Logitech 2.1 bass is too heavy - Will replacing the pot with a higher value fix it?
I submitted this post a few days ago but I guess I didn't provide enough information for anyone to respond. Also the pictures I provided had glue covering key components. -Sorry!
So let me try this again.
First of all, I'm not very experienced with electronics other than soldering obvious things like broken traces, loose resistors, capacitors etc... To give you an idea, I have to google Ohm's law everytime I need it.
Also, I know these are ridiculously cheap speakers with most-likely designed with a planned obsolescence, but I do love them
This time I made a detailed wiring diagram (click to enlarge):
Despite keeping the subwoofer level volume all the way down, they've always tended to still be a little boomy in the bass, which I would fix by rolling off the lower frequencies in winamp's EQ.
I would really like to fix the bass problem at the source so that I don't have to compensate via software, especially for connecting them directly to a tuner/mp3 player.
The subwoofer level control is a 10 kOhm linear taper pot that has all three legs leading to somewhat complicated (to me) circuits:
Both Leg 1 and Leg 2 (wiper) of the pot connect to the upper two opamps of the TL074CN from opposing directions via an array of resistors, capacitors and a couple of diodes. It really does look like they are opposite sides of the same circuit. I'm guessing that this circuit is the preamp for the subwoofer alone since you can see where both the left and right channels lead into the lower half of the TL074CN for the satellite speakers.
Leg 3 leads to the one of the outputs of a JRC4560D opamp.
The negative input for that amplifier gets fed from both the left and right input channels. The positive input for that amplifier comes from the two upper (subwoofer) opamps of the TL074CN via a complicated route that is connected to the base of the lone 2N3904 transistor.
Is the JRC4560D some sort of active EQ circuit?
If so, is it already defeated when the knob is set at "0" (as it always is)?
As you turn the subwoofer level knob up, does the pot simply apply the output of JRC4560D to both of the other Legs (1 and 2) in order to boost the bass?
If this is the way it works then it seems like my original idea of simply increasing the resistance of the pot won't work because the pot is already all the way down at zero.
Is there another solution that would (slightly) decrease the bass? Perhaps there is a resistor on the board that I could replace?
Thanks in advance for any expertise you can offer.
I submitted this post a few days ago but I guess I didn't provide enough information for anyone to respond. Also the pictures I provided had glue covering key components. -Sorry!
So let me try this again.
First of all, I'm not very experienced with electronics other than soldering obvious things like broken traces, loose resistors, capacitors etc... To give you an idea, I have to google Ohm's law everytime I need it.
Also, I know these are ridiculously cheap speakers with most-likely designed with a planned obsolescence, but I do love them
This time I made a detailed wiring diagram (click to enlarge):
Despite keeping the subwoofer level volume all the way down, they've always tended to still be a little boomy in the bass, which I would fix by rolling off the lower frequencies in winamp's EQ.
I would really like to fix the bass problem at the source so that I don't have to compensate via software, especially for connecting them directly to a tuner/mp3 player.
The subwoofer level control is a 10 kOhm linear taper pot that has all three legs leading to somewhat complicated (to me) circuits:
Both Leg 1 and Leg 2 (wiper) of the pot connect to the upper two opamps of the TL074CN from opposing directions via an array of resistors, capacitors and a couple of diodes. It really does look like they are opposite sides of the same circuit. I'm guessing that this circuit is the preamp for the subwoofer alone since you can see where both the left and right channels lead into the lower half of the TL074CN for the satellite speakers.
Leg 3 leads to the one of the outputs of a JRC4560D opamp.
The negative input for that amplifier gets fed from both the left and right input channels. The positive input for that amplifier comes from the two upper (subwoofer) opamps of the TL074CN via a complicated route that is connected to the base of the lone 2N3904 transistor.
Is the JRC4560D some sort of active EQ circuit?
If so, is it already defeated when the knob is set at "0" (as it always is)?
As you turn the subwoofer level knob up, does the pot simply apply the output of JRC4560D to both of the other Legs (1 and 2) in order to boost the bass?
If this is the way it works then it seems like my original idea of simply increasing the resistance of the pot won't work because the pot is already all the way down at zero.
Is there another solution that would (slightly) decrease the bass? Perhaps there is a resistor on the board that I could replace?
Thanks in advance for any expertise you can offer.
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