I have this PAM8406 board that I am contemplating using in an outside music/radio player.
Out of the box, connected to an RPi/Boss DAC, it works very well, connected to a 5v powerbank.
I'd like to experiment with the mode settings (as well as implementing the mute and standby facilities) to see if I can hear an SQ difference between the Class D mode and the Class A/B mode.
Out of the box, all pins are high (ie class d is default, with mute and shutdown disabled). To change the mode, is it a case of simply connecting the pin to GND, or do I need to use a pull down resistor?
For the mute and shutdown options, I'd like to implement a 3 position switch; again is it a case of connecting the pins to GND via the switch, or do I need to use resistors?
Any advice appreciated!
Out of the box, connected to an RPi/Boss DAC, it works very well, connected to a 5v powerbank.
I'd like to experiment with the mode settings (as well as implementing the mute and standby facilities) to see if I can hear an SQ difference between the Class D mode and the Class A/B mode.
Out of the box, all pins are high (ie class d is default, with mute and shutdown disabled). To change the mode, is it a case of simply connecting the pin to GND, or do I need to use a pull down resistor?
For the mute and shutdown options, I'd like to implement a 3 position switch; again is it a case of connecting the pins to GND via the switch, or do I need to use resistors?
Any advice appreciated!
Hi Yatsushiro,
I'd like to experiment with the mode settings (as well as implementing the mute and standby facilities) to see if I can hear an SQ difference between the Class D mode and the Class A/B mode.
I understand your curiosity. When I heard that you can choose between class D and class AB I had to read the datasheet. Class D and class AB are quite different circuits. But indeed, the datasheet states you can. Pin 9 "MODE".
I only know the PAM8403 and 8610 and there are no alternative modes.
Out of the box, all pins are high (ie class d is default, with mute and shutdown disabled). To change the mode, is it a case of simply connecting the pin to GND, or do I need to use a pull down resistor?
That depends on the layout of the board. The simplest for the production is just to take the supply rail to these pins as well. If so, you cannot just pull them to ground as you will pull down the whole supply rail.
What to do? Take your Ohm-meter and measure the impedance from each of the three inputs and to the positive supply rail. Below 10 KOhm you have to be careful. Also, check the impedance from each of the three inputs and to the other inputs. Theoretically, they could have connected the three inputs together and pulled them up with a single resistor.
Since the board is marked with the different options, each input is likely to be pulled up by an individual resistor.
For the mute and shutdown options, I'd like to implement a 3 position switch; again is it a case of connecting the pins to GND via the switch, or do I need to use resistors?
If the inputs have individual pull-up resistors (>10K) you can pull them down to GND with switches.
Any advice appreciated
No problem. My guess is that class D sounds best.
I'd like to experiment with the mode settings (as well as implementing the mute and standby facilities) to see if I can hear an SQ difference between the Class D mode and the Class A/B mode.
I understand your curiosity. When I heard that you can choose between class D and class AB I had to read the datasheet. Class D and class AB are quite different circuits. But indeed, the datasheet states you can. Pin 9 "MODE".
I only know the PAM8403 and 8610 and there are no alternative modes.
Out of the box, all pins are high (ie class d is default, with mute and shutdown disabled). To change the mode, is it a case of simply connecting the pin to GND, or do I need to use a pull down resistor?
That depends on the layout of the board. The simplest for the production is just to take the supply rail to these pins as well. If so, you cannot just pull them to ground as you will pull down the whole supply rail.
What to do? Take your Ohm-meter and measure the impedance from each of the three inputs and to the positive supply rail. Below 10 KOhm you have to be careful. Also, check the impedance from each of the three inputs and to the other inputs. Theoretically, they could have connected the three inputs together and pulled them up with a single resistor.
Since the board is marked with the different options, each input is likely to be pulled up by an individual resistor.
For the mute and shutdown options, I'd like to implement a 3 position switch; again is it a case of connecting the pins to GND via the switch, or do I need to use resistors?
If the inputs have individual pull-up resistors (>10K) you can pull them down to GND with switches.
Any advice appreciated
No problem. My guess is that class D sounds best.
Last edited:
Thanks FF, looks like a session with a multimeter, pencil and notepad is in order.
Looking at the top right hand corner of the board in the top picture, there appears to be a small SMD resistor below the 'Mode' contact pad, in line with the 'H' (for High?). On the other side of the row of contact pads is an empty SMD mount point, in line with the 'L' (for low). Per your suggestion that "Theoretically, they could have connected the three inputs together and pulled them up with a single resistor" Do you think it would be a case of swapping the resistor from one side to the other, or is that too easy?
Looking at the top right hand corner of the board in the top picture, there appears to be a small SMD resistor below the 'Mode' contact pad, in line with the 'H' (for High?). On the other side of the row of contact pads is an empty SMD mount point, in line with the 'L' (for low). Per your suggestion that "Theoretically, they could have connected the three inputs together and pulled them up with a single resistor" Do you think it would be a case of swapping the resistor from one side to the other, or is that too easy?
I found some photos on "Banggood.com" indicating that the three inputs are "hard-tied" with small resistors marked with a "0" (acting as jumpers). As it looks with an "L"-side and a "H"-side, if you remove a "0"-jumper on the "H"-side and move it to the "L"-side (tricky job with these small jumpers) that input is connected low instead. That may work for class D/AB (MODE) but not for the two other inputs as the amplifier remains inactive.
Please check with the Ohm-meter first to be sure.
Better is to replace the "0"-jumpers ("H"-side) with 10K resistors and the "L"-side pads with micro-switches. It is not going to be easy with the tiny dimensions.
They say you have 2 days with sun and Monday the clouds return. Happy Easter.
Please check with the Ohm-meter first to be sure.
Better is to replace the "0"-jumpers ("H"-side) with 10K resistors and the "L"-side pads with micro-switches. It is not going to be easy with the tiny dimensions.
They say you have 2 days with sun and Monday the clouds return. Happy Easter.
- Status
- This old topic is closed. If you want to reopen this topic, contact a moderator using the "Report Post" button.