Go Back   Home > Forums > >
Home Forums Rules Articles diyAudio Store Blogs Gallery Wiki Register Donations FAQ Calendar Search Today's Posts Mark Forums Read

Class D Switching Power Amplifiers and Power D/A conversion

PAM8406 Mode Setting Help
PAM8406 Mode Setting Help
Please consider donating to help us continue to serve you.

Ads on/off / Custom Title / More PMs / More album space / Advanced printing & mass image saving
Reply
 
Thread Tools Search this Thread
Old 19th April 2019, 12:42 PM   #1
Yatsushiro is offline Yatsushiro  France
diyAudio Member
 
Join Date: Mar 2016
Location: Normandie, France
Default PAM8406 Mode Setting Help

I have this PAM8406 board that I am contemplating using in an outside music/radio player.

Click the image to open in full size.

Click the image to open in full size.

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!
  Reply With Quote
Old 19th April 2019, 07:26 PM   #2
FauxFrench is offline FauxFrench  France
diyAudio Member
 
Join Date: Dec 2017
Location: The mountains, calm and quiet.
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.

Last edited by FauxFrench; 19th April 2019 at 07:33 PM.
  Reply With Quote
Old 20th April 2019, 09:41 AM   #3
Yatsushiro is offline Yatsushiro  France
diyAudio Member
 
Join Date: Mar 2016
Location: Normandie, France
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?
  Reply With Quote
Old 20th April 2019, 11:16 AM   #4
FauxFrench is offline FauxFrench  France
diyAudio Member
 
Join Date: Dec 2017
Location: The mountains, calm and quiet.
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.
  Reply With Quote

Reply


PAM8406 Mode Setting HelpHide this!Advertise here!
Thread Tools Search this Thread
Search this Thread:

Advanced Search

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off

Forum Jump

Similar Threads
Thread Thread Starter Forum Replies Last Post
PAM8406 (and PAM8403) Jensen567 Class D 30 6th April 2019 12:24 PM
Difference between voltage mode and current mode Class D amps? Chris Wilson Class D 3 30th January 2019 07:58 PM
Setting levels when using 'Bridged mode' - Clarion theoracle Car Audio 6 2nd June 2017 01:51 AM
WM8741 in Dual differential mode and 2-wire control mode BMW850Ci Digital Line Level 14 14th October 2011 07:39 AM
Using a spdt switch to select between triode mode and pentode mode on a guitar amp. G Instruments and Amps 19 15th March 2006 09:15 AM


New To Site? Need Help?

All times are GMT. The time now is 02:09 PM.


Search Engine Optimisation provided by DragonByte SEO (Pro) - vBulletin Mods & Addons Copyright © 2019 DragonByte Technologies Ltd.
Resources saved on this page: MySQL 15.00%
vBulletin Optimisation provided by vB Optimise (Pro) - vBulletin Mods & Addons Copyright © 2019 DragonByte Technologies Ltd.
Copyright ©1999-2019 diyAudio
Wiki