
220k resistor between leg 2 and 4 (nfB)
Sound good but have diferences in the sound when exchange the resistors.
Small metal films.....clear but metallic sound
To 1 per cent resistors.....soft clear but no have body the music...less bass.
What type use?
and in the the V+,V- caps what type...multilayer,mkp,poly,plastic poly?
pc board or air connections?
leg 1. 10k resistor to earth
leg 2. 10k resistor audio in
leg 3. ve-
leg 4. out speaker
leg 5. ve+
220k resistor between leg 2 and 4 (nfB)
Sound good but have diferences in the sound when exchange the resistors.
Small metal films.....clear but metallic sound
To 1 per cent resistors.....soft clear but no have body the music...less bass.
What type use?
and in the the V+,V- caps what type...multilayer,mkp,poly,plastic poly?
pc board or air connections?
I think you have built an inverting chipamp.
The 10k to leg2 defines the input impedance of the amplifier and also controls the gain.
Anything at the input in addition to the 10k WILL affect the sound coming from the output. It's intrinsic to an inverting amplifier.
I suspect the sound quality characteristics you are describing are more down to the effect the source and volume control and cable and lack of RF interference and DC offset have rather than to component type in the amplifier. All these source effects are part of the gain structure of an inverting amplifier.
I am not saying; don't build an inverting chipamp. What I am saying is; understand what you have and look in the right place for an explanation.
The 10k to leg2 defines the input impedance of the amplifier and also controls the gain.
Anything at the input in addition to the 10k WILL affect the sound coming from the output. It's intrinsic to an inverting amplifier.
I suspect the sound quality characteristics you are describing are more down to the effect the source and volume control and cable and lack of RF interference and DC offset have rather than to component type in the amplifier. All these source effects are part of the gain structure of an inverting amplifier.
I am not saying; don't build an inverting chipamp. What I am saying is; understand what you have and look in the right place for an explanation.
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