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

Digital Line Level DACs, Digital Crossovers, Equalizers, etc.

CSR8645 high pitch noise
CSR8645 high pitch noise
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
Thread Tools Search this Thread
Old 20th November 2019, 01:27 PM   #1
Avantu is offline Avantu
diyAudio Member
Join Date: Oct 2019
Default CSR8645 high pitch noise


I'm building myself stereo amplifier based on TDA7292 and CSR8645. My problem is that when i connect bluetooth module to amplifier there is very loud high pitch noise, similar to modem or data transfer. I power everything by IRM-60-24 and use LM317Ts to step down voltage for bluetooth and other periferials such as opamp LME47920. Once i tried lab power supply with 3 independent outputs, 24V for amplifier, 5V for transistor to activate amplifier and 3.3V for bluetooth and it was playing fine. But when i try to connect everything with IRM it is horrible. What can i do? Would it be better if i just connect 18650 battery to bluetooth? But i wanted it to run entirely on IRM-60-24 and idk what to do. Even when i used IRM only for amplifier and arduino or nucleo for 3.3 and 5V lines there was the same problem. Do you have any ideas? The sound doesn't have to be perfect at all, i just want to remove noise as cheaply and easy as possible, this whole thing is more like experiment than proper audio system.
  Reply With Quote
Old 20th November 2019, 06:00 PM   #2
Mark Tillotson is offline Mark Tillotson
diyAudio Member
Join Date: May 2018
Location: Cambridge UK
Sounds like a beat note between the SMPS's switching frequency and the Bluetooth unit's DAC sample rate. When such a beat note ends up in the audio range it will be very obvious - the solution is to change one of the frequencies (try a different PSU?). Alternatively aggressive filtering may be needed to knock down one or both ultrasonic notes.
  Reply With Quote
Old 21st November 2019, 09:14 AM   #3
Avantu is offline Avantu
diyAudio Member
Join Date: Oct 2019
I have tried laptop power supply and lab power supply with no better results. (arduino and nucleo also as I mentioned before.) Maybe problem is somewhere else?
  Reply With Quote
Old 23rd November 2019, 01:48 PM   #4
Markw4 is offline Markw4  United States
diyAudio Member
Join Date: Jul 2016
Location: California
Switching power supplies can make some RF noise, both conducted and radiated. Hard to say much based on the information you have provided so far.

When you say you hook up a blue tooth module does that mean it is the only available input device and its output is routed to the amplifier at all times, or can you switch to another input device while blue tooth is still powered up? The idea would be to try to figure out if the noise is coupled through the power supply, if the blue tooth module needs more power filtering when powered from an smps, or what. Many different possible things might be wrong, and we know nothing about the details of what you have done.

If you want to post clear, close-up, high-resolution pictures of your design, and a schematic too, then maybe people here will have a better idea of what the problem might be.

Last edited by Markw4; 23rd November 2019 at 01:51 PM.
  Reply With Quote
Old 17th January 2020, 01:07 PM   #5
Kytan666 is offline Kytan666  United Kingdom
diyAudio Member
Join Date: Sep 2011
Location: London
I know this is a bit old but I had similar issues in the past and the best advice is to use a separate supply for the module. Running all on the same supply will generate the noise. You could try to filter some with a CRC setup at highr voltage and then drop to 5V but requires a lot of trial and error. Every time I had this setup I just added a small 5v/1a board from a phone charger and had no issues.
  Reply With Quote


CSR8645 high pitch noiseHide 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
Fluctuating high-pitch noise in op-amp circuit Rolox Analog Line Level 98 16th December 2019 11:30 AM
high pitch noise coming from my diy tube amp toty10 Instruments and Amps 9 23rd September 2019 09:59 AM
Dacmagic plus outputs only high pitch noise TheMadcap Digital Line Level 5 30th July 2019 09:57 PM
High Pitch tone / noise on F5TV2 CLiu Pass Labs 12 10th July 2013 03:19 AM
High Pitch Noise in tweeters bigrubes24 Car Audio 2 28th April 2005 01:39 AM

New To Site? Need Help?

All times are GMT. The time now is 03:31 AM.

Search Engine Optimisation provided by DragonByte SEO (Pro) - vBulletin Mods & Addons Copyright © 2020 DragonByte Technologies Ltd.
Resources saved on this page: MySQL 15.00%
vBulletin Optimisation provided by vB Optimise (Pro) - vBulletin Mods & Addons Copyright © 2020 DragonByte Technologies Ltd.
Copyright ©1999-2020 diyAudio