PCB routing for audioamps - Page 4 - diyAudio
Go Back   Home > Forums > Amplifiers > Solid State

Solid State Talk all about solid state amplification.

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 22nd January 2007, 03:25 AM   #31
diyAudio Moderator Emeritus
 
lumanauw's Avatar
 
Join Date: Oct 2002
Location: Bandung
Send a message via Yahoo to lumanauw
If an amp has audible parasitic noise (like intermittent rat sound), where does this comes from? I'm making self-oscilating classD experiment, it drives me bananas

Phase Accurate has warned that in classD, the PCB itself is the most important component.

Do you have guidelines for classD selfoscilating PCB? What are the guidelines for drawing self-oscilating classD PCB?
  Reply With Quote
Old 22nd January 2007, 03:40 PM   #32
diyAudio Member
 
Join Date: Nov 2005
Default Connecting the input-signal to pcb siuting connectors?

Hello,

I like the possibility to mount the pcb itsself to the heatsink and then mount the heatsink into the chassis, and then doing the wirering.

For the power-connections its no problem to find connectors, but no chance for the input signal.

One day I started to implement normal cinch/RCA jacks like these:

http://www.computerkabelversand.de/p...nbaubuchse.jpg

on my PCBs. I know there are special jacks for printed boards, but I dont need 90 degree mount jacks.

Looks like this:

http://i2.photobucket.com/albums/y23...6/Lm3886_6.jpg

-------------

On my own pcbs its no problem to do it this way (still not being ideal), but other layouts mostly are desinged to solder the inputs direktly to the board, but IMO thats not very practical.

On Quasis Pcbs I am going to use these:

http://www.reichelt.de/bilder//web/b...C180/RTM13.jpg

->RLP-Version


What is your way to connect the input?


Input appreciated!
Black
  Reply With Quote
Old 23rd January 2007, 02:59 AM   #33
bscally is offline bscally  United States
diyAudio Member
 
Join Date: May 2005
Location: USA at the moment
Quote:
Originally posted by sam9


Are you shure it's not really for distilling moonshine?

Halco Output colis. Yummy. Definetly distilling something.

Brian
  Reply With Quote
Old 23rd January 2007, 04:17 AM   #34
diyAudio Member
 
jackinnj's Avatar
 
Join Date: Apr 2002
Location: Llanddewi Brefi, NJ
Quote:
Originally posted by SM2GXN
Thanks for all replies!

Excellent pcb Jens!
Very symetrical, guess that a double sided board play a big role and that you spent some hours to make the final finish, real nice artwork. Bad thing with double sided board for most hobbyist is that it is a bit tricky to make them. Does your amp get less noisy by using a groundplane like the one on your board?
Good points you've made 1-5 they are already added to my library


Symetricality is one of many keys -- and an important one at that and I certainly concur.

It is also very helpful to keep the radiated energy from the power transformer away from the input circuitry. Bypass capacitors as near as possible to the pins as possible and without long legs to ground (elsewise they become a radiator.)

I spoke with one IC power-opamp firm and they said that there was a difference in measured THD% stats when they twisted the power supply cables --

My recommendation -- keep a notebook and date it. Every time you make a change in the circuitry or layout note the changes. (ok. I will admit to being a franco-phile as I use the Fontaine notebooks).
  Reply With Quote
Old 26th February 2007, 05:32 AM   #35
BWRX is offline BWRX  United States
diyAudio Moderator Emeritus
 
Join Date: Jan 2005
Location: Pennsylvania
Quote:
Originally posted by lumanauw
Phase Accurate has warned that in classD, the PCB itself is the most important component.

Do you have guidelines for classD selfoscilating PCB? What are the guidelines for drawing self-oscilating classD PCB?
The PCB layout is just as important as the components for class d, especially with higher switching frequencies, voltages, and currents.

One of the keys of class d layout is keeping loop area small wherever larger currents (with high rise times) are flowing (i.e. the traces between the supply caps and the mosfets and between the mosfets and the inductor).

Grounding is also very important (particularly with unbalanced configurations). You definitely don't want those high currents flowing through or near signal grounds. That can introduce problems that can be very difficult to find and diagnose.
__________________
Brian
  Reply With Quote
Old 3rd May 2012, 09:15 PM   #36
diyAudio Member
 
Join Date: Oct 2011
To move tracks for long distances a ground plane is useful. (Long distance) is relative to frequency.
Attached Images
File Type: png star.png (8.6 KB, 105 views)
File Type: png transmission line.png (12.9 KB, 100 views)

Last edited by OnAudio; 3rd May 2012 at 09:29 PM.
  Reply With Quote
Old 3rd May 2012, 09:16 PM   #37
diyAudio Member
 
Join Date: Oct 2011
When it comes to PCB layout, think in-terms of stars and transmission lines. Combining stars and transmission lines is also a way to go. small capacitors between Ground plane and positive and or negative supply eliminate frequency notches for boards with power layers. If used the Ground layer should occupy the largest surface area. The layer carrying the positive or negative supply or both should limit their area to where they need to supply power.

For those tracks that may have a negative interaction with the ground plane via capacitive coupling, route them on ground plane with sufficient clearance.
Attached Images
File Type: png combined.png (5.2 KB, 95 views)

Last edited by OnAudio; 3rd May 2012 at 09:44 PM.
  Reply With Quote
Old 3rd May 2012, 11:06 PM   #38
jcx is offline jcx  United States
diyAudio Member
 
Join Date: Feb 2003
Location: ..
true transmission line design is not relevant to audio power amps - the very highest frequency you find in MOSFET amps is <10 MHz loop gain crossover frequency, 1 ft of wiring would ~= 500 MHz wavelength so even the 1/10 wave criteria for starting to worry about transmission line phenomena isn't met

as mentioned earlier routing large, fast changing current paths and their returns toether reduces inductance, mag field coupling to other parts of the amp - but this doesn't happen spontaneously at audio frequencies - the frequencies are too low to form "image" return current paths as in high speed digital ground plane use

audio currents are mostly resistance controlled - you have to explicitly route the returns to minimize radiated field, ground planes are useful in the low level circuits if you have arranged the gnd Hierarchy to keep large, distorted, "dirty" current return paths from flowing through it
  Reply With Quote
Old 4th May 2012, 05:28 AM   #39
Bonsai is offline Bonsai  Taiwan
diyAudio Member
 
Bonsai's Avatar
 
Join Date: Jul 2003
Location: Taipei, Taiwan
jcx, yes, I agree with these points.

One point to note is that twisting the supply lines and ground together in a class AB amplifers brings little advantage, and in some cases may make matters worse. The supply rails will be conducting big, half wave rectified currents at the signal frequencies and related harmonics. On the amplifer side that is not conducting, with twisted supply lines you can get coupling into the small signal stages that can cause problems. A good trick is to feed you amplifer with a 1KHz signal and look at the output on a spectrum analyzer (sound card is ok). Then move your supply, speaker and ground return lines around, looking for the least contamination.

Syn08 talk about some of the struggles he had wrt power supply hookup and layout in the <1ppm PGP. Check the PGP website out - some good engineering there.
__________________
bonsai
Amplifier Design and Construction for MUSIC! http://hifisonix.com/
  Reply With Quote

Reply


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
Trackbacks are Off
Pingbacks are Off
Refbacks are Off


Similar Threads
Thread Thread Starter Forum Replies Last Post
PCB Routing Mark245 Parts 15 27th May 2009 08:54 PM
Routing aluminium? EC8010 Everything Else 43 27th November 2007 01:31 AM
eagle routing djronbxs Everything Else 1 21st September 2007 07:45 PM
Routing advice Glen1 Subwoofers 14 24th May 2007 05:02 PM
MDF cnc routing dhole Multi-Way 1 21st January 2006 05:38 PM


New To Site? Need Help?

All times are GMT. The time now is 09:55 PM.


vBulletin Optimisation provided by vB Optimise (Pro) - vBulletin Mods & Addons Copyright © 2014 DragonByte Technologies Ltd.
Copyright 1999-2014 diyAudio

Content Relevant URLs by vBSEO 3.3.2