[Advice Needed] DAC Balanced output filters + Gain stage

Hofmann · 1st December 2020, 04:56 PM

I want to add balanced xlr outputs to my DIY CS4398 DAC.
I am honestly a little clueless in my design choices, so any advice would be appreciated.

Mainly: Is this the right way of doing balanced volume control using opamps?

Secondary: I plan on adding a relay to pull the signal to ground to mute (see the flags labeled 'mute' near the volume control pot). However with this method will leave the signal trace on the pcb open when not muting and I'm worried it will work as a nice little antenna for EMI.

The output filter stage is taken directly form the CS4398 datasheet.

I've also added a screenshot of my current progress with the pcb layout. Something got messed up with the component annotations, so these might not correspond with the ones in the schematics.

rayma · 06:05 PM

The muting could be a short between the phases, rather than connecting each phase to ground.
The volume circuit should work ok.

Hofmann · 2nd December 2020, 01:09 PM

You are right, I was plan on doing it this way but I guess I forgot that while typing the post.

However when the signal is not muted, the open traces to the relay might pick up interference. Is this a genuine concern or am I just overthinking it now?

1st December 2020, 06:01 PM	#2
rayma diyAudio Member Join Date: Apr 2011	The muting could be a short between the phases, rather than connecting each phase to ground. The volume circuit should work ok. Last edited by rayma; 1st December 2020 at 06:05 PM.

Similar Threads
Thread	Thread Starter	Forum	Replies	Last Post
FS: Balanced tube gain stage (line stage, dac output...)	DIYspaceW	Swap Meet	10	Yesterday 07:00 AM
true balanced, fake balanced and other balanced amps	studiophone	Solid State	4	6th May 2020 07:58 AM
adding balanced output capability to my unbalanced 4-ch gain stage circuit	CharlieLaub	Analog Line Level	17	14th April 2017 11:56 PM
Advice needed: Output stage in Sony TA-E9000ES (CXA8042AS DAC)	Groundloops	Digital Source	2	22nd June 2011 04:20 AM
EMI ac line filters & RFI ac line filters. Are they one and the same?	KevinLee	Parts	1	8th January 2003 01:18 AM

New To Site?	Need Help?
Register to Participate Privacy Statement Contact Us	Frequently Asked Questions Did you forget your password? Mark Forums Read


	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

2nd December 2020, 01:09 PM	#3
Hofmann diyAudio Member Join Date: Apr 2018	You are right, I was plan on doing it this way but I guess I forgot that while typing the post. However when the signal is not muted, the open traces to the relay might pick up interference. Is this a genuine concern or am I just overthinking it now?