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

Bluetooth noise problem.
Bluetooth noise problem.
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 14th September 2019, 03:26 AM   #11
horst303 is offline horst303  Australia
diyAudio Member
 
Join Date: Nov 2009
Location: Sydney
You don't have to have two batteries, but it is the way to prove that there's some funky loops being introduced when you share a battery.
You can try a dc isolater a or a dc-dc converter, sometimes that works sometimes it doesn't, I have to say I have given up and now only use fully engineered bluetooth amps, because they are really cheap and work really well.
  Reply With Quote
Old 14th September 2019, 04:06 AM   #12
jackstraw is offline jackstraw  United States
diyAudio Member
 
Join Date: Jun 2016
What engineered bluetooth amp do you use? I've never been able to get away with using an amp with a built in bluetooth chip because of my single speaker setup. All the ones i've found are stereo, and i've been told you can't or shouldn't sum the left and right channel post amplification.

I've never heard of a dc isolator, and don't understand what a dc-dc converter would be (what's it converting to?), but i'll go do some research. Thanks again for taking the time to respond!
  Reply With Quote
Old 14th September 2019, 04:11 AM   #13
Indiglo is offline Indiglo  Australia
diyAudio Member
 
Join Date: Sep 2018
The CSR bluetooth chips are configurable, there are numerous parameters that can be changed. The CSRA64215 config is stored on the local spi flash chip.

It's possible that the CSR64215 onboard battery charger is enabled by default and that is inducing switching noise into the audio path. Is the battery charger enabled or disabled ? who knows, you will need to read the config to determine the state.

Buying a fully engineered product will already have the bluetooth chipset to have a optimised configuration and not one that is probably set with some default options.
  Reply With Quote
Old 14th September 2019, 04:52 AM   #14
ubergeeknz is online now ubergeeknz  New Zealand
diyAudio Member
 
Join Date: Aug 2018
See if this helps. https://www.diyaudio.com/forums/show....php?p=5895795
  Reply With Quote
Old 14th September 2019, 06:44 AM   #15
voltwide is offline voltwide  Ireland
diyAudio Member
 
Join Date: Jan 2010
The problem of these BT devices is pulsating current consumption combined with common gnd return lines. What can you do?
1. In case there is a symmetrical output, use this and feed into an symmetrical input.

2. Otherwise isolate pos supply input with a regulator or some resistance and put a low ESR blocking elco of several 100uF parallel to + and - terminal of the BT device.
__________________
tuby or not tuby, that is here the question!

Last edited by voltwide; 14th September 2019 at 06:50 AM.
  Reply With Quote
Old 14th September 2019, 02:52 PM   #16
jackstraw is offline jackstraw  United States
diyAudio Member
 
Join Date: Jun 2016
Thanks everyone! After reading your replies I did a search on dc-dc isolating converters. I found a video on youtube of a guy demonstrating the exact noise that i'm getting with this weird ground loop, and then adding a dc-dc converter to fix it. I'm going to give that a try, but I have a couple questions:

1) I'm running everything off 6x 18650 lithium batteries, in 3S2P. The voltage varies from between around 12.6v at full charge, down to something like 8.7v when the BMS shuts things down to prevent undercharging. I also use the amp while charging, and my AC-DC wall wart is 13v.

So, with that in mind, do I still use a 12v DC-DC isolating converter? Or, do i need to find one that can handle a range of input voltage from 8v-13v?

2) When shopping for these i'm finding that they are rated not just for voltage, but also output power and current. Do you guys have any idea how much power & current a bluetooth board like mine requires?

Thanks again everyone, i really appreciate the help!
  Reply With Quote
Old 14th September 2019, 05:56 PM   #17
ubergeeknz is online now ubergeeknz  New Zealand
diyAudio Member
 
Join Date: Aug 2018
Quote:
Originally Posted by jackstraw View Post



So, with that in mind, do I still use a 12v DC-DC isolating converter? Or, do i need to find one that can handle a range of input voltage from 8v-13v?



2) When shopping for these i'm finding that they are rated not just for voltage, but also output power and current. Do you guys have any idea how much power & current a bluetooth board like mine requires?



Thanks again everyone, i really appreciate the help!
1) I don't think the small modules come for a range of voltages, but they might. If the module will take 5v, step it down to 5v then use an isolation module for 5v

2) easiest way to know for sure is measure it. Most would be less than 5W though.
  Reply With Quote
Old 16th September 2019, 01:53 AM   #18
jackstraw is offline jackstraw  United States
diyAudio Member
 
Join Date: Jun 2016
Thanks Uber. I'm pretty sure the bluetooth module will take 5v but i'm checking. I'm trying to achieve the best possible battery life. In the past i've done similar things with a transistor, but i think a fair amount of energy gets wasted in the way of heat. Is there a more efficient way of doing it?
  Reply With Quote
Old 16th September 2019, 01:55 AM   #19
ubergeeknz is online now ubergeeknz  New Zealand
diyAudio Member
 
Join Date: Aug 2018
Quote:
Originally Posted by jackstraw View Post
Thanks Uber. I'm pretty sure the bluetooth module will take 5v but i'm checking. I'm trying to achieve the best possible battery life. In the past i've done similar things with a transistor, but i think a fair amount of energy gets wasted in the way of heat. Is there a more efficient way of doing it?
A switching "buck" converter is the way. Modules can be had for next to nothing. They also make eg. 12v-5v isolating power supplies.
  Reply With Quote
Old 16th September 2019, 02:04 AM   #20
jackstraw is offline jackstraw  United States
diyAudio Member
 
Join Date: Jun 2016
Thanks for the quick reply! Which would be more efficient, both energy wise, and cost wise? A 12v-5v switching "buck" converter + a 5v DC-DC isolating converter, or the 12v-5 isolating power supply you mentioned?
  Reply With Quote

Reply


Bluetooth noise problem.Hide 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
tpa3116 with bluetooth 5.0 hiss noise problem poisas Class D 4 22nd October 2018 12:56 PM
Bluetooth noise through input Hayden Analog Line Level 2 8th February 2017 01:42 PM
Amp suggestions for no noise and Bluetooth? nbriles2000 Class D 3 1st February 2017 10:18 PM
USB powering bluetooth = noise. Mortenhoe Power Supplies 3 20th September 2016 09:34 AM


New To Site? Need Help?

All times are GMT. The time now is 02:20 AM.


Search Engine Optimisation provided by DragonByte SEO (Pro) - vBulletin Mods & Addons Copyright © 2019 DragonByte Technologies Ltd.
Resources saved on this page: MySQL 14.29%
vBulletin Optimisation provided by vB Optimise (Pro) - vBulletin Mods & Addons Copyright © 2019 DragonByte Technologies Ltd.
Copyright ©1999-2019 diyAudio
Wiki