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weird opamp configuration
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wraper:
The only thing where you could see a voltage swing above a few volts is inside a power amplifier stage. But there is none on this schematic.
stojke:
I am no electronics expert, all I know is from practice, but this amplifier should sound a lot louder and at a lot lesser turn of the volume pot. The owner confirmed this, some reseller, by owning multiple units where the others had a greater amplification than this one.
Still , it makes no sense for an amplifier not to amplify the input signal , whats the deal with that?
It only made sense that due to failed capacitors the voltage should be higher, and also an parallel from an Akai amplifier that amplifies the input signals via an opamp setup to almost 15x on maximum volume. (In Akai case volume pot being before the opamp)
wraper:

--- Quote from: stojke on January 18, 2019, 11:10:28 pm ---I am no electronics expert, all I know is from practice, but this amplifier should sound a lot louder and at a lot lesser turn of the volume pot. The owner confirmed this, some reseller, by owning multiple units where the others had a greater amplification than this one.
Still , it makes no sense for an amplifier not to amplify the input signal , whats the deal with that?
It only made sense that due to failed capacitors the voltage should be higher, and also an parallel from an Akai amplifier that amplifies the input signals via an opamp setup to almost 15x on maximum volume. (In Akai case volume pot being before the opamp)

--- End quote ---
If both channels have the same volume, I would assume likely there is no failure. As I already said, what you have measured on this part of the circuit is completely fine and expectable. It might be that what you are using as signal source has too low voltage swing. As it seems, this circuit is supposed to have around 1 Vrms nominal at it's input.
ArthurDent:
Stojke - "Still , it makes no sense for an amplifier not to amplify the input signal , whats the deal with that?"

Voltage followers by definition have a voltage gain of one. They are used for impedance matching and current gain. You could have a power amplifier (not a preamp) with a gain of one. Even though the input and and output voltage of a unity gain power amp could be the same, there is no way you could eliminate the power amp and drive speakers directly from a preamp. You have to realize there is a difference between voltage gain and current gain. Read and understand the following. Google is your friend.

https://www.electronicshub.org/power-amplifier/
TrickyNekro:

--- Quote from: stojke on January 18, 2019, 11:10:28 pm ---I am no electronics expert, all I know is from practice, but this amplifier should sound a lot louder and at a lot lesser turn of the volume pot. The owner confirmed this, some reseller, by owning multiple units where the others had a greater amplification than this one.
(In Akai case volume pot being before the opamp)

--- End quote ---

Are you sure, you don´t have a short in the input of the power amplifier sector? Are you sure that the op-amp you have placed there can drive the input stage? (although there is a resistor so it shouldn´t be the case). Cause this is a buffer / voltage follower. This part does NOT amplify, unless it uses an op-amp with internal gain. But a normal op-amp would simply NOT amplify the signal, it only acts as a buffer between filter stages most probably, but I bet my degree on this, this is NOT an amplitude amplifier. Probably you have a problem elsewhere and you don´t know it. Have you checked the supply rails also? The problem could also be there...
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