Case Layout for Headphone Amp and RPi - diyAudio
Go Back   Home > Forums > Amplifiers > Headphone Systems
Home Forums Rules Articles diyAudio Store Gallery Wiki Blogs Register Donations FAQ Calendar Search Today's Posts Mark Forums Read

Headphone Systems Everything to do with Headphones

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 8th January 2016, 10:22 PM   #1
Bibio is offline Bibio  Scotland
diyAudio Member
 
Bibio's Avatar
 
Join Date: Mar 2009
Default Case Layout for Headphone Amp and RPi

before i go down the workshop and punch out the casework on my friends turret punch can anybody see any potential problems with the layout below?

bottom tray:
Click the image to open in full size.

Thanks
  Reply With Quote
Old 9th January 2016, 11:39 AM   #2
arpagon is offline arpagon  Bulgaria
diyAudio Member
 
Join Date: Oct 2011
I suppose the two small PCBs are rectifier bridges+capacitors, right?
Why don't you try to put any of them closer to corresponding amplifier PCB?
What is the white area in the upper right corner? Is it reserved for something?
What is the white rectangle between toroidals? Can you try to put there rectifier boards instead?

Regards
  Reply With Quote
Old 9th January 2016, 02:37 PM   #3
Bibio is offline Bibio  Scotland
diyAudio Member
 
Bibio's Avatar
 
Join Date: Mar 2009
upper right is Raspberry Pi.
two small PCB's are regulators, one for RPi and the other is for the USB extension (sort of powered hub).
white area between the trafo's is rectification for the headphone amps.

my only concern is the trafos causing interference. size of tray is w=280mm d=270mm
  Reply With Quote
Old 10th January 2016, 02:00 PM   #4
Jpaul is offline Jpaul  United States
diyAudio Member
 
Join Date: Feb 2015
Quote:
Originally Posted by Bibio View Post
upper right is Raspberry Pi.
two small PCB's are regulators, one for RPi and the other is for the USB extension (sort of powered hub).
white area between the trafo's is rectification for the headphone amps.

my only concern is the trafos causing interference. size of tray is w=280mm d=270mm
@Bibio, may I ask if you are using a Raspberry Pi i2s dac mounted on the Pi, and placed inside this same case?
  Reply With Quote
Old 10th January 2016, 02:04 PM   #5
diyAudio Member
 
Join Date: Nov 2004
Location: Germany
Your concerns may be warranted since I'm potentially seeing a big ground loop there, which needless to say, is an invitation for magnetic coupling. Your left and right audio grounds are inevitably going to be joined at both the RPi (with a DAC board, I guess?) and the headphone jack, while being split up on two amplifier boards in between. You will need to interrupt said ground loop somewhere on the amplifier boards, and if it involves just a 10 ohm resistor or so. Other than that, it looks OK - orient the transformer end with the wiring coming out away from the electronics in the final thing.

TBH, going dual mono in a headphone amplifier has zero benefits and a number of drawbacks. It only ever makes any sense for a balanced headphone amp, balanced headphones featuring nicely separated signal returns.
  Reply With Quote
Old 10th January 2016, 03:32 PM   #6
Bibio is offline Bibio  Scotland
diyAudio Member
 
Bibio's Avatar
 
Join Date: Mar 2009
Quote:
Originally Posted by Jpaul View Post
@Bibio, may I ask if you are using a Raspberry Pi i2s dac mounted on the Pi, and placed inside this same case?
yes, at the moment i'm using an iqaudio dac+ but i'm thinking of swapping it out for the hifiberry dac+ pro. i remove the phono sockets and wire direct to the headphone boards.

Quote:
Originally Posted by sgrossklass View Post
Your concerns may be warranted since I'm potentially seeing a big ground loop there, which needless to say, is an invitation for magnetic coupling. Your left and right audio grounds are inevitably going to be joined at both the RPi (with a DAC board, I guess?) and the headphone jack, while being split up on two amplifier boards in between. You will need to interrupt said ground loop somewhere on the amplifier boards, and if it involves just a 10 ohm resistor or so. Other than that, it looks OK - orient the transformer end with the wiring coming out away from the electronics in the final thing.

TBH, going dual mono in a headphone amplifier has zero benefits and a number of drawbacks. It only ever makes any sense for a balanced headphone amp, balanced headphones featuring nicely separated signal returns.
yup i already have a ground loop on my test bed but its a weird one, there is a bad hum until i start to play music at which stage the RPi DAC somehow removes it and will continue until i cold boot the RPI again. upon first turn on of the system there is a HUMMMM then when i start to play music its an inky black silence.

the dual trafos is what Richard recommends for his Sapphire headphone amp.
  Reply With Quote
Old 10th January 2016, 08:08 PM   #7
Jpaul is offline Jpaul  United States
diyAudio Member
 
Join Date: Feb 2015
Quote:
Originally Posted by Bibio View Post
yes, at the moment i'm using an iqaudio dac+ but i'm thinking of swapping it out for the hifiberry dac+ pro.
I see that the dac+ pro has two clocks. I also have some iQaudio dacs, as well as some Audiophonics dacs. The latest audiophonics use saber es9023 with tcxo clocks.
I'll be following your posts on your combination Sapphire/Pi/dac setup.
Very interesting to me.
  Reply With Quote
Old 11th January 2016, 12:04 AM   #8
Bibio is offline Bibio  Scotland
diyAudio Member
 
Bibio's Avatar
 
Join Date: Mar 2009
i'm a bit slow at doing things so it might take a while.. lol
  Reply With Quote
Old 15th January 2016, 04:05 PM   #9
diyAudio Member
 
Join Date: Nov 2004
Location: Germany
Quote:
Originally Posted by Bibio View Post
yup i already have a ground loop on my test bed but its a weird one, there is a bad hum until i start to play music at which stage the RPi DAC somehow removes it and will continue until i cold boot the RPI again. upon first turn on of the system there is a HUMMMM then when i start to play music its an inky black silence.
That probably means that once turned on, the output amplifier of the DAC will remain active, providing a low source impedance. Getting a hum when the output is essentially open circuit is nothing too unexpected and not necessarily an indication of a ground loop, but possibly of insufficient shielding.
  Reply With Quote
Old 15th January 2016, 08:03 PM   #10
Bibio is offline Bibio  Scotland
diyAudio Member
 
Bibio's Avatar
 
Join Date: Mar 2009
hhhmmm, thats interesting but also disturbing.

i have a dedicated mains line from my consumer unit that powers my audio/multimedia system in my living room. i had this and extra sockets installed when i moved in about 20 years ago and recently i had my consumer unit replaced.

well today i decided that i would try my pifi on another spur in the house (kitchen) and to my surprise when i turned the headphone amp on without the RPi being plugged in i was greeted with silence, not a bit of hum to be heard where before it would hum like a good one. i then turned the RPi on and i now get a buzz instead of a hum so i can put that down to the wall wart that powers my regulator that powers the RPi.

am i happy? hell yes but i'm also disturbed as i now have to track down why i'm getting a bad hum from the mains in my livingroom.
  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
Headphone amp on perfboard: layout critics welcome Preamp Headphone Systems 12 21st April 2014 07:26 PM
Volumio and Rpi DAC tjaekel PC Based 1 5th February 2014 03:34 PM
M3 Headphone Amp with wood/aluminum case with Sigma 11 PSU / Epsilon 12 (DIY AMB) mfspdesigns Vendor's Bazaar 2 16th December 2013 03:07 PM
Class D Audio aluminum case or DIY amp case jtwrace Vendor's Bazaar 3 17th April 2010 03:51 PM
headphone amp in 9V battery case needtubes Headphone Systems 4 15th December 2003 07:05 PM


New To Site? Need Help?

All times are GMT. The time now is 04:34 PM.


vBulletin Optimisation provided by vB Optimise (Pro) - vBulletin Mods & Addons Copyright © 2016 DragonByte Technologies Ltd.
Copyright 1999-2016 diyAudio

Content Relevant URLs by vBSEO 3.3.2
Wiki