Portable Amp/DAC 4.4mm Output Distortion

[BobSmith]

Hello community, maybe someone might have some insight.

I'm going to post this generically without naming the portable Amp/DAC:

If you had an Amp/DAC that had the following issue what could it possibly be?

This is one of those dongle type Amp/DACs that connect to a smartphone via USB-C for out boarding Amp/DAC duties.

Problem:

When using the phone for music listening using any number of local players or Tidal (Android app or UAPP) streaming, using any given headphone out of the 4.4mm connector, sound is distorted, like when an amp is overdriven. Happens with any phone or DAP, any cable and any set of cans. 4.4mm output also seems to exhibit some EMI pickup from source.

Using the 3.5mm output alone, all is well, no distortion or EMI.

Big caveat: When listening on 4.4mm and sticking a 3.5mm headphone or 3.5mm to 3.5mm cable (in dummy cable mode, not connected to anything) into the 3.5mm jack and pressing the 3.5mm jack upwards, the 4.4mm sound clears up considerably but still with some remnant distortion/EMI.

Does this sound like some sort of grounding issue or something else?

Thanks for any ideas!

 

[voodooless]

I'm going to post this generically without naming the portable Amp/DAC

Why? Just name the damn product…

if using the 4.4mm output, do you use a balanced cable and balanced cans?

 

[BobSmith]

Why? Just name the damn product…

if using the 4.4mm output, do you use a balanced cable and balanced cans?

yep, balanced cable, balanced cans.

 

[Joachim Herbert]

It will distort unless it is named.

 

[BobSmith]

It will distort unless it is named.

Yeah, I know seems SAF but I've got a bit of a sensitive return issue hanging in the balance and don't want to name names. Just asking anyone on general principles why the distortion might stop by pushing up on the 3.5mm. Seemed like some kind of grounding issue to me.

 

[MaxwellsEq]

When listening on 4.4mm and sticking a 3.5mm headphone or 3.5mm to 3.5mm cable (in dummy cable mode, not connected to anything) into the 3.5mm jack and pressing the 3.5mm jack upwards, the 4.4mm sound clears up considerably but still with some remnant distortion/EMI.

Sounds like a fault, such as a poor solder joint or cracked track. I wouldn't assume it's specifically a grounding issue.

 

[BobSmith]

Sounds like a fault, such as a poor solder joint or cracked track. I wouldn't assume it's specifically a grounding issue.

That makes sense. Thanks!

 

[DVDdoug]

Yeah, something physical like a bad connection (a solder connection, etc.)


...Balanced headphones (4.4mm) are mostly a gimmick except you can potentially get double the voltage (6dB louder) and that MIGHT be important with the limited voltage from a USB powered device. If you don't have limited power supply voltage there are easier ways to get double (or more) output.