Can someone measure DC offset from RCA analog output on the Ultra ?

Musician

Senior Member
Joined
Dec 10, 2023
Messages
403
Some of us ( like me ) use power amps without DC protection ( i.e. Hypex ncore ) . I want to know if there is any DC on the analog rca output for the Ultra.
Can someone measure this ? Onlyoneme ?
 
0.25 mV in idle, 1.2 mV for full scale 1 kHz sine.
And I got above 1 V DC for songs which are known for DC content. So no DC offset protection.
 
Simply avoid dangerous songs. I hope that they are not available in the music services.
 
Can you
Simply avoid dangerous songs. I hope that they are not available in the music services.
Can you give an example? This is new to me (been an "audiophile" for 35 years :ROFLMAO:) and frankly haven't heard of this issue before.
 
Simply avoid dangerous songs. I hope that they are not available in the music services.
"Hope is not a strategy" ;)
There are certain songs where my RME dac complains about DC, yet I've played them on my other systems with no apparent problems.
Maybe 'apparent' is the operative word here...
 
I'm curious to knowing the purposes to have a full DC coupled audio amplifier, maybe they don't trust on capacitors? Are marketing purposes or even a response cut at one or two hertz it's too much and hurts the ears?
 
0.25 mV in idle, 1.2 mV for full scale 1 kHz sine.
And I got above 1 V DC for songs which are known for DC content. So no DC offset protection.
Thanks Obi-wan !

0.25 mV in idle is not alarming, probably because the opa1611 has low DC offset and are probably set to unity gain at the output ( used as buffer ) .

Ok….. there is some dc offset on the output on some material so one could have a 2 uF polypropylene capacitor in series with each of the rca + channel input in a Hypex ncore amplifier to be 100% safe. The ncore 125 and I suppose 250 has an input impedance of 50 Kohm. Those capacitors as example can be soldered on the inside of the power amps rca + sockets.

The frequency response will be down -6 dB at 1,6 Hz . No guarantee are valid after this operation, but it can be done .

IMG_0957.jpeg
 
Last edited:
I'm curious to knowing the purposes to have a full DC coupled audio amplifier, maybe they don't trust on capacitors? Are marketing purposes or even a response cut at one or two hertz it's too much and hurts the ears?
So, why dont they use dc coupling capacitors on the analog output of the WiiM Ultra? Maybe for a couple of reasons.

Maybe they dont need to when using Opa 1611, especially in unity gain ?
It might also sound better without capacitor If the power amp already has dc protection . Most pre and poweramps have that. The Hypex ncore dont.

You will need some DC protection at the output of the source, or at the input of the power amp.

As this can be seen as a less good thing with the Ultra, we must remember that the low 11 Ohm output impedance is a really good thing were most japanese streamers have 500 ohm - 1 Kohm and cant drive some poweramps with lower input impedance.
 
Last edited:
I was referring to input of power amplifier. I can't se any operating reason to not already insert a capacitor like you posted.
Static DC offset on output of any good op amp are generally low and not a problem. DC offsets from bad digital mastering, can be more harmful and any power amp inputs should consider this.
Maybe it's just a philosophical thinking but I see more logic and safe, to put the decoupling on power amp inputs.
Anyway, the suggested capacitor, can be mounted on a cable itself, without voiding warranty.
 
I was referring to input of power amplifier. I can't se any operating reason to not already insert a capacitor like you posted.
Static DC offset on output of any good op amp are generally low and not a problem. DC offsets from bad digital mastering, can be more harmful and any power amp inputs should consider this.
Maybe it's just a philosophical thinking but I see more logic and safe, to put the decoupling on power amp inputs.
Anyway, the suggested capacitor, can be mounted on a cable itself, without voiding warranty.
Yes, thats good advice: - inside a rca contact with a physically smaller cap, or split the rca cables in the middle with a little box containing one capacitor in series with + per channel.
 
You will need some DC protection at the output of the source, or at the input of the power amp.
It's not too uncommon to design electronics in such a way that each device has to protect itself from DC, if required. DC protected input, directly coupled output.
 
I use a Ncore amp without any issues. Haven't meassured though.
I have measured the DC offset on my Hypex ncore at the amplifiers loudspeaker output terminal with Ultra connected , it was only 2 mV so theres no worry

 
Last edited:
Back
Top