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  1. Audioguru

    A Stretch

    The gain control sets how much distortion is produced by the diodes, because a diode conducts when the voltage across it tries to be more than about 0.7V and the gain control sets the opamp gain from 1 (unity gain) when the gain pot is a short circuit between the opamp output and its -In to a...
  2. Audioguru

    A Stretch

    Audio buzzing is caused by each long messy breadboard wire (including the wires on resistors and capacitors) is an antenna that picks up the 50Hz or 60Hz from the electricity wires all over your home or business. That is why the circuits I make on stripboard are compact and tidy. Also, the wires...
  3. Audioguru

    A Stretch

    I agree that the recording has no distortion. It sounds like the entire "overdrive circuit" is simply a piece of wire. The gain control should make the sound like a piece of wire with no distortion when shorted to extremely distorted when turned to 500k ohms. The wrong voltage on the opamp...
  4. Audioguru

    A Stretch

    The circuit does not have a 500k volume control. Maybe you wrongly use the 500k pot as a volume control and wrongly use the 100k pot as the gain control? Then the maximum gain will be 5 times less. You still have a problem with the too high voltage at the opamp output. Maybe the Mickey Mouse...
  5. Audioguru

    Adding aux functionality to old boat radio

    Nearly all modern car radios (and marine radios are probably the same) DO NOT have the black wires of their speakers connected together because the outputs are 'bridged". A bridged output has a separate amplifier for each speaker wire to produce more power.
  6. Audioguru

    A Stretch

    No. C30 connects to +4.5V, NOT to +9V. The power part of the circuit has only two resistors, two capacitors and a battery. how can it be wrong? Solderless breadboards are a nightmare of intermittent connections and wires all over the place. Instead, I make a neat and tidy drawing showing all...
  7. Audioguru

    The Adventure Continues......

    The second opamp is a tone control that is better than the first circuit has. Do you need a tone control?
  8. Audioguru

    The Adventure Continues......

    I turned your new circuit upside down to show you that it is the same circuit as your first circuit.
  9. Audioguru

    A Stretch

    The voltage at pin 6 of the opamp is wrong, it is much too high. It should be +4.5V. The 4.5V (measure it) is formed by the voltage divider of R32 and R33 then it is passed to the pin 3 input of the opamp. Check that R32 and R34 are the same values. Your gain control is correctly connected but...
  10. Audioguru

    A Stretch

    The diodes cause the distortion. If the gain control is turned down too low then it shorts the diodes causing no distortion. Turn up the gain control for the diodes to cause distortion.
  11. Audioguru

    A Stretch

    What do you have connected to the output of this overdrive preamp? it cannot drive a speaker, it is supposed to be connected to an audio power amplifier's input and its ground. If you are using a 220nF film capacitor for C28 then it will be marked 224. If you have a voltmeter then when the...
  12. Audioguru

    A Stretch

    Most overdrive circuits are the same, but if your new circuit is different then please begin a new thread for it.
  13. Audioguru

    A Stretch

    The circuit is a common one with a good design. With the diodes it causes overdrive distortion. With the polarity of C3 backwards it causes more distortion. Amazon is not a reliable electronic parts distributor so maybe their parts are fake or defective. EDIT: I disagree with its tone control...
  14. Audioguru

    A Stretch

    When you turn up the "gain" pot then there will be LOTS of overdrive distortion caused by the diodes.
  15. Audioguru

    A Stretch

    Non-polarized film capacitors are used for coupling signals in low distortion audio circuits. But since you want distortion in this circuit then a polarized electrolytic capacitor connected backwards will make additional awesome distortion.
  16. Audioguru

    A Stretch

    You bought a pot that is labelled POT LIN. Lin means linear. It can be used but it will be difficult to adjust since a volume control is usually a LOGarithmic one.
  17. Audioguru

    A Stretch

    Ceramic capacitors have a wide range of tolerance, produce audio distortion and act like a microphone to knocks. Film capacitors do not have these problems. The TL082 dual opamp should not be used, a TL081 single opamp is all you need and if you use a socket for it then you can easily replace...
  18. Audioguru

    A Stretch

    Instead of me looking for these simple things, you should look for them in Google Images.
  19. Audioguru

    A Stretch

    Ceramic capacitors are not used for audio, they are used in high frequency radio circuits and power supplies. 220nF is usually a non-polarized film capacitor. Here is what they look like:
  20. Audioguru

    A Stretch

    Usually a 470nF capacitor (0.47uF) is a non-polarized film type (marked 474). All 470uF capacitors are 1000 times the value and are polarized electrolytic type. Use a film type of capacitor.
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